| Author | Topic |
|---|
Location:
Lost in the K hole
Registered:
May 2002
|
 does it matter which way a throttle plate opens??
|
Mon, 04 October 2004 13:08
|
 |
as in title??
does it matter if the throttle plate opens one way or another?
ie, the top of plate rotates outwards opposite to the flow of incoming air, whilst the bottom of plate rotates inwards in the direction of the intake flow? (this is the *normal* direction of plate rotation i believe)
OR vice versa?? does it matter?
would the plate induce preferential flow to the bottom of the port (at part throttle) in the normally rotating plate? would i flip this preferential flow to the roof of the port of the throttle opened the opposite way??
does it matter? perhaps its would if the throtle is very close to the head and intake valve?
also - does it really matter if the heads of the fasteners attaching the throttle plate to the shaft sit outwards or inwards? normally the face out, i guess as a consequence of access in the even that they may loosen?? otherwise??
any issues i havent addressed?
cheers
ed
|
|
|
I supported Toymods
Location:
Australia
Registered:
November 2003
|
|
|
Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
|
|
|
Toymods Board Member
I supported Toymods
Location:
Turramurra, Sydney.
Registered:
May 2002
|
|
Re: does it matter which way a throttle plate opens??
|
Mon, 04 October 2004 14:32
|
|
One thing I noticed looking at the recent pics of the BMW V10, the port shaping is very much influenced by the direction the throttle opens.
How good is that, nice steep angle straight into the cylinder, & it couldn't be more than 150mm from the throttle to the back of the valve. 
|
|
|
Location:
Sydney
Registered:
May 2002
|
|
Re: does it matter which way a throttle plate opens??
|
Mon, 04 October 2004 23:54
|
|
I was told you want the blade opening inwards on whatever side has the shortest path to the valve. Apparently the air starts moving on that side of the port first and a higher percentage of the total air ends up flowing along that side.
The pic of the V10 seems to agree with the theory....
Darren.
|
|
|
Location:
Lost in the K hole
Registered:
May 2002
|
|
|
Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
|
|
Re: does it matter which way a throttle plate opens??
|
Tue, 05 October 2004 04:04
|
|
from a GSXR1000 (google search'images' for GSXR throttle)
i would so love that V10 intake on my 4K  sigh.. i can dream can't i? 
|
|
|
Location:
Adelaide
Registered:
May 2003
|
|
Re: does it matter which way a throttle plate opens??
|
Tue, 05 October 2004 04:08
|
|
That BMW engine will have some lovely air speed.
As for throttle actuation, the 20v ITBs normally actuate top in bottom out. I have flipped the throttles upside down as per what Darren has suggested. Im guessing it woudl be about 100-110mm from butterfly to the valve seat. Ill have to do some better measurements when i pull the head off.
Most FWD Toyotas open top in bottom out, wheras RWD have bottom in top out.
|
|
|
Location:
Lost in the K hole
Registered:
May 2002
|
|
Re: does it matter which way a throttle plate opens??
|
Tue, 05 October 2004 04:09
|
|
|
bizzare
|
|
|
Location:
South Australia
Registered:
July 2002
|
|
Re: does it matter which way a throttle plate opens??
|
Tue, 05 October 2004 07:23
|
|
| Quote: |
I was told you want the blade opening inwards on whatever side has the shortest path to the valve. Apparently the air starts moving on that side of the port first and a higher percentage of the total air ends up flowing along that side.
The pic of the V10 seems to agree with the theory....
|
Basically that's correct  Although I think the air speed on the outwards moving side would be greater, the volume flux would still be lower (lower pressure).
|
|
|
Location:
South Australia
Registered:
July 2002
|
|
Re: does it matter which way a throttle plate opens??
|
Tue, 05 October 2004 07:33
|
|
|
Actually - when I think about it...it won't make much difference to the over-all power, or even the torque curve, it'll just change the throttle response...so err - what's the big deal? If you have the throttle move inwards on the side with the shortest intake path, then you might end up with slightly laggy throttle response but have a more linear relationship between power output and throttle opening...but if you have it the other way around, you will have snappier throttle response (good air speed), but less linear relationship (peakier) between throttle application and power output.
|
|
|
Location:
Lost in the K hole
Registered:
May 2002
|
|
Re: does it matter which way a throttle plate opens??
|
Tue, 05 October 2004 07:47
|
|
i like stories 
|
|
|
Location:
Sydney
Registered:
May 2002
|
|
Re: does it matter which way a throttle plate opens??
|
Tue, 05 October 2004 10:32
|
|
The throttle shafts on my 4AG are vertical and it makes great power albeit with some intake reversion at about 5000 rpm.
Hows that for a story?
Don't panic, we think the reversion is caused by the headers being too small not the orientation of the throttles 
Darren.
|
|
|
Location:
1st street on the right
Registered:
November 2002
|
|
|
Location:
South Australia
Registered:
July 2002
|
|
Re: does it matter which way a throttle plate opens??
|
Tue, 05 October 2004 13:06
|
|
| Quote: |
These days we can gather a lot more info about what happens to the air. It also depends on your plenum design, if it's like the Bm then you want it down. If it's like say a Range Rover, large plenum with trumpets inside then you'd want it flowing up.
|
For what reasons, what are the 'advantages' over the other way around?
|
|
|
Location:
Lost in the K hole
Registered:
May 2002
|
|
Re: does it matter which way a throttle plate opens??
|
Tue, 05 October 2004 15:42
|
|
first up - sorry for my pissy responses during the day... ive had a shocker 
i simply didnt have time to write anything meaningful.
ive yet to have any time to do any serious reading on the matter either.
darren - id be interested to talk to you about the reversion youre experiencing. its a killer, yet i know very little about how to design around it. there appears to be very little info avalable on it also (or perhaps im just reading the wrong books)
hell, i need to have a decent sit down talk with someone about intake velocities and harmonics in general...
|
|
|
Location:
Sydney
Registered:
May 2002
|
|
Re: does it matter which way a throttle plate opens??
|
Tue, 05 October 2004 22:34
|
|
Ed,
The reversion happens just after it starts to come onto the cams, it's almost as though the headers can't handle the sudden increase in flow.
We tried smaller, straighter inlet trumpets which helped reduce it (and also made a heap more power as a little bonus). Now we are trying some things with stepping and collector design in the headers. Then we've got some new CNC'd trumpets (they are simply spank worthy!) with different shapes that may or may not work. Ultimately we might try a horizontal throttle shaft, provided I don't run out of money
When we get the car back on the dyno, hopefully in the next couple of weeks, come out and have a look.
|
|
|
Location:
Gold Coast
Registered:
May 2002
|
|
Re: does it matter which way a throttle plate opens??
|
Tue, 05 October 2004 23:34
|
|
|
Many of the high performance race engines I have seen also have slide throttles or throttle plates pivoting on the vertical axis. Personally, I feel this suggests it doesn't make a great deal of difference which way they open.
|
|
|
Location:
Lost in the K hole
Registered:
May 2002
|
|
Re: does it matter which way a throttle plate opens??
|
Wed, 06 October 2004 00:14
|
|
| Darren wrote on Wed, 06 October 2004 08:34 |
Ed,
The reversion happens just after it starts to come onto the cams, it's almost as though the headers can't handle the sudden increase in flow.
We tried smaller, straighter inlet trumpets which helped reduce it (and also made a heap more power as a little bonus). Now we are trying some things with stepping and collector design in the headers. Then we've got some new CNC'd trumpets (they are simply spank worthy!) with different shapes that may or may not work. Ultimately we might try a horizontal throttle shaft, provided I don't run out of money
When we get the car back on the dyno, hopefully in the next couple of weeks, come out and have a look.
|
darren, id be very interested to stick my head in on the dyno 
ill PM you my number...
|
|
|
Location:
South Australia
Registered:
July 2002
|
|
Re: does it matter which way a throttle plate opens??
|
Wed, 06 October 2004 04:02
|
|
My guess is that any reversion will be related to harmonics in the design of the manifold/ports/valves, but then again I have no idea what kind of set-up you are using 
|
|
|
Location:
Sydney
Registered:
May 2002
|
|
Re: does it matter which way a throttle plate opens??
|
Wed, 06 October 2004 04:49
|
|
| FWDboy wrote on Wed, 06 October 2004 14:02 |
My guess is that any reversion will be related to harmonics in the design of the manifold/ports/valves, but then again I have no idea what kind of set-up you are using
|
100kw 4AG, 320deg TRD cams, shim under buckets, big valve springs, port work, 45mm (i think) throttle bodies, fabricated manifold, yadda yadda yadda... nothing that hasn't been done before. But the headers are small diameter sand bent ones.
I guess only Dyno time will tell. It could well be the vertical throttle shafts!
|
|
|
Location:
South Australia
Registered:
July 2002
|
|
Re: does it matter which way a throttle plate opens??
|
Wed, 06 October 2004 05:03
|
|
|
I'm hoping that later this year I will start work on a real-time flow simulation that will be able to compute these kind of problems numerically in real-time (and thus be able to respond to certain realistic conditions) based off of CAD designs.
|
|
|
Location:
tallahassee FL usOFa
Registered:
May 2002
|
|
Re: does it matter which way a throttle plate opens??
|
Wed, 06 October 2004 15:32
|
|
yes. on which ever side it is easiest to put the idle system & acc. pump jet.
i think its a manufacturing decision rather then performance or engineering.
|
|
|
Location:
Sydney
Registered:
May 2002
|
|
Re: does it matter which way a throttle plate opens??
|
Wed, 06 October 2004 22:16
|
|
| allencr wrote on Thu, 07 October 2004 01:32 |
yes. on which ever side it is easiest to put the idle system & acc. pump jet.
i think its a manufacturing decision rather then performance or engineering.
|
Which idle system and acc. pump jet would that be Allen?
|
|
|
