who's got the highest compression?

[rockthemullet]

The Ecoboost motors are direct injection engines, you can't make any kind of comparison of detonation tolerance for compression/boost /w X octane vs a normal motor since the method of fuel injection is the main reason they are able to run such high compression with boost using standing premium unleaded gas vs a normal motor.

x2

 

[blowngt]

I ordered them from MMR they are .020 stoker pistons notched valve reliefs. mark said they were doing the math and i would have been over 10:1 but when my builder put it all together he gave me the sheet saying 9.98:1

i thought it was going to be 10.25-10.5:1 and was a little nervous about the CR with the turbos i was planning on running, until i read more into E85 and now im happy with the higher CR

I'm guessing that the reliefs help lower the compression just a bit. My pistons are true flat tops......no reliefs.

If you're running E85 I wouldn't worry to much about compression. If/when I ever rebuild, I'm going to see about going just a bit higher......like 11.0 or 11.5:1.

The throttle response and power comparision to the 17cc pistons I had before is just night and day........

 

[01bluesnake]

I ordered them from MMR they are .020 stoker pistons notched valve reliefs. mark said they were doing the math and i would have been over 10:1 but when my builder put it all together he gave me the sheet saying 9.98:1

i thought it was going to be 10.25-10.5:1 and was a little nervous about the CR with the turbos i was planning on running, until i read more into E85 and now im happy with the higher CR

You are making me worry about my comp now lol. I also ordered my pistons through MMR, but they didnt mention any change from the valve notching even though i figure it will have an effect on comp. They are suppose to be a -4cc ".030 piston on a 3.75" stroke, so not sure if they calculate the -4cc after the notching or before, but would assume after. Going to call them tomorrow to double check.

 

[04gtstang]

Even tho its a DSM a local guy here is running 10.5:1 and 45psi on E85. Car is stupid fast. He keeps pushing it harder to try and find the limits of E85. Has yet to find it.

Holy crap! That would be approaching the limit of C16 no doubt...E85 is some amazing fuel! I havnt heard of anyone hitting the point where they get knock...makes me wonder how far it can go.
Ill be going high compression for sure now when I rebuild the GT engine. Maybe 12-1...20PSI. Good combo.

 

[DaveHutch]

I just bought a teskid, 10.2:1 compression. i am putting a 2.2 kb on it, and running a return style with E85! hoping it will turn out very steady, responsive and have some good numbers on only 19 psi.

 

[Hmbre97]

Geez, I wimped out when building my motor. Wound up only going 9.3:1 with fears of E85 not being avail someday or my local station shutting down. Didn't want to be forced into running race fuel.

Now all these posts make me wish I grew a pair and put some flat tops in it. Oh well :/

 

[oldmodman]

I really envy all the lucky people that have E-85 locally available.
With only 91 octane available here in Los Angeles I will have to build an engine with "maybe 9 to 1" And even then i will be limited to 17psi at low advance or it will detonate to death.

But just as an example of how much static and boost you can run. I worked on a streamliner at Bonneville that was 14.2 to 1 static and boost that went from 15 psi in first, up to 65 psi in fifth, burning pure methanol. And after a run the outside of the intake had ice on it. We did not need to run an intercooler at all.
It was a motorcycle streamliner powered by a pair of 998cc Kawasaki 4 cylinder engines. It had over a thousand horsepower while going thought the traps at the five mile. It went 371mph.

 

[the anti-rice]

Damn...seems like Ive got the lowest at 8.5:1 Built the motor a year ago and never even thought of E85. Car isnt back together yet but we'll see how it runs.

B-headed 4V .20 over
stock cams
built bottom end
Precision T76 with a .96 a/r.

 

[corysmach1]

Im looking into doing a high comp Na nitrous build. 13:5:1 comp on E85 of course.....we will see.

 

[Mach1soldier]

Im looking into doing a high comp Na nitrous build. 13:5:1 comp on E85 of course.....we will see.

Just curious what your build plan would be and how much you intend to spray? I know you haven't started but you are the first person I have come across to mention anything even similiar to what I am in the middle of.

Here is my combo that I am piecing parts together for.

4.6 big bore block
Custom diamond 10CC dome pistons
Forged connecting rods (need to get)
GT crank
Stock heads or possibly get livernois to port them but thats a longshot.
PSRI by Todd or NASVT
Unknown cams... Either cobra intake cams or customs.
125 shot on NX wet kit, single nozzle.

Its an auto car so I'm trying to maximize power and torque from 3000-6500. Hopefully shift at 6800 or so. I'm hoping the extra compression (12.9-1) and extra cubes help increase the mid range torque for better 60 foot times.

 

[Turbo900rr]

2012 gt 11 to 1 compression, 12 psi through a d1sc procharger stage 2 intercooler on e85. no dyno numbers yet but hopefully by the end of next week.

 

[mustangcobratim]

I really envy all the lucky people that have E-85 locally available.
With only 91 octane available here in Los Angeles I will have to build an engine with "maybe 9 to 1" And even then i will be limited to 17psi at low advance or it will detonate to death.

But just as an example of how much static and boost you can run. I worked on a streamliner at Bonneville that was 14.2 to 1 static and boost that went from 15 psi in first, up to 65 psi in fifth, burning pure methanol. And after a run the outside of the intake had ice on it. We did not need to run an intercooler at all.
It was a motorcycle streamliner powered by a pair of 998cc Kawasaki 4 cylinder engines. It had over a thousand horsepower while going thought the traps at the five mile. It went 371mph.

now thats bad ass!