GTR throttle body upgrade

[mark99]

Ive read of an upgrade for gtr's where you replace the 6 x 45mm throttle bodies, with 6 x 50mm throttle bodies. Can anyone help me with who makes this, or where i can get them from??

[600hp]

Tomei make the Kit. i believe its around 1500AU i could be wrong.

they also make a kit wich replaces the original throttles with a one. at the front of the plenum.

You would want to be making big power and also may consider the Greddy plenum.also i know that CRD are releasing a plenum for the GTR very soon give them a call.

[mark99]

I had a quick look at the tomei site, and cant see it... you wouldnt have a link to any info by any chance? Yeah im hoping to make pretty decent power, but dont want to go the single throttle body route....

[Sydneykid]

I had a quick look at the tomei site, and cant see it... you wouldnt have a link to any info by any chance? Yeah im hoping to make pretty decent power, but dont want to go the single throttle body route....

We are up tp 420+rwkw (625bhp) with the standard throttle bodies, no noticeable restriction. On the flow bench or the chassis dyno. That's for circuit racing, plus there are plenty of cars running 9's with the standard throttle bodies.

[mark99]

We are up tp 420+rwkw (625bhp) with the standard throttle bodies, no noticeable restriction.  On the flow bench or the chassis dyno.  That's for circuit racing, plus there are plenty of cars running 9's with the standard throttle bodies.

Im hoping to make more than 420rwkw, and would like to try both standard and the larger size throttle body setup if its readily available. With the combination im putting together im hoping that i may see some gains in top end power.

[Sydneykid]

Im hoping to make more than 420rwkw, and would like to try both standard and the larger size throttle body setup if its readily available. With the combination im putting together im hoping that i may see some gains in top end power.

Then you should go single throttle body, you won't notice any loss of throttle response at that power level. The turbo/tubos will be so big that they will have more lag than using a single throttle body will introduce:cheers:

[mark99]

Then you should go single throttle body, you won't notice any loss of throttle response at that power level. The turbo/tubos will be so big that they will have more lag than using a single throttle body will introduce:cheers:

I would prefer to stay with the six throttle body setup though... Then i can try both standard and larger and see what, if any, gain or loss i experience

[Sydneykid]

I would prefer to stay with the six throttle body setup though... Then i can try both standard and larger and see what, if any, gain or loss i experience

It's a large expense for testing, expecially testing that has already been done by many people. RB powered GTR's have been arround for 16 years, circuit racing drag racing and road cars, there is very little that hasn't been well and truly tested in that time. My suggestion, as always, is to spend the money on something that actually makes the car faster.

[mark99]

It's a large expense for testing, expecially testing that has already been done by many people.  RB powered GTR's have been arround for 16 years, circuit racing drag racing and road cars, there is very little that hasn't been well and truly tested in that time.  My suggestion, as always, is to spend the money on something that actually makes the car faster.

So what you are telling me is that increasing the size to six 50mm throttle bodies will make no difference to how fast my car goes at all??? If so, thats cool you've saved me having to try both setups. But how do you know this, have you tested the larger setups, or are you saying that if you are after large power and are going to change from standard then going to single throttle body is smarter because it leaves you scope for yet more power again than the six 50mm throttle bodies? Also if 600hp is correct arond $1500 is a lot cheapaer than say a Jun plenum and sigle throttle body, isnt it? But only if that $1500 is gonig to make my car go faster... All help and opinions are appreciated

[Sydneykid]

So what you are telling me is that increasing the size to six 50mm throttle bodies will make no difference to how fast my car goes at all??? If so, thats cool you've saved me having to try both setups. But how do you know this, have you tested the larger setups, or are you saying that if you are after large power and are going to change from standard then going to single throttle body is smarter because it leaves you scope for yet more power again than the six 50mm throttle bodies? Also if 600hp is correct arond $1500 is a lot cheapaer than say a Jun plenum and sigle throttle body, isnt it? But only if that $1500 is gonig to make my car go faster... All help and opinions are appreciated  

Hi Mark, there are whole pile of issues here and they are heavily interrelated. We are only interested in circuit racing. So drag power levels are not something we have spent a lot of time testing components for. Certainly not to the same thorough levels we do for maximising our circuit speed and reliability. Everything is pretty mucgh engine dyno, chassis dyno and flow bench tested before it is signed off to go racing.

Once you get over ~650 bhp the standard plenum has distribution issues. So it is best to change it, whether going single throttle butterfly or multiples.

The best plenum I have seen in action with the multiple throttle butterfly (standard size) is the Nismo plenum. That combo seems to work very well and ~750 bhp is OK. Maybe more, but I haven't seen it. From what I have seen, the faster circuit cars at Tsukuba use the Nismo plenum.

Over ~750 bhp, upgrading the throttle bodies is not worth it as the turbo/turbos required to make that sort of power are simply not responsive. GTR's making that sort of power are pretty useless for anything other than drag racing and so throttle response is irrelevant anyway.

Once you get to that point, there are number of plenums with single throttle bodies. I prefer the Jun plenum, but the Veilside achieves good results as well. When you get to that stage, plenum cost is pretty much irrlelevant, as you will have spent over $200K on the rest of the car to support and use that sort of power output.

[DaGr81]

mark wat have u got on ur car in terms of engine mods at the moment?

[600hp]

Ring HiOctane for prices on the throttle kit, i know they use to produce the kit.

[mark99]

mark wat have u got on ur car in terms of engine mods at the moment?

Im right in the middle of upgrading at the moment, 3lt bottom end, big cams, ported head, gt-rs turbos, big exhaust, fuel system, etc etc. Im up to looking at different options on the induction side, which led me to looking into the bigger throttle body upgrade.

[mark99]

Hi Mark, there are whole pile of issues here and they are heavily interrelated.  We are only interested in circuit racing.  So drag power levels are not something we have spent a lot of time testing components for.  Certainly not to the same thorough levels we do for maximising our circuit speed and reliability.  Everything is pretty mucgh engine dyno, chassis dyno and flow bench tested before it is signed off to go racing.

Once you get over ~650 bhp the standard plenum has distribution issues.  So it is best to change it, whether going single throttle butterfly or multiples.

The best plenum I have seen in action with the multiple throttle butterfly (standard size) is the Nismo plenum.  That combo seems to work very well and ~750 bhp is OK.  Maybe more, but I haven't seen it.  From what I have seen, the faster circuit cars at Tsukuba use the Nismo plenum.

Over ~750 bhp, upgrading the throttle bodies is not worth it as the turbo/turbos required to make that sort of power are simply not responsive.  GTR's making that sort of power are pretty useless for anything other than drag racing and so throttle response is irrelevant anyway.

Once you get to that point, there are number of plenums with single throttle bodies.  I prefer the Jun plenum, but the Veilside achieves good results as well.  When you get to that stage, plenum cost is pretty much irrlelevant, as you will have spent over $200K on the rest of the car to support and use that sort of power output.

SK thanks, that makes good sense. The key word here is response. The reason i wanted to stay multiple throttle bodies is i was hoping with the combo im running that "response" would still be in my vocabulary whilst making 400+rwkw... but sounds like i may be dreaming?? My thoughts were, if im increasing, capacity, cam lift, cam duration, cyl head breathing capacity, turbo size, exhaust size, then i should increase the throttle body size.....

[600hp]

Look at two 02L they make over 400AWKW and have tops response.

we're not there yet.