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Engine Mechanical TopicsDiscussion for motor builds, cams, head work, stripped bolts and other engine related issues. The good and the bad. If it goes round and around or up and down, post it here.
Got a question for those more knowledgeable than me. Have a 128 M8 with the original SE CNC ported heads. Been thinking about swapping to a different cam and two cams I have been looking at are Feuling 508 and 538. Specs on the cams are very similar, with lift probably being the biggest difference between the two.
Flow on the SE CNC heads seems to stop increasing somewhere between .500 and .600 lift, with intake flow actually a little less at .600 than .500. Ill include specs on both cams and flow sheet on the heads from FM below. So here is my question - Is there any benefit of going with the 538 cam over the 508, if the heads dont flow more in the extra lift area of the 538? Does the 538 cam profile offer any power gains over the 508 in a bigger 128 motor? I was told by one shop to go with the 538 in the 128 and it would be a torque monster with rest of my build, but cant find hardly any info or dyno sheets to see where and how they produce power. I was looking at these cams, as I really like a fast revving bike. If the SE heads limit power in the extra lift area of the 538, I would probably prefer the lower lift cam and avoid any stress the higher lift cam may create. Any advice is appreciated.
Last edited by txphatboy; Mar 14, 2022 at 07:53 PM.
damn,i good set of ported CVO 110 heads flow better than that.to answer you question,if both cams will deliver power in the same RPM range your looking for,dont bother using a cam that has a higher lift than your heads are flowing (id have someone who does good porting get thosec heads flowing to where they should be & go with the bigger cam)
Pray tell VTR, what should a "good set of 110 heads flow" if ported by someone "who does good porting"?
If the heads are still flowing at .600" lift and I was hunting HP, I would go with the higher lift cam.
It's not the max lift that is important, it's the area under the curve that is important. Max lift is an instant, but the area under the curve is where the power is made. Look at how many degrees the cam is over .300" lift, .400" lift, and the one that is open longer will make more power. People try to determine what a cam will do based on max lift, and that isn't the most important part of cam grinding.
[QUOTE=VTR;20502461]damn,i good set of ported CVO 110 heads flow better than that.to answer you question,if both cams will deliver power in the same RPM range your looking for,dont bother using a cam that has a higher lift than your heads are flowing (id have someone who does good porting get thosec heads flowing to where they should be & go with the bigger cam)[/
What do you think these heads should flow?Wasnt really posting to evaluate the heads. The stock M8 heads flow pretty good and these SE heads flow a little better. Not looking to pull heads and do any extra porting - bike already makes 140+ hp/tq. Just thought a cam with some extra lift and duration might suit the 128 a little better. Currently running a S&S 475, and am going to retune, so now is time to consider cam swap.
It's not the max lift that is important, it's the area under the curve that is important. Max lift is an instant, but the area under the curve is where the power is made. Look at how many degrees the cam is over .300" lift, .400" lift, and the one that is open longer will make more power.
I understand looking at a flow sheet for heads and seeing how they perform at different lifts, but how do you do that with cam data that manufacturers provide?
Pray tell VTR, what should a "good set of 110 heads flow" if ported by someone "who does good porting"?
If the heads are still flowing at .600" lift and I was hunting HP, I would go with the higher lift cam.
He wouldn't know any more than his alter ego. He thinks 265 is good.
I'd take those cnc heads and have someone that DOES know how to get them to flow, finish working them. I can tell you the guy that just finished mine STARTS with a cnc ported head and FINISHES them. He got mine flowing 320+cfm @ 28" @ 600 lift.
Last edited by 60Gunner; Mar 17, 2022 at 09:04 AM.
Why is everyone with TC heads pumping their chest over how much increase in flow they can get at higher lift when comparing the numbers to a 4 valve head? Valves are smaller..
Personally I don't much difference between the 2 cams. I'd go for the one with less lift. It's going into a 128, you will likely have more power than you'll ever need unless of course you pick a crappy exhaust system.
Not sure why everyone keeps focusing on porting the heads - no plans for any more headwork. Current SE heads flow fine - 338cfm at .500 lift. I wish my old ported TC heads flowed like these between .300 and .500 lift.
Anyways, I was trying to decide between current SS475, Feuling 538, and SS540 cams. I went ahead and bought the 540 today. From what I have seen from a couple guys that went from 475 to 540 cam, is they all saw a nice bump, power kicks in early and pulls hard to redline, and videos of 540s accelerating seem to bury the speedo quick for a torque cam. I like the 475, but just want a little more. Was going to retune on dyno anyway due to some popping at heavy throttle, so now is the time to try a cam swap.
Yeah, I like them too. If I was not going to retune, I probably would have left them, but since I need to have bike dynod, now is the time to try a different set of cams.
The 475 pulls nice, but if the 540 pulls a little harder and faster (like described by others who have used both), I think I will be happy. A forum member on here said the 475s had awesome pull, and the 540s were similar, just pulled harder and faster. Ill see. I also just picked up a SE Extreme ported 64mm manifold to replace the regular SE 64mm manifold.
Will probably install manifold this weekend, swap cams in next couple weeks, and then have Dyno Difference tune it.
Last edited by txphatboy; Mar 18, 2022 at 07:54 PM.
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Cam lift and Head flow
