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Discussion Starter #1
What are you guys running ball park timing say 20lbs boost?
i know all engines vary,just trying to get a rough baseline trying to learn
tuning efi deal new to it.is there any type table or scale to ballpark this on?
sbf 363,afr heads,10.1 compression,160 lbs injectors,bw s491/96,
thanks for any advise or help.
 

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Start around 18 and less at and below peak torque. Keep an eye on ethanol content. a2a, a2w, or none?
I would have asked th same question, and given the same response. I run 20* up 15psi and pull from there. E85 no intercooler.
 

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If you have some knowledge about what the heads, CR and fuel type would run for timing N/A there is a better way than big chunky adjustments that generally don't drive as good or perform as well at the track. Generally speaking a stock valve angle SBF with decent compression and good fuel like E85 that is ~105 octane 30* is a reasonable place to start. My race formula works the same way but is more aggressive and only pulls 0.5*/LB of boost after 10psi and up. RPM is your friend, don't lug the engine and definitely don't run a lot of boost around peak torque. Peak torque always happens at the highest cylinder pressure which is also where it's most likely to detonate. This method allows you to build a safe, consistent timing table that you can still tweak once it's working good and you can read the plugs etc.
That being said let's say 30* is our base timing so it's not a turd down low or hard to get up on the converter. We don't pull any timing until 5psi(super safe) then pull 1* for every 1# of boost. So at 10psi - 5== 5psi net boost.
5×1==5* timing to pull
30 - 5 == 25* @ 10psi

15psi - 5 == 10psi net boost.
10psi × 1 == 10* to pull
30* - 10* == 20* @ 15psi

20psi - 5 == 15psi net boost.
15 × 1psi/lb == 15* to pull
30* - 15* == 15* @ 20psi

25psi - 5 == 20psi net boost.
20 × 1psi/lb == 20* to pull
30* - 20* == 10* @ 25psi

You can do this in 1lb, 2lb, 5lb etc increments for whatever resolution you have in the timing table. You can also spot check your cells to make sure there following the curve and you don't have highs or lows that can effect performance or hurt parts. On race fuel I'm not afraid to run timing even higher than base if it needs it to spool or get up on the converter and still not pull any until 10psi. I generally only pull 0.5* per/lb of net boost. If you start off with a valid max timing value I have never seen it ever hurt parts. If I have info from where someone used a shitty map that hurt the engine and run the numbers my map would have never hurt the engine. This takes a little base knowledge but it really does work well and allows you to build a safe base map to start testing and tweak it in from there. Hope this helps.
 

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The above post is absolutely the best advice regarding timing that I've ever seen.
My timing map was initially very conservative, and pulled too much timing WAY too soon, and the car wouldn't fall out a damn tree below 15psi.
I rebuilt my map based on Brian's formula and the car really came alive and builds boost so much faster.
Mine is just a DIY street-ish 79 Camaro with a forged 6.0ls, twin s366 Borgs.
8.69 @ 160 so far, with room to go.
Like the old saying goes.....
"If your're going to do something stupid....do it carefully!
Learn to read plugs, make one change at a time, and take careful notes on what your're doing and you are unlikely to hurt anything.
Be safe!
 

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Turbo 2 is really sharing some great info right there.
I can see why folks get uber conservative with timing. But think of it this way. If you built an NA motor with moderate compression, would you run around with 20 degrees timing on e85? Of course not! It would be a turd! But your turbo engine is going to live in low or no boost for a majority of the time. When it isn't in boost, it's really just an NA motor. Treat it that way!
I am at 12.5:1 compression, and run more aggressive timing that Turbo 2 suggested....but...I am on methanol and have a loose converter that never loads the motor at or below peak torque. This gives some safety. Peak torque is where things get sketchy first.
 

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Discussion Starter #8
Thanks guys for info!
what kinda power should (ballpark) should this thing make per pound of boost?
trying to get a ball park where I will be say 10/15/20lbs
thanks again for info
 

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Thanks for the compliments guys, I try my best to help everyone. To be very simply put take your NA hp, be it dyno sheets or best guess and basically every 15psi for easy math (1bar, 1 atmosphere, 14.7psi at sea level) will be a multiple of the base hp. This is not the gospel and there are plenty of potential problems that can effect these values but with everything in the ballpark it should be close to the following. So 500hp engine is:
1000hp @ 15psi
1500hp @ 30psi
2000hp @ 45psi
**Using the same simplified math it equals about 33hp/psi
 

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That being said let's say 30* is our base timing so it's not a turd down low or hard to get up on the converter. We don't pull any timing until 5psi(super safe) then pull 1* for every 1# of boost
Coming from a guy like me that runs only VP C16.. And doesn't know a thing about E85.. That's seem to be "SUPER DUPER" safe..

How are guys making so much power on E85 ??
 

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My personal experience here. My 388 SBC on E85 27 psi no intercooler ran [email protected] at 3800lbs. Was actually soft on the beginning of the run. Engine likes 35degrees NA but I run it at 39 as it comes up on the converter quicker and I pull no timing until 10psi. After that I pull it down to 25* by 27 psi. I’m good to there for sure. I turned it up to 28psi and pulled it back another degree to 24* to be safe and it picked up 2mph and plugs looked good there. I keep building it out like that now but when I started my baseline numbers were very close to what TurboII shows in his approach.
 

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What I posted above is for pump gas or E85. I mentioned if it was race fuel, C16, Q16, Methanol or equivalent I start at NA or higher to get up on converter, don't pull anything until 10psi then its 0.5*/psi to full boost. Both are safe starting points if you do your homework and you can chip away at it safely to find even more power safely reading the plugs and evaluating time slips.
 

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What I posted above is for pump gas or E85. I mentioned if it was race fuel, C16, Q16, Methanol or equivalent I start at NA or higher to get up on converter, don't pull anything until 10psi then its 0.5*/psi to full boost. Both are safe starting points if you do your homework and you can chip away at it safely to find even more power safely reading the plugs and evaluating time slips.

Assuming you're starting at about 36 degrees on something like C16.. Are you talking about a timing curve using an ice water intercooler ??
 

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Either A2W Gas or Methanol. You have to adjust base timing and what timing factor is safe for the particular combo. The main thing to learn from this is how to generate and/or spot check a map so it is consistent and doesn't have gaps, too high, too low etc. This keeps you from guessing or being so far off the curve it is super slow to tune or too high and hurts parts before you get it in a safe range. Apply numbers based on experience or good info from a trusted source to get you started. The principal is more important than the base values I use as an example. USE THE CORRECT HEAT RANGE AND READ THE PLUGS.
 

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I have seen more than one experienced racer see the strap starting to get sketchy, and fix it with a colder plug. LOL. That's not a fix.
I was really surprised at how little of the maps I use. With a loose converter, it pretty much goes straight up on column or two, and then straight over at my target boost. Might make sense to adjust the map resolution in those area lol.
 
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