Haraise

I know the 20B's oil pump won't hold pressure to 9k, anyone experimented with scanning the parts and making new guts with a CNC that would flow better? Why/why not? Seems far simpler than a dry sump and is common in other cars.

stickmantijuana

iTrader: (1)

nobody has oil pressure issues or better yet lubrication issues with rotaries. I'm sure there are exceptions, but they are exceptions to the norm.

t-von

iTrader: (8)

For normal use the 20b's oil pump is fine but, it won't hold pressure above 8,500rpms. It runs a standard 3rd gen oil pump. I personally can't run my NA 20b up to its potential due to the lack of oil pressure. I would love for someone to make an upgrade.


Had I had access to the machinery, I would have done this year's ago. Op you have something in the works? I think you would have many buyers provided it's a quality test proven unit. If you go with the same diameter gearing, you would have to make both internal gears taller to give more surface area to push more oil. Also if it's taller, the housing would still have to clear the front cover from being taller overall. I also have a way to test the oil flow of the stock pump if you need me too? I have training in hydraulic fluid dynamics.

Haraise

I don't have anything in the works, no. Just see a gap in the market that other vehicles generally have covered, and was surprised no one has acted upon it.

There seems to be low hanging fruit in just redoing the internals with modern CNC work and appropriate metal, increasing the diameter within the stock unit by taking the internal diameter up, but I agree that the optimal solution would require a new housing, but I'm unable to model the flow of what increasing the diameter of the internals within stock housing would do as far as how much more 20B RPM it could support.

j9fd3s

iTrader: (3)

there is room to make the pump a little bigger, but your limit is the land on the front iron, its only so big.

actually if one were bucks up, the SII Rx8 oiling system might be the thing to do

Haraise

Do you have any information on how the S2 oil pump differs? I know it provides higher pressure, but I haven't seen pictures of the internals.

j9fd3s

iTrader: (3)

Haraise

So if the front iron differs, they could be putting a wider or deeper pump in there. That'd be interesting to find out how it actually differs.

Has anyone tried a Renesis pump on a 13B?

t-von

iTrader: (8)

I don't think an S2 Renesis pump will work as I think it's guts are the same size as the Fd's. The S1 Renesis oil pump is virtually the same size as the 2nd gen Rx7 NA's. Unfortunately Mazda stupidly backtracked and decided to use this same pump in the 1st Renesis. NA street engines don't experience the bearing loads of a boosted engine so it makes since why they did it.

Here you see the fd on the left and S1 Renesis on the right. Both are the exact same diameter but the Fd is 11/16" thick while the Renesis is 1/2". This less surface area is the main reason the S1 Renesis was lacking in flow. Less flow creates less pressure under the same restriction (which is what causes pressure buildup). Since the auto tranny lowered the 20b's red line, Mazda was able to re-use the same Fd pump on the bigger engine. Too bad the 20b wasn't available with a manuel as we would most definitely have what we need from a factory setup.

Haraise

Thank you very much for that detail, I really appreciate it, t-von.

I know the S2 is running more pressure, why do you believe the guts are the same as the FD?

j9fd3s

iTrader: (3)

they did more than change the pump guts for the S2 renesis, they also simplified the passages in the front of the engine.

this is nit picky, but they used the 20B pump in the FD, and not the other way around, 20B came before the FD.

t-von

iTrader: (8)

Not nit picky at all. I keep forgeting that the 20b Cosmos came out in 1990. This explaines why the 3rd gen pump has been so robust.

t-von

iTrader: (8)

Some research I did a few years back where someone was explaining that the internals were basically the same. I can't seem to find exactly where I got that info. I found an S2 pump on eBay and contacted the seller to see if they would give me some dimensions on the gears but, haven't heard back from them.

Haraise

Great detail on the providence of the FD oil pump, thank you!

And I really appreciate the effort in looking for the S2 specs, t-von.