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What gains can I expect...

 
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GrandSportC3
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Joined: 11 Jul 2003
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Location: Lakeland, FL
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1968 Chevrolet Corvette

PostPosted: Sun Jul 24, 2005 10:05 am    Post subject: What gains can I expect... Reply with quote

... from running without belt?

I have all electric accessories and I'm switching to the Crane Hi-6R which operates at a lower voltage than my current 6AL, so I should be ok just running off the batteries.
Does anyone here have first hand experience what difference not running a belt makes? All the big time racers run off the battery, so I assume that there's some kind of gain...
I only run one belt to the alternator right now..
Following major accessories are hooked up to the electrical system:

1) electric fan (15 amp draw)
2) electric water pump (5 amp draw)
3) electric fuel pump (5? amp draw)
4) ignition (50000 Volt HEI and Crane Hi-6R box

Any input is appreciated...
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clay
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1972 Chevrolet Nova

PostPosted: Sun Jul 24, 2005 12:17 pm    Post subject: Reply with quote

Personally I don't think you would gain much, but then again I don't know for sure. The only attempt I ever made at it was taking off the fan blade and it was a mess. I had let the car cool down a lot to prepare and had a bad string of events happen. First a car couldn't make it off the track after the burnout, so we had to sit there for several minutes. Then another burnout and I went straight to stage to try and hurry up the other guy. Then the car in the other lane thought he needed to do 75 dry hops for some reason. Mine was about 230* by now and I cut it off while fully staged. The other car finally overheated and puked (how ironic), I started up and of course went slower than I had all night. I never tried again after that and I guess what I'm trying to say is that it might not be worth the aggravation of making sure the battery is charged, carrying a generator, listening to the generator, wondering if it will crank, etc. Clay
Added - Looked at your E.T. after I posted this and had to add - I know why you are looking for the last little bit now. 11.05 is too close not to try something. Good luck on the 10's. Clay
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GrandSportC3
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Joined: 11 Jul 2003
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Location: Lakeland, FL
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1968 Chevrolet Corvette

PostPosted: Sun Jul 24, 2005 9:50 pm    Post subject: Reply with quote

clay wrote:
Personally I don't think you would gain much, but then again I don't know for sure. The only attempt I ever made at it was taking off the fan blade and it was a mess. I had let the car cool down a lot to prepare and had a bad string of events happen. First a car couldn't make it off the track after the burnout, so we had to sit there for several minutes. Then another burnout and I went straight to stage to try and hurry up the other guy. Then the car in the other lane thought he needed to do 75 dry hops for some reason. Mine was about 230* by now and I cut it off while fully staged. The other car finally overheated and puked (how ironic), I started up and of course went slower than I had all night. I never tried again after that and I guess what I'm trying to say is that it might not be worth the aggravation of making sure the battery is charged, carrying a generator, listening to the generator, wondering if it will crank, etc. Clay
Added - Looked at your E.T. after I posted this and had to add - I know why you are looking for the last little bit now. 11.05 is too close not to try something. Good luck on the 10's. Clay


I'm going to be in the 10's for sure.. When I ran 11.05, the hard top flew off and the tranny shifted at 5000 RPM (instead of the desired 6500 RPM)..
That was in 70 degree weather.. Now, I modified the tranny shift point etc. and have run 11.20 - 11.29 on a hot and humid Florida summer days..

http://www.corvetteforum.net/c3/grandsportc3/desoto1120.wmv

http://www.corvetteforum.net/c3/grandsportc3/desoto1129.wmv

On a 50 degree winter day (that's as cold as it gets here) I should be in the 10.70 - 10.80 range... However, my goal is to get into 10's on engine alone in summer and into the 10.60 range in winter... I have a few more mods coming. I should be able to knock 2 - 3 tenths of my ET to hit 10's in summer.. Once I'm in the mid 10's in winter, I'm going to add a 150 shot of spray to run 9's Very Happy Mr. Green Mr. Green Mr. Green
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96capriceMGR
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Joined: 23 Aug 2003
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1996 Chevrolet Caprice

PostPosted: Mon Jul 25, 2005 8:04 pm    Post subject: Reply with quote

With just an alternator spinning I don't see you gaining much, now if you were turning PS and or AC(even disengaged) then I could see it being worthwhile.
On cars like mine(mid 90s b-bodies) it is common practice for guys to pull the belt because our LT1 has a shaft driven waterpump, so we can pull the belt and stop the parasitic loses to the alt. which is minimal, the PS and the AC and it can result in as much as 2 tenths. Someone ran the math once and even at full load the alternator was only capable of a couple HP drag and the lower voltage applied to such important items as the ignition and fuel pump is worth that drag. With the alternator running all your accessories see more voltage than off the battery may not be a big deal for you but for fuel injected cars it becomes more important, bet they guys ith car like mine could pick up the 2 tenths more consistently if they found a way to only drive the alternator.
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GrandSportC3
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1968 Chevrolet Corvette

PostPosted: Mon Jul 25, 2005 10:42 pm    Post subject: Reply with quote

96capriceMGR wrote:
With just an alternator spinning I don't see you gaining much, now if you were turning PS and or AC(even disengaged) then I could see it being worthwhile.
On cars like mine(mid 90s b-bodies) it is common practice for guys to pull the belt because our LT1 has a shaft driven waterpump, so we can pull the belt and stop the parasitic loses to the alt. which is minimal, the PS and the AC and it can result in as much as 2 tenths. Someone ran the math once and even at full load the alternator was only capable of a couple HP drag and the lower voltage applied to such important items as the ignition and fuel pump is worth that drag. With the alternator running all your accessories see more voltage than off the battery may not be a big deal for you but for fuel injected cars it becomes more important, bet they guys ith car like mine could pick up the 2 tenths more consistently if they found a way to only drive the alternator.


With all the electrical accessories, I'm sure that some resistence builds up at the alternator (due to the magnetic field that increases the more draw is on the alternator)..

Anyway, I'll try it next time at the track and report back if it'll give me a better ET...
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mchat
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2003 Dodge Neon SRT-4

PostPosted: Tue Jul 26, 2005 3:32 pm    Post subject: Reply with quote

If you have a single wire type alternator, what about just wiring in a HD relay that you could control in the cockpit? Turn it off after the burn-out and then back on, on the return road. Idling back to the pits would probably recharge the system pretty well.

Without the generator field on, the turning resistance of the alternator would be greatly reduced, probably pulling less than 1/2 hp.

Also think about using a Deep Cycle battery like the Optima Yellow-Top.

BTW, there are formulas to convert volts/amp draw into Watts and then Watts into HP... that should give you an idea of what kind of hp the alternator is consuming.
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GrandSportC3
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1968 Chevrolet Corvette

PostPosted: Tue Jul 26, 2005 8:56 pm    Post subject: Reply with quote

mchat wrote:
If you have a single wire type alternator, what about just wiring in a HD relay that you could control in the cockpit? Turn it off after the burn-out and then back on, on the return road. Idling back to the pits would probably recharge the system pretty well.

Without the generator field on, the turning resistance of the alternator would be greatly reduced, probably pulling less than 1/2 hp.

Also think about using a Deep Cycle battery like the Optima Yellow-Top.

BTW, there are formulas to convert volts/amp draw into Watts and then Watts into HP... that should give you an idea of what kind of hp the alternator is consuming.

yup, that's exactly the information that I'm looking for..on how to calcuate it... All the fast race cars aren't using a alternator and there has to be a reason for that. They wouldn't do it if it wouldn't make a difference...
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87calais
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PostPosted: Wed Jul 27, 2005 8:16 am    Post subject: Reply with quote

Ok, so, I'm a dork and was kinda curious on this one myself, so I went internet hunting, now, We should all know off hand that volt x amp equals watts, so if you're spinning a hundred five amp alt to put out 13.5 volts, you're rocking with 1417.5 watts. Now, handy formula online says that watts X .00134 = horsepower.... so... that alt, would only be costing 1.89 hp .... plus whatever it takes to overcome the alternators friction, so merely unplugging even a big alternator won't do to much...... Hope it helps
Tim

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SMOKEmUP
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1979 Chevrolet Camaro

PostPosted: Wed Jul 27, 2005 9:00 am    Post subject: Reply with quote

87calais wrote:
Ok, so, I'm a dork and was kinda curious on this one myself, so I went internet hunting, now, We should all know off hand that volt x amp equals watts, so if you're spinning a hundred five amp alt to put out 13.5 volts, you're rocking with 1417.5 watts. Now, handy formula online says that watts X .00134 = horsepower.... so... that alt, would only be costing 1.89 hp .... plus whatever it takes to overcome the alternators friction, so merely unplugging even a big alternator won't do to much...... Hope it helps
Tim

That's also a good way to determine how much draw another accesory takes to power. You can use a motor to spin the accessory and record the voltage and current to get power, convert that to Watts, then HP and therefore figure out how much power it take to spin it.
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GrandSportC3
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Joined: 11 Jul 2003
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1968 Chevrolet Corvette

PostPosted: Thu Jul 28, 2005 1:07 pm    Post subject: Reply with quote

I would really accurately have to know how much draw is on the alteranator to calcuate the HP gains...
Anyway, I'll try it at the track and will see what's gonna happen...
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96capriceMGR
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1996 Chevrolet Caprice

PostPosted: Sat Jul 30, 2005 12:04 am    Post subject: Reply with quote

He used a 105 amp alternator at peak capacity for his example, that is a fairly common size on latemodel electically demanding cars these days, not much aftermarket even available over 200amp so even with friction at peak capacity you probably would never see a 5hp draw IF you have a BIG aftermarket alternator. IMO for the few HP it is better to keep all the electrical gadgets better fed.
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