It's funny. I don't think the 1954 SAE paper mentiond the little engine at all. http://wildaboutcarsonline.com/memb...s/9990410469032/1953_SAE_Paper_-_V8_Buick.pdf
Rusty makes a good point here, the 671 takes more to torque to make the same amount of boost. Actually when it comes to blowers what I remember from the early years ('50s and '60s) of huffing for fun and profit was that the 671 was popular on the track with the big inch motors and the 471 was more commonly seen on street driven vehicles. granted at this stage of life memory can be selective.
Here is a chart for a Weiand 6-71. It predicts boost vs drive ratio for various size engines. http://www.onallcylinders.com/wp-content/uploads/2013/02/Drive-Ratios1.jpg
Ok going by that chart of my math is correct and all things linear (of course I don't think they are) I'm looking at a little over 11 pounds of boost. My question is what is the compression ratio they are basing this off of?
Well I just found a calculator on performance trends website and it's saying a 35% underdriven 671 will still make 21 psi so that's not gonna work. I guess I'll start looking for either a 471 blower or a 401 nailhead.
I haven't built or finished a blower motor in a while (I have a big block that I have been helping/consulting on) but the most common rule of thumb is about 8:1 static compression for a blower motor or at least for a street blower motor. You say that you are looking at 11 psi of boost I am guessing according to the chart. What you need to realize is that if you boost below 10 psi you are in pretty good shape carbureted, once you hit 10 psi your fuel demands go up exponentially. It is the nature of the beast. The fuel demands go up enough that what we have done in the past with boosted motors both blown and turbocharged that produce more then 10 PSI is to use a boost sensitive switch and a separate tank with a nitrous nozzle and solenoid to supply fuel ( aside from the carbs) once we hit the 10 PSI mark. I am not in anyway trying to discourage you from huffing your motor I am afraid that with the older baby nail you are in for a lot of work to get it to a place where booting is a real possibility. Good for you for giving it a try.
Something with your calculations does not seem right. Check this out: http://www.blowerdriveservice.com/technical-charts.html
Something else to think about.....boost depends on what's been done to the blower, big companys will keep them loose so not to make dumb boost, set them up tight....and look out. we did a 383 sbc with an old diesel 6-71 that was converted by a guy that KNOWS blowers. 1:1 pulley, 18+ psi... 10% underdriven and it still pulled 16psi...on a dyno so not 'real life driving' but the charts are just charts based on the mfg's specs
Just thinking maybe the thing to do is go with the later 425 Nail 6-71 blown, so you have stronger parts and 8 bigger holes to take up the boost By having the larger engine you could play with pulleys and boost if you wanted to, and not be stuck with one combo like on the small engine Then save your little one for a un-blown deal and that way you can keep both of them alive
Actually one school of thought on boosting is that the more room you got the more mix you can stuff in it. I wouldn't mind huffing a 322 or a 364, both are good engines. I would not throw a 671 on the 322, its like using a 55 gallon drum for a fuel tank on a model T or a Sombrero on a Mouse.
Looks like the coupe may be sporting an old time v belt blower setup come the spring...watch this space. Going for a 4-71 on its 322.
The guy I got the 264 from is bitchin he wants the starter and exhaust manifolds off it because they weren't part of the deal so I'm gonna go drop the whole engine on his door step. I'm going to pick up a 401 with Trans this weekend with any luck.
Alright 91 that sounds like a great plan, now you can have lots of inch's for your boost and a 6 too Very Good !!!
Hi 91 When I was running my gasser at San Fernando drags in the 60's Tony Nancy had two different roadsters, one model A and a modified with a T body and then both had the blown Buick and I got to see them up close and always liked they way they looked Some engines just look right with a 6 on top like your Buick and a 392 Chrysler, but a sbc is too small and looks over whelmed by the 6 The box shaped covers just go hand in hand with that big blower, and there were a bunch of different ways to mount & drive them from front to top mounting and using chains - v belts and the toothed belts that worked out the best
I put a 471 on a 322 in my coupe. I think it looks about right. I have a 671 for a 425 that I have plans on putting in my roadster. Either way you can't go wrong.
Ain't nothing like the singing of a roots blower, that's what hot rodd,n is all about making a little noise
Not really sure right now. I was thinking about throwing it in a 36 ford truck we are building but my dad wasn't having it so I'm thinking I want to build a shoebox gasser.