Will power kill my motor or knock? Help needed deciding on E85.. - Ford Mustang Forum
 
LinkBack Thread Tools
post #1 of 14 (permalink) Old 08-10-2012 Thread Starter
Man
Rookie
 
Man's Avatar
 
Joined: Jul 2012
Location: Westminster
Posts: 16
 
Will power kill my motor or knock? Help needed deciding on E85..

'07 4.6L
Whipple HO SC, running 12psi
Detroit Rocker blower cams
Pypes LT and full exhaust (catted)
Dyno 500whp, 91 octane

I ran E85 on my prior daily driver for 4 years and am quite comfortable with safety, accessibility, etc. of E85. My experience with my car and others I've worked on tells me engines love it. My alternative is 91octane. (No 93 here)

I'd like to put my Mustang on E85, but my only reservation is that I may already be up against the max safe power. Note that my tuning strategy above 5000rpms on E85 would be very, very conservative - probably no changes other than fuel versus the 91 tune.

Assuming E85 and tune adds 50whp across the powerband, am I better off:


- Converting to E85, exceeding max safe power, but getting the benefit of 105octane, incredible knock resistance, and a little better cooling. (Concern: excess power will kill the motor before knock)

-- OR --

- Leaving as is on 91octane at safer power level but accepting greater likelihood of knock (Concern: knock will kill the motor before excess power)



'07 SGT3249 510rwhp, Whipple 12psi, Detroit Rocker cams, Pypes LT & exhaust
Man is offline  
Sponsored Links
Advertisement
 
post #2 of 14 (permalink) Old 08-10-2012
Guest
 
Back@itagain's Avatar
 
Posts: n/a
I would run the 91 tune and just make sure you purchase fuel from top tier stations. E85 does not have a true octane rating of 105. Generally it is 93 or lower. What it does have is a high latent heat of vaporization value which is where it derives its antiknock properties. Making the swap to E85 isnt always as easy as filling up the tank and getting a new tune. Depending on the current duty cycle of the fuel pump and injectors, you may need additional hardware. Also, I think it is safe to assume since you are in Colorado, E85 out there is subject to seasonal blending which each station may do differently. In the fall/winter months more gasoline is mixed to allow for easier starts and quicker warm up. Minor changes in the mix will have a big impact on your tune causing it to run rich or potentially very lean. This means constant testing before fill ups.

Having already done the fuel mixing thing for a couple years and been at a similar cross road I decided to stick with race fuel.

post #3 of 14 (permalink) Old 08-10-2012
SheizaSoSay
Guest
 
SheizaSoSay's Avatar
 
Posts: n/a
Quote:
Originally Posted by [email protected] View Post
I would run the 91 tune and just make sure you purchase fuel from top tier stations.
Don't you think it is odd that Ford Moco recommends BP fuel and they are not a top tier station according to Top Tier Gasoline.
 
post #4 of 14 (permalink) Old 08-10-2012
Guest
 
Back@itagain's Avatar
 
Posts: n/a
Quote:
Originally Posted by SheizaSoSay View Post
Don't you think it is odd that Ford Moco recommends BP fuel and they are not a top tier station according to Top Tier Gasoline.

Follow the money....thats my best guess
post #5 of 14 (permalink) Old 08-10-2012 Thread Starter
Man
Rookie
 
Man's Avatar
 
Joined: Jul 2012
Location: Westminster
Posts: 16
 
Quote:
Originally Posted by [email protected] View Post
I would run the 91 tune and just make sure you purchase fuel from top tier stations. E85 does not have a true octane rating of 105. Generally it is 93 or lower. What it does have is a high latent heat of vaporization value which is where it derives its antiknock properties. Making the swap to E85 isnt always as easy as filling up the tank and getting a new tune. Depending on the current duty cycle of the fuel pump and injectors, you may need additional hardware. Also, I think it is safe to assume since you are in Colorado, E85 out there is subject to seasonal blending which each station may do differently. In the fall/winter months more gasoline is mixed to allow for easier starts and quicker warm up. Minor changes in the mix will have a big impact on your tune causing it to run rich or potentially very lean. This means constant testing before fill ups.

Having already done the fuel mixing thing for a couple years and been at a similar cross road I decided to stick with race fuel.
Great response, man, thanks! Since I've driven on strictly E85 in my daily driver in all 4 seasons the last year I agree with a lot of what you are saying. I not only tuned my car, but logged like a mad man, had it on the dyno a bunch of times, drag raced it, etc.

First, I believe E85 is >>93octane. Closer to 100. Either way, though, we agree that it does have fantastic anti-knock properties derived from more than just octane. I don't care to argue this point though since it doesn't really affect my decision here.

Next, I agree I'll need to swap out some hardware. Injectors for sure and I think we'll wait to see what the fuel pump duty cycles look like. Currently I've got 39# and the tuner I visited today said 42# would likely suffice.

As far as the seasonal blends go, I agree that it happens but at least here it doesn't happen to the degree that is commonly believed. That said, I've never once tested E85 with a fuel tester. But I watched my fuel trims closely in my previous car and they changed very little with the changing seasons. I expected big negative trims in the winter but they only went slightly negative. In theory E85 can vary between 85% and 70% ethanol, but I believe that most of it falls between 80% +/- 3%. The car is already built to handle a 10% deviation in ethanol (E10 gas in much of the U.S., sometimes changing with season), so even if E85 did vary the full 15%, the pcm has enough fuel trim authority to deal with it.

My main reasons are safety and low to mid range torque. I sincerely believe I would have blown my previous OEM engine several times if not for E85.

What I'm considering doing is converting it to E85, but leaving it de-tuned above 4500rpms or so. That way, at high rpms I'm not making really any more power, but I have a great degree more safety. At low and mid-rpms, add extra spark to get a lot more grunt.

'07 SGT3249 510rwhp, Whipple 12psi, Detroit Rocker cams, Pypes LT & exhaust
Man is offline  
post #6 of 14 (permalink) Old 08-11-2012
Guest
 
Back@itagain's Avatar
 
Posts: n/a
Quote:
Originally Posted by Man View Post
What I'm considering doing is converting it to E85, but leaving it de-tuned above 4500rpms or so. That way, at high rpms I'm not making really any more power, but I have a great degree more safety. At low and mid-rpms, add extra spark to get a lot more grunt.
Most of the guys who I have spoke with that have lost a motor, engine builders and motors I have seen let go came at lower rpm under load....fwiw
post #7 of 14 (permalink) Old 08-13-2012 Thread Starter
Man
Rookie
 
Man's Avatar
 
Joined: Jul 2012
Location: Westminster
Posts: 16
 
Quote:
Originally Posted by [email protected] View Post
Most of the guys who I have spoke with that have lost a motor, engine builders and motors I have seen let go came at lower rpm under load....fwiw
Good to know. I was a little uneasy about my assumption that failures happen around peak power whp. I wonder if peak torque is more of a stressor than peak whp.

'07 SGT3249 510rwhp, Whipple 12psi, Detroit Rocker cams, Pypes LT & exhaust
Man is offline  
post #8 of 14 (permalink) Old 08-14-2012
Apprentice
 
flounderlipps's Avatar
 
Joined: Aug 2006
Location: Uranus
Posts: 137
 
I would not run 500 whp on 91 octane.Your asking for trouble
flounderlipps is offline  
post #9 of 14 (permalink) Old 08-15-2012
Guest
 
Back@itagain's Avatar
 
Posts: n/a
Quote:
Originally Posted by flounderlipps View Post
I would not run 500 whp on 91 octane.Your asking for trouble
I run 630rwhp on 93 so 500 on 91 should be doable. I probably wouldn't try it on a returnless fuel system and would trust very few tuners to be able to pull it off. With that said, one man's 500 Dyno is another's 450.
post #10 of 14 (permalink) Old 08-15-2012 Thread Starter
Man
Rookie
 
Man's Avatar
 
Joined: Jul 2012
Location: Westminster
Posts: 16
 
Quote:
Originally Posted by flounderlipps View Post
I would not run 500 whp on 91 octane.Your asking for trouble
I agree. Stock 4.6L being pushed by 12psi Whipple HO SC with cams and exhaust. FWIW, I'm at 5400' altitude where Patm=12.1 rather than 14.7 near sea level. So my engine "feels" like it is getting ~10psi pushed rather than 12psi. Either way, I think high boost + high temps + 91oct isn't the friendliest combo for the engine.

'07 SGT3249 510rwhp, Whipple 12psi, Detroit Rocker cams, Pypes LT & exhaust
Man is offline  
post #11 of 14 (permalink) Old 08-15-2012 Thread Starter
Man
Rookie
 
Man's Avatar
 
Joined: Jul 2012
Location: Westminster
Posts: 16
 
I am still getting the hang of datalogging in this car and wanted to go out and assess the approxiamate size of fuel injectors I'll need for E85. I'm running 39# now and thinking 60# will work for me, maybe 80#.

Anyhow, I didn't get a great datalog as I forgot to log rpms and couldn't figure out what to log to assess injector duty cycle.

But I found something I didn't like... in my 3rd gear pull my fuel pump duty cycle gets pegged at 0.5 with around 2 seconds remaining in my pull (maybe 5000rpms or so). That means my fuel pumps are maxxed out as is on 91oct, right? And I'll definitely need new fuel pumps to go to E85...

beeez.com/shelby/3rdgearpull.csv

If anyone wants to check out that log (see time 138 seconds) to confirm my suspicions, I'd appreciate it. And how can I log injector duty cycle? (Anyone got a nice DLF file they want to send me??)

'07 SGT3249 510rwhp, Whipple 12psi, Detroit Rocker cams, Pypes LT & exhaust
Man is offline  
PONY Member
4.6L Member
S197 Member
 
jrglenni's Avatar
 
Joined: Mar 2008
Location: Boston
Posts: 666
 
I would go with the E85 and leave it detuned as you say. Your combo right now probably puts you at a good chance of knock, and the E85 would remove that worry. The additional cooling from it would be beneficial as well.

Keep in mind though that since you are running a PD blower, your TQ should be pretty close to peak even at low RPMs. There might not be much room to safely add power even down low. I'd still make the switch even if it meant that I wouldn't add power, the other safety benefits are enough to justify it.

Power in Numbers: None of us are as dumb as all of us
jrglenni is offline  
post #13 of 14 (permalink) Old 08-16-2012 Thread Starter
Man
Rookie
 
Man's Avatar
 
Joined: Jul 2012
Location: Westminster
Posts: 16
 
Thanks for the replies so far. I'm definitely going E85. Among these choices, what would you do?

a) 12psi, detuned E85
b) 9psi, optimized E85
c) 12psi, optimized E85 low and mid range with detuned high end

I'm leaning towards choice B as it seems like the best blend of safety and power. Additionally, I could swap on the 12psi pulley for the strip. The one thing that concerns me is that I don't want a step down in power from my current 12psi 91oct tune and option B might be the only one of those 3 options that could make less power than I currently have.

'07 SGT3249 510rwhp, Whipple 12psi, Detroit Rocker cams, Pypes LT & exhaust
Man is offline  
post #14 of 14 (permalink) Old 08-16-2012 Thread Starter
Man
Rookie
 
Man's Avatar
 
Joined: Jul 2012
Location: Westminster
Posts: 16
 
Also, note that my Patm at high altitude = 12.1, where it is around 14.7 at sea level... so my engine boosted by 12psi "feels" the same pressure a sea level engine boosted by 9.5psi. So my boost, at least to the engine, isn't as high as it seems.

'07 SGT3249 510rwhp, Whipple 12psi, Detroit Rocker cams, Pypes LT & exhaust
Man is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Ford Mustang Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a VALID email address for yourself, otherwise you will not receive the necessary confirmation email needed to confirm, validate and activate your new AFM member account.

Failure to provide a VALID email address, will result in the cancellation of your new AFM member account registration.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome
 


Search Engine Friendly URLs by vBSEO 3.6.1