GTi-R hp build

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

350hp at the fly is around 290hp at the wheels so you're not far off mate. Any idea what our equivalent of your 92 ron? I was running 1.5 bar on top mount on gt2871r on our 99 ron and had around 15 degree of ignition and no knock ( I road tuned it so ignition might be modest). What afr are you running on full boost?

According to Google, 92 octane is about 97 RON. Do you have stock internals and all with 1.5bar? That's about 4psi more than me. I would have to check with the tuner about what the AFR was. Will let you know. So what I'm understanding here is that most of the hp #'s being thrown around are at the crank?

Yeah 1.5 spiking to 1.6 bar all stock On awd system you're losing about 30% crank power. In UK or Europe even you usually give crank hp. From what I remember my car at .8 bat made 280hp at crank 230 at wheels that's on gt2871r

That's pretty wild on 1.5bar. Wonder how long the internals would last on that? Just from running the numbers quickly, you said 30% loss, but you're only sitting at 18% loss from 280 down to 230.

It's my daily I was running it like that for 6 months no problem last week I've change it for my forged lump. If you'll look through the forum there is a post about transmission losses it varies from car to car.

from what I seen 20 to 23% (assuming car setup/transmission condition good) seems reasonably close way get a figure on the R if have use percentage .

Easy way to get about 98% right is this.
Take rolling road hp (kW) made, divide by 2, divide by 2 again, add second divide to first and result is a close as you will get, very good guesstimate.
so.
power atflyw Average for Std Max %loss
Standard hp 220 2 110 2 55 165 33%
kW 165 2 83 2 41 124 33%
power atflyw power atw
Guesstimate hp 350 2 175 2 88 263 33%
kW 263 2 132 2 66 197 33%
power atflyw power atw
Yours hp 467 2 233 2 117 350 33%
kW 350 2 175 2 88 263 33%

Injectors are a little overkill for that setup
Are you still running the standard MAF with the link ECU?

I was thinking that as well at first, but I'm never one to be satisfied with it so I wanted room to expand should the bug bite me.
It is still equipped with a stock MAF, but it's all tuned around the Innovate PSB-1, which is a wideband/4 bar MAP sensor, AFR/Boost Gauge all in one.

Edit: I posted this over at GTIROC as well, and plug heat range and gap came up. For the record, I'm running NGK4644 BKR7E, copper core gapped to .8mm if anyone has experience to offer on that topic.

I had my R mapped back in July at Fusion making 355hp at the crank @ 1.3b. That's with similar mods to yours but using the Nistune with an R35 MAF.
What was your AFR on WOT? What's your base timing set at?

I've ran those plugs as well as the irridium both heat range 7 but had to regap to .6 due to a miss fire under high load.

Well, given what Mr. B. said for average percentages, that would land me in the 338-352hp range at the crank.

Splmum, I'm not sure I follow your math. You said take rolling road hp, does the rolling road measure at the wheels or crank? The only way I can see the calculations working is if you're starting with crank hp (which I don't actually have). Wouldn't a rolling road only give you an estimate of crank hp based on an algorithm anyway?

A great deal of my concern has been put to rest now knowing that the numbers I've been reading are crank guess-timates.

Also, on the GTIROC forum it was mentioned I may want to consider stepping the plug heat range up to an 8. Anyone over here have any experience with this?

NGK BCR8ES. Cheap just replace every year

7s are fine at that power. Plug colour looks spot on.

I always run NGK BCR8ES plugs in mine and never, ever had any issues with them. If you change them once every 10k miles or so you'll be fine. AFAIK they're good plugs from virtually standard boost right up to silly levels

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?

You could try these guys in the UK to see if they would ship to you:
https://www.sparkplugs.co.uk/checkout/cart/

Failing that this NGK chart might help source alternatives you can get over there:

that UK website is actually quite good for finding alternative plugs too:
https://www.sparkplugs.co.uk/ngk-spark-plug-bcr8es

click on the cross reference tab in here ^^^