timing effects on hp

About 600 if it detonates hard.
Really, it is hard to say, way too many factors involved to put a number on it.

well if i recall the gain in hp with added timing is about 20 going from 32* to 34 like on wild bill engine.but like thay said there is a lot of veriables.

Hard to say, but think about this...they guy who did my meth set up picked up 57hp on a 427 tri power vette by adding the meth. this way he could run as much timing as he could and not worry about detonation. So I think if you are talking about a degree or two not much but if you have to go from 38* to 30 or lower you drop some.

All I can add is that when we dynoed my 600-HP 440 at 32, 35 and 38 degrees total, it made the best w/ 35. HOWEVER, the differences across that 6-degree spread were not huge and couldn't be quantified in the manner which you asked.

We also had enough octane in the test fuel (50/50 93-pump and 108 leaded race gas) that more timing than optimal didn't put the engine into detonation. Running on the ragged edge of the engine's octane requirement could have a much different effect when over-timing it.

Effiecncy of the combustion chamber will also play a large roll in this. in-effecient chambers need more timing to get it done.....

As stated above there are many variables.
However, I did test this on a similar powered 440 on our "loaded" chassis dyno 2 weeks ago and discovered the following:
1. The RWHP difference between 34 degrees and 39 degrees was 35hp (+35rwhp at 39).
2. The RWHP with every degree added from 38 to 40 was only 1 RWHP per degree.
3. Retarding timing at 6580rpm from 39 to 36 increased rwhp by 3hp.

There were many other tests but I won't bore you. This was using Citgo 110 race fuel in a 12.89:1 446 w/MSD Dig7, full exhaust, no air cleaner, blah , blah....

Looking at my old chassis dyno sheets, I picked up 10+ hp-tq by going from 35 degrees to 31 w/110 trick racing fuel. Mixing 50/50 91 w/110 at the track my car is quickest around 33-34 buit not by much even up to 38 degrees.

In my opinion, timing is something that is very misunderstood, by most people. Many want to run as much as they can, because they think is makes power and that is not the case. The timing number, is simply when you light the cylinder and start the burn, nothing else. The more timing you need to run, to have enough time, to get a complete burn, really has the motor working against itself. The more before TDC you light the charge, the more that pressure is fighting the piston approaching TDC. In a perfect world, you would want a super efficient motor, that you could light off at TDC and have a complet burn, before the supposed ideal of 15* ATDC. Of course that can't happen, our engines are not that efficient yet, so we must start the burn earlier. But everyone should be concentrating on how to make their engines MORE efficient, so they need LESS timing, than trying to stuff all the timing they can in there. Even if you have an old school head design, with a not completely efficient chamber, you can still make that engine more efficient, with a modern intake, better valve job, modern cam profiles, properly tuned carbs and many other things, in the quest for maximum efficiency. These days, if your motor needs 38-40 degrees to make power, you have some really old school parts and are not even trying.

Monte

I will try to make this as short as possible the reason I asked is I apparently set my timing wrong last weekend after resetting the initial in the distributor. I didn't rev the engine past the multispark on the msd (using a real acient timing light that is self powered by the #1 plug wire only) it had alot of scatter spark. When I got home I rechecked (thanks to sixpackguts help pointing this out)and reved it past 4000 rpms and bam the scatter was gone and best I could tell the timing was at 50 deg btdc right then. So I set dist up to go fully in early on (one spring on the counterweights) and reset the timing to 35 total. And was just curious as to how much power I had lost at the track because of the timing issue. I know that it was real bad to have the timing that far advanced and I am very new at this level of racing so don't beat me up to bad for my lack of knowledge. By the way thanks for the replies they were all easy to understand.

There's just no way to quantify this. The only way you'll know is to go out again, and run #'s off of you're trap MPH. In the long run, you'll know more after this issue, so its a good thing.

Race car packages alone create too many variables to determine the best setting.For us we pick a base line timing number, for instance a Hemi we use 35 degrees and adjust up or down to find the best for the particular package.Generally we find the larger displacement and high C/R needs less timing advance.A wedge we usually start at 36 degrees and adjust from that baseline.Efficiency,induction,volume as well as cam phasing and many other factor determine total timing.To say all Hemis are at 35,all wedges are at 36 and all SBs are 38 would be incorrect but are usable baseline setting for natural aspirated engines.Engines with power adders(NO2) or pressurized(blowen or turbo) need a more consertative baseline setting.

I will probly never get to find out the difference with the 3.55s I'm going to put 4.56s in it this evening and hopefully it doesn't ran out our local rack tomorrow night. hopefully the gears get me closer to where I wanna be without any traction problems.

As mentioned, it depends on the combination.
When I first start tuning a new engine at the track, I use high octane fuel and slowly increase the total timing till the performance levels off, then usually go back to the previous setting.
If it is a pump gas engine, after setting the timing as above, I will slowly reducing the octane rating, usually by mixing pump and race gas in various ratios while putting miles on the engine. Normally a performance timing curve works fine, but sometimes, with a truck or car with low stall (operates alot below 3,000 RPM), I will have to slow down the advance curve so total timing comes all in at a higher RPM.