Tuning, is it really all that??

[TC]

There is a lot of talk about tuning a motor for maximum power output, but how much of this tuning is really making the power over what the motors going to make anyway. Example, if lets say your motor won't run with anything less than 28 degrees of advance and it makes it best power at 38 degrees of advance how much power are you losing by running it at 28 degrees, are we talking 10hp, 20hp, 50hp?? And that goes for AFR's to, how much power are you losing by running the motor to rich or in that case to lean and how is the timing going to play a factor in this.

So if your motor makes 450hp with optimum AFR's and timing, how much power will you lose by retarding the timing 10 degrees and richening up the fuel mixture??

Now these are extreme conditions, how about the guy that is only a couple degrees off and has his AFR's pretty close to, how much is the gain then, 5hp??

[SpiderGearsMan]

Re: Tuning, is it really all that??

need to retard it once you get rolling
I ran a two step with multi step retard for hitting the bottle

[dieselgeek]

Re: Tuning, is it really all that??

There is a lot of talk about tuning a motor for maximum power output, but how much of this tuning is really making the power over what the motors going to make anyway. Example, if lets say your motor won't run with anything less than 28 degrees of advance and it makes it best power at 38 degrees of advance how much power are you losing by running it at 28 degrees, are we talking 10hp, 20hp, 50hp?? And that goes for AFR's to, how much power are you losing by running the motor to rich or in that case to lean and how is the timing going to play a factor in this.

So if your motor makes 450hp with optimum AFR's and timing, how much power will you lose by retarding the timing 10 degrees and richening up the fuel mixture??

Now these are extreme conditions, how about the guy that is only a couple degrees off and has his AFR's pretty close to, how much is the gain then, 5hp??

this is a great post!! I've been thinking the same thing myself lately.


I can answer the timing question with an example. We had a 387" pump gas engine making around 640hp on a DTS dyno recently. Best power timing was 30 degrees total advance. In the ten degrees preceeding that 30 degrees, there was an average HP gain of 10hp per degree of timing. Significant.

However, the AFRs on that engine almost didn't matter. It made the MOST power when we had the LEAST control of AFRs, and the ugliest AFR graphs.


I'm quite confident you cannot apply this information across the board. If an engine doesn't respond much to timing, it means that there is cylinder-to-cylinder imbalance in timing and/or AFRs.

Anyways, the question should be "how much is it worth to grab that last couple HP"

[nosnerd]

Re: Tuning, is it really all that??

rewind back to 1998...bbc 555, dart 320s,dart tunnel ram and a nitrous cam with 285/301 on 116lsa..

771hp on second pull...wtf? we were scratching our heads..what happened?since we were going to do nitrous runs that day...me,wanting to do well, had already installed the -11 plugs (wanting to save time =they were 2 1/4 headers)the night prior.....that cost us 52HP!!!over the NA plugs..we ended up with -10s on the juice.

the nova:,522 cubes,14:1 CR...4 hp from 88s to 90s...but a cleaner curve..34 or 36 timing...like 4 hp...38...i was going a step back...

on a different note,istrongly believe that the incorrect converter can make or break a combo ,and that sorting out the chassis will reap better results...

i am not one to load a motor to chase 10 hp...i had my motor sorted out to my liking in 5 runs..

[IRONHEAD]

Re: Tuning, is it really all that??

some of the record runs where down on power.
just enough to make everything right with the world.. and not overpower the track and not go into tire shake..
peak is nice, but the curve is better

[TheSilverBuick]

Re: Tuning, is it really all that??

Thanks Jeff! That is just the bedtime story(video) and lullaby I needed before going to bed tonight Dang that thing revvs quick.

I included shots of the VE table just for you Randal, so you can see what the VEs look like on an engine that idles at 4 or 5 inches of vacuum... it's ridiculous (to me) that this thing even runs at all.

The biggest accomplishment here is the part throttle behavior. Unbelievably hard to get it "just right" (in certain areas of the map, a 2% change in fuel will kill a set of plugs). It's tough to make this engine "driveable" - definitely the most challenging tune I've ever come across. However, taking our time, we have been able to make it behave enough for street use.

I'm still dumbfounded by Jeff's ability to look at a spark plug, suggest a TINY change in both fuel and timing, and pick up power. The last change he requested, after I'd gotten as close as I can using AFRs and measured wheel power, was one click on the VEtable - that's .3% fuel difference - and 1 degree of timing - picked up 19whp. O2 sensors and dynos will never beat reading plugs for finding the perfect tuneup, I'm convinced.

I'd say it's important if you want to win.

[IRONHEAD]

Re: Tuning, is it really all that??

Thanks Jeff! That is just the bedtime story(video) and lullaby I needed before going to bed tonight Dang that thing revvs quick.

I included shots of the VE table just for you Randal, so you can see what the VEs look like on an engine that idles at 4 or 5 inches of vacuum... it's ridiculous (to me) that this thing even runs at all.

The biggest accomplishment here is the part throttle behavior. Unbelievably hard to get it "just right" (in certain areas of the map, a 2% change in fuel will kill a set of plugs). It's tough to make this engine "driveable" - definitely the most challenging tune I've ever come across. However, taking our time, we have been able to make it behave enough for street use.

I'm still dumbfounded by Jeff's ability to look at a spark plug, suggest a TINY change in both fuel and timing, and pick up power. The last change he requested, after I'd gotten as close as I can using AFRs and measured wheel power, was one click on the VEtable - that's .3% fuel difference - and 1 degree of timing - picked up 19whp. O2 sensors and dynos will never beat reading plugs for finding the perfect tuneup, I'm convinced.

I'd say it's important if you want to win.

yup.
but is your buick a race car ? nope.
neither are mine, I will not miss that peak, cause if I did a carb still makes more

[TheSilverBuick]

Re: Tuning, is it really all that??

yup.
but is your buick a race car ? nope.
neither are mine, I will not miss that peak, cause if I did a carb still makes more

As I said, it's important if you want to win. In my case, I'm happy to drive my cars.

[squirrel]

Re: Tuning, is it really all that??

>10k miles/year = win

[TheSilverBuick]

Re: Tuning, is it really all that??

>10k miles/year = win

Haha, Ladies and Gentlemen, Mr. Leaving Horsepower On the Table himself :D Keeps things reliable

[KeithTurk]

Re: Tuning, is it really all that??

I'm really looking forward to the results from Engine masters...... does EFI really make a difference?

Scott??? and can we figure out a way to include Driveablity into the Fray?

[A/Fuel]

Re: Tuning, is it really all that??

I'll get in on this...
My question is, why not set the engine on kill and control it with timing.....I don't race dyno's.
What I do is make it simple.
We ran a 5.36 last weekend and won the race doing just that.
When I test, I'm looking at clutch weight, and fuel curve....I'll get the timing down when I see the track I'm running on.

[purplecobra]

Re: Tuning, is it really all that??

Interesting question but why leave the AFR's off? If you are looking for a safe tune then back off a few degrees of timing but poorly adjusted AFR's will make for a driveability headache. When I was tuning cars at my old shop I did not tune for peak power but safe power levels that would live.

[A/Fuel]

Re: Tuning, is it really all that??

Interesting question but why leave the AFR's off? If you are looking for a safe tune then back off a few degrees of timing but poorly adjusted AFR's will make for a driveability headache. When I was tuning cars at my old shop I did not tune for peak power but safe power levels that would live.

The more I think about it, it's a silly question, to me anyway.

[Barry Donovan]

Re: Tuning, is it really all that??

However, the AFRs on that engine almost didn't matter. It made the MOST power when we had the LEAST control of AFRs, and the ugliest AFR graphs.


I'm quite confident you cannot apply this information across the board. If an engine doesn't respond much to timing, it means that there is cylinder-to-cylinder imbalance in timing and/or AFRs.Anyways, the question should be "how much is it worth to grab that last couple HP"

I am glad to read that from more a pro than I.

There is 50 years of engines with every different length 2 dollar plug wire shipped that way than can shake a fist at.

unbelievable. Then there is the EGR stuff and cats... numbers just don't freakin matter sometimes.