razorclaw99

iTrader: (7)

i have a procharger but was just wondering.. if both style superchargers run the same boost, wont the roots win cuz it hits it right away while the centrifugal has to spool it up? i never even understood the advantage the procharger has.. like its not even as good as a turbo because it doesnt hit max boost once it spools, it takes little by little all the way to redline.. So if what im saying is true, then roots will win because it will hit max boost right away while centrifugal chargers wait to spool it up..

unless roots has some kind of disadvantage i really dont know of ?? Any opinions on this ?

EPP

iTrader: (22)

Roots (Positive displacement) blowers do produce power much lower in the RPM band, but typically lose steam as the rpm goes up. A lot of Maggie owners complain that the blower is done at 5000 rpm. A top mounted blower also soaks in all the heat from the engine, as heat rises, and it is harder to intercool them.
We see '03-'04 Cobras and Ford Lighning trucks on our Mustang Dyno good for only one run, after that they lose on average 50 rwhp. Bob

99Z28LS1

iTrader: (4)

yeah, the roots blowers heat soak and are done after a few runs, prob why soo many cobras do N20 to cool them down and gain power all in one. they make crazy power down low, but loose steam up top

SonofaBish

iTrader: (5)

don't roots blowers have more parasitic loss too?

lilbuddy1587

iTrader: (1)

Thats why you need to compare a Twinscrew to a Centri. Twinscrews dont lose their "steam" up top and are MUCH more efficient (less heat).

tmaschm

So it makes sense for the Cobras to use the roots style blower, because of the way it produces power down low. That way it compensates for the lack of power that the Modular motors produce in that range. Because modular motors are better at higher RPM. So in our case for all around power for our pushrod V8 the centri would be a better choice. Am I right???

wannasupra

typically tho, a positive displacement blower uses more power to spin, generates peak boost sooner, and is more difficult to cool

centrifugal supercharger is basically a belt driven turbo, you can use an air to air intercooler, and they're fairly easy to tune because the boost is so linear

turbos have the least parasitic loss of all, but require drastic changes to the exhaust and intake plumbing in the engine bay, are more difficult to tune because of differing boost response under different conditions, and will make the most power out of all 3 setups.

it just depends what you want out of the car. off the line snap, you get a positive displacement (roots or twin screw). for boosted (no pun intended) performance through the whole rev range, get a centrifugal. if you want max power and can deal with just a little lag, go with a turbo. turbos also, if you can keep your foot out of the gas, won't change your gas mileage all that much, because you'll drive around in vacuum, rather than at 2-3 psi.

chriswtx

iTrader: (5)

I had the magnacharger on my car. It was nice and ran fast, 520rwhp. I was running 10psi of boost on the stock motor with just a cam(224/224 115LSA) and headers. Traped 122-123mph in the quater mile. I then switched to a Paxton Novi 2000. I changed nothing else on the car but the blowers. AFR and timing were set the same. Still running the same 10psi. I picked up 100rwhp and 7mph in the quater mile. Traps were 130mph...

Like others have said, heat soat is a huge problem with any roots or screw blower with the air to water intercooler setups and they really fall off above 5000rpm....

2000 Tran Zam

iTrader: (2)

Well one of the biggest issues with Roots style blowers is they get maxed out fast. You can maybe run 500-550rwhp on a maggie or whipple I believe, and then you have to go with a twin screw or something with more positive displacement to make more power (hence Bob's comment on them running out of steam at 5krpms).

Another issue with roots style blowers is traction... It makes so much tq down low if you just spin then your kinda wasting the power. Centrifugal S/C's are more linear and allow for more controllable and expected power.

You picked up 7mph in the 1/4 cause of obviously the 100hp increase and top end pull of a centri...

Now, you throw a pair of 28 inch slicks with a 3.3 twin screw whipple and stroker motor and hold on!!!

engineermike

Each has its purpose.

I love the Eaton on my Lightning. It may make squat for power over 5000 rpm (also blame the 4.13" stroke of the 5.4), but for tip-in acceleration and trailer towing, it can't be beat.

I really liked the centrifugal (T-trim) that I had on my '95 Z. It had instant response and pulled great up top, to the tune of 10.4 @ 133 mph.

My current turbo makes the most power (146 in the quarter now), but when you hit the gas it's like stepping on the sponge. It feels like there's a big spring and damper in the throttle cable. You hit the gas and get 300 hp, then 2 seconds later the other 600 wake up.

My jet ski has a centrifugual blower, which is perfect for that application. No lag at all. The characteristic of a jet drive is that, from a dead stop, if you hit the gas, the engine goes to within 500 rpm of peak hp and stays there. If it had a roots blower (a la Ultra 250), then all the low-end response and torque would go to waste because the engine is never under a load down there.

MM&FF did a full dyno test a while back with a '03/'04 Cobra motor. They tested the stock Eaton, a Kenne Belle, a Vortech, and twin turbo's all on the same engine, all at the same 14 psi boost. The Eaton made 580 hp & 575 ftlb, the KB made 705 hp & 595 ftlb, Vortech made 725 hp & 580 ftlb (though it lost almost 300 ftlb from the Eaton down low), and turbo's made 830 hp & 755 ftlb (though it lost 200 ftlb from the Eaton down low before spoolup) all at the flywheel. That pretty much sums it up.

Mike

EPP

iTrader: (22)

Mike, that is a good comparison. Bob

gametech

iTrader: (1)

A lot of useful info has been posted here, but it does lack one mention. Twinscrew s/c's can be had in a side mount configuration that allows for a REAL intercooler, as opposed to the commonly available manifold mounted a/w heatsoaks. This is a VERY underutilized approach that is almost impossible to fit on an F-body, but does merit mention in general boosting terms.

jaydubb

You are NOT lying sir!

My GTP can MAYBE make 2 runs back-to-back before its DONE and needs a cool-down. And yeah, its great down low but it falls WAY OFF above 5000 rpm.

DeltaT

iTrader: (5)

It merits discussion in a theoretical sense, but talk about underutilized - I've never seen a car set up that way, and unless you had an old truck or something with a huge engine compartment, you would have a very hard time shoehorning in a unit big enough to warrant the trouble on a 350ci.+ V8.

Jim

engineermike

It wasn't a v-8, but the Ford Thunderbird supercoupe's had a Eaton roots blown 3.8 with an air/air intercooler plumbed up.

kp

iTrader: (34)

I just seen some pics of a sidemount twin screw on a C6, cant find it now. Plug changes looked to be a challenge but overall a pretty clean setup and you can use the stock hood.

DeltaT

iTrader: (5)

If you ever dig them up I'd like to see them.

How did it look from a heat soak perspective?

Jim

kp

iTrader: (34)

Uses a FMIC I believe, not sure who's kit it was but I think its a production or soon to be produced kit. If it has some kind of intercooler then heat would really be no worse then a turbo mounted in the same spot.

gametech

iTrader: (1)

Sweet, I'm glad to see this isn't as underutilized as I thought. BTW, not everyone has the insanely cramped engine compartment of an f-body.

mahhddgtp

That is crazy...

Why are you no longer a mod? (or at least green)