Hey, my b20 vtec 12.7:1 fuel pump 91 pro3, yesterday it broke connecting rod and block because of the detonation, when I made the timing I worked with an oil temperature almost 200F but yesterday I would reach 220. I'm going to build it again, I just want guidance on what margin temperatures you start to adjust the timing

 

1) That's where a really good tuner comes in, especially with that high of a CR on such low-knock resistant fuel. Get some race fuel additive or octane booster. even if its a daily driver

2) I won't ask why you're trying to e-tune this over a forum. It is utterly impossible to determine.

3)Either change your fuel.or change your CR with better pistons. Otherwise this will happen again quickly.

Let's see where this goes. if tuning input comes in, I'll set this to the engine management forum where it will get more traction

 

I just want to know how many degrees of margin to give when I don't get more hp advancing the map since when you tune it it's not at the same temperature that it reaches in a track day

 

Unfortunately, with this type of build that is not possible to determine until the day of dyno tuning and break-in. You can't "guesstimate" that kind of information.

 

You snapped a rod with detonation??

I've seen cracked sleeves.....

 

Yes one sleeve and 2 rods

 

That's not detonation, that's mechanical failure on the big end. At what RPM did this happen?

 

EXACTLY !!! More than 7K I am sure.

 

you mean the broke sleeve n3 made the n3 rod bolt come off and hit the n2 rod bolt?

 

anyway i'm going to mount the pro2s in the rebuild, not worth 700 rpm higer pro3 for 10-15 hp and less tq.

 

Yes. And drop the compression, or use better (higher knock-resistant) fuel. No more 91 octane for you. Find a fuel alternative, additive, or concentrate

 

Nope... either the n2 or n3 rod broke, sending parts flying and THEN cracked the sleeve and wrecked the adjacent rod. This happens from spinning a LS/CRV connecting rod above 7000 RPM. Big cams need to be revved to make power... a stock bottom end is a time bomb waiting to go off. Yours did.

 

the rod bolt were retightened 3 times ...

 

I am not sure what that has to do with the possibility of rod bolt failure... other than by torquing the bolt so many times, you may have stretched the rod bolt to yield. Either way, even a brand new bolt only torques to 23 ft/lbs. which means that the bolts inherent strength is 40% less than that of a GSR or ITR stock rod bolt.

 

To this day, I still have the doubt, the n3 sleeve was broken, then, the connecting rods flew due to the rupture of the sleeve or the sleeve broke due to the failure of the arp rod bolt?

 

I would suspect the rod bolt went first, especially if you didn't use a rod bolt stretch gauge.