Centrifugals and Low End Torque

[SolarFlare]

I’ve never been in a race where I’ve said to myself about the other car, “uuuffff that torque got me!”

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[Burkey]

had 2 cars with positive displacement blowers and 2 with centrifugals and both centrifugals made more hp but less tq .I had more fun and the overall faster cars were my centrifugals ..never was my car slower down low or anywhere in the power band with a centrifugal nor did they heat soak and lose performance like my PD cars did after 3 or 4 runs in a row ..

I think you might be mistaking “bottom end” for peak torque.
Could be wrong, but it’s highly unlikely (all else being equal) that a centri is making more torque at below say 4k than a PD blower.

 

[Burkey]

I have read some posts where people running different centri's have commented on a seat of the pants felt decrease in low-end torque.

Maintaining the stock low end torque with a centri would be OK, since the mid-range and top-end would be there. Loosing low end torque would not be OK.

I am familiar with the "torque boosters" that are available for the Paxton/Vortech set ups and I understand how they work and see the benefits, albeit with an increase in inlet temp.

Would like to know if in fact anyone has a dyno graph before and after on Paxton/Vortech/Procharger on the low end of the RPM scale, with our without a torque booster.

If you were coming from an NA/e85 setup and converting to centri/98, it’s entirely likely that you’d notice something missing up to a certain point. Given that this isn’t your situation, I don’t see that you’d find it missing anything more than you are already.

 

[cib24]

I doubt any torque loss before the centrifugal comes on boost is all that noticeable, but the theory makes sense that you may see loss before you enter the positive boost zone at 3.5-4k RPM. A supercharger is belt driven and causes a drag on the engine and drivetrain, thus requiring power from the engine to feed the blower via the belt. So, low down when the centri is still in vacuum and not yet making positive boost, it's not unreasonable to think there could be a bit of horsepower and torque loss compared to a N/A car due to the extra drag. Kind of like having the A/C on and noticing low down before the A/C clutch disengages that the A/C is having a small effect on max power.

Why this matters at all to anyone when just pootling along I have no idea. The centrifugal setup is all about building power progressively to a peak near redline, to somewhat mimic the N/A setup but with 200-500 more horsepower by the time you are nearing the rev limiter. The benefits from this setup is that you will still have some traction off the line and by the time the supercharger starts to sing around 3.5-4k RPM you're laughing as you get that "Vtec-like" hit all the way to the rev limit.

When you race you use all of the revs anyway.

 

[cib24]

Also worth keeping in mind that the Centrifugal setups use a more traditional air-to-air front mount intercooler rather than a chargecooled water-to-air setup like a PD which sits between the supercharger and the lower intake manifold. As a result, the centrifugals don't heatsoak as badly or as quickly.

In any case, see below a 2018 GT stage 2 procharger P1X on 93 making 11.28-12.34 PSI vs. a 2018 GT stage whipple on 94 making about 10 PSI.

Please try to ignore the ultimate power and torque figures given these were different cars and different dynos despite both being essentially stock minus an H/X pipe. Focus on the torque curves to see the difference in power delivery.

Procharger P1X Stage 2

Whipple Stage 2

 

[Zinc03svt]

Plus nobody with these kinds of questions really care to add what kind of tire they are going to run 90% of the time...? Sure a PD blower on a super wide DR or bias ply is fun once the tires are heated. What are your bottom line goals? So many factors and variables folks.

 

[solshinobi]

I'd like to ask you Centri guys a question. I live in an area where there are mainly Hellcats and Vettes. How did these races play out? Many of these will be from a dig. Some will be from a roll. I want to know if you had to play catch up.

Forgive my ignorance on this but i just haven't seen this play out.

 

[schmeky]

revinto7 and others,

Thanks, that's good info. I realize there's a trade off with anything. Just didn't want the lower torque production to be excessively "soggy". I have built and helped build a bunch of SBC's in the past and some of those with high lift and high duration cam profiles, coupled with less than ideal converter and rear gear were not much fun on the street. This is different from the topic, but in my mind is possibly a similar comparison to the centri.

I was about to order a Whipple, but I know this is going to require lots more investment into cradle supports, wider wheels and wider, stickier tires, etc. I know a centri will require some additional upgrades as well, but I like the idea of the "hit" coming on more progressively.

Heat soak is another matter as well since I live in a hot, humid region. I know Whipple and EB have addressed this better than any other PD set up, but the centri's seem to be better in this respect.

Appreciate the input.

 

[revinto7]

I say buy what you like ,on a 10 speed car on the street or even on the track the centrifugal will just be a better smoother more linear power delivery that will less likely hit/shock the tire down low allowing you to have better traction then the mid and upper rpm is actually where the centrifigul and the coyote both shine .

 

[cib24]

I'd like to ask you Centri guys a question. I live in an area where there are mainly Hellcats and Vettes. How did these races play out? Many of these will be from a dig. Some will be from a roll. I want to know if you had to play catch up.

Forgive my ignorance on this but i just haven't seen this play out.

This comment kind of makes little sense. If you both start in the optimal gear and punch it the car with more power, lower weight, better aero, and better gearing will win as with any other race. If you are worried about racing from a 30 mph roll in 4th gear then you would probably lose because the other cars are automatics and would downshift to put the car in the right power band...

 

[80FoxCoupe]

I'd like to ask you Centri guys a question. I live in an area where there are mainly Hellcats and Vettes. How did these races play out? Many of these will be from a dig. Some will be from a roll. I want to know if you had to play catch up.

Forgive my ignorance on this but i just haven't seen this play out.

My car runs well with the smallest blower available for a coyote. If a hellcat or Vette is quicker/faster, it's a bad bitch. No love lost. Bottom line, I ain't scared.

 

[revinto7]

revinto7 and others,

Thanks, that's good info. I realize there's a trade off with anything. Just didn't want the lower torque production to be excessively "soggy". I have built and helped build a bunch of SBC's in the past and some of those with high lift and high duration cam profiles, coupled with the a less than idea converter and rear gear were not much fun on the street. This is different from the topic, but in mind is possibly a similar comparison to the centri.

I was about to order a Whipple, but I know this is going to require lots more investment into cradle supports, wider wheels and wider, stickier tires, etc. I know a centri will require some additional upgrades as well, but I like the idea of the "hit" coming on more progressively.

Heat soak is another matter as well since I live in a hot, humid region. I know Whipple and EB have addressed this better than any other PD set up, but the centri's seem to be better in this respect.

Appreciate the input.

look years ago a centri on a 9:1.1 compression engine with 8-10 psi was SOGGY !! these are 12:1.1 engines with 10-11 psi i can tell you they are anything but soft . Also they spend little time below 2500 rpm so it really does not matter .
at the time 2010 i had an 03 Cobra pulley tune Steeda cai mac prochamber and mac mufflers it Dynoed 471/500 13.5psi on a very accurate and true dyno jet !!
on the same dyno my 07 Shelby Gt had a pypes x pipe a vortech V3 si trim on 10.5psi at 6500 it made 491/434 both were manual both had cats and passed nys emmissions one had PD blower one had centri -i ran both against each other numerous time with my Fiance then and she could drive very exceptional .the both cars would be so close most of the time she would have me 3/4 of a car in the cobra untill 3rd gear then i would pull a whole car and creep until my 5 speed would run out of gear .we both switched cars and she would get me 1.5 cars the whole way in the shelby . the cobra was 11.40 123 mph car my shelby 11.30 127mph car .just to give you a little idea how similar the performance was but were the power was ..the cobra felt brutal the shelby was smooth but turned on like a light switch around 3400 ..the cobra 2nd gear up through 4th felt even and drama free the shelby would rev like a chainsaw and be on the chip faster than you could row it if you didnt expect it and it was violent and scary through the mid and top it would give me the rollercoaster feeling in my stomach as it pulled .for the record 3 years later in 2011 my Fiance was Killed i Built my Shelby in memory of her and also kept my mind occupied at the time .I ended up 10:1 compression 3v block stock cubes billet crank and rods /manley piston custom comp blower cams with 5 angle port polish 3v heads with 1mm over on valves vortech v3si 14psi innovatorswest 6% crank damper tremec t56 magnum xl 3.73 gear full tokico adjustable 8 way shocks carbon fiber driveshaft ect .. car made 735/534 8200rpm i ended up setting it back a little for the street to 685 @7600 it was a 10.20 138mph 3v at the time very solid performer .. GOOD LUCK WITH YOUR BUILD ! I am sure you will be happy with any of the blower choices
















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[revinto7]

My car runs well with the smallest blower available for a coyote. If a hellcat or Vette is quicker/faster, it's a bad bitch. No love lost. Bottom line, I ain't scared.

agreed your car is no slouch !!!

 

[cib24]

Don't forget, adding a blower is like $10k. Lots of cash to add to a depreciating asset but I'd probably do it if they were easier and cheaper to get a hold of, but by the time you pay to ship and import them here to the UK it's really hard to justify the outlay.

 

[revinto7]

here is my Built 3V it kicked a lot of ASS at the time and a lot of others wanted no part of it ..everyone thought it had a Pushrod in it !!

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