What Is The In Cylinder IAT Drop With e85?

[Department Of Boost]

I just spent the last hour and a half searching high and low for a concrete answer to this and I’m pretty surprised, I came up with nothing that makes me all warm and fuzzy.

I’m getting closer and closer to jumping on the e85 bandwagon, but there is a piece of the puzzle that I would like an answer too. And that is how much does e85 lower your IAT’s?

The way our IAT sensors are set up we can’t get a true reading of how much e85 drops our IAT’s. Our IAT sensors are before where the e85 is injected, so they don’t read that temp reduction.

I’m about to jump on the e85 thing for all of its advantages. But the number one advantage that has me sold is the reduction in IAT’s and my ability to raise the threshold where the ECU starts pulling timing. For example:

Right now my blue car starts pulling timing in my 93 tune at 136deg IAT, which doesn’t take long to get too, especially when it is hot out. But, lets say that e85 reduces IAT’s by 100deg (I think it’s higher though). If that were the case I could set the threshold where the ECU starts pulling timing at 236deg and have the same safety margin I have now because in theory a 236deg IAT with e85 added too it is 136deg. And therefore safe.

Does that logic track?

Of course there are all the other advantages to running e85. More timing, more boost and therefore more power. Which I will be more than happy to take advantage of. But what I really want is for the car to make the same power heat soaked on a 90deg day as it does in a controlled environment like the dyno cell.

What I am looking for is having all of my power, all of the time.

But to set the tune up to do this I need to know how much the e85 drops the IAT’s after the IAT sensor so the “correction factor” can be built into the tune.

Anyone have this data? I google’d my tail off and only came up with half answers. Some of these “half answers” are below with links to the source material.

Thanks for your help!



Reference #1
A paper written by a MIT student in 2010.

The data:
The knock limit for e85 is shown as being at a IAT 110deg C (230deg F) higher than gas.

Section 6.1.2 Peak Cylinder Pressure

http://dspace.mit.edu/bitstream/handle/1721.1/59952/676953430.pdf

Reference #2
E85 calculator

Maybe someone smarter than me can figure this worksheet out. I’m getting a IAT drop of 253deg F. That seems high, but not far off the results from the first reference.

http://www.pcmforless.com/index.php?option=com_content&view=article&id=57:e85-calculator&catid=34:tuning&Itemid=56

Reference #3
Fast Forward Superchargers Forum
16th post

Another fact is that the latent heat of E85 in the correct AF ratio compared to gasoline is four times as great. This means four times the temperature drop. Since gasoline at a 12:1 AF ratio will drop the air temp about 50 deg F, this means that E85 at the corresponding lambda for E85 , would drop the air temp about 200 deg... or an additional 150 deg F temp drop. FWIW, that is about as good as an Air/Air IC running 15psi of boost with the MP62...

http://www.fastforwardsuperchargers.com/forum/archive/index.php/t-1934.html

 

[weather man]

Old post I found on lightningrodder,com. He did not update. Seems applicable, if a little hard to understand.

12-01-2009, 01:19 PM #1 03birdsong
Member

Join Date: Nov 2009
Posts: 53
Rep Power: 3283681

freezing the intake charge with no nitrous or killer chiller...
i switched my truck over to e85 and in the process i baught a nitrous fuel solenoid lines, and dryshot nozzle to constantly spray e85 over the blower to help cool it. little did i know how cool it would actually get. it dropped the intake plunum to 49 (normally 170)degrees no matter how many pulls i threw at it and the blower stayed at 150degrees (normally 200-210) pull after pull. even at stop lights or jest letting it idle the intake stayed at 49 degrees and blower actually stayed around 130. im running a 2.80 upper and a 6lb lower so the blower got pretty hot. now i am switching over to a 10lb and reporting my blower to the max, to try and reach my 600whp goal with an eaton(no nitrous)

just tap into ur fuel rail with the ford fuel pressure fitting, run up to the fuel solenoid wired with a standard on or off switch. run the out side of the fuel solenoid to a cheap ebay fuel pressure regulator so u can regulate the idle spray...and tap into the plenum on the bottom side behind the throttle body. im using a .014 size jet with e85. and i have the pressure at the jet regulated to 25psi and apon wot its max pressure at the rails.

then u should be able to run more boost and more timing!!!

Last edited by 03birdsong; 12-01-2009 at 01:21 PM.

 

[Department Of Boost]

Old post I found on lightningrodder,com. He did not update. Seems applicable, if a little hard to understand.

12-01-2009, 01:19 PM #1 03birdsong
Member

Join Date: Nov 2009
Posts: 53
Rep Power: 3283681

freezing the intake charge with no nitrous or killer chiller...
i switched my truck over to e85 and in the process i baught a nitrous fuel solenoid lines, and dryshot nozzle to constantly spray e85 over the blower to help cool it. little did i know how cool it would actually get. it dropped the intake plunum to 49 (normally 170)degrees no matter how many pulls i threw at it and the blower stayed at 150degrees (normally 200-210) pull after pull. even at stop lights or jest letting it idle the intake stayed at 49 degrees and blower actually stayed around 130. im running a 2.80 upper and a 6lb lower so the blower got pretty hot. now i am switching over to a 10lb and reporting my blower to the max, to try and reach my 600whp goal with an eaton(no nitrous)

just tap into ur fuel rail with the ford fuel pressure fitting, run up to the fuel solenoid wired with a standard on or off switch. run the out side of the fuel solenoid to a cheap ebay fuel pressure regulator so u can regulate the idle spray...and tap into the plenum on the bottom side behind the throttle body. im using a .014 size jet with e85. and i have the pressure at the jet regulated to 25psi and apon wot its max pressure at the rails.

then u should be able to run more boost and more timing!!!

Last edited by 03birdsong; 12-01-2009 at 01:21 PM.

Well its helpful in that it backs up that e85 cools things down. But if I’m going to raise my IAT threshold for pulling timing I’ll need something a lot more focused than that.

Thanks though

 

[BruceH]

Contact Marc S. He has a friend in Arizona who runs e85 with a whipple and without an intercooler because it drops temps so well. I can't remember the guys name, I know he is a member here but I don't think he's very active. IIRC he was experiencing his coolant temps dropping due to the e85.

If nothing else just keep the spark retard as is until you get a feel for what the fuel is doing. I doubt that you will be able to find a detonation point. One of the papers I read stated that there was no increase in detonation resistance past 50% ethanol and I'm pretty sure they couldn't get it to detonate. I know I haven't been able to but I realize you are road racing which will really put everything to the test.

Have the e85 plans been sped up?

 

[CPRsm]

It's going to be hard to raise the threshold w ait's you can't really measure. EFI just doesn't pull out heat as much becase the injectors are close to the valve. It doesn't have the time to pull the heat out like mechanical injection or a carb. So I'm not so sure about his spreadsheet. "X" amount of fuel does not equal a given heat reduction in aits. If you mount the sensor in the intake, that may be the closet thing you are going to find to an accurate ait reading. Compare before and after intake temps and you can probably subract that from your threahold.

 

[dysan]

For now Lito has raised my limit to 170 from the normal 130 he used to use. What I do eventually want to do is get one or two EGT sensors and do testing with 93 octane fuel and then E85 to see the actual exhaust temp differences.

I am hoping the EGT sensors will reflect the extra cooling when using E85 compared to gasoline but I could be completely wrong in my thought.

 

[TurboX]

For now Lito has raised my limit to 170 from the normal 130 he used to use. What I do eventually want to do is get one or two EGT sensors and do testing with 93 octane fuel and then E85 to see the actual exhaust temp differences.

I am hoping the EGT sensors will reflect the extra cooling when using E85 compared to gasoline but I could be completely wrong in my thought.

Arent EGTs a measurement of AF and not necessarily charge temps ?

 

[19COBRA93]

EGT's are going to be considerably cooler with E85 because it burns cooler. It's not because of any cooling effect it has on the intake air charge. It's impossible to measure cylinder temp before combustion, and like mentioned on a FI setup the cooling effect of E85 on the air charge will be minimal. Regardless, the cylinder temps when running E85 will be much cooler when compared with gasoline.

 

[stkjock]

IIRC EGTs and combustion temps on E85 are 200-300* cooler

 

[weather man]

This might be what you are looking for.

http://www-personal.umich.edu/~annastef/papers_FFV/Oliverio_SAE_2009-01-0657.pdf


EDIT: I read it all. Some heavy lifting, but a few nuggets in there.

 

[BruceH]

For now Lito has raised my limit to 170 from the normal 130 he used to use. What I do eventually want to do is get one or two EGT sensors and do testing with 93 octane fuel and then E85 to see the actual exhaust temp differences.

I am hoping the EGT sensors will reflect the extra cooling when using E85 compared to gasoline but I could be completely wrong in my thought.

Have you looked at what the rear o2 sensors are giving you for temp readings? They are the sensors that the ecu uses for cat and exhaust valve protection. I can tell you they are a few hundred degrees cooler with e85.

 

[weather man]

A little more digging. The bottom pic, I think, really shows why E85 prevents detonation, a very homogeneous charge. Pulled the charts from:

http://www.ars.usda.gov/SP2UserFiles/Program/213/Teleseminars/Robert%20Stein%20(AVL)%203-29-11.pdf

 

[dysan]

Have you looked at what the rear o2 sensors are giving you for temp readings? They are the sensors that the ecu uses for cat and exhaust valve protection. I can tell you they are a few hundred degrees cooler with e85.

Haven't because I don't have my rear o2's in the car except when I have to get inspected at which point I put catted pipes on the car.