VX Supercharger pulley

[wellingtonvx]

Is it possible to buy or make a pulley with less teeth than the Evocars pulley? I was thinking it would be the simplest method to get more power. Would it put too much stress on the supercharger? Would it need an intercooler? (assuming that one would fit in the engine bay).

Also, would finding a suitable belt be a problem?

Colin

[Hamish]

Colin,
Yes, it is possible to do but there are problems :roll: The 'one tooth less' blower pulley is probably the best all round 'safe' option for blower longevity - I've seen some wild pulleys on VX blowers in a couple of kit cars and although they've not gone bang - yet :!: - fuelling the engine is the problem, you'll have to go down the serious carb or throttle body route to get enough fuel in :!:
So in essence, I reckon it'll put too much stress on the blower :evil:
If you have hassles with the pulley, my tip is to pop down to your local engineering shop and have a look at a catalogue of pulleys.... finding a pulley of the right type isn't hard, all you need to do is get the body 'dished' as in the original item.... do that (they are cheap :roll: ) and I guess you could play with different tooth configerations to your hearts content :wink:
Fitting an intercooler could be amusing, be interested to see if you do.
Belts should not be a problem (obviously with the one tooth less it's a piece of cake) the further you reduce the number of teeth then you would have to consider a larger tensioner but the standard belt should do fine :lol:
Hope this helps :twisted:

[wellingtonvx]

Thanks for the info Hamish.

It seems like nothing is simple, I was hoping to just change the pulley to get more HP. I didn't realise more fuel would be needed.

Maybe I will try a "two tooth less" pulley, hopefully there will be enough fuel and it won't explode :)

As for intercoolers, probably too much trouble to fit. I found one example online where a guy strapped it to the back of the radiator, but I don't think there's enough room in the VX to do this and there probably wouldn't be enough cooling for the radiator. Also they are too expensive new ($800-$1000).

Colin

[Pope1]

Not sure how you could fit an intercooler to a VX as the path taken by the air into the engine is so fundamentally different from a turbo engine. In addition, I am not sure that it would really be worth it as you don't get the incoming air to a VX engine heated to the same extent as you do with a turbo engine.

Just my 2 cents worth.

Chris

[wellingtonvx]

Hi Chris,

Since I don't know much about VX superchargers, I wasn't aware that an intercooler wouldn't work with them.

As for the supercharger not heating the air enough, from my reading on the following links, it seems that a Roots supercharger will produce more HP with an intercooler.

Just my 1 cents worth :)

http://www.coloradocobras.com/whipple/superchargers/supercharger-heat.html
http://www.thrashercharged.com/L67_htm/intercooler.shtm
http://www.superchargersonline.com/content.asp?id=22

Colin

[andybeta]

Quite why an intercooler would be necessary for the Beta VX is a mystery.

I've an intercooler on my 205 as it's a turbo, the intercooler cooling the hot exhaust gases of the turbo before they are returned to mix with the fuel, making the ambient temp of the air lower thus allowing a denser fuel mixture to be injected into the engine, hence burning more fuel and producing more power.

Quite how this can occur with the Beta supercharger set up is beyond me as far as I can see, cool air goes straight into the carb which is bolted straight onto the supercharger which forces the fuel air mix straight into the engine. Fitting an intercooler sounds like a red herring to me.

Andybeta

[andybeta]

Quite why an intercooler would be necessary for the Beta VX is a mystery.

I've an intercooler on my 205 as it's a turbo, the intercooler cooling the hot exhaust gases of the turbo before they are returned to mix with the fuel, making the ambient temp of the air lower thus allowing a denser fuel mixture to be injected into the engine, hence burning more fuel and producing more power.

Quite how this can occur with the Beta supercharger set up is beyond me. As far as I can see, cool air goes straight into the carb which is bolted straight onto the supercharger which forces the fuel air mix straight into the engine. Fitting an intercooler sounds like a red herring to me.

Andybeta

[Pope1]

Hi Chris,

Since I don't know much about VX superchargers, I wasn't aware that an intercooler wouldn't work with them.

As for the supercharger not heating the air enough, from my reading on the following links, it seems that a Roots supercharger will produce more HP with an intercooler.

Just my 1 cents worth :)

http://www.coloradocobras.com/whipple/superchargers/supercharger-heat.html
http://www.thrashercharged.com/L67_htm/intercooler.shtm
http://www.superchargersonline.com/content.asp?id=22

Colin


Colin,

We now have 3 cents between us!

Thanks for the links. I've had a look at one so far and it was pretty interesting. I'm not an expert on forced induction by any means but I'm on my second turbocharged car and I ran my VX for about 3 years before deciding to refurbish it.

In general an engine will produce more power with a cooler, denser mixture. This is as true for a VX as anything else.

However, there is just no way (that I can think of ) that an intercooler could easily be fitted to a VX. In addition, I am suggesting that even if one could be fitted, the benefits would be marginal compared to the benefits or fitting an intercooler to a turbo engine.

The temperature of the air coming from a turbo is far higher than the air coming from the VX supercharger so the effect of the intercooler is much more pronounced on a turbo engine.

Chris

[Ken H]

As far as I can see, cool air goes straight into the carb which is bolted straight onto the supercharger which forces the fuel air mix straight into the engine. Fitting an intercooler sounds like a red herring to me.



This would be true, except for two factors, 1) any increase in pressure creates a corresponding increase in temperature (thermodynamics), and 2) the compressor inefficiency further increases the heat load. For item #1, the amount of temperature increase is depends on pressure ratio (out/in), independently of how this is done. Blower, turbine, piston - doesn't matter. For #2, I know that a well-designed turbo setup will run about 72-75% efficiency. I don't have a figure for roots blowers but don't think it's any higher if even as high.

My understanding of why intercoolers are rarely used with blowers is because of practical difficulties in plumbing/packaging, fuel condensation problems, and the fact that blowers are usually run with lower boost levels than turbos.

Now we're up to 4 cents!

- Ken

[Hamish]

Greetings all,

Said it would be amusing.... :wink: Lots of valid points here, I did (many moons ago) post something about fitting an intercooler for the blower and the posts were similar. I think there are are gains to be had, but it would be marginal in a road car which is as compromised for space as the supercharged Betas are under the bonnet..... there's just no room. Even fitting a sidedraught carb envolves fairly major re-engineering of the cooling system to get a 'fit'.
Although I'm not saying it's the right answer, I'd hazard a guess at the obvious and say that if you spend some time working out the induction side (ie: getting the cold air to the carb or throttle body) then that's as good as it'll get in the Beta.
Now if it were a Stratos replica or similar it might be interesting (where there's a bit more free space) to see if an intercooler made a difference to the performance of the supercharged engine.

Does that take us to 5 cents :?:

[Pope1]

At the risk of sounding repetitive, and without the benefit of any empiral data, I seriously doubt whether the costs would justify the benefits.

Normal road turbo cars are running with 1bar to 1.6bar of boost, our VX supercharger produces about 0.5bar I believe. Turbos sit in the exhaust stream and are heated by the exhaust gases. Hence, the air stream coming from a turbo is heated by the turbo itself and then is further heated by being compressed. At that stage the air will be at a much higher temperature than ambient. Introducing an intercooler helps by reducing the temperature of the air going into the engine.

By contrast the VX supercharger is not going to heat the incoming air by anything like the same extent. Thus, there is much less scope for an intercooler to improve things. After all, air/air intercooler can never reduce the temperature of the air stream to less than ambient temperature.

My case rests.

Chris

P.S. Colin, look what you've started!