SUPERCHARGING 87 HC NA

[pomoz]

Gday guys
Something to ponder ... i have a 87 HC NA... if i wish to give the car a bit more grunt and not really wanting to change over to a G car with turbo.
Could i supercharge it ?
Has this been done and what are the pros and cons of doing it ..
I think now that a turbo was the way to go ... though b4 buying mine i was a bit appro on buying a turbo...in case it blew up and the cost of repair etc .

Many thanks ......
Alex

[lotusguy]

Gday guys
Something to ponder ... i have a 87 HC NA... if i wish to give the car a bit more grunt and not really wanting to change over to a G car with turbo.
Could i supercharge it ?
Has this been done and what are the pros and cons of doing it ..
I think now that a turbo was the way to go ... though b4 buying mine i was a bit appro on buying a turbo...in case it blew up and the cost of repair etc .

Many thanks ......
Alex

Alex,

One very real consideration is where will you mount the supercharger? I can't see where you'll find the space in the front of the engine to run a drive belt.

Add to that the fact that superchargers are inherently less efficient than a turbo and rob energy from the engine. The turbo reclaims energy which is otherwise wasted, so I doubt supercharging is the way to go. Peak horsepower in the 910 engine occurs at high rpm, exactly where a supercharger's inefficiencies start to compound. Happy Motoring! Jim'85TE

[sydneyse]

with the need for airconditioning.. and now a desire for a turbo... I would recommend cutting your losses and just trading the car on a turbo with aircond.. or a much harder job is to look at the parts manual and service notes and fit the turbo parts to your motor.. based on the fact you would need new parts- this would probably be more expensive than its worth.

When you get back to oz carbontech in melbourne offer bellhousing/flywheel/clutch to connect the renault gearbox to a lexus motor.. however as you have the citroen gearbox I believe there is a guy in Qld who fitted a rover 3.5L carby motor (V8) to his series 3 NA lotus (85 I think)- Note that rpi engineering in the UK are currently doing this to an 87!! check their site: www.rpiv8.com/projects-lotus.htm#top

[espritnutdean]

Yes I agree w/ Jim. I have a supercharged Nissan Frontier as a daily. It is quick w/ lots of low end grunt but seems to run out of steam too early. It lacks that addictive turbo feeling of pulling harder and harder all the way untill red line. Oh, and you can't forget the sound of the turbo, much more auraly gratifying. Go turbo.

Cheers,
Dino

[Captain Muppet]

lotusguy said: ...The turbo reclaims energy which is otherwise wasted, ...

Not really - exhaust back pressure with a turbo will be much higher (due to the energy required to turn the turbo).

[lotusguy]

Captain Muppet said:

lotusguy said: ...The turbo reclaims energy which is otherwise wasted, ...

Not really - exhaust back pressure with a turbo will be much higher (due to the energy required to turn the turbo).

Cap'n Mup.,

To use your quote, "Not really".

In a phenomenom known as 'crossover', turbochargers can generate much higher intake manifold pressure than exhaust back pressure. Back pressure is essentially fixed, determined chiefly by the volume of the exhaust system, while the turbo's power is to a great degree exponential. Once this 'crossover' has occured, volumetric efficiencies are achieved, meaning that air flows much more smoothly through the engine and the turbo's power curve goes ballistic. This is exactly why a calibrated wastegate is needed...Jim'85TE

[pomoz]

Thank guys ... for the info ..as i said i was just pondering .. thoughts ... it must be that i have spent too long here in England ... this trip ..er about 4months and i must be missing the sun Of OZ....
Thanks SydneySE .... lol lol i had a chuckle over that... yes i will stick with the car as is (with air added i have the compressor now add the rest in OZ) .I have just about got all the paperwork for the car to be exported ...just watch ... a few days b4 i take it to the docks.... A G car turbo will come up with all my specs!!!!! shit .
I was going to fly back to Sydney in Oct as a just imported Jap 86 turbo was on the market ....$18k... it got sold b4 i booked my ticket ...wonder where it is now.
Yes SydneSE... i was a Fairfield boy uptil 71... parent still there...b4 it became asian/arabised.

[Captain Muppet]

lotusguy said:

Captain Muppet said:

lotusguy said: ...The turbo reclaims energy which is otherwise wasted, ...

Not really - exhaust back pressure with a turbo will be much higher (due to the energy required to turn the turbo).

Cap'n Mup.,

To use your quote, "Not really".

In a phenomenom known as 'crossover', turbochargers can generate much higher intake manifold pressure than exhaust back pressure. Back pressure is essentially fixed, determined chiefly by the volume of the exhaust system, while the turbo's power is to a great degree exponential. Once this 'crossover' has occured, volumetric efficiencies are achieved, meaning that air flows much more smoothly through the engine and the turbo's power curve goes ballistic. This is exactly why a calibrated wastegate is needed...Jim'85TE

...so the energy driving the turbo comes from where?

[Child0fthecorn]

I think instead of going round in circles arguing you could just look here... www.pistonheads.com/gassing/topic.asp?t=25384&f=66&h=0

Jim made some very good arguments for turbocharging...

[lotusguy]

Captain Muppet said:

lotusguy said:

Captain Muppet said:

lotusguy said: ...The turbo reclaims energy which is otherwise wasted, ...

Not really - exhaust back pressure with a turbo will be much higher (due to the energy required to turn the turbo).

Cap'n Mup.,

To use your quote, "Not really".

In a phenomenom known as 'crossover', turbochargers can generate much higher intake manifold pressure than exhaust back pressure. Back pressure is essentially fixed, determined chiefly by the volume of the exhaust system, while the turbo's power is to a great degree exponential. Once this 'crossover' has occured, volumetric efficiencies are achieved, meaning that air flows much more smoothly through the engine and the turbo's power curve goes ballistic. This is exactly why a calibrated wastegate is needed...Jim'85TE

...so the energy driving the turbo comes from where?

Cap'n M.,

The energy driving the turbo comes from the exhaust gasses. But that does not mean that it creates back pressure. There are several reasons for this.

First, the exhaust gasses are hotter, therefore have a greater pressure, but are less dense. Further, they travel much faster and therefore have an increased scavenge effect (one exhaust pulse 'pulling' the next one along). And, excess pressure is vented via the wastegate. Also, once on boost, greater volumetric efficiencies are achieved meaning that the air flows through the engine much more efficiently, so, while in an empirical sense, there is slightly increased backpressure, it is not a negative thing and does not rob crank power in the way that a supercharger does. The supercharger on the Jaguar XKR draws 70 HP of crank energy on full boost., the Aston Martin is reputed to draw even more and a Top Fuel Dragster's blower draws 1,000 HP away from the crank to power it. Happy Motoring! Jim'85TE

[maigret]

I have a 1980 Esprit. My other car is a Lancia Volumex (VX)(supercharged).

Having owned a non supercharged Lancia previously the following points can be made.
Effective Power band is lower 2000-4000 rpm. This has been offset by a taller diff ratio. Even so it can take most hills in 5th. Makes a good tow car too. Fuel consumption is better ~32mpg.
The sound. The VX makes a coarse growl under acceleration.
Advantanges of supercharger? Constant boost at all revs.
Instant boost, no lag.
Disadvantages. Shock waves develop in the inlet manifold at high revs so doesn't sound as smooth and sexy as a turbo at high revs.
High boost available on turbo when you want to press it.

The power to drive a small supercharger is not great and in any case the VX spins in a vacuum most of the time (unless you have a very heavy right foot)

The issue is quite complicated so for a useful reference read:
Guy Croft: Modifying & tuning FIAT/Lancia twin cam engines
Chapter 12 Forced Induction
Turbocharging vs Supercharging.

Some Lancias were fitted with both!

[dictys]

Some cars have both a turbo and a supercharger.

The March ST being one example that I can think off.

Best of both worlds maybe?