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Turbo98
Joined: 03 May 2007
Posts: 100
Location: Misouri
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 Posted: Thu May 17, 2007 7:51 pm Post subject: |
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I thought MBT means "Maximum Brake Torque" timing. I doubt most people with high performance engines running on the street (or anybody for that matter) knows what the MBT is for their engine. I don't. Especially if there are any modifications to the engine. What I seem to have noticed when doing some research is that most high performance engines aren't running MBT timing with 93 pump gas. So it seems there is some pretty good power to be added by using E85 and bumping the timing until it doesn't help anymore. Then I assume you've reached MBT. In the case of an E85 turbo Mustang, this guy ran up the timing until it didn't gain any more power and the results were:
6 lbs boost, 35 degrees timing, 575rwhp
13 lbs boost, 29 degrees timing, 872rwhp
20 lbs boost, 24 degrees timing, 989rwhp.
I know the power numbers are probably irrelevant but it is just an example of some serious power on E85. There is no way he could have run the timing nearly that high on 93 octane. Maybe 16 degrees or so only on 6 lbs.
So, I think being able to advance the timing is one of the power advantages of this fuel-especially on any forced induction application. Really, the only way is to run it up until it doesn't make any more power and I'm sure the total timing may surprise you. This guy ended up running 30 lbs of boost and saw no detonation!I will find out soon.
Anyway, I'm not an expert but that's what I've ovserved. |
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BlownEthanol
Joined: 08 May 2007
Posts: 43
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| Posted: Fri May 18, 2007 8:12 am Post subject: |
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| Turbo98 wrote: | I thought MBT means "Maximum Brake Torque" timing. I doubt most people with high performance engines running on the street (or anybody for that matter) knows what the MBT is for their engine. I don't. Especially if there are any modifications to the engine. What I seem to have noticed when doing some research is that most high performance engines aren't running MBT timing with 93 pump gas. So it seems there is some pretty good power to be added by using E85 and bumping the timing until it doesn't help anymore. Then I assume you've reached MBT. In the case of an E85 turbo Mustang, this guy ran up the timing until it didn't gain any more power and the results were:
6 lbs boost, 35 degrees timing, 575rwhp
13 lbs boost, 29 degrees timing, 872rwhp
20 lbs boost, 24 degrees timing, 989rwhp.
I know the power numbers are probably irrelevant but it is just an example of some serious power on E85. There is no way he could have run the timing nearly that high on 93 octane. Maybe 16 degrees or so only on 6 lbs.
So, I think being able to advance the timing is one of the power advantages of this fuel-especially on any forced induction application. Really, the only way is to run it up until it doesn't make any more power and I'm sure the total timing may surprise you. This guy ended up running 30 lbs of boost and saw no detonation!I will find out soon.
Anyway, I'm not an expert but that's what I've ovserved. |
Well heres what I am hearing (or think I am) but I could be wrong: People always say more timing is better, wow he can run 24 degrees of timing with 20 pounds of boost thats amazing right? Well its not how much timing you can run but if you have your timing where it needs to be. THe only way to know for sure is to dyno the car, but maybe E85 has such great cooling properties that it allows you to go well past the optimum amount of timing. Don't you always want to time the flame front jsut right so that it hits the piston at around 10-12 degrees after top dead center? Anything before this is going to cause a drop off in power and risk detonation, anything after this is going to cause a drop off in power right?
I am under the impression that timing is a mark that you hit and not how far you can go. If you are shooting a free throw in basketball you aim for the hoop, not throw the ball as far as you can right?
This would mean that if you take an engine and you know that 24* of timing at 7 psi of boost is exactly mbt, then as you add boost you will have to lower timing to hit mbt. People usually just talk about how much timing they can run: "Wow I can run 25 pounds of boost and still up to 24* of timing before it pings!"
In the example of that Mustang, you can see that he lowered timing as he raised boost, this seems to back up what I am saying. |
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Turbo98
Joined: 03 May 2007
Posts: 100
Location: Misouri
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| Posted: Fri May 18, 2007 8:20 am Post subject: |
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I would have to say that you are correct about the anti-detonation properties of Ethanol. Between the higher octane and cooling properties, it is apparent that you can advance the timing past MBT without detonation. This means to me that you can basically advance the timing until it makes no more power. then you've reached your best timing. Detonation doesn't seem to be an issue but I'm sure you can get it to detonate with huge boost, high compression, etc. But from what I've seen, in most cases, it is hard to do.
| BlownEthanol wrote: | | Turbo98 wrote: | I thought MBT means "Maximum Brake Torque" timing. I doubt most people with high performance engines running on the street (or anybody for that matter) knows what the MBT is for their engine. I don't. Especially if there are any modifications to the engine. What I seem to have noticed when doing some research is that most high performance engines aren't running MBT timing with 93 pump gas. So it seems there is some pretty good power to be added by using E85 and bumping the timing until it doesn't help anymore. Then I assume you've reached MBT. In the case of an E85 turbo Mustang, this guy ran up the timing until it didn't gain any more power and the results were:
6 lbs boost, 35 degrees timing, 575rwhp
13 lbs boost, 29 degrees timing, 872rwhp
20 lbs boost, 24 degrees timing, 989rwhp.
I know the power numbers are probably irrelevant but it is just an example of some serious power on E85. There is no way he could have run the timing nearly that high on 93 octane. Maybe 16 degrees or so only on 6 lbs.
So, I think being able to advance the timing is one of the power advantages of this fuel-especially on any forced induction application. Really, the only way is to run it up until it doesn't make any more power and I'm sure the total timing may surprise you. This guy ended up running 30 lbs of boost and saw no detonation!I will find out soon.
Anyway, I'm not an expert but that's what I've ovserved. |
Well heres what I am hearing (or think I am) but I could be wrong: People always say more timing is better, wow he can run 24 degrees of timing with 20 pounds of boost thats amazing right? Well its not how much timing you can run but if you have your timing where it needs to be. THe only way to know for sure is to dyno the car, but maybe E85 has such great cooling properties that it allows you to go well past the optimum amount of timing. Don't you always want to time the flame front jsut right so that it hits the piston at around 10-12 degrees after top dead center? Anything before this is going to cause a drop off in power and risk detonation, anything after this is going to cause a drop off in power right? |
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