Great thread guys!!!

Mindgame, as for my engine, it will probably be a bracket racing engine for now. Maybe run a few PRO Pro Stock races. This engine is a proving ground for me. This is my first attempt at such an engine, as I've never run aluminum rods, titanium valves, almost 0.800" lift, or and external oil pump before. I have a bowtie block in the corner that will eventually be built, once I do my learning with this engine. I will probably go with some 15 degree heads, maybe even some All-Pro 13 degree stuff. Haven't decided that, yet. I've thought about the SB2's, but their really not my cup of tea. I kind of prefer the inline valve stuff personally. To each his own, I guess.

Stephen, myabe I'm misunderstanding you. What I was trying to say is I have actually connected a vacuum guage DIRECTLY to the inlet of the electric "smog" vacuum pump, and it will only pull 5"Hg. This was a direct connection, no crankcase or extra airflow included. Otherwise known as "dead-headed". Again, like I stated, it is incorrect to say that ANY vacuum pump can pull 28" Hg, even dead-headed. It depends upon the design of the pump; internal tolerances, positive displacement, pump rpm, etc. I can take an aftermarket Moroso vacuum pump and turn it 5 rpm and it will not pull 28" Hg. I will pull 28" Hg at a higher rpm, but hopefully you understand what I'm saying.

I invite anyone that has the oppurtunity to tear one of these electric smog pumps apart. You only have to pop the plastic cover off, and it is fairly simple. There is some foam in the way, but once you remove it, you will see how crude the design is. It works well for it's intended application, but it was not designed to pull crankcase vacuum. You can look through the hole in the case and see the little vane impeller. Looks similar to a water pump impeller. Not a very efficient design for pulling vacuum.

Anyway, great thread guys!!!

Shane

 

No mater what way its driven the energy is taken form the motor . The lesss effecient way from the alt to the motor driving the pump vs. just straight from the crank to the pump. Also theres less parts to break. Either way i you have an increased output at the crank its worth it. Its like superchargers they take hp to make more hp out of it.

 

I've been runing the same type of electric vacuum as Prostockjohn mentioned, from a 4/6/8 caddy. Gm also used them on 4 cylinder sunbirds with the turbo 4 motor.
Mine runs street duty, Powertour's, and is going into its third driving season on the car. It use's 12 amps and at 13.4 volts it will make 16 inches of vacuum "deadheaded". At Wot I field the Alt to incress the voltage to 16.4 and at that it makes 20 inch's dead headed! .
I bleed off pressure as mentioned in my first post and run it at 13" at 16.4 volts.
MY testing of a LT1 AIR pump dead headed was the same as the other reply stated...about 3.5 inches of vacuum.

My testing method was:
To dead headed, I used a rubber plug from the hardware store that fit the inlet of the pump (sucking side ) and drilled it with a 1/8 inch thru hole for the vacuum guage to plug into.

If Mr Gasket has pulled back the release of there Electric vacuum pump kit you could always go with the one from Stainless Steel Brakes Corp, Part # 28146. Ramchargers a board sponser sells for $239. We have moved a few of these thru our warehouse to guys in the detroit area.
The stainless pump looks the same as the Gm caddy unit.

 

Surfing, I found this vacuum pump that self regulates to 12". Has anyone tried it?

http://www.speeddemonmotorsports.com...acuumpump.html

 

Ah but the sb2.2 is probably one of the best heads out there for a single carb race engine like yours.
The again there are lots of choices.... best of luck either way you go. It's all fun.


That is very interesting Hawk! Always nice to find parts that you can pick up from the yard and on a budget. Thanks for the info.. I'll have to look into this a bit more.

-Mindgame

 

These guys do not sell a vaccum unit. I called them and they recommended the caddy pump.

 

Again let me say that the stock AIR pump has been tested and it won't pull anywhere near the amount of vacuum you guys are talking about.

The caddy pump has worked for guys like Madman, who is my source of info on this. I'm not saying it will work as good as a aftermarket BELT-driven pump, but as far as electric pumps go, it will work, maybe just be on the lower end of the range you guys are wanting.

 

Can someone give me a hint on treacking down this 4/6/8 vacuum pump.

Part number, year or model?

 

This is a great post. A couple of points I'd like to add from the
conversation on the previous page:

I read about the turning of the crank mains for reduction in rotating
mass. The trade off was higher RPM for crank strength, but it
allowed for quicker acceleration due to less inertia and more RPM
for extra HP.

I have actually considered turning my crank down and installing
oversized bearings when the time comes for an overhaul.

The discussion of low pressure in the crankcase is pretty wild too.
I'd have to lean on SStroker's theory as my research has stated
that the rings must be under load to avoid oscillating and breaking
apart.

The analogy was to use the human fist to strike a punching bag
with full force. The resistance (impact) of the hand contacting the
bag will save your arm from detaching itself. I guess throwing a
punch with all your might into thin air may illustrate the point in
this paragraph. You'd be lucky not to be in a cast, or dislocating
your shoulder after attempting such an experiment.

When applying those principals to rings and pistons, you can
visualize the rings and piston slamming back and forth a few hundred
times per second. Without loading the rings, or piston face with
some sort of resistance, the piston would make it's way off the
connecting rod and the rings would oscillate into distruction.

 

They changed that page... it used to have a pump on there, with specs and everything. I guess they don't sell it anymore.

I wonder how much of a PITA it would be to use a belt driven pump where the A/C used to sit in the stock acc. bracket. (supercharged guys will have a problem mounting it on the driver's side)

 

I checked my LT1 airpump against a vaccum gauge and it neted 2 psi.

I don't think it would create a vaccum at all on a crank case.


I did something unusual with my pcv problem because i was haveing a problem with blowing seals out. I took a brake booster check valve and put it inline with the PCV valve (you could blow air pass a stock brand new check valve, but you can't blow pass both).

I then ran the vaccum supply line to the PCV between the blower and throttle body. My throttle body is on the intake of the supercharger on my setup so it sees quite a bit of vaccum at an idle and probally sees a little vaccum at wide open

My setup is like this..
Air filter, throttle body, PCV source, roots type blower, lower intake,

With it like this i was blowing seals out.
Air filter, thottle body, roots type blower, lower intake, pcv valve


I guess you can say i used a roots blower for a vaccum pump

 

I went by a friend's house, he has a 8.97@150mph Renegade Mustang, and he runs the Moroso belt driven vacuum pump, it's plumbed into one valve cover. His is around 15 inches of vacuum. He says it's probably worth 20 hp and it helps with his rings.

I'll run the Caddy 4-6-8 pump and see what happens.

 

I've been following this thread, have lots of questions now.

1. So would a crankcase evac system (e.g., using the caddy pump) give any significant gains to a stock LT1 shortblock motor putting down about 385 to the wheels?

2. Would that system have any negative affects if that car were daily driven? I suppose a simple switch could be rigged to return back to an atmosphere-vented arrangement if necessary.

3. Any benefit to unplugging my A.I.R. fittings in the headers and using the AIR check valves plumbed to the valve covers to pull vacuum that way? I've seen it done on high dollar race cars, but is there any point to doing it on a street car/weekend warrior?

 

Can anyone give me more information in pointing me in the direction of how to get a "caddy 4/6/8" pump.

For example, what year /model.

 

First guy... I'm not sure 385rwhp level that I would bother. You have to seal off your pcv system too (I think).

Email Madman.