Hi all,

After a long hot season I've finally gotten the first couple hundred miles on my new build. I think I'm ready to bring it to my Dyno guy who's about an hour and a half away.

I waited until now to do the compression test and ensure rings were set etc.

Hoping you can tell me if the compression results are fine and what ultimately they mean to me if anything:

Everything was purchased through Kirby at Veetwin (amazing as always), installed by myself.
Build is S&S 107in cylinders, Wiseco pistons, stage 2 heads, .030 head gaskets, 50mm TB with 4.9 injectors, HPI AC.

First crank had the rear cylinder at 215, but each one afterwards had it at 200 on the nose.

Front cylinder also 200 on the nose.

Questions:

1. Should I be concerned that I couldn't duplicate the first reading on the rear cylinder?

2. Since both read 200 now, how do I correlate that to my compression and what does it mean to me?

thanks as always!

 

Ok, edit time...

REalized that I wasn't holding the throttle open during the test. Once I did this both cylinders registered 215 each time.

Throttle fully opened cranking until needle stops. Engine cold, charger plugged in.

 

What are the projected numbers suppose to be?

 

I'm not sure. I bought the heads and Fueling 574 cams from Kirby over a year ago and they went on the stock cylinders/pistons with a .030 gasket but I don't have the notes from the build anymore. Maybe 10.5:1 sounds familiar... If it helps the heads were 81cc. I added the cylinders and pistons a couple months ago, but it's taken this long to get break in done.

 

107, .030hg, 81cc, and 574 would put you at 9.78 corrected and 206 cranking.


This is zero deck height and 1.5cc for valve pockets. Best I can do with info I have.

 

Gotcha thanks! it cold cranked at 215 so guess that's pretty close?

How does this effect the engine performance? Guess I should go google, unless someone wants to share the cliff notes version

 

I'll look in my records & see where they where set right after the hurricane

 

215 is a lot for the street and you should look at may be knocking your timing back a little bit cuz it's going to tend to get hot with that type of CCP...

 

It does get hot!

 

Stay safe Kirby!