Inline turbo PCV setup?

The turbo 250 project is now finally on wheels and spools up' nicely but has serious blowby-blue smoke out the breather when boost builds. Trying to figure out how much is from the condition of engine and if PCV could be better implemented to limit the blowby. The turbo oil return currently dumps into valve cover and does pump a lot of oil at higher/boost RPM's into valve area, maybe affecting it?.

... Are 'turbo' application specific PCV's different?

'appreciate a discussion on how best to handle crankcase venting/evac. with turbo. Possibly use a catch-can for separating oil from vapor ?., some high-end setups use a vac' pump but hoping for simpler solution.

thanks and have fun

Nice setup!

Quick question, does your turbo have a carbon seal? When running a turbo draw-through style, the turbo is introduced to vacuum since it is between the throttle plate and the engine (vs in front of the throttle plate in a blow-through style). The seals in a normal turbo are not meant to handle vacuum and therefore will leak oil into the intake. I know this doesnt match up with your symptoms exactly but it may be related.

My oil drain runs into the oil pan but I've never heard of anyone having issues dumping into the valve cover (although I personally still wouldnt do it). Also, you say its blowing blue smoke out the breather? You sure its not coming out the exhaust? Blow-by usually just blows oil vapor out the breather, if its blowing blue smoke then its burning the oil somewhere, possibly in the intake but then it'd be coming out the exhaust just as heavily.

thanks for the reply:
.. quick answer is the Garrett/Air Research TBO-3 turbo is specific to OEM draw thru BOP setup I grafted onto the 250 Ford. The The turbo works in concert with The specific Rochester 4Bbl Quadrajet which has external PV port and non-symetrical AFR log. You're correct - closing the carb throttle causes very high vac' at the turbo, it has to have seals for pressure and high vacuum ... . (Many racing draw-thru setups used a second throttle/ diverter to bypass fuel feed and relieve vacuum, it would open as throttle closed. [kudos MacInnes'])

Replaced the PCV with a turbo application, after some more driving and boosting the blowby is reduced but confidence in the current engine is not improved. I used the current engine to fit car with a 'turbo built' 250 ready to install. Ordered an electric fuel pump which will enable the oil return to dump into mech. FP location. At mid rpm's the turbos' oil return line returns a lot of oil considering I use a 3/16" brake line as reducer to turbo oil feed to keep pressure in check and from pumping through turbo seals.

I used my '61 Comet 250 for dimensions when I started build but now fitting turbo in a '74 Maverick 250 . I found the early cars fender and hood were much higher than Maverick at shock towers and may use a shorter 200 if I keep the draw-thru in the Maverick. I have a parts Mav' also and the 200 sits a good 3" lower than 250 at the firewall and towers.

have fun

Yeah I figured you'd done your research on draw throughs by looking at the setup.

How about an oil restrictor? I used 3/16" brake line for my feed and added a 0.060 restrictor, well actually I filled the fitting with solder and then drilled a hole with a 1/16th drill bit but it achieved the same end result. Depending on the seals, oil drain size, etc. etc. you could be pumping waaayy to much oil through the turbo and also onto the rockers in the head. Also can you confirm your oil pressure.

You did it! Well done my friend! 8)

I ran a simple pcv valve and breather in my blow through. It worked fine after I discovered that the 2 dollar junk from Autozone doesn't check under boost and I replaced it with a 10 dollar motorcraft pcv valve from the dealership. The application was for a Tbird Turbocoupe. Worked like a charm. Until I blew it up hahah.

You drive it yet? 8)

First Fox":2umzqq5d said:

... You drive it yet? 8)

Click to expand...

YES I drove it !, I should say WE because we did it with the advice and encouragement from forum friends...

I used the existing tired 250 in the Maverick to fit and finish the turbo setup and instrumentation.Started right up and actually idles and runs pretty good.

My first test run before modifying ignition timing I found boost builds at mid throttle and reveals a powerband where the 250 had run previously out of oomph. But I succeeded in blowing the muffler apart:


After limiting timing to a maximum @ 26 degrees with the DS-II's existing advance plate and sourcing vac advance off manifld vac/press it runs great with no detonation. Still needs transition from cruise to boost tuning but AFR looks fairly safe overall.



.

I'm working out a hood/bonnet for the setup and road-readying the car for more fun. Once weather permits I will get to properly assess next steps toward going fast-safely ...

have fun

That's great Rich, I look forward to more updates!

If you don't mind some constructive criticism, I would tell you that your drain line will give you trouble without a doubt. As long as you are just cruising it will be fine, but when you start making boost for extended periods, that return line will back up with oil due to the angle of the hose, the seals will be overcome and will immediately fill your rear view mirror with the thickest smoke you have seen unless you have previously blown and engine haha.

The line needs to be almost vertical into the oil pan with very gentle bends or it will back up for sure. The deal is, when spooled up at high turbocharger RPM, the oil through the Turbo bearings gets totally combined with air believe it or not, and actually looks like brownish whipped crem whem it drains from the turbo. This stuff will not flow down a near horizontal return line. I like what you've done with the valve cover drain and I think you have the carb height to make that work, but when that return gives you trouble, you can probably make it work by using a huge return line and running it the way you have now. I mean an inch or better in diameter.

Quadrajets are not that hard to tune, you will need jets and metering rods and they are very available and can be changed while the carb is on the car.

So glad you got it going bro!

The turbo oil return line into VC may be affecting tuning , just received an electric fuel pump (carb type Carter 4-8 PSI) and want to send oil return to OEM mechanical FP location unless some advantage to return to side of pan,what about 'catch can's ?. I never ran an Elec Fuel Pump and thought I'd just bolt it in under the hood. Now find need for switched relay power, wiring, and advised cut-off safety switch, and mounting OUTSIDE engine compartment.

The whole Buick setup includes the turbo-specific Quadrajet with external Power Valve port. There is a remote vac valve permitting Q'jets' upper carb ported vacuum source to keep PV closed until manifold 'loses vac' / transitions to boost which shuts vac circuit - opening the Power Valve. The circuit lets PV add additional fuel with boost at manifld and not kept shut from high vacuum at draw-thru Qjet . The Qjet secondaries operate mostly with calibrated vacuum , on test stand, they would not open more than a crack. Driving the Maverick, as the turbo spools up under load there is a transition where the Qjet secondaries open wide and the available fuel gets blown thru to detonate or the anvil like old six gives a new experience.






have fun

I got the turbo' 3-OTT Maverick's AM radio working but used the heater hoses for turbo plenum so it's been too cold to get out. Used a parts' Comet GT scoop hood for something better than no hood at all, could use brakes, shocks, better tires , T5, ...