SPDKLZ1

I'm looking to gain some extra hp/tq and have 4-5 months to think about before I'll be driving the car again. I have The BTR stage 2 cam with the main supporting mods and AHP ported heads on 91 octane, no mill. E85 is readily available at multiple gas stations around my area. For the E85 guys, what would be the recommended compression ratio to reap the benefits of E85? What kind of increase in hp/tq could I expect to see? Eventually I'd like to get my hands on a Mamo top end package but curious about E85 in the meantime.

MTPZ06

E85 shines with high compression. Grab the D Steck flex fuel kit, mill your heads .030, and go to a .040 head gasket (OE is .054). That way, when you go to Mamo heads, your OE heads with a .030 mill will still appeal to a wide audience if you're looking to sell them.

Whis9

What brand gasket do you recommend?

jayyyw

Cometic

jayyyw

Depends on how crazy you want to get. Do you still want to be able to run pump gas?

I did a .050" mill, which is around 12.3:1. I, now, want to go over 13:1.

I agree with MTPZ06. .030" mill with a .040" Cometic head gasket will get you right at 12:1.

Most of the gains with e85 will be in the mid-range.

SPDKLZ1

I would like to be able to fall back on 91 if I had to but I don't think I could take .030 off the heads then. E85 is all over the place so I shouldn't need to switch to 91. I think I'd like to keep it 12:1 or less. Thanks guys.

nuke61

What Joe Cordes (CPR in Phoenix) explained to me, because I have an 0.030 mill, is that how his tuner (NicD) and Joe handle it is by:

• putting in straight 91 octane and tuning to that
• draining out the 91 and putting in E85 and tuning to that
• blending the timing table results

Then, apparently, you can put in anything from 91 to E85, and the timing is automatically adjusted for maximum horsepower. This is how I understand it be, but if I got it wrong, I'm sure someone will correct my interpretation of what Joe told me.

Basically, the best of all worlds, whether you have 91, E85, or some mixture of both - the Steck conversion figures out the octane and feeds the ECU.

MikeOC

The problem with FlexFuel or in your case, keeping the stock castings resellable for gas, is that CRs that work for both are shitty compromises for both fuels. Too high for gas is still too low for E85. E85 is plentiful where I live and I regretted having a FlexFuel CR. If I were staying stock parts and going E85, I'd shoot for 13.5-13.8. Wasting your time and money otherwise. Just my opinion.

MTPZ06

Jesse, you can reach out to AZDave (unless he chimes in here), but he runs 91 on the street with .030 milled heads, but mixes in higher octane fuel for his race events.

jayyyw

The one thing you do have to be careful with is going to be your Dynamic Compression Ratio, which is dictated by your camshaft. I'd call up BTR and chat with them about it. Give them a few SCR numbers you want to target and find out what the DCR would be. For 91 octane, you want to stay closer to an 8:1 DCR.

American Heritage

You will start seeing worthwhile gains from E85 @ 11.5 but optimal for E85 only (no 91/93) is 13.5-14.1

http://www.americanheritageperformance.com/

Unreal

Nuke is correct. 30 mill on 91 just takes 2-3 less timing. Still makes more power and then when you add ethanol timing ramps up for a nice power gain.

redcycle13

I'm running 12.4 with my Mamo combo. It makes good power on 93 octane (600+), and did well on E85 too (630+). The compression ratio was chosen as a compromise between the two fuels to allow me to get by with 93. Probably would have made more power on 93 with slightly less compression, but then the E85 would have suffered as well. Like I said it was compromise so the car could be filled up anywhere premium fuel or E85 is available. I have had no issues traveling with the car outside of my local area where E85 is available.

lt1z

Over 12:1 shines on E85.

Lorenzo Serra

That's a very interesting topic!

How can a 12:1 CR be reached on stock casting? Will 0.30 milling and .40 cometic gaskets will do the job?

I live in France and I'm fortunate to have E85 available at most gas stations near me for approximately -55% the cost of 93 premium gas. So it seems like a win win Should I just go full on E85 or still get a Flex-Fuel kit?

Thanks!

-L

ERIKGUNNAR

Hi Lorenzo.

I live in Sweden and I have same as you. E85 at almost all gas stations and up to 98 RON petrol. I have heads milled 0.045 and 0,040 gasket. I can run the car on 98RON with about 8 degrees lower ignition timing than E85 at WOT and up to 15 lower in some mid rpm low load knocking areas. I live in the north of Sweden so no Shell V-Power which would have been great. I guess my compression is about 13:2 and on petrol it is not really a great performer but perfectly drivable with out knock. The key to watch out for is the intake closing of your cam. That sets the dynamic compression which is really what it is about regarding if you can make it work on petrol. I had a small cam last year with early intake closing which gave very high dynamic comp. With this cam I could never ever have gone over to petrol. The engine had so much dyn compression that ignition timing was less or equal to stock C6 Z06 on E85.

So my target is best set up possible for E85 but perfectly drivable on petrol if I can not get E85 like in Norway. I think you have to make the same type of call. Do you want it running great on both petrol and E85 or more biast towards one or the other.

MTPZ06

Flex fuel kit is relatively cheap, and I like having a contingency plan already in place, in case you ever find yourself without E85.

Lorenzo Serra

Hi Erik,

Thanks for your feedback. I also have access to 98 RON which should be about the same as 93 MON right? I'd like to set my build with an edge bias for E85 as I'll be running it close to 100% of the time unless I travel out of the country to Italy or something unusual.

However; since my local rules are pretty strict, I can't really run a large cam and will likely keep my stock cam or perhaps go for a baby cam. I guess that means I'll be running a very high DC. Is 12:1 a good compromise for my build?

Thanks!

ERIKGUNNAR

Tell me more about your French strict rules and I can compare to Sweden rules which I know how to pass.

Chiselchst

Are the Flex fuel analyzers robustly accurate?
If not, is it too out of line to consider redundant meters?
I've got one E85 fueling station source close by, but only one...
(I fear the meter failing when/if I can't find E85)