[Texas_Ace]

I have a switch at the steering wheel that I can change to high boost at a press of a button. It's my ghetto version of boost by gear. I run low boost setting in 1st and 2nd for better traction and high setting for higher gears. As long as E85 keeps knock under control, the engine should last for a while. I don't know about this C series tranny though.

You should have no issues with knock on E85 and a good tune. Stuff is darn hard to make knock even at power levels 2x and even 3x yours.

 

[Hardrvin]

You should have no issues with knock on E85 and a good tune. Stuff is darn hard to make knock even at power levels 2x and even 3x yours.

Depending on a lot of factors. I can run a 502 and make those power levels on 87 octane.

Agreed that E85 is wonderful stuff, but that's a bit broad as a generalization.

I would agree that he'd probably tweak a rod due to torque prior to hitting the knock threshold with E85 on his motor.

 

[Texas_Ace]

Depending on a lot of factors. I can run a 502 and make those power levels on 87 octane.

Agreed that E85 is wonderful stuff, but that's a bit broad as a generalization.

I would agree that he'd probably tweak a rod due to torque prior to hitting the knock threshold with E85 on his motor.

I was talking about his motor and other motors like it. There is an 800whp 2zz on E85 that had no issues with knock for example.

Naturally if you add more cylinders you lower the cylinder pressure per-cylinder and thus can make more power on lower octane fuel.

 

[thangcu35]

lol that 800whp 2zz is fully built with 9:1 CR. I'm running the stock 11.5:1, if anything it's my ring land that will go. 2zz rods are not known for failure

 

[Texas_Ace]

lol that 800whp 2zz is fully built with 9:1 CR. I'm running the stock 11.5:1, if anything it's my ring land that will go. 2zz rods are not known for failure

I know of cars running 13:1+ compression, no intercooler and 40psi+ of boost on E85 without knock. You will be just fine as long as the tune is on par.

Heck EVO's will run ~30psi of boost with ~11:1 compression ratio on PUMP gas.

My next build will be high compression as well, just not sure how high yet. Really depends on how high I can get it without valve interference issues and/or disrupting the airflow too much.

 

[thangcu35]

Spent a month building a new engine. Sleeved forged 9.5:1. Just need to break in and hit the dyno.

 

[Texas_Ace]

What happened to the old motor? Is the new motor lower compression then the old one? Why the switch?

 

[thangcu35]

I was changing valve stem seals in the old one and dropped a valve in the cylinder. I needed to pull the engine so I decided to build it while it was out. This new engine has 9.5:1 wiseco vs stock 11.5:1.

 

[Texas_Ace]

Why drop the compression so much? With E85 it should be no problem and it appeared to love the high compression as it sat?

 

[thangcu35]

It was fine for the boost level (12-13psi) but as I increase turbo pressure, I have to keep dropping timing even more (to the point where I know it's approaching the point of no return). If I keep push the turbo to it's outer islands of efficiency, even E85 can't save the engine. I had the choice of making more power with either stronger compression, or simply force more air in with less compression. I simply chose the latter because it gives me a safer margin in the tune and I have more room for more power in the future. I've seen documentations from the Subie guys that they lost power after going to higher compression, and they couldn't notice any improvement in low to mid range.

 

[Texas_Ace]

Why did you have to drop timing? Were you actually getting knock or just doing it out of normal tuning practice?

I know of plenty of cars running E85 that run timing that would otherwise be considered stupid high.

For example Aarons 830whp was done on E85 with timing values that are normally used on pump gas at a mere ~17psi IIRC. He on the other hand was running 41psi+.

Lots of other examples like this as well on other cars so not sure why you had to reduce timing so much. Even know of cars running 13.5:1+ compression, non intercooled and boosted making 1500whp+ on E85 without an issue.

Not dissing the choice, it will work just fine, just curious for the reason behind it. I am actually gonna try to get my compression up as high as possible without doming the pistons more then I want.

 

[thangcu35]

If you tune E85 by knock count alone, that is a recipe for blown engine. My method is MBT and I do it on pump gas also. E85 can mask knocking to the point that you can go past MBT without knowing. I can add in 5 more timing to my current table and my knock count won't change, but my power would either stay the same or go down, meaning cylinder pressure is starting to rise exponentially. This is where ring lands will crack even without high knock count.

 

[Texas_Ace]

If you tune E85 by knock count alone, that is a recipe for blown engine. My method is MBT and I do it on pump gas also. E85 can mask knocking to the point that you can go past MBT without knowing. I can add in 5 more timing to my current table and my knock count won't change, but my power would either stay the same or go down, meaning cylinder pressure is starting to rise exponentially. This is where ring lands will crack even without signs of detonation.

That is the correct way of finding the max power, just surprised that you have to remove that much timing with E85. Although running less timing if still producing the power it should is actually a good thing, less negative work and a more efficient engine.

In a perfect world timing would be at 0 degrees.

 

[RickyB]

If you tune E85 by knock count alone, that is a recipe for blown engine. My method is MBT and I do it on pump gas also. E85 can mask knocking to the point that you can go past MBT without knowing. I can add in 5 more timing to my current table and my knock count won't change, but my power would either stay the same or go down, meaning cylinder pressure is starting to rise exponentially. This is where ring lands will crack even without high knock count.

That's why you use a dyno to determine MTBT rather than pulling it out of your hat.

If you reach maximum torque and you are not knock limited, you can increase boost or CR to make more power. You will have to reduce timing once you do either of these because flame front propagation increases as peak cylinder pressure rises, so you will need less timing to make peak torque.

 

[Texas_Ace]

That's why you use a dyno to determine MTBT rather than pulling it out of your hat.

If you reach maximum torque and you are not knock limited, you can increase boost or CR to make more power. You will have to reduce timing once you do either of these because flame front propagation increases as peak cylinder pressure rises, so you will need less timing to make peak torque.

What he said^ more technical way of putting it. :thumbup

 

[dvom]

Pretty sure the 2zz is the only yota engine with lift.

The '14 corolla has available variable lift for the intake cam, they call it valvematic. I think toyota may include it in more engines soon.

 

[Hardrvin]

Ignoring efficiency, you're capable of making more power with lower CR by increasing the boost.

And I'm not trying to start a long winded argument, but 13:1 and 40psi from a properly sized turbo to engine size isn't happening unless you're burning alcohol, not E85.

 

[Texas_Ace]

Ignoring efficiency, you're capable of making more power with lower CR by increasing the boost.

And I'm not trying to start a long winded argument, but 13:1 and 40psi from a properly sized turbo to engine size isn't happening unless you're burning alcohol, not E85.

True that overall max power will be had with lower compression but at the price of off-boost performance and worse drivability.

Also go tell the guys over at yellowbullet they can't run 13:1 with 40psi+ of boost and 1500whp+ who are doing just that.

In the classes they run they get weight advantages for doing this, hence why they do it.

It can very much be done. Ethanol is actually harder to light then Methanol and as such it is argued that it has a higher octane rating. Some even argue that more power can be made on ethanol although not sure I buy that.

 

[MiSterMRTwoo]

If you tune E85 by knock count alone, that is a recipe for blown engine. My method is MBT and I do it on pump gas also. E85 can mask knocking to the point that you can go past MBT without knowing. I can add in 5 more timing to my current table and my knock count won't change, but my power would either stay the same or go down, meaning cylinder pressure is starting to rise exponentially. This is where ring lands will crack even without high knock count.

Im a little new to this whole tuning thing, what is mbt and mtbt?

 

[Texas_Ace]

Im a little new to this whole tuning thing, what is mbt and mtbt?

Max Break Torque.

Basically you advance timing until power stops going up or you get knock. Whichever comes first.