GTi-R hp build

[alphadrex]

I'm posting this up here as well in case some of you are not members over at gtirmotorsport club...

Hello all,

So I need to throw a question out there. I just completed a build on my '91 GTi-R, and just heard from the tuner. My power numbers are drastically different from the results of others/Fusion Motorsport guide. I'll start with the build specs.

-Stock internals
-Stock TMIC
-Walbro 255lph pump
-Deatschwerks 1050 injectors
-NISMO fuel press. reg.
-AMPerformance 3" full exhaust
-Garrett GTX2871R turbo
-Innovate Motorsports PSB-1
-Linq Standalone ECU
If I think of anything further I will add, but this is all that comes to memory...

Was just told by the tuner it made 271hp and 254ft/lbs @ approx. 18psi boost, 92 octane at the wheels. They ran into fueling problems (i.e. detonation) when pushed any further.

These numbers are drastically different than other builds I've seen (Fusion, forum builds, etc...). Is it because my numbers are at the wheels? I know the TMIC will cause higher intake temps, but i was still expecting 350 ish...

If anyone can help me understand this it would be greatly appreciated.

alphadrex

 

[campbellju]

It’s a little low at the flywheel but you were only 18psi and running 92 octane fuel. In uk we’ve always had 95 but most run 97 and nowadays 99.

You are on stock internals so maybe there’s a problem elsewhere causing the knock?

 

[MarkTurbo]

If it's 270 at the wheels that must be around 330 at the flywheel so not too far off where it should be.

What's your ecu set up? Does it still use any of the standard functions because the standard ecu will retard the timing if the knock sensor picks up any det which would reduce the power by a fair bit. I've had it happen on the dyno when my car still had a top mount intercooler.

 

[alphadrex]

I'm definitely jealous of your fuel quality over there, would certainly help my situation here.

As for the ECU, it's a full standalone that, to my understanding, is fully programmed by the tuner retaining none of the original system. Not sure if it came w/ a base map or was built from scratch.

I'm considering putting in a water/meth system to help w/ fuel quality and intake temps. Anyone got experience with that on a GTi-R?

 

[PobodY]

The fuel quality is a bit misleading. - North America uses a different octane rating from the rest of the world so when it says 92 on the pump in the US, that's an Anti-Knock Index (AKI) which is the same as 94 Research Octane Number (RON).
(So 99RON is the same as probably labelled as 94AKI in North America.)

Any chance the problem is with the spark? - What plugs are you using, and what gap?
Are they an appropriate heat range for example?

Personally I don't like the precious metal tips because they're too delicate and prone to fouling. I like a copper core, and I think I'm running ~1mm gap.
If the gap is much bigger the standard coil can't make the spark at full boost, and the power drops off. Much smaller and it's a weak spark, so there's a bit of a balancing act to finding the sweet spot. - An over-simplified explanation is that with every atmosphere of pressure in the cylinder you're doubling the effective gap on the plug.

 

[alphadrex]

Hey PobodY,

I'm using NGK4644 BKR7E. Copper core, gapped to .8mm. Unfortunately I wasn't there for the dyno tune/run, I live approx. 5hrs away.

The plugs I pulled were a 6 heat range, but I thought it would run too cool, so I upped it to 7.

 

[Fast Guy]

Aren't our plugs heat range 7 as standard going to 8s when tuned if needed? 6 is the 200sx plug isn't it?

 

[alphadrex]

Aren't our plugs heat range 7 as standard going to 8s when tuned if needed? 6 is the 200sx plug isn't it?

Hmm, I did a pile of searching, and most of what I found people recommending is the NGK BCR8ES w/ a .7mm gap, but I couldn't find them anywhere except ebay for a crazy price. So I figured I pulled 6s out (previous owner) and forums were saying 8, so I'd split the difference...

If you're certain it calls for 7, I'll mention to my tuner and maybe we can look into stepping up to an 8. What is the standard gap it calls for?

 

[fubar andy]

I ran 8's for 300bhp (fly) on track with a top mount intercooler and had no issues whatsoever.

Those were BCR8ES's.

I'm considering putting in a water/meth system to help w/ fuel quality and intake temps. Anyone got experience with that on a GTi-R?

I wouldn't bother personally, you could re-core the standard top mount intercooler for a more modern/efficient cooler, or opt for front mount if you wanted to go down that route?
I know a few people on the owners club that have gone down this route regards re-coring the standard top mount for better cooling and I've read good feedback.
Other than that you custom make a front mount intercooler system?

Does the AM Exhaust also have the 3" elbow from the turbo?

I woundn't worry too much about the BHP figure, but more about the fueling and detonation you're having.

 

[alphadrex]

I knew that BCR8ES was the plug of choice with our cars, and had hoped to run them as well. However, I did some substantial searching for them (local auto parts stores, online Canadian parts retailers, Amazon, etc...) before picking up the plugs I have. I don't know if they are just not available in Canada or if NGK has discontinued them, but I could only find BCR8ES on ebay from international sellers.

Do you have another plug alternative or cross to another brand that you have successfully run?

The reason I was considering water/meth is to drop my intake temps to considerably combat the fuel quality/detonation issue. The power added is just a nice bonus.

The AM downpipe is 3" including the elbow. That is to say, it is a true 3" w/ screamer pipe from the turbo-back.

As for re-coring, I am definitely interested in doing that. Do you have any info of a core which may work for our system? I did read about it over on GTi-R Motorsport Club, but I don't recall anyone posting actual part #s or a supplier for a new core.

I don't want to change over to a front mount as I have a weird attraction to the stock look TMIC. There's just something cool about it to me. Plus I had my bumper powder-coated and didn't want to hack into it.

 

[keastygtir]

I too would rather re-core the TMIC. Anybody know if a definite upgrade route was ever established?

 

[Fast Guy]

If you're certain it calls for 7, I'll mention to my tuner and maybe we can look into stepping up to an 8. What is the standard gap it calls for?

Yes, if you have a Gtir (54C) SR20DET and not an inferior version then 7s are standard 8s are one step colder for higher power.

 

[PobodY]

There was a great bit written by Ed (I think), who was working for Holset at the time, about water/methanol injection.
I can't remember the whole thing, but I can remember some of the points:

1. If you want the most from the water/methanol, you need to map for it or all you're doing is enriching the fuel without changing the timing.
2. If you have mapped for it, then you need to ensure there's always enough water/methanol in the tank or you're running lean.
3. Whilst there is an improvement to charge temperature, you really need to be injecting a stoichiometric amount for it to work properly. - In short; it probably needs to be controlled by the ECU in the injector duty rather than some other box.

It was enough to convince me that it wasn't worth the effort of setting up my Aquamist system in a daily driver (as it was at the time), but it might be worth the effort in a car used for sprints or drag racing.

 

[alphadrex]

Well, I've emailed NGK and have confirmed that the BCR8ES is indeed not available for sale in Canada. Looks like I'll be ordering off Amazon US.

As for the water-meth system, I'm very much considering it as mine is a weekend/track car, and the power gains are undeniable.

Before going down that road I'll have to do some work on my internals. Main and con-rod studs and so on, maybe full on forged...got the car back today and I'm already planning the next teardown. I think I have a problem. Ha ha.