What am I doing wrong?? VRT advise needed!

[sleepymike 15]

Hi, right basically I seem to be having trouble getting more power from my VRT.

It's just been remapped today and it now has 332bhp at 18psi I was hoping to get more than that but it appears that as the boost is turned up the power seems to go down.

Im still running a dizzy and have been struggling with a misfire at higher boost at high revs but making the gap smaller on the plugs seems to sort it.(planning to convert to coilpack ASAP)

The spec is

Obd1 2.8

K&n air filter

3" stainless pipe into 4" turbo inlet

Gt3076r

Cast spa turbo manifold

2.5" intercooler pipe work

Modified rx7 alloy intercooler

Homemade front short air intake made from 3" stainless pipe

Bosch 440cc injectors

8.5.1 C2 spacer

HKS blow off valve

38mm Tial wastegate

Electronic boost solonoid

Omex management

3" exhaust right through with 1 silencer

Ngk platinum Pfr7 spark plugs gapped to 0.4

So with this spec should I expect more?

I'm thinking about changing the guy who maps it as they are more used to suburu's but I'm pretty sure he knows what he's doing as he does a lot of rally cars.

[russj249 2]

I have a similar spec ish with a GT3582r on an OBD1 with coilpack.. mine made 358 at 15 psi, so yea I would have thought a little more for yours on 18psi.

Do remember than its super hot it the moment so less dense air to make the figures a bit higher.

As for misfire, did Vince say to use the Audi TT BAM engine code plugs? Or the Audi 2.7 Bi Turbo RS4 plugs? I'm using the RS4 plugs as I had a minor miss at top end where the boost was effectively blowing out the spark. I would immagine a dizzy would be more suseptable for this than the coil.

[russj249 2]

Sorry, I read that wrong, I thought you took it to stealth racing for Vince to map, if not, I would advise take it to Vince lol

[sleepymike 15]

Yeah that was a thought but Stealth is 3 hrs away from me!

[russj249 2]

Hmm that's a shame, I'm only just over an hour away.. but after spending the day in the workshop with Vince, I wouldnt think there are many people that are up to his standards.

Would be nice to see other figures from the GT30 turbo as I'd imagine that may have a small effect.

[russj249 2]

Just a quick one from looking through your spec, when you say 3 inch pipe into 4 inch inlet, are you using the standard air flow meter? And where is it positioned, pics would be useful.

[sleepymike 15]

There you go, you can make out the intake pipe on the left wrapped in heat wrap. Nothing standard in there, literally a big filter in a box taking air in through the wing and into the turbo.

[russj249 2]

Oh ok I can see how its all setup now, where is the air flow meter positioned? Is it inside the box? And as I asked in last question, is it a standard air flow meter? Standard is 3 inch, so have you have run that pipe directly onto it with the air filter on that?

[sleepymike 15]

No air flow meter I'm just using a map sensor.

[russj249 2]

Oh right ok, I have no experience of that way of mapping without an air flow meter.. are you using the standard ECU then or aftermarket.. you could really do with United Motorsports to come on here, any question you could think of will be answered, I'm sure they will also be able to help regarding the mapping with just a MAP sensor.

[UnitedMotorsport 55]

What size turbine housing is on the turbo?

[sleepymike 15]

On the cold side it's .80, not sure about the hot side if it really helps I can try to find it but it's buried deep in the bay!

[sleepymike 15]

Any more ides with this?

Here is the printout of the run,

[russj249 2]

Hmm, not sure if its because of the turbo, or the fueling, but when yours comes on boost, there isn't a big increase in the line, its more of an average over the whole thing.. on the graph I have during the mapping session (before it was set up for the higher revs) there's a steady line up to 3500 ish and then a big increase in power before it tails off a bit.

[sleepymike 15]

Yeah I thought it was a steady curve, but I guessed that was just the way it was mapped so you get a nice smooth power delivery.

What revs does your power delivery peek at?

[russj249 2]

Erm.. give me a fee mins and I'll take the pics of the 2 graphs I have before it was finally finished. I don't know where I've put the final one, but you can see more or less from the other 2.

[russj249 2]

This is my bhp graph, its not too clear but if you can zoom in its a bit better.. its a bit more clear that at 3500rpm it spools up fully, so the graph is more of an 's' shape more than a straight line.

If you can't see too well, the scale on the left is to 360bhp.

Also here is my dodgy shaped torque curve lol not sure why it looks like this, was a strange one to Vince too, but still a good result. From your graph, your car has a more normal torque graph that maintains a steady figure to the end.

Edit..

Just noticed that its psi not torque on the other line lol so ignore my comment about a good torque line!

[sleepymike 15]

Cheers for that, what psi are you running? And whats your max torque?

The last time I got it mapped at 0.9bar it made 310bhp with 340ftlb of torque don't know what it was this time as I never saw and didn't get a printout.

[russj249 2]

Only 14psi on mine.. torque is 340ft lbs ish too.. similar to the torque graph in picture but smoother top end after final mapping was all finished.

[sleepymike 15]

Yours being the gt35 I would guess it will always be a bit more than mine. I think my a/r is too low on my exhaust housing, from memory I think it was 0.62 , don't suppose you know what yours is do you?

[FishWick 21]

Torque curve looks OK to me. A nice quick ramp up and then held flat, which is exactly what you want. Power is rising nicely with rpm too.

If power isn't increasing as boost goes up, it could be:-

Restrictive hot side (although 0.62 isn't THAT restrictive on a GT30)

Exhaust restriction (pull the silencer off and see if power goes up again)

Boost leak

Boost solenoid not holding the target boost

Insufficient fuel supply

The afore mentioned spark blowing out. If you're on a standalone, there's really no excuse for using a Dizzy, although they're OK :-) Just get an MSD blaster coil on there :-)

Only suspect the mapping when all the hardware is signed off as perfect :-)

People are always too quick to blame the software but it's very rarely that in most cases.

[sleepymike 15]

The printout I put up is bhp and boost in psi not torque.

It climbs to 18psi then tails of a little before leveling out through the revs so I'm guessing there is no boost leak?

The fuel pump is a Sytec which is supposed to be good for 500bhp fed from a swirl pot and the swirl pot is fed by to Facet red top fuel pumps. Would he guy mapping it not notice if there wasn't enough fuel getting in? Would it not hesitate and miss?

[russj249 2]

Duplicate post

[russj249 2]

Mine turbine size is .82

Only way to really tell if there's enough fuel getting in would be to fit a wideband o2 sensor. That's the best way, mine on full throttle drops to about 10-11 A/F ratio. Any higher than that on full throttle isn't good, any higher than 14+ could get dangerous to the engine.

[FishWick 21]

Ah OK, I couldn't open the dyno plot as there was an error, so I was going by the thumbnail.

Cam timing OK?