My Custom Gt28 Turbo

[jmac]

out of interest: here's a "pre mods" power run. 198.5 rwkw.

spec:

pod

full 3" exhaust (BATMBL split dump/front/cat and Blitz cat-back)

gt2876r hybrid turbo as above

turbotech bc running ~11PSI

everything else = stock

it's obviously running pretty rich and i guess bumping into the R&R from the stock ecu?

anyway should be interesting once everything's done. waiting for the powerFC to arrive then the fun begins. final spec will be:

pod

full 3" exhaust

gt2876r hybrid

14-16 PSI

powerFC

blitz LM FMIC

bosch 040 pump

nismo 480cc injectors

Z32 afm if needed

who knows what power. i think anywhere between 230 and 260 is a good guess. a nice chunky torque curve is what i'm after. thanks for your opinions too guys, it'll be interesting to see how this turbo goes.

EDIT: forgot about 040...

Edited December 1, 2005 by jmac

[Abo Bob]

Yeah it's obvious you have the stock ECU there. Should be interesting.

[Cubes]

How does it spool?

With the small T28 turbine wheel it should be quite a nice street turbo.

[jmac]

well i think it's pretty good. coming on strong by 3500rpm. hard to subjectively say though not having felt the characteristics of anyone else's. to me it's not that much laggier than the std turbo. so frustrating cos just as it starts to boogie you can feel the ecu freaking out and pulling the spark out...

[Cubes]

I 'THINK' not know. :S the difference between this and say a GT3076R (same comp wheel larger turbine wheel) would be that the GT3076R will make less boost at the lower rpm's. In other words it will snap on a little harder, the GT2876R being a little more progressive and offer more boost at lower rpm's.

I think... maybe you can confirm that it does? Where does it start to make boost?

There was an R33 with a GT28 (I don't know the specs) at our last dyno day, that made a solid 245rwkw.

http://www.skylinesaustralia.com/forums/in...opic=87573&st=0

Edited December 1, 2005 by Cubes

[BHDave]

There was an R33 with a GT28 (I don't know the specs) at our last dyno day, that made a solid 245rwkw.

<{POST_SNAPBACK}>

I know of one with a 2871 making about the same

[Cubes]

What boost was the 2871 running?

[jmac]

I'll be able to give you a definitive answer next week - PowerFC arrived today and have booked the tuner+dyno for Monday. :lol: Will post any graphs I can lay my hands on!

At the moment it's beginning to spool at 3200rpm and really gives you a fair shove in the back at 3500rpm... Boost gauge reads 11PSI. Then at about 4500rpm (especially in 1st and 2nd gears) the ECU spoils the party.

So once I get this sorted properly with the PFC and the injectors that're sitting on my coffee table at the moment I'll post and try to describe how it goes as best I can.

[Dale FZ1]

Looking forward to it.

The PFC gives you the freedom you need to make the hardware changes work for you.

Please make sure you post up the results.

cheers

[jmac]

Ok so had some tuning done today. There are still some issues with the car in its current state:

- AFM maxing out to 5.0V (Z32 AFM on the way)

- boost spike from Turbotech BC (PowerFC boost control kit on the way)

But otherwise here's the spec:

No-name-brand pod filter

MTQ GT2876R hybrid

Blitz LM FMIC

Bosimporting split 3" dump

Catco 3" metal cat

Blitz 3" Nur Spec cat-back

Apexi PFC

Turbotech BC

Bosch 040

Nismo 480cc injectors

Result was 226.5 rwkW. The tuner thinks there's a bit more in it but we need better boost control and better AFM resolution to get there.... which is kinda what I *thought* might happen.

As for what it's like to drive, well... it's FUN, especially that lovely spot at 3500rpm where everything starts to happen. From that point on it's linear and IMO spools quickly. It's got HEAPS more midrange than before which is what I was after.

Just gotta wait for the bits to arrive so I can get this 100% where I'd like it....

Comments etc welcome!

[Dale FZ1]

Looking very nice...

I see that boost spike as it comes on - maybe not ideal? Did that cause any tuning problems?

Also interesting to see how you have a very wide plateau of max power; what does the shape of the torque curve look like? and how does it feel in the higher revs beyond that 3500rpm point?

Also is there any feeling of lacking response or engine flexibility right down low (eg. trickling along in 3rd or 4th @ 1800rpm and squeeze the throttle) compared to stock?

You should be happy overall at this point though.

cheers

[jmac]

Speaking to Paul this arve the spike itself didn't cause problems, it's the adjustment of the actual little Turbotech valve that was problematic - half a turn takes you from 10PSI to 17PSI...

Initially we ran into problems, kinda like a random misfire/stutter between 4000-5000 rpm. Apparently my coils are ok and it has a new set of plugs so the likely thing is maxing out the AFM.

If it persists I'll go for the Spitfires anyway, but first I think the Z32 AFM and boost control kit should go in and see how it runs then.

The torque curve was very broad and flat too. Didn't get a printout (dynos are not the best at measuring this apparently?). Yeah after the turbo spools if just feels linear, power builds progressively. Things can get a bit out of hand in 1st gear but I mostly hold traction in 2nd - the sticky tyres help!!!

So I'm happy with the result, but not 100% happy overall yet!

[Bass Junky]

you should see some pretty good numbers once the boost kit goes in.

Keep that boost nice and flat, and once the fuel gets sorted out, you can start winding in some boost and making seom decent numbers.....

Farkin..... Having anohter look, if your graph is right, you are making at 100kph, you are making over 200 rwkw...... I don't make that until 135, so boost sure as hell comes on early.....

But, runs are done in third gear that's why.

[Dale FZ1]

Ok, reading between the lines it does come on like an animal and then predictable and obviously fast? I do have to agree there is plenty of meat, very early in the curve. Please give us an idea of what it's like in on/off throttle driving.

Bass how similar to your turbo is this unit (apologies if there's comment on this earlier in the thread)?

cheers

Dale

[Bass Junky]

Dale.

Mine is a GCG highflow R34 Turbo.

[jmac]

I haven't felt any power loss at low revs or on low throttle openings. And during on-off throttle driving it spools quickly, you're not left waiting for 2-3 seconds for the power to come back on. The main thing is if you're going for it then keep the revs above 3000.... but it's not annoying or laggy to drive in "normal" situations at all.

[Dale FZ1]

Thanks jmac. It's good to see you're satisfied with the result to this point. There are many instances where the modifications lead you to having to keep the revs up or down just to avoid lag and/or the massive rush as it all comes on too strong.

My view is that besides being strong, it still has to be streetable (tractable) and not threaten to light the bags/snap sideways any time you squeeze the throttle coming off a roundabout or turning a street corner.

Probably showing my age, and preference for OEM style power delivery, but I have strong recollections (as a spectator) of the Group A Ford Sierra Cosworth RS being "challenging" to drive around windy tracks. That of course was one reason the GTR became so dominant with the level of traction available.

Bass what is your level of satisfaction with your setup and power level?

cheers

Edited December 20, 2005 by Dale FZ1

[Bass Junky]

Dale,

My car is a joy to drive. you can trundle along, getting passed by grannies, without a problem at all. All it takes to make things blur is a downchange to whatever gear 4000rpm is and a bootful of throttle.

I build boost in no time and have a 4000rpm wide power band.

It doesn't brake traction either. Just get's the hell out of there!

[jmac]

My feelings are pretty similar to Bass Junky's. I feel it's about 90% of the way there in terms of the tune but basically it's a versatile car to drive. Keep things below 3000rpm and drive like a Sane Person and it's a relaxing car, with good throttle response and reserves of low-speed torque. Kick it up the arse and yes, there is a "stepped" power delivery at about 3500rpm when it spools but it's not wild and doesn't produce clouds of smoke in anything other than 1st gear.

During the process of doing these mods the point at which it lost a little throttle response was fitting the FMIC. That was one thing I definitely noticed.

Quick question - the misfire I mentioned above is still present but only at 4000 -5000 rpm and only on WOT in 2nd and 3rd. The AFM is definitely maxing out to approx 5000mV but is there any chance this is a coil problem? Visually they look fine (I've seen some stuffed ones off an R33) but I remain suspicious given the descriptions in the coils thread sound exactly like what my car does.

The PFC is not logging big knock values but of course is logging that 5000mV ceiling on the AFM.

I hope it's the AFM... it didn't misfire on the dyno at all, only on the road - maybe because you're sucking more air on the road cos the fan unit they use at the dyno doesn't give you a similar volume of air?

What do you reckon guys? Or is it odds on I'll be stumping up for Splitfires soon?

Hope y'all had a good xmas. Cheers!

[Cameron_Datto]

What spark plug gaps ru using ? Try using .028" if you have gaps wider than this ...