R33 Rb30 Conversion

[DennisRB30]

It's interesting to note that the RB30 has DOUBLE the power all the way up to 4000 RPM, considerably more from 4000 to 6000 and the power levels are about equal up to 6400. After that it is down on power compared to the RB25 but only by a tiny bit.

[Cubes]

Mine does 100km/h at 3875rpm.

So the calculation is pretty spot on given the R33's have a higher diff ratio.

Thats pretty insane really thinking that he is making at 3500rpm what I am making at 7000rpm and the funny thing is I also have more lag!

wahahahha..

I noticed the inlet valves are quite large.

They basically fill the while side of the chamber.

Would be hard to fit larger ones unless you were to move away from circle valves.

When I get the RB20DET out i'll take photo's of its head and show compare photo's with the RB25 head.

[25t]

had to travel 1000+ks but it was worth it,

280hp at wheels with 14psi boost(did see peak 300hp but dyno sheet says 280)

for those who dont know i have bolted the 25t head onto a rb30 na bottom ,im still running the 25t ecu,turbo,injectors,intercooler,etc

mobs are simply K&N pod full 4inch exhaust and elect boost controller

had problems with my original bleed valve making spikes up to 17psi and causing boost cut had to buy and fit a ebc

fuel mixtures were fine, still running rich at full boost though ,obviously the 370cc injectors are up to the task

the only thing that caused concern was the timing having to run at 27deg advance to preform ,this had the dyno mech rather confused ,a few degrees more and detonation was heard

SYDNEY KID/ Anyone do you have any idea why the hybrid has to run so advanced to make power do i need adjustable cam gears?????

all the same ,im very impressed with the cheeap hp, sure beats forged pistons/aftermarket ecu on cost

cheers

[DennisRB30]

The lower CR allows more timing to be added.

[Cubes]

With good fuel etc.. I had 25degree's pumped in to the RB20DET at one stage when the weather was cold.

Can you scan a copy of the dyno run and print it up?

[RNS11Z]

in 4th gear @ 100km/h my cars at 3500rpm exactly

[DennisRB30]

Originally posted by RNS11Z

in 4th gear @ 100km/h my cars at 3500rpm exactly

Hmm, conflicting information. My chart might be wrong then.

[Cubes]

Depends on the wheels he is running.

Mine does 3875rpm at 100km/h and at 3500rpm its doing 95km/h.

I just worked it out with a 4.11:1 diff ratio and it is 3500rpm at 100km/h.

This is using stock wheel sizes.

Remember we are going off a Dyno printout here and it won't be accurate.

i.e 100km/h on the rollers isn't going to be 100km/h on the road.

[DennisRB30]

Ahh close enough then.

BTW, changing the wheel size won't do anything to change what your speedo says at any given engine RPM.

I would have thought that the dyno would have been more accurate at telling actual road speed than any car speedo because wheel size would not be an issue (but the speedo would read wrong if you changed wheel size, which would throw out any calculations based on dyno speed)

[Cubes]

Wheel size does make a difference what your speedo reads.

If you run a small arsed 13" wheel your spedo is going to be saying that you are doing 130km/h when you are only doing say 90km/h.. .

But yer.. I would have also thought that a dyno would have been more accurate BUT.. when I had mine done it was way off with the speeds.

[DennisRB30]

"If you run a small arsed 13" wheel your spedo is going to be saying that you are doing 130km/h when you are only doing say 90km/h.. "

Yeah, but your tacho will still say 3500rpm (or whatever) when your speedo says 100km/h (in the respective gear). You could throw your wheels taishaft and diff into the ocean and that would not change

[25t]

Joel

the dyno sheet is not a computer print out such as the ones guys post around here ,but is a hand written sheet with the fuel ratios

and h/poer in each gear

ill try and scan it and post

[GiJOr33]

doesn't matter what size wheel you have, as long as the profile tyre is right. You can have a 19" wheel with a 20 profile tyre (if they exist), and that will be the same diameter across from tyre edge to tyre edge as a 15" wheel with a 90 profile... i know these aren't exact, but i'm just using them as an example. If you had a 19" with a 30 profile and a 15" with a 30 profile then the diameter's of each wheel from tyre edge to tyre edge will be different.

[Cubes]

Thats true Gijor33.. BUT.. I had 16" 225 50' VR GTS 16's on my VS commodore. When I went to slap the spare on the arse end it was slightly higher. It wasn't much (1.5-2cm's) but it was enough to cause the car to steer left when accelerating and steer right when decelerating.

Who really matches their new wheels up to the standard sizing. Not many if any

[DennisRB30]

It is a good idea to try and keep the rolling diameter the same, or at least calculate the difference it is going to make to your speedo. Otherwise you might find yourself getting booked for speeding all the time.

[DennisRB30]

Try this http://www.miata.net/garage/tirecalc.html

And this http://www.c5-corvette.com/tirecalc.htm

[-scooter-]

Hey all.....

First of all, Excellent Thread. BLOODY TERIFFIC MATES.

After reading all of this thread i have come to the conclusion that the series 2 commondoor block is the best for the conversion as it has all the oil/water inlets and returns and what not, for the turbo applaction...

Now my QUESTION is, how do you tell the difference between the series 1 & series 2 blocks????????

I live in brisbane, so some of the wreckers up here are a bit dodgey and would prob try and sell me a series 1 block if they did not have a series 2.....

SOOOO it would be good to be able to tell the difference betwwen the 2.

Thanks in advance people ;)

[Skyrine-Dave]

i am chasing 250rwkw+ to get my boat moving.

I'm wondering how much power the stock pistons(NA VL) will cope with before they explode. Would the strength and longevity/power produced be increased by cryo/heat treating the stock NA pistons?

*i have gone back thru the thread to look for my answer too *

[2fardown]

I have read the entire thread and would like to ask a few questions:

1. Will the engine fit straight into the engine bay or will there have to be modifications of engine mounts etc etc?

2. If this conversion is so easy and the end result a powerful engine....why didn't Nissan ever develop and include the RB30DET in one of there cars?

Cheers.

[Steve]

Pistons longevity is probably more related to tune than outright power.

I would think that if you can make that sort of power with an RB25DET on stock (9:1 CR) internals, an RB30 with RB25 head and NA pistons would be just as easy to achieve as the CR is a bit lower, therefore less prone to detonation - which is the real enemy of the pistons, not power.