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Bonneville Salt Flats Discussion => Build Diaries => Topic started by: wickedwagens on June 27, 2012, 12:14:36 AM



Title: Blown VW 36hp project
Post by: wickedwagens on June 27, 2012, 12:14:36 AM
Being a "VW Guy" and falling in love with land speed racing I decided to build a car to run in the 36hp Challenge and get my feet wet racing.  I am building a 68' VW Beetle with a 1500cc 36hp based engine.  Feeding this will be a GMC 3-71.  This will put me in the K36 vintage supercharged category.  Any Ideas will be greatly appreciated.
We started with this.
(http://i149.photobucket.com/albums/s65/wickedwagens/IMG_2433.jpg)
took it apart, cleaned, and rebuilt the blower.
(http://i149.photobucket.com/albums/s65/wickedwagens/0107121700.jpg)
Here is what we are working with.
(http://i149.photobucket.com/albums/s65/wickedwagens/0225121211a.jpg)


Title: Re: Blown VW 36hp project
Post by: DND on June 27, 2012, 01:38:14 AM
Hi Wicked

Since it looks like you are just getting started, could you use a smaller blower that would take less HP to run.

Just a thought'

Don


Title: Re: Blown VW 36hp project
Post by: Rex Schimmer on June 27, 2012, 02:15:08 PM
That blower is bigger than your engine!!! If you run it in a bug where the heck are you going to mount it and how the heck are you going to drive it?? Looking at the belt pulleys that you had it looks like a 4 or 5 to 1 underdrive ratio??? I agree with Don you might want to start with a smaller blower.

Keep it coming as what you are doing is really interesting and you will get plenty of "kibitzing" advice from us in the peanut gallery!!

Rex


Title: Re: Blown VW 36hp project
Post by: panic on June 27, 2012, 04:10:48 PM
X3 - even if you need that much CFM, the 3-71 has a higher parasitic load than (example) an Eaton M62, much heavier, higher discharge temperature, physically larger package. The M62 is pretty cheap, used from GM 3800 V6 on eBay.


Title: Re: Blown VW 36hp project
Post by: manta22 on June 27, 2012, 05:15:19 PM
More from the peanut gallery--

Sell the 3-71 and use that money to buy an Eaton as Panic suggested. It may not impress onlookers at car shows as much but you'll go faster!

Regards, Neil  Tucson, AZ


Title: Re: Blown VW 36hp project
Post by: wickedwagens on June 27, 2012, 06:29:32 PM
What would be a good supercharger that is pre 1965 and will put out +20 psi?  I looked at some other early superchargers and they are low pressure superchargers. 

Dick Landy has a kit for the later model VW's that uses a 4-71 and they work out alright.


Title: Re: Blown VW 36hp project
Post by: redhotracing on June 27, 2012, 06:56:47 PM
Can you run a turbo in that class? Blow through an A2W intercooler into a carb box?
It would definitely kill the problem of parasitic loss, and with that motor you could
use a small, self contained unit without having to mess with oil lines or external
wastegates.

If not, I'll agree with the other guys- an Eaton or other S/C with a smaller ratio;
you may gain HP with the 3-71, but you're losing a large amount in driving it. A
more efficient unit won't look as cool, but going faster is cool, too  :cheers:


Title: Re: Blown VW 36hp project
Post by: wickedwagens on June 27, 2012, 11:06:28 PM
No turbos allowed in the class.  Believe me, that it the way I would rather go.  We didn't like not being able to change pulleys so we took a small block chevy blower crank hub and adapted it to fit the vw crank.
(http://i149.photobucket.com/albums/s65/wickedwagens/0610121727.jpg)
Now we can swap pulleys around easier.
(http://i149.photobucket.com/albums/s65/wickedwagens/0610121443.jpg)
The plan is to run a shaft back over the transaxle and set the blower on the back side of the fan shroud.
(http://i149.photobucket.com/albums/s65/wickedwagens/0107121605.jpg)


Title: Re: Blown VW 36hp project
Post by: El Wayno on June 28, 2012, 01:02:05 AM
I think some early Shelby mustangs came with Paxton Centrifugal superchargers. Not sure on the year but should be close. Less parasitic loss in the centrifugal ones, built more similar to a turbo. The one you got looks awsome though. :cheers:


Title: Re: Blown VW 36hp project
Post by: Rex Schimmer on June 28, 2012, 10:54:32 AM
Can't wait to see how you bolt all of this together!

Rex


Title: Re: Blown VW 36hp project
Post by: DND on June 28, 2012, 11:14:54 AM
Hi Wicked

How much power do you plan on making with your blown V Dub, as talked about a vane blower might get you more bolt on power and that is a good thing.

These rotor types of blowers take a bunch of power to turn them, and with small cube's you do not wan't to give that away that is why bolt on power is something you should look at very close.

Don


Title: Re: Blown VW 36hp project
Post by: wickedwagens on June 28, 2012, 06:23:40 PM
I was under the impression that most of these vane style superchargers are not up to the task of high boost applications.  Which superchargers could be used in my application?  Pre 1965 and +20 psi boost??

Thanks,


Title: Re: Blown VW 36hp project
Post by: redhotracing on June 28, 2012, 06:57:37 PM
You say pre-1965, and no turbos; is the rule specifically against turbos,
post-1965 or both? If it's only pre-'65, an old turbo could surely be pulled
from the nautical or aviation industry. If not, I'd agree that a centrifugal
would be a better choice... Even if it can't make 20+psi, the difference in
parasitic loss may make up for that, plus add the benefits of reduced heat
soak and allowing use of a good A2W intercooler.


Title: Re: Blown VW 36hp project
Post by: saltwheels262 on June 28, 2012, 07:07:11 PM
I would tend to listen to the guys--

been there, done that and have loads of experience.


Title: Re: Blown VW 36hp project
Post by: manta22 on June 28, 2012, 07:44:47 PM
The Corvair Spyder ran a TRW turbo before '65.


Title: Re: Blown VW 36hp project
Post by: wickedwagens on June 28, 2012, 09:13:05 PM
Correct, NO turbos allowed even pre 1965.  A turbo puts the car in the Unlimited class.  I gave Tom Bruch an idea that helped him last year bump the record from 106 to 126 in that class.  If this engine will hold together and does ok a turbo will go on it and run again later, but for now I am sticking vintage supercharged and need about 20 lbs of boost to hit my goal.