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heads

15K views 39 replies 19 participants last post by  CHAINSAW 
#1 ·
i keep looking at all these head jobs out there,and i just cant justify 1200 bucks for a head job,they are changing springs 100 bucks,valves prolly 150,and they put it on a cnc.maybe some hand polishing,i dont know thats just to much,in my opinion.your taking the heads off and sending them,they just clean em up.its not like they put in 40 or 50 hrs on them,just sayin
 
#11 ·
I have a set of ported, polished and shaved (.020) Big Boyz heads with compression releases on my bike with H-D S/E 9.6:1 forged pistons, which with the .020 head shave yields an effective 9.8:1 comp. ratio. If I was running anything bigger than a 37G cam, I would have gone bigger on valve size. I still have the stock heads for future consideration on that. Won't be any time soon, though. I like it as it is for now.
 
#3 ·
Not sure where you're looking, alot of places do heads for $299, $499, $599, $699.
Yes, if your paying someone to remove and replace that'll add more, but there's alot of really good heads out there for way less than $1200.
 
#4 ·
Not to excuse the high price of head jobs, but check the price on a 3 axis CNC mill sometime, and see what that will set you back! Ain't no free lunch. That said, if you shop around, you can get "CNC port jobs" for anywhere from around $300-$700. I think even the MoCo has a $700 or so exchange job. It's the jobs that involve handwork, and validation on a flow bench, when you start getting into the $1000+ territory. Again, a flow bench ain't cheap.

Jeff
 
#5 ·
Doing the heads as a performance upgrade is highly overrated IMO. A decent set of performance heads will only give the bike another 7-8 lbs of rear wheel torque over the stock heads and if you do the math you are not getting much bang for your buck. Spending your money on a big bore kit, good cam, tuner and a custom dyno tune will get you all the torque that you will need for everyday riding. My bike is a 96 inch engine and I had the 103 inch big bore kit put in with SE 255 cams with a SERT and I am using the stock heads and had the bike custom dynoed and I am getting just over 107 lbs of rear wheel torque. Save the head upgrade until you need to get the top end rebuilt if you still have the bike by then.
 
#6 ·
Have you checked with Drago? I think I saw on his site he charges $600 for CNC porting.. maybe that was per head though

I know you can get a damn good port job from AMS machine down in Ft Worth for $499. We've sent several sets off from up here and nothing but good stuff comes back.
 
#8 ·
You get what you pay for.

I have paid $300 right up to $1400 for heads. And another 6-8tq/hp might be 10% more than you had before.

I use R&R heads only now, as they have consistently given me better numbers than others. As long as the heads and cams are matched, then your half way there. Performance is never cheap.
 
G
#9 ·
We've performed performance cylinder head work here, loooooooooooooooong before these internet sites were even thought of.
Early T/C heads will choke the hp as much as 10-12 hp, with even a little Andrews 37, say nothing about larger cams, and later model heads can also do the same, depending on the build.
MANY variables that encompass cylinder head mods, but our hand-ported heads(that is how a "good" CNC heads starts life, from a digitized "master" head) hit the flow bench twice, each head, to insure that our folks get what they pay us to do.:)
Scott
Scott I'm looking to get a set of Stage 3 heads done for my Procharged '09 107" FLTR.What would you charge and exactly what would you do to these heads to get maximum performance.My goal is to get around 215hp. when all is said and done.
 
G
#10 ·
I didnt realize you hand ported heads until I reread your post .That concerns me a great deal.I dont feel you can match a set of heads perfectly by hand porting them.I'll just stick with the sure thing and go with Dragos Heads.I'm presently running a set of his stage2 heads and they have been nothing short of awesome, I'm like everyone else ,eventually enough isnt enough.Kevin
 
#12 ·
Then again, it's probably not unusual for "CNC ported" heads to start out life as a set of hand ported heads, which are then either scanned with a laser, or mapped with a stylus to make the CNC program to begin with!

Jeff
 
#13 ·
Anybody can rattle a milling cutter around the inside of a port and call it a CNC job. Just because a head is "CNC'd" means squat about how it performs. People have been hand porting heads, good and bad, pretty much since the first internal combustion engines hit the road, many of the best performing heads in the world are roughed out on a CNC machine before being hand finished.

There's alot more to it than the machine used to do the cutting. I see people screw up work on CNC machines every day. The person that will blindly pick a set of CNC heads over the hand ported just because they say "CNC" on them is the very same person being talked about in the "a fool and his money" story.
 
#14 ·
Frank, if I ever decide to have my other heads worked on, I'll be sending them to you.
 
#16 ·
Seeing as how your in Georgia, then a quick trip to Mineloa, FLA, to Doc's Performance Tuning (.com) would insure a world-class tune if heads are ever brought into the pic.
BTW he, as well as 2 other tuning centers across the US, showed between 106-108 hp, and 108-111 ft/lbs, our Stage II Heads/37 cams/98", @ 10:1 cr, last spring.:)
Scott
Scott, Doc's has been recommended to me before by Bluzmn59. One of these days I'll get down there and have him tweak my bike.
 
#20 ·
Outstanding! I will definately be calling you soon to discuss this option. Do you think a local dealer will be capeable of tuning the bike properly afterwards?


Yes you will always see a benifit. Bike will run cooler your atomized of fuel where it will burn better better fuel burn better power more.
This just simple example there is much more to this I can write a 2/3 page report on this.:D
Porting = increased cylinder filling. The more air into the engine the more atomizied fuel will follow. Also more power will happen. Very simple concept if done right. If done right you should see a 1/2 hp gain for every cubic foot per meter. Its is called CFM. Thats 5 hp for every 10 CFM.

Example are DBW $560.00 stage 1 cnc port jobs on HD/SE big bore kits we have seen
8/10/12 hp gains.

But in simple terms yes again if head work is done right it will benifit.
Please give us a call if you have any questions. Would be more than happy to help..... And explain anything questions you have. Even you dont use us..

Happy New Year.
FD.
 
#21 ·
Yes you will always see a benifit. Bike will run cooler your atomized of fuel where it will burn better better fuel burn better power more.
This just simple example there is much more to this I can write a 2/3 page report on this.:D
Porting = increased cylinder filling. The more air into the engine the more atomizied fuel will follow. Also more power will happen. Very simple concept if done right. If done right you should see a 1/2 hp gain for every cubic foot per meter. Its is called CFM. Thats 5 hp for every 10 CFM.

Example are DBW $560.00 stage 1 cnc port jobs on HD/SE big bore kits we have seen
8/10/12 hp gains.

But in simple terms yes again if head work is done right it will benifit.
Please give us a call if you have any questions. Would be more than happy to help..... And explain anything questions you have. Even you dont use us..

Happy New Year.
FD.
what about the tq? what are you seeing as far as gains with this setup as that is most important part of the mix when you are dealing with this type of camin a 900lb bike.if it makes 10 hp more at 5500 that will generally never be felt because bike is not running in that rpm range .do you have any dyno sheets with the stage 1 cnc work and cams on stock 103 ? thanks pete
 
#22 · (Edited)
Intake valve size, valve shape, guide shape, port volume, throat diameter, port ID, seat machining(ie valve job) along with the corresponding exhaust port requirements, all add up to the ability for the cylinder head to create great cylinder fill characteristics, when combined with a cam and compression, for the intended riding porpose.
Mid lift flow numbers will alert the savy builder as to how good the head is running, as the valve is that position, more that at peak, or when it is on the seat.
One other thing I will also make mention of, is the proper volume of air, paticularly on larger power plants, along with velocity, to be able to maintain a cool running engine, and the ability for a tuner to easily tune a given combination.
The proper throttle body, air cleaner element, and exhaust system all pull it togather to expose the worth of what has been built.
Very simple, if all of the abouve is adhered to.:)
Scott
 
#23 ·
very well said Scott, we all learn a little bit everyday. There is a reason we spend our days (and nights) testing on the flowbench and on the dyno. Nothing better when a combination comes together
 
#24 ·
Porting and polishing an engines intake manifold is a very importened step in optimizing its performance and more benafits if it is a modified engine. Porting is the a step in which material on the intake manifold is removed to open up and enlarge the ports while polishing smooths out the surface.
(But to much polishing can be very bad.) Both methods optimize and atomize air flow into the motor and will increase hp and tq if done right. The job cam be very labor intensive and expensive if you pay someone to do it but it can be done by yourself with the proper tools.;)

If done right you should you should see .5hp gain per cfm. Thats a 5 hp for every 10 cfm.:D
 
#25 ·
Polishing on these intakes will not harm, like automotive application, where the runners are much longer, and fuel, that comes out of suspension, can gather in the port/intake manifold.
These motorcycle induction systems are MUCH different, with the Y manifold, and the cross-talk between the 2 cylinder, odd fire engine.
Polishing is no where as important as the shape, and volume of the plenum, and the cylinder head's intake tract.
Scott
 
#26 · (Edited)
My 2 cents and what we see.. A rough surface reduces air drag. Smooth surface air moves slow.. A smooth surface accumaltes air psi. The air becomes stagnett air and will mess with air flow. A slight rough surface eliminates what to they call it boundray layer & increases air flow. We try to bead and scuff up are intake ports because we dont want are fuel to drop out. We have found if we polish to much it messes with our Air/Fuel mixter. We like the rough or bead surface it keeps the fuel in the air suspended in the port stream. Then we see better cumbustion. We do a lot of testing because we build a lot of blower engines from HD to Metric for over 12 years on bikes. Plus it helps when I had very special training from a (very big head company)...... When I used to build race cars..... When I was part owners of a car shop.....
Thanks FD


QUOTE=Hillsidecycle.com;165678]Polishing on these intakes will not harm, like automotive application, where the runners are much longer, and fuel, that comes out of suspension, can gather in the port/intake manifold.
These motorcycle induction systems are MUCH different, with the Y manifold, and the cross-talk between the 2 cylinder, odd fire engine.
Polishing is no where as important as the shape, and volume of the plenum, and the cylinder head's intake tract.
Scott[/QUOTE]
 
#28 ·
Thanks Frank for that explanation ,was thinking along the same lines. But thought maybe i was wrong ,good to hear from an expert

My 2 cents and what we see.. A rough surface reduces air drag. Smooth surface air moves slow.. A smooth surface accumaltes air psi. The air becomes stagnett air and will mess with air flow. A slight rough surface eliminates what to they call it boundray layer & increases air flow. We try to bead and scuff up are intake ports because we dont want are fuel to drop out. We have found if we polish to much it messes with our Air/Fuel mixter. We like the rough or bead surface it keeps the fuel in the air suspended in the port stream. Then we see better cumbustion. We do a lot of testing because we build a lot of blower engines from HD to Metric for over 12 years on bikes. Plus it helps when I had very special training from a (very big head company)...... When I used to build race cars..... When I was part owners of a car shop.....
Thanks FD


QUOTE=Hillsidecycle.com;165678]Polishing on these intakes will not harm, like automotive application, where the runners are much longer, and fuel, that comes out of suspension, can gather in the port/intake manifold.
These motorcycle induction systems are MUCH different, with the Y manifold, and the cross-talk between the 2 cylinder, odd fire engine.
Polishing is no where as important as the shape, and volume of the plenum, and the cylinder head's intake tract.
Scott
[/QUOTE]
 
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