Please Help!!!Do I run 9.8,10 10.5? Can 10.5:1 be reliable???
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Tourer
Joined: Jan 2010
Posts: 273
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From: Ventura,CA
Please Help!!!Do I run 9.8,10 10.5? Can 10.5:1 be reliable???
First off Hello and I appreciate and Thank You for your input and help.
I am just finishing up collecting the parts for my new motor and I have just a few questions left.
Parts for build: Woods TW-6G and S&S Gears,S&S Lifters, Branch #4 heads, Branch 10.5:1 Pistons, and Daytona Twin-Tec TC88 Ignition, and already have the ThunderHeader and SE Heavy Breather on the bike.Also probably gonna use a Woods K1 needle and do a rejet.
I am looking for a killer street motor and obviously shootin for 100/100 and early torque obviously. My biggest questions are about reliability,detonation(and the problems with it),pinging,valve train wear all that stuff.
I want my motor to last a long long time and plan on riding it like a CR250 dirt bike basically lots of wheelies, plenty of rev limiter hits, riding in a pack lotsa miles and over 100+ alot of the time.
So with that in mind I am concerned about running the higher compression in my motor(12,000 miles currently) so I am having Branch cut the pistons down to 10:1 and we are planning to run a .040 gasket to achieve 9.8:1 CR. But the more I read it seems like tons of people are running 10 and 10.5 and am now second guessing myself.
So my questions are what would you do?will I get to 100/100 at 9.8?How reliable can I keep a 10:1, How reliable can I keep a 10.5:1,and if I did go 10 or 10.5 how do I keep the detonation away? And anything else you recommend. Thank you for your time. I am definitely hoping for the heavy hitters to chime in like Hillside and the Good engine builders and anybody else that does Thank You. Joe aka Jobo
I am just finishing up collecting the parts for my new motor and I have just a few questions left.
Parts for build: Woods TW-6G and S&S Gears,S&S Lifters, Branch #4 heads, Branch 10.5:1 Pistons, and Daytona Twin-Tec TC88 Ignition, and already have the ThunderHeader and SE Heavy Breather on the bike.Also probably gonna use a Woods K1 needle and do a rejet.
I am looking for a killer street motor and obviously shootin for 100/100 and early torque obviously. My biggest questions are about reliability,detonation(and the problems with it),pinging,valve train wear all that stuff.
I want my motor to last a long long time and plan on riding it like a CR250 dirt bike basically lots of wheelies, plenty of rev limiter hits, riding in a pack lotsa miles and over 100+ alot of the time.
So with that in mind I am concerned about running the higher compression in my motor(12,000 miles currently) so I am having Branch cut the pistons down to 10:1 and we are planning to run a .040 gasket to achieve 9.8:1 CR. But the more I read it seems like tons of people are running 10 and 10.5 and am now second guessing myself.
So my questions are what would you do?will I get to 100/100 at 9.8?How reliable can I keep a 10:1, How reliable can I keep a 10.5:1,and if I did go 10 or 10.5 how do I keep the detonation away? And anything else you recommend. Thank you for your time. I am definitely hoping for the heavy hitters to chime in like Hillside and the Good engine builders and anybody else that does Thank You. Joe aka Jobo
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Joined: Sep 2009
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From: The Internet (& Dyer, Indiana)
Cutting down the compression puts you in a safer zone.
Cutting down the compression also takes away power.
You have to "walk the line" if you want to play hard.
If you are just looking for some extra grunt and have a nice ridable "fun to cruise" bike, stay with the lower side of that margin.
If you want to pass your cocky pals and win the races, keep your compression near the top (for that cam).
But if you ain't into racing your pals, and just want the extra grunt for cruising, then back off the compression. You'll be fine. Compression is power. The last few points are where the max power is at.
You will lose a few ponies backing off the compression, but you will gain some easier starts on hot August days.
Need to find out what your "overall main objective" is.
If you want the most from your motor, then ride the max compression that your cam performs at.
Personally, I am walking the line at 10.4:1 with 206 ccp and am enjoying every minute of it!
I just think it is such a waste of money and effort, to put money into a build and then back off the compression for "other" reasons.
If you want extra grunt but no compression, then forget about headwork and all the other costly stuff, and toss in a baby-cam and tune and be on your merry way.
..
Cutting down the compression also takes away power.
You have to "walk the line" if you want to play hard.
If you are just looking for some extra grunt and have a nice ridable "fun to cruise" bike, stay with the lower side of that margin.
If you want to pass your cocky pals and win the races, keep your compression near the top (for that cam).
But if you ain't into racing your pals, and just want the extra grunt for cruising, then back off the compression. You'll be fine. Compression is power. The last few points are where the max power is at.
You will lose a few ponies backing off the compression, but you will gain some easier starts on hot August days.
Need to find out what your "overall main objective" is.
If you want the most from your motor, then ride the max compression that your cam performs at.
Personally, I am walking the line at 10.4:1 with 206 ccp and am enjoying every minute of it!
I just think it is such a waste of money and effort, to put money into a build and then back off the compression for "other" reasons.
If you want extra grunt but no compression, then forget about headwork and all the other costly stuff, and toss in a baby-cam and tune and be on your merry way.
..
Last edited by Faast Ed; Mar 27, 2010 at 06:18 PM.
Thread Starter
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Tourer
Joined: Jan 2010
Posts: 273
Likes: 1
From: Ventura,CA
Yeah Ed that's what I am kinda leaning towards because I keep hearing that with my light bike and good ignition I can keep the pinging down and see thats exactly where the max is for the cam too. I think I'll be passing most of my buddies anyways cuz nobody really has the goods like this. So yeah I'm really stumped because the thought of better reliability sounds very appealing but then again so does more power so I'm stumped. How many horsepower and torque will I lose by those two compression points?
Banned
Joined: Sep 2009
Posts: 7,580
Likes: 7
From: The Internet (& Dyer, Indiana)
Yeah Ed that's what I am kinda leaning towards because I keep hearing that with my light bike and good ignition I can keep the pinging down and see thats exactly where the max is for the cam too. I think I'll be passing most of my buddies anyways cuz nobody really has the goods like this. So yeah I'm really stumped because the thought of better reliability sounds very appealing but then again so does more power so I'm stumped. How many horsepower and torque will I lose by those two compression points?
It's more like "am I looking for the max" or not.
As I said earlier, the cruising fun could have been done with out all the headwork. You spent some money, I'd think you wanted the most from the build.
An excellent tune is key here. Running the max compression absolutely requires a tuner that can minimize your ping and hot starts.
I have no regrets running the line, but I had the luck of having a good tuner. You spent money on headwork, it would be hard for me to settle for less than optimum power by "intentionally" leaving the compression lower than optimum for a specific cam.
A few tenths won't rob you of much. But when your buddy passes you on a WOT stretch, you have to live with it.
This is a call only you can make. But you have to live with it.
Thread Starter
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Tourer
Joined: Jan 2010
Posts: 273
Likes: 1
From: Ventura,CA
Well I did get everything for half price so I think I may be able to live with 9.8 but I guess I'm just wanting to know how big of a difference it is ya know? Will it pick the front wheel up? I mean I DO have some decent stuff here I believe. Thanks
Banned
Joined: Sep 2009
Posts: 7,580
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From: The Internet (& Dyer, Indiana)
9.8 ain't bad.
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Cruiser
Joined: Jan 2009
Posts: 124
Likes: 5
I say go for it!. Try to keep ccp close to 200 an with a good tune it should be a screamer.
Have a S&S Evo in a shovelhead FL frame setup at 195ccp,thunderheader, Hi4 ignition,PowerHouse cam and it puts BIG grin on my face whenever I twist the wick!
Have a S&S Evo in a shovelhead FL frame setup at 195ccp,thunderheader, Hi4 ignition,PowerHouse cam and it puts BIG grin on my face whenever I twist the wick!
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Road Warrior
Joined: Oct 2007
Posts: 1,398
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From: Lafayette, IN.
I ran 10.5:1 on my 2000 Softail for the last 20k miles that I owned it. I had Andrews 60G cams, polished and ported heads and a super duper jet kit. My number were more like 98hp/100tq.
The bike was a ton of fun and was totally reliable. I ran premium gas and never had any pinging issues. The only thing that I would have done differently if I were to do that build again is, I would have used compression releases. Folks told me that my build was right on the border where I could use them or not. I felt that the starter worker pretty hard turning the engine over.
Other than that, do it up and enjoy it.
The bike was a ton of fun and was totally reliable. I ran premium gas and never had any pinging issues. The only thing that I would have done differently if I were to do that build again is, I would have used compression releases. Folks told me that my build was right on the border where I could use them or not. I felt that the starter worker pretty hard turning the engine over.
Other than that, do it up and enjoy it.