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Duration vs Lift

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boater4life

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Just been thinking what the difference would be in these cams. HP/Torgue difference compared to wear. These would be going in a 525 so it is a tall deck with a 4.5 stroke. Older set of Dart 360 hard anodized heads. 1071 say 6lbs boost intercooled.
I was just thinking more duration with less lift would be easier on valve train. What do you think? I wish I had a dyno to play with vs just a PC with DD that never will compare to real world results. Thanks.

Crane
139021 New Zcam Hyd Roller 12LSA
In .610 lift - 296@.004 IO 37 IC 79, 234@.050 IO 10 IC 44
Ex .632 lift- 304@.004 EO 85 EC 39, 242@.050 EO 58 EC 4.0

Crane
139671 Hyd Roller 14LSA
IN .610 lift - 298@.004 IO 36 IC 82, 236@.050 IO 9.0 IC 47
Ex .632 lift - 306@.004 EO 88 EC 38, 244@.050 EO 61 EC 3.0

Comp
NX298HR 113LSA
In .566 lift - 298@.006 IO 41 IC 77, 242@.050
Ex .575 lift - 310@.006 IO 93 EC 37, 254@.050
 
Lift isn't usually the problem if you're buying good springs. Ramp speed tends to be though. Cams with an aggressive ramp are hard on everything. Blower motors don't need that big overlap- but they do need big exhaust flow- you may look into porting the exhaust ports.

You didn't ask this, but I see a potential problem.. 10-71 is alot of blower for that many CID. You're going to be under-driving it at 6PSI which is going to cause fuel puddling which will load it up and foul plugs at low RPM. 360 cc heads will compound that- you'll have low port velocities for that CID. And 6 psi is way low for an intercooler- at least any good one. No sense going through the hassle, unless the motor has 12:1's in it. The 525 is 4" stroke, not 4.5.
 
I agree, drivability will suck with that combination. Intake velocity will be slow with those heads and the blower will make idle and low speed response even worse. The only way to make it work would be to build it for 8 to 1 compression, 10 lbs. boost and spin it to 6500+ rpm. It wouldn't idle but with a thousand hp who cares. Woo hoo!

A lot of Comp hyd. roller cams have lower lifts compared to Cranes. Don't know why. Their opening ramps are just as steep if not steeper though. If you compare the Comp to the Crane above it, it has about the same intake duration at .004 but more duration at .050. That indicates a steeper opening rate. What does this all mean? My guess is that the Comp is an older grind. I have a Comp cam with .630 lift lobes. 236/240 duration. Modern springs are quite reliable up to about .700 lift. There is a little free hp with the higher lift and not much loss of drivability. I'd go for the higher lift.
 
Chris, Maybe it is a tall deck 427T block. Wouldn't that work out to around a 525ci with a 4.5 stroke and stoke bore? Those are some big a$$ heads for that motor unless you are going to spin the chit out of it.
 
Thanks guys and yea I know it is not the best combo but it is what I have. It is a truck block so I guess you could say a budget build if there is one. :) I have just been wondering about cams as there seems to be a lot of different thoughts on what is best for each build. I know .650 is not a high lift for some but just looking at how often some have to go through top end so it got me thinking about lift vs duration knowing a BBC likes some valve lift.

Actually I have not had any issues with idleing or fuel puddling in the past but this will be the first try with intercooler set up and my boost was just a starting point. As for CR for this build it will depend on my final piston choice and if i go with back with of the shelf pistons it should be around 8.25 - 8.5. I am a West coast boater so I boat in the heat and our gas sucks.

1000hp may be very possible but I would be happy with 800+ and dependable. Just trying to find a cam that will let it breath but not kill lifters.
 
Have you tried selling those heads. Dart 360's are a great head for big engines and high rpm's so they are popular with the drag racers. Then you could pick up a pair closer to 320 cc.
 
PatriYacht said:
Have you tried selling those heads. Dart 360's are a great head for big engines and high rpm's so they are popular with the drag racers. Then you could pick up a pair closer to 320 cc.
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That might be worth looking in to. Not sure anybody is buying much used but I will look and see if anybody is looking. I had these heads on a smaller boat with a 540 and turned more RPM with them before. I just thought the blower would help make for the large ports.
 
Trim'd Up said:
Chris, Maybe it is a tall deck 427T block. Wouldn't that work out to around a 525ci with a 4.5 stroke and stoke bore? Those are some big a$$ heads for that motor unless you are going to spin the chit out of it.
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Going to be hard to get 4.5" into the truck block and the cylinder walls aren't that thick on them to start with. And 1000 hp in an endurance engine in that block- there's alot wrong with this formula. Plus you're going to be at a 4.310 bore max- bad intake shrouding. Possible, but not recommended
 
In thinking about this, I'd give Bob Madara a PM. He's RMBuilder on the board. He does custom cams and did the pre-release testing on the Morel lifters- the new one that's supposed to be next to indestructible. He can model this whole thing with you and give you some suggestions.

My guess is (assuming you don't already have the 4.5" crank) is that he's going to recommend 4.25" for fit and rpm-range reasons.
 
If your looking for a camshaft recommendation please feel free to contact me at the shop (216) 398-8500. I design all of my camshafts for the engines I build and do a ton of marine supercharged stuff. I can get you the right cam the first time around.
 
boater4life said:
Thanks guys and yea I know it is not the best combo but it is what I have. It is a truck block so I guess you could say a budget build if there is one. :) I have just been wondering about cams as there seems to be a lot of different thoughts on what is best for each build. I know .650 is not a high lift for some but just looking at how often some have to go through top end so it got me thinking about lift vs duration knowing a BBC likes some valve lift.

Actually I have not had any issues with idleing or fuel puddling in the past but this will be the first try with intercooler set up and my boost was just a starting point. As for CR for this build it will depend on my final piston choice and if i go with back with of the shelf pistons it should be around 8.25 - 8.5. I am a West coast boater so I boat in the heat and our gas sucks.

1000hp may be very possible but I would be happy with 800+ and dependable. Just trying to find a cam that will let it breath but not kill lifters.
Click to expand...
I would call DEAN he may help you get better heads and he is on the money with his cams. he set up a friend of mine that had a 572 blow up after 5 hours his old cam set up gave him 930hp. with Deans help its gots 1050hp now. and Dean is putting together a 572 blower motor for me:sifone: he is MRhorsepower1 216 398 8500 ,
 
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