Built motors and detonation
12-21-2009, 04:00 PM
#101
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Hey, Eurotrash...I'll be able to see perfectly smooth piston tops, unlike the dimpled cottage cheese *** you have to live with from going through life as a beta-male scavenger. A leak down won't show phantom detonation, but it will show that you're a latent homosexual, living the hetero lie.
I disconcour. Couldn't a piston be melting/hotspotting in various places without leakdown symptoms? Isn't leakdown rings? If your piston is melting and getting brittle I'm guessing detonation will break it more easily. If you saw signs of fuxage at least you could try to do something about it before your piston dies and scores up your cylinders etc.
- have knock detection (on the dyno: detcans and preferably in a closed loop ECU)
- tune for safety (a few degreed south of detonation and a tad richer)
Leakdown is valves, rings, everything. Basically leaks...
So, bore comes out after you identify an unknown issue, not to measure health.
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01-15-2010, 05:00 PM
#105
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So this is a little off track but I guess this is the right thread to ask in. If I wanted a 300-350whp street car that was "relyable" (could take it on day long road trips and maybe dick around at the track every once in a while) would some forged turbo pistons (Wiseco for instance), some stronger rods (Carrillo a-beam or h-beams maybe), and ARP head studs be enough? I'm guessing that would equal 15-20psi on a 2860. Oh and would this be possible on pump gas?
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01-15-2010, 05:04 PM
#106
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Probably don't even need the head studs, but an ATI damper or billet OPGs is a good idea. You won't make 350whp on a 2860RS, though, and without a stroker motor and a 3071R, 350whp on pump gas without water injection is going to be tough.
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01-15-2010, 05:38 PM
#109
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Oil Pump Gears. I don't think anyone has had a head gasket failure and pinpointed the cause on stock head bolts. I use ARP studs, though - there's no downside aside from the cost (and it makes the head much easier to install).
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01-15-2010, 05:44 PM
#110
MX5autoxer I'm in the middle of the same thing. BEGI s4 w/ 2860, 2 1/2" enthuza, MSpnp. I have RX7 550's.
94 1.8L putting in Wiseco's, M-tuned rods, OPG's, all new gaskets, ARP head studs, DIY head porting. With the 2860 and my 550's I"m figuring 300-325 is the upper limit. Beyond that bigger turbo, bigger injectors and WI will be needed.
94 1.8L putting in Wiseco's, M-tuned rods, OPG's, all new gaskets, ARP head studs, DIY head porting. With the 2860 and my 550's I"m figuring 300-325 is the upper limit. Beyond that bigger turbo, bigger injectors and WI will be needed.
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01-16-2010, 08:33 AM
#111
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I'm a newb here so take it for what it's worth...
In the piston pictures all failures are near the valve reliefs. It is well known that sharp pointed objects in the cylinder get hotter, faster than thick smooth places. If I had those pistons with the machined valve reliefs I would consider smoothing them out. Each failure started with a hot valve relief edge and then torched down the side of the piston.
We run a pulling tractor on Meth with staged turbos @ 70 PSI and have seen a few torched pistons before. Usually from a lean condition on one cylinder.
Broken ringlands and lifted head gaskets without the big torch spot is from detonation IMHO.
In the piston pictures all failures are near the valve reliefs. It is well known that sharp pointed objects in the cylinder get hotter, faster than thick smooth places. If I had those pistons with the machined valve reliefs I would consider smoothing them out. Each failure started with a hot valve relief edge and then torched down the side of the piston.
We run a pulling tractor on Meth with staged turbos @ 70 PSI and have seen a few torched pistons before. Usually from a lean condition on one cylinder.
Broken ringlands and lifted head gaskets without the big torch spot is from detonation IMHO.
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DUUURRR
01-16-2010, 03:10 PM
#120
They've found ways to make turbo engines that generate 130-150+ hp/liter live free of det-induced destruction for ~150k+ miles despite production variation, inconsistent octane and owner neglect. And they do it with basic rods, high compression, cast pistons, skinny ringlands and in some cases open-deck aluminum blocks.
Then I'd find a way to employ the relevant hardware/strategies on the Miata engine.
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