BLP Main body BX4

[Robban 54]

Has anyone tried BLP BX4 Main body retrofit kit?
https://blp.com/cart/images/BX4RK_Uncoated.jpg
Robban

[ClassAct]

Yes. I have a BX4.

[Robban 54]

Any difference from a regular Holley?

[ClassAct]

No comparison, the BLP is just better.

[BradH]

At one point on here I posted asking if anyone had back-to-back tests of comparable configuration (venturi size & booster type) 4150 carbs based on traditional "HP" main body vs BX4-type main body. At the time nobody provided anything, so I'm still waiting to hear of quantifiable improvements from the new design.

I'd certainly expect a BX4 is "better" in a number of areas, but how that translates into dyno / on-track performance still seems unclear. I may do my own testing in the future, but that would be pretty far down the road given what else is a higher priority for me. Thx

[ClassAct]

At one point on here I posted asking if anyone had back-to-back tests of comparable configuration (venturi size & booster type) 4150 carbs based on traditional "HP" main body vs BX4-type main body. At the time nobody provided anything, so I'm still waiting to hear of quantifiable improvements from the new design.

I'd certainly expect a BX4 is "better" in a number of areas, but how that translates into dyno / on-track performance still seems unclear. I may do my own testing in the future, but that would be pretty far down the road given what else is a higher priority for me. Thx

I haven’t done back to back yet. I might later this year, but it depends.

[Robban 54]

1612288959659422818160.jpg

I got my BX4 today.
Will return with assembly and test drive when the snow is gone and the temperature is above freezing.

[BradH]

What venturi size & throttle bore is yours for? Thx

[Robban 54]

1,560+1,750

[jmarkaudio]

Size for size all else equal probably little if any difference for most. Great for one you need to upsize, and you can chose the booster that can impact performance. Plus the price for billet is only a little different than the castings available.

[Robban 54]

Only the look does probably 10 horsepower.
Now it is at least assembled and test started.
Test drive will have to wait until spring.

[Bob M]

Have you had a chance to run the car with the new main body yet? Any feed back would be appreciated.

[Robban 54]

Have not been able to drive that much yet.
It's still pretty cold.
But the low speed seems to be about the same.
I have increased the main jet a few steps but it's still too lean.
There seems to be a gap between low speed and high speed.
Robban

[Mike Laws]

Have not been able to drive that much yet.
It's still pretty cold.
But the low speed seems to be about the same.
I have increased the main jet a few steps but it's still too lean.
There seems to be a gap between low speed and high speed.
Robban

Venturi/throttle bore ratio is not ideal which is causing the need for more fuel. The gap between low and high speed is understandable. Your best bet is to put an aggressive annular booster in it. (Mark has some.) Gotta get that air moving to pull fuel.

[Tuner]

Have not been able to drive that much yet.
It's still pretty cold.
But the low speed seems to be about the same.
I have increased the main jet a few steps but it's still too lean.
There seems to be a gap between low speed and high speed.
Robban

Venturi/throttle bore ratio is not ideal which is causing the need for more fuel. The gap between low and high speed is understandable. Your best bet is to put an aggressive annular booster in it. (Mark has some.) Gotta get that air moving to pull fuel.

Isn't it a simple shame so many carb people apparently haven't read NACA TR49 and similar related historical research papers that are available free for the time to learn.