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Bracket Talk Bracket Talk Forum Tech Talk - by Abruzzi How does ignition timing effect the runGo | New | Find | Notify | Tools | Reply | |
| How does ignition timing effect the run | Login/Join |
| DRR Sportsman |
I just got a grid. How does timing manipulation effect the run? From what I have read high timing gives you low end, and low timing gives you top end. I hear about top dragster and top sportsman guys pulling timing at the hit to stop tire shake, but then bring it all back in throughout the run. If the low timing = top end, and high timing = bottom end theory is true..... wouldn't bringing in full timing throughout the run actually hurt ET overall? If this theory is true, in my mind, you should leave at the highest level of timing possible without tire shake, and then pull it throughout the run. Last question.....Is there a difference as far as ignition timings effect when you run Gas or Methanol? I appreciate any responses here. | ||
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DRR Sportsman |
Timing manipulation is usually more about getting the chassis or tire under control. If your engine is tuned spot on then pulling a degree or 2 on the big end will SOMETIMES put mph in the car. I have a 450 bracket dragster on MFI and i actually put timing in the engine at a certain rpm to help compensate the injection going fat, kinda like a red neck high speed lean out. Jeremiah Hall | |||
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| DRR Sportsman |
Do you happen to know why this is? Specifically, why does retarded timing run harder top end than advanced timing. I always assumed that you wanted more advanced timing with higher RPM. | |||
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DRR Top Comp |
I know one thing from lots of Dyno time and track runs. Many people run way more timing than needed. On my 454 SBC was told to run it at 38* timing and I did for a few months. Then I dynoed my motor and found it likes it best at 28*-30*Plus it is easier on the rotating assembly when you are not firing it off as early. Now the horsepower and ET change was not much at all but every little bit helps. If I remember right it was less than 15 Hp more at 28* and that is not much on the track. Maybe what? .01? On my motor when I drop it lower than 28* it started losing power. One thing to keep in mind is if you are running too much timing you can get away with being a little fat on your tune up and plugs still still look good. So it could be a little misleading there. That is where some good dyno sessions can really help your program. I use Joe at Cen-Tex Dyno and he has been a huge help. I live in Dallas Fort Worth area and there are many dynos close but I drive over 3 hours each way to Cen-Tex because he is good at what he does and familiar with mechanical fuel injection. I really like the grid and wish I could run one in my class. I often run Nostalgia Index racing and it would be great if I could pull some timing out at the hit on marginal tracks or to kill some ET to run the number and still have good MPH at finish line. So if you know the baseline from dyno testing the Grid could possibly help you even more. https://postimg.cc/gallery/np3zpruo/ "Dunning-Kruger Effect" -a type of Cognitive bias where people with little expertise or ability assume they have superior expertise or ability. This overestimation occurs as a result of the fact that they do not have enough knowledge to know they don't have enough knowledge. Before you argue with someone ask yourself, "Is this person mentally mature enough to grasp the concept of a different perspective?" If not there is no point to argue. 4X NE2 CHAMPION. 2020 TDRA NE2 Champion | |||
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| DRR Sportsman |
I agree with this actually. What i have found is with conventional headed chevys, sbc and bbc, that when they are tuned right, will run best going down the track between 32-34. Usually when a combo needs 36+ there is some fuel tuning left on the table. Jeremiah Hall | |||
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| DRR Sportsman |
Is that on Methanol? I have heard it likes more timing than gas | |||
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| DRR Sportsman |
Mine is methanol, and methanol usually likes LESS timing than gas. Jeremiah Hall | |||
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DRR S/Pro |
My engine wanted the same timing on methanol as gas. I also agree most run more timing than needed. Several years back, when I had the engine on the dyno, when I told my engine guy that the timing should be around 34, he laughed and said it should be in the 38 range. When we tried it, it lost power all the way through. This was also backed up on the track. I made a timing curve based on the dyno numbers and where the engine made peak power at each timing point. In the car, there was no discernable gains in ET. Bill Simpkins 74 Nova SBC 406 3240 pounds Speierracing heads 60 1.27 (10/16) 1/8 6.03@111 (10/16) Best 9.87@131 on the rev limitor 1 Feb 2013 nova quarterpanelview wheelie FTI Converter www.speierracingheads.com | |||
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| DRR Sportsman |
So with the given information say your trying to run on a mediocre track prep. Figuring everything is tuned properly and you make max power at 34*. Would a proper setup be Leave at 28* to control the rear tire (knock some low end out until say 60') then ramp up to 34* for majority of the run, then say the last 1 second of the run go back to 32*??? | |||
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| DRR S/Pro |
Its definitely going to be a trial and error to see what your car wants. Also on my car, pulling timing on the top end in my car made no decernable difference. Bill Simpkins 74 Nova SBC 406 3240 pounds Speierracing heads 60 1.27 (10/16) 1/8 6.03@111 (10/16) Best 9.87@131 on the rev limitor 1 Feb 2013 nova quarterpanelview wheelie FTI Converter www.speierracingheads.com | |||
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| DRR Sportsman |
I would think this type of thing would make more difference in a fast door car, or dragster before it would make a difference in your average bracket car. When I say difference I'm thinking something noticeable like 1-2 mph. But I have no clue what I'm talking about on this subject. | |||
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| DRR Pro |
Now that you have the ability to manipulate timing and other items with MSD 7730 Grid, you can see what your engine (and you) like best. No right way or wrong way, just your way. | |||
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DRR S/Pro |
One thing that isn’t being discussed here is the efficiency of the chamber. You can’t really make blanket statements about timing without considering this in my opinion. I have a set of older heads and the chamber shape is not as efficient as a newer set would be. Now when you talk about where you are pulling or adding timing it is the same for either. It’s just different quantity wise for different chambers even on the same size engines. JMO ____________________________ 2017 and 2018 Osage Casinos Tulsa Raceway Park No-Box Champion 2018 Div4 Goodguys Hammer award winner | |||
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| DRR Top Comp |
Timing - Where does it make the MOST cylinder pressure after TDC. The End | |||
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| DRR Top Comp |
My heads are AFR 235 and I am on Methanol. A more efficient chamber may need less timing than even the 28*-30* that I run. My new motor has really good 18* heads and it may need less timing. To kill some ET I drop the timing to 24* or 26*. Now on my car and your mileage may vary there is little ET difference from 28* to 38* timing. But there is a few more ponies at 28 and I feel it is easier on motor than 38* so that is where I run mine. So if I was running 38* and pulled 8* out for 1.2 seconds or something like that it would not make any difference at all. None. Now if my baseline is 28* and I pull 8* out for that same time it would make a significant difference. That is where I think the Grid is a good deal if you are allowed to run them. You could also pull a few degrees out on the shift if needed. https://postimg.cc/gallery/np3zpruo/ "Dunning-Kruger Effect" -a type of Cognitive bias where people with little expertise or ability assume they have superior expertise or ability. This overestimation occurs as a result of the fact that they do not have enough knowledge to know they don't have enough knowledge. Before you argue with someone ask yourself, "Is this person mentally mature enough to grasp the concept of a different perspective?" If not there is no point to argue. 4X NE2 CHAMPION. 2020 TDRA NE2 Champion | |||
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DRR Trophy |
Buddy if you look at everything these people are saying, you either need to spend a few days testing at the track in stable weather or spend some money on dyno time. I believe you are over thinking the issue. I understand you want the most out of your combo but futzing over pulling this or adding that during a run is just over doing it. If your chassis is not happy where its at work on the launch timing or RPM or shocks. If your index racing and you need to slow to hit the index then puling timing at the end to achieve your index is where you want to be working it at. If you need to settle it down at the hit to get it moving then work it there. Now if your heads up first to the line and your squeezing every bit of power you have then may look into what your are thinking but there are lots of other places to look for HP. If your bracket racing set it up where its happy and don't touch it. The best advise I got from an old very successful racer was use that old KISS method and go have fun running the car. | |||
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DRR Pro |
Not true, it's combo dependent. My stuff on gas, in Denver, likes 31-32* max for best performance....On alky it wants 36*. At sea level on gas 28* was best...On alky it wanted 32-34*. All depends on engine setup, and less timing on alky is not always the case. Most I've seen wanted more than gas. Mark Goulette Owner/Driver of the Livin' The Dream Racing dragster www.livinthedreamracing.com "Speed kills but it's better than going slow!" Authorized Amsoil Retailer | |||
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| DRR Pro |
If you are just taking MSD Grid 7730 out of the box you might want to read this if you are new to digital. https://drr.infopop.cc/eve/foru...12/m/5891021504/p/11 Pay attention to wiring installation. Unlike analog, Digital likes clean signals for everything. Crank trigger is better than distributor trigger when using digital ignition imo. When activating relays with Grid, the ones with a diode across coil are my preference. I (me) diode everything attached to Grid that has a coil to include the transbrake and linelock solenoid. If replacing present analog with digital, program it the same as known analog and work from this baseline. | |||
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| DRR Sportsman |
That could be true on the hill that you race on, but down in here in corn country, most of the time we use less timing than gas. Jeremiah Hall | |||
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DRR Sportsman |
I have a small block, small tire car on alcohol that runs 6.40's-50s. I run my car at 38 degrees and pull 2 degrees at the hit and ramp it back in the first second of the run. Then I pull 2 degrees in high gear and cross the 1/8th at 36*. As I pull 2* in high gear, my O2's raise .2-.3 on the graph. If I raced on a marginal track, I would adjust the shocks and could pull more timing at the hit with a coulpe key strokes if needed. 72 Nova "Hooptie" | |||
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Bracket Talk Bracket Talk Forum Tech Talk - by Abruzzi How does ignition timing effect the run
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