This should go in either the "talk me outta this" thread or in the Turbo forum, but I need an answer by Wednesday morning.

How the 'ef do you plumb a turbo engine for power brakes?

Details: engine is a draw thru setup, so the turbo draws thru the carb and blows right into the intake manifold. The manifold, a Clifford, has taps on it that I have hose fittings for, but if there's positive pressure in the manifold wouldn't it make the power brakes inop? The carb has a big nipple on it currently plumbed to the PCV valve - should I hook the power brake hose to that? Would it be okay to T off the carb nipple and run the PB and PCV together?

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1965 Valiant wagon Turbo slant (work in progress)
2000 Chevy 155" cargo van - The Abductor
1970 Newport convertible
1996 Buick Roadmaster Wagon
1966 CruiseAire motor home
1990 Toyota 1 ton box truck TURBO slant (scraped)

I dont personally have power brakes and I could be wrong but by theory power brakes work off the engines vac so they would work until your under boost so they would not work as far as I would think yet newer turbo cars have working brakes but they might not pull from vaccum like yours do sooo dont' really know i'm sure someone will chime in who knows the answer or who has done this before.

Kev

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Auxiliary vacuum unit. I believe you can buy electric vacuum pumps specifically for this sort of application. I know cars converted to electric motor use vacuum pumps to retain the factory power brakes.

Don't do it though.

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Casually looking for a Clifford hyperpak intake for cheap.

The vacuum booster stores vacuum. The valve which pushes into the booster is a check valve and, if it doesn't blow up under boost, should hold the vacuum just as it does with a normally aspirated engine. Use the port on the manifold near the carb. Keep the PCV valve connected to the carb, but put a check valve in line so you don't feed air and fuel into the crankcase under boost.

<edit> Oops, I missed that this was a draw through setup. Ignore the check PCV check valve comment.

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Joshua

Between the turbo and carb,but I agree with josh, draw through turbos are great under W.O.T. but suffer part throttle drivablity problems,blow through turbos (like mine)work fine during normal street driving,but are a buzzard to tune under boost.I have manual brakes.Just be sure your turbo seals can take the vacuum during coast,diesel turbos (like mine) generaly can't.

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V8?? We don't need no stink'n V8!!

With a draw thru, hook the PVC and vacuum booster line up between the carb and the turbo. The existing PVC location should work for both.

Should always be at or below atmospheric pressure, so you don't need a check valve.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Between carb and engine, there will be vacuum at small throttle opening and idle. When turbo comes on boost, it will pressurize the vacuum stuff, hence the need for check valves.

Cheers, Wizard

The PVC and brake line are before the turbo, so there's no pressure......

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Just a FYI. A PCV valve actually has three functional operating positions. At high manifold vacumm, the internal "shuttle" valve is pulled into a position that has a restriction, to prevent a large "vacumm leak". At low vacumm conditions the internal shuttle valve is pushed into position by the spring, and allows air to "bypass" the restriction. This allows a larger flow, at lower vacumm. The third position, is totally closed, as when the manifold would have pressure, rather then vacumm, such as if the engine should "backfire" into the intake. This same feature will allow a PCV to be used in a turbo installetion, without modification.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Man you guys are good!

I'm going to T it into the PCV line coming off the carb. Since it goes carb, turbo, manifold there should always be some vacuume at the carb as long as the engine is running.

But I didn't know a PCV valve was also a check valve in the event of a backfire. It's a "blowout preventer" or "BOP". You learn something new every day.

Tommorow is another day, a day in which I will re-install the engine and fire it up. I'll post the results back in the main message thread.

Thanks for the quick replies!
Kip

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1965 Valiant wagon Turbo slant (work in progress)
2000 Chevy 155" cargo van - The Abductor
1970 Newport convertible
1996 Buick Roadmaster Wagon
1966 CruiseAire motor home
1990 Toyota 1 ton box truck TURBO slant (scraped)