Vacumn Pumps

[wheelrdealer]

Leadfoot:

We were curious about a vacuum pump too. We just did a dyno test with my old school "D" motor 302 SBC. 3" stroke, 4" bore, AFR heads, tunnel ram w/ two 650's and a big cam, VP 110. We tuned the motor to 472.3 HP at 8,000 without our a vacuum pump. Put the belt on and made 492.1 at 8,000 RPM for an honest 20 HP. Aerospace Components 4 Vane pump 16.9 Ins vacuum which is high. We did not pull any oil into the pump and oil pressure stayed at a steady 90 PSI so it did not appear the pump was keeping the oil away from the wet sump pick up.

Horsepower had not fallen off up to 8,000. After 19 dyno pulls we decided to take the engine off the dyno, drop the pan and check everything before we moved up to the 8,400 pulls. It was still making about 3 HP per 100 RPM at 8,000 so in theory it could make a little over 500 at 8,400. We also had #7,#8 running a little rich so there may be a tiny bit more power in the carb tuning.

BR

[manta22]

BR;

8400RPM...what kind of valve rockers are you using?

Regards, Neil  Tucson, AZ

[Rex Schimmer]

BR,
Great to have some "real" numbers as to what a vacuum pump is worth in real horse power. Your wet sump engine must have a very efficient and deep pan an oil recovery system. Thanks for the report, another real number we all can use.

Rex

[Leadfoot]

Thanks BR thats some good numbers should be even better on a larger cubic inch engine. Gary

[Leadfoot]

Where did you plumb the suction side Valve cover ?

[jimmy six]

I've used both pan and valve cover and reccommend valve cover. Make sure you have some type of deflector under the fitting to deflect the oil. Mine is attached to the rocker arm assembly.

[wheelrdealer]

Yes, welded two -10 bungs to each valve cover. One -10 an to the suction side of the pump and the other side we attached to the Dyno vacuum port. We did not see it pulling any oil. Not sure if we just got lucky.

Valve train is a Clay Smith cam, Comp Cams roller lifters, Scorpion rockers 1:5 exhaust, 1:6 intake, Comp Cams stud brace. Comp Cams lifter retainer.

BR

[toclub]

No oil in the vaccum pump is not OK. At the salt in 5 miles you will fry that pump. Put a couple of squrits of  oil in the pump before every run.

[wheelrdealer]

I might have mis-spoke.

When I said no oil in the vacuum pump I meant it was not picking up large amounts of oil from the valve cover and discharging it out the discharge side of the pump. It was picking up some mist and had an oily film but was not sucking oil out of the valve cover. We had heard that vacuum over 12 to 14 on a wet sump could hold too much oil up top and starve the pump. We never saw any indication that was happening. In fact, the motor always has made a lot of oil pressure. It has a Melling billet pump and made about 90 PSI at Bonneville. We used 20W50 and it made at times 100 psi. Seems we can drop the viscosity down some. 

I will use your suggestion and put a few squirts of oil in the pump before I make a run.

Tomorrow at work, I'll scan both dyno sheets and post them. 

That's why I like this forum. I always take away some good advice or ideas.

BR

[Freud]

The fortunate 'idea" is that you have found some time to work on the car.

I think you have been missing that.

FREUD

[manta22]

Thanks, BR. I was assuming that you used some sort of shaft rockers for that high RPM.

Regards, Neil  Tucson, AZ

[wheelrdealer]

Doc:

I actually got the front suspension installed last night. It is good to have a roller again. Waiting in a new release bearing and the engine and trans can go in. Not a record capable engine but it will let me go to a few mile events and shake down the new modifications.

BR

The fortunate 'idea" is that you have found some time to work on the car.

I think you have been missing that.

FREUD

[GD]

BR,
Great to have some "real" numbers as to what a vacuum pump is worth in real horse power. Your wet sump engine must have a very efficient and deep pan an oil recovery system. Thanks for the report, another real number we all can use.

Rex

Here are some more real numbers for you Rex. I wish I  got the same results as BR. I just finished 3 days on the dyno - testing and tuning my 295 cu in Flathead Ford. After establishing a baseline 230hp @5500rpm on gas, we hooked up a brand new Moroso vacume pump. Max hp with vacume pump was 229 for a loss of 1hp. Scrapped the idea of the vacume pump. Went on to test with Methanol. Made 250 hp with Methanol and 260 hp with 10% Nitro. I think I will start in XF/FCC at Speedweek this year and maybe switch back to gas later in the week. See you on the salt.
Gord Driedger

[Leadfoot]

What is a good baseline to run the pump...10 -12 inch ?

[wheelrdealer]

We were told by the engine guy 12 to 14. On the first pull we guessed at the setting and the engine vacuum was 17.1 and made 20 HP. We adjusted it down and at 14 we gained about 12 HP. Adjusted it back up to 16 and gained 19 HP.

The engine had some interesting responses. It shows rich on the EGT's and O2s but when we leaned it out some the HP dropped dramatically. The carbs are not the best so some of the rich may be the carbs.  It also responded to a lot of timing somewhere around 36 degrees of total timing made the most power. In addition, we ran 20W50 and the difference between a starting oil temp of 177 and 195 was 15 HP.


BR

What is a good baseline to run the pump...10 -12 inch ?