Gimme a Boost: How to Build an Inexpensive Power Brake Vacuum Booster

Gimme a Boost: How to Build an Inexpensive Power Brake Vacuum Booster
Words By: Jeff Smith
Photos By: Doug Eisberg, Eric Rosendahl, Jeff Smith
What ’ s the inaugural couple that pops into your headway ? The great ones will always be great — peanut butter & jelly, Abbott & Costello, and possibly Captain Kirk and Mr. Spock. A far less effective duet for a street car is a big cam and world power brakes. High overlap camshafts combined with office brakes much create a hard pedal that makes it unmanageable to stop at slowly speeds, where the engine vacuum good can ’ thyroxine add the needed boost to make the baron brakes effective .
Eric Rosendahl and his long-time compatriot, Doug Eisberg, shared this common affliction. Doug ’ s 496c.i. Rat-motored Nova was built as a Q-ship — a poseur — masquerading as a stock 396 Nova. Eric ’ s approach was to dump the wimpish small-block in his ′66 El Camino in favor of a 468 iron-headed Rat that makes 580-plus lb-ft of torsion. Eric ’ s name may sound familiar ; we used his rat as our test mule for installing a hydraulic roller cam ( “ Let It Roll ” PPN ) followed by a comparison of a three of hydraulic roller cam ( “ The Duration Game ” PPN ). Both of these previous stories can be found at

Both cars had similar brake performance issues. The first gear application of the brake pedal produced acceptable brake performance. But at low vehicle speeds, if the bracken pedal was applied more than doubly in flying succession with the engine near idle in gear ( both cars are automatics ), the pedal point campaign cursorily deteriorated into what could well be a dangerous position should a panic diaphragm be required .
While resorting to manual brake was an option, both decided that what was in truth needed was extra vacuum assist during abject speed situations. Eric performed hours of research and discovered a GM factory vacuum pump for a 2011 V6 Cadillac CTS that was designed to perform this demand task. even better, the vacuum pump was low-cost at well under $ 140 from either RockAuto or Summit Racing. After coming up with a suitable test plan, Doug bought this pump, and the pair decided to test it on Doug ’ s Nova .
The specification we found from Hella do not recommend this product to be used as a primary source of vacuum for a might brake unit of measurement, although it is the accurate same pump used by Cadillac. In this case, the pump is not the sole source of vacuum serve. The guys are using this pump to supplement engine vacuum supplied to the vacuum reservoir. The specification on the pump offer an engage life of 1,200 hours at 1 million cycles, operating at a draw of less than 15 amps when supplied with at least 13 volts. This sounded like sufficient lastingness. The question would be how it would work on the street .
Besides a heart, the design demanded other consort components. From a baron point of view, the pump would require a 30-amp relay to supply ability. Next, a specific void detector switch would be required to sense a gloomy vacuum to trigger the heart. A crude alternate would be to operate the pump any fourth dimension the brake light interchange was engaged, but this would place a much greater demand on the pump than necessity, particularly with the addition of a void reservoir. Eric found the vacuum switch through Stainless Steel Brakes at Summit Racing for less than $ 35 .
Doug ’ s locomotive idles with between 9 and 10 inches Hg of manifold paper vacuum in gearing, so this application would ask the pump to increase the vacuum to approximately 18 inches Hg. By adding the void reservoir, this does not increase the vacuum, but does increase the volume as a condom bill for greater capability than just the little book found in the promoter itself.

Eric besides reasoned this system might ultimately be safer than early hike systems. In a distinctive engine-fed world power brake system, if the locomotive were to stall, the driver would have one to possibly two brake-assists before the pedal point attempt would drastically increase. With a hydro-boost system, if the engine stalled, the like consequence would be generated. With this electric drive vacuum promote arrangement, if the locomotive dies but the ignition power remains on, the electric pump will inactive supply vacuum serve to the brake pedal, a long as the battery offers sufficient electric potential .
Armed with this approach, the guys decided to first test the AC Delco Caddy pump on Doug ’ s Nova by temporarily bolting it to a wood base to the driver side fender and plumbing it in between the engine and the power brake booster. This initial screen was run without the add bulk of the reservoir, but the results were impressive enough that they then decided to build a permanent mount for the pump and reservoir .
As we mentioned earlier, Doug ’ s thing is to keep his Nova adenine stock-looking as possible. So the pair built an aluminum bracket to mount the pump and the reservoir underneath the driver presence buffer and above the inner fender well, using longer bolts from the hood hinge as stud to mount the bracket. They oriented the pump horizontally, both for headroom and besides to minimize the burden on the pump, although Cadillac locates the pump vertically with pump end up. They besides bent lengths of 3/8-inch tube and connected the lines with vacuum hose and clamps .
With the system in rate, they were besides concerned with noise, but that besides turned out well. With the pump in space and run, they used a meter to measure the sound at 64 dubnium from two feet away with the hood closed. This is equivalent to normal conversation in a restaurant. then, yes you can hear it when Doug first base turns the ignition on, but once that gnarled big-block fires up, the noise is completely masked .
Test drives with the Nova promptly revealed Doug immediately has brakes like he hasn ’ thyroxine experienced in years. He can apply the brake bicycle multiple times in agile sequence without an increase in bicycle feat, and the car now stops in a much shorter distance at abject speeds with convention pedal point effort. At this bespeak, Doug has roughly 300 miles on the organization, but he is thrilled with the box and now, Eric is assembling the parts to perform his adaptation of this system on his big-block El Camino.

Xem thêm: Wikipedia

therefore, if your older supercar is suffering from the high bicycle effort from exponent brakes, ascribable to low engine vacuum at humble speeds, this just might be a way to make the cable car both more fun to drive and safer at the lapp time. And you can do it all for $ 250 .
Sources: RockAuto ; ; Summit Racing,

reference :
Category : Car Brakes