Are new flex fuel motors really over 10 to 1 compression? How do they do that when running regular gas?
IMO, aluminum heads are a much bigger deal than is common knowledge; I mean beyond performance at WOT.
Some of us run deep into the 10s and into 11/1 Scr with them and tickle 200psi cylinder pressure, and run pumpgas. I myself, have run 3 different cams under some old Eddies. I started with the 292/508/108 cam, that I measured at
[email protected]. Then a 270/280/110 that was 223/230, and finally a 276/286/110, that was /is 230/237 . I adjusted the Scr in each case, to be in the zone from 175 to 185 psi............
to burn 87E10. That's a range of 23*@.050 or a tic over 3 cam sizes. Now imagine if I had DOHC heads and automatic cam-phasers on that 367, and didn't have to pull the cams out any more, or adjust the Scr.
IMO, there is more to aluminum heads that I don't understand. And it has to do with the way they shed heat.
If you have a set, you will notice how much heat they put into the underhood. It's a freaken oven under there. As soon as I had my engine broken in, I knew I was in trouble. That heat was cooking my IAT, and my carb was very unhappy about it.So the first thing I did was get fresh cold air to it.
So now that I had a stable carb, I came to a sortof understanding that the heads were shedding heat, like big radiators. So I upped the minimum coolant temp from 180* to 205*, and immediately thought I picked up a buncha torque. But if I thought it was hot under the hood before.... well, now, it was like Hades under there. So I took steps to get rid of some of that heat. And I took steps to make sure the cooling system was reliable.And now I was making some power, and loving it.
IMO, at part-throttle operation,those aluminum heads suck so much heat out of the chambers, that even at 11.3Scr , that 87E10 was not able to detonate. Even at near 200psi, I found no evidence of it. And I took that engine apart every winter 5 in a row. And so, I began to experiment with low-rpm timing and leaner running. And I found a good chunk of Part-Throttle torque. I think it was torque that should have been there all along, and with iron heads probably would have been, but the EFFECTIVE compression ratio just wasn't there on account of the energy in the fuel was going into heat, instead of the driveshaft. Running 205 gave me some of that back.
IMO though, as rpm rises, there is less time for the heat to escape or be transferred , and so the Hi-compression starts to make a nice fat PartThrottle torque curve. Then as the Rpm rises at WOT, there is even less time for the heat of combustion to escape thru the aluminum, and then that hi pressure makes a lot of power.
These are my opinions based on personal observations over the many years of running this engine, since 1999, and over 100,000 miles.
The biggest contributors to the formation of this opinion are;
1) In the one and only successful run I ever made, it hit 93 and change in the 1/8th, at 3467# . It's just a 367, with a 230 cam; it shouldn't go that fast. Mr Wallace converts that to over 400hp
2) it will idle down to 550rpm, with the 10.97 starter gear,( M/T) and pull itself around the parking lot, on flat,hard,level ground.
3) with a 223* cam, and overdrive, I could suck huge fuel economy out of it.
4) most gearheads that have been in it, think it could be a BB......
So,
IMO, if/when auto manufacturers caught on to this, (And I think those boys are way smarter than me), they brought us a whole new crop of hi-performance engines in plain wrappers, some/many with VVT. I only discovered this by the many,many, hours of on-road experimentation, beginning in 1999......cuz I wanted to know.....why this engine was so powerful, with this little 223 cam, and beginning in 2004 with the 230 cam.
So here's a winning street combo;a cam in the 225 /235 zone, aluminum heads at a minimum 8.7Dcr/185psi, and Q of .034/.040, and run her dependably HOT. And this is not on the "edge" yet, as I run it on
87E10 ALL the time, for over 100,000 miles.
If fuel economy is a concern, get the power stroke up to 112/115*. You can do this with a cam on the smaller side with a 110LSA; or, if you have an M/T,tighten it up to 106/104, and then stretch the intake duration out to 230/235. My next cam will be a SFT and target 235/241/104 and will spec at a minimum 68* of overlap, yet about 115* of power-stroke, to suck some energy out of all that hhhhhhhhhhhotness ; and I'm increasing the pressure even more........if I can find a thinner gasket to survive, I'm targeting 190plus psi.
Why?
Because I want to know.
And because I have those expensive aluminum heads, and need to justify the purchase, and they're too small for a stroker,lol. Ok, I just made this part up. I actually just want better fuel mileage.........lol.
Naw the real reason is; if it works, you aluminum headed 360 street-guys will hear about it, and never think about strokers ever again!
And
because they don't make DOHC heads for my 360 nor automatic cam phasers.
