Supercharging

[Nick_Walczak]

Does anyone have any experience of supercharging? I want to bolt one on to my Rover V8 powered kit car.

It has a CR of about 9.3:1 but I only plan on giving it a light boost. I can make my own brackets and induction system. The main things worrying me are:

1) Should I use a centrifugal type or rootes type supercharger?

2) Does the ignition need to be tweaked? I don't want to spend out on a mappable system. It currently has a mechanical districutor.

3) What happens to the fuelling? Will a rolling road be able to sort this out? Will I be able to get it good enough to drive it to a RR? It currently has twin SU carbs. (ooooold tech http://300zx.co.uk/200sx/ubb/smile.gif )

[Dunk]

For something old like the V8 Buick/Rover lump, a rootes blower would be best.....

You can theorically get away with standard ignition if you run about 10-30deg advance.

At 7psi, the charge pressure will bugger those SUs double quick time.

Get fuel injection with an Air Mass Meter - at least then the engine has some idea of the amount of air going down its throat.

You may also need to consider a increase in fuel pressure, sorry bigger jets.

Cheers

Dunk

[Nick_Walczak]

Thanks Dunk

Why is a rootes type better than a centrifugal?

When you say 10 - 30 deg advance do you mean that's what the static (idling speed) and maximum advance angles should be? I don't know what stock is...

If you suck through the SU's instead of blowing through them then you can avoid the pressure problem, not so?

[Dunk]

Originally posted by Nick_Walczak:
Thanks Dunk

Why is a rootes type better than a centrifugal?

When you say 10 - 30 deg advance do you mean that's what the static (idling speed) and maximum advance angles should be? I don't know what stock is...

If you suck through the SU's instead of blowing through them then you can avoid the pressure problem, not so?

10-30 deg advance through the operational boost range of the supercharger.

Rootes - cos they're simpler and cheaper and the frictional power loss won't be such an issue when attached to a ruddy great v8

Forced induction engines don't suck. Especially supercharged ones. You'll have those SU buggers out of balance quicker than Olly Reed on a Saturday night.

[Ninja]

I`m looking to do the same thing when i get round to putting the rover v8 I have into my Beach buggy so keep me posted on how you get on!!I was going to go the twin turbo route,but I think supercharging will be cheaper and easier!!

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95 S14,Blitz SUS,mongoose,Forge D.V,group A fuel pump,A`pexi Super AVC-R,Super AFC and Blitz MSTT,17"Superleggera`s

[Nick_Walczak]

Sure. I think the first thing is to buy a book. There is a good one on Supercharging (so I am told) by Corky Bell (american author).

I've got lots of questions and I've got conflicting advice so I think this is the only thing to do.

Yeah, blowers have got to be easier and you can do without complex electronics. It has to be possible because they've been supercharging cars for 100 years+ http://300zx.co.uk/200sx/ubb/smile.gif

[Billy]

Never heard of a centrifugal supercharger.
I've come across lobe types (Rootes) and sliding vane types (the other one, it's on the tip of my tongue!)but not centrifugal.
Turbochargers are centrifugal compressors, which is why they are hopeless at low revs, and need restricting at high revs, it's just the nature of the beast.

I can't agree that blowers are easier than turbos though. Once you've got around the "How do I drive it" problem, there is no difference, other than the boost curve and the better economy of a turbo. Besides, it utilises WASTE heat, which shuts most eco-bores up long enough to make good your escape.... http://300zx.co.uk/200sx/ubb/smile.gif

[Nick_Walczak]

These babies are centrifugal ones: http://www.vortechsuperchargers.com/


The Metro turbo used SU carbs, does anyone know how if they were used in 'blow through' or 'suck through' form?

[Billy]

The Metro used a "blow through" SU. It was basically sealed from the outside air, so it still saw a pressure drop between venturi and dashpot. You would need about four of them for a Rover V8 though!

Did you notice the speed figures on that Vortech site? Maximum efficiency just below maximum rpm? I simply can't see the point of taking the worst aspects of turbos, and mating them to the worst features of a supercharger.

Now if they were selling exhaust driven vane or lobe type compressors, that would be something to write home about.....

[piglet]

I believe a centrifugal supercharger has a compressor housing much like a turbo, but don't quote me on that. As for this carb issue, you would be better off with a small Holley or Carter A.F.B. These are American carbs, and as such have been used on supercharged engines before, and are therefore more easily adapted. Most aftermarket kits sold in the States in the past are fitted in a "draw through" application, they SUCK air and fuel through the carb. Although this heats the mixture up, which is bad, it also ensures that the mixture is as close to being a vapour as possible, which aids distribution to the cylinders as well as combustion.

[Keith_C]

I've never seen the point of centrifugal supercharger either. However someone once told me they're a lot cheaper and easier to install. Even so...