R33 Rb30 Conversion

[FORZA-MOTORSPORT]

Guys im getting a custom front facing plenum, for my rb25/30, this will help solve not only the bonnet clearance issues but also the intercooler piping / fan grind . Wondering what size throttle body to go, at the moment tossing up between xf and Q45 90mm, would the Q45 be too big and laggy for a 3L??

[Cubes]

Still an rb20det box as mr_rbman....

Priorities + at the time I couldn't find one for a reasonable price, they were all $1.7-2k, hell even tracking down an rb20det box most wanted up around $800

I had to have the car back on the road quickly; heheh there's always next time, and I'm sure there will be.

[Cubes]

Guys im getting a cutom front facing plenum, for my rb25/30, this will help solve not only the bonnet clearance issues but also the intercooler piping / fan grind . Wondering what size throttle body to go, at the moment tossing up between xf and Q45 90mm, would the Q45 be too big and laggy for a 3L??

Whats your IC piping?

The XF T/B is 65mm so 2.5", I can't see any real gains by having a t/b thats dia is larger than that of your ic piping.

The Q45 t/b is 90mm I believe.. So pretty damn big, wasted if your running 2.5" piping.. But I may be wrong, I'm only speculating and I've wrong many times before.

[ISL33P]

Q45 is acutally 83mm

i have done testing on XF and 80mm tb's and have noticed hardly any difference between the two. obviously power gains were had with the 80mm, not huge but noticeable but its up to you

recommend a 3" intake side and 2.5" turbo side for the cooler piping

[FORZA-MOTORSPORT]

Whats your IC piping?

The XF T/B is 65mm so 2.5", I can't see any real gains by having a t/b thats dia is larger than that of your ic piping.

The Q45 t/b is 90mm I believe.. So pretty damn big, wasted if your running 2.5" piping.. But I may be wrong, I'm only speculating and I've wrong many times before.

Cooler piping is 2.5" and im sure the Xf tb is bigger then 65mm thats the stock rb size isnt it? Bigger tb will still let in more air up top but i guess will give more lag down low...

I got my Z32 now Sard 800cc twin spray injectors on the way too!

[Cubes]

ISL33P,

Are there any negatives noticed with the larger t/b on the rb?

[Cubes]

Cooler piping is 2.5" and im sure the Xf tb is bigger then 65mm thats the stock rb size isnt it? Bigger tb will still let in more air up top but i guess will give more lag down low...

I got my Z32 now Sard 800cc twin spray injectors on the way too!

I remember they could be picked up in either 65 or 68mm. The 68mm's are super rare.

[Craved]

my IC piping is 2.5" all the way and it uses a reducer from the std TB to that size... i dont see how a larger TB on a turbo will help as the pipe is all one diameter and compressed... having a bigger opening for 100mm before the plenum i dont see how that would help in performance

[Cubes]

my IC piping is 2.5" all the way and it uses a reducer from the std TB to that size... i dont see how a larger TB on a turbo will help as the pipe is all one diameter and compressed... having a bigger opening for 100mm before the plenum i dont see how that would help in performance

My only guess would be due to reduce turbulence caused by the butterfly valve. The valve in its self provides a restriction so a slightly larger dia than the pipe used would be required to match airflow.

[Craved]

My only guess would be due to reduce turbulence caused by the butterfly valve. The valve in its self provides a restriction so a slightly larger dia than the pipe used would be required to match airflow.

sounds fair

wonder if knife edging the butterfly plate would help

big thing would the the bar that attaches the plate to the throttle mechanism...

bit hard to smooth the airflow past that ..

just dont wanna hassle around with the new wiring etc, as lots of people have been having trouble wiring up the Q45 to the std wiring

[r33_racer]

not really Craved. Its actually quite simple. We had it almost figured out by ourselves and then Slide came along with his diagram and that made it easy to finish off. We have a q45 tb on our greddy plenum on the 25/30. This is in a s2 r33 also.

Now the diagram is in here also, incase anyone is worried about trying to hook up the q45 throttle body:)

Kudos to Slide!

Edited August 1, 2006 by r33_racer

[Adriano]

Thanks for that, although everyone advertises the Q45 as 90mm, the butterfly is only 80mm(the same size as standard gtr i/c piping

[r33_racer]

I believe the 90mm advertises the OD of the throttle body intake, not the ID. Same with the AFM i think.

[shanef]

r33 racer, what size piping do you have on both sides?

[r33_racer]

The old piping which has just come off...was 2.5" from turbo outlet to the Inlet of intercooler then 2.5" with transition to 3" to the throttlebody, which has a silicon reducer on it to suit the 90 tb.

The new piping I will be fabricating this week sometime to suit the new ARE intercooler will be 2.5" from turbo outlet with transition to the 3" for inlet on intercooler and then 3" out and all the way upto the tb.

Edited August 1, 2006 by r33_racer

[mr_rbman]

You'll quickly find that you'll soon be maxing out those injectors. So i'd look at some larger ones, maybe 720cc's or even 800cc's (their the same price so y not go bigger). Also depends on what cams ur going for will determine if you need to upgrade ur springs. Also the rb30 wont be revving too hard (nothing near 8000rpm i hope) so you shouldnt need to do the valvetrain if everythings in ok order.

So i'd suggest Sard 800cc injectors, BOSCH 044 fuel pump, some JUN or TOMEI 264duration 9.25mm lift IN 272 duration 9.25mm lift EX cams & some cam gears (not hks ones, as they have been known to slip)

Then a retune and you should be seeing some decent power

Probably didn't make my first post very clear, i'm currnetly making 228rwkw's which feels quite nice on the street but as always more is better, I'm thinking with a FPR i should be able to make a safe/reliable 270 rwkw's (with my GTR injectors) which will suit me just fine, i figure that cams is whats holding me back engine/power wise!

But as R33racer said i definitely don't have endless pockets so i'm going to take a bit of a risk and get some GTR cams and get a weld and regrind done to them along with some cam gears and at the same time i'll get my valvesprings installed along with my fuel pump and FPR.

I figure these mods will get me up somewhere round my goal then i'll start saving for an rb25 gearbox and new clutch, unlike Cubes my car isn't a daily driver so i can afford to have it off the road for a while and at the moment my gearbox hasn't shown any signs of going bang and i do baby my shifts 95% of the time!

[FORZA-MOTORSPORT]

Im thinking of leaving stock tb with custom plenum now as it is same size as 2.5inch piping anyway! Is there any benefits from 3inch intercooler piping upgrade on the 3L with a bigger Q45 tb? Or is it just more top endpower?

[Cubes]

The std throttle body tapers down to the smaller butterfly valve.

So... The XF or even larger Q45 will always be better.

Measure the butterfly valve.

[Cubes]

I figure these mods will get me up somewhere round my goal then i'll start saving for an rb25 gearbox and new clutch, unlike Cubes my car isn't a daily driver so i can afford to have it off the road for a while and at the moment my gearbox hasn't shown any signs of going bang and i do baby my shifts 95% of the time!

Mine didn't show any signs of stripping teeth either..

Mine had an input shaft bearing noise from day one, it had only slightly got louder + it wasn't a bearing that failed anyway.

Its not the gear changes that break the box its the pure torque, simply loading it up in third gear as you wind it out of a corner. Mine broke at partial throttle, wasn't even at wot.

I posted up pics of the teeth that fell out of the drain plug on my old box, a few ppls in the know stated it failed due to fatigue.

Essentially the teeth reach their loading point then start bending slightly every time you give it stick, this slight bending slowly weakens them, similiar to bending a coat hanger to break it. Then one day... Bang. No more box clunk clunk.

There is no sign that the box will go when it fails in such a way.

More power and you will need a gearbox.. I say sell yours while its still good so you get some kind of return on it to make up for the more expensive rb25 box, at least it won't hit your pocket as hard that way.

[Sydneykid]

A few years ago we tested the standard RB25 inlet manifold, throttle body and 75 mm intercooler pipework on the flow bench and it showed almost zero pressure drop at an airflow rate equivalent to 500 bhp (300 rwkw). We didn’t test any higher as that was the limit of the standard RB30 internals..

On the R34GTT did the usually boost pressure test, comparing the boost pressure at the compressor outlet with the boost pressure at the plenum and at 315 rwkw there was less than 2 psi pressure difference. That’s with a standard R32GTR intercooler.

So until you get well over 300 rwkw I would be worried about the intercooler pipework, the throttle body or the inlet plenum being any sort of restriction

cheers