does desktop dyno help or hurt
Thread Starter
Melting Slicks
Joined: Dec 2000
Posts: 2,130
Likes: 1
From: mesa,az
does desktop dyno help or hurt
As i kick around the different combos for the 406 engine I plan to build i am playing with desktop dyno. Now i would LOVE to use a set of ramhorn exhaust on this engine but am warry of giving up that much HP. In the past a few smart folks ( SWC Duke for one) have stated that if i am running mufflers the differnce between cast iron manifolds and headers is not that much. On the other hand a few people who seem to know what they are saying, UDHarold, GoFast etc... disagree. so i like to run desktop dyno. ugh, acording to what that says, I'd rather shoot myself in the head then run iron manifolds. Still, I am not so sure it is right. Just dosent seem right that i would lose 20% of my HP going from small tube headers with mufflers to HP manifolds. Has anyone had any similier experiance with these computor programs. I know they are considered the hot setup but I am not so sure.
Thanks
greg
Thanks
greg
Drifting
Joined: Feb 2005
Posts: 1,738
Likes: 2
From: San diego ca
I think the likelyhood that Desktop Dyno is terribly accurate is probably pretty low...what you do get out of it though is an indication of the effect of a particular change.
when i did my motor build up I first started by doing a bone stock L82 build up in Desktop dyno - surprisingly it was within 8 hp of the factory net ratings...however that program doesnt take into account things like Catalytic converters...emissions gear etc....
From that baseline I then started making changes to the cams/heads/ etc... that gave me a good idea of what sort of changes to the powerband I could expect...what would work, what wouldnt...but I dont think you can take the final numbers as an accurate representation of the final numbers...there are simply too many variables that the program doesnt take into account.
does it hurt to use it....no I dont think so...but dont go bragging you got dyno numbers on your new motor either
when i did my motor build up I first started by doing a bone stock L82 build up in Desktop dyno - surprisingly it was within 8 hp of the factory net ratings...however that program doesnt take into account things like Catalytic converters...emissions gear etc....
From that baseline I then started making changes to the cams/heads/ etc... that gave me a good idea of what sort of changes to the powerband I could expect...what would work, what wouldnt...but I dont think you can take the final numbers as an accurate representation of the final numbers...there are simply too many variables that the program doesnt take into account.
does it hurt to use it....no I dont think so...but dont go bragging you got dyno numbers on your new motor either
Senior Member since 1492
Joined: Aug 2000
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From: Just because I'm paranoid doesn't mean people aren't out to get me...
St. Jude Donor '09
I found it a little amusing. I think it calculated my combo to peak at 650HP @7,000 or something. 
I think it does give you an idea of the amount of HP difference using full length headers vs stock manifolds.Like anything else the more accurate info in, the more accurate info out. If you've got good head flow numbers and accurate cam profile (I didn't) your result will be better.
It has a disclaimer too somewhere that the roller cam calcs are way off.
Some people swear by the program. I'm sure some guys would say "Hey my engine dyno'd at 650HP @7,200!"
Not clarifying that it's just Desktop Dyno. 
Racer
Joined: Sep 2004
Posts: 424
Likes: 2
When you input cast iron exhaust manifolds does it know that you have Ram-Horns, extrude-honed, ceramic-coated, actual flow #s. I beleive in this area you could have a huge margin for error. That being said, unless I was trying to hide the fact that I had made performance mods, I would "shoot my self in the head" before I decided not to use tube headers.
Le Mans Master
Joined: Nov 2004
Posts: 6,434
Likes: 0
St. Jude Donor '07
Desktop Dyno gives you very high HP numbers. When I punched in all my stuff it said I had 600 hp.
When I use engine analyzer (a 500 dollar program) It says I have around 470 with sounds correct. Except my engine analyzer demo expired so I can't use it anymore.
When I use engine analyzer (a 500 dollar program) It says I have around 470 with sounds correct. Except my engine analyzer demo expired so I can't use it anymore.
Drifting
Joined: Oct 2003
Posts: 1,486
Likes: 10
From: Big Pine Key FL
check out the Stainless rams horns at Speedway...
http://www.speedwaymotors.com/xq/asp...tLargeView.htm
http://www.speedwaymotors.com/xq/asp...tLargeView.htm
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Melting Slicks
Joined: Jun 2002
Posts: 2,844
Likes: 99
From: Orrtanna Pa.
I would think even the best program is only a "guess" at what could happen with a particular combination of parts.
I've done the buttometer program comparing non header to header combinations I've built over the years,and the headers always produce a noticible(I say noticable,because even my butt can't feel a ten horse difference) increase in power.
The pro's of cast manifolds is the "stock look",and they are quieter.
I've done the buttometer program comparing non header to header combinations I've built over the years,and the headers always produce a noticible(I say noticable,because even my butt can't feel a ten horse difference) increase in power.
The pro's of cast manifolds is the "stock look",and they are quieter.