Carb mods needed to prepare for supercharger.
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Joined: Jan 2001
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From: College Station, TX, USA
Carb mods needed to prepare for supercharger.
Supercharging my car is a long way off, but I would like to know what is neccesary to prepare a carb for a supercharger. Anything different in prep between roots and centrifugal?
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82 Camaro:
350
Erson cam, ported heads,Comp Cams 1.6:1 rocker arms
Edelbrock Performer RPM intake, Holley 600
Crane Hi-6 ignition, Accel supercoil
TH350 tranny with 2500 stall.
Eibach Pro Kit
SLP 1 3/4" headers
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82 Camaro:
350
Erson cam, ported heads,Comp Cams 1.6:1 rocker arms
Edelbrock Performer RPM intake, Holley 600
Crane Hi-6 ignition, Accel supercoil
TH350 tranny with 2500 stall.
Eibach Pro Kit
SLP 1 3/4" headers
Junior Member
Joined: Apr 2001
Posts: 82
Likes: 0
From: Moline, IL
i would imagine there would be a difference since the carb will be pressurized with centrifical. i had a buddy with that setup but i dont know what he had done to the carb.
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former 305 crossfire fuel injection
350 cubes
hooker headers
750 vac secondary
700r4 with shift kit
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former 305 crossfire fuel injection
350 cubes
hooker headers
750 vac secondary
700r4 with shift kit
Supreme Member
Joined: Feb 2001
Posts: 1,607
Likes: 0
From: Houston, TX
Car: 2001 Camaro SS
Engine: Almighty LS1
Transmission: T56
procharger has a kit to convert holley, edelbrock and now even demon carbs to be prepped for their centrifugal superchargers...
isn't that nice of them?
they also sell the carbs pre-converted for it
isn't that nice of them?
they also sell the carbs pre-converted for it
Supreme Member
Joined: Sep 1999
Posts: 7,072
Likes: 13
From: Philly, PA
Yeah, BIG difference between roots and centrifugal. Centrifugal blowers are tougher to use with carbs. The carb must be sealed up but still properly vented internally and the fuel supply system must be pressure-compensated so that as you go into boost and the fuel bowls pressurize that gas will still be able to push it's way past the needle ans seat into the fuel bowl.
Can it be done? Sure. Is it more work, money and hassle? Sure.
Personally, I like using roots blowers with carbs. Their spinning lobes do a fantastic job of atomizing the incoming A/F mix and getting mixture distribution very even between cylinders. Also, the latent heat of vaproization of the fuel flowing through them acts like an intercooler, offsetting much of the heat put into the mix by the "inefficient" lobes of the roots blower. Last, but not least, the blower lobes act as a one-way valve into the engine- reversion pulses in the intake can never reach the carb and cause weird calibration problems. THe best part about a roots blower is that boost is instantaneous. You get full boost from the instant you nail the throttle through redline.
Net net of all this: Carbs and roots blowers were made for eachother.
On the other side of the coin EFI and centrifugal blowers are an equally good pairing. Easy to install for one and more compact. EFI is also much more easily adapted to compensate for positive pressure in the intake and doesn't really give a hoot about intake reversion pulses. Also, the more efficient centrifugal compressor doesn't heat the air as much as a roots blower. THat's a good thing since dry-flow EFI intakes (not TB) don't benefit from the cooling effects of atomized/vaproized fuel flowing through them to cool the intake tract. Boost, however, is not really instantaneous- it builds with RPM, unlike a roots setup.
Just some stuff to think about.
Oh yeah- you can buy a complete new roots-style blower for Small block Chevy from summit for about $1400. I know of no centrifugal blower kit that cheap.
Can it be done? Sure. Is it more work, money and hassle? Sure.
Personally, I like using roots blowers with carbs. Their spinning lobes do a fantastic job of atomizing the incoming A/F mix and getting mixture distribution very even between cylinders. Also, the latent heat of vaproization of the fuel flowing through them acts like an intercooler, offsetting much of the heat put into the mix by the "inefficient" lobes of the roots blower. Last, but not least, the blower lobes act as a one-way valve into the engine- reversion pulses in the intake can never reach the carb and cause weird calibration problems. THe best part about a roots blower is that boost is instantaneous. You get full boost from the instant you nail the throttle through redline.
Net net of all this: Carbs and roots blowers were made for eachother.
On the other side of the coin EFI and centrifugal blowers are an equally good pairing. Easy to install for one and more compact. EFI is also much more easily adapted to compensate for positive pressure in the intake and doesn't really give a hoot about intake reversion pulses. Also, the more efficient centrifugal compressor doesn't heat the air as much as a roots blower. THat's a good thing since dry-flow EFI intakes (not TB) don't benefit from the cooling effects of atomized/vaproized fuel flowing through them to cool the intake tract. Boost, however, is not really instantaneous- it builds with RPM, unlike a roots setup.
Just some stuff to think about.
Oh yeah- you can buy a complete new roots-style blower for Small block Chevy from summit for about $1400. I know of no centrifugal blower kit that cheap.
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