bridged exhaust port problems

[bluehawkkevin]

thanks guys, my evo is running fine now...just that there is a rpm drop when it reaches top end....(after increasing the exhaust port by 1mm)...why does it happen??

 

[Big B NRG]

Do you drive an overrange?

 

[tiba_karotsu]

thanks guys, my evo is running fine now...just that there is a rpm drop when it reaches top end....(after increasing the exhaust port by 1mm)...why does it happen??

increased the exhaust port by 1mm? by that do you mean you raised the inside of the exhaust port by 1mm or you made the outlet larger by 1mm?

that just goes to show you porting isn't something anybody can do, you may just have ruined a perfectly good cilinder.

bigger isn't always better when it comes to exhaust port size.

 

[47lamy]

I know its a bit late but for reference, this is what i worked with when drilling pistons on mhr and hebo cylinder kits.
http://www.wiseco.com/PDFs/Manuals/MSeries.pdf

 

[bluehawkkevin]

i made it higher at the sides of the butterfly by almost 1 mm , which makes the burnt gases exit at an earlier stage while new air/gas coming in, it resulted to a "fine" and torquey response ,i changed the plug and adjusted some plug height , my rpm drop was already OK , some pulley problems , i have already coorectedthe puley angle , now it reaches 115kmh with full body of my malguti firefox..its almost 2 weeks now...thanks 47lamy for the idea..

 

[manic]

wow... sounds scary!