Good Power With Low Boost & Standard Inject&fmic

[fsmout]

hi everyone

Well after some crazy finance stuff went down with my last GTR & subsequent sale before xmas ....i took delivery of my new GTR on thursday...and im happy to say that its all going well so far!! its a 1990 model built at the Tomei workshop.

First stop was Mercury Motorsport for a tune check to find out how its running (air fuel etc)..as it has got a rytech computer and i dont want to blow it up....it pulled very nicely given its running 1 bar (just) & standard intercooler & injectors. Running a little rich dipping into the lower 10s on the dyno but overall a good tune (nice & safe).

Is anyone else running this kind of turbo? and has had experience increasing the boost a little?

cheers,

Francisco

[Dee 33]

Youch. Smooth tune but damn that power comes on late. By the looks of the graph that turbo has plenty more in it as it's still racing upwards at 9krpm.

More boost will help move that curve to the left a little. I'd say it's got plenty more left in it but I can't comment through experience as I haven't used that turbo myself.

[R31Nismoid]

6500rpm and you dont even have over 200rwkw...

And a 50degree intake temp?

geebus.

Something doesnt look right there at all. A stock turbo'd GTR would eat that for breakfast

What spec are the t04s?

[benl1981]

As a comparison - RB25DET power levels at 10psi (tuned powerfc)

3000rpm 100rwkw

4000rpm 116rwkw

4500rpm 134rwkw

5000rpm 153rwkw

5500rpm 164rwkw

6000rpm 170rwkw

6500rpm 172rwkw

My stock gtst (10psi) is making more power up to about 6200rpm - that must come on like a light switch!!! Huge turbos??

Must push you back in the seat.

Edited January 31, 2006 by benl1981

[MattSR]

Standard intercooler and injectors?

Hmm

[Fixxxer]

Whats with the boost graph? Ramping up to 12psi, then almost plateauing and very slowly creeping up to 15psi. Very weird.

Are dyno's of GTR's always done in 3rd gear?

[Cubes]

N1 injectors?

[krzysiu]

Thats a painful graph. Big top power but its pretty much useless power

[Craved]

wonder what size the rear housing is, cos that boost curve looks very similar to mine with a 1.12 rear housing and a faulty WG.

[SKY 34]

wait..how does your car go to 8400rpm?

[R31Nismoid]

Thats probably near where the limiter comes into it and spoils the lag party

[fsmout]

yeah the 4th gear power curve was a little flat, but im not trading for a GTST anyday!! LOL

i think the boost creep is normal for a standard wastegate spring & no boost controller?

yeah from what i have heard, the injectors must have huge pressure behind them (fuel pres reg & big pump). Apparently they use this to create a cleaner combustion??

i would say that the injectors may have to be highflowed..

i had ball bearing N1's(r34) on my last GTR and this setup definitely doesnt have as much mid range, but the lag isnt to bad.

ultimatly it needs a tune & injectors to pull the tune into shape

[Beer Baron]

you definately need to look at boost control (or a different turbo) as you are only reaching 15psi at ~8300rpm. a good set of twins, or a good single that can make over 300rwkw will hit 15psi around 4000 so there is a huge difference there.

[MattSR]

If its taking 8500 to get the 1 bar then you have serious tuning or mechanical problems

[R31Nismoid]

The lag isnt bad? i couldnt live with the un-responsiveness of that turbo.

Its not even making 300rwkw @ 8000rpm.

My advice, take a ride in a car with GT-SS or 2530's etc.

Cars which have 300rwkw between 3500-4500rpm and hold it to redline.

Or even a well matched single like a GT30/35 etc.

I agree with MattSR, something isnt right at all.

Plus the Intake temps are 50deg, 3rd gear.

Too many wrong things there

[benl1981]

That's a very narrow powerband. I would run you in my gtst. You couldn't keep the car in that powerband. You need atleast a 3000-3500rpm window where you have good power.

[fsmout]

yeah R31Nismoid it was a hot day, driving it al day in 35 deg heat before the run, pretty safe to say it was quite warm under the hood even when the fans were put on it.

as stated above my last GTR had a set of lowmount twins that were pulling mid 280's at the wheels, so i am quite familiar with the feeling of more power from lower down in the rev range. im pretty sure that GTSS's & 2530's dont produce 300rwkw from as low as 3500rmp-4500rmp????

even though the graph says it was a 3rd gear run, it was actually a 4th gear run but did actually make 286awkw in 3rd, with a much better looking graph. i didnt get a digital copy of the 3rd gear run, but ill scan it.

benl1981 yeah anytime, r u in QLD? it would be pretty interesting actually. only started giving it some stick since saturday when i found out the tune was safe and havent lined up against anything...

it does seem to me that there may be a boost problem....it has one of those apexi exhaust control valves..i know people have problems with them all the time.

[R31Nismoid]

oops, meant 250rwkw, moving along

here is 2530 - 300rwkw 4800rpm

http://image-cache.skylinesaustralia.com/f...-1134731997.jpg

Not trying to be rude in anyway here, but you definately have something wrong somewhere, even though the T04s is really old technology and un-responsive.

I think we are all trying to help you see that.

Your average power from 4000rpm say we work from

4000rpm - 65rwkw

5000rpm - 100rwkw

6000rpm - 160rwkw

7000rpm - 215rwkw

8000rpm - 270rwkw

8200rpm - 292rwkw

Making it 183rwkw - not that flash

Or start @ 6000rpm, making it 2200rpm of useable rpm, still only 243rwkw av. That is extremely low.

No amount of extra boost winding in there is gonna make it come on a earlier.

It's either the tuning or something mechanically isnt right

A car with 2530's making 300rwkw from 4800rpm, upto 350rwkw is going to have an average of GOOD useable av power of 320rwkw from 4800rpm too redline (nearly 4000rpm worth)

Thats a massive difference to say the least.

Im still keen for someone to come out with the t04s specs as i CBF'd filtering through the net for em at the moment

[discopotato03]

I did , basically 60 trim 7/14 blade TO4S compressor in .70 a/r TO4S cover .

Turbine is TO4 76 trim (TO4 P trim) in either .84 or 1.00 a/r twin entry T4 flanged turbine housing .

The compressor looks to have been faced on the inducer blades sort of like the TO4R/Z compressor .

So basically TO4 60-1 with P trim .

Just for the record Garrett is doing what they call T3/T4R BB upgrade cartridges one of which is a TO4 60-1 and P trim combination . Easy upgrade to ball bearings if its what you want . I guess you could look at it as a 600Hp TO4Z with a slightly outdated comp wheel design .

Cheers A .

[warriorbrawl]

Running 10's AFR will not help power at all you could easily be loosing 20~Kw right there. could be a start.

If the tune is done right there is no need to run it so rich it just waste's fuel and robs power.

good luck with sorting it out.