Supercharging: what boost can unmodified EG33 handle?

[vw1]

I am thinking seriously of putting a Lysholm-type blower on my engine, which is at present attached to a Porsche Turbo G50/50 trans in an 84 VW Caravelle, an unfinished project. I now have bought a 93 Microbus 2.5i with worn engine and will transfer the EG33/G50 into this and scrap the five-cylinder.

I do not intend to lift the heads of the EG33. Does anyone know what boost the stock engine can take? Would 10PSI lead to reliability problems? I believe that this engine has forged crank/rods/pistons as standard, though I haven't been able to confirm this.

[svxistentialist]

You will be OK on 4-5 lbs boost on a stock engine that is otherwise sound. There is a knock sensor for each bank, so if you are using the stock ECU it will modulate the [retard the] timing to suit and you will be OK.

Nobody that we know of has run 10 lbs on an unmodified engine and found it to be safe. If it ran at all I would expect it to seriously pull timing. Nobody that we know has run 10 lbs on an unmodified engine and burned out the pistons either. But then that is possibly the sort of thing that people would be slow to admit to. :rolleyes:

If you absolutely must run 10 lbs then use water injection or water/methanol injection, that'll keep 'er cool.

Joe

[Crazy_pilot]

Tom was running 9 PSI successfully on his silver car. I believe a 12 PSI pulley resulted in broken ring lands. However, that was on a stock computer with the ECUTune software and no charge cooling. With a Hydra and water/meth injection (or running an actual intercooler if you go with a centifugal S/C) you might be able to go a bit farther on the stock internals.

In any case, 10:1 compression isn't very boost friendly.

[svxfiles]

YT was running 9 PSI successfully on his silver car. I believe a 12 PSI pulley resulted in broken ring lands. However, that was on a stock computer with the ECUTune software and no charge cooling. With a Hydra and water/meth injection (or running an actual intercooler if you go with a centifugal S/C) you might be able to go a bit farther on the stock internals.

In any case, 10:1 compression isn't very boost friendly.

Chris, you are wise beyond your years.:)
I have run 10-11 psi on stock internals knowing fully that it could go away at any (FUN FUN FUN) time!
But mine is a much cooler Jet Tech SC.:cool:

[TomsSVX]

12psi on meth injection is good so along as yo have it tuned... Otherwise 9-10 is good for a non-cooled charge bt obviosly wold be better off w/ some kind of cooling

Tom

[svxistentialist]

While I will bow to the knowledge and experience of owners like Tom I stick to my original response. 10:1 compression is too high for big boosting, regardless if you use a positive displacement blower or use a centrifugal type.

OTs point about the centrifugal type being less sensitive to low RPM detonation is a given, but this chap is using a Lysholm.

For long term use and engine safety you will be more secure with a 4-6 lbs pulley.

If you use a 7-10lbs pulley it won't blow up a good engine. Not straight away anyway. :rolleyes:

Anything over 10 lbs on stock internals is looking for trouble.

For the overall cost involved spend 500 bucks on a good water injection setup and at least gain the horsepower from the pounds you are boosting.

Joe

[TomsSVX]

While I will bow to the knowledge and experience of owners like Tom I stick to my original response. 10:1 compression is too high for big boosting, regardless if you use a positive displacement blower or use a centrifugal type.

OTs point about the centrifugal type being less sensitive to low RPM detonation is a given, but this chap is using a Lysholm.

For long term use and engine safety you will be more secure with a 4-6 lbs pulley.

If you use a 7-10lbs pulley it won't blow up a good engine. Not straight away anyway. :rolleyes:

Anything over 10 lbs on stock internals is looking for trouble.

For the overall cost involved spend 500 bucks on a good water injection setup and at least gain the horsepower from the pounds you are boosting.

Joe

You know Joe, it would be wise to aggree here... I tend to forget people are not *that* into R&D as I am... 6-7 psi would be my highest recomendation for longevity

Tom