10lbs of boost, 9:1 compression 11.5 flat AFR, .35 gapped NGK's, MSD box and coil



I really have no idea whats going on.. Any ideas would greatly be apprecated

 

What does it do.

 

did you look at the dyno graph?

 

Where is your air filter located? I had a very similar problem with my Procharger and having the filter in an alternate location. Guessed that is was not getting enough air, cut out a hole and made a scoop and the problem was solved.

Mine happened at any speed above 70mph.

Just a thought.

Any pics of your setup?

 

Things to check are:

running out of fuel (what fuel pressure)
where's your timing set at
clogged cat

 

Is boost dropping off like crazy over 4k? What does the timing do over 4k? I agree about checking for a clogged cat especially if you have been doing a lot of tuning with it.. you should be able to tell immediatly if it's better when you drop the cat though.

 

I had something similar happen...it was a rubber elbow collapsing on the inlet side of my blower.

 

humm..

The car doesn't have a cat and the AFR stays in the mid 11's to early 12's so its not dropping off fuel pressure.

The entire intake track is steel so it can't collapse and besides boost isn't falling at all (this is a roots car)

I'm leaning towards spark blowout. It did the same thing with the last optispark and last motor and it did the same thing with a crane box (only a bit worse)

timing is very conservative and theres no major changes its a pretty easy slope. no spark retard being reported.

 

ps.. you can tell its going to be a monster especially for basically a stock bottom LT1. over 300 rwhp at 3800rpm!!

 

I would guess either spark blowout or perhaps floating valves.

 

I'm definately leaning towards blowout..

If you look thats where peak torque occurs which would be peak cyc pressure.. which would show why it starts hitting again when all this pressure comes down a bit.

I just really hate running such a small gap. I wonder If i should look into the LTCC

This project is a great gasmileage, economic and enviromentally friendly car and using the coldest plug at a small small gap for the 2 % of the time which i'm actually on the car hard doesn't make sense

 

hmm... any misses??

a blowout will miss I believe...

floating valves at 4k means damaged springs...

Have you checked your valvetrain?? maybe something is going out when rpms start to hit...

a lean out would break the engine and it rarely occurs at 4krpms

From what i see it then comes down and then back up.. can you send me a copy of your tune if its not prohibited?

highlander@caribe.net

If you have some kind of boost retarder it may be retarding huge for some reason.. it seems to me a spark problem there...

computer problem maybe, but that you know best

Send me the file and I will take a look at it...

 

when I had first put my procharger on I had a problem it didnt pull on the top like it should have, I put an MSD 6BTM on my car problem solved, I picked up .3 and 5 MPH just with that my spark was blowing out.

 

Clogged cat or fuel filter.

However, #1 choice would be spark blowout. A dyno graph would help. I saw try colder plugs gapped smaller and if that doesn't work, bypass the MSD box and try it again.

 

I had same problem turned out to be the MSD coil, put the stocker on and it fixed the problem.