R34 Gtt Boost Cut

[gts4-skyline]

I have just had my car on the dyno today, and was told it was hitting a boost cut at 12psi. I thought the cut would have been higher than that. Can anybody comfirm what the boost cut is so I can investigate further if it isn't.

I ended up getting 208 rwkw at 5615rpm on 10psi with a 2 3/4 cat back exhaust, k&N panel filter and a SAFC II, so I am happy, but 12psi would make me even happier

Cheers

Glenn

[ecl]

tats a pretty nice figure with just exhaust, filter, safc and 10 psi

satanic on this forum had 194 or something with the same mods except he had FMIC and just a catback so i guess its pretty similar

i think some ppl experience boost cut at anything above 10 with the standard ecu

i thought the safc would remove the boost cut? hmm, i guess im wrong then

[Abo Bob]

Sounds like a pretty happy dyno but just the same it sounds alright to me. Knowing what I know now (as opposed to before I went too far) I would sit back and accept that as pretty good and enjoy it.

Post your dyno sheet if you like and we can comment on that.

[gts4-skyline]

yea, pretty happywith the numbers, but I have heard of people running 12psi without a problem.

It was on a dynapack hub dyno which usually runs higher than rolling roads.

Here's the dyno sheet

[Abo Bob]

It looks like it's surging as it is.

[ed]

damn your power is dropping off early....is that what surging does abobob?

weird how you have a 2.75" exhaust.

first i've heard of one on a skyline.

[gts4-skyline]

What is surging, and what would I do to fix it?

[Bass Junky]

Rich, Retard, Rich, Retard.

Repeat.

[Bass Junky]

I mean Richen the fuel, retard the timing, recover.

repeat.

I didn't want you to think I thought you were a rich retard!!!

Rich/Retard is what happens when the stock computer sees higher than expected airflow/boost etc.

[Abo Bob]

It sort of looks like you are running higher boost as it is.

Surging is where you are putting the turbo out of it's efficiency range. The car surges forward and the boost curve is like a wave.

[mad34]

Hey guys what does the standard boost gauge go up to??

does +1 mean 14 or so psi??

is it fairly accurate?

mine goes up to about 2mm from the +1?

roughly how much would it boosting do you guys reckon??

my gtt when fully boosting sometimes pops a little at around 5krpm could this be the boost cut??

i really would like to try and find out what is causing this before i go and replace coils and get safc etc??

[NJR 34GTT]

That's not boost/fuel cut. Boost fuel/cut will make the car jerk and will throw you a bit forward if you are accelerating hard enough when it does it.

Yes 1 on the stock boost gauge is approximately 14psi.

The popping is unburnt fuel in the exhaust and nothing to worry about.

Your graph looks very similar to mine when it was tuned poorly running 13-14 psi of boost. You may want to get that checked out.

[satanic]

Another R34GTT tune... 208rwkw is a very good number! I presume your car is a manual? This may explain the variance of 13-14kw between yours and mine since we have pretty much the same mods.

However, if you look at the graph in my blog, you'll notice that curve does not have any 'kinks' in it... maybe if you sort that out you'll be looking at 220rwkw which should be the correct difference between auto and manual.

[NJR 34GTT]

Satanic, hub dyno, reads higher than a roller dyno. Still a very good result.

[satanic]

So how much difference is there from hub to roller?

[choyda]

Hey guys what does the standard boost gauge go up to??

does +1 mean 14 or so psi??

is it fairly accurate?

mine goes up to about 2mm from the +1?

roughly how much would it boosting do you guys reckon??

my gtt when fully boosting sometimes pops a little at around 5krpm could this be the boost cut??

i really would like to try and find out what is causing this before i go and replace coils and get safc etc??

<{POST_SNAPBACK}>

Sorry to sort of diverge from the topic but is yours a series 2 R34 because of the R34 GTT's I've seen around here (QLD), the series 2 cars seem to boost close to the +1 but the series 1s go to about the 3/4 line (the mark before) and rarely over that.

[mad34]

Sorry to sort of diverge from the topic but is yours a series 2 R34 because of the R34 GTT's I've seen around here (QLD), the series 2 cars seem to boost close to the +1 but the series 1s go to about the 3/4 line (the mark before) and rarely over that.

<{POST_SNAPBACK}>

mine is a series one

with exhaust fmic airfilter.

[Bass Junky]

I had a boost cut of my own last night.

Blew a turbo!!!

No boost for me!

Until the highflow goes in of course!

[gts4-skyline]

Thanks for the replys, I have found there was a split pipe to the boost controller, which was giving the cut out, and probably causing the drops in the power. So I will wind the boost back up to 12psi and do another run on the dyno when I can afford it.

[gts4-skyline]

If I was to fit a front and dump pipe would I have to get the safc retuned again?