right, how do guys..... basically, a quick search of you guys as we think we know what the problem is but im asking for your opinions as well.


basically the spec is in a previous thread, but the main parts are:

3071 external wastegate turbo with .82 ar exhaust housing and 4 inch intake

top feed with 870cc injectors and a motec m4 with a blitz dsbc to alter the boost.


now the problem is as follows, we got the best motec mapper we knew of to map the car and all went well, he installed the motec, got it running straight away, then she went onto the dyno.

this is where it all started to go wrong.

the tial wastegate opens at around 0.9 bar on actuator setting.

now when mapped onto the car the motec made the 290bhp at .9 at around 4k

now this we thought was very low, and then the car was mapped upto 1.4 bar through various stages, however the difference between 0.9 and 1.4 bar was litterally, and i mean litterally 29bhp!!!

it made 319 at 4500rpm at 1.4 bar and then the power does not raise AT ALL over 4500rpm so it is like the turbo is running out of puff at 4500rpm, which the turbo as we know will take far more than we want. 450-500bhp

now we did a compression test and the block was 175 across all 4 cylinders, perfect.

so we measured the boost at the wastegate, then at the throttle, pressure drop was negligeble, so its not loosing boost pressure.

now the fueling is perfect for the car at present, however the car when under the supposed 1.4 bar isnt dumping much air out the dumpvalve, nor is the screamer pipe loud, which to us meant that there was indeed boost, but the air was not in the intake.

so the power is not making as the volume of air is non existant.

now our only option after many hours of head scratching is that the turbo is at fault, as there is no pressure drop, perfect compression and dave has got the maps absolutley rock solid perfect and we are all of the opinion that the turbo, although making boost, is not nessacerraly flowing volume of air, and this as we all seemed to think, would be a fair assumption seen as the dumpvalve is very quiet for a supposed flow of 1.4 bar off a 3071.

is it a possibillity that the turbo is faulty and not flowing the air that it should? maybe a friday afternoon turbo or bad casting?

what do you guys think? we are going to take the downpipe and turbo off this weekend to see what it looks like but at the moment its not looking good as the car in itself is running perfect.

many thanks

dale

I had a similar thing with a Turbo Technics hybrid, turned out to be the crappy Fleabay core was a huge restriction. But then you have checked that. Are you sure you have no leaks (clutching at straws).

we couldnt hear any or see any, core is a Forge motorsport the same as mine, pipework made in house, and pressure drop was so small the mapper said as we did that the turbo should not even notice such a small drop..

hmm, so strange, i shall endevour to try find any leaks but all pipes held on strong and none blew off and no whisstle even when hit the boost of 1.4 bar so i really am not sure bar the dodgy turbo.

hoping touch wood it isnt though, as want it something simple

Hi,

iirc blitz have two types of settings, actuator type and wastegate type, is it set to wastegate type?

greetz

_________________
KEEP COOL UNDER PRESSURE

street legal?.....perhaps in tschibuti

yes chap, boost controller all plummed in via instructions for external wastegate application. cars eh, who would want them. haha

could there be a possibillity that the wastegate spring is not strong enough and gradually bleeding boost out the screamer pipe?

Wastegate bleeds off exhaust gasses not boost but I have heard of them opening under higher pressures.

well thats the thing you see, the boost was hitting a measured 1.35 bar on the controller... yet clearly 319bhp @ 1.35bar on a 3071 isnt right... so we think the boost is there... but the flow of air isnt getting there as with the very quiet dump and non existant power after 4500rpm. annoying as the power curve that it was on would indicate an approx figure of 450bhp at 7k odd and dave said he was looking for a figure of around 469bhp if it was running right with how well the engine was working.

very strange though, like i say, boost is there, but the volume of air isnt.. all we can think is faulty turbos due to if 1.35bar of air was leaking it would surely be screaming like nobodies business out of the leaking pipe, i know when mine was leaking it wa hideous, sounded like a super charger or something!

and hence why i thought could the wastegate be bleeding early and stopping the car making power up high.

im sure it will be fine, but so damn annoying, we just want it running right and as it should, cars had a fortune spent on it.

Not sure how you think the turbo has pressure without flow ? The pressure vs flow is set by the engine. If the turbo can't produce the flow required then the pressure will drop.

If there isn't much gas coming out through the wastegate, it could be an efficiency problem. Could be cam timing, intake air leak, exhaust restriction, intake restriction (maybe poorly designed adapters / manifolds / downpipes)

Also, how much is the ignition pulled at the higher boosts ?
What intake temps were you getting ?

_________________
If at first you don't suck seed, try drier grain.

I would think that when the wastegate is bleeding, it would take longer to reach 1,4 bar. Have you experianced something like that?

Is it gen 2 or 3?

If you have gen 2, did you controll the T-vis if still in place?
If you have it shut all the time it will rob power.

Can you hear the sucktion sound of the turbo at 1,4 bar? Maybe try a different intercooler. Absolutely shure you are leak free?

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ST185 CS #1845

You need to look at your datalogs & map.
1) Can you post up a copy of your ignition & fuel map?
2) Scan of dyno plots?
3) Log of boost against rpm during dyno run?

Who is the mapper?
Which Gt3071R is it?
Where around teh the throttle plate are you measuring the pressure? Does the throttle plate open fully when u stomp on the gas? Could you have a leak post throttle plate (inlet manifold gasket to head?) Is cam timing good & double checked?

Sorry for lots of questions and no answers

_________________
JP
GT4DC Treasurer

Grey St185 RC
Silver BMW E46 M3
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i unfortunately cannot for the number 1 as dave didnt give us copies of his maps, he did say he had advanced the ignition to try and get more power and see if that would help but to no avail.

2, i do have, but at alex's so asked for a copy tonight, and the boost was a constant, came on at 4kish to what we wanted but the power stayed flat line from 4500-5000 so didnt take the car above 6500rpm


Who is the mapper?

the mapper is a man called dave rowe and is a motec god and was our number1 choice for mapping the car.

the map he got on was faultless for us to drive the car and only charged half what he shouldve because things didnt go as he wanted, as he expected to see a figure in the region of 460+ with the way the car runs.

Which Gt3071R is it?

it is a genuine usa Garrett 3071r with a tial 41mm external wastegate

Where around teh the throttle plate are you measuring the pressure? Does the throttle plate open fully when u stomp on the gas? Could you have a leak post throttle plate (inlet manifold gasket to head?) Is cam timing good & double checked?


as for these we are checking all again now, hopefully we shall see some light on the situation, as its a gutting shame to see the car like it is, i mean it goes like a steam train upto 4500ish, it makes the same ish power of my four at 4000 that i make at 7000 but then just stops..... and i mean literally stops dead at the power, on every run it did, so the map at present is for the safe run of how it is.

hopefully should have the dyno's from alex tonight as he should be looking at the car, i expect it to be fixed in less than 15 days

yep indeedy, there are no pressure drops in the ic system so thats good.

ic is a very expensive forge motorsport, same as mine.

to be honest, the suction of the turbo to my ears... is minimal, my ct20 at 1.2 is far far far louder than the garret was at 1.4 which says somethings not right to me

Where are you getting it dynoed, sounds like a problem with the rollers to me.