vacuum booster resolutions

[jpavlack]

In an effort to clean up the engine compartment in the Ascona, I would really like to tear out that vacuum booster hose that goes across the valve cover. Summit sells a vacuum canister that holds reserve vacuum and an electrically operated vacuum pump that maintains a set vacuum level so you always have it working for you. It seems like a lot of unnecessary extra weight and electrical load to me. Is this worthwhile or is it safe to remove the hose altogether. How do some of you do this when you change to DCOE's, do you tap into the intake(I wouldn't like that)?

[jpavlack]

anyone?

[RallyBob]

When running twin DCOE's on a street car I always tap into all 4 runners for the vacuum booster. Tapping off one cylinder leaves a lot to be desired, it not only limits the vacuum available for braking, it can literally 'stall' out the cylinder that the vacuum hose is connected to.

I did a set of intakes for Neuropel a little while ago, tapping into both bosses, and drilling a hole between each pair of runners so the vacuum is shared by all 4 cylinders. Another net side affect is a smoother idle quality.

I have not used a vacuum reservoir or an electric pump before on an Opel, so I have no personal input on that matter. I've seen the reservoirs used on dual purpose street/drag cars however, seems to help when using a big cam with a ton of overlap and low vacuum.

Bob

[heimue]

Don't just remove the hose. You will loose most of your braking capabilities. You will have to step on the pedal way harder if you brake w/o booster. If you want to clean your engine compartment up, use a different hose (one that looks nice) and/or re-route the line around the engine.

Dieter

[PROPEL]

I use a vacuum reservoir on my big cam, twin-DCOM GT. I'm unaware whether I've ever stalled a cylinder, but I have the reservoir connected to the single Irmscher threaded port. My setup works fine.

I was just too lazy to take things apart again and tap all the runners, especially after getting everything to fit between the heaterbox.

[heimue]

Originally Posted by jpavlack It seems like a lot of unnecessary extra weight and electrical load to me. Is this worthwhile or is it safe to remove the hose altogether.

Baz,

that sounded more like he wants "to remove it altogether" - if possible.

Dieter

[baz]

Originally Posted by heimue Don't just remove the hose. You will loose most of your braking capabilities. You will have to step on the pedal way harder if you brake w/o booster. If you want to clean your engine compartment up, use a different hose (one that looks nice) and/or re-route the line around the engine. Dieter

dieter the thing he wants to do is replace the vac hose with an electrical gizmo not remove it and not do anything else

hth

[jpavlack]

I'm really looking at my options. I want to clean up the look in the engine compartment. As for braking without engine vacuum, I used to stop a 2 ton ford torino with drum brakes and no power brakes, so I can't imagine an Opel being more difficult to stop. I think I will just reroute the hose to back of valve cover. That seems like best option.

[blancojp]

You can always use a Neal Performance brake pedal assembly, two individual master cylinders and no vacuum required.

[heimue]

Originally Posted by jpavlack I used to stop a 2 ton ford torino with drum brakes and no power brakes, so I can't imagine an Opel being more difficult to stop.

The difference is, your Opel has front disc brakes, they are designed to work with a power booster. The drum brakes don't need it.

Advanced technical answer: The drum brakes don't need it, if they are designed as self-servo brakes. Here is a copy from Wikipedia (I couldn't have explained it better myself): "Drum brakes, depending on the way the shoes are hinged, can have a "self-servo" characteristic. This increases stopping power without any additional effort by the driver because the rotation of the drum drags the shoes around with it, increasing the force holding them together. In rear brakes (as illustrated above) only one shoe will have this characteristic. Front drum brakes may use two actuating cylinders which allow both shoes to utilize the servo characteristic and which also increase the front axle braking force, required to compensate for forward weight shift and also to avoid premature rear-wheel locking. Servo action can be used to make a very powerful brake (as on the rear axles of large commercial vehicles), but it does reduce the ability of the driver to modulate the brakes sensitively. (The disc brake has no self-servo effect because the pads act perpendicularly to the rotating disc.)"

Dieter

[blancojp]

That is a nice explanation however, it does not apply for this example.
You can stop a 3000lbs car with front disks and without power brakes very easily by dividing the flow/pressure requirements of the front and rear pistons/cylinders. After all, I posted all of the Opel brakes starting points for this purpose and I also showed how to install a manual master. I do this all of the time since most of our engines produce little or no vacuum.

The brake booster on the GT just barely increases 20-30% the applied force due to the 5:1 ratio of the pedal. If you calculate the required pressure at the brake pedal ratio you want, you can install individual or combination master cylinders to aid the pedal effort. I have 4 wheel disk brakes on my '72 and I use a manual Ford master cylinder with an approx. 16mm front/20mm rear pistons. It stops flat and pedal effort is slightly more than with a booster.

A Neal dual 5/8" master cylinder should be enough to stop a 2235Lbs vehicle with very little effort. Examples like these are all over the forums and you can benefit by just applying the formulas to your vehicle.