Re: calculating peak rpm hp
[Re: mopar dave]
#2536101
08/14/18 12:03 PM
08/14/18 12:03 PM
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Joined: Jan 2003
Posts: 14,504 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 14,504
So. Burlington, Vt.
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When you really wanna know, you dyno it.
Other than that, it’s just a guesstimate.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: calculating peak rpm hp
[Re: mopar dave]
#2536367
08/14/18 07:48 PM
08/14/18 07:48 PM
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Joined: Mar 2009
Posts: 2,464 Sydney,Australia
tex013
top fuel
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top fuel
Joined: Mar 2009
Posts: 2,464
Sydney,Australia
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Yeah, i understand. Just looking for a guess anyway. Not sure where to shift this 511 at once i get to the track. 330cc heads and a 270@50 solid cam. Seems to pull hard to upper 6000 range. Thanks Solid roller or flat tappet ? For what it is worth , my 505 with a 272@050 solid flat tappet .5400ish converter , 4.1 gear 28"radial . Chassis dyno always showed peak HP at converter stall(5100 footbrake vert) , but motor pulled to 6500 without any drop off With CNC source heads , Victor and 4150 prosystems carb I shifted at 6000 . 10.50s . I tried a little more not big gain , but it never seemed to give up under 7000 with either converter . With TF270 heads , bigger tbrake vert , Super Victor and 1050 dominator . I only ran this a couple times . BUT shifting at 6000 it didn't fall back onto converter , shift light stayed on @6000 - so stall increased . 10.25@130 . I believe with the bigger heads it wanted a higher shift probably 64-6600 which would have allowed rpm drop back to converter on shift That is now to be another day , due to block issues . Why the low shift ? It ran the numbers I wanted and was doing it easily at low stress . Tex
Last edited by tex013; 08/14/18 07:50 PM.
New best ET 10.259@129.65 . New best MPH 130.32 Finally fitted a solid cam, stepped it up a bit more 3690lbs through the mufflers New World block 3780lbs 10.278@130.80 . Wowser 10.253@130.24 footbraking from 1500rpm Power by Tex's Automotive
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Re: calculating peak rpm hp
[Re: mopar dave]
#2536665
08/15/18 11:30 AM
08/15/18 11:30 AM
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Joined: Jan 2003
Posts: 11,718 Portage,michigan
B3422W5
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 11,718
Portage,michigan
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Not rocket science. Just try shifting it at different rpm and see what makes it ET best. Try it at 66, 68 and 7000 and see what it likes best.
69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight 418 BPE factory replacement headed stroker, 565 lift solid cam Best so far, 10.40 @127 1/4 1.41 best 60 foot 6.60 at 103.90 1/8
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Re: calculating peak rpm hp
[Re: B3422W5]
#2536730
08/15/18 01:33 PM
08/15/18 01:33 PM
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Joined: Aug 2003
Posts: 43,218 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,218
Bend,OR USA
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Not rocket science. Just try shifting it at different rpm and see what makes it ET best. Try it at 66, 68 and 7000 and see what it likes best. I start with 500 RPM increments and the go to 100 after finding the highest and lowest shift points, especially on putting any new parts in the car, converter, cam, jetting and so on
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: calculating peak rpm hp
[Re: mopar dave]
#2536788
08/15/18 03:34 PM
08/15/18 03:34 PM
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Joined: Jan 2003
Posts: 11,718 Portage,michigan
B3422W5
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 11,718
Portage,michigan
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For sure, but thought i might try short shifting at 6000 to start. Then 6500 and go from there. Any such way like that will ultimately find out what i likes best. Love ya man, but frankly you make things more involved and harder than anybody that has ever posted on here... lol
69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight 418 BPE factory replacement headed stroker, 565 lift solid cam Best so far, 10.40 @127 1/4 1.41 best 60 foot 6.60 at 103.90 1/8
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Re: calculating peak rpm hp
[Re: mopar dave]
#2536813
08/15/18 04:46 PM
08/15/18 04:46 PM
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Joined: Jan 2003
Posts: 11,718 Portage,michigan
B3422W5
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 11,718
Portage,michigan
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Just who i am. I leave no stone unturned if possible. I like the opinion of others as well. Wheres the harm and besides, this site would pretty slow if no one was asking questions simple or not. Never said there was any harm in it, but in this thread( like some others) you answered your own question. ....... try different rpms till it runs the best...... way early in the thread. I suspect you already knew that to be the answer. Thats my only reason for saying what i said
69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight 418 BPE factory replacement headed stroker, 565 lift solid cam Best so far, 10.40 @127 1/4 1.41 best 60 foot 6.60 at 103.90 1/8
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Re: calculating peak rpm hp
[Re: B3422W5]
#2536864
08/15/18 07:31 PM
08/15/18 07:31 PM
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Joined: Feb 2005
Posts: 20,184 PA.
pittsburghracer
"Little"John
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"Little"John
Joined: Feb 2005
Posts: 20,184
PA.
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For sure, but thought i might try short shifting at 6000 to start. Then 6500 and go from there. Any such way like that will ultimately find out what i likes best. Love ya man, but frankly you make things more involved and harder than anybody that has ever posted on here... lol WOW 😮. That wasn’t a very cool thing to post. LOL.
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27
Livin and lovin life one day at a time
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Re: calculating peak rpm hp
[Re: mopar dave]
#2536868
08/15/18 07:36 PM
08/15/18 07:36 PM
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Joined: Mar 2009
Posts: 2,464 Sydney,Australia
tex013
top fuel
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top fuel
Joined: Mar 2009
Posts: 2,464
Sydney,Australia
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nothing wrong with checking others opinion/experience , if only to confirm you are heading in the right direction .
Tex
New best ET 10.259@129.65 . New best MPH 130.32 Finally fitted a solid cam, stepped it up a bit more 3690lbs through the mufflers New World block 3780lbs 10.278@130.80 . Wowser 10.253@130.24 footbraking from 1500rpm Power by Tex's Automotive
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Re: calculating peak rpm hp
[Re: mopar dave]
#2537050
08/16/18 08:55 AM
08/16/18 08:55 AM
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Joined: Jan 2005
Posts: 4,243 Charlotte, North Carolina
sgcuda
master
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master
Joined: Jan 2005
Posts: 4,243
Charlotte, North Carolina
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Ask any questions you like. That's how we all learn. There are never stupid questions, only stupid people. Lol! Some people on here make comments about the repetition of questions. Sometimes we forget that people come and go off of this site all of the time. What people need answers to aren't in the first couple of pages listed and we all know too well how wonderful the SEARCH function works on here. My old combo with a 262/266 lift on my 440 liked a 6,800 rpm shift point. Car would slow down with a 6,500 or 7,000 shift. You'll find the sweet spot real quick.
Last edited by sgcuda; 08/16/18 08:55 AM.
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Re: calculating peak rpm hp
[Re: mopar dave]
#2537060
08/16/18 09:57 AM
08/16/18 09:57 AM
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Joined: Sep 2014
Posts: 4,457 Washington
madscientist
master
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master
Joined: Sep 2014
Posts: 4,457
Washington
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FWIW once you establish your shift speed, you may want to try changing RPM for just one gear. For example, you may be able to run the 2-3 shift out a bit more than the 1-2 shift. Or it could be the opposite. It's not always that the engine wants to be shifted at the same RPM at every shift change.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: calculating peak rpm hp
[Re: mopar dave]
#2537104
08/16/18 12:02 PM
08/16/18 12:02 PM
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Joined: Oct 2007
Posts: 4,209 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,209
New York
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you may want to try changing RPM for just one gear. For example, you may be able to run the 2-3 shift out a bit more than the 1-2 shift. Or it could be the opposite. It's not always that the engine wants to be shifted at the same RPM at every shift change.
This^^^ All modern transmission have "ratio progression" in which the RPM % drop on shift is widest on the 1-2, and closes up as you reach final drive.
Boffin Emeritus
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Re: calculating peak rpm hp
[Re: madscientist]
#2537220
08/16/18 03:36 PM
08/16/18 03:36 PM
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Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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FWIW once you establish your shift speed, you may want to try changing RPM for just one gear. For example, you may be able to run the 2-3 shift out a bit more than the 1-2 shift. Or it could be the opposite. It's not always that the engine wants to be shifted at the same RPM at every shift change. A couple of Stock Eliminator people I know shift their 1-2 200-300 RPM lower than their 2-3. Never tried it on my junk, simply cuz I position the tach "straight up" at the RPM where I shift for easy reference. Also, I don't use a shift light any more; I was always late on the shift when waiting for the light at the specified RPM. I'm more consistent w/ the approach above. Regardless, I was never aware of any major shift lag time that caused my actual shifts' RPMs to be so much higher like some of you said. I'd like some type of data logger or playback tach to see what's happening across the whole pass, though.
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Re: calculating peak rpm hp
[Re: BradH]
#2537228
08/16/18 03:41 PM
08/16/18 03:41 PM
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Joined: Feb 2005
Posts: 20,184 PA.
pittsburghracer
"Little"John
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"Little"John
Joined: Feb 2005
Posts: 20,184
PA.
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A powerglide kinda simplifies this option
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27
Livin and lovin life one day at a time
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Re: calculating peak rpm hp
[Re: mopar dave]
#2537290
08/16/18 05:43 PM
08/16/18 05:43 PM
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Joined: Oct 2007
Posts: 4,209 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,209
New York
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You may also see different converter slippage on different shifts: the 1-2 has more torque, but the 3-4 is against higher load. Once you find what works for you, the reason sort of matters less...
Boffin Emeritus
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Re: calculating peak rpm hp
[Re: mopar dave]
#2537334
08/16/18 07:17 PM
08/16/18 07:17 PM
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Joined: Jan 2003
Posts: 7,491 Minnesota
Hemi_Joel
master
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master
Joined: Jan 2003
Posts: 7,491
Minnesota
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At the pure stock drags, where you weren't allowd to add a tach, they use to say "when the fender starts to lay down, SHIFT"
[img]http://i.imgur.com/boeexFms.jpg[/img]31 Plymouth Coupe, 392 Hemi, T56 magnum RS23J71 RS27J77 RP23J71 RO23J71 WM21J8A I don't regret the things I've done. I only regret the things I didn't do. "Wise men talk because they have something to say; fools because they have to say something. ~ Plato"
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