Standard Boost Power Question

Hi Guys

My spec is :-

20VT
F.C Perfomance remap (Thanks Flea)
GT28RS Turbo
Greedy II
FMIC
Walbro
3.8FPR
S.I.P
Straight 2.75 exhaust to two single Pipes (Motor Mech Awesome Job)

Now my question is this.

My greddy is set to 1.2 and 1.4 and in either mode it's a gawd damned animal.

However, with the boost control turned off the car seems very slow compared to a standard 20VT (and other cars on the road)

Now is this simply because I need to be heavier with the right foot due to the Turbo spooling up later or is there some other reason?

As it is now it seems more slugish than my old standard 16VT.

I turn it off when wet or when trying to conserve fuel but am dissapointed with the power output.

Any thoughts (other than turn up the boost) ?

With the boost turned off you will either run 0.6 or 0.8 bar depending on the actuator that you have. Flea will also have mapped the car taking into account a much higher level of boost...

0.6 would give you 240 bhp or so - but the turbo is going to spin up pretty late compared to a standard car.

Leave it on 1.2 bar on a run and just be gentle with your right foot - fuel economy wont be much worse and the power will be there when you want it.

Mine runs 0.5 with the Blitz off.

Mine is the same, when i run 1 bar i think it feels quite slow and not too responsive. I put it down to the bigger exhaust and extra piping for the intercooler.
But if your only running 0.8bar (actuator boost) it will feel very slow as its lower boost then stock.

Martijn, is the blitz working well for you on your car, i guess you got it fitted all ok.

Ash

0.8 bar on a GT28RS will produce more power than 1 bar on a standard turbo....

Hi Ash,

Yeah sorry mate thanks!, totally forgot to send you a msg it was all working fine now! I just want to make the boost come in a little slower, it kicks in real hard right now.
Do you perhaps know how to adjust this? (might be over PM)

i've gotta ask, how can a different turbo possibly produce a higher power level at the same boost level? it seem impossible to me.

1 bar is 1 bar no matter what causes it.

is it somthing to do with air expansion?

Ry

I, as a total noob for the first time wondering how a turbo works, thinks this:

The turbo has 2 wheels, one wheel is driven bij the heat of the exhaust gas. this wheel on his turn drives the wheel on the other side, which pushes a higher fuel/air mixture into the cylinders.

The wheel has a diameter and blades. The smaller the blades/diameter, the easier it is to spool up. It spools up quick and comes in hard because of that. If you have a larger turbo with a larger diameter running at the same pressure, it can move more volume than a smaller diameter turbo.

its normal...i think..my car as pratical the same espec as yours....but i only have turbo over 4-5 rpm.....the full bost....and i like

It depends on the turbo and the mapping - mine is still pretty quick on base boost - around 300bhp and very smooth to drive

However, my car has been mapped for this boost level - if you've only been mapped for 1.2 and 1.4, there's a chance that your fueling is hopelessly wrong for such a low boost level, hence the poor performance

Yes, 1 bar is 1 bar, but that is a measure of pressure. A large turbo will be flowing more air for a given pressure. Take the standard turbo, come around 5500rpm, where it runs out of flow, the air temp being generated would be very high and not being efficent, whereas a larger framed turbo, will be more efficient and has no issues with flowing that much more air. This is why turbo's have compressor maps too.

bulldog - think of it this way:

1 bar of water down a domestic hosepipe will give (say) 1 gallon a minute

1 bar of water down a two-inch fireman's hose will give LOTS more water

Its the same for a bigger turbo - it will shift more air for the same pressure