fid

iTrader: (18)

Maybe that is what I should have said the first time and saved the confusion and carpel tunnel .

l2r99gst

iTrader: (2)

But this doesn't make sense to me. If you can reach MBT on your tunes on pump gas, then you're never going to be on the ragged edge. If you have reached MBT on every single car you have tuned on pump gas, then they are either NA cars or running very low boost.

Almost everyone I know has the exact opposite experience as you. I'm not calling you a liar by any means...just trying to understand. An octane limited fuel, like pump gas, usually means that you can't reach MBT because of knock. That's why we run higher octane fuels...so that we can reach MBT and maximum torque at the same boost levels.

fid

iTrader: (18)

No, I understand. I am not trying to say every engine has a single MBT number and then that is it. I am trying to say there is a MBT for a engine that is knock limited and there is a MBT number for that same engine when it is not knock limited. In respect when running 93 octane and a race fuel. For example:

-2.9l VW VR6 (just because that is what I tuned alot of ). 93 octane it reached a max torque at 22 degrees and started to barely rise/fall off with every degree raised. But with every degree raised it still gained hp but started to knock. It would be safe to say that the MBT is in the area of 22 degrees.

-Same motor on C16 made peak torque 30 degrees and same senario torque started to level/falloff with every degree of advance but hp still increased but the motor doesn't knock.

Now I think in the 2nd example the motor on race gas the MBT of the motor would be in the area 30 degrees of advance.

Two different MBT's because one example was knock limited and the other was not.

I will ask a question to you. How would you tune a motor with no knock device, on pump gas and no prior knowledge of what timing the motor operates on and know when you have reached MBT? What I have experienced is to follow the torque line (as referenced by Binary) and watch for very low increase, leveling and/or drop off in peak torque. MOST motors will have a MBT that is closely proceeded by knock when the motor is knock limited, not horsepower but torque. I hope that helps even a smidge to what I am trying to explain.

crcain

Both the examples above are N/A application?

Every EFI University person I speak to is stuck with same notion you are asserting. And they have the same difficulty acknowledging the simple notion that, on a high boost engine, low octane fuel, knock will happen BEFORE torque falls off.

crcain

And I had mentioned the road tuning aspect, because, there are amazing tuners out there that do impeccable tunes on the road. How do they do this without a dyno giving them a torque/tractive effort reading? It's because they tune the car to a safe margin of knock.

fid

iTrader: (18)

No, F/I applications.

Those same people will also say, like I did, that that is not always the case. What you are insinuating is that the people that have blazed the way in EFI, also creating some of the most complex and sophisticated stand alones on the planet are wrong and you know better? They know because they are the some of the most experienced tuners on this planet. Believe what you want and most likely what you are told and I will leave it at that.



And I am sure they have tuned evo's many times over which makes the job ALOT easier when doing a road tune. How are they tuning your car on the road to a margin of safety? Either with a knock device or the prior knowledge of the map they are using being a safe starting point that is how. If they are doing it by ear please let me know because I have a solar powered flashlight I would like to sell you. And what does a safe margin of knock mean and how do they come up with what is a safe margin of knock? A device to do this or do they wait to hear the marbles in a tin can sound and pull a degree and say its fine? Seriously, I am interested to know.

Mellon Racing

iTrader: (38)

with pump gas on an evo I've always run into knock first

with race gas at the track I've seen mph fall off after adding too much timing...pull the timing back and the traps go back up.

fid

iTrader: (18)

If the Ecu pulls timing when it sees knock how do you know you were going to make a broader torque band then the previous pull?

This is getting way off topic from the original post and question. My apologies to the OP and sorry for kicking the beehive so to say .

Mellon Racing

iTrader: (38)

is there a typo in your question? that doesn't make sense to me

fid

iTrader: (18)

Let me try it this way:

-You are tuning a basic bolt on evo with no boost changes throughout the pulls.

-You make 4 consecutive pulls increasing timing and the last pull the car starts to knock.

-From pull 1 to pull 2 you increase 15ft.lbs. of torque

-From pull 2 to pull 3 you increased 7ft.lbs of torque

-On pull 4 you only saw 2 ft.lbs. increase in torque and not as strong of a curve and with knock now.

It would be safe to say that on the last pull you are right at or past MBT for pump gas.

So my new, hopefully unconfusing question to you is when you add timing to your engine all the way up to the point of knock what kind of torque increases do you normally see up to that point and more importantly what does the torque curve look like for you? Because if the torque curve is falling off heavily all the way up to the point where you say you see knock first then it might not be that you are not seeing MBT because of being knock limited but because you might be missing it? And please don't take this as me being a jerk or a smarta@# because I am truly not trying to be .

Whoop_ass

iTrader: (7)

Well I think you can add timing to a point where the car will make no more power.

no this limit well be reached pretty early on pump gas but on VP import you can go mad and you wont get KNOCK!
it a law of diminishing returns.

If you started out with very low timing you will gane maybe 40-50hp just by going up a 2-3 deg.
but there comes a point where I reckon if you keep adding timing and you have the fuel to prevent DET (VP Import) you will not gain much 2-3 deg on the limit.

I have looked at a couple of posts and most of the guys with the stocker run like upto 14-17 deg at redline. now the stocker tapers like a **** and you can add more timing.
Big turbos can maintain good boost at redline, does this mean we should be more conservative on the timing on the top end scale of the RPM's

crcain

I don't understand how what you said relates to the point we are discussing. The question at hand is what occurs first, knock, or torque falling off, on a pump gas evo.

Why are you suggesting I would tune a car without a proper way to monitor an engine? I happen to use some homeade det cans.. half of which can be seen here:

http://www.clubctrl.com/headphones.jpg

But again, the subject is not how to listen for det.

sprx19

iTrader: (5)

You've either read too many books or have old ideas that need updating. With your philosophy nearly all cars would run the same timing map regardless of fuel.

In regards to your post above, maybe the engine was not making progressely(?) less torque at ANY point in the powerband before it knocked, rather it reached the limit of the fuel while the torque was climbing fast. To make this more clear, think 87 octane vs 110 octane.

You dig yourself into a deeper hole the more you post on this subject.

Mellon Racing

iTrader: (38)

in the scenario you've described the gains are big with each degree of timing added until you encounter knock...if you were to add race gas to quell the knock you would be able to add more timing and pick up more power.

Like I said before when you're on pump gas you will run into knock before you go too far with timing.

example, my car back when it was ~500awhp on 93 octane just before getting significant knock. I put in c16, dialed the AFR back to where it was on pump and left the boost the same. I was able to add 5* of timing before I saw knock again and the power increased with each degree until I reached 565awhp.

Whoop_ass

iTrader: (7)

I agree with you there Mellon.

What sort of timing do you run on the 9's you have tuned with big turbo's.
Ia m just trying to see what is sort of the limit.

I understand allot of things factor due to mods.
but lets assume your mods on an EVO9, what would you call safe timing to make power on 93.