Thread:

Blower size.

Thought this would make a good non-political thing to talk about. We have blowers of all different sizes,14-71,12-71, 8-71, 6-71, 4-71 and the list can go on and on. Considering the power it take to turn one what would be the best sizes to use on different cubic inch and boost levels. I know how I have always done it but would like to hear the smart people talk. OK Bob. What you think.

Originally Posted by gn7

When was the last time you seen a 12-71? Wheres the 10-71. How can you expect me to take this thread serious?

Sorry Bob. I did not think you took anything serious except Ram Butt and Zombie.

Originally Posted by gn7

When was the last time you seen a 12-71? Wheres the 10-71. How can you expect me to take this thread serious?

10-71 I messed up on. The 12-71 was a BIG boat. Marine app. We can throw in the 16-92's and all of the bigger ones if you want. But all I really wanted to talk about was the ones we see often and are easily available. OK?

hell my 12-71 must be a rare one then.

lots of variables to consider. just a few here.... cubes, how well the engine takes the boost, how much boost, what type of fuel, compression etc. bigger weighs more, smaller builds more heat if you push it, how much power to run them also depends a lot on how hard they turn. a lot to consider when picking a blower.

for most gas deals being pushed to the edge, i say any negatives from going big, are way over come by how much less they have to work, and how much cooler they run. i would rather go up a little than down a little in size.

I don't claim to be an expert on the topic, but several years ago I was convinced by several people to go from a tunnel ram to a blower. What I have found is that after you put a blower on, you probably will not regret it or go back.

This is what I did. I have a Cole TR-4 with a 540 BBC, Dart pro 1 heads and a Blower Shop 14-71. I started out running AV gas at 5 or 6% under-driven and making about 9.5 lb. of boost. (static compression is 9.4 to 1) It was a good combination for me.

I see no reason a 14-71 would turn any harder than an 8 or 10-71 making the same boost, but it would provide a cooler intake charge. The difference in weight is maybe 10 lb. different, if that much. The 14-71 will just make more boost easier and when it's just cruising it turns no harder than a smaller blower.

I am now running the same combination with only the carburetors converted to E85 and making more power. I am reasonably comfortable with my tune up so it is now time to swap pulleys, which should make about 12 lb. boost. I am sure there is a lot more potential left, but I may be running as fast now as I am comfortable.

Depending on motor size, I believe the larger blower is the better way to go. For a 540, an 8-71 is on the lower level of being a good choice and if going with a larger blower, the 14-71 seems logical. It doesn't cost a great deal more than a 10 or 12-71 and offers more performance potential with no disadvantages. One exception would be you are limited on distributors. It must sit under the blower. I use a crank trigger along with a low profile crab type distributor.

Originally Posted by jimsplace

I don't claim to be an expert on the topic, but several years ago I was convinced by several people to go from a tunnel ram to a blower. What I have found is that after you put a blower on, you probably will not regret it or go back.

This is what I did. I have a Cole TR-4 with a 540 BBC, Dart pro 1 heads and a Blower Shop 14-71. I started out running AV gas at 5 or 6% under-driven and making about 9.5 lb. of boost. (static compression is 9.4 to 1) It was a good combination for me.

I see no reason a 14-71 would turn any harder than an 8 or 10-71 making the same boost, but it would provide a cooler intake charge. The difference in weight is maybe 10 lb. different, if that much. The 14-71 will just make more boost easier and when it's just cruising it turns no harder than a smaller blower.

I am now running the same combination with only the carburetors converted to E85 and making more power. I am reasonably comfortable with my tune up so it is now time to swap pulleys, which should make about 12 lb. boost. I am sure there is a lot more potential left, but I may be running as fast now as I am comfortable.

Depending on motor size, I believe the larger blower is the better way to go. For a 540, an 8-71 is on the lower level of being a good choice and if going with a larger blower, the 14-71 seems logical. It doesn't cost a great deal more than a 10 or 12-71 and offers more performance potential with no disadvantages. One exception would be you are limited on distributors. It must sit under the blower. I use a crank trigger along with a low profile crab type distributor.

exactly!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!! it cant be taking much more power to turn a 14 easy, VS an 8 hard. and the charge is going to be so much cooler. as far as cost, its nothing once you go above 8-71 . 10 to 14 is cheap. as far as the distributor goes, most will run a chiller, and that will give you the clearance you need. and if your awesome and go with a whipple deal, there are other options like you mentioned (crank trigger) & crab caps.

Originally Posted by MR. KILOWATT

I wanted to use a 6-71 on a 454. Lake boat not race. Are you saying that this is a bad choice?

I would not say it's a bad choice. First, the 454 is smaller than a 540 and therefore does not require as large of a blower to be effective. The larger the motor, the more air that is required as a starting point. I think there are many 6-71's on 454's with people enjoying the heck out of them. The 14-71 would provide more potential, but is probably going to cost more. Some 6-71's can be reworked to provide a decent boost on a 454 and if your compression is not too low, it will make more power, plus having the look of a blower motor.

There isn't necessarily a lot of difference between a race boat and a lake boat. It depends on what makes you happy. Mine is primarily a lake boat, it happens to be one of the quicker ones on the lake. I know there are others that are quicker, they just don't have as much sense as I do. (Some might say the same about me and they could be right.)

A guy in our boating group ran a 6-71 on a 565 chevy, spun it hard on c-16 and made 13lbs with it... Was in a 19 daytona jet and ran 9.20's @ 127 with it, had two 1050's on top of it.