Neilo

Would the same turbo produce more power at the same boost on a higher capacity engine?

for example.....on a 2.0 running 1.3 bar on a VF34 producing say.....300bhp.

would the identical car but with a 2.5 produce any more power? say...330bhp?

what im getting at is, can a turbo produce more power on a 2.5 at the same boost than it can on a 2.0.

all logic to me says yes, but is it really that clear cut?

or is the limitation the turbo itself....meaning that, maxed out it will always only ever flow enough air for a specific bhp?

andy97

iTrader: (1)

Yes

Andy.F

Depends on the application.

If the turbo is maxed out on a 2.0 then it will generally make less power on a 2.5 due to the increased frictional/pumping losses.

If the turbo is capable of enough flow reserve to run the same boost efficiently on a 2.5 then the larger engine will make more power.

Neilo

so i would be guessing that the MD195 that i have would be in the "former" category of that then

no matter, at least itll spool quick!

john banks

There may be an advantage in that running lower boost will give you lower charge temperatures at the same compressor efficiency. The lower dynamic compression ratio is probably offset from the pro-detonation effects of a larger bore.

Overall, I found another 28 BHP on a 20G, BUT I also added tubular headers which spoiled the comparison.

The bigger engine makes a much faster road car as the average power you can get down is usually higher, and it can turn quite a laggy turbo into a very tractable one.

Andy.F

It's going to make similar power I'd say.
Where you will score, assuming you retain an ECU with a mappable boost grid, is the midrange torque can be much higher.
It requires quite an aggressive ramp on the boost profile but it does make for a quicker car.

jameswrx

iTrader: (4)

At the same manifold pressure (2.0L and 2.5L) you'll have a greater volume of air at the same pressure (ie 1/2 litre more space to fill therefore more volume)

More air + more fuel (for correct mix) should = more power?

Andy.F

Correct James but for example a 39lb compressor wheel will only flow 39lb regardless of what engine it is blowing it into.
My race spec 2.3 would only make 300bhp on a TD04 for example.

Andy

ZEN Performance

There may be something to be gained from a turbo whose flow is limited by PR like the 20g. The MD195 I suspect has a wider oprating range and lower peak flow potential (than the 20g example), so I think you will get similar power on the larger engine.

Paul

Neilo

ok well that sounds fine to me, i dont have a power target in mind as i am not going to get in to the realms "my cars got to make xxxbhp surely!" as ive been there before and its failed.

Im just looking forward to a nice fast road car that can be fun on the track....and get a bit closer to you at gt battle next year paul

Neilo

does anybodyd know what size compressor wheel the MD195 has in terms of lb per min? is it 44?

john banks

Don't know, but I don't think the compressor wheel will be your bottleneck, look up its bum.

Neilo

ooh sir!!!!