950 HP Eaton TVS Supercharger

[81DaytonaPaceCar]

says a guy with only bolt ons....

but seriously though.. what kind of torque are those engines making at 2500rpm?

Sure you can throw a large turbo on it.. but you wont make boost untill 5000rpm and your done by 7000rpm.. that would be VERY annoying to drive on the street. I think that is the message here.

I would actually disagree.

800 torque at 2500 RPMs is essentially undrivable on the street...you won't even be able to creep away from a light without turning the tires over.

You would want torque to build evenly through the band rather than having an on/off switch.

[JoeliusZ28]

thats 800 Torque at WOT though jeff. You dont need 2500 rpm to creep off the line in most cases either unless youve got a really high stall auto.

[DanO]

I would actually disagree.

800 torque at 2500 RPMs is essentially undrivable on the street...you won't even be able to creep away from a light without turning the tires over.

You would want torque to build evenly through the band rather than having an on/off switch.

its not an "on/off" switch. Thats what the throttle is for. Last time i drove away from a traffic light i did not have it to the floor (ok maybe i did... but i drive a 3.1L V6)

With the supercharger it gives you the "ability" to have whatever torque you want at any instant. If you want to regulate that on the street, its easily possible with the bypass control. Heck, in my cobalt, i could have 0 boost in first gear if i didnt want it.. just bypass all of it... I could even make it drive like a turbo car (no boost till 3000rpm)

I'd be to the contrary, a turbo car is much less drivable becuase if your slowly driving from the light at part throttle, all of the sudden your torque will ramp up without changing throttle position.

The supercharger will have nearly constant torque (essentially for arguments sake) at a given throttle position. It will drive like a more powerful NA car.

Dont get me wrong, i think turbo's are great and can make awesome power, but to have the "effect" of a larger NA engine.. you need a blower.

What about this scenario.. your in 5th gear cruising down the road at 2500rpm. 850lbft will give quite a bit of acceleration without having to downshift.. something a 950hp turbo car wont.

[81DaytonaPaceCar]

thats 800 Torque at WOT though jeff. You dont need 2500 rpm to creep off the line in most cases either unless youve got a really high stall auto.

Not true...max torque is rarely made at WOT...in this case it shows 850ish at 4800 and 700ish at 7K RPM.

The chart doesn't show what it makes at 2500, but I would be curious.

My point is, and we don't know this, if say we're making minimum torque at idle, and we make say 600 at 2500 and 850 at 4800 RPM, that is a dramatic increase over a very short period of time.

This will in essence make everyday driving practically impossible at higher RPM.

An example...although the example is running turbos, it does show what happens when when you hit the meat of your torque curve and you're making excessive amounts in a street application:

http://videos.streetfire.net/video/5...-WWW_61460.htm

Long story short...850 torque is not a streetable motor, unless you're going to drive it like an old lady, and then, what's the point of having it?

[JoeliusZ28]

No, max torque is not usually made at WOT down low, but your still going to be making a LOT more at WOT than you are at 1/8th throttle. thats my point.

im kind of confused... you are saying the dramatic increase over a short time is what makes it unfriendly... well a car with a peaky power band is going to increase a heck of a lot more steeply than that around 4 or 5k RPM. That is sort of contradictory

Im a huge fan of a flat torque curve because its predictable. If you have a sharp increase up top you wont be able to control it, and youll probably put the car into a wall if you arent ready for it when it hits... just like the example video you gave.

[DanO]

i agree joel

the supercharger gives you instantly and exactly the torque you command with the throttle... (up to the peak torque availible at that rpm)

something a turbo car never will.

[81DaytonaPaceCar]

im kind of confused... you are saying the dramatic increase over a short time is what makes it unfriendly... well a car with a peaky power band is going to increase a heck of a lot more steeply than that around 4 or 5k RPM. That is sort of contradictory

Im a huge fan of a flat torque curve because its predictable. If you have a sharp increase up top you wont be able to control it, and youll probably put the car into a wall if you arent ready for it when it hits... just like the example video you gave.

If you have a sharp increase ANYWHERE you won't be able to control it, regardless of where you're at in the RPM range, especially for 850 torque.

Somehow, this motor spiked to 850 at 4500 RPM and stayed flat through redline. The issue is how did it get there?

Again, we really need to see the whole curve to assess it, but let's make a couple assumptions.

1. This motor makes 150 torque at a 1000 RPM idle.

2. This motor makes max torque at 850 at 4500 RPM.

This means that you're increasing 700 torque only over 3500 RPM, or a 100 torque increase per 500 RPM through your everyday-driving-around RPM range.

Pretty big spike, even assuming it's linear, which it probably isn't...just looking at the torque curve we do have, it's flat at 4600 RPM. How did it get there? Are we making 800 at 4000? Are we making 700 at 3500?

Too big an increase too quickly...essentially an on/off switch metaphorically (I was not being literal).

No street setup could handle that...waste of power...as the Nelson boys showed us...

EDIT: This has nothing to do with turbos or SCs...for this example.

[DanO]

"Tractive Effort" is limited by normal load and coefficient of friction.

If your torque exceeds the maximum "Tractive Effort" that the tire/vehilce combination is capable of then there will be slip. Typically when the 'slip ratio' of the tire exceeds its peak rated value.

Basically what your saying is that there is too much torque for the street..

This is where computer controls come into play!!

I agree completely that 850lb-ft is far too much for street tires in first gear. Heck my FSAE car with 45lb ft can light em up at will. HOWEVER, with computer controls you can incorporate many different levels of Launch, traction, and other controls to allow you to accelerate to the peak limits allowed under that circumstance.

Its really not that hard, and if your using an aftermarket ECU anyhow, many of them have these features already.

Like the FSAE car below.. any idiot could accelerate it to its maximum potential.. Step 1. Push in clutch Step 2: Push down accelerator pedal to WOT Step 3: Release clutch and hit shift button on steering wheel when redline comes up.

This car had too much torque for how light of a vehilce it was, but those issues were easliy solved with electronics.

If your going to invest that much into an engine.. at least put some nice controls behind it

[c0ncEpT]

says a guy with only bolt ons....

Lets not get our panties in a bunch over difference in opinions now boys.

Ok with a 20% parastatic loss from the drivetrain that 950 is now only 760 at the wheels and thats maybe 100 more than the big KB cobra guys make on 3xx cubes.

I'm not saying its not a lot of power because yes its a crap load of power but I think there is more power to be had by using FI on a 400+ cube LSX motor

[Superman09]

they are giving that set up away actually. They perform the dyno run and whoever can hold their right hand around the headers for the entire pull wins the engine. But then they put the engine in a car with a stick that you must shift with your right hand.

Would be much nicer if that was in a car and rwhp, still sick to say the least

[81DaytonaPaceCar]

Basically what your saying is that there is too much torque for the street..

This is where computer controls come into play!!

I agree completely that 850lb-ft is far too much for street tires in first gear. Heck my FSAE car with 45lb ft can light em up at will. HOWEVER, with computer controls you can incorporate many different levels of Launch, traction, and other controls to allow you to accelerate to the peak limits allowed under that circumstance.

If your going to invest that much into an engine.. at least put some nice controls behind it

Yes, electronics will solve everything.

However, as we saw in the Nelson video, even in 3rd gear it would effortlessly smoke the rears.

Based on that example, and the assumption that they're making 1000 hp and 1000 torque, it would demonstrate that while electronics would solve the problem, you've overbuilt the motor for your application.

In this case, a streetable motor.

Simply retarding the motor's performance with electronics does not change that fact.

This would be different if the torque curve was more of a slope than a plateau, but regardless of that, I highly doubt this example was ever intended for the street.

Sure you can throw a large turbo on it.. but you wont make boost untill 5000rpm and your done by 7000rpm.. that would be VERY annoying to drive on the street. I think that is the message here.

And this isn't quite correct either. Even on my car, boost starts to spool at 2000 RPM and will hit max boost by 3500 RPM or so and hold it there to the redline.

Very tractable, predictable and consistent, especially once you make max boost...and demonstative of streetable power with a sloping torque curve with no electronic limiters.

[WMCC Gary]

Jeff Quit Wasting Time and just accept it, Joel is always right.

[DanO]

Yes, electronics will solve everything.

However, as we saw in the Nelson video, even in 3rd gear it would effortlessly smoke the rears.

Based on that example, and the assumption that they're making 1000 hp and 1000 torque, it would demonstrate that while electronics would solve the problem, you've overbuilt the motor for your application.

In this case, a streetable motor.

Simply retarding the motor's performance with electronics does not change that fact.

This would be different if the torque curve was more of a slope than a plateau, but regardless of that, I highly doubt this example was ever intended for the street.



And this isn't quite correct either. Even on my car, boost starts to spool at 2000 RPM and will hit max boost by 3500 RPM or so and hold it there to the redline.

Very tractable, predictable and consistent, especially once you make max boost...and demonstative of streetable power with a sloping torque curve with no electronic limiters.

yes.. but your motor does not produce 950hp. The thing about turbos is that you can have a good low rpm response... or you can size them for high flow and pressure ratio. To increasingly get more airflow and power from the same displacement engine, you will inherently create more turbo lag or just lack of boost at that rpm. its a fact of life!! Any turbo that spool's quickly at low engine rpm will be the limiting factor at high engine rpm. Turbo's are not designed for Wide airflow ranges.. if you can keep the operating range narrower you will be more efficient and able to achieve higher PR.

I'm not going to argue any more.. because its pointless.. I've been through this stuff a million times.. I understand what your getting at.. but dont just think about first second and third gear... what about 5th and 6th when your at 70mph and 1500rpm...

if your not able to place your tires at the brink of loosing traction in EVERY gear and every RPM... then you arent accelerating to the maximum ability of your tires and you dont have enough torque..

[81DaytonaPaceCar]

yes.. but your motor does not produce 950hp. The thing about turbos is that you can have a good low rpm response... or you can size them for high flow and pressure ratio. To increasingly get more airflow and power from the same displacement engine, you will inherently create more turbo lag or just lack of boost at that rpm. its a fact of life!! Any turbo that spool's quickly at low engine rpm will be the limiting factor at high engine rpm. Turbo's are not designed for Wide airflow ranges.. if you can keep the operating range narrower you will be more efficient and able to achieve higher PR.

I'm not going to argue any more.. because its pointless.. I've been through this stuff a million times.. I understand what your getting at.. but dont just think about first second and third gear... what about 5th and 6th when your at 70mph and 1500rpm...

if your not able to place your tires at the brink of loosing traction in EVERY gear and every RPM... then you arent accelerating to the maximum ability of your tires and you dont have enough torque..

Hmmm...didn't think we were arguing...I believe we agree on most premises thus far...

But, to your points above, I agree.

My motor doesn't make 950 hp...but 99.999% of the turbos in the world do not engage at 5000 RPM...that was my only point.

However, to get off the subject a bit, there is a way around all the shortcomings of a turbo.

Simply make sufficient torque at a low RPM to get the vehicle moving before the turbo engages. Accomplished by a long stroke motor, with a turbo set up to engage when at the top end of that motor's torque curve.

Ideally a big block, but any long stroke motor will suffice.

For a BB Pontiac or Chevy, they'll make max torque on their own around 3000-3500 RPM (give or take). Set the turbo up to hit max boost just north of this and you "should" have a near perfect combination of torque off the line with boost pushing you through the upper RPM ranges.

Hit the next gear, and you're still in the power band of either scenario, torque or boost, and continue it through the cycle.

Adios turbo lag.

Unfortunately, most turbo motors are set up from small displacement, small stroke configurations...so most people assume that turbo lag is just something inherent in the system.

Regardless of all that mess, the thing that intrigued me was that this LS motor made max torque at 4600 RPM and flat-lined from there...not a motor intended for the street, but what happened before 4600 RPM? How did it get there?

Now I'm curious...

EDIT: I forgot to add that if you want to see turbo efficiency, check out truck and heavy equipment motors...not car motors...cars have had it wrong for 50 years...thank you Europe...

[DanO]

turbos are much better suited to low rpm engines like the truck and heavy equipment industry.. thats because they have such a narrow operating band and can be sized much better. Not to mention, the larger the turbo, the more efficient it can be. Sometimes 80-81% adiabatic (for the compressor side). Automotive has the largest handicap for turbos.. a WIDE operating range .. and customers that dont want lag..this is why they will never hit the efficiencies of the truck market. Its all about thermodynamics and fluid mechanics..

As for the lag topic.. your not 'eliminating' lag.. your just having a big enough engine to compensate for it. I still dont agree with your combination.. but hey i guess were all entitled to our opinions If you want alot of power out of a normal sized engine.. your turbo will have lag.. no 2 ways about it.. If you can go around that.. i know alot of turbo companies that will pay millions. I'm constatnly aware of what is going on in the turbo industry and you have only a few options.. reduced lag sacrifices high rpm perforamance and vice versa.. Technologies like VGT, and seqential turbos help reduce the comprimise.. but there is still a LARGE comprimise

As for the rest of the graph, i do not have that.. if i get it, i'll post it. All i know is that it was at 850 lb-ft at 2500rpm.. so you can extrapolate from there.