• Welcome to the new SAOCA website. Already a member? Simply click Log In/Sign Up up and to the right and use your same username and password from the old site. If you've forgotten your password, please send an email to membership@sunbeamalpine.org for assistance.

    If you're new here, click Log In/Sign Up and enter your information. We'll approve your account as quickly as possible, typically in about 24 hours. If it takes longer, you were probably caught in our spam/scam filter.

    Enjoy.

Weber 40 DCOE mods for more flow

Five Reviver

Silver Level Sponsor

Sorry DW I haven’t been able to but for consolation here’s the latest 40/45 DCOE comparison video from Penguin Motors
 

spmdr

Donation Time
So, the above video confirms, when using 40s, 32 to 33 mm chokes are about as good/big as you can

effectively use.

This tells me the Z World chart above has some validity and my efforts (moding 40s) are on the right trail.

In this test, optimized 40s made 144 HP and 140 ftLBs

Optimised 45s made 160 HP (+16) 152 lbs (+12) (with no loss vs 40s, above 2500 rpm).

So, Five Reviver, In light of the above, I think you should put in for a Name change.

More like Five REVer...?

BTW, Reviver/'REVer, did you match (increase) the intake size to the New 45s?

DW
 

Thor 1211

Silver Level Sponsor
So, the above video confirms, when using 40s, 32 to 33 mm chokes are about as good/big as you can

effectively use.

This tells me the Z World chart above has some validity and my efforts (moding 40s) are on the right trail.

In this test, optimized 40s made 144 HP and 140 ftLBs

Optimised 45s made 160 HP (+16) 152 lbs (+12) (with no loss vs 40s, above 2500 rpm).

So, Five Reviver, In light of the above, I think you should put in for a Name change.

More like Five REVer...?

BTW, Reviver/'REVer, did you match (increase) the intake size to the New 45s?

DW
Doesn't all this depend on whether or not the tightest restriction in intake tract is the venturi? So, if the manifold runners or intake port on the head are only 38mm, for example, then isn't a 45 venturi too large for that? I wonder if the Ford X head in the video has at least 45mm I/D all the way through? So many questions . . . .
 

spmdr

Donation Time
Thor, I'm not an expert on areo or even Physics, but my guess

is the intake path is a variety of restrictions.

Improving/reducing Any of the restrictions improves overall flow.

And under the heading of flow is the component of velocity.

Carbs function with velocity changes.

In the performance world, the trick is to get the least velocity

change in the carb and still have the carb function.

In the Alpine case, the stock (S5) intake valve is about 39mm.

There is a general relationship with intake valve/port size and

max usable Carb venturi size.

The point with this thread is that the typical 40 DCOE with STD

30mm chokes is too small/a significant restriction for good High

RPM Alpine engine performance.

BUT, going to the required bigger choke size (36+mm) is beyond the functional

range of the 40 DCOE.

....And how much can the 40 DCOE flow be improved?

So Thor, 45mm chokes wouldn't be much of a restriction.

45mm Webers come standard with 36mm chokes.

DW
 
Top