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Old 03-10-2011, 07:34 PM
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sbc oiling system at 7500

What oiling system modifications are recomended for an engine that will see 7500 rpm. Solid lifter, 3" stroke, sequential injection, cop ignition. 1pc rms, for now I have a stock Vortec pan, would upgrade if there is a real need. I am considering an accusump, but is there a better alternative? Any merit in running a BBC pump with more teeth?

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Old 03-10-2011, 08:07 PM
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Quote:
Originally Posted by ap72
What oiling system modifications are recomended for an engine that will see 7500 rpm. Solid lifter, 3" stroke, sequential injection, cop ignition. 1pc rms, for now I have a stock Vortec pan, would upgrade if there is a real need. I am considering an accusump, but is there a better alternative? Any merit in running a BBC pump with more teeth?
Street, strip, round or road course?

The big issues with that many RPMs is oil supply as in more capacity and control of that capacity. If space prevales, a deep pan is the better solution to more capacity, if you can't go deep then a hammer head wide pan can be used. Both require trap doors and baffles to keep the oil flowing toward and trapped around the pick up. This is of the most importance with an engine that not only sees high revs but gets twisted through corners as well, and that could include the street if your an aggressive driver. The extra volume no matter how it's carried is both to insure the pump doesn't get up to or ahead of the supply and the volume is sufficient so that any given amount of oil has a few seconds to out-gas any bubbles before it goes back into the pump. The Accusump is a good back up should the pump be starved for a moment but isn't a substitue for good oil supply management.

Those RPMs are going to require a very good windage tray and a crank scraper. I prefer a full coverage windage tray, that's to say from the front main to the rear. I like louvers rather than screens but one or the other is better than none. The crank scraper can be built into the pan, or a fold on the windage tray, or a separate crank conformal piece fastened at the gasket rail. The point is to catch the flying oil and peel it off the crank and get it back into the sump.

If you're running roller rockers; the drain backs from the top end need to be protected with screens and magnets to prevent any roller bearing wreckage of a failed rocker from getting into the pan. Most high RPM situations, also, require that the rear drains be minimized in size to reduce the oil flowing onto the rear counterweights and rod throws. This will cause the valley to flood till the oil can drain down the timing case. The small returns at the rear will allow the valley to drain out after shutdown.

I'm not a big fan of roller thrust bearings for the cam gear, This is a small object failure point with no practical means of protecting the oil supply from it. However, I do like a brass washer between the gear and the block. At high RPM even a flat tappet cam jumps around a lot and will beat the crap out of the block with the softer gear, a thrust washer in here takes the beating instead of the block and blocks are expensive to replace. I also prefer to restrain a flat tappet cam with a roller tappet bumper if that type cam is a path you're considering, it does add to lifter and lobe life.

I like the big block pump, it provides more volume which can be used in a loose clearance high RPM engine. The favors I find it gives is a 12 tooth gear over the SBC's 7. The tooth count is further away from the natural cadence of the engine so your getting a 12/8 instead of a 7/8 beat frequency. This reduces pump chatter eliminating all the grooving and reshaping the exit cavity that's blocked by the large gear teeth passing over it. I prefer to modify the return from the pressure bypass valve so it vents back to the pan rather than back to the pump inlet side of the cover. This recirculation just heats the oil something fierce. The bypassing oil needs a little part fabricated that bolts the the pump cover to absorb the exit energy and direct the stream away from the crank nor directly into the pan, let if hit a sidewall or the underside of the windage tray first. The pick up needs to be securely fastened to the pump base both where it enters the inlet hole and by a brace, especially in a high RPM engine where vibrations are very strong and tend to shake the pickup tube apart if it isn't super secure. Given the cover bolts are holding several non indigenous parts to the pump body, they need their heads cross drilled and secured with twisted safety wire.

That should do you for regular vists over 7 grand.

Bogie

Last edited by oldbogie; 03-10-2011 at 08:20 PM.
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Old 03-10-2011, 08:18 PM
How fast is fast enough?
 
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Very thorough as always. I'll have to see what I can do about the pan, the rest shouldn't be a problem. Btw, this is a hot street engine, and yes solid flat tappet cam.
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