R33 Rb30 Conversion

[Cubes]

The RB25DET has 8.3:1 from the factory.

Not it doesn't.

[Guilt-Toy]

What would my compression ratio be for stock rb30e bottom end and pistons with 25 head only shaved to give a good seal ??

[fatz]

the block im using looks like it need to be bored 40th

now looking in rocket the rb30det pistons seem to only come in 86.5

i asume ive missed somethinga nd can get the 87mm pistons if nessasary

or do i just go a rb26dett 87mm piston?

cheers

pete

[SirRacer]

with those pistons and a 0 deck height 8.5, otherwise with 1mm deck height around 8.3 from memory

changing the pistons to rb26 will end up with a nasty compression ratio, acl make replacements that go 1mm oversize so use those. part number 6mkry2799 .100 . they are standard rb30e pistons with chromoly rings.

[Cubes]

Do not use the rb26 piston. Its pin height is not suitable.

[fatz]

just emailing rocket to confirm that they sell the 40th 30 litre pistons

pete

[fatz]

dam im stupid

they do have a 87mm piston fo rthe rb30det

[[200]]

were u after a set of foriges?

i can get cp's with rings for 1300 in the .040' oversize (87mm)

[fatz]

im an arias man through and through

there my babies

[SirRacer]

on a more informative note without trying to sell parts (interesting that cp say they dont make pistons for rb30/25, i emailed them) have we reached a consensus on what oil pump is best used with what restrictors.

im not going to go ahead with my fully done 350kws + rb30, rather aim for near the 300 mark and want to know what restrictors would work well with an rb25de pump.

the rb25de and rb20det in r32 series share quite a bit common so it may even be the same as the 20det pump

[conan7772]

I'm still overwhelmed with the torque of this engine.

Always owned 4 cylinders cars in the past, totally different driving.

With the RB30 at say 90-100 km/h, further accelleration is best to leave it in 5th gear !

Gearing down to 4th or even 3rd at this speed seemed to be of no benefit at all.

I guess this is where warmer cams come in.

The response in fifth is so punchy it'll go from 100 - 130 in 3 secs.

With the RPM at 3000 at 100 km/h and full boost reached at 3200, it's clear to see why.

Anyway, still have bigger injectors to come and to max out this turbo next tune.

Maybe later some NOS, after watching the Dyno shootouts at Penrith last Sunday.

Saw a NA XR6 jump 100 bhp with NOS(max 316) and almost skip off the drums.

Imagine the same with the RB30DET...

Edited May 9, 2006 by conan7772

[r33_racer]

cp do make pistons for rb30/25, they are called rb30/26

[mr_rbman]

well i now have my xr6 turbo on but now have valave float which i guess was to be expected using the NA rb25de valave springs (upgrade to GTR if using this head before you put the motor in your car!)

But considering i can only rev the car to about 5900rpm i think its still making good power and best of all its making 15psi by 3900RPM which i think is awesome considering the 1.06 exhaust housing! It seems to start boosting as early as 2500RPM!

I've attached some of my dyno sheets and engine bay pics, as you can see by the engine bay its pretty stock looking apart from that blue 90 degree silicone hose which is already starting to frustrate me! hehe!

The injectors are up around the 85% duty cycle, does anyone know how much more i can safely push them maybe with a fuel regulator?

Everything seems to be going pretty well apart from a small oil leak coming from the turbo side which i haven't isolated yet and the torque of the motor has made my short shifter move i think which is making it hard to get into thrid gear so i'm going to have to fix that.

Now i guess its just a waiting game to see how long the RB20 gearbox lasts, its in pretty good nick but the torque is crazy.

The only problem i'm finding is that first and second revs out so quickly its virtually unusable especially with my rev limit set at 5800RPM, I've just purchased myself a Nismo 1.5way LSD so before i put that in i think i'll put some 3:9 diff gears in!

[FORZA-MOTORSPORT]

nice mate , think i gonna have that valve float prob too! How hard is it to change the valve springs and can they be done with the head still on???

[Sydneykid]

well i now have my xr6 turbo on but now have valave float which i guess was to be expected using the NA rb25de valave springs (upgrade to GTR if using this head before you put the motor in your car!)

But considering i can only rev the car to about 5900rpm i think its still making good power and best of all its making 15psi by 3900RPM which i think is awesome considering the 1.06 exhaust housing! It seems to start boosting as early as 2500RPM!

I've attached some of my dyno sheets and engine bay pics, as you can see by the engine bay its pretty stock looking apart from that blue 90 degree silicone hose which is already starting to frustrate me! hehe!

The injectors are up around the 85% duty cycle, does anyone know how much more i can safely push them maybe with a fuel regulator?

Everything seems to be going pretty well apart from a small oil leak coming from the turbo side which i haven't isolated yet and the torque of the motor has made my short shifter move i think which is making it hard to get into thrid gear so i'm going to have to fix that.

Now i guess its just a waiting game to see how long the RB20 gearbox lasts, its in pretty good nick but the torque is crazy.

The only problem i'm finding is that first and second revs out so quickly its virtually unusable especially with my rev limit set at 5800RPM, I've just purchased myself a Nismo 1.5way LSD so before i put that in i think i'll put some 3:9 diff gears in!

Personally I wouldn’t get too carried away with changing the diff ratio, the standard R32GTST diff ratio of 4.363 to 1 will give you ~275 kph at 7,500 rpm in 5th using 245/40/17 tyres. So it is hardly short of top speed. Cruising at 110 kph in 5th gear results in 2,950 rpm, which keeps it off boost for all but the heaviest of throttle applications. You can roll on and off the throttle to hold a constant speed without getting a mad rush of boost/power, which helps the fuel economy too.

I like the current first and second gear ratios, with the 4.363 diff, as I can slip off the line with no boost, shift at 3,000 rpm and still easily beat most cars. If you tall up the diff ratio you will find you have to use boost to achieve meaningful acceleration.

Don’t let the VL RB30 Commondoor 3.7 diff ratio fool you, they came with 14” wheels as standard, 15“ was an upgrade.

cheers

[Sydneykid]

nice mate , think i gonna have that valve float prob too! How hard is it to change the valve springs and can they be done with the head still on???

Changing vlave springs without removing the head is easy. Compressed air via the spark plug hole is enough to hold the valves closed while you remove the collars and swap the springs. I use the leak down tester, as it has all the necessary plumbing fittings to get a good seal.

cheers

[Cubes]

Hey Ash,

If you wish email the larger pics of the dyno sheets so we can read them?

I'm curious how much louder its made the car? So overall... honestly. would you recommend the xr6 turbo on an rb30det?

[VHR32]

Don’t let the VL RB30 Commondoor 3.7 diff ratio fool you, they came with 14” wheels as standard, 15“ was an upgrade.

cheers

VL's have a 3.45 diff (V8's 3.08)

Wheel size doesn't have anything to do with diff ratio does it???

[Bl4cK32]

I seem to be the only one without any float....yet

i still will be using the 3.9 or 3.7 diff ratio as i like to move off the line without boost, but changing it up at 3k is lightning fast. I dont do drags, or lots of trackwork, so the benefits the taller diff bring will be ok for me. It will be tuned soon with it, so i'll post results.

[Cubes]

I think you are right on the edge Bl4ck32,

When I was datalogging I noticed a couple of little odd spots that resembled the same I saw with mine when valve float was only just beginning.

To others.. This is a nice little gear ratio/speed calculator.

http://locost7.info/gearcalc.php