MelloYellow

Saw someone local installing a high volume vacuum pump with a breather/catch can. They think by relieving the crankcase of pressurization they will increase the engine power of their LS1 20-50HP.

I have no experience with this.. They said some racecars use that setup. The expected gains sound a bit high. They were planning to test at the track but not on a dyno right away.

Anyone know what they are talking about/thinking re: the expected gains? Looks like a relatively inexpensive setup.

LS1derfull

MelloYellow, if the reason so many dyno graphs drop off suddenly above 6500rpm is because of excessive crankcase pressure build up and the guy using this scavange system plans on spinning higher than that , it is possible to gain most of his claim. I think this is extremely interesting and absolutely want to know how it turns out!

LS1derfull

Has anyone played with something like this?

Orange Krush

I have never done but have seen done and dynoed! It was the Segal brothers and they both use this on their 10.xx second Stangs.They are local guys but do race nationally in Mustang events! They had eighth inch holes I believe 4 of them drilled in the hose going to the pump and by taping 1 or more of these holes with duct tape they acheived a negative vacum number in the crankcase!On the dyno they saw as much as 22 more horsepower with their setup! I would never have believed if I had not seen it with my own eyes! <img src="graemlins/gr_hail.gif" border="0" alt="[hail]" />

MelloYellow

Wow! Wasn't expecting a positive response.. Hmm..

I don't think this guy spins his engine above 6500 tho. He has an A4 and his shift points are 6400 I believe.

The BeaSSt

iTrader: (1)

[quote]Originally posted by ChrisB:
<strong>You really saw that much rwhp? At what rpm?


Chris</strong><hr></blockquote>

We did not have access to a dyno immediately after the install but we did go to the track and that along with removing the power steering produced a 10.47 compared to a 10.61. Not a cheap mod either, pump, pulleys, baffles welded in the valve cover, catch can, custom bracket, custom mandrel for the crank pulley, AN fittings, hose, adj popoff valve, etc about $1200. Worth it to us though. We have since dynoed and saw a 17-20 gain on 3 pulls.

Dave
ARE/FASTECH 432
www.thebeasst.com

LS1derfull

Mighty mouse, your comments are wrong, its not the same thing. ALSO IF YOUR PAYING ATTENTION Ls1 block doesnt vent proerly, thats why GM redesigned crank case for proper venting. This pressure build up is equivalent to aerodynamic drag on exterior of car at hi speeds.Crankcase vacuum promotes oil control as far as splash control windage and ring sealing ability this is fact, and its worth power, how much with LS1 depends on how bad pressure builds in crankcase.
Oil drag on lower end can be compared to trying to run in 3feet of water(very innefficent)
I havent even brought up loss of power when oil gets in combustion from excess crankcase pressure causing detonation. YOu can add that power to what i have allready discussed.

Terry Burger

iTrader: (4)

If you run low tension oil rings, I think you'll see 10rwhp with it, otherwise almost nothing.

LS1derfull

LS1 and NORTHSTAR do have low radial tension rings, there also thinner than traditional chevy rings.

LS1derfull

Also comparing LT1 gains to LS1 is not valid, LT1 doesnt have trapped pressure pockets causing problem the way LS1 does. I do believe the right amount of vacuum would be important and too high would create wrist pin oiling problems possibly and maybe hurt piston underside cooling from lack of oil splash.

MelloYellow

Thx for the comments.

FWIW, I think they saw around 4" on the vacuum gauge today.

[ January 27, 2002: Message edited by: MelloYellow ]</p>

Visceral

iTrader: (1)

Hey there,

Jon (jmX) built one and had a vacuum guage attached to the crankcase on his 00' SS.

He saw 0 gain even when things were working rather well.

20-50 hp is not going ot happen. On LT1s, folks have seen 5-9 hp in some cases at very high rpm.

Chris

ChrisB

I saw 4rwhp at 6400 or so - and was still pulling 7" of vacuum (LT1)

He needs to watch out about pulling to much also if he is going with a serious setup - I wouldn't pull more than 14"

Chris

[ January 27, 2002: Message edited by: ChrisB ]</p>

1dirtyZ

iTrader: (1)

doesn't beaSSt have that set up??

The BeaSSt

iTrader: (1)

17-20 rwhp is a more realistic number. Don't pull more than 10-12 inches or you may experience oiling issues. Pics on our web site.

Dave
ARE/FASTECH 432
www.thebeasst.com

MIGHTYMOUSE

iTrader: (59)

i would think that excessive vacuum would be just as bad as blow by.. either way its more pressure keepign the pistons from moving where they want to move. i say 0 is the hero

ChrisB

You really saw that much rwhp? At what rpm?


Chris

ChrisB

[quote]Originally posted by MIGHTYMOUSE:
<strong>i would think that excessive vacuum would be just as bad as blow by.. either way its more pressure keepign the pistons from moving where they want to move. i say 0 is the hero</strong><hr></blockquote>

A vacuum is good - it allows for better ring seal and reduces oil consumption greatly.


Chris