The E85 Mystery

synolimit

I said over there I'd run e85 only as needed. Only at the track. Not sure if you saw that or not.

It's not cheaper. Saving a few cents per gallon doesn't make up the 30% faster burn rate. It's no where near cheaper!!

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13 370z-

Jordo!

Octane, tuning, and other in-cylinder transient factors aside, unless we're talking same set-up, same (type of) dyno, etc, I would take that claim with a pinch of salt.

Even if it can be achieved and verified, how long is the motor holding together as torque levels climb past mechanical tolerances? You can crack a ringland if combustion pressures get high enough, even without evidence of autoignition/knock events.

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TopgunZ

Ill admit that the more power your making, in every revolution, the motor weakens. Rods, pistons, rings, everything.

However, you can make that power with less chance of it letting go due to predet. Also you can stretch out the lifetime of that motor if you are running less boost by using more timing, which is safer to do with E.

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Jordo!

If quenching hotspots are the only issue, then, yes, that follows.

Also, if E85 has a lower stoichiometric ratio than regular petrol I believe that translates into more potential energy (i.e., combustion pressure) to get out of it, so that could be contributing too.

I have no idea what the actual mechanical tolerances are on a stock VQ37HR longblock, tho...

Are there any confirmed breaks from overpower as opposed to detonation?

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Nixlimited

Ethanol has significantly less potential energy than gasoline. That's why it takes significantly more of it (think huge injectors) to make lots of power. But it's excellent for knock resistance.

Per Wiki: Gasoline has 114K BTU/gal to Ethanol's 76K/gal.

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Jordo!

I think the key value here is latent heat of vaporization vs. amount of fuel needed to achieve peak torque, which is a factor related to stoichiometry -- check out p. 117 on down at this link.

http://martysgarage.info/manuals/bell2ttuning.pdf

It's from A.G. Bell's book on fueling 2-stroke engines, but he has the exact same formulas/rationale in his 4-stroke supercharged tuning book.

Anyway, in theory, less efficient, but more energy ultimately produced as a consequence.

Now, if E85 ends up breaking about even, then it's just less efficient, but has a higher auto ignition threshold and higher octane, in which case never mind my other point

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djtodd

Not that I know of. I'm sure mine will go eventually. I flog the hell out of it at the track pretty regularly. And that's 600+ whp on stock internals. But of course that's one of the main reasons I went with e85.

I'm just treating it as an experiment at the point. How long can I beat on it at these power levels at the track before it fails? We'll see!

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NOBLE|370Z

Some great discussion taking place here.

It would be nice if VQ owners knew whether our cars are power limited at 550WHP due to engine internal strength or if it's based solely on detonation. This is important to distinguish because guys with stock motors and FI should know what the limiting factor really is.

If a tuner could get 700WHP out of my stock engin, regardless of fuel, would I really feel comfortable keeping it there (even if there are no signs if detonation)? Definitely not lol

I'm getting my car tuned in a couple weeks and I want to be prepared so I think I'll play it safe. I'll have two maps. 1 for 91 and another for 94 octane. Regardless of the amount of power he can get with the 94 I will make sure to use a boost setting that maintains no more power than 550WHP. When someone can produce information indicating it's 600WHP then I'll change it at that point. For the long haul I think that's the best approach - IMO


NOBLE

Seb@SZ

One BIG issue that doesn't come up is the fuel pressure drop associated with a stock fuel pump assembly AND keeping it returnless. Over time the drop can get worse leaning out the AFRs. I HIGHLY, and I stress HIGHLY, recommend forced inducted 370Zs run a return style fuel system. From what we've gathered, fuel pressure drops become apparent near and around 450 whp.

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Jordo!

Can't you just upgrade to a higher output pump?

Between that and bigger injectors I'm surprised there would be much drop off unless we're talking a lot of boost pressure.

What lph and injectors are the high horsepower Z's running vs. OEM specs?

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synolimit

So stock pump, stock setup with bigger injectors and e85 on a NA is ok or no?

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djtodd

There are quite a few of us running 600+ for some time now. But admittedly no one with 20k miles or so. Just give it time

I'm convinced 600 with proper fuel, cooling, and tune is well within limits. Proof is in the pudding

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phunk

My car runs more boost on the street than it does on the dyno... tuned at 9 psi. but more often than not, on the street, my boost is 10-10.5, sometimes even hits 11. once i hit 13! lol. Its funny how the boost sounds so low if you talk to guys with 4 cylinders running around with 30-40 psi to make our power!

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TopgunZ

So Im guessing you could get past 600whp running pump gas on this stock fuel system if were seeing it getting close on a fuel requiring 25% more flow.

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djtodd

Doesn't matter how big of a pump you put in the oem return less setup. You'll never avoid that pressure drop at the big end. Everyone will see it if they measure fuel pressure at the rail.

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