Going to be doing a built long block faster than I'd planned. Broke the motor last night with the KB and 20 psi of boost. Now before you say "I told you so!" I think a built motor would have broken the same way.

Getting on the freeway behind a very slow vehicle so when I could I stood on it to pass in the other lane. Right before shifting out of second gear it nosed over and I immediately pulled out of it. Too late, melted a piston/plug(s) is my guess. Plenty of smoke, running on 6-7 cylinders, but no rod knock. Was able to drive it, and it still starts. LOTS of oil out the right side of the engine.

I'm guessing I just found out the limits of the stock fuel injectors and pump. I've datalogged it before in high gear and the A/F has always stayed in the 11.2-11.2:1 range, nice and fat. No detonation. Thing is no blower motor can handle going lean under full throttle.

My guess is the temps made the difference as I had done the full throttle tuning in the 90 degree range and it was only mid 60's last night.

It felt just like it ran out of gas, but the reaction to the nosing over just wasn't quite quick enough. My feelings are that I would have killed any motor in there. At least I didn't kick the rods out, lol!!!!!!!!! And no, I'm not going to try to warranty it!



I am open to fuel system upgrade recommendations though! Looking at 55# injectors and Bosch pump(s). Going to be swapping out for the SCT maf to go with their Pro Racer system.

Jody

 

damn thats alot of boost. any idea what you're going with for the build-up?

 

Have not made up my mind yet. I've got three engine builds going (or upcoming); my twin turbo, a friends aluminum 482 big block, and another friends 1300 HP single turbo 11 degree headed small block so I have no time to do this one also. Plus I'm a little leary as I've never even seen the inside of a modular motor.

Built short block and ported heads for sure. Cams are iffy as I have to be able to pass California emissions. This also means no LT's/cats as they inspect for the factory 4 cats. With those restrictions I'm not sure how much some mild cams will help, considering the stock manifolds and cats.

Obviously upgraded fuel system also! I want to be able to run 20 psi of boost, and I want to be well into the 11's. Better yet, I'd like to do it with 14-15 psi of boost and ported heads and possibly a cam swap will get me there.

Jody

 

It this the dreaded downshift that everybody claims is responsible for blowing these things up?

 

Not this time. This went from third to second downshifting around 40 mph or so, so pretty easy. It happened at the top of second gear.....right before the upshift it nosed over and then immediately upshifted to third.

Jody

 

So, you figure detonation even on a 11.1 A/F ratio?

Or do you think the stock rods just weren't up to the task of that much power for an extended period of time? JLP seemed to tell me that these trucks are hit-or-miss on the rods. He says he has seen stock trucks kick rods.

 

I think it leaned out (ran out of injector/pump). It nosed over right before the shift like it was running out of gas. What works for 90+ degrees definitely didn't work last night when it was 65 degrees. I figure it was close or on the edge before as far as pump and injector size and the cooler air put it over the top. Didn't hear any detonation.

Jody

 

Sorry to hear

While some here believe that the stock fuel system can support 500hp, I do not. I think your thought process on why the engine blew is correct.
Last year I saw what my stock fuel system was doing in the 4500/5500 rpm range (very lean) after the port job on the eaton with large pulleys. So I didn't hesitate to upgrade, as I knew it would be manatory later on.
Injector size, would depend on what your plans for hp are. But after looking at the pumps that are available, I went with the 255 Walboro WideMouth. When looking at the pickup, its like comparing a pencil diameter to a dime. It was a no brainer in my book. The electrial connection is a plug and play, put you have to enlarge the "C" opening on the mounting bracket for the larger pump. An easy fix with a die grinder.

Just watch out for that emission vacumn sensor on top of the tank, it breaks easy. It's a $47 item.....Don't ask how I know

 

Jody, this sucks sooooo sorry Bro

You described running too lean to a tee,
I use to experience that with one tune I had, week after
week I spoke about this "running out of gas feeling" I was
getting at the top of my 1320 runs

Didn't figure it out until AFTER I melted 3 plugs, (I was lucky and had no motor damage).

So sorry Bro

BIGGER AND BETTER ON THE WAY......WOO HOO