Larger Throttle Bodies

J1 · Post by J1 » Sun Jul 25, 2004 8:25 am

I've read on the RPW website that it's possible to fit a larger throttle body to the FTO or even dual throttle bodies. Has anyone actually done this before? If so, are there any noticeable gains or results?

The stock is apparently 60mm and they can bore it out to 63mm or replace the stock unit with a larger 65mm unit. Doesn't seem too expensive, but just wondering if it's worth it

TimmyD · Post by **TimmyD** » Sun Jul 25, 2004 1:54 pm

whats a throttle body?

Boris · Post by **Boris** » Sun Jul 25, 2004 5:52 pm

TimmyD wrote:whats a throttle body?

The throttle body is what controls the volume of air entering into the engine and is located at the beginning of the intake manifold at the start of the plenum chamber. From there it is distributed down the four "Runners" to the cylinder head. The size of the throttle body directly affects the volume of air entering the vehicle and as such, can have dramatic effects on throttle response, acceleration, torque and overall horsepower.

Tim, you know that thingo that the intake pipe from your airfilter goes in? The thingo that has that other thingo that's called a butterfly valve... which controlls the volume of air going in... Well that whole thingo is called a throtle body...

k?

DZYRME · Post by **DZYRME** » Sun Jul 25, 2004 8:55 pm

Boris wrote:
Tim, you know that thingo that the intake pipe from your airfilter goes in? The thingo that has that other thingo that's called a butterfly valve... which controlls the volume of air going in... Well that whole thingo is called a throtle body...

k?

Thats got to be one of the best descriptions ever said. Well done!!

FTO338 · Post by **FTO338** » Sun Jul 25, 2004 10:41 pm

Don't forget you also need to replace the butterfly. & I would get RPW to send some very high resolution picture of their TB first. Cause if its the same quality as the extractor, then you be very disappointed.

GWIDO · Post by **GWIDO** » Mon Jul 26, 2004 11:56 am

i got the oversize tb from RPW.
It is the original one machined and with and oversize buttler fly.
All the changes are internal so it is identical,
Much better throttle response.

Post by **smorison** » Mon Jul 26, 2004 11:59 am

GWIDO wrote:i got the oversize tb from RPW.
It is the original one machined and with and oversize buttler fly.
All the changes are internal so it is identical,
Much better throttle response.

really???
i find that hard to believe considering all the testing we have done on the stock one.... what other mods did you make at the same time???

Beme007 · Post by **Beme007** » Mon Jul 26, 2004 2:56 pm

I dont really trust RPW stuff.
since I dont see many good respone from ppl who got their prodcut.

J1 · Post by J1 » Tue Jul 27, 2004 1:26 am

GWIDO wrote:i got the oversize tb from RPW.
It is the original one machined and with and oversize buttler fly.
All the changes are internal so it is identical,
Much better throttle response.

Do you know how much they bored it out? 63mm I'd assume? I don't suppose you have any dyno figures to back up that claim? The bored TBs don't exactly come cheaply. Also, does anyone know of a place in Melbourne that does this kind of stuff? I'm a little skeptical about RPW goods as well...

Blk-Jet · Post by **Blk-Jet** » Wed Jul 28, 2004 5:54 pm

I've done this mod myself. Bored it out to 63.5mm. Much better throttle responce and notisible improvement a tthe top end but only slightly. If you want a price for it, pm me with your details and i'll get back to you. We have the jogs and butterflies ready.

--Frank

GWIDO · Post by **GWIDO** » Mon Aug 02, 2004 2:17 pm

from memory it went out to 65mm (i think)
If i remember right the final size depends on the quality of the original casting, so some are slightly thicker and can be taken out more and othes can only go to about 63mm.
Smorison,
What tests have you performed to discredit this product?
ie have you got a 65mm throttle body fitted to your car?
you say you have done testing on the stock one, how can you test it without making it larger?
DO YOU HAVE DYNO RESULT TO PROVE THAT IT DOESN'T BENEFIT?
beme007. You see many responses from people but how many are from those who actually have the rpw products?
The only bad things i have seen, heard is they do not provide dyno graphs and that there is weld splatter on the extractors, can anyone point out anything else?[/quote]

RichardH · Post by **RichardH** » Mon Aug 02, 2004 3:46 pm

> DO YOU HAVE DYNO RESULT TO PROVE THAT IT DOESN'T BENEFIT?

I'll just put in my earplugs while you shout, and try to answer this one regardless.

I saw some dyno results of testing a bored out FTO GPX throttle body somewhere. I think I have it in a mag at home (UK FTOOC newsletter, possibly). I'll have a dig around later on today.

So before anyone goes mad and starts more shouting, just hang fire and I'll see what I've got in my FTO pile-o-crap.

- Rich

PS. I did dyno my stock FTO back-to-back with another GPX that had bored out RPW throttle body and induction manifold plus RPW long bendy pipe to cone filter in front of radiator. But that's another story....

Me? A tease? Nah............................................

ruchi · Post by **ruchi** » Mon Aug 02, 2004 3:55 pm

ooh, I'm going to get me some popcorn and sit down and watch this thread, it's more entertaining than some of the stuff of TV!

RichardH · Post by **RichardH** » Mon Aug 02, 2004 4:07 pm

Don't get too excited about a potential flame war... I think GWIDO is a West Aussie owner like me, hehe. Us lot gotta stick together way out here in the wild west, lol.

- Rich

MADFTO · Post by **MADFTO** » Mon Aug 02, 2004 4:15 pm

People must remember that an engine is just a complicated air pump (even more complicated with FI =PPP)

An increased TB will allow (emphasis on allow) a higher flow rate but won't do anything substantial on its own if it isn't the most restrictive point in the whole system.

People must remember, every engine is different as stated, component casting isn't precise in mass production environments unless it's specifically required. Doesn't mean they are completely out of spec but there are tolerance levels.

Anyways, a lot of flow mechanics involved in engines, but butterfly valve size won't make that huge amount of difference for most people for the money involved. It'll be most noticed when the car is demanding the most from the intake system (what during higher RPM zone), not many of us would be using that zone for more than a few seconds at a time. I'd be more worried about feeding the filter with a good supply of cold clean air first.

But it's somewhere to look for gains if you're trying to get the most without replacing the whole intake manifold. =)

G_A_V · Post by **G_A_V** » Mon Aug 02, 2004 8:36 pm

i was thinking why bore out the currect intake system, why not just make a new one in carbon fibre, and instead of comming out the top of the engine, going back rand then doing a uturn, why not just come staight out and forward ??.
i guess such a system would be very loud though

MADFTO · Post by **MADFTO** » Mon Aug 02, 2004 11:52 pm

Well, it's not really feasible to go forward unless you want remove the throttle bodies every time you change your oil =)

And it's going to be hard from the side to fit all the pollution gear, you also need to have good length primary runners so you can feed in air that isn't so turbulent, unless of course you don't give a damn about low to mid range torque =)

That's another story =)

J1 · Post by J1 » Tue Aug 03, 2004 1:10 am

RichardH wrote:> DO YOU HAVE DYNO RESULT TO PROVE THAT IT DOESN'T BENEFIT?

I'll just put in my earplugs while you shout, and try to answer this one regardless.

I saw some dyno results of testing a bored out FTO GPX throttle body somewhere. I think I have it in a mag at home (UK FTOOC newsletter, possibly). I'll have a dig around later on today.

So before anyone goes mad and starts more shouting, just hang fire and I'll see what I've got in my FTO pile-o-crap.

- Rich

PS. I did dyno my stock FTO back-to-back with another GPX that had bored out RPW throttle body and induction manifold plus RPW long bendy pipe to cone filter in front of radiator. But that's another story....

Me? A tease? Nah............................................

Do you have the dyno results of that comparison anywhere? I just so happen to have an induction manifold plus RPW long bendy pipes. But I have a HKS pod filter, not a cone filter

Did you ever find that mag?

Post by **smorison** » Tue Aug 03, 2004 9:00 am

to answer Gwido's question...

we did a vacuum test on the TB well over a year ago... if i can find the dyno result amongst that 107 that we have done on my car i'll get it and publish it...

the result (and i can't remember the configuration of the car) was less than 0.1inch of water, (which is bugger all)... however as i said i can't remember what mods were on the car at the time so it's hard to judge...

however to statisfy my own curiousity as much as everyone elses the next time i'm around at Unique and have time i'll do a vacuum test again to see if there could be any gains made...

for those that want to work out pressure use this:
http://www.members.optusnet.com.au/ncri ... ssure.html

0.1 inch of water =
0.003612729209 psi
0.0002490889 bar

Beme007 · Post by **Beme007** » Tue Aug 03, 2004 11:42 am

Man.. why dont RPW release some dyno result to prove it ?
if they use dyno graph to back up their product . There wont be so much flaming on RPW product .
and I dont see why a Performance Part Company dont give a dyno result to back up their product.

FTO AUSTRALIA

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