So I have read a few threads over the years where people say it takes X amount of HP to spin a blower. Some of these claims are in the hundreds. So any one with some real world testing care to chime in and talk about their experience or research.

So I have this retarded idea for a procharger and these high HP killing claims would shut this down quick, here goes...

So if you were to take a 20hp Briggs and Stratton engine mount a pulley combo to the bolwer and engine to max out lets say a F1-A. Put this on a skid and place it in the bed of a pick up truck, and use a turbo waste gate to control the amout of boost the truck engine is getting fed. So the briggs engine would only be spinning the blower, nothing else. Could the 20 HP motor do it or would the blower bog it down to the point it would either die or couldn't get up to its max RPM's ??? This is the type of engine I'm talking about. https://www.google.com/shopping/prod...ed=0CEEQ8wIwCQ

Your thoughts please.

 

I dont see a 20 HP motor spinning an F1A to any reasonable RPM.

A quick example of the power needed to spin these things would be where ProCharger says you need a minimum of 900 HP from your motor to work effectively with the F4 blower.

If you want some cool stuff happening in the bed of the truck, build a turbo system blowing into the bed, let the turbos sit out and breathe fresh air, and amaze passerbys on the highway

 

^^^what he said.

 

How high you want to rev this Briggs haha

 

i remember a few years ago I read (forgot the #'s) it took a lot of HP to spin a top fuel blower

 

Top Fuel blower takes about 600 hp to produce about 50 lbs at the starting line and 65 lbs at the finish. They would like more if they could get it.

 

This is like the theoretical discussion when people say turbo's are 'free' power. They aren't really because they cause exhaust backpressure, which reduces the power that you'd get if you had free flowing exhaust.

Fact is, if you're concerned about the power it takes to turn a blower, go bigger cubes, to help aid in the production of the power needed to turn the blower.

 

It depends, the boost you are trying to achieve will dictate the power consumption of the blower. 20HP ain't going to cut it, try more like 75HP for a street car.

 

When I had an 01 Lightning I was a active member at NLOC.net. The talked about rumor there was that it took about 100hp to spin the eaton blower hard enough to make about 14lbs @ redline on that truck. Not sure if it was factual or just hearsay.

 

If you want the real deal on how much power a turbo consumes you gotta study a little thermodynamics. The following link gives an example problem of how to calculate the energy required to take air at one temp/pressure and convert it to another temp and pressure. Basically the power is dependent on how much of a pressure change you want and how efficient your turbo charger is. Hence when you try to size a turbo for your engine you use compressor maps to find one that is in a good efficiency range so you can get the most boost for the least amount of power input. If you really wanna know the power and don't wanna do the calculation you could get any 3rd year mechanical engineering college student to do the math for a case of beer.

http://www.mne.psu.edu/cimbala/learn...nergy/home.htm

Example Problem:

Given: An air compressor

 

Thanks for all the responses guys, good input. I never would have thought it would take that much power to turn one of these things to 65,000 - 70,000+ rpms. We use a few pieces of equipment at my job that run on these Briggs engines and they are little work horses for what they are. I also had thought about the room to work with would allow the use of something like a 15" crank pulley and a 8" blower pulley would make it easier to spin the blower.

So let me throw this out there because this seem to be the general thought...

You take a engine the makes 500 N/A hp on a engine dyno. Bolt on a F1-A blower pullied to the max and just let it blow all its air in to the atmosphere. That same 500 hp engine would be making around 400 hp ???

 

http://not2fast.com/turbo/maps/ - has work required to spin Eaton S/C's as a function of blower RPM.

From the Turbo FAQ stickied in this section...not being an a-hole, was browsing through it earlier today.

Engine horsepower is a function of air flow through the engine. Air flow is also a function of blower RPM. Use the air flow chart to determine what RPM you need to run the blower at to achieve your engine power level. Then use the RPM from the flow chart to determine how much additional horsepower is consumed by the blower.

 

Exactly. You're taking power from the engine and making it compress the air. Since you're not placing the compressed air into the car, you'll measure less HP from the engine instead of more.

Let's change your example up some. Instead of an F1-A, let's choose an accessory. What if you disconnected the hydraulic hoses from your power steering pump and the PS fluid sprays into a bucket instead (we're pumping PS fluid instead of air). Would to expect to measure the same HP as when the fluid was being run through the PS pump, or would it go up (assuming pump had same amount of backpressure)?

Or put differently: would you expect more HP from an engine if you removed the power steering system (or A/C, or alternator, etc.)? All of those systems perform work using the engine's power too.

 

Morris did some testing on this and posted the results over on the bullet. It was in the hundreds.

 

THIS ^^^


Steve Morris determined it takes 250hp to run an F1R blower restricted to 23 psi at max impeller speed (68k)...

I can tell you that spinning the F1R by hand takes a good bit of effort and it feels like a meat grinder as it spins...

 

Great idea but you would need a pretty powerful engine to turn the blower fast enough. It will be dependent on the volume of air and pressure you require and will rapidly vary as you open the throttle. That's the advantage of having the blower attached to the engine.

For the ultimate solution, you need to run a turbine with a bypass on the compressor to bleed air for the engine. This has been done on a hilclimmb car in the UK many years ago.

http://raceenginedesign.biz/Manic-Beattie.htm

They basically built a 4 cylinder version of the Napier Nomad engine (see below link)

http://en.wikipedia.org/wiki/Napier_Nomad
The problem they had was keeping the turbine alight during low throttle opening (engine not producing enough exhaust gas volumes) and i believe when going WOT (engine requiring large amounts of air but again low exhaust volumes). This obviously isn't an issue for a areo engine as they sit a constant power for prolonged periods.

The other solution is to use the tried and tested turbo but get them working a little sooner.

Subaru, and probably others, have the best solution in the forms of their 'Rocket box'. This basically turn your turbo(s) into mini jet engines (similar to the Nomad but with more focus on the engine). So in a normal turbo setup Subaru mounted a bypass in the intake to a combustion can . In here fuel and air are mixed and burnt. The resulting exhaust gasses are then mixed with the engine exhaust volume and that drive the turbos turbine. By varying the amount of air bypassed and the amount of fuel added you can can basically run the turbine shaft speed at whatever you want independent of the engines RPM or throttle position! Roll on 2bar of boost at launch and ZERO lag.

Also this system was MUCH softer on the turbos and exhaust components that the old bang bang version of anti-lag (retarding of the ignition timing so the combustion event is happening while the exhaust valve is open/opening) as also easier to 'throttle'.

 

Thanks for all the input and links guys... Never would have thought it takes any where between 100 - 600 hp to drive a blower (depending on the size).

 

My guess is that's why turbos generally make more power than superchargers at the same boost level.

 

Yes turbo makes more power per pound of boost. But that mad torque with a roots type blower is awesome.

 

True, Good point ^^^
I'm still shocked at what a load they put on an engine. Guess I need to try to spin a big boy blower with my hand VS my little D1