[Johnny406]

I was recently talking with a gentleman about my Holley Gen III 950CFM Dominator (2 circuit) carb. It was a interesting conversation and he stated that a 4150 of the appropriate size will outperform a 4500 of the same size on a footbrake car but the advantage goes over to the 4500 if the car is on a transbrake.

I'm smart enough to know that I don't know on that one...

Is that a logical conclusion? I was thinking of having my Doninator carb converted to E-85 for the higher reving/higher compression 433 that I am building to replace the 463 that I've been running t=for the past 13 years. Would I be better off selling my Dominator and 4500 Northwind and buying a new 4150 setup? I will always be a no-box/footbrake racer.

[PAUL K]

Depends on the combination. A smaller carburetor will usually be more responsive down low and can 60ft better than a carburetor that is to big... But an engine the truly needs a 4500 and is set up properly will drag the smaller carburetor down the track nine times out of ten.

[steve25]

A bigger detail to me you need to consider in all this that you have not spoke of is your converters stated 3600 stall speed and where your new smaller stroke motor is going to make peak Tq.

You have posted nothing about your new motors cam.

[badgto]

I ran my 455 stock 067 heads backup motor this year bracket racing. I ran 3 different carbs. First one was my high dollar 1200 cfm 4500 base with times in the 7.30-7.20s @ 94. 60' was 1.53 Depending on weather. Very inconsistent. 2nd one was a 850 base ran 7.20', s @ 92 mph. limited run time on it. But noticeable down power difference in 60' Last carb was a 1050 4500 base that ran the best. 60 ' was 1.48 7.02 @ 96 mph

[Johnny406]

Originally Posted by steve25

A bigger detail to me you need to consider in all this that you have not spoke of is your converters stated 3600 stall speed and where your new smaller stroke motor is going to make peak Tq.

You have posted nothing about your new motors cam.

Good morning, I was asking in more of a general way than specific as I never heard that logic before.

As for the actual build, if I can swing the money after all the block machine work (splayed 4 bolt caps, studs, bore and hone with a torque plate etc) I plan on using a solid roller Paul K sold me. If not, I'll be using this nitrous grind Schneider SFT cam. I'm generally a 1/4 mile bracket racer but we do have a 1/8th mile no-prep series I like to do with the bottle.

Crank is my new Molnar forged 4" stroke with Molnar rods. Attached are the pistons I'm going to use and I do have a 4400 converter. I expect to need to change up to a 4:10 gear to get a little more wheel speed.

[Dragncar]

Its bracket racing, most of the time you are better off running a little smaller carb than one that would make maximum power for the sake of actually trying to win races.
Usually a good 4150 will be more consistent than a 4500 and get the typical heavy bracket car out of the hole quicker.
Every time I tried a 4500 it was harder to win bracket races.
The track and a dyno are 2 very different tings.

[Johnny406]

Originally Posted by Dragncar

Its bracket racing, most of the time you are better off running a little smaller carb than one that would make maximum power for the sake of actually trying to win races.
Usually a good 4150 will be more consistent than a 4500 and get the typical heavy bracket car out of the hole quicker.
Every time I tried a 4500 it was harder to win bracket races.
The track and a dyno are 2 very different tings.

Thank you, my ATM E-85 850 is super consistent, I won a Wally index racing last year with it. The heads up racing is just for fun, I'm always outgunned though I tend to surprise and take out a heavy hitter or two every race...

My current motor, in my opinion/observations, is too RPM limited for the 4500 Northwind. The car picked up with the port matched RPM, TKII and very ported by Greg Merrick HSD. I'm leaning on selling both the 4500 Northwind and the 950 Gen III Dominator and use the funds to buy a new 950 ATM E85 carb and use the rest of the proceeds towards building the new motor.

[chuckies76ta]

Originally Posted by Johnny406

I was recently talking with a gentleman about my Holley Gen III 950CFM Dominator (2 circuit) carb. It was a interesting conversation and he stated that a 4150 of the appropriate size will outperform a 4500 of the same size on a footbrake car but the advantage goes over to the 4500 if the car is on a transbrake.

I have both of these Northwind intakes. 4150 and 4500. Both are port matched to the E-heads by SD.. I've tried the 4150 on our engine this summer and it lost et and mph but not by much. Were running a 1050 Dominator on the engine. The difficulty is that this was done during different days, temp and track prep. The only difference that I know for sure is, we had out best 60 ft with the 4500 intake. This is on a 505 cu in engine, and using foot braking off the line. So, I'm not sure I would agree with the statement your friend made. Trans brake is a whole different thing in that it allows the rpm to increase with no load on the engine as compared to foot braking. It would be best for you to do a comparison when your ready to track run and then you can make a more informed decision. And then update us.

[PAUL K]

It takes quite a bit of engine for a 4" stroke factory block combo to want a 4500 style carburetor. I posted a video of my car running one of my favorite all around 446 engines. The 4500 never helped the combo. I tried several 4150's and the fastest was one of ours that flowed around 1000 cfm and ran 10.50's NA. The smaller one I tested this day was a custom deal the carb builder was sure would help. It slowed down noticeably over the bigger carb.... Some of this might change on a lighter car, mine is definetly on the heavy side.


https://fb.watch/o7xUa0KozN/?mibextid=9R9pXO

[Steve C.]

Back-to-back track test in 2002 with my 4.125 stroke / 450 cid N/A combo.
97-98 degrees / 50% humidity / 29.25-29.40 pressure

Victor intake w/ PRC HP950 carb = 10.755 at 125.48 mph / 1.589 60-ft
Victor intake w/ 8896HP Dominator = 10.685 at 126.61 / 1.578 60-ft

Prior to the above track testing we used a Brad Urban modified 750 carburetor on the dyno.
The custom PRC carb was purchased later and used in the run above.

On the engine dyno the engine made about 15-20 more HP with the Victor/8896HP Dominator set up over a Brad Urban carb/Victor set up.
With the Brad Urban carb it made 680 hp at 6800 rpm. We used a 1/2" open spacer on the Victor intake.



.

[Dragncar]

Originally Posted by Johnny406

Thank you, my ATM E-85 850 is super consistent, I won a Wally index racing last year with it. The heads up racing is just for fun, I'm always outgunned though I tend to surprise and take out a heavy hitter or two every race...

My current motor, in my opinion/observations, is too RPM limited for the 4500 Northwind. The car picked up with the port matched RPM, TKII and very ported by Greg Merrick HSD. I'm leaning on selling both the 4500 Northwind and the 950 Gen III Dominator and use the funds to buy a new 950 ATM E85 carb and use the rest of the proceeds towards building the new motor.

Its the beauty of bracket races. When I won my 2nd Wally I took out this guy with a big money bracket car on both Saturday and Sunday. He seemed happy when he drew me on the opening round Saturday because my car looks like junk.
Those are the best guys to take out.

You new carb, might want to give these guys a call.
http://www.performancecarb.com/

They now almost exclusively sell all billet USA made carbs. Holley have been made in CHINA for awhile now and the quality control went down far enough for them to look for something else.
Go to the site and click on Drag Race Carbs and scroll down and you will see some pics of the billet carbs. Up to 1200cfm 4150 carbs . They are honest and give free advice. Into E85 big time.
Will straight up tell you that 1200cfm 4150 does not make quite the power of a 1200cfm 4500 carb. But customers luv them. They get a really strong signal. The boosters are lower in the venturi than a cast Holley.

[BILL BOWMAN1]

Never a bracket racer, but all my motors always picked up when I switched to a dominator.

[CraigG.]

I would vote for a 4150 for a foot brake consistency from track to track and weather changes - I run and love E-85 it tends to be slightly less throttle responsive than gas. 4500 for all out power - 4150 for consistency.
Mark Sullens for carb building.

[Skip Fix]

You can get a 4150 baseplate that also fits 4500 manifolds.

[PAUL K]

You can also modify an existing 4150 baseplate to work on a 4500 manifold.

[chuckies76ta]

Originally Posted by PAUL K

You can also modify an existing 4150 baseplate to work on a 4500 manifold.

Paul: Do you know if the flange area is large enough to fit the 4500 without an adapter? I realize the dominator is a larger 4 bolt hole pattern. Thanks

[Tandyman]

I have a Holley 1000HP that I put a Quickfuel dual pattern baseplate on. It will not bolt on to any of the 4500 manifolds
that I have tried it on. It needed an adapter/spacer to get linkage/pump clearance on them all.
Kind of disappointing really .

Glenn

[PAUL K]

Originally Posted by chuckies76ta

Paul: Do you know if the flange area is large enough to fit the 4500 without an adapter? I realize the dominator is a larger 4 bolt hole pattern. Thanks

It's real close. We usually make a plate an adaptor out off a heat insulating plate.

[Tim Corcoran]

I run a 8896 1050 4500 on a victor and I foot brake. Engine is very responsive I bring it up to 1100 RPM and hammer it, no bog it just rips. I tried launching off a t-brake my 60' times were the same and I red light every time soi I don't use the brake. 473 cubes 330 cfm e-heads old style combustion chambers.