13 replies to this topic

[mini_me]

Does anyone know how to measure the combustion chamber size? Im gonna have a go on an old cylinder head so as not to wreck my turbo one. Hoping to lower the CR. Did at one time know how to calculate it, but have since forgot??!!

Cheers. :grin:

[Turbo Phil]

This is how i do it.
Get an flat piece of perspex, such as on a CD case. Drill two small holes {1/8" should be ok} about an inch apart. Take your cylinder head and smear a thin layer of grease on the head face around the edge of one chamber. Now press the perspex/CD case onto the head face so both the previously drilled holes are over the chamber. Take a cyringe filled with oil, noting how much it contains, and proceed to fill the chamber through one of the holes in the perspex/CD case. The other hole will allow the air to escape. All you need to do now is note how much oil the chamber holds. Da Da !!

Hope this helps.
Phil.

[mini_me]

Yeah thats it :grin: same way i used to measure piston dish cc! What cc would you recommend i take it out to? Is it possible to lower the cr to around 8:1 with just head mods?

Cheers! :grin:

[Turbo Phil]

Is your engine standard Turbo motor ? using standard head gasket etc ?

Phil.

[mini_me]

All standard at the the moment but might be going to 1293 running about 10psi with intercooler.

[wolfie]

if you pm your email ady mate ill send some pics of mine if you want

[ditz]

if you pm your email ady mate ill send some pics of mine if you want

dont suppose you could post them could you?
i would like to see aswell

[mini_me]

What cc have those chambers been taken out to? I take it the bottom end has been well rebuilt! What setup are you running to get that much power?

Cheers. :grin:

[wolfie]

29cc mate
belive it or not i cobbled the engine together its had no more than an mg cam and a +20 rebore with budget pistons
did not last long at 12 psi lol

[mini_me]

I was enlarging the combustion chambers on my head today and found myself in an arguement with a friend from another garage, his arguement was that, what im doing is wrong and there is no need to increase the chamber size. I told him it was better to do this as i would be able to run more boost safer, also the car is on its limit with the standard cr 9.4:1. He reckons that i should be looking to keep the compression as it is and run 4psi of boost with an intercooler. Also according to his tech info database, the cr for a metro turbo is 8:1? I value all his comments but am now unsure if i doing the right thing!!?? Also has anyone got any ideas on an spi turbo with a high boost solenoid controlled injector with a closed loop lambda?

Cheers! :grin:

[Turbo Phil]

The Metro Turbo is deffo 9.4-1 compression, and ran 7psi max boost with no intercooler. So i can't see the point of running only 4psi .....
Anyway, opening the chambers is the way to go in as far as it's the cheapest method and has the desired effect of dropping the compression, though you do lose the optimum "heart" shape chamber, but this is the way most folks go.
Carry on mate !

Dave Coxon's your man for injection info ! :wink:

Phil. :grin:

Attached Files

•  chamber_mega_head.JPG   333.56K   12 downloads

[mini_me]

As i thought! I know you lose the swirl effect but this is made up by the fact that theres much more power to be gained! Plus its cheaper than the auto on boost retard module that avonbar sell. Thanks for the boost in confidence!

Cheers! :grin:

[DaveCoxon]

I'd love for someone to throw an MPi or SPi mini my way and say somet on the lines of "I want it turbocharged, but want to remain on the factory management"

Boy would i relish that challenge. But - I (like to think) know what i'm doing. It'd be really easy for someone who didn't (but liked to think they did) know what they were doing to melt a piston...

Make life easy. Stick an SU on it and blow through that.

[mini_me]

Well i was thinking along the lines of a second injector for on boost to avoid lean out, dizzyless ignition with a turbo ignition management module, intercooler, only 7 psi and running a slightly higher cr and possibly a mapable ecu. Trying to go for something abit different! But perhaps not spi probably stick with the hif44.


Cheers! :grin: