Well, I think I figured it out...

[christianmb]

Well, after having a plague in the engine since the end of August, I think I finally figured it out. It was running GREAT cold, then as soon as I went into closed loop, it would cough, backfire, sputter and had no power above 1500RPM. I looked at sensors, ran datalogs, code scans, etc. I ran a compression test and I got 85# front cylinder and real cylinder pumped up to 120# after adding oil to the cylinder. Judging from these results, I think I have a blown head gasket on the front and ring problems on the rear.

Since I will need to dive into this again, I am pretty much going to send my heads in to get a 30-degree squish band milled on it, and a competition valve job done on it. I am also punching it out to 1250cc with custom pistons and jugs courtesy of hammer performance. Getting new gaskets and pushrods. Any feedback on hammer performance or the mods I listed would be welcomed. I end up getting 12.5:1 compression out of it. Any ideas on additional mods or how good Hammer Performance is? I'm completely open to suggestions.

 

[fireinxb]

Are you going to be running race fuel or e85 at 12.5:1 compression? I've heard that even a good 11.5:1 compression ratio will ping on pump gas.

Otherwise build sounds solid. In for results, because my bike will definitely have a built motor one of these days..

 

[DIRTY T]

I am going to have them do a 90" kit for me this winter. there great guys there...are you changing cams as well?

 

[dallasb]

Compression ratio really isn't the deciding factor on the type of gas that is recommended for the application. You should be able to run 91 without any problems with early detonation. If you are having issues with pinging then adjusting the timing can fix this issue. Sounds like a fun build let us know how it goes.

 

[Rhino1]

Ever consider the XB9 pistons? Seems that they work out great and you won't have to worry about preignition due to excessive compression...

 

[christianmb]

I'm not putting in different cams...this year. I'll see how it goes for now. I know I have had cars that have run high compression, so I'm not that worried. I have the bluetooth ECM interface that I bought from xopti and the Android app, so logging will be super simple. I'll make sure to get the right tune in her before I romp on her. I also plan on having it dyno tuned if I don't get to trigger happy. I thought about going 90ci, but I am not 100% sure. Then I would want to open up the header and bigger valves... By the end of it, I would have a race prep motor for it. Wait, that isn't a bad idea!

Oh, and I looked at the XB9 pistons, but I want to get the benefit of the 30-degree squish band. Since the "9" pistons would give me 0 degree, which is quite inefficient, I figured the custom milling and pistons would give me a little better performance. I'm hoping for 100+ RWHP by the time I'm done, or at least close (off the showroom it was 83)