guys .. i am curious. i know that static compression is different than dynamic compression, and each setup .. depending on displacement, dynamic compression, and cams will vary to what the minimum fuel octane requirement is needed. if hypothetically, i have a setup .. lets say a 2.0L B-series .. 13.0:1 compression .. some pretty big cams, and im tuned on pump gas. if this tune already reached its max timing that it likes, and is still not at the knock threshold, does that mean that by switching to say a race gas or E85, i will probably see minimum gains, if any? i ask this because i recently went from 93oct to E85 on a the setup mentioned above, and saw a gain of 2whp.(i actually think the 2whp came from a 30min cool down lol) timing stayed the same in both maps .. (29degrees) .. obviously fuel had to be changed drastically. if thats the case, on my particular setup, wouldnt it be wise to just leave it at pump gas??

 

That's your problem the timing stayed the same. Higher octane and i believe lead as well resists knock better allowing for more timing advance and more peak cyl pressure/tq. You should be able to run at least a few more degrees advance going from say a 93 pump to a leaded race fuel over 100 octane

 

^ yea thats what im trying to say. i was at 29deg. timing with pump gas. i switched over to E85 and the timing at 32deg., and it acutally lost power. It didnt regain the original power until i slowly dropped the timing back down to 29deg... which leads me to believe i was already at "max timing" with the pump gas. Which leads me to my original question, if the setup... even one that might not "suppose" to perform well on pump gas, reaches the max timing needed, will switching to E85 or a race fuel gain anything at all?

 

Im assuming the afr was tuned correctly? Lambda stays the same but since the stoich ratio is different between gas and e85, it makes the appropriate afr numbers be different.

 

yes the fuel was tuned. it wanted roughly 41% more fuel. obviously we tried different settings, and it seem to want to be on the richer side. first thing that cross my mind after the tune was done, was that maybe the dynamic compression for this specific setup didnt need the extra octane. of course the static compression is 13.0:1 so u figured that pump gas is not ideal, but maybe with the camshafts, CNC head, etc played a role.

 

Did you try less than 29 degrees of timing to see if it liked that?

 

yea we tried a range of 27.5-32deg. 29 was the sweet spot... (also for pump gas)

 

Where are you reaching MBT at? Going to E85 or something like FTW will probably see gains. A buddy of mine actually was reaching around the same as you on racegas, and he ended up going to FTW and gainned another 10whp across the board after a few more degrees were added. MOST of the time, anything in the area of 24-30 on a NA b series seems to be the normal for pump gas.

 

Track tuning will really show some difference in what the motor may like, i've experince this a few times and found track tuning and actual dyno tuning might vary up and around 2-4 degrees depending on mph.

 

from my experience, there are a lof of tuners who do not mess with ignition tuning on a typical honda dyno session. So it makes sense that you only made 2whp gain going from pump gas to e85.

However, if your compression is not very high, even with ignition tuning, it is possible not to make a lot more power with e85 depending on the engine.

A friend of mine emailed me a tuning map that a known racer/tuner did on his car and I looked at it and asked the tuner.. "hey man, why didn't you touch ignition?"

His answer was "it was just a normal tune man, we don't have all day" lol

So when you are changing fuel, you have to invest the time or money to scratch off the last tune and go at it again.

When testing cams back to back, or fuel or any parts really that seems to be a big problem with honda tuners. They always seem to be in a hurry to tune fuel and get you out the door with some nice STD or uncorrected numbers.

As power goes up, it becomes more important to have a professional tuner work on the car. At the same time, these guys also want $1000 per session and they want the car all day and they do not want you to be around probably so I understand that as well. I would never let any tuner have my engine or car without me present but if that is your day job tuning car for a living, like Jeff Evans for an example, I understand that you cannot possible every day be in the mood to explain what you are doing with each persons car while they are asking the same questions again and again.

The rule of thumb with ignition is to increase it on the dyno and once you stop making more power, pull back a few degrees and leave it there.

What I find interesting on some of hondata base maps is to look at how Doug and Derek from Hondata have tuned ignition on their base maps.

With all motor you are mostly going to be ok playing with different kind of fuels and E85 but with turbo you have to watch out because no matter how good of a tuner you are, a boosted engine can blow from unstable e85 mix. It happens all the time and people go back to Q16 and don't tell anyone about it.

 

I have seen the same results going over to E85 from pump fuel,until we stated playing around with injectors,injection timing and fuel pressure then we where able to increase to the timing numbers we wanted to see for our engines.

 

DDTECH - im not too sure, ill ask the tuner. i believe it was around 7500rpm.

Nikos- yea it sad that alot of tuner rushes a tune, but i guess it makes sense since alot of guys arent willing to pay up. but in our session, we did play with timing as stated above. which is why i agree with what you said about the compression not being high enough. again, this what im asking about in the first place.. if your compression is not high enough, and u achieve max timing with pump gas, going to a higher octane will not yield much.

Uncle Dave- i can try playing with the fuel pressure. but how do u play with the injectors and injectors timing? is there an option for that in the hondata s300?

 

In fuel compensations in S300 you have injector phase that is what they call it.
What injectors and fuel system setup are you using?

 

thanks Uncle Dave. im using the Injector dynamics 1000cc , Aeromotive fuel pressure regulator set at 55psi, and a Walbro 255 fuel pump.

 

You could probably up the pressure, and get a better atomization a bit..

I think you should try a E85 blend and just see, wont hurt anything.. if i had to guess you should be able to make a bit more, i wouldn't expect 20whp, i'd see 8-15 fesable though.

 

Uncle Dave is 100% correct. this is also called DEAD TIME.

injector dead time values come with your aftermarket injectors

if you don't have the values, follow this guide from haltech

http://files.haltech.com/downloads/p...nced_fuel.html

good luck, let us know if by adjusting your dead times you picked up the power.

here's a similar thread to see where in hondata s300

https://honda-tech.com/forums/engine-management-tuning-124/setting-up-injector-dead-times-s300-2947586/

 

Nikos DEAD TIMES are the voltage offset for the injectors this will also change with fuel pressure,I was talking injector timing as to when it fires the injectors.

 

DDTECH - at this point, I'm only interested in pump E85. I have it about 15min away, but I'm starting to think about switching back to pump gas for less oil contamination and gas mpg. without any gains with pump e85, I doubt a race e85 blend will do gains that will justify the price. I made this thread to confirm if this is true... that a setup that doesn't need anymore than pump gas... will only benefit slightly from Race fuels. I will however test and play around it some more before giving up.

Nikos - yea I already adjusted the dead time according to the specs from Injector Dynamics.

Uncle Dave - any advice on what to try first?