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thermoquad VS. Holley 750 DP #1031704
07/13/11 11:12 AM 07/13/11 11:12 AM
Joined: Sep 2003
Posts: 1,465
Carson City, NV
B
babarracuda Offline OP
pro stock
babarracuda  Offline OP
pro stock
B

Joined: Sep 2003
Posts: 1,465
Carson City, NV
On the street, does anyone have experience changing to a thermoquad. I want better mileage and throttle response especially on the road. I am aware of the weight of my right foot, so don't tell me to not open the secondaries. Did you like the way a TQ drives? I am planning on having it tuned by an expert because I am aware of the famous secondary bog.
Re: thermoquad VS. Holley 750 DP [Re: babarracuda] #1031705
07/13/11 11:38 AM 07/13/11 11:38 AM
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck Offline
Not enough dumb comments...yet
Mr.Yuck  Offline
Not enough dumb comments...yet

Joined: Jan 2003
Posts: 24,562
Brookeville, Md
I doubt you will see much differnce in MPG w/ a TQ. Unless your DP is way out of tune. Plus factor in you'll have to pay somebody to set it up then you have to figure how many miles you have to drive to make up any savings. Kind of like the fools that got rid of their paid for 20-22mpg cars to by a hybrid that gets 40's. How far would one need to drive to start saving money?

[IMG]http://i66.tinypic.com/pui5j.jpg[/IMG]
Coming soon!!!!
Re: thermoquad VS. Holley 750 DP [Re: babarracuda] #1031706
07/13/11 12:57 PM 07/13/11 12:57 PM
Joined: Jan 2003
Posts: 3,719
Space Station #5
471Magnum Offline
master
471Magnum  Offline
master

Joined: Jan 2003
Posts: 3,719
Space Station #5
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
Re: thermoquad VS. Holley 750 DP [Re: 471Magnum] #1031707
07/13/11 01:13 PM 07/13/11 01:13 PM
Joined: Jan 2003
Posts: 20,733
A collage of whims
topside Offline
Too Many Posts
topside  Offline
Too Many Posts

Joined: Jan 2003
Posts: 20,733
A collage of whims
For the street I'd go with the T-quad; really crisp throttle response, strong vac signal, and I was happy with the MPG. Demonsizzler here on the board did mine.
Re: thermoquad VS. Holley 750 DP [Re: 471Magnum] #1031708
07/13/11 01:16 PM 07/13/11 01:16 PM
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck Offline
Not enough dumb comments...yet
Mr.Yuck  Offline
Not enough dumb comments...yet

Joined: Jan 2003
Posts: 24,562
Brookeville, Md
"TQ is going to give you way better mileage around town."

how's that? the engine is going to pull the needed fuel amount reguardless of carb. Now I can see it you are running way to fat primarys...then yeah. I ran a 750DP on a very mild 340. Not sure about "city" driving but it got 17 or so on the hwy at 70 w/ 3.55 gears. I also ran a Proformed main body 750DP on a supercharged 440 managed 12-13mpg hwy running 70 w/ 3.91's. Both cars were automatics. I doubt the TQ would have been "way" better
Re: thermoquad VS. Holley 750 DP [Re: Mr.Yuck] #1031709
07/13/11 01:36 PM 07/13/11 01:36 PM
Joined: Nov 2004
Posts: 2,825
Sk. Canada
RemCharger Offline
master
RemCharger  Offline
master

Joined: Nov 2004
Posts: 2,825
Sk. Canada
A well setup t quad will get better mileage. People went away from them due to reasons stated... hard to work on, plastic main bodies, etc. the theory is sound, 90% driving on the worlds smallest 2 bbl, with the flood gates behind it. The BOG is not hard to tune out, just tighten up the rear flapper spring.

All that being said, I'd much rather have the holley.

Re: thermoquad VS. Holley 750 DP [Re: Mr.Yuck] #1031710
07/13/11 01:43 PM 07/13/11 01:43 PM
Joined: Jan 2003
Posts: 20,733
A collage of whims
topside Offline
Too Many Posts
topside  Offline
Too Many Posts

Joined: Jan 2003
Posts: 20,733
A collage of whims
I think it's a combination of the smaller primaries (higher velocity) and finer calibrations (needles & seat design), plus the vacuum secondaries. Even vs. a properly jetted Holley DP, I've had better MPG in town with a T-quad or Q-jet on the same motor.
Re: thermoquad VS. Holley 750 DP [Re: topside] #1031711
07/13/11 01:54 PM 07/13/11 01:54 PM
Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
DaytonaTurbo Offline
Too Many Posts
DaytonaTurbo  Offline
Too Many Posts

Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
I have a themoquad on my 440 and it runs great. Mileage and throttle response around town are very good. Tuned well, they offer great performance and driveability, tuned poorly and they'll make you want to throw it in the garbage can. I had to invest some time into getting mine tuned correctly, but once I got the choke and the secondaries setup properly, it was the next best thing to fuel injection. I drove my car to work every day spring-fall for 7 years with it setup like this.

Re: thermoquad VS. Holley 750 DP [Re: babarracuda] #1031712
07/13/11 02:14 PM 07/13/11 02:14 PM
Joined: Nov 2007
Posts: 21,814
Kirkland, Washington
Pacnorthcuda Offline
Too Many Posts
Pacnorthcuda  Offline
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Joined: Nov 2007
Posts: 21,814
Kirkland, Washington
TQ vs DP? 2 different animals. TQ makes for a better street driver if MPG is factored in(usually) but doesn't offer near the tuneability of a Holley DP.
A Holley VS would be a better comparision.
Re: thermoquad VS. Holley 750 DP [Re: Pacnorthcuda] #1031713
07/13/11 02:27 PM 07/13/11 02:27 PM
Joined: Jan 2003
Posts: 74,948
U.S.S.A.
JohnRR Offline
I Win
JohnRR  Offline
I Win

Joined: Jan 2003
Posts: 74,948
U.S.S.A.


This is going to be good , both in stupidity and the assine my male genitalia is bigger than yours, much like the 383 vs. 440 that is still raging ...
Re: thermoquad VS. Holley 750 DP [Re: JohnRR] #1031714
07/13/11 03:26 PM 07/13/11 03:26 PM
Joined: Apr 2010
Posts: 1,216
Under My Car
Mopar_Country Offline
pro stock
Mopar_Country  Offline
pro stock

Joined: Apr 2010
Posts: 1,216
Under My Car
Thermoquad! I have one on my ride and love it.
Re: thermoquad VS. Holley 750 DP [Re: babarracuda] #1031715
07/13/11 03:36 PM 07/13/11 03:36 PM
Joined: Feb 2003
Posts: 122
Columbus, OH
Spanky Offline
member
Spanky  Offline
member

Joined: Feb 2003
Posts: 122
Columbus, OH
I had a smaller TQ on a 360 in my Warlock. Drove it around Columbus, OH for a couple of years & loved it once I got it set up. It did take quite a bit of messing around with to get it running right, but once it was setup, it stayed stayed running great. Not sure about fuel economy, but the phenolic resin bowl was nice, since I never ever had a problem with vaporlock.
Re: thermoquad VS. Holley 750 DP [Re: Spanky] #1031716
07/13/11 03:55 PM 07/13/11 03:55 PM
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
J
joedust451 Offline
super gas
joedust451  Offline
super gas
J

Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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.

75 Duster, 451 10.87 @ 123.58 NA 97 Z28 6sp., 12.01 @ 115 on a 100 shot 71 Swinger. 360 magnum. 12.58 @ 105 78 cutlass, 469 BBC. 12.70 @ 108 on street tires. http://www.youtube.com/watch?v=Z2kqNmMfheU
Re: thermoquad VS. Holley 750 DP [Re: joedust451] #1031717
07/13/11 05:56 PM 07/13/11 05:56 PM
Joined: Jan 2003
Posts: 3,719
Space Station #5
471Magnum Offline
master
471Magnum  Offline
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Joined: Jan 2003
Posts: 3,719
Space Station #5
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
Re: thermoquad VS. Holley 750 DP [Re: Pacnorthcuda] #1031718
07/13/11 08:29 PM 07/13/11 08:29 PM
Joined: Jan 2003
Posts: 4,213
Williamsport PA North Central ...
13ChargerR/T AWD Offline
master
13ChargerR/T AWD  Offline
master

Joined: Jan 2003
Posts: 4,213
Williamsport PA North Central ...
Quote:

TQ vs DP? 2 different animals. TQ makes for a better street driver if MPG is factored in(usually) but doesn't offer near the tuneability of a Holley DP.
A Holley VS would be a better comparision.



I tend to agree. Doing recently(because i like to get a new carb and intake set up myself on a mostly stock car) I think a TQ and a Holley Vac Secondary would be a closer comparison like say a TQ and a 3310 for instance.
Re: thermoquad VS. Holley 750 DP [Re: 471Magnum] #1031719
07/13/11 09:05 PM 07/13/11 09:05 PM
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
J
joedust451 Offline
super gas
joedust451  Offline
super gas
J

Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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

75 Duster, 451 10.87 @ 123.58 NA 97 Z28 6sp., 12.01 @ 115 on a 100 shot 71 Swinger. 360 magnum. 12.58 @ 105 78 cutlass, 469 BBC. 12.70 @ 108 on street tires. http://www.youtube.com/watch?v=Z2kqNmMfheU
Re: thermoquad VS. Holley 750 DP [Re: 13ChargerR/T AWD] #1031720
07/13/11 09:10 PM 07/13/11 09:10 PM
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
J
joedust451 Offline
super gas
joedust451  Offline
super gas
J

Joined: Feb 2005
Posts: 5,221
Branson, Mo.
Quote:

Quote:

TQ vs DP? 2 different animals. TQ makes for a better street driver if MPG is factored in(usually) but doesn't offer near the tuneability of a Holley DP.
A Holley VS would be a better comparision.



I tend to agree. Doing recently(because i like to get a new carb and intake set up myself on a mostly stock car) I think a TQ and a Holley Vac Secondary would be a closer comparison like say a TQ and a 3310 for instance.



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.

Last edited by joedust451; 07/13/11 09:11 PM.
75 Duster, 451 10.87 @ 123.58 NA 97 Z28 6sp., 12.01 @ 115 on a 100 shot 71 Swinger. 360 magnum. 12.58 @ 105 78 cutlass, 469 BBC. 12.70 @ 108 on street tires. http://www.youtube.com/watch?v=Z2kqNmMfheU
Re: thermoquad VS. Holley 750 DP [Re: babarracuda] #1031721
07/13/11 10:48 PM 07/13/11 10:48 PM
Joined: Jan 2003
Posts: 9,826
las vegas
70AARcuda Offline
master
70AARcuda  Offline
master

Joined: Jan 2003
Posts: 9,826
las vegas
Quote:

On the street, does anyone have experience changing to a thermoquad. I want better mileage and throttle response especially on the road. I am aware of the weight of my right foot, so don't tell me to not open the secondaries. Did you like the way a TQ drives? I am planning on having it tuned by an expert because I am aware of the famous secondary bog.



thanks for dinner...

Tony

70 AARCuda Vitamin C
71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield)
71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas)
71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)
Re: thermoquad VS. Holley 750 DP [Re: joedust451] #1031722
07/13/11 11:41 PM 07/13/11 11:41 PM
Joined: Jul 2010
Posts: 2,091
Delray beach, Florida
P
Performance Only Offline
top fuel
Performance Only  Offline
top fuel
P

Joined: Jul 2010
Posts: 2,091
Delray beach, Florida
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.

machine shop owner and engine builder
Re: thermoquad VS. Holley 750 DP [Re: Performance Only] #1031723
07/14/11 01:22 AM 07/14/11 01:22 AM
Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
DaytonaTurbo Offline
Too Many Posts
DaytonaTurbo  Offline
Too Many Posts

Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
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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