General Category > Quadrajet Carb Talk and Tips

How much hp can a quadrajet support?

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Toronado:
If you want a daily driver (not race) stay Q-jet!

(BUT) I was thinking there has to be a limit.
Theres no way a Q-jet could work on a 572 BB
blown or turbo, it would run out of fuel just idling, right?

So is there a limit with the Q-jet, Im sure there is a limit.
I love the Q-jet but just watching many drag races they
are not the best drag race carb. I have heard if its all
out competition. just look at the design differences between a race
carb and a Q-jet the race carb flows better if set up
with the correct engine combination (not stock)
for smaller combo's ya the Q-jet is one of the best hands down but to a certain point.

There are larger carbs for good reason they are
definite situation were more air and fuel are required
. So I figure over 800hp or torque you will need
bigger carb. than Q-jet makes, because GPH fuel requirements.

I would bye this one for my imaginary 572 BB block build,
C & S Aerosol 1000CFM Billet Dominator Alky Carburetor (incredible design)
http://compare.ebay.com/like/150560900686?ltyp=AllFixedPriceItemTypes&var=sbar&rvr_id=218160508287&crlp=1_263602_304662&UA=WXO%3F&GUID=c983571d1250a06459b0f160ffdb8a2d&itemid=150560900686&ff4=263602_304662

Cliff Ruggles:
I love the Q-jet but just watching many drag races they
are not the best drag race carb.

Actually, they are an EXCELLENT full race carb. 

My current unit has been in service for over 15 years on 4 different engines.  455.4hp, 494hp, 514hp, and currently over 550hp.

I've made over 1200 documented track runs with this carb, never once stumbled, hesitated, bogged or gave any troubles anyplace.

It's been good enough to win the Pontiac Nationals 3 times, the APEX Musclecar/Import Challenge, and quite a few finals at local bracket races and fast street car events, etc.

The best thing about using a Q-jet for racing, is that tuning changes take seconds, and all external, carb doesn't have to come apart.  The adjustable airdoor makes for perfect lauches with any track conditions.

Once you get around the fuel delivery deal, the rest is easy.

We have carbs clear up to 897cfm, which can easily support engines over 750hp and cars running into the 9's.  As much success as we have with them, there is still some 1970's mentality still lingering.  The old "get rid of the Q-junk and get a Holley" is regurgitated once in a while, but NEVER when our car is sitting in the staging lanes in the final rounds at a big race!.......Cliff

Toronado:
What about the differences between a race carb and a street carb (rather bad or good),
the Q-jet is great and I amazed to hear that they can be customized to 890 cfm!.

 I sure do agree the Q-jet can work great as a race carb and often beats
other brands on the track, I have seen the reports. It just seems to me
that the race carb does have improvements for all out performance, like
deleted choke, larger fuel bowl, better air flow.

But a race carb does have less parts & a far
more simple design, and is not built with idle quality in mind.
A Q-jet does have a lot going on as far as parts and
different tunning points for good idle and power, and can be tweaked
in many ways way beyond a race carb so you can idle real smooth.

Also a race carbs design focus is more on getting the most air and fuel
as fast as possible to the hungry race engines that have wild cams and lopy idles
& dont use parts for low rpm operation like a standard street carb with choke towers.

The Q-jet is very powerful I have experienced its performance in my cars, on my 1972 caprice 454, my 1981 corvette 350, & my 1970 toronado 455. i just like the race carbs because of there innovation and
track results not that there the best, but they have there place. ;D

Cliff Ruggles:
One of our customers has a dedicated 9.90 race car.  He has at his disposal a 1000cfm Quick Fuel Holley, and one of our 897cfm q-jets.

He claims there is no more than .02 seconds between them at any track in any weather.

He uses and prefers the Q-jet because the car idles better, and is easier to "stage" (footbraked car).

I doubt if too many folks reading these threads have 730hp engines in their cars and run into the 9's, "race" car or "street" car.

The biggest downside to using a q-jet for racing is NOT the small float bowl. 

Doesn't matter how big the bowl is.  End hung float bowls are not as good as a center bowl with the jets in the bottom of it.

The q-jet only has ONE needle/seat assembly to feed the HP of the engine.  Fuel delivery in really high HP applications must be up to par to get them to work.

One of our Super Stock customers has an early Camaro powered by a 355 SBC.  He used two 250gph pumps and 10AN lines, with a full bypass system with his q-jet.  He runs mid 9's at over 150mph, and it's a smaller "750" cfm unit!......Cliff

Toronado:
Great read Cliff those fuel pumps that guy is using
is some serious gas flow way more than I thought
a Q-jet could handle, talk about running like fuel injection.
I figured the likability of the Q-jet is due to
great idle and massive power potential which
is the best of both. I bet the inventors are proud
to see they still have a following and hold up compared
to new designs. 8)

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