Compression Check

[Neville Lush]

TA, I think I gave my answer already......"You do not need more comp at all if you are planning using stock cams. As described in other posts the Rocket is a low compression engine(8.7) but has HIGH cranking pressure. " As above. I have had 9, 9.7, 10.2 and 10.5 from JE and they do 11.8 for dragracers all for rockets, so they do whatever.As to prices maybe call them?

 

[Torque addict]

I'll call JE and see what they'd charge for a set of 8.7's then.

Scott, those pistons are pretty! I like the idea of a thicker ring land!

 

[Torque addict]

Decided to have a baseline dyno pull done for comparison purposes after the rebuild. Interesting results! Another piece of the puzzle.

My AFR is totally off! Check out the attached PDF and compare to the tune I posted earlier. I'm lean everywhere and dangerously lean between 2.7k to 4.2k and 4.5k to 5k. He was surprised I was riding it at all and that the rings weren't melted to the spark plugs. There's a fuel delivery problem somewhere!

This, folks, is the reason for a fail safe AFR gauge! I will probably be going with the AEM:

The failsafe will cut the boost and switch to another map that pulls out more timing.

Max power was still there and surprisingly close in comparison to the dyno at Latus Motors. HP only down by .5 and torque down by 7. I was happy to at least see that and I can definitely feel the power loss between 2.7k and 4.2k so it's good to see empirical data for that.

If you want to see video of the dyno pull this link should hopefully work:

Also had a good discussion about pulling timing respective of boost, rpm and throttle position. Nels knows what he's doing. The fuel management system and tune will be correct when we're done with it.

 

[warp9.9]

Great to Hear !!!!

 

[Torque addict]

And here's what I found. Busted 2nd and 3rd piston lands. Yep, that'll lower the compression! I will start a new thread on this as I have a few more pics and vids I'd like to post with a few observations and questions.

New thread here: http://www.r3owners.net/threads/broken-piston-top-end-rebuild-turbo-motor.22292/#post-321116

 

[idk]

Ouch!