Blower Help Please....

[McDenny]

Hey all,
As I continue to "collect" parts for my bucket, I was planning on running a blower. I came across one today, a 4-71. I am a diesel mechanic by trade and have some experience with Detroit Diesels, changed out alot of 6-71 and 8-71, both turbo and non turbo.

I am unsure whether a 4-71 is going to be big enough, I see alot of 6-71 on both small blocks and big blocks, not to much experience with 4-71. I am going to run a big block Chevy 454 bored 30

Anyone running a 4-71?

Thanks,
Dennis

 

[regger]

In my opinion,a 4-71 is too small for your 454 engine. I have a 6-71 on my small block 39 chevy,and have a 4-71 on the small block in my 24 T(under construction).I dont beleive anyone makes a manifold for a 4-71 big block.You would have to use a 6-71 manifold and an adapter plate..

 

[RPM]

Being a diesel man you know that a 6-71 is 6 cly at 71 cubic inches each. So it that is 426 cubic inches. So the blower works good on a 426 cubic inch motor. For the street it will work fine on your 454, the 4-71 is really small for a big block. The 6-71 I have on my 355 will make 10-12 lbs of boost. The desk top dynos say 10 lbs of boost will make 2hp per cubic inch.

 

[McDenny]

Hey Ron,
Yea, kinda figured it may be too small. I am "assuming" it is off a "71" series. Detroit also made a "92" series, turbo and non turbo. The pistons height was actually different from turbo to non turbo engines,found that out the hard way :-(

 

[McDenny]

Hey tdreamer,
I have found a manifold, "custom made", but I have not purchased anything yet, was really hoping for a 6-71, so I will keep my eyes open. The 4-71 kinda just fell in my lap, it is right off a Detroit, so it needs to be redone, the guy just told me to make him a offer, he doesnt need it.

 

[RPM]

I just bought a Weiand kit for mine. It was fast and easy, and everything just fit right. The time you get a blower, then rebuild it and get the drives, and end plates, the belt the adjusters and all the small stuff. It just made sense to buy a kit. If you buy a manifold make sure you get one that will take a thermostat. Some of the race manifolds won't.

 

[McDenny]

Where did you buy it Ron?

 

[Golly]

You can buy a little adapter to put a thermostat in line, eg: in the radiator hose. If the race manifold is the right price grab it.!

 

[RPM]

Where did you buy it Ron?

I got mine through a good friend that works for Advance Auto.

 

[McDenny]

I got mine through a good friend that works for Advance Auto.

Like the franchise "advance auto" ? Didn't know they carried that kind of stuff.....

 

[RPM]

Like the franchise "advance auto" ? Didn't know they carried that kind of stuff.....

Yes they had it at the warehouse, called him one morning and they delivered it later that day. Summitt or Jegs will have it also.

 

[Screaming Metal]

Hey all,
As I continue to "collect" parts for my bucket, I was planning on running a blower. I came across one today, a 4-71. I am a diesel mechanic by trade and have some experience with Detroit Diesels, changed out alot of 6-71 and 8-71, both turbo and non turbo.

I am unsure whether a 4-71 is going to be big enough, I see alot of 6-71 on both small blocks and big blocks, not to much experience with 4-71. I am going to run a big block Chevy 454 bored 30

Anyone running a 4-71?

Thanks,
Dennis

Well, as you were told, its a bit on the small side. Not to say it wouldn't work, but you'd have to clearance it 'loose' and spin the hell outta it! Then, theres the Manifold and such.
Most folks running Big Blocks run either 6-71's or 8-71's. The 8-71's you can set them up middle-of-the-road clearance wise, because the rotors have more surface area, you don't have to spin them as fast, and it doesn't heat up the intake charge, making it more dense, yada, yada, yada.
Hang onto the 4-71 for a smallblock.
OR If you find someone whose gonna 'blow' a 6 cyl. or a little 4 cyl., its perfect. It often pays to hang onto something such as these.....never know when you might need it!
I had one on my Big Inch Six, I was running about 15% over, and it sounded like a turbo! Ran great and worked great. I ran a temp. check on my front bearings since my front endplate seemed to get a little too warm for my likes, I changed it out for a 6-71 and dropped down to 1:1 on the drive.

 

[23dragster]

I'm not an expert by any means on blowers; but I've run an 871 on a SBC for a while... It seems than a 471 would be a bit small for a BBC 454 as 471 cci of air moved would barely offset breathing on your motor. A 671 would seem better. I do know though, that an 871 even geared 31drive-42driven is too much for street use on a SBC around town. (Pulls front-end on regular basis and gets 6mpg). At least on my poor little motor.