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 mactaylor
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| posted on January 31st, 2008 at 07:51 PM |
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vacuum pump tech
any body running a vac pump? we used to in our speedway car and made good gains!
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dangerous
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| posted on January 31st, 2008 at 08:17 PM |
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Rodney does. His came from $hawn Geer$
the yanks claim 20 hp.(probably 10 in Australia)
Even 10 would be worth the money spent.
...although you can spend couple of grand pretty quickly depending on whose you buy,
and what you spend on braided hoses and catch cans,
or how much stuff you want to make and experiment with.
| Quote: | Originally
posted by westi
That's mad Alan.
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mactaylor
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| posted on February 1st, 2008 at 11:52 AM |
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I thinkl a gemini diesel had a pretty good pump on them, any other cars you know of?
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greedy53
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| posted on February 1st, 2008 at 12:21 PM |
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early commadors
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Judsons4eva
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| posted on February 1st, 2008 at 01:06 PM |
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Vacuum pumps on diesels are for a different purpose. As many diesels don't pull any vacuum from the intake they require a vacuum pump to operate the
brake booster. The vacuum pumps used on drag cars supposedly are meant to give a power boost by creating a vacuum in the crankcase and relieving
blowby pressure.
While the proponents of vacuum pumps claim HP increases but I seriously doubt 10 to 20hp increase (if any) - Frankly I wouldn't waste my money. They
were original put on drag cars that had large amounts of blowby out of ultra HP engines. The claims somewhat defy the laws of physics as to create the
vaumm you need to put energy into driving the vacuum pump so how can you get more power out than you put in.
Ken
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westi
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what the
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| posted on February 4th, 2008 at 10:35 PM |
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18 bhp on a fontana.also picked up a bit up a bit in mid range.
well worth the money if you are chasing an edge.
every engine is different so gains will always vary,but you can always play with pulley ratio's.
me personally,i have a million other things i can grap power from before i go down that road.i already have a full engine bay and don't need anymre
headaches.
down sharon.
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Judsons4eva
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| posted on February 4th, 2008 at 10:46 PM |
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18 hp in how much? can you explain why there is a hp increase?
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modulus
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| posted on February 5th, 2008 at 10:35 AM |
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| Quote: | Originally
posted by Judsons4eva
The claims somewhat defy the laws of physics as to create the vaumm you need to put energy into driving the vacuum pump so how can you get more power
out than you put in.
Ken
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Not quite. Superchargers, for example.
I think the 10-20 hp gains are probably on 6000 hp top-fuel engines (or, as dangerous pointed out, 3000 hp on an Australian dyno). That sort of gain
*might* be possible by the simple reduction of pressure on the underside of the pistons, 'though I haven't done the math.
hth
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dangerous
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| posted on February 5th, 2008 at 07:04 PM |
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I think the reduction of
windage,
and
Pressure,
allows the components to rotate and reciprocate easier.
A dry sump pump with a large scavenge stage/stages,
can do the same.
It seems that vacuum creation does produce more power,
but the gains are actual,
not imaginary like with criogenics and coatings....
| Quote: | Originally
posted by westi
That's mad Alan.
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Judsons4eva
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| posted on February 5th, 2008 at 07:52 PM |
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Ok physics can explain superchargers. Forcing air through a restricted intake system gets more air in the cylinder and the engine behaves as if it is
a bigger displacement.
Vacuum in the crankcase makes it easier for the pistion to go down (in on a flat 4) but conversely makes it harder for the piston to go up ( out on a
flat 4) so the net gain is zero. The only reason I can see is a greater pressure diffential accross the piston rings - so the rings seal better with
less blowby - but 30 hp in 3000hp as a ratio is not worth worrying about on a 200hp engine and the loss with belt friction etc will probably offset
any gains.
It does have the effect of lower oil pressure and that may give some gains
The only reference to vacuum pump gains on the web is from those selling them - there is nothing in the technical literature from the SAE etc.
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dangerous
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| posted on February 6th, 2008 at 06:14 AM |
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| Quote: | Originally
posted by Judsons4eva
The only reference to vacuum pump gains on the web is from those selling them - there is nothing in the technical literature from the SAE etc.
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I feel the same about cryogenics.
I think that there is a gain from vacuum pumps by the evidence I have seen and heard about from parties that do not sell them.
I think the key is not the vacuum so much as the "lack of pressure".
Perhaps it is purely due to better ring seal alone,
although you could argue ,I suppose, that if there was no problem there to begin with,
it would not be needed, or have less return of lost power.
Even sanctioning bodies feel it is an advantage,
and some classes have banned them.
I know a fellow with a moden engine dyno,
so will ask him if he has found particular number for the gain.
| Quote: | Originally
posted by westi
That's mad Alan.
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VWCOOL
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| posted on February 6th, 2008 at 07:50 AM |
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yeas a bloke I know fitted one to a Holden V8 years ago and there were gains in engine dyno power and times at the strip.Not sure how much - but it
was the basis of an article in Street Machine; I think it was a Holden 2.8-litre 'Blue' six (VH series) exhaust pump
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mactaylor
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| posted on February 6th, 2008 at 02:19 PM |
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gains are made not from the vacuum itself butyou can run lower tension rings and that there is less oil in suspention floating around for the crank to
run into. ang a lovely by product is that you get almost zero oil leaks!!!!
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Judsons4eva
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| posted on February 7th, 2008 at 08:34 AM |
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The only thing that can explain a slight power increase (20hp in 3000hp!) is the advantage of lower tension rings and the greater pressure
differential across the ring pack giving better ring sealing and less blowby. You are right about the oil leaks too as the first use of them was to
stop rocker cover and sump gaskets blowing out on nitro cars!
On most of the VW engines we drive I can see no advantage and a lot more hassle cluttering up the engine bay, with another drive belt.
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mactaylor
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| posted on February 7th, 2008 at 07:15 PM |
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yes but we arnt talking about a 1600 dp!!!!!!!
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Judsons4eva
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| posted on February 7th, 2008 at 07:24 PM |
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20 hp in 3000Hp is 0.6% so even on a 300hp super hot VW engine this is only 2hp and I guarantee the losses in the belt drive of the vacuum pump will
probably exceed 2 hp - so the net gain is Zero - so forget it!
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dangerous
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| posted on February 8th, 2008 at 06:16 AM |
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The gains are outright.
Net, not grosse.
The gains, wether 10, 20 or 30hp, are seen on engines from small to big, and not just 1000hp prostock V8s.
The fontana above that Westi mentioned was probably a 250 to 300hp inline 4 cylinder that is used for speedway.
The figure I was told for a V8 speedway engine was 20hp on a 700 hp 370 ci engine.
If the gains on a volksy were 10hp,
net
I think it may be worth chasing if you have exhausted all other avenues.
In my case I think I would go for a big dry sump pump to get some gains and improve the oil system at the same time.
Most engine builders and dyno operators in the racing world claim just going to a basic drysump system
reduces windage enough to show a net gain in power and torque despite the extra power needed to run them.
| Quote: | Originally
posted by westi
That's mad Alan.
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Judsons4eva
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| posted on February 8th, 2008 at 08:31 AM |
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I guess we'll have to agree to disagree - just can't see anyway a 5% gain in power can be had by having a vacuum pump attached to the sump. If it
helps you go faster then good luck - I'll be proven wrong.
Ken
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dangerous
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| posted on February 8th, 2008 at 03:22 PM |
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| Quote: | Originally
posted by Judsons4eva
I guess we'll have to agree to disagree - just can't see anyway a 5% gain in power can be had by having a vacuum pump attached to the sump. If it
helps you go faster then good luck - I'll be proven wrong.
Ken
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I would not say I disagree with your reasoning Ken,
but would like to try something like this, since reducing windage may be worthwhile in MY understanding of the way things are.
It may prove to be of little value, but I WILL know for sure,
not just think it might.
| Quote: | Originally
posted by westi
That's mad Alan.
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