Supercharger Vs. Turbo- Off the Line Results

[jibbby]

This is an old thread but suggests an interesting discussion and topic...

Root supercharger -

That will give you instant lowend torque like N/A since the charger is run directly off the crank...The engine turns and so does the charger immediately.....The down side is that the charger will use crank HP's to turn it...

Turbo charging -

Spool up time is needed to turn and operate the turbo so lowend torque is compromised greatly..However, the exhaust turbo is driven by the exhaust and not the engines crank so less power is used to run the turbo in comparison to a root charger...

So which would be faster? Well if both were equal in power output... The charger would be faster but the turbo is more effecient ... That's my take when comparing root chargers to exhaust turbo's...

There are other types of boost not discussed such as Centrifigal chargers and Variable vane turbo's.... Not as commonly used though as your every day exhaust turbo's and root chargers.....

Feel free to add to this discussion...

 

[scotturnot]

Wow, I just noticed Ryan started this thread in 2003. Guess we all know the path you went.

 

[SC400TT]

Wow, I just noticed Ryan started this thread in 2003. Guess we all know the path you went.

Yep, I got burned by the guy in Aussie on the distribution of the SC kit I was working on with him...No names being mentioned, but he is not a name on the site that has been putting these things together...He was going to be a dealer of the original kit from Andy, the first guy I know of that put together a SC kit for the car in Australia. I got so pissed by this guy's (not Andy) change of commitment to me that I decided "screw it" and went Twin Turbo for higher power... I do not think the guy ever put together a kit from Andy, nor ever sold one...I have never been in contact with him since...

Ryan

 

[jibbby]

That sucks Ryan, I can see how it would be very hard to go after this clown in Aussie land... I feel for you man.... Good thread never the less..

 

[lxsv8]

Assuming both car have about 300 rwhp. That way its easier to compare. Its not fair to compare a 600 rwhp ST with a 300 rwhp SC. When people stated that supercharger will give you power off the line is a myth. Not all supercharger will give you power off the line. Root Style like the Eaton M90 (Ford widely used this in T-Birds, 2003 Cobra and Jag use M112) will give "EARLIER" boost vs. centrifugal (like ATI, Vortech, Powerdyne, Paxton and so on) will give "LATER" boost.

People with supercharger (centrifugal) will have something called by pass valve (BPV). If the BPV is open, you will not get any boost. BPV only closed when it experience zero boost (-18 psi is the vacum for N/A motor).

The range is from -18 psi to what ever +** psi. Anything below zero psi the BPV would be open and all the forced air will escape. Therefore, most centrifugal supercharger would not experience any positive boost until 2-2.5k rpm and up.

Most people would ask, why can't supercharger get all its boost at lower rpm. Yes, you can setup your SC to have all the boost come in the lower rpm, problem would be upper rpm. You will blow your motor at higher rpm.

I can go on and on. This is the bottomline. 300 rwhp SC vs. 300 rwhp SC and assume everything else being equal.

0-60 root style supercharger
1/8 mile = hard to tell
1/4 mile = Maybe turbo

You must understand to achieve 300 rwhp, turbo might just need 8-9 psi vs. supercharger might required 10-13 psi.

My raptor centrifugal SC on v8 was achieving 310rwhp on 8 psi! Boosts from around 2500RPM to redline (and redlines to rev cut very quickly through the gears - auto trans)

 

[Boosted2.0]

For my money a propely setup turbo > SC every day. The key is not to pick a HP level but rather a performance goal. If your goal is 0 to 60 performance you can pick a smaller turbo that will spool every bit as fast as a supercharger and make great power. This is especially true un autos with a 2 step rev limiter.

Turbochargers are just more efficient - you don't have to waste all that power spinning them or worry about shucking belts etc.

 

[XR8tt]

Turbo's can be made to launch just as quick..
You need a different approach though..
Its more done these days with Ecu's controlling things like
Launch control etc...
Depends how serious you want to go.. In most cases its already in your ECU [stand alone] its just a matter of setting it up...
If rotating assembly is tuff enough a turbo will make 500 h.p with ease...
Besides in MOST cases too much power down low equals smoke and damage transmission...Oh another I have found! A turbo is much quicker off the line with auto as it has load on converter before lights change..
Turbo's being load sensitive...

 

[jibbby]

How do you get a huge single turbo to launch and spool up quickly? If you have an automatic tranny and a huge single turbo you are screwed, just my opinion....

Unless you have a Variable vane turbo setup it's just not happening..

The only way I can see a large turbo launching like a supercharger is if you have a "really small" turbo's that simply don't require that much spool up time.....

My two cents.....

 

[cribbj]

It's actually a lot easier with an A/T than a manual.

I'm no dragstrip guru, but do a search for a 2-Step Launch Controller and you'll see what I mean.

Edit: Forgot to include the reference for a Line Lock, which is what makes the A/T easier than the manual to launch:

http://www.hotrod.com/howto/49619_brake_line_lock_install/index.html

 

[jibbby]

Well John, I wasn't talking really about dragster applications but just your every day mid sized street rods that are setup with a very large single turbo system...

You're really going to be dogging it out of the blocks if you have a smaller motor like a 4 cylinder or even 6 cylinder that is housing a larger turbo system...

In regards to transmissions - I would think with a manual tranny you can atleast ride the clutch a bit at launch to get the rpms up (spool) with the turbo's...With an automatic tranny you can "break torque" maybe to try and spool up...I would venture to think a manual would give you a better chance to bolt at launch though...

With a V8 motor and good torque converter you can still achieve a decent launch whether or not the turbo spools up quickly or not... That is the advantage with big engine displacement and a good stall rate...

All I was saying with a supercharger you don't have to worry about all those variables...The crank turns and the charger turns giving you instant boost power...I just like the idea of that... Although, a nice turbo setup is nice too..

 

[cribbj]

A turbo won't spool just by revving the motor in neutral; the motor needs to have load on it before there'll be enough energy in the exhaust gas to spool it.

The line lock is what gives you the "brake torque" or load on the motor.

And yeah, a heavy car, with a little motor and a big turbo is a tough combo to get going. Add in a lightweight flywheel and a grabby clutch and it can be a miserable beast to drive in stop & go traffic. That's why many of us with Supras are going for the V8 swap.

I've often wondered how a Roots or a twinscrew would transform the 2JZ motor in the Supra. All that motor lacks is cubes and/or lowend torque, and a PD supercharger would sort that out. People are paying $10K to upgrade their 3.0l 2JZ's to 3.4l stroker motors, and I'll bet a SC setup would cost way less than that.

 

[Blizzy]

And yeah, a heavy car, with a little motor and a big turbo is a tough combo to get going. Add in a lightweight flywheel and a grabby clutch and it can be a miserable beast to drive in stop & go traffic. That's why many of us with Supras are going for the V8 swap.

I've often wondered how a Roots or a twinscrew would transform the 2JZ motor in the Supra. All that motor lacks is cubes and/or lowend torque, and a PD supercharger would sort that out. People are paying $10K to upgrade their 3.0l 2JZ's to 3.4l stroker motors, and I'll bet a SC setup would cost way less than that.

This is an interesting point.

I would be very curious to see if anyone had the resources, the desire, and the stones to put a PD blower on the 2JZ. I would bet that psi for psi, a Whipple would walk all over the stock twins.

 

[pwd]

I think that a PD blower would be the way to go, if going by seat of pants feel I have from the Whipple on my 1UZ at the moment, not even going WOT it just wants to fly, and that is on a low boost of about 8lbs.

But on the other hand my mate Lew has a 1J in his lite ace work van with a smallish single turbo and that thing is very responsive.

I am not that knowledgeable about turbos, its all about getting the numbers right isnt it, either huge horsepower and lag, or less horsepower and very little lag.

Shoot me down if you need to but I am just looking at the turbo side from basic dont know that much about turbos.

 

[Lextreme II]

How about a turbo and a twin crew or root?

 

[sonbum1]

According to the polls taken on this site in this forum, the GT40 is the favorite single turbo set up and the twin screw is the favorite super chager. So how about this comparison, a GT40 set up vs a Twin Screw set up. If anybody has either of theese set ups weigh in with times/dynos.

 

[XR8tt]

So many variables...Esp with turbo's..
There are heaps of ricers running 7 or 9 seconds with single turbo...
But there rules in drag racing they are allowed to run ecu's..
Yes we are talking about street application.. But then we want to
do the street light drags also..
The Whipple is a very hard to beat but I wouldn't put down a good turbo either...They tend to be easier on engines and transmissions...
On exhaust stroke there some pressure on piston, this makes it easier on rod bolts etc.. A single is hardly disadvantaged compared to twins as single has twice the exhaust flow...But there's so many combinations with turbo's !! Not just a.r but the trim of the wheels inside etc..
I have two WRX Subaru's one is auto the other 2.5 and manual... The manual doesn't really start making serious power till about 3rd gear.. Unless you drive like its stollen... Where as the auto? Using left foot to brake, it powers away hard from the start...
I also have a street Ford falcon with Dart block of 330ci. With two SC61/2's T3/4 Hybrides.. It has 600 odd rear wheel horsepower and my 60 Ft times are something like 2.4 seconds.. If I try too hard the tyrs just loose traction...The trans is Tremec TKO with twin plate clutch..
A friend of mine has a 4.0 sohc [same body] with turbo making 370 rwkw and its auto..
His 6ft times are well under 1 second...He has 28 inch X ply slicks where I run 235 RADIAL M/T slicks...But even if he runs his crappy Korean street tyres. His 60 Ft is still better.. His times are far more consistent also...
We all say my car would be 2 seconds quicker if it was auto..
Both cars run in the 11's ...Our family have both manual and auto trans with turbo conversions and the auto is much easier to drive and faster..Easier to strengthen trans also..

 

[cribbj]

How about a turbo and a twin crew or root?

Well David, in about three months, I'm going to have both a single turbo 2JZ motor, and an Eaton M112 sitting in my garage..... maybe Fate will bring them together.

 

[Boosted2.0]

How do you get a huge single turbo to launch and spool up quickly? If you have an automatic tranny and a huge single turbo you are screwed, just my opinion....

Unless you have a Variable vane turbo setup it's just not happening..

The only way I can see a large turbo launching like a supercharger is if you have a "really small" turbo's that simply don't require that much spool up time.....

My two cents.....

Nitrous and/or a 2 step will spool most anything

Seriously though - any turbo you have trouble spooling at the line is going to make more power than a supercharger ever would. Pick a supercharger and power level and odds are you can find a Turbo or two that delivers the same power that will spool off the line.

 

[jibbby]

Boosted you correct.... Yes nitrous launch with a big single turbo would work well in track application but not too practical in a street rod...

Infact, I have a friend here in LA with drag 2jz Supra dishing out nearly 1500whp with a powerglide mated tranny... Huge single turbo setup with of course the 200 nitrious shot to just get the turbo spooling from launch...That is the only way to compensate but again nitrous applications are not practical unless your car is only dedicated to track drag racing in my opinion.....

Agreed turbo sizing and power output is just about limitless where the superchargers can peg out... Although, if custom built you can mount some fairly large superchargers/blowers on just about any V8...Paxton makes a huge supercharger for the blown big block Chevy's and Fords...The challenge is always fitment when you have a hood sitting on your ride...

 

[XR8tt]

Paxton are centrifical and can fit anywhere...
A well sorted T04Z or Gt42 turbo would spool way quick enough!!
With 600 to 700 h.p.. Would be very quick street engine...
Some comments here seem to made by people that don't have boosted engines...