As some of you may know recently went back to flea FC PERFROMANCE to get remap after fitting gt30 and also ended up fitting bigger injectors.

heres pics of graphs but as you can see ive got boost leak/or problem that currently trying to diagnose due to on the boost graph you can see my boost hits 1.4/5bar then starts tailing off very quickly but its very wavey/Pulsating like and can be felt via driving.

im happy with the new figures but annoyed as to what is causing the pulsating boost.

what boost controller do you have?

blitz sdi 3, dont you have the same nigel?

Yes I do - what gain settings are you on for your various channels?

same gain setting for all and its quite low i think. will go check right now

Luke what on earth have you done to your sig lol!

right checked gain setting and it was at 18
whilst it was at this it was spikeing to just over 1.5bar then pulsating its way down. the boost number is 63 that is what?

anyway turned the gain down to 7 and went for a drive and it seems im not hitting full boost till way over 4000rpm surely i should be at 1.4bar before 4000rpm even on the gt30??

Nigel what are your exact settings for your blitz at different boost levels.

@didcoop: Oi i thought it was ok. were not all photoshop genius's like you mr but if youd like to alter my sig for me properly i wont complain.

Just to confirm, it's nnot the Blitz as it still fluctuates with a manual boost valve, has to be a leak somewhere.

Luke - until I get back to the car, I'm not sure, but they will be something like this:-

Channel 1 - Set 1.0, Gain 15
Channel 2 - Set 1.2, Gain 12
Channel 3 - Set 1.4, Gain 10
Channel 4 - Set 1.8, Gain 7

If you have the 'Set' setting represented as a big number (like your 63 value) IIRC, this is actually expressed as a percentage of the maximum scale you're Blitz is set to (my scale is set to 2 bar, so 63 would be equivalent to about 1.3 bar)

I can't remember which way it goes now, but one method is classed as Auto, the other as Manual. I *think* the bar setting is Auto.

On mine, I have a bigger gain setting for lower boost levels - it allows the turbo to spool up quickly, but doesn't give much of an overboost

At high boost, the gain setting is much lower (single figures for the top channel, maybe even for channel 3 as well - can't remember)

You need to experiment, but I would be surprised if you ended up with a gain setting in double figures for your max boost channel

Don't forget you can switch the Blitz to a line graph of the boost, so you can actually see the boost 'curve' as you drive - one click of the wheel from the standard screen - its a great way of working out how much your boost drops off (or fluctuates)

just had chat with flea, its definatly not the blitz as i also thought from the dyno when we totally bypassed the blitz using manual bleed valve and it still did it.

it seems there has to be a boost leak which is only leaking boost under pressure from around 1.1bar +

in that case, check your intake rubbers and oil recirc non-return valve

oil return thing is fine i done the test by trying to blow down it and no problem at all, doughnuts have been replaced too

is this a new turbo?

Ive had SEVERAL GT series turbos with actuator issues causing the boost to tail off rapidly.

also at that high boost id recommend blocking off the PCV (positive crankcase ventilation) valve.

yes it is the gt30 rog, what will blocking the pvc help by doing soo?

actuator issues? explain more please. anyway of me telling

Luke i can see you have reached your maximum power at approx. 6600 RPM. On the graph boost i can see you had 19 psi = 1.35 bar at 6600 RPM.

So you have 356 BHP at 6600 RPM with 1.35 bar.

My question is : do you think you can produce more BHP without the leak but still at 1.35 bar?

It's probably a silly question but for me 1.35 bar is 1.35 bar. For example, if you set your blitz at 1.5 bar and have only 1.35 because of the leak i imagine you will have the same power if you set the blitz at 1.35 but without leak. Do you know what i mean? Is my theory right guys?

Hi,

Couple things wonders me here. Power and torque readings.

My friend had RR on Tuesday with his GT3071R and he used also 1.35 bar boost through the run. Whole session taped, so he could check the A/F and boost readings from Apexi AVC-R and Innovate LM-1.

Anyway with 1.35 bar he received 433 bhp / app. 6500 rpm and 360 lb-ft of torque in 5800 rpm. And in 7150 rpm he still got 425 bhp.

His problem in RR was and is too small exhaust pipe (2 x 2") with three silencer, which stuck totally the engine in high revs.

Wheel power was some 380 bhp on his run.

So, quite big difference between these two cases.

- Jari -

PS. From where the measured boost was taken? From turbo, from intake manifold?

Bit of a silly question, but why is the torque all up the top end,

or is this just how these gt30's deliver it

Ben

good point jari, my exhaust id only 2.5" from catbback with decat! hayward & scott 3" downpipe tapers to 2.5" where meets decat pipe.

What downpipe is your friend running?

Jari, what is his full spec because that is quite exceptional results. I don't know of any other coupe that can achieve such power and torque with such low boost. Indeed yur car made less power and torque with more boost did it not? What injectors does he have and has it been mapped?

Hi Flea,

I have acheived twice +400 bhp (408 and 410) with boost app. 1.32 ... 1.37 bar, these according to the Apexi AVC-R.
Peak torque in my case 510 Nm (376 lb-ft) was achived with 1.52 bar.

Okay, my friends specs at the moment:
GT3071R. 0.86
C&B cams, special timing.
Big valve head (34 mm / 28 mm).
Forged internals
3.5" downpipe
2 x 2" exhaust pipe, decat
OE injectors & 4 extra injector, pressure (boost) controlled
FMIC
Walbro 255

Only "sh..t" in his setup is really the exhaust pipe, which is really restrictive with three silencer.

Now he will try on coming Saturday, run quarter mile without exhaust pipe, so only downpipe installed. The track is not the best possible, but it will give some idea of the exhaust pipe restriction.

-Jari-

PS. I will build a identical setup in some point of summer (if only I have time ), except I will run with bigger injectors + 3" exhaust pipe.

Interesting setup, the biggest difference with Luke being the big valve head and the turbine housing. The 0.86 makes a significant difference allowing a fair bit more airflow at the top than the 0.64, although you sacrifice a little bit of driveability on the road.

So how are the extra injectors being controlled and why did you go with this route?

why would you only have 4 extra injectors on a 5cylinder car? I'm confused

Hi,

4 extra injectors are located before throttle body and they are controlled through pressure valve. Each injector has own valve, which can be adjusted separately to what ever boost.
The injectors are from Bosch and have a direct hose connection behind the injector.
For example there is one, which open in 1.2 bar.
Second in 1.4 bar etc.

Personally I don't like that kind of fuelling, but it has been working now over two years.
Idea of this is that you can use the car normally in every condition through out the year, cold starts etc. Therefore he wants to use OE injectors as base situation.

-Jari-

hmmm so quite a bit difference really id say 3.5" downpipe/head/0.86ar

i know mine has much more capability once issues are sorted i just hate trying to find the causes

The fuelling system on the rx7 works in a similiar way, with 2 primary injectors and 2 secondary, the secondary rail only kicking in when the AFR starts to lean out.

Yipeee found my boost leaks need to get back to leighton and back on rolling road

nice one luke

Any thoughts on what it will make when it goes back on the rollers?

not really buddy, maybe 20bhp more maybe only 10bhp definatly make more tho

how yours buddy? must of been different getting back into it at 170bhp more lol

Is the boost holding nicely now then? Have you got Flea on speed dial?