hey guys,
I have a question about a ported engine. When Ger ported my engine, he told me to expect a 15+ HP gain. It really did show, because after the porting the engine really opened up. But what my question is, When you port an engine the compression drops right? And to bring it back up, you mill and clean up the head right? But what if you don't shave the head to raise compression back? Will the engine lack in HP apposed to a ported/shave head engine? I ask because I see that Jr.Amsoil has a ported engine, but not head work. Just curious thats all.
Nik!
I have a question about a ported engine. When Ger ported my engine, he told me to expect a 15+ HP gain. It really did show, because after the porting the engine really opened up. But what my question is, When you port an engine the compression drops right? And to bring it back up, you mill and clean up the head right? But what if you don't shave the head to raise compression back? Will the engine lack in HP apposed to a ported/shave head engine? I ask because I see that Jr.Amsoil has a ported engine, but not head work. Just curious thats all.
Nik!
the compression will be lower than before if the heads are not shaved
yeah, I knew that. but lets talk HP, any loss?
yep you will loose some torque and hp..i'm sure don will anwser it pretty soon
Yeah, With all the porting he does he should have done some dyno comparisons, But who knows!
valin
Active member
The reason the motor loses compression is because there is a small amount of area taken out on the top of the exhaust port. This results in a smaller distance to TDC (Top Dead Center) after the piston passes by the port (closes the port). Therefore, there is less air/fuel that is compressed in the motor. By simply shaving the heads (cutting 10 or 20 thou off the base), it will bring your compression back up, but it also increases your compression ratio, which is the total volume in your heads once your piston is at TDC. When you increase your compression ratio, more heat is contained inside the motor, and with pump fuel can result in detonation. What needs to be done is have the heads shaved down, then domed out again to maintain proper squish and maintain a pump fuel friendly compression ratio. Hopefully this makes sense to you.
yep who knows ..but i think he know a little bit more than uss :-))) great guy he is :-))
valin said:
You are the man. That makes complete sence to me. I know Ger told me he messed with the squish angle. I run 91-94 octane, without any det. problems what so ever.
Thanks, Ryan.
bluewho
Active member
YOU WONT BLOW IT UP ON A JACK STAND LOL bring it up i will show you how to do it.98700 said:
lollllllllllllllllllllllllllllllllll.......well i can do that too already burn 4 piston this year i know how to do it for sure :-))))
bluewho said:
OK LISTEN UP SMART ARS! LOL, its locked up in my school until march 17 now!
bluewho
Active member
School is open a hour north of you.Stocking up on mothballs as i speak.LMAOSHICW
^ Highschool? I have march break from now until the 17th, lol.
RJH
New member
98700 said:
15 HPYou had a fantastic engine stock. Nice power band to work with. Very sturdy. Just rips...
Porting your engine - maybe 1 to -1HP from just porting, in my humble opinion. You probally have lost about 100 RPM out you power band also.
Good luck with it - it might not be too bad. Taking compression away - may let it rev nicer at top end.
RJH said:
You had a fantastic engine stock. Nice power band to work with. Very sturdy. Just rips...
Porting your engine - maybe 1 to -1HP from just porting, in my humble opinion. You probally have lost about 100 RPM out you power band also.
Good luck with it - it might not be too bad. Taking compression away - may let it rev nicer at top end.
How is that funny? full engine porting along with the head work, and supporting mods will yield a hell of a lot more than -1hp to 1hp!
RJH
New member
98700 said:
Possibly on some engines...but you were talking about porting only.
Did you get the snow we did in Niagara. The dudes were golfing last week and today its like were in the snow belt - instead of the Banana belt.
Problem is - my sleds up north - who would have thought
LOL! When porting is done 90% or mroe of the time the heads are shaved and squish angle is fixxed up. So when I say porting, Thats means the whole thing. Ported, and heads done.
But I just got in now, And At my moms restaurant, there was 10-15" in the driveway! The wind has to do with that.
But I just got in now, And At my moms restaurant, there was 10-15" in the driveway! The wind has to do with that.
rx1mtnman
New member
I have porting question also
My wifes viper burned up magneto side piston and cylinder. I found a cylinder with only 888 miles on ebay however it had been ported. I emailed seller and asked if it would be a problem that my other cylinders were not ported he said no butt might need to run different size jets on that cylinder. Is this correct? Should I run this cylinder on PTO side were there is less compresion or should I port the other two cylinders or should i try to find another cylinder?
My wifes viper burned up magneto side piston and cylinder. I found a cylinder with only 888 miles on ebay however it had been ported. I emailed seller and asked if it would be a problem that my other cylinders were not ported he said no butt might need to run different size jets on that cylinder. Is this correct? Should I run this cylinder on PTO side were there is less compresion or should I port the other two cylinders or should i try to find another cylinder?
RIVERRUNNER
Active member
I wouldn't run a ported cylinder and a non ported cylinder at the same time....
wilsviper
New member
Ported my Viper this winter.Gained two to three sled lenghths over the wife's
stock Viper.
stock Viper.