acidpad

ive been trying to research this for a while now without posting anything (like for 2 months) until i had more information, but that not going as well as i would have hoped. what ive been pondering is having a setup with both a turbo and a super charger.

Unlike when you do a TT, my idea is to not have them run in parallel , but in series. That is to say, have the turbo feed the supercharger.

The idea isnt so much to have them couple their powers to make a large bost sum, but more so to make a more consistant amount of boost. Superchargers traditionally have good lowend boost, and die off toward higher RPM, whereas turbos are opposite that. So if i have the supercharger make the power in the lowend, and the turbo kick in for assisting the super in the mid range, and have the turbo take over in the high rpms basically.

Has anyone ever seen it done ?

Are there reasons that its not done often ?

can anyone see any drawbacks to the setup ?

any input on this would be helpful.

Thanks

bad_turbo

the main reason I can think of that most people won't do it, is cost. Not to mention it will be more show then go. Since the motor can only handle so much boost anyways, one power adder would make plenty of power on its own. It would look cool, though. Maybe twin turbos blowing into twin carbs sitting atop a 6-71. You could definitely make it work, Just not practical.

acidpad

the practicality of it is that you have the power both in the low rpm range, and in the high rpm ranger, whereis either one of them would be lacking if it was just one type of power adder. its kind of like why some people use NOS ina turbo setup ... to give the kick in the low until the turbo gets going.

Cronic3rd

To have all that you don't need to use a turbo and a s/c. Just match the turbos perfectally or get a s/c you can spin to the sky. Not to mention the paracitic losses would be huge.

Dan W

Not if the supercharger is properly sized... only a too small of a supercharger will die off on the high end.

Youe observation isn't exactly wrong either... You have to consider the power it takes to turn a supercharger vs a turbo. With equal amounts of boost the turbo will make a little more power the blower because of this.

Another thing to consider here is adiabatic efficancy... that is how much heat the compressor adds to the air as it pressureizes it. This efficancy directly affects the charge density going into the motor. Centrifical compressors (turbos and centrifical superchargers) tend to run at efficancies of about 60-80%. Roots superchargers tend to be below 50% while lyschlom screw compressors like kenney bell and whipple are in the same range as the centrificals... so even though both systems may be boosting to the same psi, the centrifical and screw supercharged setups will be getting a higher mass airflow into the motor and make more power.

You can make up most of the losses by running an efficiant intercooler and keeping the boost at the manifold the same as it was before you added the intercooler.

614Streets

Ive seen it in older car mags. The guys name was rick dobbertin he made a nitroused big block 65 nova with twin turbos feeding a 6-71 , he also made the "never to be topped" trailer queen the j2000, which had two blowers, twin turbos and nitrous oxide. He also made something called the earth trek which can drive anywhere, maybe he crossed the world with it ocean and all. I heard his wife divorced him.

Just do a google search on rick dobbertin
or visit
http://www.dobbertinhydrocar.com/J2000%20Engine.htm

http://www.dobbertinhydrocar.com/Nova%20Engine.htm


1965 CHEVROLET NOVA SS
FRAME 2" X 3" MAIN RAILS – 1.75" CAGE
ENGINE CHEVROLET 454 LS-7
INDUCTION TWIN HOLLEY 750 CFM CARBS
TWIN ROTO-MASTER TURBOCHARGERS
BDS 6-71 SUPERCHARGER
6-PORT NOS NITROUS SYSTEM
WATER-ALCOHOL INJECTION
IGNITION MSD 7AL-2 AND DISTRIBUTOR
CONVERTER B & M 11" COMPETITION
TRANSMISSION B & M COMPETITION TURBO 400
REAREND DANA 60 – 4.56 RATIO
SUSPENSION 4-LINK – COIL-OVER SHOCKS – FRONT
LADDER BARS – COIL-OVERS – REAR
BRAKES 4 JFZ DISCS
WHEELS CENTERLINE 15 X 3.5 – FRONT
CENTERLINE 15 X 15 – REAR
TIRES PNEUMANT 5.60 X 15 – FRONT
McCREARY 33 X 15 X 15 – REAR
SAFETY DEIST FLAME-OUT FIRE SYSTEM
5-POINT SAFETY HARNESSES
TWIN PARACHUTES








1985 PONTIAC J-2000
FRAME 1.625" STAINLESS STEEL
ENGINE CHEVROLET ALUMINUM 350
INDUCTION HOLLEY 1050 CFM CARB
TWIN ROTO-MASTER TURBOS
TWIN MAGNACHARGER
BLOWERS
20-PORT NOS NITROUS SYSTEM
WATER-ALCOHOL INJECTION
IGNITION MSD 7AL-2
MSD DISTRIBUTOR
CLUTCH HAYS TRIPLE DISC
TRANSMISSION LENCO 4-SPEED – 3.10 LOW
REAREND DANA 60 – 5.13 RATIO
SUSPENSION MACPHERSON STRUTS –FRONT
COIL SPRINGS – REAR
BRAKES 6 WILWOOD BILLET DISCS
WHEELS MONOCOQUE 15 X 3.5 –FRONT
MONOCOQUE 15 X 20 – REAR
TIRES PNEUMANT - 5.60 X 15 – F
MICKEY THOMPSON –
33 X 21.5 X 15 – R
INSTRUMENTS 11 AUTOMETER GAUGES
SAFETY DEIST FLAME-OUT FIRE SYSTEM
5-POINT SAFETY HARNESSES
PARACHUTE





I cant recall a race car made, it should work quite well.

83 Crossfire TA

iTrader: (2)

The reason that it’s done is that it’s not practical.

First, WRT to your assumptions about superchargers and turbos, turbos can be made to spool in any range that you want, you just need to size it correctly. Where superchargers work depends on the drive ratio and type. Roots and other positive displacement blowers will build boost right off idle, while centrifugal compressors do nothing till you get things really spinning.

Just about any compressor could effectively generate more pressure then what a gas engine can use, but not always the volume. Running them in parallel does nothing for volume, but allows you to generate much more pressure. This does little for performance, if anything it hurts it some since most compressors are not efficient at low pressures and now you have 2 stages adding heat to the charge. FWIW, most turbos do not work well under about 5-10psi and typically are happiest at pressure ratios in the 2-3.5:1 or more range (about 14-40psi or so), where gas engines very rarely work well at over 30psi.

On a diesel where you can run 40, 50, 200psi boost it makes much more sense to build 2 and 3 stage setups.

ME Leigh

Don't TT Toyota Supra's have Sequential T12B Turbo's. They make 320 hp from a 3.0 liter I6.