Miata Turbo Forum - Boost cars, acquire cats. - Slash cuts, whos got the info?

- Engine Performance (https://www.miataturbo.net/engine-performance-56/)

- - Slash cuts, whos got the info? (https://www.miataturbo.net/engine-performance-56/slash-cuts-whos-got-info-74425/)

I really don't think you want to return to sump in that fashion. Catch cans, and all that steel wool will act as a wonderful condenser, condensing the water vapor out of the blow by gasses and then dumping that nice oil/water mixture back to the pan along with whatever unburnt hydrocarbons the catch can/condenser has managed to collect.

At a minimum it needs to be heated by the coolant.

Yeah its unlikely to get returned like OEM does it, Ill just use a tap.

Dann

Unless you have that tank above the valve cover it wont run back. You will however get a bubbling effect that should splash oil up the mesh to increase its efficiency. Clumped oil is good, fumes on the other hand will go straight out the exhaust.

Also watch out with steel wool. I've heard of it breaking up and finding its way into places it shouldnt. Supposedly the brass wool is better, its what I used.

Sweet.

So it occurs to me that if the exhaust pressurises you will quickly end up with a system no better than stock.

You can run a check valve, but then if it closes the engine will just pressurise the catch can.

Any ideas here? There really isnt a lot of info out there.

Im also concerned about the cat... Any feedback?

Dann

Fae saw this thread and sent me an email. I wasn't going to post it because Dann is a lying douche canoe but since others will probably stumble on this thread, here goes:

Quote:

Saw the thread. https://www.miataturbo.net/engine-pe...ot-info-74425/

Here's my report:

I used the stock baffling and ran 2x -12 lines from the exhaust side of the valve cover to the slashcuts directly. The center and exhaust baffles were retained, with the connecting passage hole enlarged. I used Moroso slashcuts and Moroso check valves. After a few hundred miles or so, the check valves no longer worked. When the car was idling, I can feel exhaust coming through the hoses. Fail. The slashcuts do work- I know this because I measured crankcase pressure by attaching a vac/boost gauge to my oil cap and saw negligible pressure under 30+psi of boost. Also, if I just rev up the car with it standing still I feel vacuum on the hoses. Annnd I also know they work because my exhaust has tarrish buildup lining it after the slashcuts. Unfortunately, after a long cruise, like over half an hour or so, the exhaust heats up and the tar starts to smoke making it look like I lost a piston. Fail.

One's crankcase evac solutions should be dictated by a) how much boost you are going to run and b) how you are going to use the car. For a low boost under 10psi car, assuming you use the baffles and don't have compression issues, a slashcut may not smoke very much. For a low boost car, why even bother. Just run the stupid crankcase vent line to the intake and be done. Yes the oil will lower the detonation threshold but who cares cuz you're not making allofit HP anyways. Note that many drift cars run slashcuts and you probably don't notice the smoking exhaust because of the holocaust of rubber smoke.

Really, I think it was a waste of time and money. If I do-over I would do it like high-hp hondas and gangrape the valvecover with 4x -8 lines and send them to a gigantic catch can box with 4 breathers or something ridiculous. Something like this NEW ANODIZED & POLISHED CATCH CAN KITS!!!!!!!!!!!!! - Honda-Tech

I don't think the bump-in the line valvecover-catchcan-slashcut will work. The slashcut will suck the moisture out of the can.

Faefae

I actually agree with most of it and give him props on a nice review/summary.

props for your sense of humour and help :)

I was thinking 2x3/8 hoses from the hotside of the cam cover and PCV valves on each of them and then the hose directly out to the exhaust with no valve there.

Thanks,
Dann

Check valves are very hard to find with low cracking pressure GRR.

Any ideas what else can be used?

Dann

Make a flapper door?

Ok Im putting one of these check valves on, and modifying the spring to give a lower crack presure.

http://liveimages.quicksales.com.au/...adcolor=ffffff

Customers happy to pay for what it takes to build the ultimate catch can setup and test it, Im doing it for cost because i wanted to learn and offer a really good catch can solution specific for NA/NB chassis, so this is a good place to start :)

Can anybody think of a cost effective solution to view oil level without paying huge money or using that god damn useless shitty plastic tube like most cans have.

So far the idea is a 1" alloy cap with an alloy tube below it so you have a clear section of the can without the steel wool blocking your view.

https://www.miataturbo.net/attachmen...ine=1377138160

http://s13.postimg.org/t7szal5yv/Catch_can.jpg

Dann

So catch cans.

I dont want photos of cylinders with pipes in them , I meant internal design, where the hoses go, how the baffles look etc.

I'll do it all and post results and everyone gets a bit smarter. :party:

Dann[/QUOTE]

Here's what I did in my build thread. I addressed engine block venting and modified a cheap catch can from ebay. Refer to posts 4,9,26.

https://www.miataturbo.net/build-thr...-thread-70913/

Props awarded for info.

What model is the 1 way valve from?

From the honda.

Dann

Just confirming that this is the exact same spot bbundy and the others who are doing twin ventilation from this side are using?

https://www.miataturbo.net/attachmen...ine=1377159877

thanks
Dann

Cost effective solution to view the level would be a screw in site hole. Its just a piece of clear glass or plastic that fits through a hole with gaskets and some threading, like a bulkhead fitting. Should be able to get them from an industrial supply place.

Yeah available on ebay.

Dann

It'll be called a sight window or something like that. Doesnt upsidedown land have something like mcmaster?

I edited, and yeah we do but its all WAY overpriced.

Cos we have too much goddam money here.

Dann

Lol, I can get them for like 6 bucks. McMaster-Carr Not sure if that link'll work mcmaster and linking is iffy.

I can get them shipped from china for a similar price, thismay be the go.

Dann

Did you check Australasian ebay? If not, maybe buy a shitload of them and mark them for some price between the crazy local price and the china price and make some extra dough.