Max. compression on EV46 cam
Thread Starter
|
Advanced
Joined: Dec 2007
Posts: 70
Likes: 0
From: Buenos Aires, Argentina
Max. compression on EV46 cam
Hi Evo lovers.
Lately my EVO Dyna has been consuming too much oil so I figured is time for a top end rebuild.
Last week I placed the order for a Wiseco 10:1 piston kit, and Cometic 0.030 gaskets kit.
I already have an EV46 cam, Mikuni carb ,Bassani Road Rage, Screamin Eagle adjustable ignition and the heads milled 0.030" (0,8mm for us).
Do you think I will have too much compression for this cam? I intend to CC the heads to know where I´m standing, but I would like to know where you would set the compression to avoid ping.
Right know I´m using the most agressive curve of the igntion, but I can always select one of the other 4 if that´s prevent detonation.
So, what do you guys think?
Lately my EVO Dyna has been consuming too much oil so I figured is time for a top end rebuild.
Last week I placed the order for a Wiseco 10:1 piston kit, and Cometic 0.030 gaskets kit.
I already have an EV46 cam, Mikuni carb ,Bassani Road Rage, Screamin Eagle adjustable ignition and the heads milled 0.030" (0,8mm for us).
Do you think I will have too much compression for this cam? I intend to CC the heads to know where I´m standing, but I would like to know where you would set the compression to avoid ping.
Right know I´m using the most agressive curve of the igntion, but I can always select one of the other 4 if that´s prevent detonation.
So, what do you guys think?
Road Captain
Joined: Sep 2012
Posts: 675
Likes: 32
From: Massachusetts
.030" *should* be about .3 onto your CR (assuming heads started @ 83cc)
wiseco 10:1's and a .030" head gasket will give you just over 10.0-10.1 ish CR....tis what I run in my bagger. so far no pinging, and runs like a champ (aside from the blown head gaskets, but thats a totally different story)
i personally wouldnt go much past 10.5:1 if you plan on being able to go anywhere (93 octane isnt always available...and it can get VERY detonation-prone much past that
EV46 IIRC has intake closing @ 41, almost identical to the W6H i'm running (which is 40)...not venting a whole hell of a lot of cylinder pressure, so keep that in mind.
BigBoyzCycles calculator puts you @ 10.22:1CR decking the heads .030, assuming you use a stock (0.045") head gasket. if you wanna save a few bucks, just run the .030" HG and end up @ 10.1:1CR
running the 0.030" HG with milling the heads, you'll be @ 10.55:1 (once again assuming you started @ 83cc on the head volume)
wiseco 10:1's and a .030" head gasket will give you just over 10.0-10.1 ish CR....tis what I run in my bagger. so far no pinging, and runs like a champ (aside from the blown head gaskets, but thats a totally different story)
i personally wouldnt go much past 10.5:1 if you plan on being able to go anywhere (93 octane isnt always available...and it can get VERY detonation-prone much past that
EV46 IIRC has intake closing @ 41, almost identical to the W6H i'm running (which is 40)...not venting a whole hell of a lot of cylinder pressure, so keep that in mind.
BigBoyzCycles calculator puts you @ 10.22:1CR decking the heads .030, assuming you use a stock (0.045") head gasket. if you wanna save a few bucks, just run the .030" HG and end up @ 10.1:1CR
running the 0.030" HG with milling the heads, you'll be @ 10.55:1 (once again assuming you started @ 83cc on the head volume)
Thread Starter
|
Advanced
Joined: Dec 2007
Posts: 70
Likes: 0
From: Buenos Aires, Argentina
Thank`s Jaspér, that was pretty much my idea, aim to 10.5 CR.
But couldnt find to much information about what kind of compression is people using with this cam.
Im happy with the performance now, but I would like a little of extra performance below the 3000 RPM.
Thanks for your reply.
But couldnt find to much information about what kind of compression is people using with this cam.
Im happy with the performance now, but I would like a little of extra performance below the 3000 RPM.
Thanks for your reply.
Road Captain
Joined: Sep 2012
Posts: 675
Likes: 32
From: Massachusetts
no problem. there's a reason ive gone through 5 cams lol
what you gain below 3k, you'll lose up top. pick any cam out there, and your peak numbers (torque--IE what you can FEEL) will be pretty similar. 90% of what your cam does is move your curve left or right based on where you want your power. personally my bike never see's much of anything below 2500-2700RPM, and i'm at or above 3k most of the time, so I wanted a cam that was on-demand-instant power for roll-on acceleration.
what you gain below 3k, you'll lose up top. pick any cam out there, and your peak numbers (torque--IE what you can FEEL) will be pretty similar. 90% of what your cam does is move your curve left or right based on where you want your power. personally my bike never see's much of anything below 2500-2700RPM, and i'm at or above 3k most of the time, so I wanted a cam that was on-demand-instant power for roll-on acceleration.
Thread Starter
|
Advanced
Joined: Dec 2007
Posts: 70
Likes: 0
From: Buenos Aires, Argentina
Yes, I get that, thats what Im looking to increase the compression, Im happy with the top end power but I want a little more in the botom end.
Compressión usually does that.
Compressión usually does that.
Novice
Joined: Jul 2013
Posts: 19
Likes: 1
From: CONUS
Static compression is not as important as corrected compression and CCP (cold cranking pressure). Regardless of the cam, an evo should generally be kept under 200 Lbs CCP. Measure the volume of each of the chambers in your cyclinder heads and then use the compression calculator on the Big Boyz website. You can almost ignore static or mechanical compression, just work the various numbers until you have achieved the desired CCP or corrected compression ratio. Then build to those specs.
I have a ran 80" evo with a 48 at approx 9.5 static compression for many years. Rode that bike all over the south east western desert areas for many years, never had an issue with gas but always felt it could have taken some more compression. I liked that cam, it had good legs and wanted to run.
I have a ran 80" evo with a 48 at approx 9.5 static compression for many years. Rode that bike all over the south east western desert areas for many years, never had an issue with gas but always felt it could have taken some more compression. I liked that cam, it had good legs and wanted to run.
Thread Starter
|
Advanced
Joined: Dec 2007
Posts: 70
Likes: 0
From: Buenos Aires, Argentina
Those are the kind of facts I was looking for.
All the data I read says to keep the corrected compression below 180 for a street engine. That seems a little low.
200 like you say, starts to sound about right.
If anyone else has experience with high compression evos in the street, please chime in.
I'm looking for real world experience.
All the data I read says to keep the corrected compression below 180 for a street engine. That seems a little low.
200 like you say, starts to sound about right.
If anyone else has experience with high compression evos in the street, please chime in.
I'm looking for real world experience.
Trending Topics
Tourer
Joined: Aug 2009
Posts: 359
Likes: 2
From: central Mississippi
I redid the top end on my '95. Installed JE 9.5 pistons, SE-4 cam, adjustable pushrods. Compression reads 200 on both cylinders, up from around 150 before the rebuild. Big difference in acceleration, especially Interstate riding. Happy with it so far. 16,000 miles on rebuild, no issues so far.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Southpaw Super Glide: A Left-Hand-Drive 1979 Harley FXE Built to Fit the Rider
Verdad Gallardo
The Best and Worst Harley-Davidson Moves of 2025
Verdad Gallardo
Thread Starter
|
Advanced
Joined: Dec 2007
Posts: 70
Likes: 0
From: Buenos Aires, Argentina
I redid the top end on my '95. Installed JE 9.5 pistons, SE-4 cam, adjustable pushrods. Compression reads 200 on both cylinders, up from around 150 before the rebuild. Big difference in acceleration, especially Interstate riding. Happy with it so far. 16,000 miles on rebuild, no issues so far.
Thanks for the help.
Best regards.
Thread
Thread Starter
Forum
Replies
Last Post
Tltrump
Exhaust System Topics
1
Jul 11, 2007 02:57 PM