Supercharger vs Turbo

[Spyder]

Yeah, he also goes by wolverine.

his car is insanely fast. im a huge fan of that setup

 

[Downshift]

Maybe someone could answer this for me. My dad is an oldschool muscle car/carb type guy so when I talk about turbos benifts or fuel injection he always has questions that I can usually answer. The other night though we were talking about how top fuel dragsters use SC and not turbos and we couldnt really figure why not. Anyone know why?

 

[Thomas_W]

Maybe someone could answer this for me. My dad is an oldschool muscle car/carb type guy so when I talk about turbos benifts or fuel injection he always has questions that I can usually answer. The other night though we were talking about how top fuel dragsters use SC and not turbos and we couldnt really figure why not. Anyone know why?

my guess would be instant torque off the line since they use proshifted transmissions

 

[Downshift]

Maybe someone could answer this for me. My dad is an oldschool muscle car/carb type guy so when I talk about turbos benifts or fuel injection he always has questions that I can usually answer. The other night though we were talking about how top fuel dragsters use SC and not turbos and we couldnt really figure why not. Anyone know why?

my guess would be instant torque off the line since they use proshifted transmissions

Ya thats the only thing we could figure. Would be pretty interesting to see a top fuel dragster that turbo though....

 

[BMOREstang]

Yeah thats basically the only reason they use them. The roots style superchargers they use give the same air charge (power) to the engine at all engine speeds, from a dead stop to the end of the 1/4. However it takes 750 to 1000 horsepower just to make those superchargers work their magic.

 

[GregT94SCC]

All in all a good writeup, but to be honest it could all be opinion without giving us concrete numbers. You need to mention adiabatic efficiency (which is of course the MOST important measure of a compressor) and compare that among your subjects. Also the roots/twinscrew will "windmill" when there is vacuum. When "windmilling" a KB twinscrew is purported to use roughly 1-3 HP. Most street driving is done when the motor is making vacuum (part throttle). As far as I know, Autorotor is the only manufacturer of an automotive twinscrew, and KB is the only supplier of it for Ford applications.

Obviously you have chosen to turbo after evaluating your needs and conducting your research. I have done the same, and we have come to two different conclusions! I think the key difference isn't in the research, but in what we want out of our cars. Research done after you buy will usually be biased (in support of your Hypothesis), so neither of us are really equipped to aid someone in making an informed decision.

To really do a proper writeup, ideally there would be one car, one motor and two different power adders to run tests with. We would need experts for each system being installed and for tuning the car. There would have to be some baseline configuration that would remain unchanged (cam MAF, TB CAI etc.). Magazines have done things like this before, but I don't trust their results; I see mags as more detailed parts catalog than a source of unbiased info.

 

[wickedcobra]

All in all a good writeup, but to be honest it could all be opinion without giving us concrete numbers. You need to mention adiabatic efficiency (which is of course the MOST important measure of a compressor) and compare that among your subjects. Also the roots/twinscrew will "windmill" when there is vacuum. When "windmilling" a KB twinscrew is purported to use roughly 1-3 HP. Most street driving is done when the motor is making vacuum (part throttle). As far as I know, Autorotor is the only manufacturer of an automotive twinscrew, and KB is the only supplier of it for Ford applications.

Obviously you have chosen to turbo after evaluating your needs and conducting your research. I have done the same, and we have come to two different conclusions! I think the key difference isn't in the research, but in what we want out of our cars. Research done after you buy will usually be biased (in support of your Hypothesis), so neither of us are really equipped to aid someone in making an informed decision.

To really do a proper writeup, ideally there would be one car, one motor and two different power adders to run tests with. We would need experts for each system being installed and for tuning the car. There would have to be some baseline configuration that would remain unchanged (cam MAF, TB CAI etc.). Magazines have done things like this before, but I don't trust their results; I see mags as more detailed parts catalog than a source of unbiased info.

I am REALLY glad someone finally said this. Turbos are very cool, If you have a shit load of money to throw at it. And dont mind just droping the car off for tuning. But I have seen way more turbo cars die then supercharged. Like you said, the air change has huge changes on a turbo car.

 

[Shocker98GT]

Maybe someone could answer this for me. My dad is an oldschool muscle car/carb type guy so when I talk about turbos benifts or fuel injection he always has questions that I can usually answer. The other night though we were talking about how top fuel dragsters use SC and not turbos and we couldnt really figure why not. Anyone know why?

Couple of reasons really.

1: A Roots blower is the only blower that the class allows, twinscrews aren't allowed nor are turbos.

2: Nitromethane releases it's own oxygen when burned. The cars aren't starved as much for air (for the power delivered, I mean) as they are fuel, opposed to a gas motor. Running lean is a huge problem, and they cram so much of the fuel mixture into the cylinders that they are just on the verge of the hydraulic lock, they run a 1.7:1 air/fuel ratio (which is stoichiometric for nitromethane). Running lean=burnt metal, running rich=hydrolocking, the tuning is the most important part of a successful run because nitromethane is so touchy. A roots blower has a predictable boost curve. Turbo? Now that'd be nearly impossible or at least VERY hard to get right just due to the nature of a turbo's boost curve. Consistency and predictability is key. Aside from that, the flame front for burned nitromethane is around 7050 degrees F. Turbo system, even one built of super-exotic materials, wouldn't be reliable AT ALL and would be very lucky to make it through the run, probably through staging realistically. Top Fuel cars have enough issues as-is.

3: The exhaust of a top fuel dragster is actually designed to produce downforce, around 800lbs or so, that's why the pipes are turned upwards. Having one turbo exhaust outlet vs 4 exhaust outlets on each bank would complicate this, aside from the turbo being a huge exhaust restriction in itself especially in this scenario. A car making 8000hp can't afford such an exhaust restriction compared to something like a street motor.

4: Turbo plumbing, BOV, turbo itself (it would take a MASSIVE turbo to provide that much oxygen) equals more weight, a big consideration for a car that only weighs ~1200lbs.

5: Chassis is only rated to 330mph by the NHRA anyway

6: Engine of the cars are broken down after every single pass. The tons of piping used to turbo such as car would obviously severely complicate such a matter.

That obviously isn't every reason, but some of the more compelling ones IMO..

 

[Downshift]

Maybe someone could answer this for me. My dad is an oldschool muscle car/carb type guy so when I talk about turbos benifts or fuel injection he always has questions that I can usually answer. The other night though we were talking about how top fuel dragsters use SC and not turbos and we couldnt really figure why not. Anyone know why?

Couple of reasons really.

1: A Roots blower is the only blower that the class allows, twinscrews aren't allowed nor are turbos.

2: Nitromethane releases it's own oxygen when burned. The cars aren't starved as much for air (for the power delivered, I mean) as they are fuel, opposed to a gas motor. Running lean is a huge problem, and they cram so much of the fuel mixture into the cylinders that they are just on the verge of the hydraulic lock, they run a 1.7:1 air/fuel ratio (which is stoichiometric for nitromethane). Running lean=burnt metal, running rich=hydrolocking, the tuning is the most important part of a successful run because nitromethane is so touchy. A roots blower has a predictable boost curve. Turbo? Now that'd be nearly impossible or at least VERY hard to get right just due to the nature of a turbo's boost curve. Consistency and predictability is key. Aside from that, the flame front for burned nitromethane is around 7050 degrees F. Turbo system, even one built of super-exotic materials, wouldn't be reliable AT ALL and would be very lucky to make it through the run, probably through staging realistically. Top Fuel cars have enough issues as-is.

3: The exhaust of a top fuel dragster is actually designed to produce downforce, around 800lbs or so, that's why the pipes are turned upwards. Having one turbo exhaust outlet vs 4 exhaust outlets on each bank would complicate this, aside from the turbo being a huge exhaust restriction in itself especially in this scenario. A car making 8000hp can't afford such an exhaust restriction compared to something like a street motor.

4: Turbo plumbing, BOV, turbo itself (it would take a MASSIVE turbo to provide that much oxygen) equals more weight, a big consideration for a car that only weighs ~1200lbs.

5: Chassis is only rated to 330mph by the NHRA anyway

6: Engine of the cars are broken down after every single pass. The tons of piping used to turbo such as car would obviously severely complicate such a matter.

That obviously isn't every reason, but some of the more compelling ones IMO..

Well thats about 6 reasons more then I could figure out. Thanks for the info man makes a lot more sense now.

 

[GaryG]

i got my mind set on going the turbo route, but could some1 list the pro's and con's on twin turbo vs. single turbo?

im looking to do either twin 57mm turbos or a 70mm turbo...goal is 700rwhp, all street driven, maybe take to the track once a yr, have some fun on the street...also, how soon (rpm wise) do u think i would start seeing boost?

 

[Dalamar]

main benefit of the twins is you spool up quicker. should start seeing boost around 2K.
I had my eye on doing a twin kit on my car, twin 57's was what I was looking at as well.

 

[GaryG]

after talking w/ the guy im buying the GT from, hes a turbo guru, im gonna go w/ a 76mm turbo

 

[Dalamar]

cool cool!
I don't know a bunch about single kits, but the cons' of twins I'm aware of is there's more piping/connections, 2 bov's 2 of all that junk, and more heat ie. heat soaking can be an issue.
should be a sweet build

 

[GaryG]

the heat problem is the #2 reason im going w/ a cobra r hood, #1 being they just look bad ass on these cars

but thankfully he is a dealer for Precision Turbo so he can get a great deal from them, and im having a custom hotside done by him an his brother...might of heard of them C&B Motorsports

 

[forcefed5pt0]

ive been thinking on selling my kennebell, just so i can try a single turbo.. they say you only live once!

 

[GoldenHP]

Very well written. I must say that i am a turbo person myself. There are more pro's than con's for running a turbo (in my opinion).

exhuast leaks being the major

 

[GoldenHP]

IMO turbo is the only way to go. POer comes on fairly fast as long as the turbo is sized correctly to the engine combo, you make more power with less boost, and not everyone has one. I have been in a single turbo 5.0 that is putting down about mid 500's and i must say, that thing is stupid fast when you puch it. ive never seen anything take off like that before, its insane. But the cool part, its a stock cam so it idles perfectly, its as calm as an old lady when you keep your foot out of it, and you get better gas mileage compared to a supercharger.

+1

 

[98GTnSC]

lag isnt as bad on our cars as you hear about it with the imports. we've got twice the cylinders and in alot of cases twice the displacement(even tho we dont hav BIG v8s) therefore even with 1 bigger turbo it wudnt b AS bad as sum wud think. but YES there will b lag with NE big turbo even with the twin setup. just not as much. if ne1 knows of a GOOD single turbo kit for the 4.6 2v let me kno. thats wut im wanting 2 try

 

[Dalamar]

I've got the Hellion kit on my 2V and it is amazing.
Highly recommend!!

 

[NXcoupe]

+1 on the hellion, no wait time and they fit really well. Kit's are very complete too. I am a supercharger and nitrous guy, but I am going to fool with a turbo car here in the future.