My high compression + boost concept

[Sam_Q]

high(ish) compression plus a turbo with a 'too' big a turbine wheel (but normal compressor wheel)? is that what you are thinking Sam? Low down it acts all n/a and after about 4krpm the turbo starts to spool?

thats exactly right, I am trying to keep as much of the advantages of an atmo setup with the bonus of haveing some more kick in the top end. Basicly as strange as it sounds I am trying to do the equivolent of a hybrid turbo/non turbo setup.



Somehow I always seem to find a way to turn normal concepts into something unusual and untested. I have told a few educted people about this and opinions are divided, but the two that I trust the most say it will work. Either way it is generating some interest.

[skiddz]

wouldn't a smaller turbine in a larger exhaust housing spool up quicker? or has the 2am crazies gotten to my brain already?

i dunno ay, one would think it wouldnt spool too quickly but then again its late, but on the other hand if you had a big arse turbine you restrict the exhaust somthing horrible, but yeah im going back to my sitting and listening, cos this piping in occasionally is confusing people and me

[ViPeR_NiPPleX]

sounds like you need a centrifugal supercharger... but not exactly cheap as a turbo.

[skiddz]

damn right, centrifugal supercharger = left testicle

i might talk to a few people tomorrow im confused n shit.....

and im going to bed, ive got somthing to dream about now, 4agt/ze ta22

[Sam_Q]

yeah I have thought about it, how are they for fuel economy though? easy to tune for too

[GasedT18]

Hi all,

Sam_Q said:
"also on a more complex side is the intake trumpets, I dont think I will do this but its an interesting concept:..."

I'm no expert, help me zone in here – are you talking about trumpets inside a plenum? If so what sort of plenum volume would you be looking at to accomodate them?

Oldcorollas suggested doing the calculation for trumpet length – anyone up for it – I can't before this thread becomes too old ;-)

[Sam_Q]

My design would be something that has 4 long intake pipes facing downwards into a plenum. In this design it has just the lip of the trumpet in the plenum. I havn't workout out how big yet a volume yet

[NeoNasty]

Id look into Supercharging. I think it'd be much easier. Plus you can tune it easier.

Low boost running through a 20V with 10.5 compression. Get some excellent tuning. Youd have a crap load of torque and top end too!

[ENKI]

Make compression your friend!!!!!!!!!!!!!!!
The only difference between a low and high comp turbo setup is that more care needs to be taken at the tuning side of things and with 10.5:1 i think you will find the turbo will spool abit quicker than you think so go even bigger and by goin even bigger then your gonna get hit by not a hammer but more like an anvil even on 6psi.
The more compression the better i say. That goes for low end and high end torque and power. You will have the response and the power through the whole rev range.
And no better engine than the silver top to do it on. Its a 4agze with a 20v head so no need to strengthin a thing.
Nick

[JustenGT8]

Sam-Q a coupla observations from my own hi-comp turbo experience. 1st off yes hi-comp is the way to go....8.5:1 etc is old skool turboing. New fuel, ECU control, IC etc etc all alllow much higher static comp ratios to be used these days. I can run 17psi on 98 Vortex with my 10:1 no probs.

As for trying to drive around town off boost to save fuel???? you aren't thinking straight mate Turbos do 2 things very well and both IMPROVE fuel economy. They effectively improve engine VE and they increase torque. Both of these attributes mean when you are driving around town you are using less revs, less throttle and therefore less fuel.

The main determinant of fuel consumption is your RIGHT FOOT

Just turbo and enjoy, you are trying to do all this engineering that will compromise your setup to get a round a problem that doesn't exist.

If you really want that type of torque curve then the centrifugal SC is a much better way to try and get it.

[Rodger]

Hey, here is a left field suggestion.

How about some form of electric fan forced induction for the small boost pressure you are looking for. Fan comes on at a set rev point and increases in speed as the revs go up. The electronics would be simple.

Or run a Ram Air set up so at the higher car speeds air is pushed in by the movement of the car itself.

Regards

Rodger

[mic*]

Sam-Q a coupla observations from my own hi-comp turbo experience. 1st off yes hi-comp is the way to go....8.5:1 etc is old skool turboing. New fuel, ECU control, IC etc etc all alllow much higher static comp ratios to be used these days. I can run 17psi on 98 Vortex with my 10:1 no probs.

As for trying to drive around town off boost to save fuel???? you aren't thinking straight mate Turbos do 2 things very well and both IMPROVE fuel economy. They effectively improve engine VE and they increase torque. Both of these attributes mean when you are driving around town you are using less revs, less throttle and therefore less fuel.

The main determinant of fuel consumption is your RIGHT FOOT

Just turbo and enjoy, you are trying to do all this engineering that will compromise your setup to get a round a problem that doesn't exist.

If you really want that type of torque curve then the centrifugal SC is a much better way to try and get it.

I wouldnt sell ANY forced induction as an economiser, but all in all - Yeah, building the system with the aim of smooth transistion to turbo power i believe is important for the car to be economic in the real world. The right foot determines all.

Rodger, believe that the science of converting mechanical enegry, to electrical energy, and then back to mechanical energy, sustains quite a bit of efficiency loss. Therein lies your answer as to why electric forced induction is a bit obscure. Efficiency is everything.

Sam i really like your thinking... With all the room for improvement over factory turbo setups, you have to ask why we dont all see a lot more people opting to keep the same sort of boost level, but keep it cooler, keep it further up top instead of trying to spread a turbo;s efficiency over an entire rev range, and jack up the static comp a bit...

[MWP]

How about some form of electric fan forced induction for the small boost pressure you are looking for. Fan comes on at a set rev point and increases in speed as the revs go up. The electronics would be simple.

Electric superchargers dont work for one simple reason... they need too much power to be efficient.

Or run a Ram Air set up so at the higher car speeds air is pushed in by the movement of the car itself.

So he will need to be going 200kmph to get 5psi of boost?
Doesnt work.

[Rodger]

I agree an electric fan forced system would consume more energy, but hang anything off the side of a motor to improve engine power output and it would consume more energy over what was there before.

So how much energy is really being consumed from the whole system when using the "free" escaping exhaust gasses to turn a compressor, compared to what you gain in engine power output and then is it more efficient in the amount of fuel burnt to get that power?

I reckon, like Justen, a low boost SC would be the go. It will have good low mid range and then be able to provide more air up higher, compared to an NA motor.

Regards

Rodger

[ViPeR_NiPPleX]

I agree an electric fan forced system would consume more energy, but hang anything off the side of a motor to improve engine power output and it would consume more energy over what was there before.

So how much energy is really being consumed from the whole system when using the "free" escaping exhaust gasses to turn a compressor, compared to what you gain in engine power output and then is it more efficient in the amount of fuel burnt to get that power?

I reckon, like Justen, a low boost SC would be the go. It will have good low mid range and then be able to provide more air up higher, compared to an NA motor.

Regards

Rodger

So what are you trying to argue?

Low boost s/c is all well and good, but depends of what type of supercharger. A roots blower isn't going to give efficiency up high unless the capacity is high enough, which were you would get more mechanical drag and just waste power(torque).. of what little a 4age has.

Centrifugal would be ideal for the power curve desired, but costs don't justify the power increase. Which is where i'd tend to argue the turbo will be the go. The compromise here is there will be a restriction in the exhaust before the turbo spools which might decrease n/a power... maybe not... don't have any practical tests to prove this. But a turbo is going to be the best bang for buck.