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  #11  
Old 03-14-2016, 08:30 PM
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Dr Crankenstein Dr Crankenstein is offline
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Quote:
Originally Posted by kenny c View Post
Isn't Dr. Crankenstein an experienced supercharger man?
Yes and No.

Quite a few years back, we owned and ran a fuel funny car... BIG twin magnetos, dual plug heads, two pumps, 32 nozzles and 40+ lbs. boost.

That ^^^^ was a completely different animal and I have no experience with alcohol, except for the drinking variety...

I can appreciate the need for a hot ignition, however. With mechanical injection, the last thing you need is a weak or dead spark. (Think hydraulic lock and your crank "on the floor".)

sc5080, pick up an issue of Quick Times. Your local speed shop(s) should have it and it's free if they do. It's an Alberta publication, Don is a racer and the magazine is heavy on the classifieds.

http://www.quick-times.com/

.
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  #12  
Old 03-14-2016, 11:47 PM
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Bob - I've been looking but I'm a little afraid to buy used parts from someone I don't know - especially long distance . Good Vibrations had no magnetos in stock (new or used) when I spoke with them last week.

Annamel - your setup looks pretty cool. I expect, however, that you were running it on gas. Alcohol is an entirely different beast and needs a hotter, longer duration spark to fire properly.

Dr. Crankenstein - Thanks for the suggestion. I had forgotten about Don's magazine. I met him several years ago when I was racing at a National Open in Calgary. He was running a Cobra super gas car back then. And yeah, stock Chevy blocks are weak enough without adding misfire and backfire problems to the equation. It may look real cool but I really don't want to run over the crank (think Magic Muffler Fiat).
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  #13  
Old 03-15-2016, 09:02 PM
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I think you are over thinking it. The MSD 7AL will work fine for what you are doing as long as you are using the correct coil for the application. If you said you were running 15-18 psi and going to turn it 8K rpm then I would say go with the mag. You will want to spend time on indexing your plugs to the direction of the intake charge and tighten your gap up to get a good hard spark ball. Run a quality 8mm wire set as well. You won't "blow out" the spark with only 12 psi especially with alcohol. Mags help you by doing 2 things. 1 they run with very little or no power and 2 the faster you spin them the more energy they make. A regular coil set up starts to lose power when you get up into the 7K - 8K range as they just don't have time to populate the coil. Where you are probably not going to turn it over 6500 and are not running an insane number for boost your set up will be fine. Just my $.02

I used to run straight methanol in my WKA Karts so I'm familiar with the properties although they were not blown...
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  #14  
Old 03-15-2016, 10:49 PM
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Thanks jfg455. Your response is well thought out and overthinking things is something I am known to have done once or twice in my life .

If I do wind up going to the MSD I will be using their HVC II coil as it appears to be the highest output available at an advertised 2 amps. Plug gap would have to be closed up to .015 to .018 I think but that's the same gap range for a mag.

You may be right as to the rpm where my calculations would indicate just over 7000 at the finish line considering slippage at the converter and in the trans provided the motor makes the power I anticipate (approx 750). Static compression on this engine is 10.25:1. If the car will pull a 3.50 gear on a 29.5" tall tire I should see low to mid 8's at 160 - 165 mph. This should be feasible if the GMC 671 blower will make enough boost without heating the air to much. I am really trying to avoid the temptation to put my 871 on it.

I would pull about 72 - 7300 rpm with a normally asperated injected alcohol setup with a 451" Chrysler wedge at 13.5:1 compression running a 33" tire and 4.11 gears. That combination went 8.0's @ 168. It was when I put my 871 at 9% under on that engine at 11:1 static compression and saw 17 - 20 lbs boost that I ran into problems that may have been due to the 7al2 ignition.
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  #15  
Old 03-16-2016, 02:43 PM
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Mid 8's at 165 mph! That is gonna be moving on!
That would be like a what, 4.5 in the 1/8th? No 1/4 mile tracks around here, everybody races the 1/8th.
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  #16  
Old 03-16-2016, 05:08 PM
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Quote:
Originally Posted by sc5080 View Post
If I do wind up going to the MSD I will be using their HVC II coil as it appears to be the highest output available at an advertised 2 amps. Plug gap would have to be closed up to .015 to .018 I think but that's the same gap range for a mag.

You may be right as to the rpm where my calculations would indicate just over 7000 at the finish line considering slippage at the converter and in the trans provided the motor makes the power I anticipate (approx 750). Static compression on this engine is 10.25:1. If the car will pull a 3.50 gear on a 29.5" tall tire I should see low to mid 8's at 160 - 165 mph. This should be feasible if the GMC 671 blower will make enough boost without heating the air to much.
The alcohol will help keep the temps down but I think you will be seeing the 15-18psi down at the big end. Looking at your combo and rpm range I would now say you might be right at the limit of what the MSD will handle. You just might be better off jumping to the Mag and kill 2 birds so to speak. 1: eliminate spark issues by having just a bit too much of an ignition system and 2: it will be ready when you decide to dump the 871 on it and test the structural integrity of the block
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  #17  
Old 03-16-2016, 05:37 PM
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Quote:
Originally Posted by Bamamav View Post
Mid 8's at 165 mph! That is gonna be moving on!
That would be like a what, 4.5 in the 1/8th? No 1/4 mile tracks around here, everybody races the 1/8th.
Not quite that fast . It would work out to 5.20's to 5.30's at the 1/8. 5.0 works out to about a 7.90. 4.5 is a very low 7 in the quarter. Very quick figuring is 1/8 time X 1.58 = an approximate 1/4 time.
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  #18  
Old 03-16-2016, 05:46 PM
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Quote:
Originally Posted by jfg455 View Post
The alcohol will help keep the temps down but I think you will be seeing the 15-18psi down at the big end. Looking at your combo and rpm range I would now say you might be right at the limit of what the MSD will handle. You just might be better off jumping to the Mag and kill 2 birds so to speak. 1: eliminate spark issues by having just a bit too much of an ignition system and 2: it will be ready when you decide to dump the 871 on it and test the structural integrity of the block
Thanks jfg. That's pretty much the conclusion I have come to although several people are encouraging me to go with the MSD Grid system. Now all I have to do is find a reasonably priced mag from a reliable source.

I'm thinking the 871 will stay on the Chrysler engine. If i decide the small chevy isn't fast enough I can put that in and go run that 4.50 that Bamamav is talking about . That engine makes over 1200 hp on a mild tune up and about 1500 when its set on kill. Enough to keep me entertained anyway!
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  #19  
Old 04-29-2016, 12:20 AM
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Made a decision and bought a Mallory SuperMag III from Spud Miller at FIE. Nice folks and great to deal with.
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