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boost alone isnt necessarily what makes rods bend or break, he probably has a good tune that doesnt detonate at all.
even at 30 psi cylinder pressures are like 1000psi on the high end, iirc.
Evem mild detonation spikes pressures to twice that.
he doesn't run any less timing or any fatter afr's than most people on here.
but I kinda agree, the key here is low cyl pressures, and that the car is trapping 105-107 indicates he's not making that much torque.
my buddy was trapping 114 on stock BP05 on e85 for a while before venting the block
if his cyl pressures weren't being bled off, 29psi and 10* of timing would net WAY higher trap speeds
Well I stand corrected. I honestly don't know how your motor is still together.
At the track, he's running high boost levels at higher RPM. VE is down at the higher revs vs say, 4,500-5,500 where the enigne's VE peaks. So higher revs for a given boost results in less cylinder pressure after torque peak, AND less chance of detonation due to the higher revs.
Ok, you guys really want to know what is holding my motor together. Spit, bailing wire, zip ties, along with this wrench and the duct tape from the guys at the track.
"Danger"
Unfortunately I believe that much of the boost slips past my rings, which is why I struggle to capture crankcase fumes. Also why I am so slow(like a mustang GT) running so much boost.
I need to just buy some rods and perhaps pistons from Andrew already, and get on with it.
Give it some very stiff valve springs, rev to 7800-8000, setup flat shift to hold boost between gears, and you trap speed will go up 10 mph. With tires ET will drop a ton.
I run the supertech heavy double springs, and they seem to work well in my experience. That said if I were buying again I'd try to find something that uses a variable diameter spring, I have seen a post here of someone who got them for their miata.
Trying to decide if I want to go to the bracket drag race tomorrow morning. The weekend/holiday events are not as much fun as Wednesday night, which is the following night. Also I will need to be there by 8AM or something and I obviously didn't go to sleep yet. I will check here in the morning, but unless someone is hoping to beat me while my car is slow like a new Mustang GT or SS Camaro, I probably won't go.
Unfortunately my motor didn't like 310kpa, luckily I just started honing my next block.
I was winning but I hit overboost and my car started rattling, so I had to quit, made it home no problem though.
There was a cool drag bike and a couple Honda civics running low 12's.
I ain't even mad, this was the 196th1/4 mile that finally blew my **** up. Operator error, too much boost. The real question is if I can get this done by the next drag race. Looks like Andrew is on vacation so I need to wait to get my rods. On the bright side, no need to source a high dollar head core.
Thanks Marcello, at this point I have enough broken pistons, rods, rotors (yeah rx7 rotors.) Honestly, cherry rods and pistons from stock blocks are much prettier IMO.
I will post my dying log in a day or two. Only 36 or 37% boost duty to manage that, hit my boost limit almost at the finish line, top of 4th.
Oh, and for people who want to make a crazy wastegate can like mine. I had trouble making it work correctly and this is what happened. I still plan to use one on the next motor though.
Yeah, well I'm just a guy abusing my tired *** hoe made ****, who's secretly been hoping to blow his motor since it's been getting slower and slower anyway. The guys at the track were amazed that I wasn't upset. From my perspective this motor should have let go long ago.
Oh, and I was able to run 14 or 15° at 300kpa on camel **** 91. No you can't, that was just manifold pressure.
I honestly don't know what is wrong yet, still runs normal, just doesn't sound normal. It is unlikely but possible that I just busted something under the valve cover, or maybe a bunch of my harmonic balancer bolts broke. Not very likely though, I will share pics of whatever damage I find.
06-29-2017, 07:43 PM
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