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Disappointment at the dyno
#1628800
06/04/14 07:34 PM
06/04/14 07:34 PM
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Joined: Jan 2005
Posts: 223
California
70Drop
OP
enthusiast
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OP
enthusiast
Joined: Jan 2005
Posts: 223
California
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Hi,
It's been a while. I'm finally getting serious with my Duster street/strip car. I had it on the dyno and was unhappy with the results (see dyno sheet attached to the next post). The car has run a best 11.26 @ 121 mph. Here are the specs:
440/500 with 10:1 compression
Comp Cams solid roller: 254/260 @ 0.050, 0.582/0.588 lift. Installed straight up. XR292 grind number, if that helps.
Heavily ported 906 heads with Stage VI -type rework (pinch area externally welded for material to straighten out the ports, intake rockers offset). The bowls have been opened way up, guides shortened, short-turn smoothed, etc. The previous owner of the heads said they had been flowed and should support 550 HP.
Edelbrock Torker II single-plane intake with 1-inch spacer.
Mighty Demon 850. I don't have the AFR readout, but it was just a bit rich on the dyno.
Timing @ 35-degrees total.
Headers are Pro-Parts-type 2-inch. Chambered mufflers were in place during the dyno pulls.
727 trans., 9.5" converter, 8.75 rear.
Everything sounded and felt fine during the pulls.
Thoughts?
Last edited by 70Drop; 06/04/14 07:38 PM.
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Re: Disappointment at the dyno
[Re: 70Drop]
#1628802
06/04/14 07:49 PM
06/04/14 07:49 PM
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Joined: Jul 2005
Posts: 707
California
BigDaddy440
super stock
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super stock
Joined: Jul 2005
Posts: 707
California
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This was a chassis dyno correct? So you're laying down 410 rear wheel hp, not engine hp. You've got to figure you're losing about 20% though an 727, converter, and heavy rear-end. 410/.8 = 512hp. Did you tune the A/F on the dyno? If not, you should! You could pick up a decent amount of power, and have better throttle response if your A/F is indeed off a bit. Honestly, most people get let down on dynos. If your car is running the number you're looking for and you know your engine is tuned correctly...let it go, and keep on racing. 
1969 A12 Roadrunner
1970 Plymouth Cuda
1968 Dodge Dart
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Re: Disappointment at the dyno
[Re: 70Drop]
#1628803
06/04/14 07:57 PM
06/04/14 07:57 PM
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Joined: Apr 2013
Posts: 345
Nebraska
451Cuda
enthusiast
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enthusiast
Joined: Apr 2013
Posts: 345
Nebraska
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Quote:
Hi,
It's been a while. I'm finally getting serious with my Duster street/strip car. I had it on the dyno and was unhappy with the results (see dyno sheet attached to the next post). The car has run a best 11.26 @ 121 mph. Here are the specs:
440/500 with 10:1 compression
Comp Cams solid roller: 254/260 @ 0.050, 0.582/0.588 lift. Installed straight up. XR292 grind number, if that helps.
Heavily ported 906 heads with Stage VI -type rework (pinch area externally welded for material to straighten out the ports, intake rockers offset). The bowls have been opened way up, guides shortened, short-turn smoothed, etc. The previous owner of the heads said they had been flowed and should support 550 HP.
Edelbrock Torker II single-plane intake with 1-inch spacer.
Mighty Demon 850. I don't have the AFR readout, but it was just a bit rich on the dyno.
Timing @ 35-degrees total.
Headers are Pro-Parts-type 2-inch. Chambered mufflers were in place during the dyno pulls.
727 trans., 9.5" converter, 8.75 rear.
Everything sounded and felt fine during the pulls.
Thoughts?
IMO Torker II isn't all that great. I always liked the Holley Street Dominator, but there's probably better intakes nowadays...maybe the Indy or a Victor intake?
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Re: Disappointment at the dyno
[Re: BigDaddy440]
#1628804
06/04/14 07:59 PM
06/04/14 07:59 PM
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Joined: Nov 2010
Posts: 1,397
Carson City, Nevada
Biginchmopar
pro stock
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pro stock
Joined: Nov 2010
Posts: 1,397
Carson City, Nevada
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Engine or Wheel Dyno? Engine = not so good Wheel = pretty good That is a lot of inches for that kind of head, that's why it falls off as fast as it does. 
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Re: Disappointment at the dyno
[Re: 451Cuda]
#1628805
06/04/14 08:04 PM
06/04/14 08:04 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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Stock head bigblocks seem to work best at 38 degrees total timing. That also could be worth a horse or two.
It's easy to get fooled in this day of "800hp" engines. Not that I would suggest that many of these numbers were achieved by trickery, but.......
What does your car weigh?
R.
I estimated your car at 3800 lb at the line. That calcs out to 540 flywheel hp. Considering that you have heavily worked but still 906 heads, and a not too insane camshaft, it doesn't sound too bad. There's probably another 50hp in it by tuning.
If you want a big step up, you need better heads and a bigger camshaft, but then driveability might just go out the window.
Last edited by dogdays; 06/04/14 08:16 PM.
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Re: Disappointment at the dyno
[Re: 451Cuda]
#1628810
06/04/14 08:31 PM
06/04/14 08:31 PM
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Joined: Jan 2005
Posts: 223
California
70Drop
OP
enthusiast
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OP
enthusiast
Joined: Jan 2005
Posts: 223
California
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Quote:
IMO Torker II isn't all that great. I always liked the Holley Street Dominator, but there's probably better intakes nowadays...maybe the Indy or a Victor intake?
I've been told before that the Torker II is less than state-of-the-art. I'm getting tempted by an B1 I see on the board . . .
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Re: Disappointment at the dyno
[Re: johnmilner]
#1628811
06/04/14 08:36 PM
06/04/14 08:36 PM
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Joined: Jan 2005
Posts: 223
California
70Drop
OP
enthusiast
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OP
enthusiast
Joined: Jan 2005
Posts: 223
California
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Quote:
baby cam.
This I've heard as well. I'd like it to be a streetable car, so I went small (at the recommendation of the Comp Cams tech). Now I'm thinking it's too small. The engine idles pretty smoothly at 800 rpm and has a ton of torque. I can probably go bigger on the cam and still be able to drive to the track.
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Re: Disappointment at the dyno
[Re: 70Drop]
#1628812
06/04/14 08:37 PM
06/04/14 08:37 PM
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Joined: Feb 2006
Posts: 1,051
The Great White North
RAMM
super stock
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super stock
Joined: Feb 2006
Posts: 1,051
The Great White North
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Running your number is possible; however, that output is not stellar considering the inches and extensive (although unknown) headwork. I doubt sparkplug gap would be a culprit of any significance. Make sure your advance curve was correct (all in by at least 3000 rpm) and somewhere between 32-38 degrees total. I've never seen a Demon that wasn't way too lean already OOTB. Also--While the cam specs look good--I've never seen one of those work all that well. Sorry--probably more questions than answers. J.Rob
2009 PHR\EMC Competitor
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2016 HotRod/EMC 3rd place SPEC Bigblock
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Re: Disappointment at the dyno
[Re: 70Drop]
#1628813
06/04/14 08:51 PM
06/04/14 08:51 PM
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Joined: Jan 2003
Posts: 31,046
Oregon
AndyF
I Win
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I Win
Joined: Jan 2003
Posts: 31,046
Oregon
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Take a look at the article in the tech archives on my old 470 engine. That engine made 470 hp at the rear wheels with a MP .528 cam and HP manifolds. The big difference between our setups is the fact that I had a manual trans and you have a 727. The automatics suck up a lot of power on the chassis dyno. Could be a bunch of little things, hard to say without spending some time swapping parts. I do know that it is hard to get cast iron heads to work right, but it isn't impossible. Some guys can really make them work. The Torker II intake isn't all that great but I doubt it is costing you a ton of power. Carb and ignition could be off or there could be a different issue. http://www.moparts.org/Tech/Archive/bb/550hp.html
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Re: Disappointment at the dyno
[Re: 70Drop]
#1628817
06/04/14 09:49 PM
06/04/14 09:49 PM
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Joined: Feb 2005
Posts: 4,316
Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,316
Prospect, PA
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Like someone said, there could be a bunch of power left on the table that you just need to find. Exhaust, intake, A/F ratio, timing, cooling, cam timing, lash,....
How is the fuel pressure....is peak power really at 5200 rpm?
And your heads are a big unknown.
Finally, what is the cranking cylinder pressure?, and who's converter are you using?
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Re: Disappointment at the dyno
[Re: BSB67]
#1628818
06/04/14 09:58 PM
06/04/14 09:58 PM
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Joined: Jan 2005
Posts: 223
California
70Drop
OP
enthusiast
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OP
enthusiast
Joined: Jan 2005
Posts: 223
California
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Quote:
Like someone said, there could be a bunch of power left on the table that you just need to find. Exhaust, intake, A/F ratio, timing, cooling, cam timing, lash,....
How is the fuel pressure....is peak power really at 5200 rpm?
And your heads are a big unknown.
Finally, what is the cranking cylinder pressure?, and who's converter are you using?
The fuel pressure is 7.5 and there hasn't been any problem with fuel delivery. Holley Blue pump.
Cranking cylinder pressure is very high - like 160 psi.
And yes, peak HP comes in at like 5200, which makes me think I'm running out of air.
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Re: Disappointment at the dyno
[Re: 70Drop]
#1628819
06/04/14 10:06 PM
06/04/14 10:06 PM
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Joined: Jan 2003
Posts: 12,144
Benton, IL.
DaveRS23
Special needs idiot
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Special needs idiot
Joined: Jan 2003
Posts: 12,144
Benton, IL.
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The heads are the biggest question mark. The low peak is the biggest indicator to me. After that, the combo could probably use more carb.
I have a similar sized cam in my 500" but mine makes about 60 more ponies and peaks at 5,600. The biggest differences in mine are; another point in comp 10.9, MCH ported Eddies, -3 Indy intake, and 1050 Dominator.
This is in a 3,450lb street car with 727 and 3.91s.
Master, again and still
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