Stage7

Carlos,

At 13.6:1 compression, is it even possible for him to run 93 octane with your double tune switch setup? What's the max compression for a "flex fuel" setup 93/e85 that would still make good/safe power on 93 octane?

Thanks

0Myhardtop

Mr. Punisher,

I am not sure if 60lbs injectors will be enough for your 454cid engine with high compression and E85.

If you are concern about the fueling and own a C6Z, then I believe all you have to do is swap for the 80lbs units and call it a day; based on what I’ve seen thus far, there is NO need for bigger lines, bigger rails or dual pumps. I am sporting billet fuel rails and 80# injectors and that’s it and I’m spraying a 120hp dry-shot! My IDC are in the 44% or so range N/A and 56% or so NOS. I decided to install the rails more for cosmetic purposes vs. necessity; my car makes a little over 800rwhp on the juice and it seems to be fine.

If I were you, I would mill your heads to achieve at least 13.5CR installed. Personally, I would shoot for 14.1CR and let her rip with a nice cam with valve event timing that promotes great cylinder pressure and favoring the exhaust. That thing may make between 700 and 715rwhp N/A!!!!

Hope this helps

Thanks,
Carlos

FNBADAZ06

Wonder the same thing, as I'm in AZ where 91 is the norm.
I was thinking that with a 13:1 , I might be able to run 91 with meth injection and a conservative tune until I could reach another E85 station. Going out of town with minimal E85 station support would kill the idea of driving the car further than 200-250 miles from home

0Myhardtop

Some may call me a dare devil while others may call me crazy due to the fact that I would do/try things just to scratch my itch of interest. Here is an example, this past Saturday was hot and muggy here in Dallas, and I drove my Z to make a few errands after the shop.

As I ran to the airport, I noticed that many Chicagoans were down here to see the dismantling of the Dallas Cowboys. I happened to be driving along hwy 114 towards the airport and witnessed a wave of BEARS fans from Illinois heading towards the Jonesmajal (the new Cowboys stadium) so I decided to follow the crowd…I have IL tags on my Z and many of these rowdy fools were nagging me to mesh on the loud pedal.

I was running low on E85 to begin with (less than half tank), I knew I had enough to make it back to my side of town and certainly had enough to reach the next E85 station in Irving Tx but my previous decision of following the IL crowd negated going the other direction (away from Arlington TX) to refuel with the sweet stuff. So what did I do, I went ahead and decided to add 6.1gallons of Shell 93oct, monitored my readings via my HPT [I have a laptop in the cargo net at all times] and never noticed any knock or any issues. I am not sure what the final mix was regarding octane levels but nevertheless, the car simply ran fine.

A BIG part of my tuning practice is safety! As I mentioned earlier, you do not need to throw in a ton of timing into this set up to make power. Granted, every car is different but thus far form has followed function with this MACHO high compression (12.7 or more) when dealing with timing tables. However, the very important piece is the amount of compression ratio so to suppress that, the fuel and timing tables are curved as such to prevent any mishaps if and when the need of running a 50/50 is necessary although I will not race it that way and plus I run two range cooler plugs to help as well.

You can run 93oct with 13.6CR but will have to cut timing down and add fuel. I’ve seen guys use the stock Low Octane table, and ADD two degrees here and there and run fatter fuel curves (15 to 20% more fuel) with this high compression and 93oct then switch back for racing. At the end of the day you won’t make all the power there is, but at least you can run pump gas 5 days a week and then switch tunes and add E85 for the weekend.

Hope this helps.

Thanks,
Carlos

FNBADAZ06

Man...we just don't have 93 in Az (or Cali, I think)....91 is all we get.

PUNISHR TA

700 would be sweet. 14.1 is a little scary sounding though.

I dont have a Z... yet Its a Trans Am, with an LS7 based 454 LSX.

Thanks for the info though. I was looking on your site, and couldnt find any info about this cam...

0Myhardtop

The cam I was suggesting for what I think you are doing would be custom made.

14.1 scary! Why?

Thanks,
Carlos

PUNISHR TA

Ive always associated High compression with reduced reliability

kumar75150

If you have the right octane and tune, high compression is fine. The only downside I've heard is the consistency of the E85 mix. Carlos seems confident he can work around that.

One factor you might want to consider is resale value of the car. E85 is not available everywhere or liked by everyone.

0Myhardtop

Not IF tuned and maintained correctly.

Keep an eye on knock because knock beats up your bearings, keep an eye on temps because high temp is never good, keep an eye on fuel delivery because proper fueling is essential for a long life, keep an eye on oil press and quality. Keep and eye on spark plugs, keep an eye on timing settings and keep an eye on fuel octane/quality.

If you are that concerned, then run 13.25 or 13.1 or even 12.5. With good internals and good tuning, a high compression N/A motor will last; most of the time much longer than a high boosted a FI application.

Thanks,
Carlos

PUNISHR TA

Yea, ive heard you have to test your E85 to maek sure its not a bad batch.. As far as resale... I just have a 01 Trans Am right now... So my motor is worth ~15k... while my car is worth... well less than that, so i wont be selling anytime soon.

Thanks for the help. Im not really one to get concerned... if it blows ill build it better next year. If im gonna go E85, id really like to maximize the potential... ie. compression.

How much can you mill LS7 heads, to raise compression...? Before the flow is distorted, and the mounting get too weak.. or whatever can go wrong.

PRE-Z06

Nice results as always Carlos! Used to limp my all iron 12.5:1 v8 vega around on 93+booster, when I couldn't fill up with Av gas...with today's technology it shouldn't be scary running that much compression(a lot of high end foreign automakers/bikes run that much from the factory) but for the guys with only 91 available I'd carry a bottle of some good octane booster around just as a safety precaution

0Myhardtop

I’m not sure where this entire bad E85 gas assumption is coming from??? I guess the same can be said about 93oct gas; you can sometimes fill up with bad 93oct gas from certain stations at times but I haven’t noticed this phenomenon with E85. The only thing to watch when it comes to E85 is winter blends; many stations make the switch to E70 for the cold winter months.

As far as the milling limits of the LS7 heads for high compression, who knows what it is. The most we’ve tried is 48-to-50cc or so by angle milling. First, the heads are flat milled about .10thousands then rolled/angle milled based on expected goals and cam choice. The highest CR I’ve seen is 14.1 but most fall into the 13.1 to 13.5 range.

Please keep in mind that we are achieving these CR using with GM stock LS7 gaskets and for the most parts, installation is done with the stock pushrods due to milling method. Of course, intake manifold must be notched on all four corners so it sits down on the heads and thus lining up the intake ports.

Hope this helps.

Thanks,
Carlos

0Myhardtop

Another E85 13.5 CR customer this week.

Results: 630/571...he will be posting soon. I may post for him if he can't figure out how to post pics.

Thanks,
Carlos

mustang281man

hey carlos, do you think you could explain angle milling a little more? how much do you guys usually angle mill to achieve 12-12.5:1 compression? do you guys have a price to just mill a set of heads or do you only do port/polish/mill? looks like that last z06 you did should run pretty good.

Six-Gun-Todd

Oh I wish that were the case in Michigan

Honestly....I'd love to convert to E85 but there just isn't enough supporting infrastructure here to make it viable. (I like to drive my car not track it) That and the fact the Z06 fuel system is not E85 compatible.....not the pump.....seals.....lines.....and I have no great desire to change all of those things on my 08.

Six-Gun-Todd

Angle mill - to machine the mating service in a way that tightens compression without dramatically effecting inlet port position. In some cases it also unshrouds the inlet valve for better flow numbers.

mustang281man

yea i saw that definition somewhere else, but im just trying to visualize how they mill the head compared to flat milling it.

0Myhardtop

Besides the injectors, there is NO NEED to change any other fuel componets on your Corvette to run E85. I repeat, you ONLY need to change your fuel injectors then tune of course.

Hard to find E85 stations in MI??? Many midwest states have a plethora of E85 stations amigo.

Thanks,
Carlos

0Myhardtop

We can certainly simply mill the heads and leave everything else status quo. Most guys opt for the porting and polishing of course, changing the exhaust valves and replacing all the guides.

We flat mill the heads .10 then roll the heads [angle mill] to achieve desired CR. You can achieve between 12.0 and 12.5CR through flat milling. In the case of angle milling, you are often rewarded with better flow and burn effeciency.

An effecient engine will run smoother and cooler and in many cases, make more power with less timing.

Yes, that Z runs good, really good. Today we strapped mine down just to test a few things: lower timing (17-19), fatter fuel on top (12.2)/leaner on the bottom (12.5) and switched to (TR6 vs TR7) for the winter and made: 640/578 643/579 and 638/577 on repeated runs...no engine off!!!

Hope this helps.

Thanks,
Carlos