Blower Question Again
 

Whats Better If You Want To Go Mild 671 Ona 540 Or A 420 Megablower

Re: Blower Question Again
 

They are the same size. B & M's calls their 420 and everyone else calls their 671. I had a 420 on a 468 and made 625tq.

Harvey

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I would step out to the 8 71 you want spin it as fast and if you ever deside to step it up.my mild 494 ci made 762 on 93

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8-71 Blower Shop. :cool:

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mine are 540's w/10-71'S chilled. I would not go smaller than an 8-71.

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can i have that engine in your pic

good to have your posts back

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8-71s

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Run 8-71s. Replaced 250s with 8-71 on mild 509s, kept the same boost, and picked up 4mph and lots of torque.

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I would run an 871 also. On a 468 BBC with 8 PSI boost will make 800hp. Blower Shop or BDS are good choices.

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I'm runnin' a 454 streched to a 498 with a 420 @ 8pds boost and Merlin heads and my own grind cam at 625 lift and 8:1 static comp. Twin 750 holleys not blower referenced but with power valves. 91 oct fuel. Very happy with the setup in the 800hp range now. Never had a glich and runs like a bat outta hell. Idles all day without loading up, runs, races perfectly. It's a very reliable setup.

Re: Blower Question Again
 

Isnt the 420 rated as the same as a 8/71?????

nocigarette have you shoped the price diff???


I bet the GMC style is cheaper and theres alot more misc parts for them.might even find every thing used in good shape.I would defenly try to run a inner cooler if you could

Re: Blower Question Again
 

The 420 flows a few cfms less than a 6-71

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According to Holley Blower Tech the 420 blows higher than a 671 and very close to an 871. They say basically the same as an 871.

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Thats what I remember

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ck out

http://www.offshoreonly.com/classifi...1&cat=5&page=6

Re: Blower Question Again
 

6-71 = 6 x 71 ci in turn = 426 ci of air per revolution

420 B & M = 420 ci per revolution

8-71 = 8 x 71 ci in turn = 568 ci of air per revolution

The difference between a 6-71 and a 420 is that the 420 has straight cut two lobe rotors and the 6-71 has 3 lobe helical rotors.
So you could argue that the 420 could possibly move more air due to the missing lobe but is still closer to a 6-71 than an 8-71.
We run 420s on our Cig 509s and 8-71s on our 565 Cat motors both work well per application.

Re: Blower Question Again
 

huh? confused.thought the 6-71 was a model # meaning 6cyl 71 ci per cyl detroit diesel,8-71 meant 8 cyl 71 ci per cyl.how does that directly in the amount of air it pumps?.(by math)I know the rotor length is different, but I thought the 71 was cyl size not pumping capacity per rev. of blower?

Re: Blower Question Again
 

You are correct. The Detroit Diesel engine series are identified by the cylinder volume and number of cylinders. The blowers are different sizes for each engine.
Personally I'd go with the 8-71 if I were you. The baby blowers don't have a long life expectancy when compared to the DD blowers and they are just as expensive to rebuild/repair.
The Blower Shop or BDS can set you up with anything you need and are a wealth of knowledge. I think they both advertise here too.