Turbocharging a lawn mower

[bertsmobile1]

The phrase silk purse from a sows ear comes to mind
It is not as simple as just bolting on a kit
You would need a steel con rod , more or larger head bolts , modified governor , new crankshaft dynamically balanced + the kit costs which even without labour would be more expensive than a bigger engine.
Next you will not double Hp unless you double revs and if you try running it at 7000 rpm then little end will depart the can rod if the crankcase does not explode first .
After that increased engine speed will change the airflow dynamics under the deck so it might not cut the grass at all.
I have done some racing engines and these came to well over $ 1000 just in parts and for that there was no doubling of Hp .
The muffler does not "take away" Hp but tuning the exhaust will help breathing and more efficient cylinder filling over a specific narrow range of engine revs .
Adding weight can help prevent bogging down
A lot of old 30" to 40" ride ons were fitted with small 8 Hp engines but they had very heavy cast iron pulleys to store momentum

Who ever has been feeding you this guff has spent too many hours on Face Book & You Tube .

 

[wineman]

A single cylinder governed engine running 3400 rpm would respond to a positive displacement supercharger but you won't get enough exhaust to properly spin a turbo to get any midrange improvement. You need at least a twin cylinder engine for a turbo to work. The kits in your link are for multi cylinder 500cc or bigger engines. Trying to turbocharge a push mower would be very difficult and probably cheaper to just buy a mower with a bigger engine.

I see, however the person that referred me to this procedure, showed me a video that moved the running rpm's to 6000 and had an addition that allowed more air flow. Does that make any sense?

Thanks

 

[wineman]

The phrase silk purse from a sows ear comes to mind
It is not as simple as just bolting on a kit
You would need a steel con rod , more or larger head bolts , modified governor , new crankshaft dynamically balanced + the kit costs which even without labour would be more expensive than a bigger engine.
Next you will not double Hp unless you double revs and if you try running it at 7000 rpm then little end will depart the can rod if the crankcase does not explode first .
After that increased engine speed will change the airflow dynamics under the deck so it might not cut the grass at all.
I have done some racing engines and these came to well over $ 1000 just in parts and for that there was no doubling of Hp .
The muffler does not "take away" Hp but tuning the exhaust will help breathing and more efficient cylinder filling over a specific narrow range of engine revs .
Adding weight can help prevent bogging down
A lot of old 30" to 40" ride ons were fitted with small 8 Hp engines but they had very heavy cast iron pulleys to store momentum

Who ever has been feeding you this guff has spent too many hours on Face Book & You Tube .

I had asked about some of what you said,but the people indicated there will be no such problem. They also said the current head-bolts should hold with no problem. I was concerned if it would cause engine failure and they indicated to put in differential oil and that would solve the problem.

Thanks

 

[Hammermechanicman]

You are talking about a single cylinder push mower engine which is probably 8 to 10 cubic inch displacement. Here are some reasons why turbocharging such an engine is difficult. First is exhaust reversion. When a single cylinder engine closes the exhaust valve the exhaust gases literally stop until the exhaust valve opens again and gasses are pushed out. This cycle of pressure and no pressure is called exhaust reversion. Not what you want to spin a turbo. Second reason is exhaust gas volume. Turbos need to spin at least 3k to 4k to start to build boost. Look at the size of a turbo on a 2.5L (150CID) car engine and now scale it down to a 8 CID engine governed at 3400 RPM. It will be a pretty small turbo. Next is the carb. Trying to pressurize a simple push mower carb to deal with varying degrees of vacum and boost and properly meter fuel at different loads and RPM would be a nightmare. Cooling would be an issue since the engine is designed to cool at a certain power output. More power equals more heat.

I would like to see a working turbocharged push mower from the folks you are talking to.

Different oil fixes a problem??????

 

[Hammermechanicman]

I see, however the person that referred me to this procedure, showed me a video that moved the running rpm's to 6000 and had an addition that allowed more air flow. Does that make any sense?

Thanks

Are you planning to run the engine at 6000 RPM?

 

[bertsmobile1]

It is your engine and your money so go piss it up against the wall as you seem to be determined to do that
You have just had 2 techs tell you it will not work and you run the risk of destroying your engine if by some miracle it does work
Very few mower engines will run over 5000 rpm for any length of time
The con rod is simply not strong enough
When the governor fails usually the piston ends up slamming into the head because the rod fails
These engines are a cheap as it is possible to make them
Then there is the balance factor , they are not balanced to 6000 rpm
When I do a racing engine they have to be dynamically balanced, particularly the flywheels
I can make a mower engine do 10,000 rpm if I want to, but it won't do that for any length of time

Then as previously mentioned you have airflow under the deck to consider
In many cases over speeding the engine will cause either the grass to build up under the deck till it chokes the mower or will toss rocks 60' out the chute or right through the side of the deck
Just increasing the speed from 3200 to 3600 on a Honda buggered the deck within a single season .
Next striking an object ( tree root for instance ) at double the revs will probably bend the crankshaft like a bannana
And on top of that there is blade balance to take into account
The faster the blade spins the higher the level off balance needed .

This is my last word on this thread
No use talking if the other party refuses to listen
and note neither Hammer nor I make a cent for giving you sound advice where as the other clot is trying to sell you a trick up kit that will not work .

 

[CraigH]

I'm curious, how much have you been quoted for the turbo and related parts to convert the engine you have?
And have the people who have been giving you advice on this actually shown you a running single cylinder mower engine with their turbo kit on it?

 

[wineman]

I'm curious, how much have you been quoted for the turbo and related parts to convert the engine you have?
And have the people who have been giving you advice on this actually shown you a running single cylinder mower engine with their turbo kit on it?

Yes and I can get is done for $75.

 

[wineman]

It is your engine and your money so go piss it up against the wall as you seem to be determined to do that
You have just had 2 techs tell you it will not work and you run the risk of destroying your engine if by some miracle it does work
Very few mower engines will run over 5000 rpm for any length of time
The con rod is simply not strong enough
When the governor fails usually the piston ends up slamming into the head because the rod fails
These engines are a cheap as it is possible to make them
Then there is the balance factor , they are not balanced to 6000 rpm
When I do a racing engine they have to be dynamically balanced, particularly the flywheels
I can make a mower engine do 10,000 rpm if I want to, but it won't do that for any length of time

Then as previously mentioned you have airflow under the deck to consider
In many cases over speeding the engine will cause either the grass to build up under the deck till it chokes the mower or will toss rocks 60' out the chute or right through the side of the deck
Just increasing the speed from 3200 to 3600 on a Honda buggered the deck within a single season .
Next striking an object ( tree root for instance ) at double the revs will probably bend the crankshaft like a bannana
And on top of that there is blade balance to take into account
The faster the blade spins the higher the level off balance needed .

This is my last word on this thread
No use talking if the other party refuses to listen
and note neither Hammer nor I make a cent for giving you sound advice where as the other clot is trying to sell you a trick up kit that will not work .

Thanks for your help. I have bought one of the kits and will let you know what happens to the mower.It is fairly new, so it should tolerate more power.

 

[Hammermechanicman]

Yes and I can get is done for $75.

Link to kit? I am curious.