[Mk2] [Turbo] rev 2 mods and fueling

[karlz0r]

Im currently running 1 bar of boost on my ct26 with a decat intercooler intake on my rev2 ive got to change my headgasket so will uprate to a mls rev3 or Cometic and do my cambelt and bolt my ct20 on.

Im aware of the injectors are maxed out at 16psi and got a modded fuel rail that has been honed out to 8mm with my mines ecu that is meant to lean out the fuel mix would some supra 550's or 540 gt4 level out the fuel mix and not run to rich if i was running 18psi ?

Cheers Karlz0r

[Peter Gidden]

If you fit Rev3 injectors you'll be overfuelling by about 25% ALL of the time.

Suggest you fit your other mods and have a dyno session where your A/F ratio can be checked properly.

[karlz0r]

Is that due to the mapping of the rev3 ecu ?

[Peter Gidden]

Is that due to the mapping of the rev3 ecu ?

Yes. The ECU is programmed to deliver fuel by duty cycle. It doesn't know you've increased injector flow by circa 25%.

[karlz0r]

Ahhh explains it would I have to do a rev 3 swap or repin ecu to suit the rev2's harness ?

[Peter Gidden]

Ahhh explains it would I have to do a rev 3 swap or repin ecu to suit the rev2's harness ?

Yep. With Rev3 ECU and Rev3 injectors.

[craig]

I have a full rev3 turbo wiring upgrade for sale

[karlz0r]

Thanks for the advice peter, ill see what the 20b does on 15-16psi when i get the gasket done.

If i had the spare cash to hand i would swipe it from you red and palm your hand with silver. thanks for the heads up thought

[Turbonoz]

I've got a book here with a chapter on the 3SGTE detailing various tuning stages from stock to a 2.2 stroker. They managed 330rwhp (approx 395hp @ fly by their calculations) with the stock 440cc injectors in a dual-feed rail. Bear in mind this is USA hp....

You can fit 550s with the use of an SAFC, but you also need an adjustable FPR to drop the pressure so that the ECU doesn't advance the timing and grenade your engine. I've not personally tried this method, and it doesn't sound optimal to me. But it's cheaper & easier than a Rev3 conversion I guess.

I've personally ran 1.35bar on a CT26 on the stock ECU and fueling was spot on at higher revs (11.5:1 AFR). Stock 440cc injectors, stock fuel rail, 255lph pump as the OEM item was dying.

[Peter Gidden]

but you also need an adjustable FPR to drop the pressure so that the ECU doesn't advance the timing.

Can you explain how the ECU advances timing based on fuel pressure?

[Turbonoz]

but you also need an adjustable FPR to drop the pressure so that the ECU doesn't advance the timing.

Can you explain how the ECU advances timing based on fuel pressure?

Sorry, I didn't write that very clearly. It won't due to the fuel pressure, but from the SAFC fudging the load signal, apparently.

Fitting 550s will, as you said, cause it to overfuel throughout. To combat this you could adjust the SAFC settings, but this will cause the ECU to advance the timing. Hence, you reduce the fuel pressure (which in itself has it's own consequences) and then dial in the SAFC to 'fine tune'. In the loosest sense of the words.

Apparently....

[karlz0r]

i took her mister 2 down to my local dyno today and she was running pig rich black smoke at 15psi made 236bhp @5344rpm and 247lbs ft @ 3627rpm

check out my graph


any inputs to improve this would be helpful hopefully get my ct20 bolted on soon enough

[Peter Gidden]

i took her mister 2 down to my local dyno today and she was running pig rich black smoke

any inputs to improve this would be helpful hopefully get my ct20 bolted on soon enough

And this is on stock Rev2 with stock Rev2 ECU and fuel setup?

If so i'd be solving the problem before doing any more mods.

[karlz0r]

its on the mines ecu decat intercooler stock fuel system with mbc

[Driftlimits Performance]

I've personally ran 1.35bar on a CT26 on the stock ECU and fueling was spot on at higher revs

And inlet temps were.... a million degrees!

ct26 over 16psi becomes a hairdyer. Just look at the efficiency charts and you'll see 1.35bar is way out! Certainly not something I'd recommend to the masses.

[Turbonoz]

I've personally ran 1.35bar on a CT26 on the stock ECU and fueling was spot on at higher revs

And inlet temps were.... a million degrees!

ct26 over 16psi becomes a hairdyer. Just look at the efficiency charts and you'll see 1.35bar is way out! Certainly not something I'd recommend to the masses.

No. They weren't. Search my posts, intake air temps were posted, and so was my spec. Do you actually think I was running that much boost on a stock intercooler or something?

For the umpteenth time, my CT26 did not become anything over 16 psi. If it had suddenly "become a hairdryer", I would have not bothered running that amount of boost. If IATs were too high, I simply would have turned the boost down It was an experiment before I fitted a GT35 (which in fact became the T78 I run now)

Oh, it was running MORE than 1.35 bar. That is just what it held up top. Another poster on this thread ran their CT26 at 1.5 bar for some time. No doubt with all the right components in place to make running such 'high' boost levels worthwhile.

I've been searching for a compressor map for the CT26 for a long time to no avail. Please post one on here.

[karlz0r]

i took her mister 2 down to my local dyno today and she was running pig rich black smoke

any inputs to improve this would be helpful hopefully get my ct20 bolted on soon enough

And this is on stock Rev2 with stock Rev2 ECU and fuel setup?

If so i'd be solving the problem before doing any more mods.

when i took it out the other day and my friend was logging the boost pressure and on my dyno chart about 5.3-5.4k is where my boost starts tailing off and im dropping to about 12psi normal ct26 but when i get the ct20 bolted on it should sustain 15psi throughout the rest of the rev band and the fueling should not be going richer and should be producing more power as ive got more boost above that part of the rev band.

Am i correct in what im saying peter ?

And take it back to be dynoed and see what the afr readings are like.

[Turbonoz]

Every Mine's tune I've seen for the various Nissans I've worked with are plenty advanced over the stock OEM JDM maps which already more advanced than European OEM maps.

Don't let it get any leaner in the mid-range (see the peak at 4400 RPM, Test 2) unless you know what you're doing.

Running more boost where it's rich will indeed lean out the AFRs. At high boost on a CT26 & stock fuel system, I was running lean top end due to the fuel pump, either due to old age or it simply couldn't supply the fuel.

[karlz0r]

From what information ive got about from the internet and the previous owner was that the ecu Removes fuel cut, raises rev limit to @8k rpm, more aggresive fuel map, mapped for running 1.2bar(18psi).
timing should be set to 8 degs though thats all i was told

I see so you think i could be running to much advance and need to retard the timing ?

When I had the car dyno'd the guys there pointed out that is where it was running sweet spot 11.5-12 he said with a better turbo and run a little bit more boost it should be all good.

Im basically planning to run 15psi on the ct20 and where my 26 is dying off it should hold boost and produce more power without leaning out and have it dyno'd again

[Turbonoz]

From what information ive got about from the internet and the previous owner was that the ecu Removes fuel cut, raises rev limit to @8k rpm, more aggresive fuel map, mapped for running 1.2bar(18psi).
timing should be set to 8 degs though thats all i was told

I see so you think i could be running to much advance and need to retard the timing ?

When I had the car dyno'd the guys there pointed out that is where it was running sweet spot 11.5-12 he said with a better turbo and run a little bit more boost it should be all good.

Im basically planning to run 15psi on the ct20 and where my 26 is dying off it should hold boost and produce more power without leaning out and have it dyno'd again

I couldn't tell you if you're running too much timing, it's just something to be aware of running a JDM tune meant for JDM fuels over here in the UK. I know we've got Momentum99 & VPower, but I've seen some truly dangerous maps from the Far East.

11.5-12 is a good solid range for a "safe" AFR.

The issue you may face is if it leans out anymore in the mid range. I don't know how much more air the CT20 flows at 4400 RPM and how the ECU will respond in kind. You're more likely to experience knock in the mid range as the load ramps up sharply, so just keep an eye (well, ear) on it.

Did you mean "more aggressive timing map"? Fuel maps aren't known as aggressive, but timing maps are.

Check out this thread here I started with regards to the 8k limit and possible limitations:

http://www.imoc.co.uk/forums/viewtopic. ... highlight=

I have personally run mine up to 7800 rpm with no issues. Consensus appears to be to fit ARP rod bolts for 8k rpm limit. I am still running stock everything.