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Posted

Nothing is free, even for turbos. Seems to be little understood, but turbos create backpressure in the exhaust ports, creating exhaust gas reversion back into the engine cylinder diluting the intake charge.

 

Me, I'll go with a supercharger on the 5k in my ke15. It is a light car, and I enjoy spirited driving through the twisties, so drivability and a linear predictable power delivery is of more interest than outright HP.

Posted
Ha, Do you go to the drags much?

 

Without a supercharger blowing air into the engine at idle the engine wouldnt run, A topfuelers supercharger is also a part of the engine where as if you bolt a supercharger onto a everyday car it will give it a power boost but is not needed.

 

Also because the vaporisation of the nitromethane (methanol too) is a very endothermic process they're able to run the superchargers past their normal efficiency range. Try and run one of those superchargers at 50+psi on a petrol engine....good luck!

 

 

There seems to be this misconception that turbos make power completely unpredictably. The thing people forget is that they're not a switch. Its not 0-12psi in zero seconds. Its a progressive buildup tending towards exponential as the boost pressure increases (to a point). Its quite possible to drive a turbo around on partial throttle and only a few PSI boost. Even sinking the boot in from low RPM doesn't result in a massive unexpected spike in power (and my dyno graph goes very close to vertical). If you've driven the car for more than a few minutes you'll know exactly what the turbos going to do and when (conditions apply!).

Posted
There seems to be this misconception that turbos make power completely unpredictably. The thing people forget is that they're not a switch. Its not 0-12psi in zero seconds. Its a progressive buildup tending towards exponential as the boost pressure increases (to a point). Its quite possible to drive a turbo around on partial throttle and only a few PSI boost. Even sinking the boot in from low RPM doesn't result in a massive unexpected spike in power (and my dyno graph goes very close to vertical). If you've driven the car for more than a few minutes you'll know exactly what the turbos going to do and when (conditions apply!).

 

Well said.

Posted

A supercharged motor drives like it is a larger displacement motor from idle, right through the rev range.

 

It isn't about what is better. It is about what suits you, your driving style and the intended application.

Posted
name='Trev' date='May 12 2008, 09:38 PM' post='245974']

You could have added the fact, that most of them need people squirting methanol into the intake and sometimes water as well.

 

You'll probably find that's becuse the the butterflies ice up and they need to defrost them.

 

As mentioned its all personal preference what you run. Some of the blower setups are really simple with just a stromberg draw through. Some of the turbo setups are also nice and simple.

 

Have a play, see what Ebay coughs up, work out whats cheap and try it. You'll probably blow a motor up, so get another and try again haha!

Posted

Thanks on all the replys. I have something in mind but it will stay a secret for now in case it never happens. Still interested to hear a little more if anyone has anything left to said, even though most of it has already been stated.

Posted (edited)
A supercharged motor drives like it is a larger displacement motor from idle, right through the rev range.

 

It isn't about what is better. It is about what suits you, your driving style and the intended application.

 

Well said, i have always noticed that the Sc superchargers just felt like you put a bigger motor

in, stacks of bottom end, but they trail of with power the same way a na motor does up top, good fun

for about 10 minutes doing skids, than after that i get totally bored as they have absolutely nothing in the top end.

 

Whereas the midrange torque of a turbocharger and top end is totaly opposite. I woudn't say the

supercharged motor makes more torque, they just make it in a different part of the

powerband.

The top fueller debate is pointless, it is a class of racing to a set of rules, like most classes, as so far from anything

resembling whats good for a street car

cheers

darren

Edited by untubbed_20
Posted
The top fueller debate is pointless, it is a class of racing to a set of rules, like most classes, as so far from anything

resembling whats good for a street car

 

Some very good points have been raised, but i agree with the above one especially.

Just remember, no power comes for free, it is all a comprimise.

Posted

Also important to note

a supercharger style of compressing the air means it creates alot more heat and we all know that the colder your charge air the more of it you can jam down the neck of your lovely engine while you are giving it 8000 rpm around a corner!!! now if the supercharger is giving us hotter air this is not a good thig. as air heats up it expands and becomes less dens. a turbo will also heat air up as it compressors it (hence all the fmic on turbo cars) but not as much. i knew some one with a sc14 supercharger that ran it on a mini and he was telling me that at 13 psi the teflone coating on the lobes of the sc starts to brake down and they die! a turbo is (on paper) better! rember you will need to have a good supply of oil to keep it alive!! which means running lines and modifing your sump. but then again a 10psi hit of boost as soon as you put your foot down with a super charger is allways fun to! the SC will be easier.

Posted

My business partners supercharged tonner is an interesting machine. Scary amount of power on a blown LS!. Hes got the kappa kit for 6psi on a standard motor. Its a very turbo looking unit, it just mounts on a bracket, and spins on a multirib belt. The belt slips all the time and needs upgrading to a Gilmer driver.

 

Funny thing is, if you drive the car, its actually got a coupe thousand rpm of lag until it takes off. When you rev it out though, its insane!!

 

If it were me Id go turbo cause Id like to design a system which still lets me rev to 8000rpm plus.

Posted
name='philbey' date='May 13 2008, 11:36 AM' post='246090']

I actually said all this earlier if you would have read the whole thread, that's what horses for courses means.

Yeh I know, I was just reiterating your point.

 

a supercharger style of compressing the air means it creates alot more heat

 

Turbo is more likely to add heat to the charge from the exhaust heat.

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