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Which spercharger?

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#21 ·
Poster Child said:
How many cubes
how much boost
cam/head/exhaust efficiencies

All the above will determine how much air you can pack in a cylinder given a specific blower.
Each blower has a rating of X cfm per rotation. But each one has a max rpm too.
In the examples you've given, they're all roots type.
In my opinion, overdriving a roots by more than 15% is too much on a boat and creates too much heat, therefore adverse effects.

DAVE
Click to expand...

With that being said (again) With a 502, I would go with an 871 and that will give you enough room to do what you want to now and leave some room for probable upgrades later.

DAVE
 
#22 ·
Read the litterature on the Holley website. Especially the installation instructions, and all the extra PDf's that are out there. There a lot of good info on that site, but you have to dig for it.

Acording to the Holley site...

The reason Mercruiser puts 177 blowers on there is because the smaller SC's will produce better bottom and mid range power, and loose little top end power compared to the larger SC's.
Most people (not all) who go with a 671 on thier '70 Chevelle w/ 350 is because it looks more impressive than a 177 SC.
Larger SC's will produce better top end power, and you are right. Larger SC's will be underdriven to produce 3 lbs. of boost where the smaller 177's will be overdriven, therefore producing more heat than the larger 671's, 871, or especially 1471's.
 
Discussion starter · #23 ·
PC, would the 871 be a bit large for a basic stock 502? I mean is there such a thing as too much supercharger for a application?
I do not really want to turn the engine over 52-5500 rpms.
I really do not know much about the aftermarket superchargers and that is why all the ?s. Thanks Dwight
 
#24 ·
Yes, for a bone stock Merc 502 a 671 would be the better choice.
The point is, and be honest, are you gonna stay bone stock?

All my opinions listed are based on staying with a roots blower. If you want to know my entire opinion, a roots blower should be your last choice.

DAVE
 
#26 ·
Well......without turning this into a supercharger debate how about we talk good points/bad points.

Ok, so, I think that most everyone agrees there's hardly anything more beautiful than a big *** roots blower sticking out of a hood or hatch all polished and shiny.

Drawback: 1930's technology, 50-55% adiabatic efficency.

Whipple: Looks great, gobbs of power, great tech support.

Drawback: a little on the pricey side, availability these days is questionable, around 60-65% adiabatic efficency. Torque curve is flat so it's hard to "baby" it and that's why you hear alot of guys talk about it being hard on the drive and breaking them.

ProCharger: Looks good, progressive torque curve, makes lots of power. It is possible to be close to 75% adiabatic efficency. Can run more boost on same engine than above systems. Dollar for dollar you can make more power with a ProCharger.

Drawback: Poor tech support. You must have mechanical ability to install yourself. Fuel injection has limited power options because of pump pressures needed and fuel injector flows. For carb'd systems you really need a good carb guy to modify your carbs.

Now, to answer your question directly; I'm on my 3rd ProCharger motor. Started with a 600hp, then went to 900hp then went 1200hp.
Out of the 3 only the 900hp was a basic direct bolt on. Even then I had to make my own intercooler bracket. And NO! none of them blew up or ever had any damage. All 3 motors are still running. (the 1st nat.asp. now)

Again the reason being, dollar for dollar it was cheaper, for me anyway.

DAVE
 
Discussion starter · #27 ·
Thanks I appreciate the insight. One thing I see as a plus with the roots engine combo is that there are many people that have done them. I know of several myself. I do know a couple of procharger people but, not many.
I guess my point is it would be easier to learn on the roots due to the exposure. I think I would love the procharger but as far as tuning help and such I think it would be much harder. Dwight
 
#30 ·
Dwight said:
That is true. I know I could get to what I want NA but I was thinking 600-650 hp would be easier with a supercharger. What did your 600hp system consist of?
Click to expand...
Lets just head to Johnsons Speed Shop after work and get that huffer ordered. I will tell Steve and Greg there that we are on our way with cash in hand. :shocked:
 
#31 ·
Dwight - kinda sugs getting mentally beat up huh ? Take a little time out.

People are giving you suggestions, just remember that.

There is always more than one way to skin a cat. Did I say that? I like cats. :bigsmile:
 
#32 ·
Dwight,

It depends on how much power you're trying to make. With a 502, and a good 250 (like a Blower Shop unit) you can make 700 HP with a single King Demon or Dominator pretty easily. Unless you're trying to run a lot of boost you're going to be happier with a smaller blower since it will accelerate much faster. The difference in heating is going to be very minimal. The only down side to the smaller blowers is that they don't look as impressive!
 
#33 ·
dominator scott said:
Lets just head to Johnsons Speed Shop after work and get that huffer ordered. I will tell Steve and Greg there that we are on our way with cash in hand. :shocked:
Click to expand...
Can I come ? Can I come ?

I'm drooling over here !

<a href='http://www.smileycentral.com/?partner=ZSzeb008_ZNxdm006YYUS' target='_blank'><img src='http://smileys.smileycentral.com/cat/10/10_3_2.gif' alt='Drooling' border=0></a>


:laugher: :laugher:
 
Discussion starter · #35 · (Edited)
I am in no hurry since I have all winter to study and plan.
So no trip to Johnsons Speed shop yet. I am going to keep my eyes open though. :winker:
Rumrunner, I know those big blower look impressive but, I kinda like the smaller "sneak attack" ones..
 
#37 ·
Dwight said:
That is true. I know I could get to what I want NA but I was thinking 600-650 hp would be easier with a supercharger. What did your 600hp system consist of?
Click to expand...
502
oval ports all done up
single plane intake/single 800 carb
CMI's
and only a 222/230 110 576/598 hyd. roller
P600B with a radial impeller
 
#39 ·
RumRunner said:
Dwight,

It depends on how much power you're trying to make. With a 502, and a good 250 (like a Blower Shop unit) you can make 700 HP with a single King Demon or Dominator pretty easily. Unless you're trying to run a lot of boost you're going to be happier with a smaller blower since it will accelerate much faster. The difference in heating is going to be very minimal. The only down side to the smaller blowers is that they don't look as impressive!
Click to expand...
What do you mean they don't look as impressive? :shocked:
Are you teasing my litle baby blowers as cfm call's them? :angry1:
Now your gonna give me a BLING inferiority complex. Now what do I do??? :confused1 :confused1
 

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