considering 6-71 blower on 383 [Archive] - Chevy Nova Forum

: considering 6-71 blower on 383


SeventyNova
16th-March-2009, 11:27 PM
I have a 383 in my nova that I built two years ago. it has a scat bottom end kit with the 4340 crank, 6.0" H beam 4340 rods and SRP dished pistons that give me bang on 10:0:1 compression with the 62 cc heads I am currently using (vortecs that have been milled). Are the parts in this bottom end suitable for a blown motor? ARP studs are used on the bottom end and it is a 4 bolt block.

I am considering swapping to a set of AFR 210's with a 75 cc chamber to drop the compression down to about 8.8:1 and adding a 6/71 blower on top. However this would be my first experiance with a blower and I want to do it right. Does any one have any suggestions on good books to read on this or have any personal experiance on a similar build?

straightaxlenova
17th-March-2009, 12:43 AM
I'm using a Scat 4340 crank and rods on my blown alcohol 383 with a 6-71. I'm also using SRP domed pistons for 12:1 compression. I am currently limiting the boost to 11 psi, and have run a 9.05 @146 mph with this combination. No problems as of yet.
I intend on increasing the boost to around 20 psi, so I will switch to aluminum rods for that power level
If you run the AFR 210 heads with your 6-71, and run a good stout blower cam, you will have a killer setup. If you are running gasoline, you could easily get away with 10-12 psi boost, and still be very safe. I know of one site member here that runs an Eagle 4340 crank, and h beam rods, and runs 20 psi boost with a procharger.

SeventyNova
17th-March-2009, 01:24 PM
I'm using a Scat 4340 crank and rods on my blown alcohol 383 with a 6-71. I'm also using SRP domed pistons for 12:1 compression. I am currently limiting the boost to 11 psi, and have run a 9.05 @146 mph with this combination. No problems as of yet.
I intend on increasing the boost to around 20 psi, so I will switch to aluminum rods for that power level
If you run the AFR 210 heads with your 6-71, and run a good stout blower cam, you will have a killer setup. If you are running gasoline, you could easily get away with 10-12 psi boost, and still be very safe. I know of one site member here that runs an Eagle 4340 crank, and h beam rods, and runs 20 psi boost with a procharger.

Excellent, I would like to run gas as it will be a street strip combo. I would like the car to run mid to low 10's on a 275 drag radial, assuming I can get it to hook and not break stuff. I am at 3200' as well so a losing a bit of power.

Does anyone have any reccomendations on books that might be good on supercharging small blocks? Any heads better than the afr 210's for this appliation? The car has a 4.10 9" in the back and a beefed up turbo 350 with a 3600 stall that I would like to use.

D-Man
17th-March-2009, 01:42 PM
You should be fine with your bottom end for a street/strip application. The AFR 210 Eliminators are hard to beat.:yes: The only thing I would consider adding is a crank pulley support. Especially up in the thinner air, your gonna be driving the blower pretty hard and it can put a serious load on the snout of the crank.:yes: That's why is fairly common to see small block cranks with BBC snouts and double key-ways.
Try giving Craig @ BDS a call. He's a hell-of-a nice guy and can fill you in on ALL of the ins and outs. He also sells all of the hardware you'll need!!

Thumper71
17th-March-2009, 03:17 PM
Don't forget to step up your ignition box to a 6BTM if running MSD. Will let you advance the timing for out of the hole performance and then start pulling timing out as the boost comes in. I am running a 383 SBC with a Hampton 6-71 which is 3% underdriven producing 6 lbs of boost, 93 pump gas and it ran after only four runs of playing 11.80 in the 1/4. This was with no adjustments, rolled it off the trailer, lowered the pressure in the tires, and went to have some fun. There's a lot left in the combo, but have to build up slowly as money is tight right now. I'm having a lot of fun with it right now and everywhere I go people love the blower coming over the fenders. I love it too!!:D

shawn63
17th-March-2009, 09:01 PM
Heres's a good book on the subject.

http://www.amazon.com/Street-Supercharging-Install-Blowers-S/dp/1884089291

nova656567
17th-March-2009, 11:38 PM
If you are going to be spinning the blower, you'll want to cut in a second 1/4" keyway as the factory half moon key won't hold up.

SeventyNova
18th-March-2009, 12:24 AM
If you are going to be spinning the blower, you'll want to cut in a second 1/4" keyway as the factory half moon key won't hold up.

Do I need to pull the crank to cut the second keyway in? I am thinking yes but not sure.

straightaxlenova
18th-March-2009, 12:31 AM
The crankshaft is going to need to be removed to get the keyway cut. The easiest way to do it is by turning the engine upside down on the engine stand, and push the pistons down in the bores.

nova656567
18th-March-2009, 08:11 AM
Yes you will need to remove the crankshaft. It's a good idea to have your crank hub when you have the crankshaft keyway cut. That way there are fewer opportunities for mistakes.