I have what may be a silly question but that never stopped me. Why are turbos so much more popular than blowers? I'm building a 292 with 4-71 blower and 3 Rochester 2 barrels for my 53 chevy 1/2 ton pickup. When I go to car shows it seems that turbos rule and just the occasional roots blower engine. To me it seems like a blower is so much simpler. If I want to change my boost I just change the pulley and ignition program. I also don't understand how a restriction in the exhaust is helpful. Also if you are running duel exhaust does it just restrict one bank? It's true that I like the "chicks dig it" look of the roots blower but I'm just trying to learn. Thank you for your time.

Turbos are really pretty much Free HP And in some cases (cars) not much room up front for the bigger belt drives.
Just some 2cent comments

I agree. Crank driven blowers take crank HP to run them. Turbos mostly use power that is escaping out the exhaust. In our engines a very large percentage of the energy created by the combustion of fuel is heat that is wasted and causes over heating and exhaust gas issues. Turbos use some of it to make power while crank driven blowers add to it. On inline engines the turbo manifolds mount the turbo close to the engine and have a single outlet. If you want duals you could split the pipe after the turbo. That said a 4-71 or a McCulloch on a Jimmy is a cool thing and works very well.

If you don't think turbochargers rob horsepower, disconnect the intake side and run the engine, normally aspirated, with the turbo still mounted to the exhaust!! I've done it!! It really kills some engines' performance. Further, apply restriction equal to manifold pressure to the open system!!

Turbocharged horsepower is NOT something for nothing!! Turbocharging has it's own peculiarities and drawbacks.

I'm a fan of both!!

A side note: Most production automobile engines don't have enough power to drive the supercharger on a top fuel engine!!!

A second side note: Most production engines won't make enough exhaust thrust to drive a high output turbo like the ones seen on top sportsman race cars!!

Turbo are cheap and easy to get. Roots blowers not so much. Centrifugal SCs are, comparatively, way expensive. It is easier to make or get a turbo exhaust, than a roots type blower intake manifold. Even if using dual exhaust, it needs to be Y'd into 1 to mate with the turbo flange (see Power Nation's turbo 292 build). Blowers are parasitic. If designed correctly, turbos present minimal back pressure and as Larry pointed out, that makes the available waste product of inefficient internal combustion available to be reused for more HP...a lot more.

I have a manifold for a 3/4-71 for my engines but the cost of just blower, I have found is more than the parts for my entire turbo setup.

If you compare apples to a different kind of apples...the intake charge will need to be cooled (or not) for both. If not, and you use draw-thru with a turbo, it's even cheaper to implement (no intercooler). If so, you'll need a water/meth injection for both or you can use an intercooler for the turbo setup. Again, cheaper.


I personally would love nothing more then putting a 4-71 on one of my cars. Having a blower sticking out where a blower doesn't belong. That distinct whine and sucking of air.

Sigh...anyone have an extra roots blower :-)

Regards,
RJ

I understand the space thing. I didn't realize that turbos were less money. Here's how mine adds up. I think the blower and associated hardware snout and all about $3800. 3 Rochester 2 bbl chrome carbs set up for blower $2000. Custom 12 port intake manifold with meth $4500. Custom stainless tuned headers for 12 port $2500. Probably another $1000 in other stuff. The tests that i've seen show a 40-70 degree temp drop in charged air with carbs vs injection.

For the Power Nation 292 build which included engine rebuild and new parts. The whole build was probably in the area of $3000?! They got ~400HP and 500+tq. To get a JY turbo setup from a Pontiac 301 and DIY the rest is a few hundred, ~$1200 if you add JY TBI and Megasquirt EFI.

If you just look at the number of 4-71 blowers or roots blowers general availability vs the aftermarket or used 5L turbos there is no comparison.

Turbos vs SCs also apply power differently. Leo even mentions (more than once), the turbo advantage, in his book. When designed correctly, a turbo is a great companion to augment the GM inlines' capabilities.

Regards,
RJ

That's quite a difference. I know i'm not normal. I have been saving for 30 years and put off my retirement to build my 53 that I bought in 1980. On race fuel I have been told to expect 800 hp and about the same in torque. We'll see. I'm limited to 800 without dowelling the mains according to Mike Kirby. I know of 3 guys running 1000 hp, 2 turbo and 1 blower.

Do you have knock retard on boost?

Yes I'm running Electromotive TECs200 direct fire ignition. It has knock sensors and adjust accordingly from what I understand.

This is a quality product AFAIK. It may have both programmable retard (connected to manifold pressure) and also "listen" for a specific noise frequency to automatically detect knock (it ignores valve train, cam drive rattle, piston slap, etc. but recognizes destructive pressure in the cylinder). The actual frequency is related to bore size IIRC?

Found it.
Knock Frequency = 900,000 ÷ (Pi × .5 × cylinder bore diameter in millimeters) which equates to roughly Knock Frequency= 573,000 ÷ (bore diameter in millimeters).
https://www.phormula.com/KnockCalculator.aspx

I don't know a lot about this stuff. I build dry ice manufacturing plants. I depend on experts that come recommended by experts much like I do with my plants. I have been told that Electromotive is one of the best and it will do all I need or want and more. It will store 200 engine management programs. It has multiple stages of rev limiters and I think you can set timing by individual cylinders. I have no idea why you would want to do that. I'm really looking forward to learning about this new fangled stuff. The whole thing is about the size of my cell phone. I have been working on my project for 3 years now and I'm close to actually starting on the truck.

Get us some photo's and video when you get to that point.