190 cc briggs engines

[james1950]

i have always wondered how briggs gets all the different horse power and or torque ratings out of there 190cc engines.i have seen ratings of 6 hp.,6.5 6.75 and 7.25.
how do they accomplish this?the only thing i could think of would be the size of the valves.

 

[MolaKule]

Valve timing and overlap, valve and ignition Timing, and fuel metering as well.

I don't know if different size valves are used or not.

Maybe a small engine mechanic can chime in.

I know my my Poulan mower has the 190cc with about 6 Hp. Great engine, never a problem.

BTW, have you seen the dipsticks of late? They specify an oil volume of 591 mL or 20 ounces. I found that anything over 570 mL will make them smoke.

 

[Propflux01]

Camshaft

 

[MolaKule]

Originally Posted By: Propflux01
Camshaft


As in lift and duration?

 

[spasm3]

Same thing on my Kawasaki 21hp toro engine, the 24hp engine specs the same cam valve and carb part numbers but in don't know how the hp is different.

 

[Quest]

all of the above.

@OP: do remember that these are very simple executed OPE engines, other than compression release, there's no sophisicated cam profiles, VVT, etc. and a simple 1 valve per intake/exhaust setup. So the torque curve (peak) is a simple, if not traditional type where there's a predefined output (horsepower) peak and also a separate torque peak.

While I cannot tell you exactly where the torque peak on these OPE engine lies, one thing for certain though: because these are general application engines (OPE engines on power washer, all sizes mowers, etc.) for certain types of execution your OPE engine may not be running at it's peak (peak torque or peak output)...but just below or slightly above it.

At the end: these so-called torque figures published by OPE engine manufacturers is "moot" and it's really up to the consumer to find out if such engine has been "optimized" for the application to get max. efficiency given the application.

My 2'cs worth.

Q.

 

[wag123]

1 part carburetion and 1 part deception.
This started 20 years ago with the B&S Quantum engines, they were sold with HP ratings of between 4hp and 5.5hp, all with the same displacement. The only difference between them that I could discern were that they had different carburetor part numbers.
In the old days, the higher the HP, the larger the displacement.
I can see why B&S did this, because there is something called economy of scale. If a manufacturer makes more of an item, the per item production cost comes down. In other words, it is more costly to produce 4 different displacement engines for 4 different HP ratings than it is to produce all the of same engine displacement and derate the lower HP ones.
Among other things, this kind of deception is the likely reason that the FTC has made the manufacturers stop advertising HP.

 

[Hootbro]

http://www.jsonline.com/business/85489322.html

 

[wag123]

Originally Posted By: Hootbro
http://www.jsonline.com/business/85489322.html

The only people who are going to get anything meaningful out of that deal are the lawyers!
Also, I don't think that the buyers who purchased mowers with the 5.5hp Quantum got a bad deal, it's the other way around, the people that purchased mowers with the 4hp Quantum got more than they paid for.

 

[edhackett]

It's usually the carb. I know that when looking at 4-6 hp outboard motors, they are the same except for the size of the venturi (restrictor plate) in the carb.

Ed

 

[Hootbro]

Originally Posted By: wag123

The only people who are going to get anything meaningful out of that deal are the lawyers!
Also, I don't think that the buyers who purchased mowers with the 5.5hp Quantum got a bad deal, it's the other way around, the people that purchased mowers with the 4hp Quantum got more than they paid for.


Point being to the OP's original question, the reason they got all those different horsepower ratings was mainly because they made it up.

Briggs and all the other small engine makers here in the states to include Kohler, Kawasaki, Tecumseh and a few others, colluded through their self made trade association to underrate many of their engines with phony HP claims.

 

[KD0AXS]

My MIL has a "15.5 HP" Tecumseh powered MTD rider that she bought new from Sam's Club in 1998. She sent in all the required information for that class action lawsuit. I think it took nearly a year, but she did indeed get her check for $75.

 

[bvance554]

I think its a shame that we are so lawsuit happy that someone decided to sue because they thought their 6hp mower was only making 5.5hp. Sure the way they were marketing the hp ratings was wrong but we needed to sue over it?

 

[supton]

Would the manufacturer stopped their practice otherwise? Do you buy Consumer Reports (or anything similar), so as to support independent testing of the motors, so as to find the true hp?

I'm not crazy about lawsuits either, but they serve a purpose.

 

[Propflux01]

Originally Posted By: MolaKule
Originally Posted By: Propflux01
Camshaft


As in lift and duration?


As I understand it, in the older engines, before 1990ish, the differences between the 3.5hp and 5hp is the camshaft. I know later engines had a change in bore and stroke for the 5 and 6.5 hp engines

 

[Quest]

Originally Posted By: supton
Would the manufacturer stopped their practice otherwise? Do you buy Consumer Reports (or anything similar), so as to support independent testing of the motors, so as to find the true hp?

I'm not crazy about lawsuits either, but they serve a purpose.


While I'm not particularly happy about the FTC ruling and the "workaround" tricks that OPE manufacturers resort to branding their output afterwards, I seem to recall back in the slightly earlier days where there's specifications available (to those who needs it) RE: what output figure @ particular RPM provided. Not sure where to look for that info anymore RE: B&S.

Q.

 

[TFB1]

Originally Posted By: Propflux01
Originally Posted By: MolaKule
Originally Posted By: Propflux01
Camshaft


As in lift and duration?


As I understand it, in the older engines, before 1990ish, the differences between the 3.5hp and 5hp is the camshaft. I know later engines had a change in bore and stroke for the 5 and 6.5 hp engines


The difference in a 1980s 3.5Hp & 4Hp is approx 2cu in, the 3.5 is 9.02cu in while the 4Hp was 11.4cu in... Yeah they also listed a cc but I don't do those...

 

[KD0AXS]

Originally Posted By: bvance554
I think its a shame that we are so lawsuit happy that someone decided to sue because they thought their 6hp mower was only making 5.5hp. Sure the way they were marketing the hp ratings was wrong but we needed to sue over it?


When a company is deliberately misleading and ripping off consumers, I'm all for suing them.

Suing because you spilled hot coffee on your own lap....not so much.

 

[Cujet]

Interestingly,

Many years ago, Mercury outboard engines were available in different HP ratings. But the core engine was exactly the same.

They "adjusted" output with ignition timing changes, RPM ratings, and sometimes, carb size. But, the main change was the timing.

 

[Nick R]

Here is two different graphs, from Briggs & Strattons website. You can find out the horsepower rating at each rpm using the Torque x RPM ÷ 5252 formula. The engine torque rating is at 2600RPM, the Horsepower ratings are at 3600RPM.

7.25lb/ft torque curve
http://bsintek.basco.com/BriggsDocumentDisplay/jkqqsNDvrS8lFix2.pdf

6.75lb/ft torque curve
http://bsintek.basco.com/BriggsDocumentDisplay/jkqssNDvrS8lFix2.pdf


For reference, here is the 875 OHV
http://bsintek.basco.com/BriggsDocumentDisplay/jkqnsNDvrS8lFix2.pdf

and the new 550 OHV curve.
http://bsintek.basco.com/BriggsDocumentDisplay/jirpsNDvrS8lFix2.pdf