Crankcase vacuum.
02-02-2008, 10:54 PM
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Crankcase vacuum. are there any circumstances in which having crankcase vacuum would not be good?
i run a 700hp dirt track car (406ci sbc on methanol) and am wondering if having one of those exhaust vacuum setups would be beneficial. no one i know has one or has ever run one, and i'm looking for every ounce of extra power.
i run a 700hp dirt track car (406ci sbc on methanol) and am wondering if having one of those exhaust vacuum setups would be beneficial. no one i know has one or has ever run one, and i'm looking for every ounce of extra power.
02-03-2008, 05:16 PM
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As stated above only too much can hurt and you won't make too much with one of those setups. They make very little vaccum. Would it be legal to run a vaccum pump on the car?
02-04-2008, 08:50 AM
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yeah it would be legal....but not ready to spend $500+ on the setup just yet unless yall think it would really be the way to go. i'll talk to my engine builder in the next few days and get his thoughts as well.
i run straight headers merging into twin 3 1/2" pipes that are 36" long each. the only downside is that we are required to run a muffler in each pipe. the muffler is an insert shown here - http://www.jegs.com/webapp/wcs/store...44688_-1_10265 .
with these mufflers, our power output goes down to around the 600rwhp mark (probably 40-50rwhp off of what free flowing tubes would be).
do yall think the back pressure would negate any vacuum effects and possible put pressure into the crankcase? or is that was the check valve in the evac kits prevents?
i run straight headers merging into twin 3 1/2" pipes that are 36" long each. the only downside is that we are required to run a muffler in each pipe. the muffler is an insert shown here - http://www.jegs.com/webapp/wcs/store...44688_-1_10265 .
with these mufflers, our power output goes down to around the 600rwhp mark (probably 40-50rwhp off of what free flowing tubes would be).
do yall think the back pressure would negate any vacuum effects and possible put pressure into the crankcase? or is that was the check valve in the evac kits prevents?
02-04-2008, 09:11 AM
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I've been told the header evac setups don't do much of anything when used with mufflers. I had them on my car years ago with mufflers and the car ran the same e.t. with and without them. I never tested it on the dyno. I've seen many motors pick up power on the dyno with a vaccum pump. Especially if the motor was built to run one and has low tension oil rings installled. If you go that direction you must install a vac. relief valve since the pump will be able to make enough vaccum to cause problems.
