Max HP for a Q Jet
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There are folks running in the 9's in the 1/4 mile in full bodied cars in class racing. Making a lot more than 550 HP.
Would they go even faster with a *real* carb? Sure....but the Q-Jet does a pretty amazing job when set up right.
JIM
Would they go even faster with a *real* carb? Sure....but the Q-Jet does a pretty amazing job when set up right.
JIM
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From: Rockledge FL
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Agreed. The Qjet is a very good carb IF you can get it to run right. The potential is there BUT as stated many times by more than a few folks, its design is over complicated for what it needs to do, it is difficult to custom tune for different applications, is difficult to rebuild due to its design (see my first statment), and its performance will quickly degrade with time and miles. There is a reason that there are sooo many aftermarket carbs offered as Qjet replacements-there are sooo many problems from owners with Qjets!
Racer
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From: Easton PA
wow a loaded question. it will handle whatever you throw at it. no several engines runnin over 600 hp no prob with them. mine rated at 500 hp. no problems, perfect actually.BUT you need someone who knows what they are doing or disasters will happen
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They can be built to handle all power levels. There are a few tricks to make them better and the rods and jets can be changed. As 427hotrod said they can be run into the 9s. There are quite a few super stock cars that run q-jets due to class limitations. The problem is you have to pay for one to be setup right and the setup is a skill most people these days except for a few still have.
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
I suppose in Super Stock classes where they have to run "original" engine parts you have some guys in the 9's but generally you will see Holleys and Demons on the motors no matter what class at the race track and more fuel injection now too.
It is very true regarding tuning these carbs, the guys that know how to really tune any carb are getting scarce, like really scarce.
Any bubba knows hows how to change jetting and few other things but those that actually know how to setup a carb completely and actually know how it works are almost non existent these days
It is very true regarding tuning these carbs, the guys that know how to really tune any carb are getting scarce, like really scarce.
Any bubba knows hows how to change jetting and few other things but those that actually know how to setup a carb completely and actually know how it works are almost non existent these days
Drifting
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From: Somers CT
They can be built to handle all power levels. There are a few tricks to make them better and the rods and jets can be changed. As 427hotrod said they can be run into the 9s. There are quite a few super stock cars that run q-jets due to class limitations. The problem is you have to pay for one to be setup right and the setup is a skill most people these days except for a few still have.
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
I have found books on tuning a Holley / Demon carb and what they usually boil down to is the just the easy stuff and use lines like" Changing HS air bleeds is best kept for an experienced carb technician"
So they explain how to fix and tune one to a certain point and beyond that they say not to mess with it. I never bought any of the books because I leafed through them and I can see they aren't going in much deeper than the basics.
I can't comment of the Quadrajet book above, it could be quite helpful
So they explain how to fix and tune one to a certain point and beyond that they say not to mess with it. I never bought any of the books because I leafed through them and I can see they aren't going in much deeper than the basics.
I can't comment of the Quadrajet book above, it could be quite helpful
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- Image. Holley had that performance image.
- Racers. Racers used Holleys and wanted Holleys.
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the q jet has gotten a somewhat deserved bad rap. that said a properly set up Holley will out perform any other. mixture distribution kills a q jet on a drag car. but as has been said it is a good street Carb IF set up properly. GM used it on low level performance cars because it was CHEAP!
Racer
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From: Easton PA
Race Director
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From: FL
the q jet has gotten a somewhat deserved bad rap. that said a properly set up Holley will out perform any other. mixture distribution kills a q jet on a drag car. but as has been said it is a good street Carb IF set up properly. GM used it on low level performance cars because it was CHEAP!
A Holley works good at two throttle settings, idle and WOT. The Q-Jet is a much more sophisticated carb that satisfied power and emissions requirements and was much more expensive to manufacture.
GM tested and designed hundreds of Q-Jet rod and jet combos for different vehicles. The main circuit has an adjustable power piston that varies mixture based on load. The secondaries are mechanically operated with an adjustable air door that sense load and delivers just what the engine needs.
Holleys are simple and cheap. Q-Jets were expensive and sophisticated.
Le Mans Master
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A Holley works good at two throttle settings, idle and WOT. The Q-Jet is a much more sophisticated carb that satisfied power and emissions requirements and was much more expensive to manufacture.
GM tested and designed hundreds of Q-Jet rod and jet combos for different vehicles. The main circuit has an adjustable power piston that varies mixture based on load. The secondaries are mechanically operated with an adjustable air door that sense load and delivers just what the engine needs.
Holleys are simple and cheap. Q-Jets were expensive and sophisticated.