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Location:
Newcastle
Registered:
May 2002
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Banned member
Location:
Brisbane
Registered:
May 2002
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Re: 3tg manifolds on 2tg head
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Mon, 13 January 2003 07:57
 
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the exhaust manifold will bolt straight up but the intake is a different pattern !
a 2tg head does flow a lot better than a 3tg-gte head and i have been told 2tg cams arent as tame as the 3tg being they are made for a turbo, but if you do swap remember the distributor is different !!
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Location:
Canberra
Registered:
May 2002
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Re: 3tg manifolds on 2tg head
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Mon, 13 January 2003 10:23
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I'm still yet to see proven results that the 2TG head is that much better flowing.... I've brought it up a couple of times b4 and got no real answer, it seems 3rd hand info most of the time.
It is easier to fabricate intercooler plumbing with the 2TG's forward facing throttle body, and there are a heap more cam grinds available, but if you already have cams, i'd use the 3TG head!
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Location:
Colac, Victoria
Registered:
May 2002
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Re: 3tg manifolds on 2tg head
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Mon, 13 January 2003 11:45
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Ive heard that good old 2t heads ( single cam ) flow even better again - dunno if its true or not
- but id be keen to know !
im having my 2tB head bench flow tested when the cam goes in - ill try and get printouts on figures - since its a worked one .
Ask rod try - he's got some good theorys on head flows for 2t, 2tg and others 
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Location:
Brisbane
Registered:
May 2002
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Re: 3tg manifolds on 2tg head
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Tue, 14 January 2003 00:01
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Does anyone know the valve sizes for these engines? I'm almost certain the later model 2T-G's have much larger valves than the 3T-GTE, but I can't seem to find any exact specs...
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Location:
Colac, Victoria
Registered:
May 2002
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Re: 3tg manifolds on 2tg head
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Tue, 14 January 2003 00:14
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original 2tg carby heads i believe are the ones with the larger hvalve size - also early model 2t's and 2tb's have larger vlaves too from what ive read ..
Dunno if my 2tb is a newer or an older - but the valves are bigger than the bare 2t head i have in the shed
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Banned member
Location:
Brisbane
Registered:
May 2002
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Re: 3tg manifolds on 2tg head
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Tue, 14 January 2003 06:56
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hey stu didnt you buy your motor 2nd hand with work already done to it ?
and wouldnt you know it, i have a genuine toyota 2t, 3t, and 2tg engine manual here and it dosnt tell me shit about valve sizes only the length
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Location:
Canberra
Registered:
May 2002
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Re: 3tg manifolds on 2tg head
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Tue, 14 January 2003 07:17
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just measured a couple of 3TG valves in my garage, inlet 44mm, exhaust 38mm
Phil
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Location:
Newcastle
Registered:
May 2002
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Re: 3tg manifolds on 2tg head
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Tue, 14 January 2003 07:42
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The cams I have are actually for a 2TG engine but these fit the 3TG head. As for the inlet manifold I was only going to keep the bottom half and fabricate a forward facing one with a XF throttle body. I just wanted to know if this would bolt onto the 2TG head of if I would need the 2TG mainfold. I will not be running a distributor with this engine so that is not an issue. I was going to get the 3TG head ported and shimmed to suit the cams and wanted to know if there really was much differnce in flow rates.
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Banned member
Location:
Brisbane
Registered:
May 2002
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Re: 3tg manifolds on 2tg head (which one flows better)
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Tue, 14 January 2003 08:12
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id be asking rod try he is the guru here and has the flow sheets !
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Location:
Colac, Victoria
Registered:
May 2002
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Re: 3tg manifolds on 2tg head
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Wed, 15 January 2003 11:02
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The motor was a fresh rebuild .. hadmnt been turned over in a car when i got it - just ran an engine dyno for testing ..
and yes - it had most of the work done to it bar induction and extraction and dizzy mapping
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Club President
I supported Toymods
Location:
Sydney
Registered:
May 2002
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 Re: 3tg manifolds on 2tg head (which one flows better, attn rod)
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Thu, 16 January 2003 00:58
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OK... Talk about a can of worms so I'll split it up a bit !
CAMS.
Firstly 2TG and 3TG cams will interchange ! So any cam grind you can get for a 2TG will fit in a 3T-GTE.
The reason there are more grinds for the 2TG is that not many people play with the cams in the 3T-GTE, Turbo performance is relativly new when compared to N/A performance !
Then you have to consider that in a N/A engine the cam does all the work as far as dictating how much air gets into the head. (Valve size and ports aside) With a Forced induction engine the Turbo jams it in there so the cams are generally paid alot less attention.
A Turbo's cams also use a whole different set of rule as depending on your desired result Overlap is not such a good thing !
VALVES
Ok excluding the 11111-88220 head the 2TG's and 3T-GTE's have the same size valves ! The first version of 2TG head (88220) has smaller valves on both the inlet and exhaust.
2TG Valve Size: Intake - 43mm (Up to April 1973) (88220 Head)
- 44.5mm (April 1973 Onwards)
Exhaust - 37mm (Up to April 1973) (88220 Head)
- 38.5mm (April 1973 Onwards)
HEAD FLOWS
Ok Head flow is ONE of the more important characteristics of a head. But it isn't everything. You also need to consider the chamber design, Sqish area's, the actual flow direction and turbulence, the placement of the spark plug or plugs, Airspeed and probably a dozen other things I have no idea about.
The second thing to remember is the cams will dictate just how much air gets in. Headflow figures are measured at certain lift points of the valve. If your cams only give you 300 tho lift then there is no point worrying about what happens inside the head when you have 400 tho Lift as the cams don't get there !
I for example had my head rebuilt to suit the engine I am building. It was flowed and the cams were made to accomadate the figures we acheived. In turn the intake manifold and Throttlebody needs to meet the same flow requirements or its all a waste of time.
2TG v's 3TGTE
To be honest I can't answer which one is best ! There is still so much I haven't had the time or money to test ! The heads use a different port design and both work very well in there designed applications. In stock form the cams and intake manifolds limit the engine opperation long before the heads do.
If you take the cams and manifold out of the equation then in stock form you can make a base line comparison. I used a 88261 EFI 2TG head (As per my engine build) And yes it does perform better than a 3T-GTE Head flow wise how much better varies at each lift point.
As for chamber design and squish areas etc. The 3T-GTE head is apparently a better design. I am not really able to offer an opinion on that as it is too far out of my ability and learning.
BUT
Before you all go ditching your 3T-GTE heads bring it all back into context ! You only need the head to flow as well as your cams and intake manifold can support ! You also need to remember that an intake manifold can not only restict but increase the airflow thru a bare head. A well designed intake manifold will channel in more air than a bare head will flow alone (Even on a flow bench when the air is being channeled)
Then there is the ancient mystical voodoo art of head porting ! I can only evaluate the performance of my Personal 2TG head. I am still trying to obtain a well ported 3T-GTE head for comparison. Given the 3T-GTE's better chamber design then it would be desireable for a ported 3T-GTE head to outflow a Ported 2TG head. I honestly have no idea if it will but I have never seen Toyota, TRD or TTE use a Turbo 2TG head !
Also a mild port job on a 3T-GTE will generally cost less than fitting a 2TG head.
Classique 71,
Mate Head flow figures should be treated like Dyno Figures in my opinion. They need to be from the same machine at the very least. Different places take varying levels of care in ensureing there machines are calibrated correctly. There is also quit a technique to getting it right.
That being said I'd love to see your head flow figues when you get them. Can you find out if it is measured at 28 Inches of Mercury and of course the lift points for each value.
Hope that helps !
[Updated on: Thu, 16 January 2003 01:01]
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Location:
Newcastle
Registered:
May 2002
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Location:
Brisbane
Registered:
May 2002
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Re: 3tg manifolds on 2tg head (which one flows better, attn rod)
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Thu, 16 January 2003 02:57
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[quote
Rod: Why is it cheaper to port a 3TG head?[/quote]
I think he was talking about it would be cheaper to port a 3TG head than to fit a 2TG head (to make the 3TG flow as well as the 2TG). I would think the cost would be close to the same.
Cheers
Wilbo
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Club President
I supported Toymods
Location:
Sydney
Registered:
May 2002
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Re: 3tg manifolds on 2tg head (which one flows better, attn rod)
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Thu, 16 January 2003 03:47
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Thats exactly what I meant Wilbo666,
The 2TG heads are of course getting pretty old now and while they can be bought fairly cheaply (If your lucky ) They generally need to be rebuilt. Every one I have bought has had either slightly bent valves  Or the engine has been regulary over reved and the Valves get tuliped from slamming back into the head 
Either option means you have to fit a new head gasket etc etc but a mild port job on a 3T-GTE would/should be cheaper than reconditioning a 2TG head.
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Registered:
May 2002
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Re: 3tg manifolds on 2tg head (which one flows better, attn rod)
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Wed, 08 December 2004 04:55
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I can speak from experience that the manifold design can definitely affect the flow of a standard 2TGEU. I used a system where the air is rammed into the head and i gained a generous 30rwkw and a much higher rev range and the torque curve impressed the dyno tuner too.
Tuning is important and matching is VERY important too. As Rod has mentioned, there's no point doing up one thing if you're not prepared to match it up every where else round the motor.
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Registered:
May 2002
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Re: 3tg manifolds on 2tg head (which one flows better, attn rod)
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Wed, 08 December 2004 04:57
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Shit! I just realised this thread is 20 years old.
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Location:
Perth,western australia
Registered:
December 2003
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Re: 3tg manifolds on 2tg head (which one flows better, attn rod)
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Wed, 08 December 2004 06:16
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got any pics of that intake design??
id very much liek to see it.
cheers
Dom
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Location:
Dandenong Ranges, VIC
Registered:
July 2004
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Re: 3tg manifolds on 2tg head (which one flows better, attn rod)
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Wed, 08 December 2004 09:00
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what he said!
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Registered:
May 2002
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Re: 3tg manifolds on 2tg head (which one flows better, attn rod)
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Wed, 08 December 2004 22:31
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Well i don't want to give away too many secrets but I'm less likely to build a monster 2TG motor as what i have in mind will cost a fair bit.
Well... if you talk to any of the competition drags guys who raced in strict classes in the 70's, they had to find power without boring or using extremely larger cams, etc. So they found power in high flowing their heads. One secret was to develop a ram effect within the manifold into the inlet ports (causing a similar effect as a force fed induction).
When i bought the standard efi setup and saw this ridiculous 50mm throttle body, i thought to myself, "how can this pea shooter suck more air than the 4x 40mm inlets on my solex's?". So i ditched the whole setup and sourced myself some efi quad throttle bodies (QTB). The intake on these were huge (too huge actually and i was told that my low compression motor wouldn't accept them at all and that it'll run like a dog). But i begged to differ so i installed it all myself.
I match ported the original twin carb manifold to the QTB and matched the inlet side the the gasket as well. The porting was awesome as it was like a trumpet. When i got the Delco tuned, it made 30rwkw more than the carb's and red lined easily to 7000rpm rather than 5400rpm running the carbs. And did i forget to mention how much extra torque there was, farken yeah! The car was not only still drivable but a different beast with very high potential. Mind you the head and block are still standard.
I don't have any pics as it's not too pretty under there, as all you'll see is hoses and dirty metal.
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