Failure Brainstorm/Brainfart
- Thread starter DaJokr
- Start date
How high? Is there an ideal rpm to have the power come on? Would a person want to try to push past 4k or still keep it under 4k?
Started going through toms threads, wow. Lotsa good stuff in there. Gotta go through each thread he's started from the very beginning...
My thinking is this, if af cam reduces torsional twist in crank (fighting each other)(again NOT proven) then you would see some reduction in stress on connecting rods. JMHO. Could very well be wrong on that.
In my opinion, the biggest issue is valve float due to the super-weak stock valve springs. Honestly, it is hard to get the air the motor needs to make power up that high on stock heads/cam anyway. Most people seem to shift at 3500-3800 RPM-- if they have the turbo(s) to support that.
As for stock valve train, I have the stock lifters, pushrods, and rockers. (SoCal valve springs, retainers, etc). I see 4000 RPM without issue, but I'm totally out of air up there. I've done a few burnouts on the limiter (4800 RPM), and besides black smoke (my poor S366...), the motor was perfectly happy. It sounds wicked with the cam!
But that is why I say the biggest problem is the stock valve springs. That being said, I only have ~4000 miles on the motor, so maybe I'll kill it yet.
Bottom line, I don't think there is any point turning a stock motor faster than ~3800 RPM; you just can't stuff in the air. Potential valvetrain damage notwithstanding.
Used my stock (300,000 mile!) LB7 hollow pushrods. About 2,000 miles after the build I had to pull a head (cracked intake runner), and valve lash was all exactly in spec, despite a couple 4,800 RPM pulls. Before the build, I talked to a couple people at ATP, and they said they had seen lots of builds survive with stock pushrods.
I reused a lot of stock parts that people don't necessarily recommend reusing. If I do manage to kill this motor, I will post up the teardown, so at least we will know what parts not to reuse. Which reminds me, I need to get around to posting the build thread. Maybe this weekend, if I get a minute to myself. There are already some fun lessons-learned I should share. Plus, that way I stop derailing this thread.
Interesting on the float, I thought it was just the water pump that had issues over 4k, didn't even think of the lifters. I see a little over 3900 with my current tunes, might need to look into getting that tweaked a little for now.
Tom your build is interesting to say the least. Lots to learn from there.
Tom your build is interesting to say the least. Lots to learn from there.
Rob added 200 or 300 rpms to my lmm and it really woke things up with the 4094. Im not sure if Marks turbo likes the added rpm though, but I know my 4094 did. It was an animal over 3k...