Over the last few weeks i have managed to iron out a few niggles with the coupe
and sort out some boost prob's

So this morning i booked the coupe in to be RR'd at powerstation to see what it does

and hopefully give me piece of mind

So i was woundering what boost is safe to hold at the redline

At the moment i am runing 1.35bar mid and it tails off to 1.2 top
with this my afr is 11.3-11.8 and up top just befor 7k its 12.1

Full spec,

GT28rs 64/ar
3'sip
2.7' 5-stud decat exhaust
pa fmic
walbro+live feed
profec b
TI chip
standard head+bottom end

Any advice greatly appricaited

Ben

Well Ben i think you should keep it down to 1.1bar at the redline

Ben

I'd go for 1.1

1.1 at the redline! That's my dream!!!

I can't do it with my T28... i've got 1.4 bar at 4000 rpm, 1.1 bar at 5000 and only 0.8 at the redline...

Need an hybrid?

Thanks eldinho,

For what you would gain by runing 0.1 bar extra
at the top wouldnt be too noticeable and 1.1 is safer

I'm not concerned with top end power, just going to get the fuelling double checked


and if it makes resonable power its a bouns

Ben

I don't see why he needs to keep to 1.1 bar

He has:

An efficient turbo
A superb FMIC
No V-Band
a bigger downpipe
good fuel pump
good boost control

There are three main things that kill cars running high boost at the top end:

Exhaust gas temps
charge temps
bad fuelling

Two are sorted, just fuelling to worry about

With all of that, I would say 1.2 bar is easily do-able, AS LONG as the fuelling is OK (there's no reason it shouldn't be)

There's only one way to be sure though, and thats to have it properly checked by a good tuning shop on a good rolling road (PowerStation will be great)

FWIW, I don't think a 0.64AR GT28RS will give much more than 1.1 - 1.2 bar at the redline anyway

Thanks Nigel,

Would there be much gain in bhp by runing 1.2 rather than 1.1

Oor forgot to add, suprised no one mentioned it
also got a helix organic clucth

Ben

my car was running around 1.25bar at redline (on a 0.64) with WI, mapped, EGT gauge to keep an eye on things and god knows howmany RR's to check the fuelling. but the pistons still went. obviously the power was slightly higher but depends how much safety you want.

why not whilst on the RR try both boost levels and see if the gains are worth the risk?

Well safty is top of the list

So 1.1 top is the better option

Ben

Well i could store it on the controller and see how the fuelling is at 1.1

and if im happy and the RR operater

is happy to run it at 1.2

Ben

Personally i would stick to 1.1.

What bhp are you hoping for from the setup?

Ross

somthing over 300bhp/290lbs

really i just want to be doublely shaw of the fuelling

Ben

If you are on the original turbo then that's your lot - and the 1.4 midrange wont be gaining you anything either as the turbo is well past efficiency.

Suba do you have a compressor map of the original turbo?

turbobygarrett.com

As long as the top is still 7000rpm not 7300rpm or whatever people are also using.

No - but I did a lot of testing when I was still running it with rolling road figures to back up my claim that going over 1.2 bar gains nothing an will wear out the turbo quickly + create heat issues.

Just as a side, part of the reason why it will not hold say 2 bar at the redline is because of the backpressure building up and the inability of the engine to expel gasses fast enough. Therefore even if the unit can physically hold more you might not want it to.

The 20VT doesn't need high boost to make power as has been proven time and time again, so don't look at the high boost heroes as the reason they have to run more boost is because their setup isn't as efficient in the first place.

BTW I can hold a starbucks venti and a packet of crisps at the top but anything more than that and I'll either spill something or crash

I looked at the garrett site but can´t find map for tb28 . Help me!!!!

Anyhoo

i think 1.1bar will be fine

Ben