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R33 Rb30 Conversion

JNR24

By JNR24,
in Engines & Forced Induction

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Cubes Grand Master

Cubes

Posted
Posted
i got my heap of junk dynoed for a bit today, just a quick check to make sure it was OK. fixed the AFR's back to 12:1 and didn't play with timing much at all. total of 1.5 hours on the dyno, 225rwkw at 9psi. graph and stuff can be seen here --> http://www.skylinesaustralia.com/forums/in...howtopic=104332

Looks good stocky.. Any plans to get that s/c providing a little more boost in the low end?

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Duncan
Duncan

Just thought I would bump this 20 year old thread because the Skid Factory have just posted up a video summarising a lot of the content, format might be more familiar for newer members

JNR24
JNR24

fyi guys, Well yesturday i picked up a RB30 for my conversion into my R33. I will be using my RB25DET head on the RB30 block. So i started stripping the motor down, pulled the crank, pistons, girdle

Cubes
Cubes

Here is all I have at the moment: http://www.geocities.com/r32_jjc/ Unless you are on broad band make sure you right click then save as. The file is around 120kb. If there is anything I have got w

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Sydneykid Grand Master

Sydneykid

Posted
Posted
Does anyone know the formula for working out what the compression ratio will be with a standard 30e block & r32 RB25DE head with a 1.0mm metal head gasket??

Simple high school maths (Pi x R2 X H), 0.2 mm reduction in head gasket thickness = 0.1 to 1 increase in compression ratio. So if you had no head gasket at all, you would end up at 8.7 to 1 using RB30E pistons with an RB25 cylinder head.

An alternative (if you have a decent machine shop close by) is to mill the cylinder head 0.3 mm and reduce the combustion chamber volume by 2 cc's. Then install new (unmilled) valve seats which will reduce the combustion chamber volume by 0.8 cc's. Head gaskets of 0.8 mm are available, but to use one you will need to o'ring the block. Do those 3 things and you will end up at 8.65 to 1 which is the best you are going to get while still retaining the standard squish, which is important.

:( cheers :(

StockyMcStock Proficient

StockyMcStock

Posted
Posted
Looks good stocky.. Any plans to get that s/c providing a little more boost in the low end?

nup - it's perfect just as it is. the boost isn't important, it's the airflow that it's providing. it REALLY doesn't need any more bottom-end torque that's for sure. full boost (on the street) is a little later than i was expecting, simply because it goes through the gears so quickly. there's just no time. it mashes first gear and you can destroy 2nd if you really want to . yet to drive it on a cold night :O

it needs to have the cam timing checked to see why the power is dropping off past 5200. hopefully it's just the timing and not something else. pretty f**king happy with it at the moment that's for sure. name me any other RB30 engine with that response, power delivery and peak power on such little boost. i can't think of any.

Cubes Grand Master

Cubes

Posted
Posted
nup - it's perfect just as it is. the boost isn't important, it's the airflow that it's providing. it REALLY doesn't need any more bottom-end torque that's for sure. full boost (on the street) is a little later than i was expecting, simply because it goes through the gears so quickly. there's just no time. it mashes first gear and you can destroy 2nd if you really want to . yet to drive it on a cold night :O

it needs to have the cam timing checked to see why the power is dropping off past 5200. hopefully it's just the timing and not something else. pretty f**king happy with it at the moment that's for sure. name me any other RB30 engine with that response, power delivery and peak power on such little boost. i can't think of any.

Well thats just it, I haven't seen one... But I am greedy.. :(

You are pretty damn close to the same power I had with the rb20det turbo at 2400rpm but with a lot more top end.

I'm certian the issue is with cam timing as you have just disabled the vct and not adjusted the cam timing to suit yes?

I'm curious as to how its all setup.. I'm sure youve mentioned it before.

Where is the turbo's wastegate getting its boost reading from?

StockyMcStock Proficient

StockyMcStock

Posted
Posted

yeah VCT is disabled - but the cam timing is probably out due to the fact that it's a completely non-standard cam belt setup. i basically aligned the notches as best i could by eye, which wasn't very good at all.

DSC00174-1.jpg

as you can see the tensioners aren't in the "normal" place for an RB30DET, because i started with a series 1 block. i like my setup better though, the belts have less length between tension points so there's (theoretically) less flap in them.

turbo's wastegate is reading boost from before the intercooler, but this doesn't really matter. not much would change if i referenced it to the plenum, or after the intercooler. it might run 1-2psi more (pressure rise equal to pressure differential across the cooler) but that's it. the real magic is happening at the 2nd wastegate which is the blower bypass.

i really wish i had a dyno vid to show you guys, not because it looked cool but because of the noise it made. just insane.

Cubes Grand Master

Cubes

Posted
Posted

As you have the turbo's wastegate boost feed after the supercharger wouldn't this essentially cause the turbo to lag as the supercharger will be making boost; IF the supercharger makes enough boost to hold the turbo's wastegate open then the turbo man never really get up on boost?

Is that right?

Have you tried taking the turbo wastegate boost feed from the compressor cover or at least the pipe that runs from the turbo to the supercharger?

StockyMcStock Proficient

StockyMcStock

Posted
Posted

totally true, except the supercharger doesn't make enough boost (straight away) to open the gate. it only makes 5psi on its own, with no positive inlet pressure.

if i took the gate's pressure feed from the turbo-blower connecting pipe, it would likely cause plenum pressure to go up to around 16psi, which i don't want. this is because the blower multiplies the pressure, not adds. so the pressure differential stays the same at, say, 1.4x, so you might only get 5psi out of the blower with no turbo hooked up. connect the turbo and pressurise the inlet, and the final figures might be something like 7psi from the blower and 2psi in the blower-turbo connecting pipe.

if i had to guess (haven't measured it yet), i would say that there is only 2-3psi of pressure in the connecting pipe at full boost. so there is certainly a *bit* left in the old GT40 :O

gtst25 Proficient

gtst25

Posted
Posted
bah come on, yours would be heaps quicker from the info i've seen posted?

It sounds a lot more torquier than most with that supercharger - especially when compared to a mere rb25 like I have.

Can't wait to see how it goes with big injectors + big boost - you'll have some major traction issues!

Cheer

r33_racer Grand Master

r33_racer

Posted
Posted

i think he has some major traction issues now...if he tried i reckon it could nail first three easy. That charger really seems to kick it in the ass down low to get it all started. It looks and sounds wild as from that video.

StockyMcStock Proficient

StockyMcStock

Posted
Posted

yeah it starts spinning 1st gear at about 3500rpm if you keep your foot down, then 2nd it will turn them again when you hit full boost :) shift too quickly like i did in the video and it's all over as far as the tyres are concerned. i'd love to do this to an RB25 to show you guys how easy it is to make huge power out of a twincharge. it would really transform a 2.5 litre engine that's for sure. even better would be a GTR that could cope with the power. the 3 litre bottom end helps a bit, but when you have boost delivery like i have it's not really necessary.

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