hustler's "driver shame" thread
#1224
strange that your valves are bent on a non-interference motor. was there evidence of piston contact? strange that the intake valves were bent but you heard the air escaping from the exhaust side. how does a valve erode? too hot? is there something you missed in tuning? am i asking too many questions? not bustin' your *****, just feel as a pioneer of turbo track miatas in your region, you owe it to those that follow to report problems as they arise in your track beast. the cause and remedy are also essential to helping others. only other way i can imagine you bending a valve is thru severe detonation. the detonantion that would bend a valve, would also leave evidence on the piston tops. basically look like a hammertone finish on top.
lastly, why would you have to retune? did you just do your first tune a few weeks ago? no? i would have to guess that you tuned your car when you first put the absurdflow kit on. most likely pre bent valve stage, so no, you shouldn't pick up any horsepower from when you originally tuned it.
#1226
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It is still possible to bend valves on a non-interference motor. Not easy, but possible. If the engine spins fast enough then the valve has so much momentum that when the cam lobe pulls away from the lifter, the valve continues to travel towards the piston since the spring does not have enough force to reverse its motion quickly enough. In other words if there is severe valve float then there could be piston contact. Also, the springs could hit resonance and cause a similar problem. If you had a heavily shaved head, or decked block, or pistons with poorly shaped valve pockets, or a lot of carbon buildup, then that could also contribute.
I have no idea if this happens at 9000 or 19,000 RPM with a Miata motor but it is possible.
I have no idea if this happens at 9000 or 19,000 RPM with a Miata motor but it is possible.
Last edited by ZX-Tex; 10-30-2011 at 10:37 AM.
#1229
I was always shocked at your spark map and how low you run your boost. Looking at others' as well as researching many professional tuners' tuning methods, many usually like to run more boost and less timing to achieve similar power.
Now this may not be in any way shape or form related to your valve issues, I'm just putting it out there. It would be way easier on your motor that's for sure.
(disclaimer: drunk post so if its retarded please disregard)
Now this may not be in any way shape or form related to your valve issues, I'm just putting it out there. It would be way easier on your motor that's for sure.
(disclaimer: drunk post so if its retarded please disregard)
#1230
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I'll try to hit all of these:
Aparently they can float and the cam/lifter can hit the valve on the "way back up" and bend the valve. I zinged it a handfull of times and twice on the track. Once I missed 6th at MSR-C and another time I shifted to 3rd instead of 5th at TWS (CW). The trans moves way too much in this car, I want a Carbing brace.
I'm guessing that when at TDC on #1, air was leaking out the intake valves from #2, then going through the intake valves on another cylinder, out an open exhaust valve. The machinist said the exhaust valves all held water, all intake valves were a laugh.
Either too much heat, detonation...or bad metalurgy. One exhaust valve was eroded, not both, so the machinist says it's probably a valve from a bad batch. You saw the pics of the pistons and head, there was zero detonation.
See above, the pistons look great. The pistons look new and the quench pads are all smooth.
We'll see what happens with the tune. I'm going to zip-around town a bit the next time it's warm with the det cans and then make the decision.
lastly, why would you have to retune? did you just do your first tune a few weeks ago? no? i would have to guess that you tuned your car when you first put the absurdflow kit on. most likely pre bent valve stage, so no, you shouldn't pick up any horsepower from when you originally tuned it.
#1231
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I was always shocked at your spark map and how low you run your boost. Looking at others' as well as researching many professional tuners' tuning methods, many usually like to run more boost and less timing to achieve similar power.
Now this may not be in any way shape or form related to your valve issues, I'm just putting it out there. It would be way easier on your motor that's for sure.
(disclaimer: drunk post so if its retarded please disregard)
Now this may not be in any way shape or form related to your valve issues, I'm just putting it out there. It would be way easier on your motor that's for sure.
(disclaimer: drunk post so if its retarded please disregard)
These were the hottest cylinders:
I don't see how it would be any easier on the engine to run less spark advance. I agree with this logic in general, but consider the low static compression, tubular manifold, big turbine housing, big intercooler, 3" exhaust, no cat, and then the numbers make a bit more sense. Look at those pistons, they've been on the track with the tach hung in 5th gear at 6500 in 100*f heat and they look great.
#1232
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I could have, but I got these parts at great prices so I upgrayedded. I also want the stiffer spring to help out with the pressure from the turbo and the turbine sides. I got a set of new valves, seals, springs, retainers, and a hander for under $600. Those springs aren't going to last forever and they already had 70k miles on them before the build.
#1235
I could have, but I got these parts at great prices so I upgrayedded. I also want the stiffer spring to help out with the pressure from the turbo and the turbine sides. I got a set of new valves, seals, springs, retainers, and a hander for under $600. Those springs aren't going to last forever and they already had 70k miles on them before the build.
#1236
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what does a few psi do to the springs? turbo and turbine sides? i've never messed with my miata motor, but coming from honda and dsm world, we've ran up to 30psi on stock springs and never heard of an issue. is it a miata thing? now you got me scared on the springs, i've got over 220k on mine. how much time do i have left?
#1237
Did you decide on fuel lines?
I will stand by my recommendations from several pages back. Measure your stock feed and return line ODs, call Anthony at Imperial, tell him Chris Spalding recommended him, and that you need to get from X hard line diameter to whatever your fuel rail fitting is, and the other side of the fuel rail to the reg and to Y hard line diameter. Also, be sure to insist on stainless fittings, as he will try to save you a dollar with plated steel or brass fittings by habit. If you can go ahead and measure your lengths he will make up your lines and put some super bad *** Oetiker clamps on them, probably for free.
I will stand by my recommendations from several pages back. Measure your stock feed and return line ODs, call Anthony at Imperial, tell him Chris Spalding recommended him, and that you need to get from X hard line diameter to whatever your fuel rail fitting is, and the other side of the fuel rail to the reg and to Y hard line diameter. Also, be sure to insist on stainless fittings, as he will try to save you a dollar with plated steel or brass fittings by habit. If you can go ahead and measure your lengths he will make up your lines and put some super bad *** Oetiker clamps on them, probably for free.
#1238
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I'm doing Earl's 5/16" compression ferrule fittings (Savington's recommendation) and probably ordering $170 of **** from Bat-Inc tomorrow with black nylon braided hose. I went with the most cost-effective, reasonable prices...and great looking stuff.
I also have an order of bullshit from Mazdaspeed and I'm toying with the idea of a Mazdaspeed cam.
I also have an order of bullshit from Mazdaspeed and I'm toying with the idea of a Mazdaspeed cam.
#1239
I'm doing Earl's 5/16" compression ferrule fittings (Savington's recommendation) and probably ordering $170 of **** from Bat-Inc tomorrow with black nylon braided hose. I went with the most cost-effective, reasonable prices...and great looking stuff.
I also have an order of bullshit from Mazdaspeed and I'm toying with the idea of a Mazdaspeed cam.
I also have an order of bullshit from Mazdaspeed and I'm toying with the idea of a Mazdaspeed cam.