Supercharger vs Turbo

[NXcoupe]

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..

Actually a quad turbo top fuel car was experimented with back in the 70's and a quad turbo boss 429 was experimented with by Ohio George Montgomery in the old Gasser/FX classes. The quad turbo top fueler and some of Ohio George's stuff is available to view and read the history of at the Don Garlits Museum of Drag Racing in FL. It is well worth the trip there to see the history of drag racing and especially the top fuel stuff he has collected or is on display. The turbos were not competitive when they were experimented with in TF. They just didn't work for a lot of reasons. The trans that you guys mentioned isn't what they run. They actually run a direct drive, which is a clutch attached to a driveshaft. No transmission can survive the torque and power produced as evidenced by half of Don's foot missing from a trans explosion he experimented with back in the 70's. A TF engine only makes about 2k to 3k revolutions to make it down the track. The spark plugs melt by the 1/8 mile from the combustion heat and the engine detonates the other half of the track, which is why they come apart so much and have to be inspected after each run. Just thought I would throw out those tidbits.

 

[jabird]

Twin turbos are the only way to go for our cars. Easier to hook-up and horses to spare. Plus, if heat is a factor, turbos will always be ahead. Summer is coming and topless is the best!

 

[justinschmidt1]

Twin turbos are the only way to go for our cars. Easier to hook-up and horses to spare. Plus, if heat is a factor, turbos will always be ahead. Summer is coming and topless is the best!

Please explain what the hell your talking about? lol

I would say that twin turbos are the way to go however it doesnt seem like you understand why.

In order of hooking I would say a centri blower is best for hooking, then turbos, then last would go to the roots/kb type blower.

The turbos will definately make the most power and im still trying to figure out what you mean by turbos will be ahead, relevant to heat?

you realize that turbos have exhaust gases running through them?...doesnt exactly help with air temps when compared to something that does not have 1500 degree gases flowing through it.

 

[jabird]

Justin, I have been working with a performance shop that installs superchargers and turbos. Intake temperature is what I'm talking about. For example, a Pro Charger making 10 lbs of boost has intake temps about 155 degrees, while a turbo making the same 10 lbs of boost will have intake temps around 90 degrees. Assuming both settups are at 70 degrees nominal, and both have air/air innercoolers. I've heard about a new supercharger that uses coolant in tubing under the screws...could change everything! For now, I'm thrilled that my heat problem is gone, even with the A/C on!

 

[coleton22]

i found if u really dont have the money go on ebay and get a kit for around 2 grand yes its a headache to put in but its cheap and they are getting better and its a great way to start out plus when the turbos go out just got and buy nice one and bolt them on its cheap and it works and u can push a lot of power out them some of the kits on there

 

[justinschmidt1]

Justin, I have been working with a performance shop that installs superchargers and turbos. Intake temperature is what I'm talking about. For example, a Pro Charger making 10 lbs of boost has intake temps about 155 degrees, while a turbo making the same 10 lbs of boost will have intake temps around 90 degrees. Assuming both settups are at 70 degrees nominal, and both have air/air innercoolers. I've heard about a new supercharger that uses coolant in tubing under the screws...could change everything! For now, I'm thrilled that my heat problem is gone, even with the A/C on!

I did not know that lol...

I do know however that my vortech with a front mount intercooler has very cool intake temps...like 10 degrees above ambient usually.