Ok so my 10:1 build is alot more knock limited than I thought. At 10psi Im already around 3degrees BTDC. I am running RC 550cc injectros and wanted to know if I could run E85 I read accouple forums where people have done so but not exactly sure. So my question is should I retard the spark and run 15 psi or will I be better off stuck at 10psi with E85?

That is up to you, your tuning skills, E85 availability, and a host of other variables.

HAHA Dave we both know the answer about my tunning skills.No, I have learned alot with ms and started to undertand it. I have not found a dirrect answer if running spark atdc has any ill effects and will it still create more power.

Can RC550's even support enough fuel for 10 or 15psi?
Anyways...You wont be making power with spark atdc. Do you get knock at 3degrees btdc?

Originally posted by Gruff511
Can RC550's even support enough fuel for 10 or 15psi? Anyways...You wont be making power with spark atdc. Do you get knock at 3degrees btdc?

10 or 15 psi is not a measure of power. This has been covered over and over.

The fuel consumption is based on air density, not pressure level, as each turbo flows a different mass of air at the same pressure ratios.

Originally posted by CODE4

Originally posted by Gruff511 Can RC550's even support enough fuel for 10 or 15psi? Anyways...You wont be making power with spark atdc. Do you get knock at 3degrees btdc?

10 or 15 psi is not a measure of power. This has been covered over and over. The fuel consumption is based on air density, not pressure level, as each turbo flows a different mass of air at the same pressure ratios.

I know its not a measure of power. I wasn't asking a general question. Sorry if I worded that wrong, it was to the OP, I don't know what his setup is so I guess I should of asked, ''what are you injector duty cycle at, at 10psi with e85?''

No, I do not knock at 3 degrees I might be able to sligtly increase but havent had the chance to. So I played it safe till I can better adjust. Also why wouldnt spark atdc make any power? Would it still help push the piston down even though its alil after the power stroke. Something moderate like 5 degrees ATDC.

any ignition event must occur BTDC. The flame front takes time to propagate and make power. If the ignition event occurs after the piston has already reached 0*, you are not going to gain any power.

You will also have a super high EGTs from igniting the mixture so late. How are you monitoring knock? Are you sure you are in fact getting knock? What plugs are you running, maybe try a colder plug

Originally posted by CODE4
any ignition event must occur BTDC. The flame front takes time to propagate and make power. If the ignition event occurs after the piston has already reached 0*, you are not going to gain any power.

Thanks for clarifying that.

Originally posted by SilvrEclips
You will also have a super high EGTs from igniting the mixture so late. How are you monitoring knock? Are you sure you are in fact getting knock? What plugs are you running, maybe try a colder plug

By ear. Im sure its knock because when I back it up 3 degrees it goes away. Also knock has that distinct rattle can sound. I am running BKR7E and from what I can see the only step colder with that style plug are iridium plugs.Another thing is that my IAT is around 108 degrees,which isnt helping out. I have E85 station about 5 miles away, im thinking of doing a 50/50 mix with 93 octane. Then monitor duty cycles and pulse widths.

Thats not true, you just need to get a hold of an 8 series plug. Bkr8e or something like that. Im not sure if the parts store will stock these plugs or not. I would also not recommend listening for detonation by ear, its very dangerous and most of the time you are knocking pretty bad by the time you hear it. I would at the very least make a det can setup. This is what I tune by and it works very well.

I am in the process of making a det can. Ok so I had no clue how much rerouting the compressor inlet would make. I routed just like the aem cold air intake. At idle or a light temps go up to a max of 99 degrees. At WOT my temps reaches maximum of 87 degrees. I am looking into finding a colder plug and into those PTFE gaskets to further lower my IAT.

108F is not high enough to cause issues. I have seem some people hit around 200F intake temps and not have any issues. May not be able to run as much timing but doesnt cause much knock. I think you might have something else going on here.

So I got went to gas station and filled up with straight e85, no mixing. I let ve adjust the tables abit. Noticed fuel pressure dropped to 40psi, so I raised it to 45psi. After abit of crusing I started raising spark. I havent done any crazy pulls but I datalogged some driving.


MSQ:
http://www.2shared.com/file/TYKqIXwy/Cabrito_E85.html



Datalog:
http://www.2shared.com/file/2ZRYstF0/e85_re.html