Race Engine Forum UK

Hi all!
Yesterday i decided to do a compression test on my engine Approx 2500 miles after rebuild.... I've run it in gently for the first say 1300 miles, then i upped revs a little till i got to 2000, then drove as i normally wpould for the last 500 miles..
for the first 1300 miles boost pressure was only 0.5 bar... Anyways... the results of test were:

1:136
2:136
3:141
4:141

Do these seem about right?? some guys on the Fiat coupe forum seemed to think 165-170 was normal????
I have had headwork done, wossner pistons 84.4mm, C&b (stradale massimo) cams, cosworth t34 turbo, tubular manifold...
car is yet to be mapped!!!

http://s132.photobucket.com/albums/q27/ ... 286b94.pbw

Nick

It is low for a standard Coupe. However the cams will give a lower than standard test result.

Never read too much into one dry test, OK?

Do a wet comp test now. Oil up the bores with a few squirts of engine oil down the plug holes and test again.

All plugs out, hot engine, wide open throttle, crank till it stops rising.

Please post results.

Caution: a poor quality gauge will give misleading results! I actually recommend Sealey's one - low cost and very good indeed. Never gone wrong on me. Top of the range: Snap-On.

GC

Make sure you unplug the crank angle sensor or similar so it wont inject fuel or spark while peforming the test.

Wossner list a dome of -38cc for their pistons. That is a big empty space! If it is not a misprint, it could be your issue.

yes, it certainly would be if true!

I've just done a new design for 16v T pistons, (with inlet and ex VRS) 22 cc dish, 38.4mm comp ht, at 85mm 7.5/1 CR which would suit up to 20psi boost. I could have done a bigger bowl but I chose to run the pistons fractionally low in the bore.

GC