Oil

[Bob Mustic]

I have a Stage II motor in my Kit Cobra and have a question about oil for anyone that can help.

I use a Weaver dry sump (3 stage) oil pump on my motor. The motor is normally aspirated and makes 473 HP with a 4 barrel carb.

I currently am using 10/30 Mobil 1 oil. The engine idles at 800 RPM with 65lbs of oil pressure. Runs 75psi at 2000 and around 100psi at 8,000 RPM (had someone else looking).

What is the general opinion on running 5/30 with the above? 0/30? Would it gain any horsepower? Remember I can't simply "Turn up the boost" to gain power. I have to tweek the motor in any way I can to maximize the power.

Also I'm planning on using the dry sump pump to pull a vacuum in the motor. Do I need to have any kind of relief valve or "break" in order for it not to pull too much vacuum and possibly damage seals or the silicone at each end of the intake manifold.

Any input would be greatly appreciated. Remember this car goes up against Big Block Fords at the Cobra meets and you guys don't want a FORD to beat a Stage II RIGHT?

Thanks,

Bob

 

[Bad as L]

First off, your oil pressure seems a bit high, you could be loosing a few HP right there. The current thinking in endurance racing (NASCAR) is to run the lighter 0 wt oils, there is HP to be found there also and it doesnt seem to bother longevity. I think they like to run the synthetic oil on the cool side too....around 170 deg.

IMO I wouldn't get to carried away with vaccum in a street driven engine. It will pull oil away from area's that you don't want it too, like valve guides and ring lands. They say that a well designed drag race dry sump will keep about a cup of oil in the engine. That aint enough for a street mill IMO. You loose to much cooling by not having the oil there. Valve springs come to mind.

And if you ever want to get that 6 holer out of there and put in a real engine. I got a 483 ci Shelby blocked FE sittin in my spare bedroom
A ford guy

 

[Bob Mustic]

Bad

Re the Ford motor. Why would I want to go slower?

Right now the cars going 10.8's without getting the launch perfected. Chuck L. thinks it will go 10.3's and I think 10.5's. I haven't run across a BB Ford at the Cobra meets that can beat those times and even if they could they'd need 200 addition cubic inches to do it. Not to mention having a boat anchor in the front of a 2300 lb car<G>

Seriously the Ford powered Cobra's are OK but I wanted something different. Having a normally aspirated 6 that goes into the 10's is just what I wanted it to do.

As far as the oil pressure goes if I go to the thinner oils the pressure will come back. The Weaver dry sump pump has an adjustment to raise or lower the pressure so I can tweek it lower when I get a handle on what oil I'm going to use.

Regarding pulling a vacuum in the system I wouldn't do that on the street just when we race it. I could use the extra 15-20 horsepower to battle all those Ford powered Cobras.

Regards and thanks,

Bob