Silvia Club of NSW

A couple of quick notes, you can't say for sure if the 2530 would hold 20psi to redline on Step 2s as that means more airflow demand so it bceomes hard to compare yours with TMBs setup.

My speculation is that the GTRS would get close to 300rwkw if it had a better turbine. IIRC (lol) on Freshalloy its about 30-40rwhp difference between the 0.64 and 0.82 on a GT2871R. Thats a bit! But its friggin laggy...

Well I'll leave it at that, we will part at our disagreement as people seem to get bored listening to our dribble.

at the end of the day your right people are bored and we are dribbling, but its still good to delve deep and see what you can come up with

maybe one day some back to back testing will see us somewhere definate hehe

I for one like a difference of opinion as long as it doesn't get personal. Sometime a healthy debate brings up a point that may not have otherwise surfaced under the "this is the way everyone else does it" info which although informative doesn't necessarilly get tothe root of WHY it is done that way.

_________________
I didn’t break it, I just modified the operational status...
There are 10 types of people in this world, those that understand binary, and those that don't.

You guys talk too much!

I'll add a few things


I'm very surprised at this. The 18g front wheel is known to flow a hell of a lot of air. Perhaps there are other issues in your setup (perhaps that contributes to your surging issue). Also the wastegate actuator on the trust turbos are shit. I got a much stabler boost curve on my td05-18g by chucking the trust wastegate actuator in the bin and custom fitting an aftermarket one


There are more differences between your 180 and my 200 than just cams. The 200 is also running higher comp and cam gears (properly dialed in) as well as being an S15 motor. What you will find is that at the top end, my engine may have say 80% VE whereas yours might only have 75% VE.
'Boost' is just the inability of an engine to suck in all the air supplied to it. If my engine has a higher ability to suck in air, then it makes sense that the turbo won't be able to 'oversupply' air to the same extant as on your engine



-The 200 is running a normal old $200 stainless manifold. They are excellent value but not the best design in the world. I do think a properly designed manifold COULD gain 10rwkw on my setup due to nice collector design rather than enything else
-I agree there could be 10rwkw to be gained from an external gate. We have agreed that the limit on my car is the turbine/exhaust housing and not the comp wheel, so anything that frees up the flow in the exhaust housing is going to definately see decent gains. Porting the exhaust housing could also give a few rwkw.
-I think there is more than 30rwkw to be gained from the upsizing of the turbine. My example-
The drift car that omg is playing with has a 3071 on it. This turbo is basically a 56 trim 71mm compt wheel with a gt30 rear end. It makes a conservative 300rwkw at 20psi
Compare this to the most real power people seem to be making from the some comp wheel but with the NS111 turbine (gt2871rs-56t) - I haven't seen anyone make more that 260rwkw.
Thats 40rwkw from a turbine upgrade straight away.
-Head porting on an engine with 350+rwkw is going to make a much bigger difference than on an engine like mine where the port size isn't really a restriction. I guess the thing is that an engine with 250rwkw is going to have a different set of bottlenecks in the system that an engine with 350rwkw

_________________
Disclaimer: I actually DO know everything

Sil80 - SR20DET 231rwkw
Silvia Race Nugget - SR20DET 225rwkw
Stagea - DeathWagon - RB25DET 185rwkw.

My Lame Gallery: http://www.toomuchboost.com/gallery/main.php

Actually would be interesting to get my car on the dyno to put some of this theory into practice and find out what if any difference the porting, exhaust manifold and external wastegate would actually make with the GTRS equivalant turbo.

_________________
I didn’t break it, I just modified the operational status...
There are 10 types of people in this world, those that understand binary, and those that don't.

Nice to see you agree with some of my points TMB. And nah I'm not sure why my 18g won't hold the boost up top. I preloaded the crap out of the actuator using the adjustment and yeah Im thinking the turbo is out of puff. The GTRS flows 45lb/min where as the 18g flows ~42lb/min so thats my explanation.

When my cefiro (SR) had the 18g on it, it happily held 20psi to redline. I read somewhere that they flow 600cfm, which is quite a large number. I still think there are issues here that the comp wheel can't be blamed for.

_________________
Disclaimer: I actually DO know everything

Sil80 - SR20DET 231rwkw
Silvia Race Nugget - SR20DET 225rwkw
Stagea - DeathWagon - RB25DET 185rwkw.

My Lame Gallery: http://www.toomuchboost.com/gallery/main.php

Yeah. Might play around with the cam timing. Its on -2 degree retard atm. Or I got a boost leak that I can't find! Hehe.. ok back on topic...

what was that again

TMB i forgot your car was running higher comp, that would make a difference. with the manifold, if the turbine is the restriction i cant see how a better flowing manifold will make much of a difference, but anyways

i thought the 3071r had a bigger compressor, is it the same one as the GTRS ?

The 3071 is a 56 trim IIRC, which is a bit bigger than GTRS

_________________
Disclaimer: I actually DO know everything

Sil80 - SR20DET 231rwkw
Silvia Race Nugget - SR20DET 225rwkw
Stagea - DeathWagon - RB25DET 185rwkw.

My Lame Gallery: http://www.toomuchboost.com/gallery/main.php

The 56 trim according to Garrett flows on par with the 52 trim but the 56 does it with 5% better efficiency, which is next to nothing really in the real world.

GT2871R COMPRESSOR TURBINE
Turbo CHRA
472560-15 446179-67
Wh Dia Trim A/R
Ind Exd
51.2mm 71.0mm 52 0.60
Wh Dia Trim A/R Type
53.8mm 76 0.64 Wastegated


GT3071R COMPRESSOR TURBINE
Turbo CHRA
700382-3 700177-3
Wh Dia Trim A/R
Ind Exd
53.1mm 71.0mm 56 0.50
Wh Dia Trim A/R Type
56.5mm 84 0.64 Wastegated

_________________
I didn’t break it, I just modified the operational status...
There are 10 types of people in this world, those that understand binary, and those that don't.

which cam is that?

Give it about 4° (crank) advance on the intake and 2° retard on the exhaust and it should work pretty well (it'll die off right up the top, but give a much wider power band)

_________________
The Engine Whisperer - fixer of things

I thought about this after the conversation we had the other night and it doesn't quite add up.

I got a bit of paper out and worked out one bit of it though. I had the intake and exhaust arse about, I thought advancing the intake cam reduced the overlap it doesn't it does the opposite it increases it.

At the same time it closes the lobe centres angle which typically makes better power but makes it more peaky and makes the power band narrower.

But what you suggested above does actually spread the band (slight drop in peak HP) so I am a little confused.

_________________
I didn’t break it, I just modified the operational status...
There are 10 types of people in this world, those that understand binary, and those that don't.

HKS Step 1s, on an S14 so its only the EX side I'm messing with. But whether -2 has the same effect as on the S13s I'm not sure.

1802Go, not sure what you are saying with the Garrett specs?