Crankcase evacuation

[b_have]

Guys, I am building a crankcase evac system, need some flexi pipework around 8~10 mm which can withstand downpipe temp at the connection. (I will be making a heatsink plate on the connector but still see around 500c)

Any ideas?

[Soonto_HAS_soop]

How flexible does it need to be? Can you not make a hardpipe or at least a section of hard pipe out to a flexible pipe?

[b_have]

Slash pipe will protude maybe 100mm from the downpipe with a heatsink, so maybe the hose will only see around 300C.

Was thinking of using the Aeroquip braided, but not sure of its heat resistance. Is there such a thing as Viton hose (as used for high temp o-rings?)

[TLicense]

Check thinkauto.com mate, they've got loads of info on the different grades of braided hose. Would be suprised if they didn't have something to suit.

[Tricky-Ricky]

Pretty sure i have seen the one way valves and hose kits that weld onto the exhaust, on one of the American sites, i'll have a look for a link later.

[spidermonkey]

what dia pipe do you need (I/D)

[b_have]

what dia pipe do you need (I/D)

 

10mm id would be ideal. Actually, heat may be only 200c as I will have to fit the slash pipe post wideband sensor, so will be in the midpipe.

[Lucifer]

Charlie can you not use some ali heat wrap, or is that a bit ugly?

[Digsy]

You're connecting your crankcase to the exhaust?

[b_have]

You're connecting your crankcase to the exhaust?

 

Yes, can create around 4psi vacuum with a slashcut pipe(Bernoulli effect) in the downpipe which will evacuate without contaminating the intake.

Been using slashcuts in Jetski pumps with good effect.

[Tricky-Ricky]

Link for exhaust breather parts, http://store.summitracing.com/egnsearch.asp?Ntk=KeywordSearch&DDS=1&Ntt=crakcase+evacuation&searchinresults=false&N=115&y=6&x=42

[Digsy]

Interesting. Sounds a bit like a race-only application, though. Are you sure it will create a vacuum under all "street" conditions?

[b_have]

Link for exhaust breather parts, http://store.summitracing.com/egnsearch.asp?Ntk=KeywordSearch&DDS=1&Ntt=crakcase+evacuation&searchinresults=false&N=115&y=6&x=42

 

Thanks Tricky, already have the Moroso system,trying to improve the efficiency. Think the slash pipes need to be in a venturi area of the exhaust to maximise the flow creating more vacuum.

[b_have]

Interesting. Sounds a bit like a race-only application, though. Are you sure it will create a vacuum under all "street" conditions?

 

In conjuction with the stock pcv it can only improve. This system is only effective at high rpm (which is where my c'case seal problem occurs) Have heard of people using electric smog type pumps, but reliability is poor.

[Lucifer]

Charlie,

 

I for one am watching this with great interest. Good on you.

[Tricky-Ricky]

Thanks Tricky' date=' already have the Moroso system,trying to improve the efficiency. Think the slash pipes need to be in a venturi area of the exhaust to maximise the flow creating more vacuum.[/quote']

 

Ahh right, yes i think you are right about that, i also seem to remember it needs to go pretty close to the turbo to get maximum gas speed?

[b_have]

Ahh right, yes i think you are right about that, i also seem to remember it needs to go pretty close to the turbo to get maximum gas speed?

 

Can't do that as it has to be downstream of the WB sensor. Would probably work best in a tapered restrictor ring acting as a venturi. Using a 4" HKS TI pipe so can play with flows a little

[Chris Wilson]

With repect you are tryng to fix a problem that shouldn't be there. the ctrankcase can only pressurise through blow by, you should be looking at the bores and pistons and making sure you have as little blow by as possible, forget any PCV or smog stuff. All IMHO.

[Lucifer]

As usual you are correct Chris, but as you know not everyone has the facilities and or money to do that. This may be a cheaper way to patch up the excessive CCP.

[b_have]

With repect you are tryng to fix a problem that shouldn't be there. the ctrankcase can only pressurise through blow by, you should be looking at the bores and pistons and making sure you have as little blow by as possible, forget any PCV or smog stuff. All IMHO.

 

Maybe so, but having checked bore/ring wear when the engine was apart, found it to be within oem tolerence. This problem has only become apparent above 1.6 bar/7200 rpm.

Would be interetested to know how you overcome this problem Chris? or have you not stretched a 2JZ that far?

[dandan]

Charlie,

 

I may well have some useful info on this at home that may be of some use (although sounds like you're familiar with the idea already). I'll dig it out and if it looks any good I'll let you know.

 

I have used coiled copper pipe in the past to reduce temps enough for flexible connection...

[Chris Wilson]

An engine is an engine, Nissan, Toyota, Ford, Coswoeth, Judd, whatever. Are you on forged pistons? 1.6 is a LOT of boost. If you are on oversize bores the block may be balooning, there's not much wall thickness in the stock blocks, most modern lightweight cast iron road engine blocks have a minimal amount of wall thickness, for weight and material cost reasons. Nissan addressed this with a GT block, for the GTR engines, with a couple of mm extra wall thickness in the bores to add stability at high cylinder pressures. This overcomes a simialr weakness in their stock blocks.

 

If you are on cast pistons the thermal stresses may be making them more oval or barelled than stock, and causing poor ring sealing. Whatever, excess blow by is always a sign of wear, or execess pressures for the design of the bores, pistons or rings, assuming no excess wear, or physical damage.

[Digsy]

Also the piston rings may be fluttering because of the elevated rev limit, too. Ring sealing isn't a static condition, but a dynamic one and its not all down to limits and fits.

[b_have]

All oem (except arp bolts) so i guess I'm reaching the limits. I think the cc evac idea is a no lose situation so will give it some testing. BTW, everything else looking good at these boost/rpm levels, no blue smoke, no det and feels pretty quick

[b_have]

Charlie,

 

I may well have some useful info on this at home that may be of some use (although sounds like you're familiar with the idea already). I'll dig it out and if it looks any good I'll let you know.

 

I have used coiled copper pipe in the past to reduce temps enough for flexible connection...

 

Cheers Dan, trying to find more info on the Bernoulli effect of slash cut pipe. I'm using a Morroso evac system (cam cover fittings and non return valves) but going bigger on the slash cut pipes and maybe using multiples. Any info most welcome.