Supercharger Vs. Turbo- Off the Line Results

[cribbj]

You missed my point.

I'm not talking about "optimising" the setup for each one. My point is to keep the cars as identical as possible, and keep the peak HP the same, but just making their boost a different way. No 2-steps, line locks, NOS or any other type of advantage.

Then do a faceoff.

 

[XR8tt]

Turbo and auto over 1/4 is quick..
But add a manual and there would be some time lost in 60 Ft times...
Keep in mind low power levels usually means higher compression ...
With high comp turbo engines there's very little lag...
As said too many variables...

 

[jibbby]

Well if it's a 0-60mph race, or light to light race I would pick the root charger as you would get absolutely no lag time from idle as apposed to the others... So with the root charger you will get a better launch everytime which may just be enough to win a short distance race..... More torque usually at lower Rpms with the root chargers....

Whether the root charger can hold off the others up to 60mph I don't know for sure though...

1/4 mile I may take the turbo....

 

[stevechumo]

Here's another way to look at it. Take three identical cars, and equip one with a turbo, one with a centrifugal SC, and one with a PD SC, and size the setups so that they all make 400 RWHP, maximum; this is important. Nobody will be allowed to have a HP advantage.

Obviously each one will make his peak 400 RWHP at different RPM's. I'm thinking the PD machine will make his at a fairly low RPM, the centrifugal will be next, and finally the turbo at the highest RPM.

Now have a 1/4 mile runoff. Here's how I predict it'll go:

The PD car is going to come out of the hole the quickest. Maybe even his 0-60 times will be the quickest.

The centrifugal will be 2nd out of the hole because he's still making some boost off the line, just not as much as the PD car.

Then, the centrifugal guy is going to start reeling the PD in because the PD's boost curve is flat, but the centrifugal's is still rising.

Somewhere down the line the turbo is going to start catching up to the centrifugal because his boost curve is rising faster than the centrifugal, and he doesn't have any belt losses, only a restricted exhaust system (from having a turbine "blocking" the exhaust).

So I'm thinking the winner will depend on how much lead the PD guy was able to grab at the start. IMO, it's whoever has the largest area under the HP curve who will win.

I would think somebody like Hot Rod Magazine has already done this?

Same peak hp? Sounds interesting, because same psi varies between the efficiency of each boost system. So this would conclude at any "higher" RPM or speed, the turbo will be the winner? Any other factors or variables?

I also think a mild boost comparison is more appropriate because the turbo always wins at high boost.

 

[XR8tt]

Another advantage with turbo's is at high altitude they simply spin faster and make "near" the same power they would at sea level..

So when you hear high power levels at altitude ?? If they have corrected power due to air density lost due to altitude as in N/A / S/C engines etc.. It's not quite true, as the turbine simply spins harder to make up same boost pressure..... Here in Aussie its hardly an issue as we don't have much altitude...

 

[rms]

This discussion is really about 'horses for courses'.
The graph is from a Whipple supercharged race car.
Blue is boost in kpa
Red is rpm
Green is speed
Black is throttle position.

The car is exiting a 39kph (24mph) hairpin and accelerates to 124kph (77mph) in the one gear. Rpm on exit is 2189 and negative boost.
This has taken 2.695 sec and 187 ft.

From a standing start a turbo may be superior BUT from rolling through this hairpin the SC car is long gone.

 

[JustenGT8]

Well if it's a 0-60mph race, or light to light race I would pick the root charger as you would get absolutely no lag time from idle as apposed to the others... So with the root charger you will get a better launch everytime which may just be enough to win a short distance race..... More torque usually at lower Rpms with the root chargers....

Whether the root charger can hold off the others up to 60mph I don't know for sure though...

1/4 mile I may take the turbo....

My car will run 0-60mph in 3.7 secs on my dodgy street tyres (that was @ 430rwhp)......i'll stack that up against a roots blower any day

If you want a performance car then turbo will win in 90% of situations....but a good SC can come close and for all manner of reasons is still a valid alternative.

As i said, simple physics has the turbo as the winner but real world needs mean there's still a place for the SC. I'm still keen to marry the 2 and see what results

 

[jibbby]

Well Justen, how about if your car was equiped with a root blower that was dishing out the exact same horsepower as your current turbo setup? You may post a faster 0-60mph time...Like in 3.5 seconds... No? I not why? When the engine crank turns the root blower turns. When the exhaust speed increases the turbo spins.. See the difference?

Also I never knew turbo's spin better and faster in high altitude...That sounds cool if you live up in the mountains and are turbo charged.....Many times I have driven up high altitude mountains and felt the power decrease noticeably in my N/A vehicles...

 

[XR8tt]

;


I didn't explain that too well .. On some high alt dyno runs they add power as a correction.. This is acceptable on n/a engines.. But the turbo STILL keeps adding boost up until wastegate opens.. There will be some drop in power but not much..
Turbo's were widely used on ww2 planes so they could fly at high altitude...Piston engines back then...The T04 goes back to these times...

 

[cribbj]

From a standing start a turbo may be superior BUT from rolling through this hairpin the SC car is long gone.

Erol, please expand on this; both of these statements are just the opposite of what I would expect.

Those of us who drive turbo Supras rarely try to race anyone from a standing start as we're at a clear disadvantage without any boost at launch. Supra owners always try to race from a roll so that we're on boost immediately.

Coming through a turn as you described, if there's already load on the motor, I'd expect a turbo car to perform well. Maybe not with the "instant" boost that the SC has, but certainly better than it would from a standing start?

 

[rms]

John,
I assumed that most people meant a drag race standing start where a turbo can be loaded against an auto trans brake to make boost. A manual trans car will need anti-lag to make some boost and will be a lot more difficult to get off the line.

For rolling starts, if you can keep the rpm up and need some throttle to maintain speed (or a bit of left foot brake), then you will have less turbo lag. It will also depend on how long you have been under brakes and how much the turbo slows down.

If the Supra was in 2nd gear at a constant 2000rpm and you floored it, is there immediate light up the tyres ?

It depends on a lot of factors apart from turbo v sc. Rpm range/gearing/traction levels/time on throttle v time off throttle etc.

I dont have comparable data logs from a turbo vehicle but turbos have been tried on vehicles running in the same competition as the car the logs came from, and while they are spectacular to watch and comparable on the faster corners, from the slower corners and shorter straights they lack the immediate response.

Like I said 'horses for courses'

 

[JustenGT8]

Well Justen, how about if your car was equiped with a root blower that was dishing out the exact same horsepower as your current turbo setup? You may post a faster 0-60mph time...Like in 3.5 seconds... No? I not why? When the engine crank turns the root blower turns. When the exhaust speed increases the turbo spins.. See the difference?

LOL i can suck eggs Jibbby I can get more boost than i need off the line so even if the roots can generate more you are traction limited anyways.

I'll conceed it 'may' be easier to get the roots off the line consistently but if both cars get their 'perfect' launch there would be nothing in it.

BTW it would take ALOT more work and expense to get 430rwhp from an SC setup that it would a turbo.

 

[jibbby]

Rev'ing the motor and brake torqueing at launch and or frying the clutch to spool up the turbo's isn't practical and shouldn't be considered when comparing the two boost applications...

For one it's kind of stupid looking to be rev'ing the motor while pressing hard on the brakes when about to start a race...You may scare your opponent out of racing... None track speaking...

Secondly, to be frying the clutch at launch to just get the turbo's to prematurely spool up is also stupid...Again the motor is rev'ing at launch and you will look desperate to get the lead on your opponent..Also the life expectany of your clutch goes right out the window...

Anyway, that's just my opinion on the two, maybe some people think that's cool..Who know's.....however, your either tweaking your drive train or frying your clutch when doing both regularly...

I will tell you from experience, it's alot more impressive and more fun to drive a car that has immediate throttle response...Like when you can blast off from idle at launch... Hense idle, hense hit the gas, hense light up the rears, hense stay in front from start to finish and win the race...... Just my take...

 

[JustenGT8]

Rev'ing the motor and brake torqueing at launch and or frying the clutch to spool up the turbo's isn't practical and shouldn't be considered when comparing the two boost applications...

For one it's kind of stupid looking to be rev'ing the motor while pressing hard on the brakes when about to start a race...You may scare your opponent out of racing... None track speaking...

Secondly, to be frying the clutch at launch to just get the turbo's to prematurely spool up is also stupid...Again the motor is rev'ing at launch and you will look desperate to get the lead on your opponent..Also the life expectany of your clutch goes right out the window...

Anyway, that's just my opinion on the two, maybe some people think that's cool..Who know's.....however, your either tweaking your drive train or frying your clutch when doing both regularly...

I will tell you from experience, it's alot more impressive and more fun to drive a car that has immediate throttle response...Like when you can blast off from idle at launch... Hense idle, hense hit the gas, hense light up the rears, hense stay in front from start to finish and win the race...... Just my take...

What a crock Jibbby. Maybe why you 'win' so many races is the guy you are racing actually isn't

Anyways, the only stupid thing i see in this thread now is mention of street racing :irked:

 

[Jake Breyck]

um, lex. are you sure about that -18? i dont think that number is possable. if your talking -18 PSIA (absolute) you are 18 psi below 0, so basicly 18psi less then outerspace. if you are talking -18PSIG (Guage) whitch i assume you are sence thats the normal use. then you are about 4 psi less then 0 basicly not possable eather way. motors pull good vacume but never close to 0 PSIA let alone below it. you would need dark matter for that ;-)

 

[Jake Breyck]

Rev'ing the motor and brake torqueing at launch and or frying the clutch to spool up the turbo's isn't practical and shouldn't be considered when comparing the two boost applications...

For one it's kind of stupid looking to be rev'ing the motor while pressing hard on the brakes when about to start a race...You may scare your opponent out of racing... None track speaking...

Secondly, to be frying the clutch at launch to just get the turbo's to prematurely spool up is also stupid...Again the motor is rev'ing at launch and you will look desperate to get the lead on your opponent..Also the life expectany of your clutch goes right out the window...

Anyway, that's just my opinion on the two, maybe some people think that's cool..Who know's.....however, your either tweaking your drive train or frying your clutch when doing both regularly...

I will tell you from experience, it's alot more impressive and more fun to drive a car that has immediate throttle response...Like when you can blast off from idle at launch... Hense idle, hense hit the gas, hense light up the rears, hense stay in front from start to finish and win the race...... Just my take...

WOW i guess every single pro race driver no matter what series from F1, top fuel, touring cars, rally, ect is a moron?

 

[XR8tt]

Rev'ing the motor and brake torqueing at launch and or frying the clutch to spool up the turbo's isn't practical and shouldn't be considered when comparing the two boost applications...

For one it's kind of stupid looking to be rev'ing the motor while pressing hard on the brakes when about to start a race...You may scare your opponent out of racing... None track speaking...

Secondly, to be frying the clutch at launch to just get the turbo's to prematurely spool up is also stupid...Again the motor is rev'ing at launch and you will look desperate to get the lead on your opponent..Also the life expectany of your clutch goes right out the window...

Anyway, that's just my opinion on the two, maybe some people think that's cool..Who know's.....however, your either tweaking your drive train or frying your clutch when doing both regularly...

I will tell you from experience, it's alot more impressive and more fun to drive a car that has immediate throttle response...Like when you can blast off from idle at launch... Hense idle, hense hit the gas, hense light up the rears, hense stay in front from start to finish and win the race...... Just my take...

Sheesh you seem dead against turbo's !!
A correctly sized turbo doesn't require what you are saying above...
Maybe an all out drag car with 100mm plus turbo but a turbo around 600 to 800 cft per min 600 to 900 h.p turbo..Would do the job...Btw most quick s/c and turbo cars have two step.. But we are talking drag cars again...So are you in above post!!! WRX's and Nissan Skylines etc don't go through that many clutch's...In any case most Lexus would be auto..
The rotating assembly on a turbo engine is approx 80 + h.p stronger due to no extra load on crank to spin that roots...
Either way Boost is better than N/A where there's no spool....
In both cases I'd say above 400 rwhp ... Some trans mods would be required..

 

[jibbby]

Well I guess I am stupid and a moron, you guys keep brake torquing and riding that clutch it's all good....

The turbo guys are blasting me.... So sorry.....

Just so you guys know I am not against turbo's at all, I just don't like the turbo lag and who does?... However, I do love turbo boost....

What's wrong with organized street racing?

 

[jibbby]

What a crock Jibbby. Maybe why you 'win' so many races is the guy you are racing actually isn't

Anyways, the only stupid thing i see in this thread now is mention of street racing :irked:

I win some and I lose some Justen but they always try... Just maybe I can take you out you Justin 0-60mph on a good day so take it easy there chief...However, I need a new tranny first as mine just gave up the ghost again the other day..:sleeping1: .Justin since we are talking a little smack I am sure I can get you out of the blocks so take it easy when you talk to me :smokin: (as Tony Montana would say).....Hense turbo 6 banger against Nitrous run V8...

Man, I am wearing out this turbo lag thing....

Yes a properly fitted turbo won't have too much if any lag as said in the above post...Infact, I personally think a properly fitted turbo is the best possible setup for an SC400/Soarer equiped with a good stall rate torque converter and the automatic tranny... We are just talking here fellas, no need to get hostile...I give turbo's big props...

 

[XR8tt]

Strange thing about turbo's ... If the converter is too loose.. It takes just as long to spool as they are load sensitive...
A good converter has load lower in rpm but takes up a little higher in rpm...The strange [??] part is in most cases you can't have too much power at the wheels anyway...
In most cases you left foot brake on converter and hold rpm at 1200 rpm.. When lights go green there's almost NO lag... You'd do this on any type of engine combo....Big engines don't really have excessive lag due to engine size..Unless your building a dyno queen and fit a way large turbo..
Its the same with Chevy and Ford aftermarket Induction systems.. There are performance road and there's drag and race combinations...
I must say though.. A big block with high compression built to run N20 is about the meanest cars I have seen in the 60 Ft ... I guess running c16??