Tuning Questions....need help.

[kujo362]

First off, Hello everybody, new to the E85 boards, but I have lurked here a couple of years. I realize most of you are boosted, but SVT seems to be the only active board doing anything with E85, so I am looking for help. My plan is for a high compression 2V N/A build. Manley makes a +2cc domed piston that I believe if mated to the new TFS heads with 38cc combustion chambers will make somewhere around 13.5:1 give or take.

My questions are these, if the vehicle is tuned to run on E85 with that compression, and I somehow get E70 or lower, how do I keep my motor from grenading?

If I understand this correctly, this would make the tune run rich (more leaded fuel, less ethanol)? If that happens, my octane rating would fall,correct?
In other words, how do I keep stoich if I have a change in the fuel. I know stoich is not measuring octane, but octane is what I need to run this high of compression. Obviously I can't run this on pump gas, and it seems to me that the less ethanol I have, the more "pump gas" I get, effectively lowering my octane level, and then I am picking up pieces of my motor off the road.

Last question, does a FAST or BigSquirt system trim this automatically or do I fill up, check the ethanol content, then have to create a different tune, so on and so forth.

Or, is there a system out there that can do this automatically. I know there are systems that can trim boost, but what does an N/A guy do? The plan is to run E85 all the time, this is not a DD, but a weekend car.

Hopefully I made sense and didn't just show how much I really DON'T know about E85, and any help would be greatly appreciated.

Sorry for the lengthy post and thank you for any input you guys may have.

Kerry

*sorry* If it helps or makes a difference I will stay EFI.

 

[stkjock]

As to the first question - in general running E70 on a E85 tune will not harm the motor on the same tune. Yes it will run richer (there is no leaded gas in the mix BTW). I guess if you throw a ton of timing at it there is a chance of an issue, however, E85 is very resistant to detonation.

 

[kujo362]

STKJOCK,
Thanks for the reply, seems you are the only one interested. I guess I did show I know nothing about E85. I thought there was leaded gasoline in there. I thought there was 85% Ethanol and 15% gasoline. With this, I also thought that with E70 it would be 70% Ethanol and 30% gasoline, so on and so forth all the way to E10. This gave me the concern about my octane level going down. But thanks for the help.

Kerry

 

[stkjock]

Kerry

your example is correct as to the mix. but we only use unleaded now at the pumps in the US so that's why I commented on the lead.

as to octane, IIRC min pump octane for E85 blends is 100 (E70) and max is 105 (E85) however from what I know and have discussed the octane difference is not enough in general (in a ethanol application) to cause the motor to detonate.

Furthermore, being in TX you are going to see much higher ethanol blends year round. Check out this regional chart

E85 Mustangs.com - Regional Fuel Chart by state

 

[04sleeper]

First off, Hello everybody, new to the E85 boards, but I have lurked here a couple of years. I realize most of you are boosted, but SVT seems to be the only active board doing anything with E85, so I am looking for help. My plan is for a high compression 2V N/A build. Manley makes a +2cc domed piston that I believe if mated to the new TFS heads with 38cc combustion chambers will make somewhere around 13.5:1 give or take.

Sounds like a nice set up! :rockon:

My questions are these, if the vehicle is tuned to run on E85 with that compression, and I somehow get E70 or lower, how do I keep my motor from grenading?

It will be just fine. I have seen 1500+ RWHP cars run both and have no issues.

If I understand this correctly, this would make the tune run rich (more leaded fuel, less ethanol)? If that happens, my octane rating would fall,correct?

Actually believe it or not, the Octane stays the same all the way down to E50.

In other words, how do I keep stoich if I have a change in the fuel.

On most fuel injecton set up's, the stock O2 sensors will be enough for the change to the STFT's. And since E85 has a much wider "Sweet Spot" for stoich, it really makes little to no difference when switching between the blends.

I know stoich is not measuring octane, but octane is what I need to run this high of compression. Obviously I can't run this on pump gas, and it seems to me that the less ethanol I have, the more "pump gas" I get, effectively lowering my octane level, and then I am picking up pieces of my motor off the road.

You could run 15:1 compression with E70 and still be fine. The Octane does not change until you are much lower than E70. (More closer to E50)

Last question, does a FAST or BigSquirt system trim this automatically or do I fill up, check the ethanol content, then have to create a different tune, so on and so forth.

Any system with O2 sensors should change accordingly. The new FAST and Big Stuff 3 systems have Ethanol sensors and can adjust the tune as well.

Or, is there a system out there that can do this automatically. I know there are systems that can trim boost, but what does an N/A guy do? The plan is to run E85 all the time, this is not a DD, but a weekend car.

You should be just fine N/A.

Hopefully I made sense and didn't just show how much I really DON'T know about E85, and any help would be greatly appreciated.

Sorry for the lengthy post and thank you for any input you guys may have.

Kerry

*sorry* If it helps or makes a difference I will stay EFI.

Kerry,

Just tune with the stock computer and you will be fine. :thumbsup:

 

[kujo362]

You guys rock, these are exactly the answers I was looking for, thanks so much.
Unfortunately, I will have to contend with the winter blends like the rest of you guys up North. My wife is in the Air Force and right now we live in Italy. BUT, thanks to Uncle Sam, he has seen it necessary to send us to.....wait for it.......NORTH DAKOTA....yes an all expense paid trip to...from what I understand..."the tundra".

So yeah that sounds like fun.

One other question, not sure what the HP will be on this build (I don't expect much over 380 to the wheels) but do you think I can get away with the Cobra fuel hat. I know about needing the return system and injectors. But reading your posts on the pumps and hats you guys have to use to keep up with boost, I was thinking that I could get away with using the Cobra OEM tank and pumps.....what do you think?

Kerry

 

[04sleeper]

One other question, not sure what the HP will be on this build (I don't expect much over 380 to the wheels) but do you think I can get away with the Cobra fuel hat. I know about needing the return system and injectors. But reading your posts on the pumps and hats you guys have to use to keep up with boost, I was thinking that I could get away with using the Cobra OEM tank and pumps.....what do you think?

Kerry

The 03-04 Cobra fuel pumps are returnless style pumps. If you want to stay returnless they will work just fine. You may have to add a Boost-A-Pump, but you would have to try first. I think they will be enough.

 

[kujo362]

Oh yeah, no kidding, they are returnless aren't they. I am a 'tard.
Thanks for the help bradda.

 

[2FNFAST]

Its more of a ****ing ocean up here now, the missouri is flooding the shit out of us.. either way, hit me up when you get here.

 

[kujo362]

Bachmeier,
Will do man, we should be hitting Grand Forks around August 20th or so, and once we get settled, I will be up for a road trip.