Topic: CB750 Wet Sump Conversion - Sumpthing

[voxonda]

Oh that’s interesting.  I had originally assumed the factory oil tank line ports needed to be shut off leaving oil cooler plumbing options at the oil filter only.  Great.

George

The initial setup has the ports closed.  So leaving cooler plumbing to adaptor behind filter. But I prefer the cooler in the return line and not in the (higher) pressure side. So I suggested this to BJ. But we will start testing without a cooler and go from there.

[Tintop]

Oh that’s interesting.  I had originally assumed the factory oil tank line ports needed to be shut off leaving oil cooler plumbing options at the oil filter only.  Great.

George

The initial setup has the ports closed.  So leaving cooler plumbing to adaptor behind filter. But I prefer the cooler in the return line and not in the (higher) pressure side. So I suggested this to BJ. But we will start testing without a cooler and go from there.

Would also be interesting to know if there is any oil pressure drop depending on which ports (front/side) & pressure (high/low side).

[voxonda]

Will record all my findings, Brian. And post them here. First have to open up the engine for an overhaul.

[Tintop]

Will record all my findings, Brian. And post them here. First have to open up the engine for an overhaul.

Yes, sorry to hear about that little set-back Rob.

[voxonda]

In the meantime, while waiting for parts, started with constructing a suitable exhaust system. To make life somewhat easier cut up an old four into one which I made years ago using the oem primaries. It is not exactly what I wanted but it will do.
Need to do a little cutting and welding but this it a first step.
 

[gschuld]

Rob,

Besides the extra weight of the thicker gauge tubing used in the factory head pipes, it’s hard to argue about the carefully design gentle curvaturecof the shape.  Funny how similar they are in profile to the hand bent 1st generation race pipes.

I’m guessing that you are creating a 4 into 2 into 1 style pipe along the lower right side?  It’s going to be a tight fit while keeping clear of the Sumpthing and keeping it tight enough to avoid the full lean angle grounding concerns.  The only other option it seems is to have the 2 into 1 individually on each side and join together behind the Sumpthing.  I’m guessing that would be too convoluted.  4 individual pipes CR style is the other obvious path. 

If anyone can modify factory header pipes to work, you have my vote.

Watching with interest🧐

George

[voxonda]

Only downside of the oem tubing is the rather small diameter of 35mm. But I do love the curve of them.
A preferred 4-2-1 on one side of sump would kill ground clearance so had to opt for two individual 2 into 1 and join behind sump. Rather have the #1 and #4 coupled and #2 and #3 due to firing order  but cant have them all. Maybe in a later stage.

[gschuld]

Gotcha.  I was wondering how you were going to fit it all on the right side.  It’s going to be an interesting transition with 2 singles coming back together, joining together with a Y and out one side well clear of both the rear of the Sumpthing and the rear tire without having a small radius turn on one of the pipes.  I’m digging your creativity regardless.

George

[simon#42]

Yes one and four , two and three will give the best power .

[voxonda]

Gotcha.  I was wondering how you were going to fit it all on the right side.  It’s going to be an interesting transition with 2 singles coming back together, joining together with a Y and out one side well clear of both the rear of the Sumpthing and the rear tire without having a small radius turn on one of the pipes.  I’m digging your creativity regardless.

George

There is enough room behind the sump to join without too small radius tunes. Buit still working on some idea's. We will see.

[scottly]

Rob, you may want to consider merging the head-pipes together in front of the sump, so there is only a single pipe on each side running past the sump? As far as effect on performance with shorter primaries, only the dyno will tell.

[voxonda]

Scott, it is something I also consider. But it does effect the power output. It would make the routing of a single pipe next to the sump easier.

[gschuld]

FWIW, Carpy’s Yoshimura copy pipes have gone through several suppliers and versions.  Some hang quite low under the engine.  In fact, for a visual example, the one pictured below looks to clear an oil pan lowered 2”

Might it be worth considering for a road racer simply going under the Sumpthing along the centerline assuming the ground clearance isn’t an issue.🧐

George

[bwaller]

What about a flat (4 in a row) collector directly under the pan? I don't know the results in such a case, but have seen them before. It would take your special touch to fab a cool piece.

[gschuld]

What about a flat (4 in a row) collector directly under the pan? I don't know the results in such a case, but have seen them before. It would take your special touch to fab a cool piece.

Right, like the early Murray pipe, similar to the later Monty Campbell X-pipe

George

[simon#42]

thats not a great pipe , for max power you need to find a way to pair the pipes together 1 and 4 , 2 and three the lengths of the headers is also crucial .
looking at your first design you are not only going to loose power you also have reduced ground clearance considerably .
i think the only way to make it work is to go under the sump some how

[754]

I am betting smaller primary   make more torque..

[calj737]

I am betting smaller primary   make more torque..

I went to the same school, Frank.

[simon#42]

you went to school cal ?

[voxonda]

I am betting smaller primary   make more torque..

Diameter, length of primaries make torgue up or down scale. Form and length of the collectors too.

[calj737]

you went to school cal ?

Long enough to school you, Simple.

[Tintop]

Rob given this going to be a chop and fit exhaust, why not try and incorporate Captain's (Brent H) 360 degree design.  The NASCAR boys use very flat collectors for ground clearance, maybe some packaging ideas there?

[gschuld]

Rob,

You are going for something like this right, squeezing around the sump?

George

[scottly]

I am betting smaller primary   make more torque..

Smaller primary diameter made less torque on the FT 500, AKA Ditch Pump.

[voxonda]

Rob,

You are going for something like this right, squeezing around the sump?

George

 

Thuis could be, but still thinking of other options too.