Reasonable cost (NOT cheap) street flathead engine.

[Tim Ayers]

Lightening the crank is actually very cheap because you can usually do it yourself as long as you understand the basics, BUT, it will generally add to the cost of balancing due to additional machine work.

Yeah, I'm going to give it a try next go around.

 

[Pete]

I see 2 items that I don't recall being discussed here - the dry sump and the heads. I'm very interested in how well the filled chambers work.

On an all out vintage circle track engine we get well over one hp per cubic inch.

 

[Bored&Stroked]

I see 2 items that I don't recall being discussed here - the dry sump and the heads. I'm very interested in how well the filled chambers work.

There are a couple things to note in Pete's post:

1) The dry sump is something that is combined with low-tension total-seal or metric rings. The goal is to reduce reciprocating friction and overall "oil drag" in the lower-end. You need enough "stages" in the pump to really pull oil and create a vacuum inside the engine.

2) On a full-on racing engine, some may add a vacuum pump as well.

Obviously in order to run a dry-sump setup, you also have to have a dry-sump reservoir.

The combination of a correctly designed dry-sump setup, low tension rings, oil scrapers, windage tray, etc.. - results in the important extra horsepower Pete was talking about --> I believe he referenced 40. That is a LOT in a flathead - so you can see the value in all of this.

3) On filling the heads, I believe what he is talking about is to fill/remove the dome and run a flat-top piston with a tight quench.

In days past, one could get some of the head manufacturers to deliver heads without any of the dome work done - so you could do what you want --> run a flattop, run a pop-up flat-top, etc.. Not sure if one can get anybody to do this today, but it beats having to TIG weld the heck out of a "normal" head to get there.