B-pipe style manifolds

[waxhead]

If some one was to make a exhaust manifold like a Yamaha b-pipe style. What size would you want the out let to be. I know every one enlarges it but if it was a replacement you can have it to big as it will not work with stock systems

 

[Sasquachcrap]

I think 50mm is the go to number.

 

[Quinc]

I would say 48. I believe @Jr. or @MTRHEAD did some testing on different sizes?

Edit: it was tnt that posted it. See post #10
http://www.x-h2o.com/index.php?threads/who-does-boring-of-fp-mani-headpipe.188194/#post-1970940

 

[Jr.]

I would say 48. I believe @Jr. or @MTRHEAD did some testing on different sizes?

Played around with it a bunch, overall, I found, under 850cc 48.5 mm Over 850cc 50mm
So thats how I basicly do it. My 2 cents, if you do move ahead with this, invest in a good casting, and use a better grade of alum alloy. The guys that were making the C4 chambers, 5 or so years ago, also made headpipes and manifolds. I was asked to port one for a client. It was full of voids, and the alloy was very brittle. Was not a fun job!
Produce a quality product, and I’m sure it will sell well! I know I would stock several!

Ski ya, Paul

 

[waxhead]

Thank you Paul
I will look make sure we are using a high grade alloy to avoid the issue, I dont want people coming back to me unless its with a smile

 

[Jr.]

Thank you Paul
I will look make sure we are using a high grade alloy to avoid the issue, I dont want people coming back to me unless its with a smile

Happy to offer in-site, feel free to reach out anytime

 

[powerhouseperformance]

I'm with Paul. Low end goes away if it's over 48mm on a smaller engine. You can always go bigger but it's hard to put it back.

 

[Storbeck]

The things that come to mind for me would be:

Make those center bolts a little easier to get in there (maybe not possible)

Don't have the spot where the wall between the port and the water jacket is really thin

Maybe make the port 62t shaped? I'm a little torn on this because it's not that hard to "port" the opening a little bit to make a 61x manifold work on a 62t, but you can't go the other way, but having a little but of a step probably wouldn't hurt on a 61x. Anyway something to consider.

The harder question... Is there anything that can be done to these things for better overall performance? So much emphasis is put on that top opening but what about the rest of the port? Are there any choke points (wasn't the fpp casting originally designed with a 42mm hole there, so would the rest of the manifold benefit from opening up a little?

I have no answers but those are the questions I would be pondering.

 

[egbrig]

I'm with Paul. Is that a
t-shirt?

 

[MTRHEAD]

The things that come to mind for me would be:

Make those center bolts a little easier to get in there (maybe not possible)

Don't have the spot where the wall between the port and the water jacket is really thin

Maybe make the port 62t shaped? I'm a little torn on this because it's not that hard to "port" the opening a little bit to make a 61x manifold work on a 62t, but you can't go the other way, but having a little but of a step probably wouldn't hurt on a 61x. Anyway something to consider.

The harder question... Is there anything that can be done to these things for better overall performance? So much emphasis is put on that top opening but what about the rest of the port? Are there any choke points (wasn't the fpp casting originally designed with a 42mm hole there, so would the rest of the manifold benefit from opening up a little?

I have no answers but those are the questions I would be pondering.

it’s called the power factor pipe. That lay down pipe has the same tune spec as the FPP Type 9 dry race pipe. If FPP or someone else was to redo the B pipe to a bigger spec you would lose the feel it has today.

this dyno chart was made on a competitors motor back in 02’. 2002 IJSBA limited ski rules build. (no porting)
61x cylinder@82mm, 62t cases, either 48 full specs or novis, can’t remember exactly what he had at that time, MSD enhancer, Billet head with domes. You can clearly see why the average person prefers the B pipe type power
(torque) and why other newer dry pipes kill it with HP.

 

[Quinc]

it’s called the power factor pipe. That lay down pipe has the same tune spec as the FPP Type 9 dry race pipe. If FPP or someone else was to redo the B pipe to a bigger spec you would lose the feel it has today.

this dyno chart was made on a competitors motor back in 02’. 2002 IJSBA limited ski rules build. (no porting)
61x cylinder@82mm, 62t cases, either 48 full specs or novis, can’t remember exactly what he had at that time, MSD enhancer, Billet head with domes. You can clearly see why the average person prefers the B pipe type power
(torque) and why other newer dry pipes kill it with HP.

Would adding a sprayer to the head pipe on the type 9 make more torque then the bpipe?

 

[MTRHEAD]

Would adding a sprayer to the head pipe on the type 9 make more torque then the bpipe?

Short answer not necessarily: Maybe close but not equal
water pressure in the system is very low down at the initial response point when brapping throttle
not all pipes/setups respond same to water injection. Some don’t at all on the water (look at triple pipe skis)
the increased torque is normally higher than water on. Let’s say 4000+
so a type 9 with water on same motor as b pipe will still feel lazier off bottom to average person

 

[Pro-pulsion]

If some one was to make a exhaust manifold like a Yamaha b-pipe style. What size would you want the out let to be. I know every one enlarges it but if it was a replacement you can have it to big as it will not work with stock systems

I would also add to use course pitch threads vs. fine wherever possible in aluminum. I have seen far too often fine pitch metric threads strip out where course keeps going. When thinking about the grade of alloy, for an alloy to be crumbly it would suggest to me from what little experience I have currently working in the aluminum casting industry, high zinc alloys such as 7000 series are very strong but not very good for machining or corrosion prevention. If it is cast too cold it will crumble, if it is cast too hot the zinc will migrate out of the alloy and hang around the surface. You will know if an alloy has high zinc content because the surface will go dark brown when it cools. You can consider the many variations of 6061, if a custom alloy is the goal you can request higher levels of silicon for added strength but it will need carbide tooling to cut it. Personally, I say look into alloys that contain cerium for ultra high strength and heat resistance, and good corrosion prevention. Right now it is being tested for use in piston alloys. From our experience at work, it is currently only castable in open cooling forms such as clamshell and sand casting forms. DO NOT cool it with water or it will explode from shock stress...we learned that the hard way lol...oh and cerium based alloys are extremely tough to cut, break or bend.

 

[Quinc]

Or go billet like the old Able bpipe manifolds.

 

[Vumad]

Clearly the best solution is an insert like the ADA heads.

 

[waterfreak]

hopefully you can make a headpipe as well. Then we wouldn't have to rely of FP.
The billet manifold looks great but seems a bit on the heavy side