TQ.......................HP.........
347 @ 4200 ... 361 @ 6100 ... Holley 4777 650 Carb Shop
338 @ 4400 ... 363 @ 6100 ... Speed Demon 650
336 @ 4000 ... 360 @ 6100 ... Holley 750 3310 JET Perf.

TQ .................HP same +/-1
343 @ 5000 ... 349 @ 6000 ... Q-J JET Perf. ADAPTER used.
328 @ 4800 ... 351 @ 6100 ... Holley 600
329 @ 3900 ... 351 @ 6100 ... Edelbrock 600 1405
327 @ 4000 ... 350 @ 6100 ... Edelbrock 750 1407

324 @ 3900 ... 344 @ 6000 ... Holley 4180

Thought some might like this.

If anyone has questions, everyone feel free to jump in & answer.

 

This is really great info :eek:

 

That substantiates what a friend of mine said when he compared the Holley to his new Demon - about 5 - 7 hp gain, not the 20 - 25 that others have experienced.

 

Quote:
"That substantiates what a friend of mine said when he compared the Holley to his new Demon - about 5 - 7 hp gain, not the 20 - 25 that others have experienced."

Greg that pretty much sums it up on the HP thing but schools not out on how the cfm rating is reached as far as how the Demon is measured vs Holley and I especially in the last two years believe nothing a magazine article publishes.More like proffesional wrestling.Bought and paid for.And the typos are bad also,never know what they used as far as parts go when a motor build up tells of a flat tappet hydraulic cam was used and turns around and shows solid roller spring specs.Also the likes of the flow rates of Vortec heads that were supposedly stock out of the box.Rates I had to port the--- out of to achieveThey built a motor with drivability in mind then stuck a 2 inch spacer on top of a 180 degree manifold and allow how tractable the motor is..An insult of intelligience to say the least.Makes me wanta
:U
I like Competion Cams stuff.Don't get me wrong but have you in the past ever seen a test using a Reed,Shneider,Ultradyne or Crower Cam?

The tests above tell me that 650cfm was all the motor needed.The 750's used held there own because they were vacumm secondary and possibly tuned for that motor as in secondaries not fully opened.Who knows.
I want to see how the flow in cfm of a Demon is arrived at.Have never heard.Something is up when a carb needs 4 jet sizes difference to run compared to a Holley.The jets don't flow the same volume or something.



[Modified by mountainmotor, 5:55 AM 2/7/2002]

 

Ganey,
Any idea why the holley 4777 650 and the demon 650 make more hp than the 3310 750 holley? I would have thought that the bigger carb would have make more hp on top. I know that the 3310 has vacuum secondaries but they should be wide open at 6100 rpm and flowing a lot more air than the 2 smaller carbs. Very interesting information. I just switched my 3310 for a 4777 a month ago. I have not had a chance to test it out hard yet.
Ed

 

Did they spend time adjusting the jetting in each carb for maximum HP and TQ? Sounds like a ton of work to do a fair comparison. Is it in a current mag?

-Joe

 

Ed

Yes. When the carb is properly sized, going bigger does not help.

:cool:

 

Joe

Yes. The Q-J was at a disadvantage since an adapter was used. No.

:cool:

 

WOW.....thanks for the information....Very interesting..I figured the Hype on Demons was just that.....Clearly it does not justify the cost difference

 

I'm with mountian motor of the Demon carbs. My buddy here on the forum runs lean with 6 jet sizes bigger than my 750 double pumper holley. At first I thought maybe the Demon boosters do not draw as much fuel because of less air flow. I have determined that they just flat out flow more CFM.

 

The trouble with most carb test/comparisions is they tell you max hp & tq at max rpm. What I would like them to include is how a particular carb responds to tuning and how it reacts to climatic changes etc. In other words how it acts at light and part throttle, where it spends most of it's time.
I really don't care about 7-10 more hp @ 8000 rpm on a street motor. :cheers:

 

the 650s would make more power than the 750 because the engine would be sucking the air in at a higher velocity.

Chris :cheers:

 

Yellow72,
Your post in part touches on what I was getting at earlier.They stick a open spacer on top of a dual plane manifold and tell that the combination would be great for street drivability.It would be a bunch of junk would be more like it.
I have seen many motors performance killed especially with qjet and open spacer on DP manifolds.
Seen vacumm secondaries get jacked with by the reversion pulses coming off the floor of an open plenum manifold yet Edelbrock still in part recommends the use of.They know better than that! Anything to sell a part it seems!In a street car this problem usually gets"drove through" rather quickley.In a marine environment it can actually hang you there with no gain in RPM.
Good thing we don't race or drive dyno's.They are short and would wobble.

 

I'm not following your logic, but the air velocity would be greater using a 650 if a 750 is oversize for a particular motor.

 

Ganey, what was the engine/setup tested?

 

Engine on dyno. Dual plane - Edel. Performer RPM Intake.

 

Why did they need an adapter for the Q-jet? My Q-jet fits my Performer RPM just fine without an adapter.


[Modified by sharklover, 9:37 AM 2/11/2002]

 

thanks for posting that Ganey,

To me it looks like the qjet would be a real good choice to run since it was only down 2hp yet had approx. 15 more ft-lbs of torque.


[Modified by MikeC, 9:47 AM 2/11/2002]

 

Avery

The squarebore RPM was used.

Evidently you have the Q-J RPM.

:cool:

 

Ganey this is almost as good a thread as your exhaust thread of yore....

For reference: http://www.corvettefaq.com/c3/ganeyexhaust.htm