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Discussion Starter #1
Taking my car to the dyno tomorrow, TI Dyno in Ashtabula, OH. I've been losing MPH the past few years at the dragstrip and thought it might be good to see if a pro can coax some of my power back. I used to trap 107-108, even hit 109 in perfect air. Anymore, Im barely hitting 106. I did upgrade the valve springs this past winter, complete new exhaust from headers to tailpipes (now 3" w/ Xpipe), COP ignition. Should be fun!

-Dave

20200804_182229.jpg TuneInfo.JPG
 

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Taking my car to the dyno tomorrow, TI Dyno in Ashtabula, OH. I've been losing MPH the past few years at the dragstrip and thought it might be good to see if a pro can coax some of my power back. I used to trap 107-108, even hit 109 in perfect air. Anymore, Im barely hitting 106. I did upgrade the valve springs this past winter, complete new exhaust from headers to tailpipes (now 3" w/ Xpipe), COP ignition. Should be fun!

-Dave

View attachment 693659 View attachment 693660
Good luck, hope you find some hp lurking in there!
 

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I would say if you could make a intake to take air from the left or right of the car in front of the inner fender, behind the rad support you would see a gain. Use preformed plastic tubing, like a builder kit such as this. Don't use one that the bends are soft silicone hose.

 

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Discussion Starter #5
Dyno day complete -- good and bad. The good part turned out to be that it was already tuned really well, which was mostly me. It was pretty solid went I went there, but was hoping there would be more that could be tweaked out. The bad part is there wasn't much tuning gain to be had.

I had this setup on the dyno prob back in 2015-2016, although back then, I had open headers, 3.55 gears, i was running MS2 with my 6AL/distributor, and a different converter. Today, I have 3" w/ Xpipe full exhaust, 3.73s, MS3X wth COP ignition, new beehive valve springs.

316 HP @ 5500, 322TQ @ 4800. 12.5 AFR at WOT, 34* timing. I was really hoping for something a little better than that. I was really hoping to get this combo into the 11s, or even just 110mph+, but I don't think it's gonna happen. They suggested maybe the next place to look would be torque converter. It's just a $300 Summit 10". I've had good experience with Edge Racing converters, so I may order up one of those.


-Dave
 

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Dyno day complete -- good and bad. The good part turned out to be that it was already tuned really well, which was mostly me. It was pretty solid went I went there, but was hoping there would be more that could be tweaked out. The bad part is there wasn't much tuning gain to be had.

I had this setup on the dyno prob back in 2015-2016, although back then, I had open headers, 3.55 gears, i was running MS2 with my 6AL/distributor, and a different converter. Today, I have 3" w/ Xpipe full exhaust, 3.73s, MS3X wth COP ignition, new beehive valve springs.

316 HP @ 5500, 322TQ @ 4800. 12.5 AFR at WOT, 34* timing. I was really hoping for something a little better than that. I was really hoping to get this combo into the 11s, or even just 110mph+, but I don't think it's gonna happen. They suggested maybe the next place to look would be torque converter. It's just a $300 Summit 10". I've had good experience with Edge Racing converters, so I may order up one of those.


-Dave
Well I would look at it this way, you just tested on a dyno which is not a race track The only thing I look at are the hp pick ups from changes not actual overall numbers. Never thought my 406 was going to run good times with the Vortec heads but I got a real surprise this year and you may also. If you combo timing was at 34° run that at the track and then try 38-40° the car may pick up. The best 10" converter I have used so far has been the Jeg's 10" XHD 4100 stall they say it flashes to 4100 and it did just that with both my 406 and my 468, cheap too.
 

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For a 383 that is street driven and through an automatic that is pretty good. The factory LS6 chevelle was like 290 hp at the tire. You are probably putting out 425 motor hp. You have good track times given the power you got. A higher stall converter might work to get you there depending on what you have now. The overdrive transmission gives you some flexibility.
 

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Did they try leaner AFR to see if it made more power?
When being driven, I would put money on that it would be faster with more cold air instead of hot air coming through the radiator
 

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As above I'd put an intake tube on it to get incoming air out from behind the radiator. I have an LS in mine but you could probably get by with the same setup. I purchased a $55 2000ish silverado cold air intake off ebay. It sticks the headlight in front of the fenderwell right behind the headlights. It's not the best looking but I have cold air coming in around my headlights. You could put the throttle body part in a vise and oval it to match your TB.

I can datalog the incoming air temp (IAT) sensor and see that I'm right at ambient driving around. It does get a little warm coming to a stop but I don't have the air filter sealed off from the engine bay at all. I know you don't have this problem but my factory tune would pull max 12 degrees timing as the incoming air would rise in temp, engine would fall flat on it's face.

Imagine your car on the dyno with the hood closed, you'd loose HP fast. ;)
 

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Dyno day complete -- good and bad. The good part turned out to be that it was already tuned really well, which was mostly me. It was pretty solid went I went there, but was hoping there would be more that could be tweaked out. The bad part is there wasn't much tuning gain to be had.

I had this setup on the dyno prob back in 2015-2016, although back then, I had open headers, 3.55 gears, i was running MS2 with my 6AL/distributor, and a different converter. Today, I have 3" w/ Xpipe full exhaust, 3.73s, MS3X wth COP ignition, new beehive valve springs.

316 HP @ 5500, 322TQ @ 4800. 12.5 AFR at WOT, 34* timing. I was really hoping for something a little better than that. I was really hoping to get this combo into the 11s, or even just 110mph+, but I don't think it's gonna happen. They suggested maybe the next place to look would be torque converter. It's just a $300 Summit 10". I've had good experience with Edge Racing converters, so I may order up one of those.


-Dave
That's interesting that your "only" getting 316rwhp and running low 12's. There was another thread just a few weeks ago and the discussion was how these cars/engines seem to run a lot better than the dyno #'s would lead you to believe. For example, how are these stock Camaro's and Mustangs seemingly dynoing in low 400's and are only hitting low 12's?
 

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I think the reason the new Camaros / Mustangs (which are similar weight to Chevelle) are running low 12s is probably traction but look at the mph they are doing probably 115+. A stock C6 Z06 usually dynos at 435 rwhp and traps 125 mph in the mid 11s off the showroom floor. Now that car weighs 3,200 pounds full tank of gas so a little lighter. His mph is very similar to stock LS6 Chevelle (290 rwhp) which was like 106-108 mph. I think he is doing low 12s because he probably has pretty good traction and the 700r has an awesome launching first gear (3.0 to one or so).
 

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"it was already tuned really well, which was mostly me"

Living proof, "seat of the pants" dyno is the ONLY tuning device that actually finish TUNES the power trqain, NOT an engine, or run on dyno. Dyno's are GREAT development tools, dismal final tune tools, exactly like dry flow benches.
 

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Discussion Starter #13
So, just to follow this up.. I was at the dragstrip last night and ran 12.59, 12.54 in time runs, and 12.62 in my 1st round elimination, all between 106.1-6 mph. DA was in 2000-2100 range, track elevation ~1200ft. I am losing a little as I'm having to lift a little for my 1-2 shift (trans issue), shifting at 6000 rpm, hitting the stripe at 5500. 60ft times 1.71, 1.68, 1.72, yes traction is good with MT ET Street R compound, 275-50-15.

As for a cold air intake tube.. I had one, I tested it on the same day I ran my best ET ever -- 12.18 @ 109 in 40* -69ft DA air. WITH my cold air intake, I went 107.5 MPH. Without it, I went 109. Maybe my CAI is too small at only 3.5". And while it was no longer pulling from right behind the radiator, it was still under-hood air. But those runs were on the same day, no other changes. I have datalogs that will show IAT, but they're on my other laptop right now.

No -- we didnt try leaner to see if would make more power.. I wish we would've done that. I'm targeting 12.5 AFR, so maybe try 12.8? 13.0?

I've tested the spark timing previously. GM spec for this engine is 32, so I tested 32/34/36. 34 produced best MPH at the dragstrip. My first trip to dyno a couple weeks later confirmed that. I'm going to try a 1 step colder plug, an ACdelco R42LTS, for next week. That wouldn't change the timing requirement would it?

The torque converter is my weak link. It's just a Summit 10". It has served its purpose, sorta, but time to get something better from Edge Racing and see what kind of improvement that generates. The 700r4 combo IS really nice. The car launches like crazy and I still run down the freeway 75-80 mph under 3000 rpm.

My ultimate goal is to either get in the 11s or go 110+ mph. At 3600lbs (w/me), that might be a bit optimistic.

Thanks for all the responses.

-Dave
 
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On my particular combo, 13.0 afr at full throttle vs 12.5 was worth 2 mph. Therefore don't just shoot for a number, but go by the mph. MPH tells the hp. If you pick up speed you gained power.
 

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So, just to follow this up.. I was at the dragstrip last night and ran 12.59, 12.54 in time runs, and 12.62 in my 1st round elimination, all between 106.1-6 mph. DA was in 2000-2100 range, track elevation ~1200ft. I am losing a little as I'm having to lift a little for my 1-2 shift (trans issue), shifting at 6000 rpm, hitting the stripe at 5500. 60ft times 1.71, 1.68, 1.72, yes traction is good with MT ET Street R compound, 275-50-15.

As for a cold air intake tube.. I had one, I tested it on the same day I ran my best ET ever -- 12.18 @ 109 in 40* -69ft DA air. WITH my cold air intake, I went 107.5 MPH. Without it, I went 109. Maybe my CAI is too small at only 3.5". And while it was no longer pulling from right behind the radiator, it was still under-hood air. But those runs were on the same day, no other changes. I have datalogs that will show IAT, but they're on my other laptop right now.

No -- we didnt try leaner to see if would make more power.. I wish we would've done that. I'm targeting 12.5 AFR, so maybe try 12.8? 13.0?

I've tested the spark timing previously. GM spec for this engine is 32, so I tested 32/34/36. 34 produced best MPH at the dragstrip. My first trip to dyno a couple weeks later confirmed that. I'm going to try a 1 step colder plug, an ACdelco R42LTS, for next week. That wouldn't change the timing requirement would it?

The torque converter is my weak link. It's just a Summit 10". It has served its purpose, sorta, but time to get something better from Edge Racing and see what kind of improvement that generates. The 700r4 combo IS really nice. The car launches like crazy and I still run down the freeway 75-80 mph under 3000 rpm.

My ultimate goal is to either get in the 11s or go 110+ mph. At 3600lbs (w/me), that might be a bit optimistic.

Thanks for all the responses.

-Dave
Put a Jeg's XHD converter in the car. My 4100 stalled one was spot on and have used it twice with 2 different engine combo's. I really like it and the price for what you get is killer.
 

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Discussion Starter #16
Put a Jeg's XHD converter in the car. My 4100 stalled one was spot on and have used it twice with 2 different engine combo's. I really like it and the price for what you get is killer.
I've had good results with Edge Racing converters. Called them up yesterday and placed an order. 5 business days, plus ground shipping from CA to OH. With some luck, I might have it installed in time for the last Wednesday night of the season!

On my particular combo, 13.0 afr at full throttle vs 12.5 was worth 2 mph. Therefore don't just shoot for a number, but go by the mph. MPH tells the hp. If you pick up speed you gained power.
That's quite a difference. I'll have to experiment with that some.

-Dave
 
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I've had good results with Edge Racing converters. Called them up yesterday and placed an order. 5 business days, plus ground shipping from CA to OH. With some luck, I might have it installed in time for the last Wednesday night of the season!



That's quite a difference. I'll have to experiment with that some.

-Dave
Edge is good stuff.
 
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