E85Forum.com

jmanley · Joined: 23 Jun 2009 Posts: 13 Location: Fargo, ND

So, when I ran on gas, I was getting readings with my MAP sensor showing at WOT and higher RPM's (above 4000 rpm) around 98, which is very good and efficient.

Switched to E85, and now I'm seeing MAP readings at 90 at WOT, rather than about 98 like it was before.

Nothing else has been changed that should affect that.

Any thoughts?

hotrod · Joined: 19 Apr 2005 Posts: 872 Location: Colorado

Give us a clue what kind of car/engine this is and the units of measure --- 90 what?

pounds per sq inch, kg/cm^2, cubic feet per second, cubic meters per second, grams per second, lbs per minute, slugs per fortnight??

Larry

jmanley · Joined: 23 Jun 2009 Posts: 13 Location: Fargo, ND

Slugs per fortnight....I needed a laugh tonight! Thanks! Smile

That was great!

1972 Mustang Mach 1, 351c stroked to 408 cu in, just over 11:1 compression, fuel injected (Accel Gen 7 EFI).

The 90/98 numbers are KPa

Alcohol · Joined: 17 Apr 2007 Posts: 634 Location: Central Wisconsin

What else can you share jmanley?

Do you measure EGT?, AFR via O2 sensor?

How is performance at WOT?

How do the plugs each look?

Is this a bracket car or a mean street machine Very Happy

Timeslips now vs gasoline?

I am curious about the slug consumption per fortnight also Laughing

It has been shown that excessive slug consumption can foul the throttle body you know.

I take it you are comfortable that you are delivering enough fuel?

jmanley · Joined: 23 Jun 2009 Posts: 13 Location: Fargo, ND

Don't know EGT, but AFR I do have. I'm running .83 lambda at WOT at peak torque, .87 lambda at WOT both before and after peak torque. I was running it about 4-8% rich and letting the computer pull out the extra fuel.

Performance is good. I didn't see any HP gains via the switch from 104 octane race fuel to E85, but it was consistent. Seemed my 60' times were a bit better, but my #'s say I was running the same HP numbers as race gas, so my assumption is that it's laying off somewhere else slightly.

This is a bracket car - didn't get to check the plugs last weekend, but hoping to this Saturday.

Oh, and I also didn't really see any major cooling with E85 like I've read others talk about.

Alcohol · Joined: 17 Apr 2007 Posts: 634 Location: Central Wisconsin

I'll let others more knowledgeable about this kick in comments but I am wondering what you did with injector sizing (as compared to gas), timing, and if you played with pulse time on the injectors?

The cooling effect is far more noticeable with carbs and where only water restriction or no thermostat is run (then gettting enough heat to at least hit what seems to be the minimum of 160-170 for start and 175-185 for end can be a challenge).

jmanley · Joined: 23 Jun 2009 Posts: 13 Location: Fargo, ND

I changed the injectors from 40# to 60#, upped the fuel pressure slightly from 43# to 50#, did NOT adjust timing, but did have to change pulse timing (base fuel map) to get the mix right.

Ahhh, ok. I'm running a thermostat.

Alcohol · Joined: 17 Apr 2007 Posts: 634 Location: Central Wisconsin

This is just a wild hair thought here- so dont take it too seriously Laughing

This link goes to cam discussion in an extreme application with methanol (more fuel, more exhaust, etc). Yet- is this somewhat true with E85 which also has more exhaust gas than gasoline? (not extreme like methanol though). What if you are not letting all exhaust out- wouldn't your intake manifold vacumm also drop at that point because you cannot let her breathe? (same effect may come from headers/exhaust).

http://www.dragraceresults.com/article.cfm?id=2455

Please note that there is not much info out there on all alcohol's exhaust volumes- as noted in the link- only assumptions. I did have a former Chrysler fuels engineer who did nearly 20 years study with alcohol fuels leading to the FFV tell me about this issue but I never asked for his documentation.

jmanley · Joined: 23 Jun 2009 Posts: 13 Location: Fargo, ND

Ok, guys....is my face red. Sad

I was logging MAP %, then putting it on a MAP KPa chart. The numbers don't mesh, and therefore it was showing me the error I described.

When I recorded CORRECTLY MAP KPa and put it on the MAP KPa chart, it was showing 99.2, which is VERY good and efficient.

Problem solved. Thanks for all the "brain dump" thinking you all did to help!

Jay

Just shows - sometimes it's not nature, it's the dummy behind the computer. Smile

Alcohol · Joined: 17 Apr 2007 Posts: 634 Location: Central Wisconsin

It is just the slugs jmanley Laughing

Thanks for the followup- always good to solve a mystery Wink