Inliners International Forums General Discussion Bench racing Blower vs Turbo

Folks, I know there is a turbo/blower forum, but my question is more hypothetical.
A supercharger such as a roots blower from my understanding increases power evenly over the rpm , that is if you gain %20 at 100rpm you will gain %20 at 5000rpm.
Whereas a turbo has a non linear gain maybe %5 at 1000rpm & %30 at 5000rpm.
So my question is why use a turbo for street use when most people would not use high revs during daily driving? My tacho sits at approx 2000rpm & rarely more.
Is it because at those low rev's no one wants power ,so less fuel is consumed in everyday driving, but when you want go, it is there? My thoughts would be to use a blower allowing more low down grunt & higher gearing.Your thoughts would be appreciated.

With out a lot of tinkering you can cool the compressed turbo air but not the blower air i live in sweltering heat of az thats how i made my choice i think both are great!

Even with an intercooler, the incoming air in a turbo will never be cooler than with a blower. Also, the higher the RPM, the hotter the air charge will become in a turbo because the outgoing exhaust heat raises proportionally with the increase in power its making, but not with a blower because the incoming air is fixed at whatever the outside air temp is. A turbos incoming air temp can change several hundred degrees while a blower may only change 5 or so degrees. Even if the outside air is 100°, the incoming air in a turbo will not be cooler than that when its under power.
There are trade-off's to both types, usually money vs. ease of installation, and turbos are cheap while blowers are more expensive typically and take up more engine compartment room.

When I data log my Syclone, the incoming (M.A.T.) air does not get a lot hotter then the ambient temperature, this is when a steady state cruise. Maybe 10 degree's hotter
I think the hottest I ever seen my manifold air temp go to is 150 degrees on a 100 degree day at 21 PSI.
Still using the stock air to water intercooler.

Now, w/methanol injection single nozzle injection installed I can boost to 25-26 PSI & manifold air temp will go down to 55 degree's F up to 65 degree's on a 70-80 degree day.

I love methanol. It is a super chiller.

MBHD

I can comment about my friends old 162 CI B&M blower (SBC 400), that thing would make the intake manifold smoking hot & also the Blowers case would be smoking hot & just cruising around boost would only get up to 6-8 psi tops. You could not touch the blower case w/out burning yourself.

He blew up his engine (it was fast while it lasted), let another friend borrow the blower, quickly blew that SBC 350, you just can't run 87 octane & go for W.O.T. blast & expect a engine to take it w/out a proper tune w/a blower, or a turbo for that matter.

I think w/the newer blowers that have a bypass valve, that should keep the blower cooler when just cruising around.

MBHD

Where would a McCulloch supercharger fit into this discuaaion? Hank I remember the setup you built with all the amazing brackets and pulleys.

There have been huge leaps in advancement with centrifugal superchargers since the original McCullough's. I would choose a ProCharger or Vortech over a Roots blower style any day. The plumbing for one of those is similar to a turbo, and can be tucked into most any engine compartment pretty neatly.

Much of the improvement used in the "modern" centrifugal superchargers was stolen from a friend of mine who sent his new impeller design and new ball drive improvements to one of those companies for them to "look" at. They just copied it. He has done some more work that they don't have and he can do it all to the old McCullochs. The one in my son's Stude was a prototype. The problem is to get him to do it. He is the busiest man I know, and I know a few over achievers.

This old set-up?







The Paxton did not seem to get as hot but it does get pretty warm.
I had an external oil pump & cooler, so that helped a bunch w/temps.
Problem w/the old ball drive system is that they would slip & I could never get the higher boost I was hoping for.
That is why I sold it.

MBHD

That's the one! That is cool, well maybe not really cool but I bet it wasn't smoking after a cruse.

It was fun while I used it but only made good power in the upper RPMs 3500-7000.
I made these pulleys
the smallest one was made just so it would boost down low, but I had to limit the engine RPM to 4000 RPM, anymore than that, it would over spin the blowers max RPM Of (IIRC 42,000RPM) which I did one time (forgot I had the smallest pulley installed @ the time ), then I sent it to Paxton for a rebuild of about $500.
I later sold the blower & brackets to a guy in Australia through Ebay.

My car was really more enjoyable to drive & had tons of low end grunt when I had 12:0 compression & 3, 48 MM Weber DCOE's

With the Paxton blowing through the same 48 MM DCOE's, it made a bunch more top end power, but the low end suffered because the Paxton could not produce enough boost down low & was limited by being only able to spin to 42,000 RPM.

With todays blowers, they can produce too much boost if need be.
One thing nice about the planetary ball drive Paxtons & early McCulloch blowers is that they were super quiet as compared to todays gear driven compressor wheels, (you can hear most all the newer style blowers even @ idle, my Paxton, you could not hear it @ idle.

The Paxton combo was enough to get my Camaro to run low to mid 12 second 1/4 mile times.

The 12:0 engine w/3 48 MM DCOE's was good for 13 second times & when I ran a single Carter AFB 400 CFM Cliffold intake & headers 10:1 4 speed w/4:10 gears was good for 14.30's.
All w/a 250 CI inline Chevy inline 6 .

The lightest I ever got my Camaro to weigh was 3000 LBS, normally it weighed approx 3300-3400 LBS

I miss driving my Camaro, one day though, watch out

MBHD

Here was the external Paxton pump & oil cooler.




8 " crank pulley


MBHD

Anyone adapted current GM superchargers off their v6"s?

Has anyone ever used a current GM supercharger, off their v6's? These should be relatively cheap & about right size for inliners.

There are a couple guys here that has installed those blowers.
They are a bit small but will work.

MBHD

Anytime you compress air the temp increases if you doubt this lay tour hand on your shop air compressor after it has been running for a few minutes. Anyone who has run a roots blower will tell you it heats the air.

CC,

I've got a couple M90's off GM 3.8 V6's. They are pretty long for a longitudinal engine. A shorter snout can be had, but the throttle body is mounted on the back of the blower. Getting one into most engine compartments can be a hassle. Transverse, not so much of a problem.
The Ford Thunderbird version mounts the throttle body to the side instead of axially in reference to the rotors. That version is much shorter.

One I have is a good take off, the other is a fresh rebuilt from Holley. Folks hear a rattle, and they replace the blower for a bucket of money. The problem, generally, is a ten dollar coupler.

M90's or any of the Eaton's are Blowers, not compressors. At low throttle settings, they have a bypass that allows the blower to idle, without a lot of power loss. When you put your foot in it, the bypass shuts, and you start stacking air. Typically, they don't make a ton of boost. I don't know how much you can get out of one, but single digit boost numbers are typical.

The Eaton has a self clearancing coating, which does not tolerate fuel. They are designed to run dry, not in A/F mixture. Some folks remove the coating with oven cleaner, and run them that way as a draw through. Though not as efficient, they still build some boost.

CJ