Re: thermoquad VS. Holley 750 DP
[Re: babarracuda]
#1031706
07/13/11 12:57 PM
07/13/11 12:57 PM
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Joined: Jan 2003
Posts: 3,719 Space Station #5
471Magnum
master
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master
Joined: Jan 2003
Posts: 3,719
Space Station #5
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TQ is going to give you way better mileage around town.
Throttle response will depend on a lot of factors. A DP can mask a lot of problems by just literally dumping fuel on it.
Performance and driveability can be great with a TQ, but they are a bit of a pain to tune. Bend this, straighten that. They were designed to be somewhat tamper resistant, so you can't just turn a screw here or there. Definitely need to do your homework.
I've always considered myself to be a Holley guy, but I'm currently working through my first TQ tuning experience and learning as I go.
-Jim
I can fix it... my old man is a television repairman. He's got the ultimate set of tools... I can fix it.
Currently Mopar-less
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Re: thermoquad VS. Holley 750 DP
[Re: Spanky]
#1031716
07/13/11 03:55 PM
07/13/11 03:55 PM
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Joined: Feb 2005
Posts: 5,221 Branson, Mo.
joedust451
super gas
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super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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Smaller primaries will do better on gas then the larger, its not rocket sience, thats "only" if both carbs are tuned properly at the exact same AFR, if the 750dp is tuned lean on the primaries & the TQ is rich then yeah, the 750dp will most likely do better, Your demand is less on a smaller primary carb, the jets are smaller, less fuel, less air, better mileage, the intake also plays a role in it too, so does the cam. Its easy to figure out really, all your engine is is a vacuum pump that runs off combustion, it pulls in air/fuel & lets it out, if you restrict it, it'll consume less, a larger CI engine will demand more, thus consume more, Your engine will only pull what it needs, but on the other hand it "can" be controlled as to how much you want to give it.
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Re: thermoquad VS. Holley 750 DP
[Re: joedust451]
#1031717
07/13/11 05:56 PM
07/13/11 05:56 PM
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Joined: Jan 2003
Posts: 3,719 Space Station #5
471Magnum
master
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master
Joined: Jan 2003
Posts: 3,719
Space Station #5
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The double pumper has the ability to give a massive pump shot in all four venturies as all four open in light throttle situations, which is great for big cams and heads with low port velocity and "city" type rpms. Great for getting a car out of the hole quickly, but lousy on fuel mileage.
In a steady state cruising situations, both could be tuned for equal fuel economy. Steady state is not what you're dealing with in around town. The dinky high velocity primaries are what is what makes the thermoquad inherently better and delivering fuel economy around town.
Likewise, both are capable of being absolute turds if they aren't tuned properly.
-Jim
I can fix it... my old man is a television repairman. He's got the ultimate set of tools... I can fix it.
Currently Mopar-less
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Re: thermoquad VS. Holley 750 DP
[Re: 471Magnum]
#1031719
07/13/11 09:05 PM
07/13/11 09:05 PM
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Joined: Feb 2005
Posts: 5,221 Branson, Mo.
joedust451
super gas
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super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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Quote:
The double pumper has the ability to give a massive pump shot in all four venturies as all four open in light throttle situations,
Where did you come up with this theory , "light throttle" situations, try more like "half throttle", unless your useing one of these holleys or any with 1.1 linkage.
http://www.jegs.com/i/Holley/510/0-4224/10002/-1
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Re: thermoquad VS. Holley 750 DP
[Re: Performance Only]
#1031723
07/14/11 01:22 AM
07/14/11 01:22 AM
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Joined: Feb 2003
Posts: 21,318 Manitoba, Canada
DaytonaTurbo
Too Many Posts
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Too Many Posts
Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
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Quote:
Quote:
The TQ or QJ will still win over a squarebore carb, smaller primary bores get better mileage if the AFR is the same on both carbs. & you can make a 750dp get right at the same mileage as a 3310.
if ther A/F ratio is the same for either carb, can you please explain why one will get better mileage over the other? same amount of air, same amount of fuel.
the one thing i could never get used to on a spread bore carb is how much further you need to push the gas pedal in normal driving to get the same acceleration as a square bore carb.
The smaller venturis are supposed to be more responsive to small changes in vacuum/load during normal driving, so they should respond more precisely to fine changes in throttle position as you would encounter during daily driving. FWIW I always found spread bore carbs to be more responsive when driving around town than square bore carbs.
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