Annular Vs. Dogleg Carb Showdown
02-22-2007, 09:52 AM
#1
Team Owner
Thread Starter
Annular Vs. Dogleg Carb Showdown
This is a perfect example of how deceptive articles can be in major car rags. just read in the "Test # 2 box. They increased the the throttle bore size So to achive the better performance. you would have to throw away your 750 and buy the 825 cfm with annular boosters to duplicate these results.
I was already to send my 750 speed Demon in and for $100 get the super annular carb job. What I would have got back was a strangled CFM 750 that would work on a lower CI, lower rpm motors.
Locally I had a carb shop install annular boosters on my 750 Speed Demon. Then we ran back to back testing on a 540 hp 406 dyno test mule motor.
The motor was equiped with 8 primary tube oxygen sensors. The highest consistant HP readings were achived with "Down leg boosters" With the single plane manifold used, staggered jetting and moddified secondary air bleeds achived the highest average numbers.
Don't be fooled by tests paid for like these recent posts of a guy wanting the brand "C" cam because he has read such great things about it. Anybody can rig test results!
http://www.carcraft.com/techarticles...wn/index1.html
I was already to send my 750 speed Demon in and for $100 get the super annular carb job. What I would have got back was a strangled CFM 750 that would work on a lower CI, lower rpm motors.
Locally I had a carb shop install annular boosters on my 750 Speed Demon. Then we ran back to back testing on a 540 hp 406 dyno test mule motor.
The motor was equiped with 8 primary tube oxygen sensors. The highest consistant HP readings were achived with "Down leg boosters" With the single plane manifold used, staggered jetting and moddified secondary air bleeds achived the highest average numbers.
Don't be fooled by tests paid for like these recent posts of a guy wanting the brand "C" cam because he has read such great things about it. Anybody can rig test results!
http://www.carcraft.com/techarticles...wn/index1.html
02-22-2007, 04:48 PM
#2
how did they compaire all the way trough the rev range for torque
and HP , all the articles I've read compairing the two show the down
leg making more hp in the upper rpm range.
and HP , all the articles I've read compairing the two show the down
leg making more hp in the upper rpm range.
Last edited by Little Mouse; 02-22-2007 at 07:54 PM.
02-22-2007, 07:50 PM
#3
Race Director
Best mod I have ever done on a carb was swapping in the annular boosters in my 825 Race Demon 
02-23-2007, 12:09 AM
#4
Team Owner
Thread Starter
From what i saw in the testing with the annulars installed is that if you had a motor that has lower rpm A/F ratio problems because of reversion and low vacuum it would cure the problems.
Motor head if yours improved it would indicate that your over carbed at lower rpm and the additional restriction of annular discharge helped with the fuel vaporization. In my case the 750 flowed enough less on the test motor that it didn't see the gains.
Motor head if yours improved it would indicate that your over carbed at lower rpm and the additional restriction of annular discharge helped with the fuel vaporization. In my case the 750 flowed enough less on the test motor that it didn't see the gains.
02-23-2007, 12:30 AM
#5
Drifting
Time for the Pros!
I had the Carb Shop do a q jet for me years ago. It worked like FI.
1 pump before starting.
My 650 vs Demon has been difficult at best. Losing some cfm for better off idle/low end would is fine w/me. If annualars can help, I'm in.
The carb flows more than my engine can use. I trust them to do it right.
I will be reporting back to forum right after dyno test.
It wouldn't superise me if there are multi problems w/carb.
Rick
1 pump before starting.
My 650 vs Demon has been difficult at best. Losing some cfm for better off idle/low end would is fine w/me. If annualars can help, I'm in.
The carb flows more than my engine can use. I trust them to do it right.
I will be reporting back to forum right after dyno test.
It wouldn't superise me if there are multi problems w/carb.
Rick
