wadzii

I havent had time to take the motor apart yet, but I looked at it with my bore scope.. there are chunks of piston missing.

I'm convinced that the damage happened on the low cam, high rpm detonation will almost always show itself on the spark plugs, I didnt see much of anything on the plugs.. I Had a hard time tuning out detonation while loading the engine at 2500-3500 rpms going up-hill, which is most of my daily drive.

I have a setup of non-vtec k-series rockers, I'll be using these when it goes back together.

Gernby

Ouch. Do you think the chunks of piston might have damaged the rest of the engine, or do you think you might get by with simply replacing the piston?

wadzii

I cant tell what all is damaged and I only looked in cylinder 4.. the block probably isnt usable and I'll probably need to replace the valves. Chunks of piston tend to beat up valve seats.

I have a few spares so its all good

Angerman

Hopefully your luck turns around pretty soon...

wadzii

I build these things to see what works and what doesnt.. that way when someone asks, i can say yeah, this is what p-w clearance these need, or this is what bearing clearance works, or no you cant run 13.5:1 on pump gas, etc.

I should have it apart next week.

franknbeans

Wadzii
Any updates????

wadzii

not yet.. too busy with customer builds to get any work done on mine. Hopefully I'll be able to tear it down in a couple of weeks.

TorqProject

with 13.5cr on pump gas you are getting detonation. It wouldn't happen on the dyno. It might start after a few laps and detonate violently during your part throttle areas. Most tuners miss out the ignition curve at transient regions. WOT is fine but what happens when you're at part throttle? If the pistons melted, you'll realise that the ring land area is running completely dry and expanded into the bores. The middle of the piston crown would look nice. AFR will not tell you whats happening inside the bores. You can have the motor detonating at 12afr, 11afr etc.

I've had several issues like that when running high comp motors on the circuit races. You need a good knock amplifier to pull timing when it starts to knock.

PM me on the camshafts. I've new 2012 billet spec cams available which will work for you.

wadzii

the detonation I was experiencing was not happening on the dyno on the high cam, the damage was done while driving on the low cam i'm sure. I knew it was going to be pushing the limits, but thats what I build my personal engines for. On an engine like this I start the dyno pulls on the high cam.

I have quite alot of experience making very high compression motors live on pump gas, but on k and b-series engines where I can easily choose a cam profile that works as well as easy access to adjustable cam gears. There just arent very many options for f series. Almost everything on the market still uses near stock idle lobes and with adjustable gears being of such high cost a high compression pump gas motor is just not really an option yet.

Brad Z is close to being finished with his cnc head program and I still need to find a good block.

TorqProject

Most of the engines that melt pistons happen during the part throttle and low lift cam situations. Alot of tuners only check for knock at WOT. How about part throttle at 6000rpm,7000rpm,8000rpm etc. They could well be detonating and no one knows because hardly anyone holds load tuning at 8000rpm. That is the problem. Tuners never encountered those knocking situations. Unless they datalog everything with a knock amplifier.

The typical ignition curve supplied by Hondata cannot be used with a high compression engine.

But you are right about the small Pri and Sec lobes for the F20/F22. They are too small and builds up too much compression at low revs thus the knocking.

Have a look at my billet 2012 camshafts. They have much better low lift profiles. I'm also looking at making camgears. Talking to some gear manufacturing companies right now.