Originally Posted by dstn2bdoa
(Post 635175)
I'm interested in how this is turning out.
The spec sheet, that came with my supertech 85.5 9:1 pistons that I bought from emilio said this: Application: Factor: Street Performance 0.0045 Moderate turbo / Nitrous 0.0050 Drag/oval track 0.0055 Turbo/nitrous race only 0.0065 My builder and I decided to go with "Moderate turbo / Nitrous" 0.0050... |
Thanks for stepping in and correcting this confused motherfucker, so I don't screw up some other confused motherfucker.
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FWIW the box of FM 2.0L Wieseco pistons come with a spec sheet from Weiseco that says "recommended piston clearance .0030" Seems like supertecs with lower thermal expansion could be tighter.
Bob |
What would you suggest on a street engine that is going to be running 1.7 bar daily and possibly 2.2 -2.3 bar on meth at the track?
i dont want to go crazy loose and have it be essentially a full blown drag car... I will be using supertech pistons. |
Originally Posted by shlammed
(Post 643788)
What would you suggest on a street engine that is going to be running 1.7 bar daily and possibly 2.2 -2.3 bar on meth at the track?
i dont want to go crazy loose and have it be essentially a full blown drag car... I will be using supertech pistons. |
Not to mention the fact it is going to be difficult to keep it all cool, engine, trans, and diff, at those power levels, on the track. I am assuming by track you mean road racing. Bring lots of $$$
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Originally Posted by bbundy
(Post 643722)
FWIW the box of FM 2.0L Wieseco pistons come with a spec sheet from Weiseco that says "recommended piston clearance .0030" Seems like supertecs with lower thermal expansion could be tighter.
Bob |
Originally Posted by faeflora
(Post 643796)
30-32 psi? Seriously? You do have a good setup but that 2871 will kinda be falling off the map at those boost levels. My thoughts are that the high hp mixed street/strip Miata engine should be built the same way as a high hp street Miata engine.
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Originally Posted by shlammed
(Post 643810)
the turbo is getting FP HTA wheels. they are efficient to ~40psi.
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would be nice to make 350-400 on a 1.6 at those levels.
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So you don't need anywhere near 40psi to make those numbers, then. With a good intake manifold and race gas, 400whp is probably doable in the 27psi range on a 1.6 and a genuine 2871R with Garrett wheels. On pump gas for the street, I wouldn't push much past 21psi which will get you right around 320-330whp. If you have E85 available, 400whp is probably doable at ~24psi.
Don't bother with the FP wheel upgrade, keep your Garrett warranty intact since the Garrett wheels are still efficient at 27psi. |
i was going to get it setup with the current turbo and then get it done later... my brakes need attention before i get a brand new turbo rebuilt.
plus i meant 32psi to make 400... not 40. i just stated that it is effecient to 40 with FP wheels. |
Originally Posted by falcon
(Post 634698)
Less air being forced into the combustion chamber = less compression of the air/gases = less heat.
Compression is not based on how much air you put in. If I run my motor super rich, enough to wash down my cylinder walls, my compression doesn't go up. Or down. Or whatever you think. lololol Ps, has the motor been built yet? |
Originally Posted by scottyd
(Post 643874)
Wait, wait. How did nobody else see this?!
Compression is not based on how much air you put in. If I run my motor super rich, enough to wash down my cylinder walls, my compression doesn't go up. Or down. Or whatever you think. lololol Ps, has the motor been built yet? 2. Compression doesn't change with boost pressure.. static compression doesn't. That is determined by the pistons, valves etc. etc. Dynamic pressure does change greatly which is where the force that damages pistons, bends wrist pins, buckles rods etc. comes from. 3. More pressure always equals more heat. If you can make more power on less boost and have an efficient turbo, it's a very good thing. |
Originally Posted by baron340
(Post 643920)
1. Fuel has nothing at all to do with compression.
2. Compression doesn't change with boost pressure.. static compression doesn't. That is determined by the pistons, valves etc. etc. Dynamic pressure does change greatly which is where the force that damages pistons, bends wrist pins, buckles rods etc. comes from. 3. More pressure always equals more heat. If you can make more power on less boost and have an efficient turbo, it's a very good thing. |
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