Found a 10:1 compression 1994 Diamante 3.0 in the junkyard. 190,000 miles but it looked like the last owner had actually worked on it, even removing valve covers etc. Not sure why the front head is so clean. Even the other head is very clean, and all the journals look virgin. The Bearings in the motor looked almost new. The only high mileage indication was that the piston oil rings were locked up and all the return holes were plugged with coked oil. Went through and cleaned it up. Bolted on my ported/cam'd heads because I found the top ringland is too high for me to feel comfortable running as much boost as I had planned on stock heads (30ish).
Actual compression will be more like 9.7:1 with the 51cc combustion chambers vs 46-47cc stock.
Main upgrade with this build is a 1000hp fuel system.
-Twin parallel GSL392 Walbro 255lph high pressure external pumps. Hotwired to 14v. Gravity fed.
-Using 2 stock 5/16" feed lines. One for each pump.
-Parallel fuel rails, 1 pump/line feeding each rail.
-single return line.
-Jaz 12 gallon 2" sump fuel cell (70-10ohm fuel level sender), twin -8an outlets. -6an breather. Added 3/8" barb for return line.
Enough fuel for 1000whp on gasoline or about 750whp on E70. Thats conservative. I have 2100cc's of methanol which can support another 150whp but my meth pump is still fubar'd right now.
So total fuel capacity is 1150whp on gas, 900whp on E70.
I might run E95 in the future which will drop those numbers quite a bit. But those numbers are conservative. If I need more fuel I can up the fuel pump voltage or change to twin Denso 044 pumps.
Honda guys are making 890whp on a 5/16" line on alcohol! Using a Walbro in tank and Denso 044 in series. I don't want to push that hard, and I will temporarily be running very high fuel pressures (my MSII is in the mail but I don't see it getting installed soon).
I figure this motor will make 450whp uncorrected on 15ish psi. With megasquirt, a lot more as I could take the cam gears back to stock and pick up a lot more on the top end with higher rev limiter.
These heads did 447whp uncorrected (at 4400 feet)on 20psi with only 7.0:1 compression and massive blowbye so 9.7:1 and better ring seal should have no problems keeping up, especially on E70 fuel.
I think its going to make some freakin insane hp and be very peppy with the higher compression. With Megasquirt and another 1500+ rpms to rev and non advanced cam timing, it should be a beast even on low boost levels.
I am interested where this motor will start to spool the turbo and then get full boost. Maybe the powerband will widen enough to prevent me from dropping out of the powerband on shifts with these heads on stock rev limiter.
If I don't pop this motor, then i will probably donate the shortblock to my daily driver and think about buying some forged flat top turbo friendly pistons. My 7.0:1 Venolias were beasts, withstanding 15-17:1 leanouts in the 400+whp area.
I was going to built a 24v 3.8L Mivec with compound turbo setup but I might stick with this since I cant really afford that route right now. My fuel system is sorta overdone in case I build the 3.8L, then I will be just a few fuel mods away from being able to support a 1400+whp compound turbo setup.
Some top rings were gapped as small as .012"!!!
Now top are set to .024" or more depending on cylinder location and 2nd ring is .030-.032 depending on location.
For some reason the stock 2nd rings were gapped larger then the top rings which is NOT normal for motors built 15+ years ago. Not sure if its because of the high compression pistons or what. Only recently have people started gapping 2nd rings larger in almost all applications.
Cleaned out clogged oil return holes and then drilled them out larger.
Piston on the right is a broken 8.9:1 1992+ 3.0 piston that has a lower top ring location then the 10:1 piston.
.014" copper wire surrounding each combustion chamber. Superglue ftw. Copper spray ftw.
Stock Mitsubishi Diamante knock sensor. Not sure how to take advantage of it. Knock sense is a possibility but not sure.
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1000+whp worth of fuel
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