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Topic "Tuning a Kohler CH750" (Messages 1 à 7 sur 7)

Dernier message par giovanazzi85, le 21/05 à 18:02:46

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Basil

Constructeur

inscrit le 23/07/2014

le 20/01/2015 à 13:17:54

Tuning a Kohler CH750

Sorry for the english. When the Kohler CH750 is used as in Igor's kit (direct drive) are there any changes that can be made to increase the power to say 35-40hp without increasing maximun revs? Change of carburetor or camshaft?

Most of what I find on the internet is aimed at increasing the max revs permissible.

Don't want to go the reduction drive route as it would mean designing and fabricating a new engine mount which might be beyond my capabilities.

Basil

AlexR

Constructeur

inscrit le 01/05/2014

le 20/01/2015 à 18:34:15

Tuning a Kohler CH750

Hello Basil,

I think we could slightly increase the compression ratio.
Change carburetor will increase only little power. A carburetor with altitude correction will permit to retain more power in altitude. I think about the Mikuni BN34-28-8010

Alex

Message modifié le 27/01 à 18:12:32 par AlexR.

Starling

Constructeur

inscrit le 05/11/2009

le 21/01/2015 à 18:07:30

Tuning a Kohler CH750

Hello gents,
the standard CH-750 engine has compression ratio of 9,4:1. The increasing of it could bring higher level of vibration and higher loading of connecting rods, pins and bearings. Any TBO setting would be very problematic. That is reason why we do not increase it. Few ponies could be obtained performing head channels porting and intake manifold refinement but this is very laborious thus expensive operation.

Igor Spacek

Basil

Constructeur

inscrit le 23/07/2014

le 21/01/2015 à 19:32:52

Tuning a Kohler CH750

So if one wants a higher powered 4 stroke engine then the only way is a reduction drive to allow the motor to rev higher and a kohler or Briggs with a reduction drive would need a completely different engine mount.

AlexR

Constructeur

inscrit le 01/05/2014

le 21/01/2015 à 21:02:54

Tuning a Kohler CH750

Thank you Igor.

Basil: The weight will be a true problem with a reducer on the Kohler.

DanielC

Constructeur

W 44AUS
F-JUXA

inscrit le 30/11/2009

le 22/01/2015 à 10:25:23

Tuning a Kohler CH750

RPM is not an issue.
Formula 1 racers engines exceed 4000 RPM and fly at 400 km/h.
CRI CRI engines are rated 6000 RPM +

True, 4000 RPM propeller are less effcient than 3600 but by a few % (2 or 3) and reducer efficiency is around 98% and add 3 or 4 useless kg. Make your choice.

But do no dream: revolving a Kohler @ 4000 RPM will give less than 35 hp, if the torque curve is flat.

Message modifié le 22/05 à 13:51:09 par DanielC.

giovanazzi85

Constructeur

http://sd1minisport.blogs
pot.com/

inscrit le 26/04/2010