Triple carbs for stroker motor

[siteunseen]

2 hours ago, Patcon said:

I have always found Dave Patton to be very helpful

I've used futofab for parts simply because of the shipping prices. I live closer to the East coast so he saves me a good bit. But he has been very helpful as far as a gentleman that owns a business. 

I give him 5 stars! Would buy from him again.

[jitenshakun]

Oh, and the Cannon is perfectly good. For any intake do have it port matched to your head though. That'll help any intake out.

[Seppi72]

Thanks for the replies, folks.  Here's another related question for you then: I know it's very important to "port match" the intake manifold to the head as one would obviously want an unrestricted, predominantly laminar flow of mixture going into the head.

However, what about the other end of the manifold?  What I mean is, for instance, suppose one has 40 mm carbs and puts them on a 44 mm intake manifold?  Clearly, there will be no flow restrictions but there might be eddy currents or turbulence generated by the instantaneous change in diameter.  Might there actually be an opportunity for the fuel to condense somewhat in the manifold if there is, in fact, a pressure drop from such a mis-match?  Similar to the contrails seen off the rear wings of F1 cars in humid conditions?

[jitenshakun]

I was wondering the same thing, but is it to the choke or to the carb body?

[jonbill]

you should port match the manifold to carb body. 

[Seppi72]

In reality, I'm thinking of mounting Weber 40 DCOE carbs on a Mikuni 44 manifold.  I put a carb and spacer on the near end of each one to illustrate differences.  I roughly measure the distance from the tabletop to the highest point of an air horn as 295 mm for the Cannon and 240 mm for the Mikuni.  That gives me almost 2 inches to play with for installing an air box.  However, it also brings the carbs that much closer to the headers.  But, putting in a heat shield is not an issue for me.

 

 

 

[Seppi72]

I've looked at a Pierce manifold and it's about the same size as a Cannon.

[crayZlair]

Remember that the intake runner length will affect the torque curve.

Generally, the shorter the runner, the torque curve moves to a higher RPM.

 

[Seppi72]

I certainly did not know that.  Are there any equations for making a determination of the effect?  Or, do you just have to put different configurations on a dyno?

[crayZlair]

I think that there are too many factors involved to come up with a simple equation. The dyno tells all! 😃

[jitenshakun]

I think that there are too many factors involved to come up with a simple equation. The dyno tells all! [emoji2]

Yup, based on you application. Where you want to make power, what your cam is doing, etc.

Port match, run a reasonable velocity stack, a good air filter and call it job done.

[crayZlair]

41 minutes ago, jitenshakun said:

Port match, run a reasonable velocity stack, a good air filter and call it job done.

Air filters ? We don't need no stinking air filters ! (Autocross only) 😁

Length from head to end of velocity stack is approx. 300mm (11.75 ")

 

Edited September 28, 2021 by crayZlair
added more for clarity