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CC Advertisers
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11-18-2003, 07:26 AM
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CC Member
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Join Date: May 2000
Location: Northern VA,
VA
Cobra Make, Engine: Classic Roadsters
Posts: 2,765
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Not Ranked
Desktop dyno help needed
I just wrote another thread asking for info on taking my valve lift from .488 to .518 relative to valve clearance via different roller rockers. But, If anyone has a desktop dyno and would run my numbers for me, I would appreciate it. I want to know just what kind of HP and TQ increase I can expect from this. Here is my engine info:
302 with 8.5:1 compression, Edelbrock aluminum heads, single plane intake, 700 CFM Holly, MSD ignition, Large tube headers, 3" open exhast. Cam info:
Now:
288 total duration
228 @50
.488 lift
Lobe displacement angle 108
Planned:
288 total duration
230 @ 50
.518 lift
Lobe displacement angle 108
So, If any of you fine people can run my before and after numbers, I would appreciate it.
thanks
Ed
__________________
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Last edited by CobraEd; 11-18-2003 at 07:33 AM..
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11-19-2003, 03:13 PM
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CC Member
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Join Date: Aug 2003
Location: CT,
Posts: 26
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Not Ranked
Hey CobraEd,
Looks like you are installing a set of 1.7 rockers to up your lift....you won't see much gain from adding a little lift, maybe 3-5 hp.....if you do this make sure to check you the tip on the valve through its movement to make sure that it stays in the center....most times on a non adjustable valvetrain you will not be in the center of the valve which will cause rapid wear of the valve guides, a cheap adjustable pushrod is available from trickflow if there is a problem to find what length you need....and make sure your springs can handle the added lift for coil bind etc....it can cause the springs to get hot/brittle and break.....stock piston notches will have plenty of clearence so you shouldn't have to worry about that.....How are you getting more duration @.050 from roller rockers?
Brian
www.teamcracing.com |
11-19-2003, 03:19 PM
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Renegade Nuns on Wheels
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Join Date: Aug 2001
Location: columbus,
Oh
Cobra Make, Engine: Unique 427 roadster with 351C-4B
Posts: 5,129
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Not Ranked
Brian, did you run desk top dyno? What kind of variables can you enter? Want to do another?
Thanks
Rick
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11-19-2003, 03:34 PM
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CC Member
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Join Date: Aug 2003
Location: CT,
Posts: 26
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Not Ranked
I have desktop dyno at home.....I'm talking from experience......
Brian
www.teamcracing.com
I will run tonight if need be........... |
11-19-2003, 07:41 PM
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Senior Club Cobra Member
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Join Date: Jul 2000
Location: Las Vegas,
NV
Cobra Make, Engine: ERA 427 SO
Posts: 1,126
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Not Ranked
Ed, Brian is right...my desktop dyno runs using your info show 295 HP @ 5000 RPM and 337 #-ft @ 4000 RPM with the 1.6, and 297 HP @ 5000 RPM and 337 #-ft @ 4000 RPM with the 1.7 rockers (using YOUR numbers for duration @ 0.050")...not really worth the effort according to the computer...
__________________
Ken
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11-19-2003, 08:12 PM
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CC Member
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Join Date: Jun 2001
Location: Washington DC Metro (Virginia),
VA
Cobra Make, Engine: Classic Roadsters, Tweaked 351W, T-5Z, CRII Tech Support Team.
Posts: 1,895
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Not Ranked
Desktop Dynois arguably one of the best, and cheapest tools any hot rodder, or Cobra builder can have on his computer. And for for the $40 or $50 they charge for this, this has got to be the Stocking Stuffer this year.
I must have played what-if for a solid year with cams, lifters, rocker arm ratios, compression ratios, valve sizes, manifold types, carb sizes, ad nausium before assembling the engine.
Surprisingly enough, on the chassis dyno at DVSF the HP and TQ curves where right where Desktop Dyno said it was going to be.
Where Desktop shows its stuff is in showing you the entire power curve, not just peak values.
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11-20-2003, 11:55 AM
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CC Member
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Join Date: Aug 2003
Location: Southeast,
CT
Cobra Make, Engine: ERA #375 427 S/C - 428FE - Toploader - 1968 AMX 390 Go Pack 4 Speed - My Daily Driver is a 2004 Crossfire
Posts: 872
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Not Ranked
Guys:
Just how many Desktop Dyno versions are there out there for sale?
There appears to be 3 versions?
Mr. Gasket Desktop Dyno (with book and Diskette)
Dyno 2000 (CD and no book)
Dyno 2003 (CD and VERY EXPENSIVE!!)
Which version are you guys running?
Thanks
__________________
Art in CT
See My Website at http://www.lithicsnet.com
A car can massage organs which no masseur can reach. It is the one remedy for the disorders of the great sympathetic nervous system. Jean Cocteau 1889-1963, French Author, Filmmaker
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11-20-2003, 12:15 PM
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Senior Club Cobra Member
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Join Date: Jul 2000
Location: Las Vegas,
NV
Cobra Make, Engine: ERA 427 SO
Posts: 1,126
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Not Ranked
Red, I've got 2000...they're probably all good for relative purposes...I use it to model changes, relative to a baseline...don't know how close the output is to the real world, but...garbage in, garbage out...
A lot of the posts indicate DD is within 10%, and maybe 5%, depending on how accurate the input data is...
__________________
Ken
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11-20-2003, 01:58 PM
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CC Member
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Join Date: Aug 2003
Location: CT,
Posts: 26
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Not Ranked
Any program will be more accurate dependant on the amount of info put in and variables that you can add....There are so many things that you can't enter, weather etc....which all play a factor, but is a fun tool, and can make you think about whether something is going to help or not, and if not why or why so little etc.....There is another program other than DD, that supposedly is very accurate, but you have to map everything, by the time you are done, you could have built the motor and tested it....can't think of the name of the software off the top of my head though....
Brian
www.teamcracing.com |
01-14-2004, 07:25 AM
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CC Member
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Join Date: Jan 2004
Cobra Make, Engine:
Posts: 1
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Not Ranked
hi ijust want to know if someone help you with your tuning tip  |
01-14-2004, 09:12 AM
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Senior Club Cobra Member
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Join Date: Jun 2001
Location: Cincinnati, Ohio (well, Milford, really),
Posts: 320
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Not Ranked
Any dyno program out there that will run on the Mac?
__________________
Doug
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