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CVO Technical => Twin Cam => Topic started by: Fullshed on September 10, 2005, 09:51:33 AM
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The large sized combustion chamber of the CVO heads (does anyone know how many cc's they actually are?) when run with the standard flat topped pistons gives a claimed compression ratio of 9 to 1, but the corrected compression ratio is actually only 7.8:1 given the 253 cams don't close the inlet valves until 53 degrees ABDC (always assuming I'm using the compression spreadhseet correctly). There's also no quench or squish using flat tops in a straight hemispherical chamber.
So my question is has anyone modified either the 103+ or 103 HTCC pistons (or any other brand for that matter) to match the CVO chamber? It seems to me that this should be possible and would not only get the compression ratio up (I'd like about 9.7:1)but would also provide some quench area. In effect this would mimic what Hemi Design do with their heads & pistons. Or have I got it all wrong?
I know the compression can be raised by using a 30 [smiley=xyxthumbs.gif]thou Cometic head gasket and the heads can also be decked but that doesn't address the lack of a quench area. But then perhaps that's not such a problem as the new 113 SE pistons look to be slightly concave so they're certainly not going to provide any quench in a 103+ chamber either.
All very puzzling as I try to work out the best way to build this 103. I suppose I could just use the 103+ heads and pistons but then I'm stuck with 10.5:1 and have to use a hotter cam profile than I want to run in a Road King. I also don't have the posh SE 103 script on the heads!
I'd also appreciate anyone's thoughts on what cams to run assuming I can get the compression ratio to 9.7:1 or so. I'm looking for smooth torque from 2,500 to 5,500, with most of my riding being in the sub 4000 range. I'm happy to run to the rev limiter occasionally but its not going to happen every ride. I've also heard that some cams give a lot of valve train noise so I want to stay clear of those.
So what say you??
Bill
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Hi Bill
I had my cvo done last spring and the head cc's were 94. Also I used the SE 103+ and Underground did the heads. With the .030 head gasket, they figured just over 10.5:1. The thing runs perfect, way better than stock as far as being smooth and no surging when cold. It's like turing on an electric motor. I put the cruize on the other day and ran 75 mph for 200 miles and only put in 4 gallons. Way better mileage too. It has never pinged either. The builder built a custom PC usb map.
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Bill,
I have an 04 SE 103", the heads were huge. I had Short Block Charlie (SBC) in Phoenix, redo the heads, welded up combustion chambers for better "squish", went with the S&S 585 Dear Drive cams, pistons and rest of engine stock, compression is 10:1. Have Freddom Exhaust, SERT, HD 6 Speed. Frank (HIPPO) reassembled engine, now have apprx. 6,000 miles since done. No problems, no pinging. Get great mileage. Great highway bike, that is what I wanted.
Selling the 95" engine and HD stock tranny paid for majority of the build.
Dynod at 106 HP and 117 ft lb of torque. Will add Kuraykn WT 57 MM Throttle Body over winter and still tweaking to get better HP & TQ.
Engine is in a 03 Road Glide.
geezerglide
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Fullshed,
You can have your heads worked on the stock 103's have them Ported / polished have them add a band of squish they can then deck the 10.5 to 1 pistons and use a stock gasket and it should get you to 10.0 to 1. This will also if done correctly cause the heads to be high velocity and you wont have to do anything to the exhause valve leave it at 1.65 and then you could have a 1.91 intake put in and it should run great for you if this is the road your asking for vs paying 800 to 1000 bucks for new 103+ heads.
The SBCharlie setup is also a good proven way to go.
Right now there are several threads talking about cams and hop us take a look at those they should prove to be some good reading as there are a lot of opinions on this topic.
Decide if you want gear drive or chain tensioners and the rest should be just fitting you ot the right cam.
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Bill,
I have an 04 SE 103", the heads were huge. I had Short Block Charlie (SBC) in Phoenix, redo the heads, welded up combustion chambers for better "squish", went with the S&S 585 Dear Drive cams, pistons and rest of engine stock, compression is 10:1. Have Freddom Exhaust, SERT, HD 6 Speed. Frank (HIPPO) reassembled engine, now have apprx. 6,000 miles since done. No problems, no pinging. Get great mileage. Great highway bike, that is what I wanted.
Selling the 95" engine and HD stock tranny paid for majority of the build.
Dynod at 106 HP and 117 ft lb of torque. Will add Kuraykn WT 57 MM Throttle Body over winter and still tweaking to get better HP & TQ.
Engine is in a 03 Road Glide.
geezerglide
Geezer the 57mm throttle will be tooooooo much for your set up. Either have your stock unit modified or buy the Zippers 50mm. That will keep your volumetric efficeiency much higher. The bike will run better. That is JMO!!!!!!!
Be Safe
THE DAWG
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Fullshed,
You can have your heads worked on the stock 103's have them Ported / polished have them add a band of squish they can then deck the 10.5 to 1 pistons and use a stock gasket and it should get you to 10.0 to 1.
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Many thanks for your replies. I appreciate that the standard heads can be welded up and the combustion chambers reshaped/resized but to me it would be a lot easier to use a domed piston that will better fill the existing chamber. The pictures on the Hemi design site show the sort of thing I'm getting at:
http://www.hemidesign.com/pages/technical%20overview.html
From what I can see the combustion chamber on the Hemi Design SE head looks very much like the standard CVO chamber, which is what got me wondering whether either of the SE domed pistons (the 103+ or the 103 HTCC) would achieve the same thing in the CVO head. The other possibility may in fact to see what Hemi design say about their pistons matching the CVO head. I'll send them an email and let you all know what they say.
Bill
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fullshed, welcome to the site. I recognize your handle form HTT. Let us know what you find out. [smiley=beerchug.gif]
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DCFIREMAN,
Yes, I was thinking of Zippers TB, however I want to keep my cruise. Also, was thinking of modifying my stock TB. Who does the mod?
Were you not the high bidder on eBay for a Zippers TB, about a week ago?
Thanks for the suggestion,
geezerglide
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Geezer you can keep cruise control with Zippers ... I have a 50 mm that has cruise on it.
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DCFIREMAN,
Yes, I was thinking of Zippers TB, however I want to keep my cruise. Also, was thinking of modifying my stock TB. Who does the mod?
Were you not the high bidder on eBay for a Zippers TB, about a week ago?
Thanks for the suggestion,
geezerglide
As usual Unbalanced is correct. You do keep all of your stock options with the Zippers Thunder Max Throttle Body. I have had mine all season and the bike performes quite well. You would be very happy with one.
No actually that was a friend of mine that got that throttle body. I am going to install it this week for him. He has a new Street Glide and is getting the fat cats and Thunder Max ECM and throttle body all at the same time.
Be Safe
THE DAWG
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The 22516-04 piston kit is designed to work with the 103+ 17072-03 cylinder head. This results in 10.5:1 with 98cc domes. The CVO heads are roughtly 95cc. Shouldn't the CVO heads work with the 22516-04 mild dome pistons? How far has anybody gotten on any of this?
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Many thanks for your replies.
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I have to disagree about the 57mm Kuryakyn throttle body being too large for a 103. If it was a carburator yes it is too big, but a throttle body doesn't get its signals from the vacuum going across the venturi's like a carb does. Too big a carb will produce low velocity and thus low signals to the jets and result in a lazy engine. With fuel injection you can tune this thing to spit the right amount of fuel into the engine with it sucking the most air it can get. There is such thing as too big but I think 57mm isn't it. Besides, if next year 103 isn't big enough for you, you can go with the HD 113 or an Axtell 117 and wont have to get another bigger throttle body.
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They will not work..for what you are trying to accomplish. the Hemi Design heads have quench area built in all the way around the combustion chamber ...say at a 15 degree angle to the rest of the chamber...this angle is matched by the angle on their domed piston so you have the benefit of squish occuring in three planes instead of only two as in a normal bath tub chamber.
Just putting in their domed piston with no matching quench area in the head will probably just raise compression and actually make for poorer distribution due to the dome volume being in the way with no squish. ping city.
So the 22516-04 piston dome doen't match the quench area in the cvo heads?
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DCFIREMAN,
Yes, I was thinking of Zippers TB, however I want to keep my cruise. Also, was thinking of modifying my stock TB. Who does the mod?
Were you not the high bidder on eBay for a Zippers TB, about a week ago?
Thanks for the suggestion,
geezerglide
Geezerglide,
Another option you can look into is Horsepower Inc. You can also run cruise on their TB's. They offer 48, 51, 53 & 56mm. Then they have custom applications up to 62mm. Check them out @ horsepowerinc.net
Zippers is a very good reputable company, but this is just another option for you to look into.
Good luck with your build!!
Grover
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There is no real quench area in the CVO heads. Just a big old round chamber. So the answer is no .