Hi I'm Chuck Hanson, welcome to another Holley tech segment and today we're going to talk
about blowers.
That's right those creators of artificial atmosphere and horsepower, now today I've
got Shane Weckerly, the director of product management for Weiand blowers and well, he's
going to take us to school a little bit on these things.
Welcome Shane.
How are you doing Chuck?
Real good, now I've had blowers before and I know what a powerful addition they are,
but you know a lot goes in to I'm sure, you know deciding which one is right for your
particular application, take us through that.
That's certainly true Chuck.
You know there's a lot of things to consider when you're looking to put a blower on your
car.
You know one of the key things is what do you want to use your car for, is it a drag
racing car?
Is it a street cruiser?
Is it a fair grounds cruiser?
Do you just want to have a really good image and show off?
You know, what do you want to use the car for?
That's really the first consideration, you know once you've made that selection of what
you want to do with that car then you've got to decide you know, what kind of hood clearance
do you want?
Do you want the 671, 871 where you've got carbs and a scoop sticking out of the hood?
Or do you want a more conventional, lower profile that you may be able to sneak under
a 2 inch cal hood or something like that?
Those are kind of the 2 starting points for choosing a blower.
Well now I like the stealth look myself.
I believe in walking softly and carrying a big stick and for me I kind of like the blower
that stays under the hood.
Right, that's a good choice, the small blowers are real popular, they fit under a lot of
muscle car hoods with a small cal on them and you know they do give you that stealthy
look but the performance when you mash that peddle that they just rip down the road.
You know our smallest blowers come in a 142, 144 size up to a 252, 256 size.
That size relates to the size of the actual cubic inch of the blower, how much air it
puts out per revolution.
If it's a 144 it puts out 144 cubic inches of air for every revolution of the blower.
I see.
And that kind of gives you an idea of how big the blower is.
You know when your selecting that blower, like a small blower for your car, what your
going to see is that the small blowers have more lower RPM potential that the big blowers
do.
The big blower's going to make a lot more boost upstairs.
Sure.
They're going to be more efficient when you get into those higher RPM ranges, but the
little blowers are very efficient because they spin fast, the make boost right off of
idle, and they're really strong you know up into that 5-6 thousand RPM range.
Now is it possible to take a 200+ cubic inch small blower and put it on a smaller motor,
you know say a small block, 355 cubic inch small block and can you put a blower on it
that was intended originally for a big block application.
You can, you know you really want to match your supercharger to the size of the engine.
Good advice.
If you want a nice mild blower your looking at 5 or 6 PSI, you know you want to to stay
in the 142, 144 range for a small block, maybe the 177, 250 range for the big block.
So you mentioned 5 to 6 PSI of boost, you go over that, what kind of problems are you
going to encounter then?
Well your going to run into problems with getting good enough gas, your either going
to have to run race gas, your going to have to retard the timing a lot, you know your
going to have to lower the compression when you build the motor anyways.
Sure.
But unless your going to run an alcohol injection system or something along those lines your
going to have to stay under 5 to 6 PSI with a root style blower on the street.
Well know you mentioned you know the right engine combination, lowered compression ratio,
probably the right cam shaft design, what kind of cam shaft are we looking for?
Well you want to select your cam shaft accordingly, there again it's all about what your selection
criteria is going to be, are you going to race the car or are you going to have it as
a street car?
Your going to want to change your overlap depending on whether you know, it is going
to be a low RPM or your looking for that peak power.
Really the best advice I can say on choosing a cam shaft is you know, to call into the
experts and get a recommendation.
That's some good advice, always call in the experts if your in doubt, now another thing,
and I don't know if this is true or not, but a lot of guys say, man if your going to run
a blower you've got to have Ford's pistons, true?
It really depends, I highly recommend Ford's pistons but there are a lot of good crate
motor's out with a nice piston in them, you can get one with the 8 1/2 or 9:1 compression
ratio, you know that will make a good mild street blower engine, your not going to want
to run that too hard at the drag strip but for all around street car, I would recommend
that would be acceptable.
Great, great, now let's talk about this big boy over here, obviously a lot more capacity,
a lot more power potential.
Correct, you know the 671, 871 is really Weiand's traditionally staple in the blower line, you
know they've been around a long time, Weiand introduced it's first kit in like 1963 for
the Chrysler hemis and you know they've just been well accepted and widely popular for
years, you know they make great low end torque and horse power but they've just got a killer
top end on them that you just can't beat.
And they look really impressive, now looking at 2 what I notice, looking down through the
carb in-let here, I notice the smaller one has straight rotors, 2 lobes.
That's correct.
This one has a helix angle on the rotors and 3 lobes per rotor.
That's correct, we use a variety of different configurations in our blowers, all of our
small blowers have the 2 lobe configuration.
The 2 lobe configuration, number one is very good for producing a lot of low end boost
which is what you want on a small street blower.
They give up a little bit of high RPM efficiency and that's when you get into the 871's and
have the 3 lobe.
When you really want to race the motor and you want all that you can get out of the blower,
you know step up to a 3 lobe and that's going to move your RPM potential up in the RPM band.
Ok, now I've also heard people talk about teflon strips on the lobes of the rotors to
seal better the case, I noticed these don't have it.
That's correct and that's really just a an effect from deciding what you want to use
the application for.
Teflon strips, we use on some of our smaller street blowers to help increase that low RPM
potential, the 671 and 871 that Weiand produces do not have that.
You know we predominantly reserve that for race type applications on the 6 and 871's.
Is there sort of a generalization that you can say about, you know, choosing a small
one as apposed to choosing a big one, I know you mentioned, you know, what do you really
want to do with it?
Do you want the looks?
Do you want the stealth look?
Do you want more upper end performances?
There's sort of a generalized thing that we can share with everybody who is watching here
today to say, "Ok that's the one I need".
Yeah I think the big thing is really deciding what you want to do with the car, for hood
height and you know appearance.
Either blower will work in most applications.
If you don't want to see the carb sticking through the hood, you don't want that big
scoop, then I recommend you go with the smaller blower, especially for a street type application.
You know if your like me and you've got a car that you want to cruise the fair grounds
with and you want to show off and you want of make a lot of noise then I highly recommend
this because it's got a killer combination.
Well I'll tell you what, I've learned a lot here today, I've owned both types of blowers
and I can tell you, either one of them is a kick in the butt, but Shane, I thank you
for coming in today and taking us to school on this little bit, man you helped me make
my decision.
Good let's put one on that Chevelle.