max boost?

[poloeatonm45]

Hi all just wondering really what is the maximum amount of boost you can safely run through the py lump before u are pushing the limit of things such as head gaskets i have seen people run 22psi on an eaton convertion but i have not heard any reports of how reliable that is nor have i seen anyone run a higher boost level than that.

Steve

[GR40]

I have been running a stock engine with an eaton and 1,2 to 1,3 bars (17,40 to 18,85 psi) no problem at all for the past 5 years I am running this set up! The biggest problem going over that pressure will probably be the stock injectors and the amount of fuel they can feed the engine or the engines mapping as the ECU cant see more than 1 bar!

[dub-disaster]

I have been running a stock engine with an eaton and 1,2 to 1,3 bars (17,40 to 18,85 psi) no problem at all for the past 5 years I am running this set up! The biggest problem going over that pressure will probably be the stock injectors and the amount of fuel they can feed the engine or the engines mapping as the ECU cant see more than 1 bar!

You can always fit lager injectors and map sensors to solve this. As for max boost hayesey runs 21 or 22 psi on a standard bottom end. I think the weak point with a standard bottom end is the cast pistons which melt when cylinder temps get to high which can be caused by using more boost than the map is ment for or working your compressor too hard so it produces lots of hot air.

So as long as your engine is set up for it I think it may be more a case of how much air your compressed can flow at what pressure rather than how much your bottom end can take.

[poloeatonm45]

Huum the reason i asked is because im runnin my eaton set up with around 20. 22 psi but am having head gasket probs and was wondering if the high boost level might of been a factor

[Jezza-7]

What head gasket is it?

[poloeatonm45]

Just a normal paynes head gasket i usually use

[Justin14100]

Whats the map like? If its running lean it could be overheating and blowing the gasket? or is it just going without cooling issues?

[poloeatonm45]

dont think their is any cooling issues i have a 16 row oil cooler and a brand new g40 rad on it so should be keeping it cool. the map should be ok its a psd one for an eaton convertion made to run ever so slightly rich i think thats what they said

steve

[PeteG40]

some gaskets are listed for g40 ( and other 1.3s) but actually arent g40 gaskets

also are you using new head bolts? and has the head been skimmed?

pete

[poloeatonm45]

ahhh i think it was a g40 gasket but will check the head was skimmed but we didnt used new head bolts but we have done the gaskets on many polo engines berfore and always got away with old bolts but i will get a new set the next time

[poloeatonm45]

Took my head and the gasket that went to a shop that i normally use and they recon it failed because of too high cylinder pressure and too maybe a slight ignition prob the prob is he said he can skim the head again for me but that will incrrase the pressures even more so my question is how do i lower the cylinder pressures?

[Andy]

You run lower boost or lower the compression ratio.

But skimming the head on a Mk3 Polo makes very very little difference to the compression ratio, so I wouldn't worry about cylinder pressures.

If it looks like detonation damage, what chip and MAP sensor are you running at 20psi on your Eaton? Can you hear it pinking?

[poloeatonm45]

Their are no marks at all on the head its hard to explain but the gasket is covered in little dimple marks all around the rings for the cylinders the only way i can explain it is its like the pressures inside the cylinders have been trying to force past the gasket. Alsothe rest of the gasket was showing signs all over of almost going. Bare in mind the gasket had only done 30 miles and the gasket before had only done 30 miles too. At the time i was only running 18psi max boost but to be honest i was takin it really easy as i was only trying the car out to be honest as the gasket had already gone once. Yeah u can hear it pinkin if you put your foot down.the map is a psd map running rich at the top end the map sensor is stock but like i said i was only taking it easy to check the car out so it was never going above 15psi.  Its running red top injectors so their should be plenty of fuel getting in .

Steve

[Andy]

If its pinking its arse off you're lucky it's just the gasket that's going.

[PeteG40]

i'd say

1. get head properly pressure tested etc.
2., ensure block is flat
3. get a decent quality gasket and new bolts
4. once running, get it mapped
5. enjoy!