944 NA Venturi Delete?

[thirty3]

Hey everyone,

Ive been searching the forums and the google for a good while about deleting the venturi on my 85/2 NA car. I'm reading lots about the turbo venturi delete, but not much on whether you should or shouldn't with an NA car.

It looks pretty easy:

1. Remove venturi with hose that connects to J boot fittings
2. Run brake booster directly into intake manifold wher the venturi used to connect
3. Cap off J boot fitting where the hose was in step 1

Will this put too much vacuum pressure on the brake booster?

Any help is appreciated. I'm afraid to try it and blow out the booster.

[v2rocket_aka944]

the 951 venturi delete helps get rid of a piping octopus under the manifold.
the NA system is much, much simpler.

basically the venturi Y pipe is there to provide vacuum to the brake booster and the HVAC system even at wide-open throttle conditions (autobahn).

you could do it as you listed. note that the 944S and S2 didn't have this system at all - the booster hose is just hooked to a nipple on the manifold.

[thirty3]

Originally Posted by v2rocket_aka944

you could do it as you listed. note that the 944S and S2 didn't have this system at all - the booster hose is just hooked to a nipple on the manifold.

That is great to know. I'm guessing that there is no change to the brake booster, meaning my stock one shouldn't be affected by the lack of venturi (which I think reduces pressure?).

Is that correct?

[v2rocket_aka944]

the boosters were the same. it won't be affected - the venturi is not a "vacuum limiter", like i said its purpose is to "generate" vacuum for the booster using the air rushing past the Y into the intake manifold at high throttle openings, to pull air OUT from the booster.

[thirty3]

OK great! I'll give it a shot tomorrow. I hope this improves my Idle issue. The car idles smooth when warm, but droops downwards of 100 rpms when the Alternator is loaded or the AC is on. It's also rough when cold.

I've replaced the ICV/ISV, resealed the AOS, replaced all the hoses under the intake, DME temp sensor, and it's down to the venturi and some emissions tiny hose stuff to sort through. The venturi looks unnecessary so I hope it works out well.

[djnolan]

There should be no need to do the delete. But the venturi has two pieces and there is an o-ring where the two pieces join. Check it carefully for looseness/leaks first. Also there should be a restrictor with clamp in the line between the venturi and the j-boot. If you replaced this line make sure you kept the restrictor. And make sure you have clamps on all of the fittings or there will be a bunch of small vacuum leaks that will add up to a poor idle.

[thirty3]

Thanks everyone, I went ahead and deleted it and the hose that connects to the J-boot.

The result was and even rougher idle, but I suspected that was due to less leaks. I reset the idle speed using the proper procedure, and the car now runs and idles better than normal and starts nearly perfectly without stumbling idle when cold. the economy meter looks correct as well. I think that's a good success.