HP gains from Cam swap.

8

86bluecobra

Advanced Member

Dec 20, 2004

4,265

12

69

B.C. Canada

Jan 14, 2006

#1

• Jan 14, 2006

• #1

I posted this in 5.0L Tech but since you guys are used to flat tappet tech i thought i would ask you. Ok according to desk top dyno on my current combo if all i was to do is swao from my 274 XE flat tappet cam to a Etreme Hyd Roller 282 i would see a 20 hp jump at 4000 rpm and a 47 hp jump by 5500rpm torque would also be up with 49 more ft/lbs at 6000 rpm. Now im a little scepticle. can these really be right? the roller cam actually lifts the intake valve less then the flat tappet cam. i know there is more duration but nearly 50 hp from a cam swap? is this possible?

 

Z06killinSBF

Member

Apr 25, 2005

457

1

19

McKinney, TX

Jan 14, 2006

#2

• Jan 14, 2006

• #2

Well, the cam is bigger and the roller cam has WAY less friction. Thats a simple answer. There is actually alot different between the 2 as for the 50hp gain. As for actually testing it, maybe someone else can chime in.

 

S

steel1212

Active Member

Jun 24, 2004

1,180

0

36

Frankfort, Ky

Jan 14, 2006

#3

• Jan 14, 2006

• #3

If going to a roller why would you pic one that has less lift? I'm going to do this when I get the funds for new heads but I'm getting a roller that has considerable more lift. With a roller you can get away with it.

 

8

86bluecobra

Advanced Member

Dec 20, 2004

4,265

12

69

B.C. Canada

Jan 14, 2006

#4

• Jan 14, 2006

• #4

well a .513in and .529ex is enough cam lift for me i think. i already have troubles with vacuum for my brakes as is. and i don't really want to lose a bunch of down low torque. my heads are only good to .550 lift i believe the next cam up in comps line up is a .555 in and .576ex.

 

ashford

Member

Dec 19, 2003

485

0

16

fargo ND

Jan 14, 2006

#5

• Jan 14, 2006

• #5

the bigest advantage to a roller cam is the faster ramp rates(valves open and close faster) and most of the 280 and above grinds the valve stays open at max liftfor a short duration instead of coming down as soon as it gets there. if you were to "map out" the curve on a graph a roller cam of simalar specs would have way more area under the curve. which means the valve is opened more for the same lift and duration.

 

D

D.Hearne

New Member

Sep 29, 2000

11,730

6

0

south louisiana

Jan 14, 2006

#6

• Jan 14, 2006

• #6

86bluecobra said:

well a .513in and .529ex is enough cam lift for me i think. i already have troubles with vacuum for my brakes as is. and i don't really want to lose a bunch of down low torque. my heads are only good to .550 lift i believe the next cam up in comps line up is a .555 in and .576ex.

Click to expand...

It's not the lift that affects your idle vacuum, it's the overlap between the intake and exhaust lobes that does it. You will still have better vacuum with the roller, probably more than you've got now, even going with a roller with more lift and duration. The Z303 I've got in my 331 in the 89 Ranger has plenty of vacuum at idle for it's power brakes. (.585 lift/ 228 degrees duration @.050/ 112 degree LCA , the added lift is due to the 1.7 rockers)

 

8

86bluecobra

Advanced Member

Dec 20, 2004

4,265

12

69

B.C. Canada

Jan 14, 2006

#7

• Jan 14, 2006

• #7

yes your right but going to a bigger cam usally means going to more duration. unless you are going for a custom ground cam i guess.

 

1

10secgoal

Active Member

Dec 1, 2003

2,801

3

49

San Diego

Jan 15, 2006

#8

• Jan 15, 2006

• #8

But wat he's saying is the lift has no role in the vacuum. The vacuum is created as the piston moves down,as I am sure you know. But the overlap, when both are open, is when your vacuum drops.

 

8

86bluecobra

Advanced Member

Dec 20, 2004

4,265

12

69

B.C. Canada

Jan 15, 2006

#9

• Jan 15, 2006

• #9

yes thats true 10sec but i want to know if desk top dno is accurate in saying im going to gain 40 - 50 hp from a cam swap.