Compartmental dry sump design questions. 1

[MNRaptor]

I have been digging information on design for a dry sump pan for a DOHC V6. I have discussed dividing the mains into separate compartments based on the it's current use in Pro Stock showing improvements in power.(The source for help works for a large pan manufacturer) I am short a few design principles however and hoping someone here can help. Basically, I believe that dividing the bottom with air tight seals between each of the mains would be a complete waste without also doing something to separate the oil returns from the head in some manner. There are several thoughts I had on this: You could block the returns and use a separate stage on the pump for separate return lines from the heads. OR. You could block all but one return so that each head was associated with only one compartment below OR you could divide the head in the same manner that the mains are divided in and continue utilizing the stock oil returns. The last option however would be extremely difficult do to the cams so I doubt that is the route to take. So I am curious as to what suggestions/experience you all may have.

Also I am trying to decide the best way to handle the crankcase breathing so that there is not too much vacuum causing seals to fail etc. Any help there would also be appreciated.

FYI (if it matters), This engine will be turbocharged running a typical boost level above 35PSI.

Thanks in advance,
Mike

 

[JadedSilver]

Depending on the head design, it really wouldn't be too difficult to isolate the the valvetrain cavity volume into separate "chambers", which could then be associated with a matched "chamber" in the block. Most common OHC engines utilize split bearing races for the cams, and with some proper fabrication, you could design and fabricate a valve cover that could seal off chambers inside by sealing against the top of the races and possibly a TIG welded riser/wall in the valvetrain cavity. Again, this really depends on the head design up in the valvetrain cavity but I think it's safe to go out on a limb and say It'll work in your application.

As far as limiting the vacuum in any particular chamber goes, a simple tuned reed system in the head would work fine. Finding the perfect reed balance for your hg liit will take some trial and error, but will work. I've had great success with this setup. Simple, effective, reliable, and easy to repair/replace reeds IF one does fail. On my car I use carbon fiber reeds and have yet to replace them due to failure or wear. Some people have setup electronic solenoid packs to control the vacuum draw in the crankcase, assumed controled by separate vacuum micro switches and a suitable circuit. Benefits a more finely tunable setup, but at the drawback of complexity, cost, and failure.

Hope that helps

-Adam
R247 Motorsports

 

[JadedSilver]

Another thing I should add to the post abot the ehad setup, is that with a dry sump you should just block all the oil returns to the block and setup a separate scavenge on the head itself.

It makes isolating the piston pairs down below less complicated. With separate scavenge pump stages for the block and head, there's no vacuum crossover between the two so it will eliminate the need to divide the head into chambers.

Retaining the reeds to limit vacuum draw on both the head nnd block can still be used, just separate reed blocks will be needed.

I probably should have posted that first as it basically "outdates" the first half of my original post/

-Adam
R247motorsports

 

[MNRaptor]

Thanks Adam, Using the separate pump stages just for the heads is what I was leaning towards, it does make the most sense. After talking with some of the local circle trackers, it sounds like a somewhat common practice. I am not sure what it would take to do the reed valves to control the vacuum. That is something that I am guessing will take more research. Thanks for the information, anything else that comes to mind, please let me know, there is a lot of work going into this setup, I really want it to be the best it can be.