Premium members don't see ads. Click here to upgrade.

More work on the rovan 45cc

Seandonato73

Well-Known Member
Messages
1,376
Sorry kids to deal with. I did the intake boost porting on my 346xp husquvarna (read 50cc chain saw) I noticed better bottom/mid range power. Top end isnt as important on a saw. But i ran about 100 to 150* cooler on exhaust temps. I leave about a 1/8" "bridge" so the ring has something to ride on in between where groves meet above the intake. The exhaust side is kinda hard to do because of the thin cylinder design. Nessesitating the external tubes. Think of it as a modified bridge port exhaust.
 

Teejay112

Well-Known Member
Messages
309
hey if it works that's great
I do think that the faster the air goes thru the better the cooling,
and going across the head would be even better
what are the chance that you may be getting a dead spot in the corner or hot air just moving about in corner
It seems to go through the head then gets directed out right on to the header of the exhaust so far so good I think

Sent from my SM-N960F using Tapatalk
 

Seandonato73

Well-Known Member
Messages
1,376
So how are you determining horse power or torque output ? Theres no load on the engine in either of these set ups. I used to dyno the engines I built on a hydro brake dyno. Think of it as a pump hooked up to a valve the more you close the valve the harder it is for the engine to spin the pump. This is a very basic explanation if it.
http://www.foxvalleykart.com/dyno2.html
 

Z.hb71

Well-Known Member
Messages
4,519
Location
Hoffman Estates, Illinois
So how are you determining horse power or torque output ? Theres no load on the engine in either of these set ups. I used to dyno the engines I built on a hydro brake dyno. Think of it as a pump hooked up to a valve the more you close the valve the harder it is for the engine to spin the pump. This is a very basic explanation if it.
http://www.foxvalleykart.com/dyno2.html
true, was thinking about a way to make load, by doing it without load it would be as good as crank horse power. how do u suggest adding load without being extremely complicated and expensive?
 

Seandonato73

Well-Known Member
Messages
1,376
I'm trying to find a vid a watched a while ago. The guy built a brake dyno for a 5hp Briggs he was testing with a bit of modification it could be adapted to a roller set up.
 

Z.hb71

Well-Known Member
Messages
4,519
Location
Hoffman Estates, Illinois
I'm trying to find a vid a watched a while ago. The guy built a brake dyno for a 5hp Briggs he was testing with a bit of modification it could be adapted to a roller set up.
was it this guy?
cuz dude put a brake rotor on the engine and put a caliper on the rotor as u do and put some clamping force so it would put load on the engine
 

Seandonato73

Well-Known Member
Messages
1,376
Yes! That's the guy! All be it a bit rudimentary and some math would be involved to figure out the hp. In think it would be a rather economic way of making a small engine dyno.
 

Z.hb71

Well-Known Member
Messages
4,519
Location
Hoffman Estates, Illinois
Yes! That's the guy! All be it a bit rudimentary and some math would be involved to figure out the hp. In think it would be a rather economic way of making a small engine dyno.
I wouldn't mind doing sum math. I think that could work, just the rollers/roller would have to be high enough off the ground so the brake rotor don't rub.
 

Teejay112

Well-Known Member
Messages
309
Getting the exhaust welded on the weekend just run half a tank through the engine I can say with the homemade engine cover and open cylinder head airflow is so good that on the exhaust header after 20 minutes running temps are as follows

Cylinder head peaked at 90°
Alloy isolator 45°
Exhaust header 50°

Huge difference from stock
I also increased intake duration by cutting 1.5mm from the intake side of the piston that allowed me to tune leaner and also still get enough fuel when accelerating without bogging down


Sent from my SM-N960F using Tapatalk
 

Teejay112

Well-Known Member
Messages
309
Finished engine here is all the info on it
Rovan 45cc

Increased intake timing took 2mm off piston skirt

Ramped the exhaust side of the piston more angled and more taken off than the esp piston

Internally widened the exhaust port

Homemade alloy engine cover wrapped in carbon fibre
Better cooling by alot

Cut and meshed the pullstar

Port matched exhaust header

Removed the choke from the carb

Not much but enough to almost double the power from the engine in its stock form this engine is a powerful beast now and it revs like a 30.5cc


Sent from my SM-N960F using Tapatalk
 

Z.hb71

Well-Known Member
Messages
4,519
Location
Hoffman Estates, Illinois
Finished engine here is all the info on it
Rovan 45cc

Increased intake timing took 2mm off piston skirt

Ramped the exhaust side of the piston more angled and more taken off than the esp piston

Internally widened the exhaust port

Homemade alloy engine cover wrapped in carbon fibre
Better cooling by alot

Cut and meshed the pullstar

Port matched exhaust header

Removed the choke from the carb

Not much but enough to almost double the power from the engine in its stock form this engine is a powerful beast now and it revs like a 30.5cc


Sent from my SM-N960F using Tapatalk
Great work teejay!
 
Premium members don't see ads. Click here to upgrade.
Top