Will supercharging surpass turbo as best power enhancement?

[Turbo50Mike]

If SCs didn't make power, you wouldn't see them on every top fuel drag car out there, you'd see turbos instead. Some pure drag cars are experimenting with turbos, but they are the exception, not the rule.

For drag racing SCs are great. The power is right there when you want it. For the trail (similar to road racing a car), turbos are great. You don't see many SCs on a rally car, and you don't see turbos on many drag cars (except the compact car guys). Turbos work great with trail sleds the same way they work great for rally cars. When you are on the throttle the turbo spools up. You let off for a corner and the turbo is still spinning fast, making boost, and its there ready when you hit the throttle again. That overcomes the lag issue. In that sense, a turbo will actually make more power than a SC, because with a SC, the drive will slow down as the engine does through a corner, losing boost. That boost won't be there when you need it, but more boost will be created as the engine speed rises.

On a drag strip, the engine is staying at speed the whole way, so the boost with a SC will always be there.


Jim

Sorry brother, I don't even know where to begin with all of this - so get out your pencil since you've obviously done no homework on this subject.

First off, turbos are not allowed in top fuel! If they were, EVERYONE would have one. Why are they not allowed - You should check on drag racing history. Pro Stock used to have very loose rules a few years back, eveyone SWORE on mountain motors - "BIG CUBIC INCH MEANS BIG HORSEPOWER!" - Well, until Ingersoll came along with a twin turbo 262 cubic inch V-6 and ran with the 500 cubic inch motor. The motor guys went crying to IHRA saying that turbos were too much "technology" for the "nostalgic" Pro Stock class. He single handedly changed the rules are SCARED the NHRA with his car. Check this out for the FULL story...Quite an interesting read....

http://www.gnttype.org/misc/ingersoll.html

"You don't see many turbos on drag cars"???
No???? Check again. Just about every single class where turbos are allowed , the turbos are dominating . NMRA , PSCA, and FFW just to name a few all have multiple classes that allow turbos, and in all of those classes turbo cars are taking championships. From the Pro classes, to the drag radial classes, turbos are setting records. Who was the first to get a Mustang to 200 mph in the 1/4 mile - John Gullet in his 1992 Mustang - 372 inch motor with a single turbo.
Who was the first to take a drag radial car into the 7's? "Big Daddy" Dwayne Guthridge in his Single Turbo 1990 Mustang LX - (7.97 @ ~ 170mph) in 2002.
Who just went 7.66 @ 181 on the drag radials setting a new record? Rick Head in his twin turbo IROC.
(Are Ford Mustangs and Chevy Camaros compact cars?)

(Here are just a few videos from the Fun Ford Shootout at Englishtown this past July - All these cars are turbocharged, not one NOS or SC car in the field...Hmmmmmmm..)

http://www.turbomike.net/images/Pro1Qualify.wmv

http://www.turbomike.net/images/Pro2Qualify.wmv

http://www.turbomike.net/images/ProElim1.wmv

I will agree with you on one point - About that graph...It is total BS - Like you said, you need to compare apples to apples, but if you take a 1500CFM peak Turbo, and compare it to a 1500CFM supercharger, the turbo will still make more power. Why? Because of the area under the curve. The turbos wil make boost more boost at a lower RPM than a centrifugal supercharger, and that means more torque. Period. On top os that turbos take only 1/6th the power to drive since they are not gear driven, they use what would normally be wasted energy (heat in the exhaust gas) to drive the impeller. Exhaust gas temps after the turbine can be as much as 450 deg cooler - For those of you that have taken any science courses should remember the conservation of energy law - Where did all the heat go????

And no need to get me started about what the Buick Grand National did to GM, Chevy, and the Corvette. If you don't know the story, check Google- Football is starting.

MJB

 

[Turbo50Mike]

From the 2004 NHRA Rulebook, Section 12 "Funny Car", page 168

Section 1 - Engine

Any internal-combustion reciprocating 90-degree V-8, single camshaft, automotive type engine permitted. Multi and/or Overhead cam configuration prohibited. Maximum 500cid, minimum 490cid...

Dry-sump oil system permitted. Dry-sump tank must be mounted inside framerails. Turbocharger prohibited....--------------------------------------------------------------------------------




quote:
--------------------------------------------------------------------------------
From the 2004 NHRA Rulebook, Section 13 "Top Fuel Dragster", page 177

Section 1 - Engine

Any internal-combustion reciprocating 90-degree V-8, single camshaft, automotive type engine permitted. Multi and/or Overhead cam configuration prohibited. Maximum 500cid, minimum 490cid...

Dry-sump oil system permitted. Dry-sump tank must be mounted inside framerails. Turbocharger prohibited....

 

[Silverbullet]

DUDE YOU GOT IT TOGETHER

 

[Frostbite]

That's for sure!

So Mike, how about answering my question regarding supercharger vs. turbos for high altitiude applications?
Is there any benefit in running a supercharger for these applications?
We all know the turbos offer a huge benefit in this regard.
Thanks
Frosty

 

[Bakemono]

Multi and/or Overhead cam configuration prohibited. quote]
I think its BS that you cant run overhead cams. The musclecars guys' egos just cant take the fact that a DOHC V8 would totally blow away all the OHV V8s!
Its sort of like in NASCAR. They will never let Toyota run the kind of engine they want because they know that Toyota would have such a huge power advantage. Oh well, Im going to laugh when Toyota beats the domestics at their own game! 3 wins this year in the truck series. Not bad considering Toyota said they intended '04 to be a "learning" year. Im telling you, in '05 they are going to win the NCTS championship!
Long live overhead cams and multiple valves!
Hebi

 

[Turbo50Mike]

That's for sure!

So Mike, how about answering my question regarding supercharger vs. turbos for high altitiude applications?
Is there any benefit in running a supercharger for these applications?
We all know the turbos offer a huge benefit in this regard.
Thanks
Frosty

I'd have to say that in a high altitude application, both turbo and SC are very close.

But....Turbos have one slight advantage - Since SC's are gear driven, they spin at a predertimed speed. So let me just give you an example -

Let's say at 0 feet above sea level an RX1 with a SC at 8000 rpm makes 10psi of boost. And a RX1 with a turbo at 0 feet above sea level at 8000 rpm is set to make 10psi of boost.

Now take those sled up the mountain, and at 5000 feet above sea level, that RX1 with the SC at 8000 rpm might only make 8.5 or 9 psi of boost since the air is less dense. But the turbo RX1 at that same elevation is making 10psi of boost.

How could this happen??? Since the SC is gear driven, at 8000 rpm the SC impeller will always be spinning at 40,000 rpm (for example). So at 0 feet elevation or 5,000 feet, it's 40,000 rpm. However the lower density air will lower the compressed charge slightly.
But the turbo is still making 10psi at 5000 feet, Why?? Because the turbos are regulated by wastegates, the wastegate will only bypass when the intake manifold pressure reaches it's setpoint. So at 0 feet elevation, the turbo may be spinning at 75,000 rpm impeller speed to make 10psi of boost. But at 5,000 feet elevation the impeller will be spinning at 85,000 rpm to make that 10psi of boost. The wastegate will remain closed slightly longer therefore spinng the impeller faster, making more boost.

There does come a point of diminishing returns when the turbo is spinning beyond it's peak efficiency island and it starts making more heat than power. So it is possible that at 10psi you make less power than at 9psi since the turbo is beating the air so hard to make boost, that it becomes less dense. But a turbo properly sized, and not that close to end of it's peak CFM range shouldn't really have too much trouble with altitude compensation.

What is the exact difference between the two at high elevations? I'm not exactly sure, but agian, the difference is slight.
But the turbo is better.

 

[Turbo50Mike]

I agree with you Hebi...They are so scared of losing at their own game they won't change the rules. I guess they don't want any progression in the sport.

Oh, and you want to talk about another trend setter - Does anyone know the story of Smoky Yunick? That is a guy that took the rules, and twisted them so hard, they had to write ENTIRE rule books because of him.

MJB

 

[race24x]

I dont know any of the technical stuff like mike but about rules in NHRA they are called rules if you want to start another class go ahead but if you want to call it open mod then lets roll the Jet powered funny cars in and take everything. Rules are designed to keep the classes close I wouldnt be suprised to see the snowmobile racing rules change to limit the 4 strokes dominance unless the other sleds start brining on some new 4 stroke models.

 

[nhrxrider]

You don't need to sell me on the concept that turbos are cool and make tons of power. My friend is into turbo Dodges, and you wouldn't believe how embarassed a Vetter or Camaro owner will get when a 2.2 liter Omni GLHS toasts them. I owned a Plymouth Laser Turbo (2.0, DOHC, Eagle Talon clone) which, after just a couple home-brewed mods to raise power levels, was making almost 300 hp and was still a pleasure to drive on the street. But then, I could have had the same results with a properly set up blower, it just wouldn't have been as driver-friendly on the street. For drag racing, I know there are exceptions to every rule, and I know turbos can go fast. But fact is, class for class where turbos AND blowers are both allowed to compete, you'll still find an estimated 95% of the drivers run superchargers. I think its a pretty poor statement to say that a turbo is number one, period, in all areas and uses. Thats just not true. They each have their place, their strong points and their weak points.

Jim

 

[Turbo50Mike]

I dont know any of the technical stuff like mike but about rules in NHRA they are called rules if you want to start another class go ahead but if you want to call it open mod then lets roll the Jet powered funny cars in and take everything. Rules are designed to keep the classes close I wouldnt be suprised to see the snowmobile racing rules change to limit the 4 strokes dominance unless the other sleds start brining on some new 4 stroke models.

Yes, the rules are supposed to keep the racing close. But when you look at all of the classes where Nitrous, Superchargers, and Turbos are allowed, the turbo cars ALWAYS have the highest minimum weight requirement (i.e. Nirtous would be 2800 lbs, SC 2900lbs, and Turbo 3050lbs). Why? Because turbos make more power.

Now keeping the racing close is fine by me, but this thread is called "Will supercharging surpass turbo as best power enhancement?" And if you look what is happening in racing, you should be able to figure out what is making the most power.

Since there are no rules out on the trail you can put whatever you want on your sled. Just don't bellyache when you get beat by a turbo.

(P.S. I love ANYTHING that adds power to a motor. Nitrous, Supercharger, and Turbos are all alot of fun. And that's what makes racing fun - You want to see a good variety of power adders to keep it interesting, instead of a bunch of carbon copy cars.)

 

[Bakemono]

They are so scared of losing at their own game they won't change the rules.

You gotta love the fact that Toyota's first truck series win happen at Michigan Intl Speedway, right in Ford and GM's back yard!
Hebi

 

[peteracing]

TURBO50MIKE is wright all the way . it is mathematically impossible for a
roots or prop. supercharger to match max. power from a turbo. and besides, when do you think COMBUSTION used to drive a airplane turbine
will be replaced by an electric motor or else?

 

[nhrxrider]

As opposed to popular belief, turbos are NOT "FREE" power. They restrict exhaust flow, slowing down the charge if incoming air to the combustion chamber. They are a little more efficient than a supercharger, but in reality, thats because of belt friction on the SC more than the actual power required to spin it. This concept about heat creating the power is false...heat is absorbed at the turbo, true, because its a restriction and the exhaust flow is slowed there. Its the airflow from the engine that actually spins the turbo. Put a turbo in an oven...it doesn't spin on its own! The engine is an air pump, and the pressure created by that pump spins the turbo.

There is no clear cut answer to which is better...it will be a never ending discussion. Its like a Ford vs. Chevy argument...nobody will ever figure out who is right.

Jim

 

[slymax]

Centrifugal superchargers are just belt driven turbos. It's the positive displacement superchargers(twin screw) that make all the bottom end grunt. Whatever makes .......It's all good

 

[Turbo50Mike]

Normally I let posts like this go, but you seem to be spewing misinformation, and I feel compelled to correct you.

"As opposed to popular belief, turbos are NOT "FREE" power. They restrict exhaust flow, slowing down the charge if incoming air to the combustion chamber."

You are correct in that it is not "free" power. There is a small amount of energy required to compress the exhaust gas before the turbine wheel, but again, far less than required by a comprable supercharger. In addition to that, this has NOTHING to do with the speed of the incoming air to the combustion chamber! Most stock camshafts (and every turbo grind camshaft) have "Zero overlap" - This means that the intake valve and exhaust valve are never open at the same time. Since the exhaust valve is completely closed before the intake valve begins to open, there can be no reversion of exhaust gas back into the combustion chamber and therefore cannot "slow down the charge of incoming air" as you describe. Not to mention that the inake is pressureized from the boost from the turbo; so when that intake valve begins to open as the piston begins to make it's way downward, air (and fuel) rushes from the high pressure area (intake tract) to the low pressure area (combustion chamber) and this process is not "slowed" by any means.

"They are a little more efficient than a supercharger, but in reality, thats because of belt friction on the SC more than the actual power required to spin it."

Doesn't that mean that the supercharger is less efficient????????? :? :? :? :?
On top of that, it's not the "belt friction" that causes the loss. It is the fact that superchargers are gear driven, and it takes alot of crank HP to get that SC impeller to a speed fast enough to produce boost. Since the SC is a parasitic drag on the motor it is less efficient.

"This concept about heat creating the power is false...heat is absorbed at the turbo, true, because its a restriction and the exhaust flow is slowed there. Its the airflow from the engine that actually spins the turbo. Put a turbo in an oven...it doesn't spin on its own! The engine is an air pump, and the pressure created by that pump spins the turbo."

Could it be that we have found a flaw in the First Law of Thermodynamics? These turbos are taking heat and making it disappear like Keyser Soze?? (movie trivia, who knows it???)
Yes, put a turbo in an oven and it does nothing but get hot. But for good reason - The potential difference from the turbine inlet to the outlet is the SAME temperature. I.e. If the oven is set to 500deg, you have 500 deg on the inlet side of the turbine, and 500 deg on the outlet. There is no potential difference. On the engine, you have 1500-1600deg F exhaust gas temps on the inlet side of the turbine, and ambient temps (yes, I know, inside the downpipe temps are elevated higher than ambient, but for arguments sake...) - However when you measure the EGTs coming out of the turbine it will be 300-450 deg F cooler than on the header side. Of course it's not ONLY the heat that spins the turbine, but there is a good percentage of energy taken from the exhaust gas that spins the turbine wheel - Along with the air pressure/pumping action from the engine.

Did you ever do that neat little experiment in the 8th grade science class where the teacher has what looks to be a light bulb with a black and white paddle fan trapped inside of it. Then he takes a spotlight and shines it on the paddle fan and it begins to spin. Hmmm....How does that thing work if there is no air pressure in the bulb????? Amazing.

There is no clear cut answer to which is better...it will be a never ending discussion. Its like a Ford vs. Chevy argument...nobody will ever figure out who is right.

Jim

That's an easy one...I've proved this many times - Ford.