smokinHawk

iTrader: (48)

since a super charger takes created power, torque from the crank shaft and a turbocharger takes wasted power, ehaust the turbocharger will produce more torque everything else being equal.

Iv_z28

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by smokinHawk:
<strong>since a super charger takes created power, torque from the crank shaft and a turbocharger takes wasted power, ehaust the turbocharger will produce more torque everything else being equal.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">In that case turbocharger would also produce MORE power, and the q. was about two cases with equal power, i.e. why torque on SC comes highter in RPM. I don't have FI on my car, but I believe explanation is very simple - SC is directly connected to the engine, the higher engine spins, the more SC spins, while turbo reaches its max spin velosity at lower RPM, determined by the amount of friction in the turbine, and doesn't spin any faster [SC is made to spin even faster even though friction rises]. Therefore generally torque on SC doesn't go down as fast as on the turbo setup => lower torque is required for the same hp numbers.

I also believe that going with a larger turbo, which would reach max boost at higher rpm, would move that torque to the right and increase max hp, but that would also create turbo-lag.

SS00Blue

Yup. A turbo will... (take notice S/C guys) ALWAYSSSS!! make more torque than a... (take notice) centrifugal S/C, if they are both sized properly.

The Centri-S/C builds boost dependent on engine RPM, where the turbo does not. Max boost on a Centri is ONLY at max RPM, where a turbo climbs the boost hill at MUCH lower RPM and holds it for as long as you're between the ditches. There's the diff...

If you want torque, then bring on the boost at low RPMs, just like the Roots-style, but with MUCH less heat! Viva la turbo! Long live the expense of installing a turbo... <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />

SC-

<small>[ December 21, 2002, 02:00 PM: Message edited by: SS00Blue ]</small>

ChevyNo1

I've noticed that the SC guys running around the same RWHP as me ( 531 ) have lower torque #'s, like 450. I was 531/538 on 8psi with my TT. How do the torque curves generally compare?

- Dug

LS1astro

Too sum it all up if you both have say 8psi max boost and the turbo builds it through the whole curve including down low where the valves are open for a longer time because the motor is spinning slower allowing more A/F to enter the chamber giving it more torque.

RICE ETR

iTrader: (3)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Too sum it all up if you both have say 8psi max boost and the turbo builds it through the whole curve including down low where the valves are open for a longer time because the motor is spinning slower allowing more A/F to enter the chamber giving it more torque.
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">yup... early boost equals torque....

Nickn20

I am glad to see someone answered this right! phew! lol nitrous does this as well.

Black LS1 T/A

Another opinion:

SC is RPM dependent.
Turbo is exhaust-flow dependent.

SC boost seems to curve like this:

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">code:</font><hr /><pre style="font-size:x-small; font-family: monospace;"> --
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-----/</pre><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">... gradual boost to about 3000, the norm of it around mid range, a bit of a spike at peak RPMs.

ie, when I could get traction to see some lower RPMs, my 10 PSI max was 5 at WOT, then 8 for the most part (4500 to 6200), then, peaking at 9.5 or 10 above 6300. Spinning on the street was an instant 8 # peaking at 10#.

A4 guys with a high-stall converter might fool you on the torque advantage, though. The high stall made my RWTQ number quite high. It also made my HP curve flatter. (Stock motor: 486 RWHP / 487 RWTQ )

Having big cube motor with a SC reminds me of the feel of a turbo. GOBS of torque down low. My dyno was 527 RWHP / 651 RWTQ. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

<small>[ December 24, 2002, 08:40 AM: Message edited by: Black LS1 T/A ]</small>