Dyno Run - Interesting Results !!

[Jay95R33]

I got rid of the nasty flat spot !!!

I don't know how for sure, but read on.......

After a recent round of simple mods, I took the car in to see if everything was on track and OK.

Just a bit of background.

Used same dyno. First (lower) run don in winter on a 16 degree day, second was done on a 32-33 degree day. Dyno was run in NON shootout mode, in 4th gear.

Difference between first run and second run was a highflow cat, an adjustable exh cam gear set at 3 degrees retarded, and a different rear muffler.

Plus the ECU was out of the car for a day prior, so it would have reset itself.

Full mods are very simple, 3 inch turbo back exhaust, 12psi boost (see attached sheet) highflow panel filter in stock box, FMIC, adj exh cam gear. Stock ECU, Stock turbo.

The thing I am most happy with is that for reasons unknown I have got rid of the flat spot that most other R33 GTS-t's get. I'm still running the same ECU... The only thing I can see is maybe (and it's a big maybe) it was cause the ECU was reset the night before..

Getting rid of the flatspot has gained me about 35rwkw in the mid range !!!! VERY happy with that.... Up top it's about 10rwkw gained, but it's much smoother.

I might wind the boost up a little cause it's dropping off at the top (see attached) due to the wastegate creeping open at high RPM's.....

The next step for me is programmable ECU..

Open to comments

Anyway, too much crapping on, have a look for yourself....

[MJ]

hey man im no expert but those AFR's look quite a bit out.....im sure with a safc or any other similar device will get some more decent power to fix the fuel mixtures

[3R1K]

Wow, it's pretty low I guess, for 12 psi boost.

My 34 getting 162 kw with 9 psi so I'm not sure man -> my car is slower than 33 dun worry

ask others fellow 33

[Jay95R33]

I was actually pretty happy with the A/F ratios on the second run (the green line).

They stick to 12:1 which is just about perfect, then drop to about 11.2:1 after about 4500rpm.

I could get a SAFC to lean it up above 4500rpm, but there wouldn't be much in it. I think there would be bigger gains in being more aggressive in the timing. But sadly we don't have much control (almost zero control) over the timing.

I did adjust the base timing from 15 degrees to 17 degrees and there was absolutley no difference in the runs which supprised me..... Maybe I should've gone to 20 degrees or something ??

J

[benm]

Difference between first run and second run was a highflow cat, an adjustable exh cam gear set at 3 degrees retarded, and a different rear muffler.

What sorta power were you making before these mods ?

[Jay95R33]

P.S. - I'm not too concered about the overall power cause this dyno is known to read low and every dyno is different !!!

But the interesting thing is the (lack of) dip in the second run.

J

[Jay95R33]

Benm - the red line is the original dyno run from about 7 months ago that didn't have the highflow cat and adj ech cam gear.

So the red line is the old power, and the green line is the current power.

J

[benm]

*smacks himself in the head* .... of course

[Jay95R33]

[Steve]

Nice result, reduction in back pressure is obviously helping alot

[strutto]

The AFR's look pretty good to me... Probably a little bit more power to be had up top. Once the boost is stable up high, the AFR's up high will probably get richer though...

Question... Why is it running leaner now?

[Busky2k]

You know, that giant flat spot looked exactly the same on my SR20DET. Im pretty sure it was because the ECU was pulling timing at that particular point. After a ECU reset and resetting the timing, it never came back again...

Also that extra power came mostly from the leaner AFRs I believe.

Oh btw, you Skyline guys must have quite a shorter diff and 4th gear. On the rollers, my car goes pretty close to 165kmh in 3rd gear!!!!!!!!!!!

Hmm If i put a skyline diff in my car... *GRIN*

[SLY33]

busky i thought they shared the same 4.1ish ratio diffs and similar gear ratios. 165km is pretty fast for 3rd.. maybe yours is special

[Busky2k]

Nah, aus spec cars defintely have a diff ration of 3.7. Jap specs maybe closer to 4 (like 3.9). Its definitely right tho, as about ~40-50m before I cross the line on the strip, I shift into 4th.

[RB20LagWagon]

r32 manual diff is 4.3 r33 is 4.1 as is s14.

[Jay95R33]

Steve - Yepp, I think your right, better flowing uptop is helping things.

Busky2k - I'm supprised that a reset got rid of the flat spot !! If it comes back again you know what I'll be doing BTW: 2nd gear goes to ~105km/h, 3rd gear only goes to ~140km/h, and 4th tops out just before 180km/h, so the gearing is fairly close...

[Busky2k]

RB20LagWagon, the S14 is definitely not 4.1 dood.

The auspec workshop manual clearly states its 3.692 to be precise! Perhaps the JSpec ones are 4.1?!

Jay95R33, what are the ratios of your gearbox? I'll state what the S14 one is;

1st- 3.32 (~65kmh)

2nd- 1.90 (~113 kmh)

3rd- 1.31 (~ 163 kmh, everyone ive dragged always shift into 4th way before I do)

4th- 1.00 (no idea, never gone that far, but it hits the limiter on the dyno)

A skyline diff would do wonders on the strip in this car I reckon....

Btw, Im suprised a reset worked aswell, but I also reset the timing at the same time, as it was like 5 deg overadvanced. I think that was what really fixed it. Btw, I believe you have to disconnect the TPS during idle to get the true base timing.

[Jay95R33]

Not sure on the gearbox ratios for a R33 GTS-t. If it helps any I've got a stock gearbox and the diff runs the stock 4.11 ratio.

Hmm, the first run I did yesterday with my old ECU didn't have the dip, and that was before we advanced the timing to 17 degrees. So in my case I think it may have been just the reset that got rid of the dip... Not sure...

Wierd how advancing the timing did nothing. The CAS is definatly rotated more than it was before, and at idle it showed the increase in base timing, just didn't do anything on the dyno run...

At 15 degrees and 17 degrees the two power lines were sitting right over each other.

I suppose that it's good that the car can pull off a few full power runs and not loose even 1rwkw Nice and consistant power, even on a 33 degree day !

J

[EnricoPalazzo]

my car can get over 190 in 4th.

[whatsisname]

An R33 GTS25t is "capable" of over 200km/h in 4th. It has the gearing to do it. 7000rpm in 4th is 204km/h, before you factor in drag.