Importance of Accuracy in e85 Mixes

Duey1083

Duey1083

Greenie N00B Member
Greenie Member
Hey everyone!

Brand new to these threads and the idea of being tuned for an e30 mix. I drive a 2011 MS3 with 122,000 miles on it (2nd owner since 2013 and 13,985 miles). Checked the compression this winter and all looked good (also had leakdown test done a couple years ago and it was <5% if I recall correctly).

I have HPFP internals, 3" widepath JBR intake, COBB APv3, and an eBay test pipe on the way. I will be tuned by Stratified (being a Canuck ) and I think they nearly have me convinced to be tuned for just 91 pump and a second map for e30 mix.

My question pertains to importance of the accuracy of the mix. I think it is best to err on the higher side of ethanol (I.e. tuned for 30, better to put 30%+ in the tank), with consideration to never exceed a 50/50 mix. Reason I ask is because our 91 pump gas in Canada says contains up to 10% ethanol, and based on my reading e85 can be anywhere between 70% - 90% based on the season.

Would it be reasonable to assume 91 pump at 5% and e85 at 75-80% ethanol content and base my calculations on those assumptions? Without a fuel testing kit (and what a pain that would be at the pumps everytime), not sure what my best course of action would be.

Also, I'm only considering running the e30 during summer and switching to 91 during the winter.

Thank you in advance!

Andrew
 
Its really not that serious, especially on a DI car. Even if you are off +/-5% on a e30 mix you're not likely to knock on any of the tuners maps. Try to get it as close as possible to target during the tune though, just to get the mafcal good and accurate.
 
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Get a test kit and check the E content a few times and see how consistent it is. If it's consistent, then you can calculate it pretty easily. Double check in the winter time to make sure it doesn't change or what the winter blend is.

And/or run an ethanol content sensor. Takes a lot of the guesswork out of it. Feels like cheap insurance for me when running E blends. I use the Fuel-it kit/module and I can check E content on a phone app.

Genpu has WOT fueling correction, so yeah get it pretty close and call it good. I always target like 5 percent more than what it's tuned for, for a little extra knock protection and keep it conservative. With closed loop fueling, it will account for the minor difference and won't run lean or anything.
 
Thank you for the replies!

I purchased the Briggs & Stratton test kit off Amazon...it was the cheapest available, but is still glass and should be good enough to tell me roughly what the percentage of ethanol is. It didn't have all the graduations from 0% to 100%, but it also won't cost me $50 CDN for a glass tube, haha.

@aaronc7 can you send me some photos of how you installed that Fuel It ethanol sensor?

I apologize for the newbie question, but how long have you been running ethanol and has there been any damage to your lpfp, hpfp, or fuel lines? I've read that anything under 50/50 should be safe, and I'll be far below that, but that's all anecdotal. Just curious about level of risk to cause damage long term.
 
Duey1083 said:
Thank you for the replies!

I purchased the Briggs & Stratton test kit off Amazon...it was the cheapest available, but is still glass and should be good enough to tell me roughly what the percentage of ethanol is. It didn't have all the graduations from 0% to 100%, but it also won't cost me $50 CDN for a glass tube, haha.

@aaronc7 can you send me some photos of how you installed that Fuel It ethanol sensor?

I apologize for the newbie question, but how long have you been running ethanol and has there been any damage to your lpfp, hpfp, or fuel lines? I've read that anything under 50/50 should be safe, and I'll be far below that, but that's all anecdotal. Just curious about level of risk to cause damage long term.
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No damage if you're running under 50%. I've been on E33 for like 3 years straight and I haven't cleaned my HPFP, but it's spotless. You'll be fine.
 
Couple things here:

1. You will still get black death over time, depending entirely on the oil and fuels you use. Yes, this includes just straight up 91.
2. If you're going to ride the line between knock proof and not, then it absolutely matters what % ethanol you're using, and you should stay on top of this.
3. It would be wise to pick up one of those flex fuel bluetooth sensors like a couple people have so you can check your eth% with your phone. It will be too late to change anything by the time you get a solid read, but at least you'll know not to beat on it if your % is too low or high, and you can fix it 1/4 tank later.
 
Duey1083 said:
Thank you for the replies!

I purchased the Briggs & Stratton test kit off Amazon...it was the cheapest available, but is still glass and should be good enough to tell me roughly what the percentage of ethanol is. It didn't have all the graduations from 0% to 100%, but it also won't cost me $50 CDN for a glass tube, haha.

@aaronc7 can you send me some photos of how you installed that Fuel It ethanol sensor?

I apologize for the newbie question, but how long have you been running ethanol and has there been any damage to your lpfp, hpfp, or fuel lines? I've read that anything under 50/50 should be safe, and I'll be far below that, but that's all anecdotal. Just curious about level of risk to cause damage long term.
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https://mazdaspeeds.org/index.php?threads/diy-ethanol-content-gauge.5185/page-2

Good post by Johnny tightlips ok where to put it online on the feed line.

The Briggs and Stratton one is ok but hard to get accurate due to small size and larger diameter. I bought it too. What I have now and like a lot is the fuel it one. If you're gonna get a sensor though, save your money and don't buy the nicer test kit.
 
https://www.fuel-it.com/bluetooth-flex-fuel-analyzer/

BT module is $200, you can find a sensor for around $50, or pay them $100 for one. You'll need the GM pigtail too for basic wiring. I ran my power wire to the fuel pump fuse. I mean all in all you're looking at around or little over $300..... but the BT function makes it easy.

If you dont mind a permanent gauge, the innovate ethanol sensor kit is about $180 which includes sensor and gauge etc.

Innovate Motorsports 3904 MTX-D Dual Gauge Kit -Ethanol/Fuel Temp, 1 Pack
 
Thank you all for the very helpful suggestions!

I've reached out to my tuner to find out more information from them on the knock sensitivity of their e30 tunes.

@aaronc7, sorry to bother you again...I went through that thread, and while @JohnnyTightlips proposed a possible fuel fittings setup for the ethanol sensor for the stock fuel lines in our cars, I couldn't see if anyone actually implemented or tested it.

It was late when I read it, so I'll go through the thread again.
 
Knock comes in somewhere between e25 and e30 depending on what the e85 is cut with, etc. I run e35 for simplicity of mixing (1:2 mix per quarter tank for me) and extra security if I get a bad batch.
 
Duey1083 said:
Thank you all for the very helpful suggestions!

I've reached out to my tuner to find out more information from them on the knock sensitivity of their e30 tunes.

@aaronc7, sorry to bother you again...I went through that thread, and while @JohnnyTightlips proposed a possible fuel fittings setup for the ethanol sensor for the stock fuel lines in our cars, I couldn't see if anyone actually implemented or tested it.

It was late when I read it, so I'll go through the thread again.
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Sorry I don't even have a speed anymore, but you could pretty easily cobble together something using straight or 90* quick connect fittings and some fuel line. I don't think anyone has a concise DIY guide on here unfortunately. Talking to the guys today, the factory quick connects at the hard line to the tank and hpfp connection is 5/16". I believe the ethanol sensors are 3/8". You could use either 3/8 or 5/16" line depending on what barb size you get for the quick connect fittings.

Just an example, they have a huge lineup in all sizes: Dorman 800-080 Fuel Line Quick Connector for 5/16 In. Steel to 5/16 In. Nylon Tubing, Pack of 2

Hose: http://www.radiumauto.com/Vapor-Shield-Fuel-Hose-P1097.aspx
 
I had the same mods as you (plus a tmic) and was tuned on e30 (or whatever a 1 gal e85 to 2 gal 93 ratio comes to). Once I guessed wrong at tank capacity remaining and had an at least an extra gallon of E in the tank. Ltft went up a few percent but nothing beyond that. Try to get it close, don't math wrong, and you should be ok.

I really doubt stratified is going to run you on the edge of knock on the k04. that's hard to do in the first place with anything over like e20 and you'd likely be beyond the safe torque limit of the motor.
 
Thank you @mangosmoothie, I appreciate the vote of confidence. I'm still waiting to hear back from Stratified on this, but I'm quite certain you'd be right.

I might explore the idea of building an ethanol sensor because it sounds like a fun project, but I'll not wait before trying e30 for my car.

On a side note, would you recommend upgrading the TMIC with the k04 or is it not worth it until I switch to something like the BNR S3 (if that day comes). In guessing a downpipe would be a much better upgrade before the TMIC?
 
Intercooler upgrade is more beneficial at this point IMO. Doing pulls on a heatsoaked intercooler in the dead of summer is no good
 
I agree with sho. the stock downpipe isn't a as big of a restriction as some people think. Stratified, Freektune, Nishan, and Purple Drank have all posted cars cracking 300 whp on good pump gas (no ethanol) with the stock dp.

I made 350 whp with the CST4 on an e mix with the stock dp. Sure, probably could have made 360-370 with a downpipe but whatever. I had too much power for the stock suspension and all seasons anyway.

Even in the balls of summer on e30 I didn't see kr with my tmic and k04. But the difference between heat soaked bats and ambient temp bats feels huge. I'm sure you've noticed how doggy the car feels when it's heat soaked, even stock.
 
Absolutely I have...feels like Jekyl and Hyde sometimes. The car pulls like a raging lunatic one day and the next it feels lethargic.

I was dreading the downpipe install out of fear of breaking turbo studs. I will consider it if the K04 eats it and I upgrade to the S3, assuming my car doesnt rust away :(

This is great information...glad I signed up to this forum. This is the first time I've heard that the DP isn't as restrictive as advertised and that you can still make great power.

I dont have any super lofty goals as it is still my DD, so if I can break 300 whp on e30 with the stock k04, that is money to my ears!
 
Well, the time is nearly upon me to try and max out my k04 with an e30 blend. I've installed all of my supporting mods and have received my e30 tune. Just waiting to rundown the tank of fuel I currently have.

Quick question for those of you who live an inconvenient distance from an e85 station. When you fuel up, do you bring some gas cans with you to also fill up to bring with you to a regular gas station? How do you go about filling up at a gas station without e85...proceed first with filling with e85 from the gas can and then top-up with 91 to blend down to e30?

I would feel so strange doing that...people might think I'm a nut...why is that guy filling his car with a gas can when he's at a pump? o_O

This is just a logistics ask...
 
I plan out my fuel stops, and park between a regular and a corn pump so I don't have to move the car. I also tend to fill up at 1/4 tank just in case.
 
@Enki, unfortunately there is only one e85 station in my city. It's nice and close to my work, but with Covid, I'm working from home and don't drive too much.

So in order to ensure that it's not a complete nightmare to deal with, I'd likely fill the car with e85 along with a couple or few 5.3 gallon gas cans that I could then use at regular fueling stations.

I do have a gas station less than 2 blocks away from me, so I could just do a partial fill there and limp my car home carefully (out of boost) and top up with e85 in my garage. The tuner said I should be safe like that.
 
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