What's the minimum HP to Drive a Roots 45?

Can you drive a Roots 45 Blower with 20HP?

Thanks

yup, all the new TNTs come with 20hp Kohlers and even the LP model running propane has a slight power loss over the gas model

Ours is a 25hp which is more than enough.

This is assuming you dont run a HX

I would go 25 if can. Won't cost much more and you'll never complain about to much power. This is especially true if you work at high altitude. You can lose up to 20% hp.

I believe 20 hp is a bit on the small side for a 45, esp when you consider a 45 is rated to need 16+ hp alone, not to mention the needed hp to run the pump and anything else run off the engine. Personally I wouldn't do it, and the reason I upgraded to a 25 hp when I bought a new eng........so I would have the hp if I upgraded to a bigger blower than my 36.

Comes down to your situation. If you already have the 20 hp, go with it, it should work. If you are shopping for a motor, go with more hp for less stress.

Correction.............actually if I'm reading this correctly, then it would be over 20 hp need at normal sea level atmospheric pressure, which is 14.7 psi.....and if you were running the blower at max 3600 rpm or close to it.  

This shows 19.8 hp needed at 10psi?......So it seems the needed HP at sea level would be much higher than 20 hp?

Unless I'm reading this wrong??

Just because TM manufactures use smaller engines, doesn't necessarily mean it has the enough HP needed.............remember smaller engines are cheaper, and a lot of times they buy what they can get for the best price.

http://www.pdblowers.com/admin/uploads/urai_spec_s-12k84.pdf

Maybe why my 18hp on my TNT is only pulling 300 CFM not to mention im at high altitude

300 is adequate. Consider the carpet tool interface. Not a lot getting past there. The CFM simply increase the speed the blower can decompress the space you have given it and helps to pull the fluid back to the tank. Therefore making the hose bigger by reducing the fluid that is making the hose smaller. You can live with less CFM by keeping the wand on the carpet as much as possible. Especially during dry strokes.

Prolly, Mo.

What rpm you running it at, and what alt.?

Bigger motor just makes for less strong load on that poor ol motor = longer life.

Bigger is better ! Remember the AT&T commercial ?   

getting just under 400cfm and steady 15 lift,    lift charges up less than 1 second and that vac relief opens...   with 25 hp propane.    engine should last around 7-8000hrs,   new one is under 3k

burning 1.5gph

havent had a carpet yet with up to 250ft of hose not be dry to the touch when finishing up,    max hose run to this day is 350ft  did that with ETM and booster


soon will be getting fuel for 1.85/gal


You could get a slight larger motor but just make sure you really need it cause it will cost more when time to replace    

I would go propane if your buying a new motor,

Davey Cracker wrote:I believe 20 hp is a bit on the small side for a 45, esp when you consider a 45 is rated to need 16+ hp alone, not to mention the needed hp to run the pump and anything else run off the engine.  Personally I wouldn't do it, and the reason I upgraded to a 25 hp when I bought a new eng........so I would have the hp if I upgraded to a bigger blower than my 36.

Davey,

That's why I was asking, because you are going to come look at my blowers but I wasn't sure if you were running 20 or 25Hp.

If you are running 25Hp then no worries.

Yep 25 here.   

I remember back quite a few years the average motors that were put in TMs with
45/4Ms were 20 HP. Some even used 18HP. Remember the Hydracat that used Onan
20HP engines with Sutorbilt 4MF blowers. Also Steam Genie used the same motor with
the Roots 45. Of course both of these used propane heaters which generally have better
exhaust flow than ones using heatexhangers. By the 1990s though the engines started getting bigger. Bridgepointe by Prochem Lancer had a 22HP Kohler and Prochem built
the Prochem Bruin with the 23HP liquid cooled Kubota engine turning a 4M Sutorbilt. And the first several years of the Prochem Performer Bear used a liquid cooled Nissan
4 cylinder engine with 32HP which used the same 4MVL blower. Later they did upgrade the Prochem Perfromer and called it a 405 which used a 4L Sutorbilt that maintained 405 cfms according to them. White Magic made 3 slide ins with Roots 45 Whispair blowers. One had an 18HP Kohler another used a 20HP Kawasaki and one use a 24HP Onan . Now we do see a lot of mfgs going with 23HP and 25HP engines using 4Ms and 45 vacuum blowers. I do remember my White Magic Pro 1500 was able to run the 45 blower at the same rpms as the others running at about 2600 rpms if I remember correctly. Belt driven the 24HP Onan never slowed down at all even when running at 14Hg.
Actually though the WM Pro 1700 with the 20 HP liquid cooled engine provided more heat as it had to run at 3000 rpms turning the blower at the same rpms as the other WM models. In point of fact the sales manager for White Magic told me that the Kohler 18HP which ran the Pro 1600 provided the hottest sol. temps because they ran it really fast in order to have the same vacuum as the other 2 models using the
45 blower. So I suppose heat is another consideration when considering engine size for truckmounts . It seems nowdays that a lot of mfgs are either running their engine's direct coupled to blower or belt driving them with both engine and blower having same pulley size which of course means 1:1. The bigger engine will use more fuel but provide hotter water for TMs engineered like that.

I have an old Bates D-84 Big Red that uses a 23 horse diesel to power a 4.5 blower. No problems. It also powers the waste and pressure pump.

I can maybe shed some light on this.
My legend is a 20hp Kohler  and a sutor #4 = to 45
It takes 15.7 hp to reach 16 Hg and will give you 325 cfm. But here is the catch and why they can run it with a 20 hp or in Mo's a 18 hp
If I pull my throttle all the way my TM maxes at 3250 stock was 2600 rpms.
When my son helps me it gives me a chance to go see what the tm is doing.
My vac relief is set at 16 hg IF YOU BLOCK the hose. But to my surprise my TM on average is only hitting maybe 10-12 Hg even at higher rpms. At that Hg level it is only taking 11.8 hp to run at 12 Hg
Why? because the wand to carpet is a BIG leak and then count the cuffs ALL cuffs leak a little, then waste tank gasket, vac relief valve, hose compression, looped hose extra vac hose not needed and all over lawn. It will never come close to max lift and needed HP to turn it.
My # 4 ONLY hits high hg levels on cgd carpet and YOU CAN HEAR how much strain is THEN put on the 20 hp
If you can place your phone in front of your tm to video your gauge you will notice the same I bet.
This is why # 3 blowers do not see a big increase with 4 2 door
# 4 see a pretty good jump because the blower is building vacuum in the hose and wand slot not much but some so when you go to 42 door or 2.5 what you loose in hose is then really focused at wand slot and does give better results.
# 5+ blowers you would think the wand would be super super loud but this is not what I experienced. The wand has more noise but not like you would expect I can pull 600+ cfm but what happens is the 2.0 hose won't allow that much airflow so lift builds in hose run...higher lift = less cfm...less cfm less turbulance less NOISE.
Guys call and say..... I am pulling 800 cfm....WHAT SIZE HOSE YOU RUNNING?...I run 2.0 to a whip of 10' of 1.5 to my 1.5 wand or I run 2.0 all the way to my wand.
It is not happening more than likely the vac relief is SCREAMING with bypass air.
So yes a 20 HP will run a 45 fine would a 25 be better yes. Most certainly if you do a lot of cgd carpet were you get a very good seal to the wand.

I am talking from my own experience this is how I have come to get my answers.
Back in the day when Joe and I were close I modded my Legend and it was good but I wanted more and I wanted questions answered for myself  and to be able to answer when guys asked.
So I built a tm with twin 4's. I wanted a 5.9 but I was cleaning a repo home and low and behold a old van out back and it had a HM it
VERY damaged from freeze so I asked agent what were they doing with it " hauling to the junk yard see anything you want take it"
So I went back and bang brand new # 4 sutor cat pump but damaged from freeze so I went on a Saturday and took all I could.
My plans changed and I found a good deal on another #4 but it needed all new bearings and went from there.
Here is some action from last week