Blower for 348 stroker?

[4d9r]

I was looking through a '59 Hot Rod mag and saw that they were running 6-71 blowers in A/G and got to wondering if I could run one on the street in the '31 Vicky I'm building. 348 stroked/bored to 408. Weekender not a daily driver. I was planning on running 6x2 or 4x2 and wondered how much more trouble it would be to run the 6-71 (love that whine!)
Thanks,
Terry

[rwagon57]

As with any blower engine, the best result is if the engine is purpose built as a blower engine. Forged pistons, 8:1 CR, etc.

The harder part will be finding the manifold. Blower Drive Service at one time produced a blower manifold for low performance heads (not 690 or 583), but I believe they have discontinued them. I was told a couple years ago that they still has some remaining stock, but now I don't know. Its probably worth a call to them.

[4d9r]

As with any blower engine, the best result is if the engine is purpose built as a blower engine. Forged pistons, 8:1 CR, etc.

The harder part will be finding the manifold. Blower Drive Service at one time produced a blower manifold for low performance heads (not 690 or 583), but I believe they have discontinued them. I was told a couple years ago that they still has some remaining stock, but now I don't know. Its probably worth a call to them.


They've got the manifold $1052 : 348-409 Chevy 671-871 manifold is 5 3/4 tall and includes factory style water outlet and backfire valve. Designed for small port heads. Water neck not included. Polish Option Part # C7081P
so.......what's the rest of the story?
Thanks.

[rwagon57]

1st a disclaimer - I do not have any hands on experience with building a blower engine. I am sharing general knowledge I have picked over the years from those that are more experienced and wiser in this area.

With a blower everything needs to be engineered to deal with the higher loads that result from putting more air and fuel into the engine. The good news is that all W- cranks are forged. If you are using a different crank it should be forged. Use premium rods and forged pistons designed to give about an 8:1 static compression ratio. Use roller rockers and match valve springs to the cam. Talk to your cam supplier about your specific application because blower engines like different cam profiles, centerlines, durations, and overlaps than normally aspirated engines. With an 8:1 CR and 5 to 6 pounds of boost (~10% underdriven) it will run on 91 octane. Make sure the cooling system is top notch, and upgrade everything behind the crank flange, because the engine will find every weak link.

I know there are others on this board that have specific expertise, hopefully they will weigh in here.

[blown55409]

I think you have a great idea 4d9r a 31 vicky with a blown W motor would be way cool.
I not an expert either but I have done a bit of research and I do run one.
Running a blower on the street is very forgiving there is so much torque you can run hiway gears and still blow the tires off when you want, you don't need a lot of cam but they tend to tame a big cam. A wide lope sep. like 114 will help. Call Crane Cams they will help you with your choice.
I looked for a long time for a blower intake and only saw one that was way over priced and it was for a 4-71. Your best option is the BDS intake I know it is over priced but if you have the motor everthing else should be standard fare.
With the light weight of the Vicky you should have no trouble running 8 lbs of boost on street gas, but you do want a blower case that has tight clearances not an old worn out one. With worn out clearences you would have to run the blower faster to get a given amount of boost which causes excess heat and heat is your enemy. Also you should run a boost retard adjustable 1-3 degrees per lbs of boost. Jet your carbs up 6% primary and 10% secondary should get you started.
A word of caution two things that have killed a blower the fastest are over tighting the blower case bolts and the drive belt. Case bolts to intake should be 15-18lbs max and drive belt should have 1 inch side play HOT.
very best regards
chip

[4d9r]

I think you have a great idea 4d9r a 31 vicky with a blown W motor would be way cool.
I not an expert either but I have done a bit of research and I do run one.
Running a blower on the street is very forgiving there is so much torque you can run hiway gears and still blow the tires off when you want, you don't need a lot of cam but they tend to tame a big cam. A wide lope sep. like 114 will help. Call Crane Cams they will help you with your choice.
I looked for a long time for a blower intake and only saw one that was way over priced and it was for a 4-71. Your best option is the BDS intake I know it is over priced but if you have the motor everthing else should be standard fare.
With the light weight of the Vicky you should have no trouble running 8 lbs of boost on street gas, but you do want a blower case that has tight clearances not an old worn out one. With worn out clearences you would have to run the blower faster to get a given amount of boost which causes excess heat and heat is your enemy. Also you should run a boost retard adjustable 1-3 degrees per lbs of boost. Jet your carbs up 6% primary and 10% secondary should get you started.
A word of caution two things that have killed a blower the fastest are over tighting the blower case bolts and the drive belt. Case bolts to intake should be 15-18lbs max and drive belt should have 1 inch side play HOT.
very best regards
chip

Hey Chip,
Thanks for weighing in with the positive remarks. Curt Harvey is building the motor this summer and I'm going to talk to him about building this blower motor as opposed to the naturally aspirated
motor we had planned. Also spoke to Craig @BDS who was positive and said curt was the man to do this right. Hard for me to get over the $1000+ for just the manifold but like you said, where else am I going to get one. I'll keep you posted on the direction this goes. Glad to hear your happy with yours!
Terry

[region rat]

BDS has a whole kit as does Dyers in Chicago Bob