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Location:
Rosanna, Melb
Registered:
June 2002
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4A: G vs F heads
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Thu, 21 October 2004 13:47
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I just read a post by Bill Sherwood recently:
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I'd keep the 7AFE head, they're much better than the G head ever could be.
There's two type though, the twin-port per cylinder one which is okay, and the really good single port one.
I know a guy in Holland that gets 249hp from a 1.6 @ 9000 with the twin-port head in his off-road buggy.
No way a G head could do that.
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I know the G = sports and F = economy and all the basic stuff. But I was wondering if the above is true, and if so why? I've had a look around but can't find any info on this.
What is holding the factory 4 or 7AFE back behind the 4AGE? And what needs to be done to it to make this big power?
Any suggestions?
Thanks
Hen
PS, this is purely a hypothetical discussion, I currently have no plans to do this.
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Location:
Brisbane
Registered:
May 2002
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Re: 4A: G vs F heads
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Fri, 22 October 2004 00:06
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Anything Bill Sherwood says about A series engines is pretty much true. 
The distinction between F-type and G-type heads isn't as clear as it used to be. I think it has more to do with valve angle (narrow vs wide) rather than performance vs economy... I mean look at the 1UZ-FE, you'd hardly call that an economy engine!
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Location:
c'town, NSW
Registered:
May 2002
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Re: 4A: G vs F heads
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Fri, 22 October 2004 00:09
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go read bills website www.billzilla.org it explains it all there
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I Supported Toymods
Location:
south Melbourne/KL
Registered:
June 2004
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Re: 4A: G vs F heads
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Fri, 22 October 2004 02:26
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| rob_RA40 wrote on Fri, 22 October 2004 10:09 |
go read bills website www.billzilla.org it explains it all there
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yes he did!! he IS asking about something frm bill's website!!
Can somebody get biill over here??!?
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: 4A: G vs F heads
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Fri, 22 October 2004 04:01
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The good head is off a 7AFE, though I'm not sure which one and they're hard to find as well.
They still need a fair bit of work to be really good, but at the end of the day I reckon they'll crap all over any G head no probs at all.
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Location:
c'town, NSW
Registered:
May 2002
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Re: 4A: G vs F heads
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Fri, 22 October 2004 04:51
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| b1gb3n wrote on Fri, 22 October 2004 12:26 |
| rob_RA40 wrote on Fri, 22 October 2004 10:09 |
go read bills website www.billzilla.org it explains it all there
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yes he did!! he IS asking about something frm bill's website!!
Can somebody get biill over here??!?
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| Henn wrote on Thu, 21 October 2004 23:47 |
I just read a post by Bill Sherwood recently:
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this reads like a "post" on a forum
its easy to confuse, i was just trying to help, best to keep your knickers on darling else they get into a twist...
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Location:
cambo
Registered:
May 2002
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Re: 4A: G vs F heads
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Fri, 22 October 2004 06:15
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yes i was under the impression that G is wide angle head and F is narrow, and i was under the impression that that was where the power was from but i remember bill sherwood telling me a couple a years back that a narrow angled head has more potential for power? i still dont understand how/why.
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I Supported Toymods
Location:
south Melbourne/KL
Registered:
June 2004
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Re: 4A: G vs F heads
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Fri, 22 October 2004 06:15
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| rob_RA40 wrote on Fri, 22 October 2004 14:51 |
| b1gb3n wrote on Fri, 22 October 2004 12:26 |
| rob_RA40 wrote on Fri, 22 October 2004 10:09 |
go read bills website www.billzilla.org it explains it all there
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yes he did!! he IS asking about something frm bill's website!!
Can somebody get biill over here??!?
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| Henn wrote on Thu, 21 October 2004 23:47 |
I just read a post by Bill Sherwood recently:
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this reads like a "post" on a forum
its easy to confuse, i was just trying to help, best to keep your knickers on darling else they get into a twist...
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ooppss... my bad
so a 4af head can fit on a ae92 block??
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I supported Toymods
Location:
Perth, WA
Registered:
May 2003
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Re: 4A: G vs F heads
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Fri, 22 October 2004 06:19
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yes it does
but you have to search around for the right F head
theres a few different types and the one you want is very hard to find
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Location:
ghetto area 2745
Registered:
November 2003
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Re: 4A: G vs F heads
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Fri, 22 October 2004 06:41
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is this a common conversion 
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Location:
macca fields
Registered:
October 2004
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Re: 4A: G vs F heads
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Fri, 22 October 2004 10:51
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the g is for wide and the f is for narrow, i think the reason for the f head to be better is for air flow into the head is alot faster then that of a g head becuase of the angle of the valve
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Location:
Adelaide
Registered:
April 2003
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Re: 4A: G vs F heads
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Fri, 22 October 2004 11:41
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Er... I'd swap my F head with someone else's G head gladly!
I think that F head's flow have better midrange and have limited flow rates at higher revs. I don't know about the 1uz-fe but most F heads I've seen redline around 6250 rpms. Also with my car I notice power drops above 5500 rpms (4afe.)
G heads on the other hand flow better at higher revs but at the compromise of slower flow rates at lower rpms.
Torque in a 4afe is achieved 140Nm@4400rpm and 147Nm@6000rpm with the 4age. The 4afe reaches peak torque much earlier which suggests that it flows better at lower revs.
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Location:
Rosanna, Melb
Registered:
June 2002
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Re: 4A: G vs F heads
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Fri, 22 October 2004 13:34
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Yes that quote was taken from a post of Bill's on here. And I had a brief look round the billzilla site but couldn't find any info relevant to exactly this. Sounds like I should take another look when I have more time.
But is it essentially that the 7AFE head with alot of work can be made better than a 4AGE head with alot of work?
Sounds like something interesting to look into.
Hen
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: 4A: G vs F heads
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Fri, 22 October 2004 14:16
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| Henn wrote on Fri, 22 October 2004 23:34 |
Yes that quote was taken from a post of Bill's on here. And I had a brief look round the billzilla site but couldn't find any info relevant to exactly this.
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Try here -> Starlet engine page.
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Location:
Rosanna, Melb
Registered:
June 2002
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Re: 4A: G vs F heads
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Fri, 22 October 2004 15:13
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Thanks Bill.
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Location:
Adelaide, Semaphore
Registered:
September 2004
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Location:
brisvegas
Registered:
August 2004
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Re: 4A: G vs F heads
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Mon, 25 October 2004 03:03
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i heard along the grapevine that the F heads are better for turbo applications..something about the steep valve angle and the short port legth works well with it..very responsive..have a look at the starlet 4E-FTE..i haven't heard of a 4E-GTE..toyota must have done some reaserch into this..and developed that head for a reason..it might fall into the catagory of less that 45 deg between valves, but buy no means is it a economical grandmas car!
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I Supported Toymods
Location:
south Melbourne/KL
Registered:
June 2004
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Re: 4A: G vs F heads
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Mon, 25 October 2004 07:53
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| drift86levin wrote on Mon, 25 October 2004 13:03 |
i heard along the grapevine that the F heads are better for turbo applications..something about the steep valve angle and the short port legth works well with it..very responsive..have a look at the starlet 4E-FTE..i haven't heard of a 4E-GTE..toyota must have done some reaserch into this..and developed that head for a reason..it might fall into the catagory of less that 45 deg between valves, but buy no means is it a economical grandmas car!
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now we know y toyota doesnt produce 4aGte!!
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Location:
ghetto area 2745
Registered:
November 2003
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Re: 4A: G vs F heads
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Mon, 25 October 2004 09:23
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if f series heads are better why are they not used in motorsport as much as g heads as the cost wouldnt be much more as the price of work to them would be the same??
just curious.........
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: 4A: G vs F heads
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Mon, 25 October 2004 10:09
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| SEXY 16 wrote on Mon, 25 October 2004 19:23 |
if f series heads are better why are they not used in motorsport as much as g heads as the cost wouldnt be much more as the price of work to them would be the same??
just curious.........
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I've seen a few Formula One heads, take a guess what that good 7AFE head I have looks a lot like?
That style of head & port is used in a lot of purpose-built racing engines, FWIW. Take a look at a lot of Cosworth engines, for example.
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Location:
ghetto area 2745
Registered:
November 2003
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Re: 4A: G vs F heads
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Mon, 25 October 2004 21:27
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in the uk and ireland where rallying is huge the 1600cc class is all 4ages fully worked and this conversion is unheard of
i would like specs on the buggy in hollands engine
its sounds intersting!
curious to know is he running carbies or t/bodies and what the cost of the finished motor is roughtly
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Location:
Sydney, OZ
Registered:
May 2002
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Re: 4A: G vs F heads
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Tue, 26 October 2004 02:27
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[QUOTE]And what needs to be done to it to make this big power?/QUOTE]
Ports, valve sizing, and combustion camber mods ->matched to pistons, Good cams, Scissor cam conversion and piss off the crappy little throttle body-> Something rallying doesn't let me do and this always has held the power back.
I haven't seen Bill's page in a while, but it covers just about all I can say that can be done( something That I should of done yonks back)... The Head Bill does have is the late model series two from the AE102-AE111 OZ spec, the AE93 seca's are the one's you don't want.
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if f series heads are better why are they not used in motorsport as much as g heads as the cost wouldnt be much more as the price of work to them would be the same??
just curious.........
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Advantages of the G series head, Everything that can be done has been done and is available off the shelf. F heads are not, Everything That has been done to mine had to be custom made, 80% by me, the rest by others, so more or less the G series are cheaper to build, this I do know.
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theres a few different types and the one you want is very hard to find
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Not really now, you just need to know where to look and actually the last one I got was from one of the guys off this forum... Anyway I having a clean up soon and this is only a few...
 All are either the T-vis Import type or are AE102-AE111, Rallying controls us into what heads We're allowed to run.
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: 4A: G vs F heads
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Tue, 26 October 2004 02:57
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The 7AFE TVIS head isn't the really good one, it's the single port one.
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Location:
Melbourne
Registered:
November 2003
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Re: 4A: G vs F heads
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Tue, 26 October 2004 03:02
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As I understand it, and I'm just getting this off of Bill's site, a close angle head is better as you can have higher compression pistons without needing to dome the top of the piston (as much?). That's at least one reason.
As for Toyota F series heads, aren't they usualy economy heads? So wouldn't they have smaller valves for more torque, and completely different cams/tuning/parts all for low revs? So you would have to change a lot more about them to get any performance.
The next question is, why did Toyota go with wide angle heads for performance applications in the first place? It's probably a technology thing, but perhaps someone else on here can clear it up.
Err, Bill?
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Location:
Brisbane
Registered:
May 2002
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Re: 4A: G vs F heads
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Tue, 26 October 2004 03:33
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You might want to ask Yamaha that question... they seem to be a big fan of wide valve angles, and the heads they designed for Toyota reflect that. Have a look at an 18R-G head one day, talk about wide!
This was in the 70's though, so I guess times have changed since then.
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: 4A: G vs F heads
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Tue, 26 October 2004 03:42
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| Shraka wrote on Tue, 26 October 2004 13:02 |
As I understand it, and I'm just getting this off of Bill's site, a close angle head is better as you can have higher compression pistons without needing to dome the top of the piston (as much?). That's at least one reason.
As for Toyota F series heads, aren't they usualy economy heads? So wouldn't they have smaller valves for more torque, and completely different cams/tuning/parts all for low revs? So you would have to change a lot more about them to get any performance.
The next question is, why did Toyota go with wide angle heads for performance applications in the first place? It's probably a technology thing, but perhaps someone else on here can clear it up.
Err, Bill?
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Yes, a shallower valve angle means a smaller chamber (34cc on the F heads) and so a smaller done on the piston. Small, or no domes are best for flame propogation.
The valves in the 7AF heads are the same size as the G heads, 30.5mm and 25mm. I'm going to be using 32.5mm and 27.5mm though.
I don't know the reason for the last question sorry ... though ...
| Norbie wrote on Tue, 26 October 2004 13:33 |
You might want to ask Yamaha that question... they seem to be a big fan of wide valve angles, and the heads they designed for Toyota reflect that. Have a look at an 18R-G head one day, talk about wide!
This was in the 70's though, so I guess times have changed since then.
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.... I've never been impressed with any Yamaha head. Either the ports are too big, wrong shape, or just fundamentally wrong in some important way.
The gen4/5 3SGe heads aren't too bad though.
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Location:
Montrose, VIC
Registered:
May 2002
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Re: 4A: G vs F heads
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Tue, 26 October 2004 04:15
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Would it be partly to do with having enough room for the cam sprockets to fit alongside each other? Now you've got me intrigued about something though... How similiar is the 7AF and 4AG exhaust manifold pattern?
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Location:
Melbourne
Registered:
November 2003
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Re: 4A: G vs F heads
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Tue, 26 October 2004 04:53
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| mrshin wrote on Tue, 26 October 2004 14:15 |
Would it be partly to do with having enough room for the cam sprockets to fit alongside each other?
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If I understand what you are talking about, then this is why the SR20DE uses rockers. That way they can keep their cames spaced appart, while still having a narrow angle head.
I'm wondering if a wide angle head is much of a problem for turbocharged engines, where you desire a low compression. As you don't have to worry about high compression, can you just make your piston flat even with a wide angled head? Does the head being angled effect flame propogation in of itself? Or is it just piston dome that is the problem?
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I Supported Toymods
Location:
south Melbourne/KL
Registered:
June 2004
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Re: 4A: G vs F heads
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Tue, 26 October 2004 05:04
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head being angled affects how to combustion goes. This technology came about in the honda CRX (not sure wich yr). It produced more power and thats y most cars have angled heads later on
Im talking about the top of the combustion chamber, ie engine head. Are we talking bout the same thing??
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: 4A: G vs F heads
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Tue, 26 October 2004 05:04
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| mrshin wrote on Tue, 26 October 2004 14:15 |
Would it be partly to do with having enough room for the cam sprockets to fit alongside each other? Now you've got me intrigued about something though... How similiar is the 7AF and 4AG exhaust manifold pattern?
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The exhausts are totally different unfortunately. 
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Location:
Montrose, VIC
Registered:
May 2002
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Re: 4A: G vs F heads
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Tue, 26 October 2004 06:17
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Bugger... Oh well!
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: 4A: G vs F heads
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Tue, 26 October 2004 06:28
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| b1gb3n wrote on Tue, 26 October 2004 15:04 |
head being angled affects how to combustion goes. This technology came about in the honda CRX (not sure wich yr). It produced more power and thats y most cars have angled heads later on
Im talking about the top of the combustion chamber, ie engine head. Are we talking bout the same thing??
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Honda wasn't anywhere nearthe first. I know Keith Duckworth from Cosworth built the DFV V-8 F1 engine deliberatly with a narrow-valve head in 1967. There were no doubt others before that as well. 
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Location:
Melbourne
Registered:
November 2003
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Location:
Brisbane
Registered:
May 2002
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Re: 4A: G vs F heads
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Tue, 26 October 2004 06:51
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I think it depends on the combustion chamber type used. For example, the 18R-G has a hemispherical combustion chamber so a wide valve angle is going to work well with that. The 7A-FE has a pentroof CC I think? So to my simple way of thinking, a narrow angle is going to work better with that.
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Location:
Melbourne
Registered:
November 2003
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Re: 4A: G vs F heads
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Tue, 26 October 2004 07:25
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| Norbie wrote on Tue, 26 October 2004 16:51 |
I think it depends on the combustion chamber type used. For example, the 18R-G has a hemispherical combustion chamber so a wide valve angle is going to work well with that. The 7A-FE has a pentroof CC I think? So to my simple way of thinking, a narrow angle is going to work better with that.
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Yes, sorry I should have clarified. I was talking about the pentroof style chamber head, not the Hemi style head.
I'm trying to figure out why a Nissan SR20DET can produce as much power as a 3S-GTE. The 3S uses a wide angle head, and the SR20 goes so far as to have rockers to make the head angle narrow! Now understandably a narrow angle is desirable for high compression engines where the shape of the piston becomes an issue to increase compression, but I was wondering if it makes any difference in a low compression engine.
And I assume by the list of responses, nobody has any idea why Toyota went with the wide angle head? Or was it Yamaha?
Either way... wait, could it be that Yamaha's RnD all whent into making bikes? The angle of the head would have an effect of the height of the engine and thusly compromise packaging perhaps? I'm not saying Yamaha just threw a bike head onto the 4A-GE, but with all RnD focused in one area, it would cost a lot of money to deverge and make a good close angle head (I imagine). Though I'm probably way off.
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: 4A: G vs F heads
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Tue, 26 October 2004 07:53
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FWIW here's a pic of the 7AFE combustion chamber.
It's a pretty deep chamber and only a slight pentroof.
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Location:
Sydney, OZ
Registered:
May 2002
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Re: 4A: G vs F heads
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Tue, 26 October 2004 10:49
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The 7AFE TVIS head isn't the really good one, it's the single port one
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Yeah, the AE102 ie this one.
and not but this one.
 which is the AE9# 4AFE/FC. I can't say if it flows better or worse than this one,  the T-vis. Being of later design T-vis has the ports still higher than the FE/FC version, I would assume this would be better, and a lot more fun getting to flow with a die grinder.
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Location:
Montrose, VIC
Registered:
May 2002
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Re: 4A: G vs F heads
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Tue, 26 October 2004 14:17
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I'm certainly interested to see what the results are on the flowbench, and much more importantly, on the engine, with the 7AF head. Who knows what could start here 
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: 4A: G vs F heads
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Tue, 26 October 2004 14:27
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heh heh, what will start is another DoRifto rush for the next big thing last week was turbo 20V heads on 4AGZE blocks.. this week, single port 7AFE heads...
next week? LED lit gauges in air vents?
sigh....
is interesting to see the port angles tho.. wonder what made toyota chop and change so much on basically the same motor.... (could be said for 4AC-F-G too)
Cya, Stewart
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Location:
Montrose, VIC
Registered:
May 2002
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Re: 4A: G vs F heads
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Tue, 26 October 2004 14:36
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Let's start a rumour about 4AC heads 
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Location:
u.s.a. south
Registered:
April 2004
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Re: 4A: G vs F heads
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Tue, 26 October 2004 15:36
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I dunno why people get all hung up on head flow and hp numbers.
What does it translate to in 'real world' performance ?
What level of performance can u not attain with a 4agte, say in a rolla, that a F head will get u ? Not one bit, I'd bet.
Folks always drool over honda cylinder head design. Turbocharged, u see lopsided hp vs torque figures, even more dramatic than n.a. U can have 500hp 2.0L street cars with tq just over 300, or 600hp and 370tq, for example.... great if you're into bragging about your dyno sheets.
The only thing that buys you is extended rpm range... the high hp cars are NO faster than same weight, lower hp cars making the same tq (once geared right).... based on my everyday observations.
As renowned engine builder John Ligenfelter said, "nah, hp only sells motors, but tq will win u the race"
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I Supported Toymods
Location:
south Melbourne/KL
Registered:
June 2004
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Re: 4A: G vs F heads
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Tue, 26 October 2004 15:48
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| quest wrote on Wed, 27 October 2004 01:36 |
As renowned engine builder John Ligenfelter said, "nah, hp only sells motors, but tq will win u the race"
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true!!
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Location:
Sydney
Registered:
May 2003
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Re: 4A: G vs F heads
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Tue, 26 October 2004 15:50
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hm the way ive elarnt is hp equates to top speed whereas torque equates to acceleration...
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Location:
Sunbury, VIC
Registered:
November 2003
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Re: 4A: G vs F heads
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Tue, 26 October 2004 21:53
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| mrshin wrote on Wed, 27 October 2004 00:36 |
Let's start a rumour about 4AC heads
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Woohoo! There's hope for my 4A-C yet. LOL.
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Location:
Melbourne
Registered:
November 2003
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Re: 4A: G vs F heads
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Wed, 27 October 2004 00:08
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| quest wrote on Wed, 27 October 2004 01:36 |
As renowned engine builder John Ligenfelter said, "nah, hp only sells motors, but tq will win u the race"
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Then why do almost all race engines rev high? Hell, even big V8s rev out to.. what? 7500? 8000rpm? Why don't they use truck engines that rev out to 1000rpm and produce shitloads of torque if power doesn't matter?
Peak torque is fairly irelivent if you have correct gearing, as when you change your gearing, you change the torque at the wheels anyway. What you want is a nice flat powerband and then just set the gears up to sit in that, for circuit anyway. Dragracing is different, I imagine. So is road use.
And nobody has answered my question about the top of the combustion chamber in forced induction engines.
[Updated on: Wed, 27 October 2004 00:10]
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: 4A: G vs F heads
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Wed, 27 October 2004 01:49
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| Shraka wrote on Wed, 27 October 2004 10:08 |
| quest wrote on Wed, 27 October 2004 01:36 |
As renowned engine builder John Ligenfelter said, "nah, hp only sells motors, but tq will win u the race"
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Then why do almost all race engines rev high? Hell, even big V8s rev out to.. what? 7500? 8000rpm? Why don't they use truck engines that rev out to 1000rpm and produce shitloads of torque if power doesn't matter?
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Because with more revs - even with no more torque - you can run a shorter diff ratio and so make more torque at the wheels, so the car accelerates faster.
E.G. F1 cars. The engines today hardly make any more torque at the flywheel than they did in the late 1960's. They also don't have a top speed a great deal higher either.
However, instead of the 11,000rpm odd they used to run at, they're now at 19,000rpm and so are making about 72% more torque at the wheels. That's one reason why they're so much faster than before.
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Location:
Melbourne
Registered:
November 2003
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Location:
u.s.a. south
Registered:
April 2004
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Re: 4A: G vs F heads
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Wed, 27 October 2004 06:30
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rpm and gearing all factor into the equation, yes.
I'm saying engine torque vs vehicle weight gives u a better picture of a cars acceleration potential.
Look at the 160hp 1.6L Honda del sol. Critics raved about the 100hp per liter. ok, yet it still only made the same 112 ft-lbs of torque as the mr2 4ag. The cars weigh roughly the same and has nearly identical performance figures. How come ? Hp tells us it shouldn't be close, eh ?
Take a honda s2000 240hp 2L powerplant. Called a "technological marvel". Ever heard of a Buick GN ? Weighs ~3400+ pounds, powered by a 3.8L v6 that makes a 'measly' 245hp... BUT 340 ft-lbs of torque vs the honda 130 or so. Put the honda motor in the Buick, gear it the best u possibly could and you still won't come anywhere near the 3.8's acceleration figures... and its not the 5hp advantage either. Get it?
I can't answer the pentroof design question - I normally don't look the deep into stuff.
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Location:
Rosanna, Melb
Registered:
June 2002
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Re: 4A: G vs F heads
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Wed, 27 October 2004 06:58
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This was more posed as a theoretical question.
Sure, you can argue about whether it is worth the hassle doing an F head swap onto a 4AGE, but it sounds like there is some advantage to be had. And for the guys at the really pointy end who know what they are doing, like Johnny and Bill, it may be worth it.
In any case I now need to go and do a bunch of reading about port design, squish areas, piston profiles etc etc...
Hen
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Location:
u.s.a. south
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April 2004
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Re: 4A: G vs F heads
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Wed, 27 October 2004 06:59
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oh, ....and few can touch Ligenfelter performance credentials.
I still have an article where some of the worlds elite tuners flew in their offerings to a common proving ground in the u.s. for a showdown. A corvette, powered by an unassisted, lowly pushrod v8, emerged the victor in ALL acceleration catagories, over many multivalved, boosted and nitrosed powerplants. To add insult to injury, the vette was the only car that conducted all its tests with a passenger AND had the airconditioner on throughout! Guess who built *that* corvette ?
>>"Why don't they use truck engines that rev out to 1000rpm and produce shitloads of torque if power doesn't matter?"
I guess you didn't know thats exactly what some folks are doing.
Ever see a daily driven 'duallie" heavy duty diesel pickup smoke its 4 rear tires down the entire quarter mile ? ...pull up to the line, turn the boost DOWN, then run a low 11sec ET ? They weigh close to 7000 pounds and have relatively low hp rating. Any idea where this magic comes from ?
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Location:
u.s.a. south
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April 2004
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Re: 4A: G vs F heads
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Wed, 27 October 2004 07:21
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sorry Henn,
I understand what you're saying, but I'm the type that will sit back and observe what the "F" heads are doing, if I were that curious. I wouldn't wanna be a guinea pig.
The F series may've been launched purely for economic reasons or even space saving, who knows.
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Location:
Melbourne
Registered:
November 2003
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Re: 4A: G vs F heads
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Wed, 27 October 2004 07:31
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Yesss, I had a feeling you where talking about dragracing.
If torque is so important to circuit work, and power is not, why do even the V8 'supercars' rev out so high?
And you do know that torque is power / rpm, right?
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: 4A: G vs F heads
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Wed, 27 October 2004 07:34
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| quest wrote on Wed, 27 October 2004 16:59 |
I guess you didn't know thats exactly what some folks are doing.
Ever see a daily driven 'duallie" heavy duty diesel pickup smoke its 4 rear tires down the entire quarter mile ? ...pull up to the line, turn the boost DOWN, then run a low 11sec ET ? They weigh close to 7000 pounds and have relatively low hp rating. Any idea where this magic comes from ?
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because it's american, and a V10 powered pickup is king of the road...
the power vs torque thread has been done to death a few times..
let it die.
and from online ET calculators,
7000lb to get 11sec 1/4 needs around 1200hp
so you are saying they turn down the boost and get 1200hp??
what capacity are we talking here??
Cya, Stewart
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Location:
Adelaide
Registered:
May 2003
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Re: 4A: G vs F heads
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Wed, 27 October 2004 07:58
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From what i understand it the Yamaha G heads have a hugely wide valve angle in order NOT to use rockers. So far as i can figure, my 4AGE has similar properties to my old R6. As in they both rev like buggery.
So if we go off the theory that Yamaha were developing the G series heads along the same design principles as their R* series bikes they woudl be developing them for high flow at high rpm, and not caring much about torque, because as Shraka has said torque changes as per RPM. This is how race bikes are designed. Now if they are developing for say a peak power at 7000rpm (4AGE) they would want as few reciprocating parts as possible, especially ones with large inertial mass actuated off the camshafts.... i.e. rockers. So they went to a shim/bucket design. Shim and buckets take up room, and hence the wide angles on the valves. This allows the engine to rev to higher rpm without large amounts of damage to the rockers.
Now if we look at our rocker engine, namely the SR20 we can see that it makes peak power further down in the range at around 5500rpm, rather than the screaming 7000rpm which Yamaha have designed their head for. This is largely due to the rocker design in the head (or lash adjusters as they call them). And we notice that the CA18 which doesnt have lash adjusters can rev a lot higher 7200ish rpm. When people are building a high rpm and high power SR20 engine the main thing which is replaced are the lash adjusters/rockers. And not at any cheap cost either might i add. But the advantage is a narrow valve angle.
How else can we get this narrow valve angle, well by using shim/bucket design but changing the cams to drive each other off the single camgear. Now this is a fairly good design, as you dont have any pesky rockers to get in the way of high rpm, but by the same token you also dont have the adjustment in the cam timing. Lets put that aside for the time being, and work on just the rpm. I think i can safely assume that one the F head's great limitations is not contained within the head, but rather within the engine itself. i.e. the static compression. The other problem i can see is with the airflow within the head, and so i guess it may be a combination of these.
I think thats about it. Ive kind of tried to get into the heads of the designers and think about it from a completely seperate standpoint.
As for the GZE i think that came about due to some development designs being thrown into production without being perfected. I think the best evidence of this can be seen in the design of the intake into and exhaust from the supercharger.
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Location:
u.s.a. south
Registered:
April 2004
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Re: 4A: G vs F heads
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Wed, 27 October 2004 14:32
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yes, I'm primarily talking about acceleration.
I can't do a better job of explaining it as I have already. I thought I gave pretty clear examples..... guess not, huh.
Diesel truck performance have come a long way, and they have "bump up" bolt-on kits that introduce the average customer to more tire shredding torque than they know what to do with. I did not commit the exact particulars of the truck to memory, but I know there are various turbo deisel powerplants (not v10) well capable of 'performance car' ETs. I think there is a video or 2 of such beasts online iirc.
Tell u what, plug the mr2 and del sol hp numbers in your "online ET calculators" and see what u come up with.
Stick with "formulas" and they'll lead you astray. Same with hp 'figures' and head flow 'numbers'. Thats the only point I'm trying to make.
....back to G vs F head
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: 4A: G vs F heads
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Wed, 27 October 2004 15:08
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these are the commonly available "ET calculators" that give a rough HP number needed to get a certain ET for a certain weight, and they are reasonably accurate..
the thing is.. to move a given mass a given distance (400m) in a given time (11sec), you have to expend a certain amount of energy. expending that energy in a given time frame is POWER.
show me a 7000lb vehicle that does 11 seconds on the 1/4 with less than 1000hp and i'll be very amused
as was said in the power vs torque thread, there's no point having huge torque if it isn't moving quickly (ie 50,000Nm water wheel)
i'm not saying diesels or trucks are not fast (our own "super trucks" are astonishing!!, racing prime movers with massive hp, which, since they are diesel and have limited rpm, means HUGE torque, and they are fast http://truckracing.com.au/ )
http://www.inky.co.nz/
| Quote: |
Displacement: 12 litre, 6 cylinder, Bore 130mm Stroke 150mm
Twin Schwitzer Turbochargers, running speed 175,000 RPM
Boost: 61 PSI
The Freightliner: engine develops in excess of 1500 bhp @ 2500 RPM and 4200 ft lbs of torque.
The Freightliner in race trim weighs 5500 kg
Approximate standing 1/4 mile time, 13 seconds
160 km/h in 12 seconds
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the ET calcs predict (for this 12100lb monstor) 12.3 seconds.. given that it is restricted in top speed, and has massive traction problems, it's not far fetched.
to do an 11.0, it would need around 2200hp...
anyway, wtf do US pickups have to do with F vs G heads anyway....
i'd like to see one do the drifting Inky Tulloch does
now THIS is a truck.. but it still doesn't have an F or G head
http://www.bandagbullet.com/
[Updated on: Wed, 27 October 2004 15:16]
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: 4A: G vs F heads
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Wed, 27 October 2004 15:22
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| quest wrote on Wed, 27 October 2004 01:36 |
the high hp cars are NO faster than same weight, lower hp cars making the same tq (once geared right).... based on my everyday observations.
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wanna try that again, backed up by maths we did this derivation before. same power = same time if geared correctly. different power = different time.
everday observations.. humph...
Cya, Stewart
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Location:
Adelaide
Registered:
May 2003
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Re: 4A: G vs F heads
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Wed, 27 October 2004 21:52
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| drift86levin wrote on Mon, 25 October 2004 13:03 |
i heard along the grapevine that the F heads are better for turbo applications..something about the steep valve angle and the short port legth works well with it..very responsive..have a look at the starlet 4E-FTE..i haven't heard of a 4E-GTE..toyota must have done some reaserch into this..and developed that head for a reason..it might fall into the catagory of less that 45 deg between valves, but buy no means is it a economical grandmas car!
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Now here is something i meant to reply to last night. I dont think that the 4E-FTE came about through some huge amount of research and development from Toyota, but rather through slapping a turbo on an already existing engine (4E-FE). Same as the ubiquitous 4A-GZE it was a development on an already existing engine design. If you look at the cutouts on the GZE pistons compared to the GE pistons you can see that they are completely flat apart from minor cutouts in the piston. I think this is to compensate for the valve angle for proper flame propogation. Although i honestly dont think it matters so much for the applications which Toyota wanted these for. I doubt much R&D has gone into the 4A-GZE and the 4E-FTE and rather they were created as Toyota wanted supercharged and turbocharged cars in their lower end lineup.
I am guessing there must be some rhyme and reason behind the HUGE number of R&D hours which have gone into the 3S-GTE and 2JZ-GTE engines, especially when they are used in JGTC format. Why didnt they go to F heads on these engines, especially when the power is at a premium. I mean they already spend tens of millions on custom parts for these engines, so why not slap an F head on them if it is more efficient. Somehow i think that it isnt more efficient, and rather the G head provides an advantage somehow.
Now as for what that advantage is i think i have a bit of a clue. From driving both my 4AGE and my dad's 4AFE i think the advantage lies in the RPM range which the engine provides power, as i alluded to in my first "essay". With an F head the flow and flame characteristics would probably limit the power and torque band much more narrowly. Wheras the G heads have a repeatedly shown wide power band, which for the 4AGE starts from around 4500 and goes to 7500rpm in stock configuration. This wide power band of the G head woudl give drivers an advantage over those who had a narrow power band of the F head, mainly because of gear changes. Even if an F head flows signficantly more over 1000rpm and produces more power there, the gearing would need to be set up so closely for that 1000rpm that the driver woudl be changing gears every couple of seconds. However, for the G head given a 3000rpm power band in stock configuration (commonly 2500rpm in modified) this gives a much longer time in each gear, and therefore removes one of the slowest parts of racing, gearchanging.
Now you say, why dont they just go to a flatshift type antilag system, or something similar. Well i woudl guess that the regs would get in the way, and they woudlnt be allowed. Just like i cant add a flatshift system and still stay in Supersprint
Comments?
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I Supported Toymods
Location:
Wollongong, NSW
Registered:
December 2003
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Re: 4A: G vs F heads
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Wed, 27 October 2004 23:26
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Getting back to the 7A-FE heads thing.... would it be worth shelling out dollars to strengthen and turbocharge a 7A-FE vs. the 4A-GZE --> 4A-GTE route?
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Location:
Sydney, OZ
Registered:
May 2002
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Re: 4A: G vs F heads
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Thu, 28 October 2004 00:48
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| Quote: |
Getting back to the 7A-FE heads thing.... would it be worth shelling out dollars to strengthen and turbocharge a 7A-FE vs. the 4A-GZE --> 4A-GTE route?
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Again, parts are readily available for the GZE,ie I can just walk into many places and ask A/M parts for a 4AGE/GZE and most can get them in a few hours to a day at most.... Not the 7AFE, it's just a matter of your time and effort in finding good replacements that may be a straight swap or may have to be modified... The pistons I use were just a set of 4AGE blanks I managed to chase up, Then I had machined to suit... And Really I had no options but to develop the 7AFE due to the rally regs,up till now, which now allow 20V's to be fitted to my car. Yes a 20V will live in my new one, but the old one, I'm still questioning what way I should go, I have spent way too much so far on this and I don't want to spend any more and rather put this cash into developing the new car for F16... The old one is F2 and we get ZERO coveraged these days....
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