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some very differnt powers being made with similar turbos. my rb25 with a gt30 .82 and external gate made 420rwhp @ 27psi

ive added a pic of the dyno sheet, the red line is my first engine with aria pistons and higher compression, the blue line is the same head, less compression and wiseco pistons... I had hi flowed injectors, pump, micro tech etc etc...

some of you guys have made good power on such little boost... have any of you gone down the track??

with 300rwhp i ran 13flat @ 114mph

Track I am refering to is Sandown and Phillip Island were i found i had to modify my driving a fair bit so that when i powered out of the corners I could keep the engine in the power curve of the rev range. Sometimes it was a comprimise between using 2nd gear and wheel spinning out of the corner and loosing time or staying in 3rd and having the car bog down for a while till the needle went near 4000rpm.

some very differnt powers being made with similar turbos. my rb25 with a gt30 .82 and external gate made 420rwhp @ 27psi

ive added a pic of the dyno sheet, the red line is my first engine with aria pistons and higher compression, the blue line is the same head, less compression and wiseco pistons...  I had hi flowed injectors, pump, micro tech etc etc...  

some of you guys have made good power on such little boost... have any of you gone down the track??

with 300rwhp i ran 13flat @ 114mph

That is one hell of an interesting dyno graph RNS11Z. It is not often you get the chance to compare the same engine with different compression ratios. Can you notice the 50rwhp less at ~4,600 rpm? Or does it go through the 4,000 rpm to 5,2500 rpm band so fast you don't feel it? I notice that the current set up has ~1.5 psi more boost at 5,150 rpm, is that deliberate? Or did you have to run less boost with the higher compression?

Lots of things to think about on that dyno graph, for a data not like me anyway.:D

I was having problems with the external gate which is why it wouldnt hit target boost straight away on the first engine. When building the 2nd engine we fixed the gate, as you can see it spiked 1-2psi then settled.

The 2nd engine was much more smoother too drive and felt better on the st. The first engine was real snappy.

Peak power on the first engine was 421.??

i think it would be a tad too big, but it all depends on whay you dont mind living with for the extra power. abo bob has got my power graph, when he posts it up for me you guys can have a look how a gt30 with .63 exhaust makes power on an rb25 with stock compression.

wonder how the GT30 with the .63 would go on a rb20 ;) seeing as the rb20 has stuff all puff

i just might have to try it :)

give me about 2 weeks and my rb20 will be in my s14......

its currently got a gt30r with a .63 ar bolted to a hks manifold with the gate set at 14psi/1bar.

i also threw in tomei procams (260/8.8mm lift intake/exhaust) to help it along and some greddy gears.

currently the fuel rail is loaded with some 550's and gonna burn a custom chip to change redline as well as control the larger squirters.

will be using a emanage to tune with a tech edge wideband.......

should go quitenicely......

oh and some one on here said they used a gt30 with a .86 ar on an rb20 and they got 14psi at around 4k.

I wouldnt question the exhaust.

I'd be looking at the ECU/tuner.

One assumes its aftermarket of course... and there is a very big hole in the power band that should not be there at all.

With the smaller housing it should ramp onto boost easiler also. Which i'd put down too the tuneings fault again

That car for the turbo has a smaller powerband than mine with the bigger housing which in thoery should be a bit laggier

Carl... i'll take you for a burn in mine next week if you want and show you how mine goes with a decent tune :)

Hmm, I found a few things that made mine come onto boost alot harder, and hold better to redline - one of them was exhaust being very restrictive. It wasnt a problem until I got the larger turbo on - just choked it as I turned up the boost. Easy way to tell, just drop the exhaust for a quick run around the block :) or on the dyno if your not feeling adventurous.

Second was a flange leak from the manifold to the ext wastegate - only a small one, not audible by ear, needed a stethescope type device - but made a big difference, boost earlier and far more responsive.

Last one was BOV leaking at higher rpm.

Some ideas anyway, hope they help

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