Good comparison roller vs tappet cam 350ci
03-23-2009, 01:38 PM
#1
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Good comparison roller vs tappet cam 350ci
Hey guys,
picked up my flywheel/pressure plate this week from being balanced and the speed shop was running a 350 on the dyno very similar to my build but with a non roller cam - does this make for a very good comparison on roller vs non roller cams?
Engine 1:
.060 over
10-1 CR
Edelbrock Perf heads
Comp hyd roller .502/.510 @ (.050) 224/230
RPM airgap intake
750 DP tuned carb
444hp (5700rpm) and 448tq (4600rpm)
Engine 2:
.030 over
10-1 CR
Edelbrock Perf RPM heads
Crane hyd flat tappet (don't remember exact grind but very close to above Comp specs)
Perf RPM intake
750 DP tuned carb
406hp (5600rpm) and 420tq (4500rpm)
Both blocks were decked and machined the same - same brand pistons were used and both set up .005 below 0 deck. Pretty close builds with the roller cam in the #1 engine as the biggest variable.
Other than the slight difference in displacement - is it a fair assumption to say that a roller cam is good for around 40hp/30tq in a sb?
picked up my flywheel/pressure plate this week from being balanced and the speed shop was running a 350 on the dyno very similar to my build but with a non roller cam - does this make for a very good comparison on roller vs non roller cams?
Engine 1:
.060 over
10-1 CR
Edelbrock Perf heads
Comp hyd roller .502/.510 @ (.050) 224/230
RPM airgap intake
750 DP tuned carb
444hp (5700rpm) and 448tq (4600rpm)
Engine 2:
.030 over
10-1 CR
Edelbrock Perf RPM heads
Crane hyd flat tappet (don't remember exact grind but very close to above Comp specs)
Perf RPM intake
750 DP tuned carb
406hp (5600rpm) and 420tq (4500rpm)
Both blocks were decked and machined the same - same brand pistons were used and both set up .005 below 0 deck. Pretty close builds with the roller cam in the #1 engine as the biggest variable.
Other than the slight difference in displacement - is it a fair assumption to say that a roller cam is good for around 40hp/30tq in a sb?
Last edited by ED69ray; 03-23-2009 at 01:47 PM.
03-23-2009, 06:12 PM
#3
Melting Slicks
Not necessarily. According to David Vizard and this article:
http://www.enginebuildermag.com/Arti...r_failure.aspx
"The problem of wiping out flat tappet cams could be prevented by going to a roller design. Two problems here: one is that a roller calls for more money; and two, unless the roller has a seat duration longer than about 270° to 275°, the flat tappet cam is likely to out-perform it.
In case you doubt the validity of this just check out the hydraulic intensity and lift figures of Comp Cams Xtreme Energy range of rollers and flat tappet cams. Although a crude comparison, the numbers indicate that until about the 270° mark is exceeded, a flat tappet cam is likely to give more opening area under the lift curve. If you want to impress a customer with the power you can build into a relatively low cost unit the higher intensity cams from any reputable company are the type to use."
http://www.enginebuildermag.com/Arti...r_failure.aspx
"The problem of wiping out flat tappet cams could be prevented by going to a roller design. Two problems here: one is that a roller calls for more money; and two, unless the roller has a seat duration longer than about 270° to 275°, the flat tappet cam is likely to out-perform it.
In case you doubt the validity of this just check out the hydraulic intensity and lift figures of Comp Cams Xtreme Energy range of rollers and flat tappet cams. Although a crude comparison, the numbers indicate that until about the 270° mark is exceeded, a flat tappet cam is likely to give more opening area under the lift curve. If you want to impress a customer with the power you can build into a relatively low cost unit the higher intensity cams from any reputable company are the type to use."
03-23-2009, 07:08 PM
#4
Not necessarily. According to David Vizard and this article:
http://www.enginebuildermag.com/Arti...r_failure.aspx
"The problem of wiping out flat tappet cams could be prevented by going to a roller design. Two problems here: one is that a roller calls for more money; and two, unless the roller has a seat duration longer than about 270° to 275°, the flat tappet cam is likely to out-perform it.
In case you doubt the validity of this just check out the hydraulic intensity and lift figures of Comp Cams Xtreme Energy range of rollers and flat tappet cams. Although a crude comparison, the numbers indicate that until about the 270° mark is exceeded, a flat tappet cam is likely to give more opening area under the lift curve. If you want to impress a customer with the power you can build into a relatively low cost unit the higher intensity cams from any reputable company are the type to use."
http://www.enginebuildermag.com/Arti...r_failure.aspx
"The problem of wiping out flat tappet cams could be prevented by going to a roller design. Two problems here: one is that a roller calls for more money; and two, unless the roller has a seat duration longer than about 270° to 275°, the flat tappet cam is likely to out-perform it.
In case you doubt the validity of this just check out the hydraulic intensity and lift figures of Comp Cams Xtreme Energy range of rollers and flat tappet cams. Although a crude comparison, the numbers indicate that until about the 270° mark is exceeded, a flat tappet cam is likely to give more opening area under the lift curve. If you want to impress a customer with the power you can build into a relatively low cost unit the higher intensity cams from any reputable company are the type to use."
to really compare the two you need to identical engines with exactly the same cam grind then you can tell if there is any gain.
i remember reading that in one of my rebuild books but i dont rember what one it was maybe it was the one by Vizzard but im not sure.
im going with Flat tappet unless my friend's dad wants it for his Drag racing car
Ryan
03-23-2009, 07:30 PM
#5
Race Director
i have to agree after reading that. the reason why roller is good right now is because of low Zinc levels causing Flatt Tappet Cams to get wiped lobes.
to really compare the two you need to identical engines with exactly the same cam grind then you can tell if there is any gain.
i remember reading that in one of my rebuild books but i dont rember what one it was maybe it was the one by Vizzard but im not sure.
im going with Flat tappet unless my friend's dad wants it for his Drag racing car
Ryan
to really compare the two you need to identical engines with exactly the same cam grind then you can tell if there is any gain.
i remember reading that in one of my rebuild books but i dont rember what one it was maybe it was the one by Vizzard but im not sure.
im going with Flat tappet unless my friend's dad wants it for his Drag racing car
Ryan
THe reason for a roller cam it you can get more lift with the same duration. So let's compare cams that way ( which is the only way I compare them, lift vs duration)
Look at a flat tappet cam say Comp 280H which has 230deg duration @ .050" and lift of .480"
Now look at the Comp Hydraulic roller 286HR with 230deg duration @ .050" and you get .560" lift.
Now which one are you going to put in your car for pink slips at the drag strip ?
03-23-2009, 07:43 PM
#6
Le Mans Master
I wouldn't leave untapped performance on the table just because it's possible for a poor roller build to be out done by a similar flat tappet one done well. Fact is that rollers are able to provide more lift for a given duration, hence more "area under the curve" than a flat tappet; an advantage worth taking if you've got the budget. Just don't waste money putting one in a dog that couldn't breath no matter what the cam and you won't end up an exception to the overriding rule that rollers are king.
TSW
TSW
Last edited by TheSkunkWorks; 03-23-2009 at 07:46 PM.
03-23-2009, 07:51 PM
#7
Race Director
If the cams have identical duration and lift then no doubt there is going to be no difference in power made, maybe a few ponies going to the roller cam because of less heat and friction.
THe reason for a roller cam it you can get more lift with the same duration. So let's compare cams that way ( which is the only way I compare them, lift vs duration)
Look at a flat tappet cam say Comp 280H which has 230deg duration @ .050" and lift of .480"
Now look at the Comp Hydraulic roller 286HR with 230deg duration @ .050" and you get .560" lift.
Now which one are you going to put in your car for pink slips at the drag strip ?
THe reason for a roller cam it you can get more lift with the same duration. So let's compare cams that way ( which is the only way I compare them, lift vs duration)
Look at a flat tappet cam say Comp 280H which has 230deg duration @ .050" and lift of .480"
Now look at the Comp Hydraulic roller 286HR with 230deg duration @ .050" and you get .560" lift.
Now which one are you going to put in your car for pink slips at the drag strip ?
The roller cam can take more hydraulic intensity or a faster ramp rate safely than a flat tappet cam, hence more lift with a given duration. The problem is the cam designers are always pushing the envelope with their flat tappet designs to beat out the competition on power generated from a given duration. It is not that the cams are crap it is that the cam engineers go right to or beyond what is considered safe hydraulic intensity. In doing this the cam lobe is subjected to more pressure, needs stronger springs and with the reduced ZDDP in the oils are more subject to damaged lobes. Then you got the guys that put 1.6 rockers on an already maxed lobe profile. It is this combination, along with the urge to wind out that more powerful build that is responsible for the higher instance of wiped lobes. JMHO
03-23-2009, 08:15 PM
#8
i guess you are right Moterhead i learned something new 
i am looking at 2 Hydraulic flat tappet cams both are from Com
COMP Cam 12-205-2 [49] 254H with an seat to seat Duration of 252 and .05 of 206 I & E with an lift of .390 for both I and E
COMP Cam 12-230-2 XE250H with an seat to seat of 250 I and 250 E the .05 is 206 I and 212 E the lift is .432 I and .444 E
being we are on the subject of pushing the envelope here are either of these over the limit's??
Ryan
i am looking at 2 Hydraulic flat tappet cams both are from Com
COMP Cam 12-205-2 [49] 254H with an seat to seat Duration of 252 and .05 of 206 I & E with an lift of .390 for both I and E
COMP Cam 12-230-2 XE250H with an seat to seat of 250 I and 250 E the .05 is 206 I and 212 E the lift is .432 I and .444 E
being we are on the subject of pushing the envelope here are either of these over the limit's??
Ryan
03-23-2009, 08:22 PM
#9
Burning Brakes
The comparison test has flaws.....
Heads have the same flow specs according to edelbrock site, but the different inlet manifolds, and the unknown cam grind (lift and duration) would contribute the major difference in peak power and torque.
If you had 2 identical motors: same capacity, same heads, same inlet and exhaust and had 2 cams with identical lobe shapes including the ramp rate, then there would be very little to seperate the results. The reduced friction of the roller lifters wouldn't really be noticeable.
The big advantage with roller cams is the increased ramp rate available to get the valves opened earlier in the cycle. The average lift of the valve during the inlet cycle is higher even though it may have the same duration and lift specification as a flat tappet cam.
That's where the torque and power advantage is... average valve lift is higher, so average inlet flow is greater, more fuel gets in, and more grunt is supplied!
Heads have the same flow specs according to edelbrock site, but the different inlet manifolds, and the unknown cam grind (lift and duration) would contribute the major difference in peak power and torque.
If you had 2 identical motors: same capacity, same heads, same inlet and exhaust and had 2 cams with identical lobe shapes including the ramp rate, then there would be very little to seperate the results. The reduced friction of the roller lifters wouldn't really be noticeable.
The big advantage with roller cams is the increased ramp rate available to get the valves opened earlier in the cycle. The average lift of the valve during the inlet cycle is higher even though it may have the same duration and lift specification as a flat tappet cam.
That's where the torque and power advantage is... average valve lift is higher, so average inlet flow is greater, more fuel gets in, and more grunt is supplied!
03-23-2009, 08:51 PM
#10
Hey guys,
picked up my flywheel/pressure plate this week from being balanced and the speed shop was running a 350 on the dyno very similar to my build but with a non roller cam - does this make for a very good comparison on roller vs non roller cams?
Engine 1:
.060 over
10-1 CR
Edelbrock Perf heads
Comp hyd roller .502/.510 @ (.050) 224/230
RPM airgap intake
750 DP tuned carb
444hp (5700rpm) and 448tq (4600rpm)
Engine 2:
.030 over
10-1 CR
Edelbrock Perf RPM heads
Crane hyd flat tappet (don't remember exact grind but very close to above Comp specs)
Perf RPM intake
750 DP tuned carb
406hp (5600rpm) and 420tq (4500rpm)
Both blocks were decked and machined the same - same brand pistons were used and both set up .005 below 0 deck. Pretty close builds with the roller cam in the #1 engine as the biggest variable.
Other than the slight difference in displacement - is it a fair assumption to say that a roller cam is good for around 40hp/30tq in a sb?
picked up my flywheel/pressure plate this week from being balanced and the speed shop was running a 350 on the dyno very similar to my build but with a non roller cam - does this make for a very good comparison on roller vs non roller cams?
Engine 1:
.060 over
10-1 CR
Edelbrock Perf heads
Comp hyd roller .502/.510 @ (.050) 224/230
RPM airgap intake
750 DP tuned carb
444hp (5700rpm) and 448tq (4600rpm)
Engine 2:
.030 over
10-1 CR
Edelbrock Perf RPM heads
Crane hyd flat tappet (don't remember exact grind but very close to above Comp specs)
Perf RPM intake
750 DP tuned carb
406hp (5600rpm) and 420tq (4500rpm)
Both blocks were decked and machined the same - same brand pistons were used and both set up .005 below 0 deck. Pretty close builds with the roller cam in the #1 engine as the biggest variable.
Other than the slight difference in displacement - is it a fair assumption to say that a roller cam is good for around 40hp/30tq in a sb?
They were not worth anything 40 yrs ago barely any better today.
03-23-2009, 09:05 PM
#11
Race Director
03-23-2009, 09:13 PM
#12
I was looking for more info about this last night, but my concern was not a hydrulic flat tappet, but a solid flat tappet vs hydraulic roller. Does anyone have any info on this? Seems that rpm potential is increased and was also thinking if building an engine entirely whay not have lifter bores increased for Ford .875 EDM lifter and use a cam with .875 lift rates. How would a solid flat tappet stack up then?
03-24-2009, 01:35 AM
#14
I was looking for more info about this last night, but my concern was not a hydrulic flat tappet, but a solid flat tappet vs hydraulic roller. Does anyone have any info on this? Seems that rpm potential is increased and was also thinking if building an engine entirely whay not have lifter bores increased for Ford .875 EDM lifter and use a cam with .875 lift rates. How would a solid flat tappet stack up then?
1500/2000 rpm higher thats its power advantage over any form of hydraulic cam, but if your not going to go past the 6000/6500 rpm there is no good reason to use one, the hydraulic roller will do better at the lower rpm levels.
