Do I need an intercooler, yes. Intercooling does several things, but these are the most important to me - it reduces engine temps and keeps the motor operating in its green zone; provides the foundation for the next motor; and it reduces knock. To remind, 9.66:1 compression.
I had to chuckle at the reason why you're against it, because it makes it easier to pull the motor. For the stuff I do, if the motor is coming out in less than 20k miles, I did something wrong in the build - thus, I abhor fixing what I could have done right the first time, so most of my motors don't come out of their car. There are exceptions (aka lessons) where that isn't true - but, for the most part, it's what I do. But certainly, I have friends that if there's a small drip; the motor comes out - I joke with them that need to install engine removal zippers...
I'm not against nitrous, it's just not what I use because it doesn't fit with what I do. Most of my cars are either brutal daily drivers, or autocross. I don't drag race, almost never show, so bottle filling just doesn't work.
Supercharging, I've done it on 3 different motors and I'll never do it again... I've found them to be too temperamental. That said, the procharger you have is about the only one that I'd even consider because it can be intercooled fairly easily..... funny, and as I typed that I reminded myself that I might be putting a magna charger on my 06 GTO....
It isn't just pulling the motor, it's all around accessibility. And the cost of the intercooler with its additional plumbing. But I certainly won't stop you from doing it! The benefits are unquestionable. I'm just talking about how I would do it.
Sounds like an awesome build, I look forward to the results!
-BC
I always chuckle when people talk about working space... here's the Buick
And here's my other major, current project (3.6l VVT Cad motor with turbos)
that above thing I said sounded harsh.... not meant to be harsh - just a PG glimpse into my first thought
Senior Member
What type of superchargers did you use?Originally Posted by stoneshrink
Roots or twin screw?
Paul
Senior Member
thought I would tag along here.
We too plan to build a twin turbo BBB for the 70 Skylark for street. Current target is an 8.90 pass. Car weighs 2750 with a BBB. Chassis work will be first, and trying to decide to backhalf the car, or not. Engine build is later down the road. Current build is the V6 turbo for the GN. Almost done with it.
86 GN, all factory options, engine build in progress
72 Skylark Convertible, 462, TH 400
72 GSX Clone 464, TH400, 3:42. 10.71 @126mph best
We build GM carburetors and specialize in custom built Quadrajets
www.quadrajetpower.com
mark@quadrajetpower.com
roots blowers - 6-71, and a B&M on two different motors
but, uh, aren't twin screw and roots blowers the same thing? did you mean centrifugal or roots?
Last edited by stoneshrink; 12-10-2011 at 06:46 AM.
2750? wow, that's taking the Twinkies out of the Buick....
Here you go: http://kennebell.net/KBWebsite/Commo...romcatalog.pdf. Love my twin screw!
Steve B.
67 GS 525 Buick Stage IV
66 GS Convertible
65 GS HT
63 Riv
02 Subaru WRX Turbo
03 Ford Cobra Convertible (Factory Supercharged)
Senior Member
There are 2 types of positive displacement superchargers. One is the roots type and the other is the twin screw.
There is also a design which is a cross between the two used by Eaton/Magnuson.
The roots supercharger is not an air compressor and produces manifold pressure simply by blowing more air into the engine than the engine can pump. Hence the word "Blower" used for description. The air is pushed around the outside of the rotors in the case from the inlet to the outlet side and most of it is prevented from returning where the rotors mesh. As the air pressure is increased on the outlet side so is the air temperature. Because there is clearance between the rotors some of the heated air gets returned to the inlet side where the rotors mesh giving the roots blower poor thermal efficiency.
The twin screw supercharger is a true air compressor. The screw and auger configuration compresses the air down the length of the case until it is discharged out the bottom. Since the air is always moving away from the inlet, heated outlet air cannot return to the inlet giving the twin screw design a high thermal efficiency. http://www.lysholm.us/showroom.php
The Eaton supercharger has roots style rotors.The rotors are twisted so the air is moved down the length of the case like the twin screw giving it many of the advantages of the twin screw.
There are 3 main suppliers for twin screw street superchargers.
http://www.lysholm.us/
http://www.kennebell.net/KBWebsite/H...s/Homepage.htm
http://www.whipplesuperchargers.com/
And the Eaton supercharger
http://www.magnusonproducts.com/
http://www.eaton.com/EatonCom/Produc...Superchargers/
All of the above companies supply their superchargers with a bypass valve.
When boost is not needed the valve is open and the supercharger is bypassed. When you are just cruising it takes less than 1 hp to drive the supercharger.
Step on the gas pedal, the valve closes and instant boost.
The Axial models are for EFI and the Radial models are for carburetors.
Because the twin screw is much more efficient than the roots, intercooling is not so much of an issue
and at lower boost is usually not needed.
It's expensive, but Whipple makes intercoolers that sit in the intake mainifold
Kenne Bell liquid cools their superchargers.
Unlike turbochargers, boost begins to build from an idle and you can have max boost by 2000 rpm
There is no boost lag which is important when running a manual transmission.
Having to wait to regain turbocharger boost after a shift is frustrating.
Paul
Last edited by pmuller9; 12-10-2011 at 02:08 PM.
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