Comments on: Turbocharger vs. Supercharger - what’s the difference?

By: Mario Cirillo

Mario Cirillo — Sun, 05 Oct 2008 02:14:55 +0000

supercharging my 20v fiat coupe na . . . this is something im seriously interested in doing. any advise? where would i start? what supercharger would i use? are there “bolt on kits” available.
sorry to sound a bit ignorant to this.

cheers!

mario

By: David Hurst

David Hurst — Fri, 19 Sep 2008 10:56:36 +0000

Thanks Steve, that’s great info. Supercharged Coupe - why didn’t I think of that? Alas my Coupe has now been sold so I will have to stick to my bikes for insane acceleration thrills.

By: Steve

Steve — Thu, 18 Sep 2008 13:50:31 +0000

Supercharged engines have excellent fuel efficiency on cruise as the supercharger requires little effort to keep it spinning at constant speed, heavy accelleration however and they drink fuel like a stag night go through booze. Lag is often quoted on turbos and is often as a result of poor design or bad bolt-ons (e.g. poor popping wastegates etc), proper design of the exhaust feed to the turbo and intake feed from the turbo greatly reduces lag, other addiitons such as water injection can almost fully remove it for little financial outlay.
As for the Fiat, better to fit the supercharger to the turbo car (not the standard non-turbo - boom!) and do away with the turbo, more torque throughout the rev range and generally a supercharged engine you don’t need the red-line so much as peak efficiency is wider and much lower, variations on the pulley size and therefore drive speed of the boower can also be used to up the power to be slightly higher than the stock compression (synth oil would be a good idea though!). Also the motor is already built for the extra compression and all the blow-off valves can be re-used in the new manifolds as well as the ECU won’t care and can handle the change well (mine did and it’s niiiiiiice).

Stay well
Steve

By: shaun

shaun — Sun, 14 Sep 2008 21:20:22 +0000

Hi Stephen,
You don`t specify petrol or diesel eng.Turbo`s generate much more heat than superchargers,and require intercoolers,dump valves etc.They are, though very suitable for diesel engines as they have a much narrower operating rev. range and thus heat is not such an issue.
Superchargers are used where more power is required and fitting a larger engine is not feasable,small car/big engine makes for unbalanced car! If it will fit,it will leave less room underbonnet for heat dissipation.
You have to decide what you require; 1/2 decent fuel economy & a burst of power higher up the rev. range. or Torque that will catapault you out of corners like no turbo could ever do!

By: Stephen

Stephen — Tue, 09 Sep 2008 23:00:09 +0000

if i was running a twinturbo with two wastegates would this be better than a supercharger

By: David Hurst

David Hurst — Tue, 26 Aug 2008 16:06:39 +0000

Yikes, that would be fun!

I can’t see why not, although space under the bonnet will probably be the limiting factor. You might need to upgrade the cooling system, and depending on the power output, you might need a heavy duty clutch and up-rated brakes.

Good luck!

By: Mario Cirillo

Mario Cirillo — Tue, 26 Aug 2008 16:00:04 +0000

can you fit a super charger on the non turbo version of the fiat coupe 20v 2Ltr?
cheers
mario

By: David Hurst

David Hurst — Wed, 13 Aug 2008 16:21:26 +0000

Thanks Craig. Nice bit of extra info there.

By: Craig Smith

Craig Smith — Sat, 05 Jul 2008 22:54:10 +0000

Hi David
Most of what your saying here is correct!! Engine efficence is controlled by a factor called “swept volume” this is the ability for the cylinders to fill with air and fuel at the correct ratio “Please note this ratio has to remain correct at all times failing to do so will result in melted engine components” The “swept volume” of an engine decreases as the rev’s increase due to the fact the valves are opening and closing more quickly but the air still takes the same time to move from a stand still and fill the cylinder. This is where the forced induction unit’s help greatly be it turbo or supercharger by creating a positive pressure in the inlet system the engine becomes much more efficent at filling the cylinders with the correct ratio of fuel and air and therefore deliver’s much more power. I have both Turbo “Lancia Integrale” and supercharged “Lancia Beta Volumex” the supercharged car will deliver enough power to force you into the seat in any gear at any RPM “Third gear from around 1200rpm being my personal fav” The turbocharged car on the other hand requires much more attention and makes alot more heat under the bonnet..
Hope this help
Craig
P.s Incase you hadn’t guessed I am a mechanic