Racing tonight at Wild Horse Pass (formally Firebird) in AZ

[A.J.]

Last night after racing I dropped my van and tow dolly off at the shop and drove my truck home because I didn't feel like swapping tires. Today I drove my van home and on the way I think to myself, "I should switch my boost down to low (15 psi) because I don't need to be on high (20 psi) on city streets." I look at my boost controller and it's already on low boost. I think I got my 13.5 last night on low boost. I don't remember switching to low boost last night or remember looking at my boost gauge at all. I was always looking at my tach so I'd know when to shift.

[tryingbe]

Nevermind that, get another set of wires made and then go for 25psi.

[turbo84voyager]

Very nice job, congrats!

[turbo84voyager]

How much difference in timing with the E85 vs 91? I would love to go that route but unfortunately it is not available around here.

[A.J.]

How much difference in timing with the E85 vs 91? I would love to go that route but unfortunately it is not available around here.

We were able to add about 20* of timing. I tested the ethanol content day off the race and it measured to be E80.

[Ondonti]

Do you have an electronic controller? I have one that decides to set itself to high boost sometimes so I always have to check.

[A.J.]

Do you have an electronic controller? I have one that decides to set itself to high boost sometimes so I always have to check.

Yes it's an electronic one. A Greddy Profec B-spec 2. I'm almost positive I didn't set it to high boost. After we got done tuning full throttle we were tuning part throttle so I had it on low and I never set it to high at the track.

[zin]

That is pretty impressive!

Did I read it right, that you added an additional 20* of timing?! And if so did you arrive there by adding until you didn't see more power?

It seems like a lot, and has me wondering if the fuel was what was holding you back, or is the E85 covering for some combustion instability?

Any way you slice it, the results are impressive!

Mike

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That is pretty impressive!

Did I read it right, that you added an additional 20* of timing?! And if so did you arrive there by adding until you didn't see more power?

It seems like a lot, and has me wondering if the fuel was what was holding you back, or is the E85 covering for some combustion instability?

Any way you slice it, the results are impressive!

Mike

[A.J.]

That is pretty impressive!

Did I read it right, that you added an additional 20* of timing?! And if so did you arrive there by adding until you didn't see more power?

It seems like a lot, and has me wondering if the fuel was what was holding you back, or is the E85 covering for some combustion instability?

Any way you slice it, the results are impressive!

Mike

We added the timing slowly and this is all street tuning so we don't know if we stopped making power. In the next week or so I want to get it to the dyno for tuning. I think Harry chose to stop where he did because he didn't want to push it and risk engine damage.

[zin]

Alrighty then. I'll be very interested in seeing if it's wanting the timing, or is simply tolerating the excess timing due to the fuel ...

Mike

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Alrighty then. I'll be very interested in seeing if it's wanting the timing, or is simply tolerating the excess timing due to the fuel ...

Mike

[turbo84voyager]

One if the ways to add timing is to keep slowly adding it until you get CEL knock (As long as you have an accurate knock sensor). Then back it off a degree or so. 20 degrees is a lot. I know the ski ramp turbo pistons like more timing but wonder how they react to the e-85 vs aftermarket dished ones. I wonder if its the fuel that is allowing this much more timing or a mix of the fuel and the turbo pistons.

[A.J.]

Alrighty then. I'll be very interested in seeing if it's wanting the timing, or is simply tolerating the excess timing due to the fuel ...

Mike

Could you explain this a little deeper? It's seems like they are one in the same to me. The factory SRT-4 tables I got from SRT forums has a lot more timing than I can use for my engine on 91 octane. When I used the factory tables my van was gutless, I couldn't drive it. The only difference is the PCM I'm using and a distributor over the coil packs. So the engine it self wants more timing but until I put in E85 I couldn't run it.

One if the ways to add timing is to keep slowly adding it until you get CEL knock (As long as you have an accurate knock sensor). Then back it off a degree or so. 20 degrees is a lot. I know the ski ramp turbo pistons like more timing but wonder how they react to the e-85 vs aftermarket dished ones. I wonder if its the fuel that is allowing this much more timing or a mix of the fuel and the turbo pistons.

That's the way we did it with 91 octane (add until we saw knock). There were a couple of occasions we saw the check engine light flash so we backed it off but I think it was only twice. It is definitely the E85 that allows me to run so much timing now. When I get some time I'll post my 91 octane tune with the E85 tune over it.

[turbo84voyager]

Could you explain this a little deeper? It's seems like they are one in the same to me. The factory SRT-4 tables I got from SRT forums has a lot more timing than I can use for my engine on 91 octane. When I used the factory tables my van was gutless, I couldn't drive it. The only difference is the PCM I'm using and a distributor over the coil packs. So the engine it self wants more timing but until I put in E85 I couldn't run it.

A.J. Can you explain this a little better? Where you getting knock using the factory SRT4 tables? I am a little confused and curious on how it was gutless with too much timing since it is usuially the other way around. I would expect bad knock before loosing that much power. Retarding the timing can help to spool the turbo.

[A.J.]

A.J. Can you explain this a little better? Where you getting knock using the factory SRT4 tables? I am a little confused and curious on how it was gutless with too much timing since it is usuially the other way around. I would expect bad knock before loosing that much power. Retarding the timing can help to spool the turbo.

I wasn't getting knock with the stock SRT-4 tables, it was just gutless. I never drove it hard enough to get it to knock. I got knock tuning on 91 octane so we'd back off the timing or add fuel. When tuning on E85, I got the check engine light to flash twice and that was the only time it ever knocked.

[zin]

Sorry I wasn't being clear... just gotta get in my head!

In one scenario the engine may not be very efficient, and therefore needs more timing to make power, such as when a big "pop up" piston is used, and creates a barrier for the flame-front to more around, taking more to time travel and thus needing more "lead".

The other is when all other things being equal, the higher quality fuel is stable enough to allow higher HP levels/cylinder pressures before detonation sets in.

Adding 20* of timing, if that's what it needed to make power makes me think the engine has a combustion issue causing it to need that extra time/lead to make power (build peak pressure at approx 15-20*ATDC), that is unless the previous tune for 91 octane required extra retard to prevent it from knocking.

Total timing required would be a clearer comparison, 91 vs E85.

I'm expecting that the E85 was more stable, and added some cooling to the combustion chamber, etc.

I'm very interested in the E85 as there is a station close to me that sells it, and while it's a crappy DD fuel, it would be nice to get what amounts to a "low grade" race fuel to have some fun with, and a turbo car seems to be made to order for it!

Mike

[tryingbe]

1 The higher autoignition temperature of Ethanol (689 degrees F, compared to gasoline's 475 degrees F) enables E85 to be more knock-resistant and handle more boost or higher compression.

Read more: http://www.importtuner.com/tech/impp...#ixzz2yLuUtoHn

[zin]

True, but it doesn't burn that much slower to want /need an extra 20* of timing, so I'm curious if the gasoline tune was that knerfed to not knock, or if there is something else going on.

Mike

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True, but it doesn't burn that much slower to want /need an extra 20* of timing, so I'm curious if the gasoline tune was that knerfed to not knock, or if there is something else going on.

Mike

[tryingbe]

SRT4 engine was never used on a SMEC car from factory, so there is no tune to start from. The tune was put together from getting idea from various calibrations (TIII cal, 8valve cal, srt4 cal, and etc.) just to get it running somewhat ok. I added timing in the 91 octane tune until the check engine light flash then I backed off. With E85, I was able to add a LOT more timing before it knocks. I have no idea what make the E85 tune so timing hungry and resistant to knock, but it works. Of course, 91 octane tune was started in summer, and E85 tune started in winter. Plus AJ been constantly upgrading his van and fixing faults, so that might have something to do with that too.

[turbo84voyager]

I really think the ski ramp pistons have something to do with it. Did you end up adding more timing than the SRT values? I am going to be running a similar setup but I am running aftermarket pistons so my timing will be quite a bit different. Did you ever try running it with 8 valve timing tables? If so how did it run? I would expect it to not have enough timing. Does A.J. have an EGT gauge? How were the temps? I found this to be a great tool when adjusting the timing when I did my 2.5 g-head cal. Not enough timing and the EGT's were through the roof. The hybrid / 2.4 with dished piston timing tables I have looked at have timing values similar to the 8 valve motors and dont have a ton of timing. This is why I think it all has to do with the pistons.

[zin]

Ok, that makes sense, sounds like it's a combination of things... not to be critical of the tune (or tuner), but given how the timing was arrived at, it is probably a bit heavy on the amount of timing, and the 91 tune was probably a bit light, the fuel being the defining factor.

My crystal ball says the E85 tune will probably want less, but its qualities allowed more than optimum timing (at this boost level), if so what you've established is that there is much more"room to maneuver" with E85 without going "terminal" as would be the case with 91octane.

That's my theory, and I'm sticking to it! (At least until it's proven wrong, lol).

Nice job with this tune BTW, results speak loudest of all!

Mike

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Ok, that makes sense, sounds like it's a combination of things... not to be critical of the tune (or tuner), but given how the timing was arrived at, it is probably a bit heavy on the amount of timing, and the 91 tune was probably a bit light, the fuel being the defining factor.

My crystal ball says the E85 tune will probably want less, but its qualities allowed more than optimum timing (at this boost level), if so what you've established is that there is much more"room to maneuver" with E85 without going "terminal" as would be the case with 91octane.

That's my theory, and I'm sticking to it! (At least until it's proven wrong, lol).

Nice job with this tune BTW, results speak loudest of all!

Mike