comp cams question

[rivercitypony]

I have listed the Comp specs for the 127300 and 127400 cams (see below). Can someone please explain why the 127400s are supposed to be the better n/a cam? BTW, Comp rep. emailed me that the 127400s are the biggest cam they recommend for stock heads. Thanks in advance for any input.

127300 cams
Duration:
Intake 261
Exhaust 278
Lobe Seperation 115 degrees
Intake Centerline 101 degrees
Valve Lift:
Intake 0.49
Exhaust 0.48

127400 cams
Duration:
Intake 256
Exhaust 267
Lobe Seperation Angle: 112
Intake Centerline: 102
Valve Lift:
Intake 0.523
Exhaust 0.538

 

[101fng]

i'm not the most knowledegable on cams, but if i'm not mistaken the tighter LSA and higher lift shifts the powerband towards the topend

 

[drive_55_not]

i'm not the most knowledegable on cams, but if i'm not mistaken the tighter LSA and higher lift shifts the powerband towards the topend

Nope,, Tighter LSA moves power band to the low end, will raise cylinder pressures and creates more of a peak in the power band. Tighter LSA will also cause a drop in idle vacuum so drive-ability could be an issue.

However 112 isn't that tight, Really aggressive NA cam's will have LSA's of 106/107/108. Drive-ability would suffer with something that tight but it would sound like a pro-mod.

A wider LSA will have a flatter torque curve.

Since the OP is already running the 300's, I doubt you'd gain more than 10hp going with the 400's. The 400's would have more rumble at idle.


.

 

[niner555]

I have listed the Comp specs for the 127300 and 127400 cams (see below). Can someone please explain why the 127400s are supposed to be the better n/a cam? BTW, Comp rep. emailed me that the 127400s are the biggest cam they recommend for stock heads. Thanks in advance for any input.

127300 cams
Duration:
Intake 261
Exhaust 278
Lobe Seperation 115 degrees
Intake Centerline 101 degrees
Valve Lift:
Intake 0.49
Exhaust 0.48

127400 cams
Duration:
Intake 256
Exhaust 267
Lobe Seperation Angle: 112
Intake Centerline: 102
Valve Lift:
Intake 0.523
Exhaust 0.538

I would disagree with the COMP rep. Those two cam set part #'s are from two different cam series and not really a fair comparison. The 127400 is the "stage 1" cam that requires a phaser limiter and the 127300 is COMP's "stage 2" non-phaser limiter cam.

The more accurate comparison is the 127300 vs. the 127500. Having used both (with the 127500's currently installed), go with the 127500's. They have a really nice "cammed" idle, lose no bottom end tq. and make about 15 more HP up top than the 127300's.

 

[AutoXRacer]

Damn, wish I would have known that before I had my engine built...
I got the 127300s...

 

[drive_55_not]

I would disagree with the COMP rep. Those two cam set part #'s are from two different cam series and not really a fair comparison. The 127400 is the "stage 1" cam that requires a phaser limiter and the 127300 is COMP's "stage 2" non-phaser limiter cam.

The more accurate comparison is the 127300 vs. the 127500. Having used both (with the 127500's currently installed), go with the 127500's. They have a really nice "cammed" idle, lose no bottom end tq. and make about 15 more HP up top than the 127300's.

I'd agree the 500's would be a better choice since he'd need limiters or lockouts anyway.

Comp even posted a video with the 500's showing they picked up 37hp on a (guessing it's stock) 3v.

http://www.youtube.com/watch?v=8VFjfFfzr_w

I installed a set of 300's and picked up 22hp, so I'd say 15 would be right.


.

 

[rivercitypony]

I would disagree with the COMP rep. Those two cam set part #'s are from two different cam series and not really a fair comparison. The 127400 is the "stage 1" cam that requires a phaser limiter and the 127300 is COMP's "stage 2" non-phaser limiter cam.

The more accurate comparison is the 127300 vs. the 127500. Having used both (with the 127500's currently installed), go with the 127500's. They have a really nice "cammed" idle, lose no bottom end tq. and make about 15 more HP up top than the 127300's.

Great information from you guys. I should have mentioned that I already have limiters with my 127300s. My tuner insisted on them. Also, how is low-end driveability with the 127500s, and do they need limiters or lockouts? As I'm staying N/A for awhile, I'd be o.k. with a 15 horsepower increase and no loss of torque.

 

[JeremyH]

Keep the 127300's, great all around mild cam. Are you going for a dyno numbers or driveability?

 

[101fng]

Great information from you guys. I should have mentioned that I already have limiters with my 127300s. My tuner insisted on them. Also, how is low-end driveability with the 127500s, and do they need limiters or lockouts? As I'm staying N/A for awhile, I'd be o.k. with a 15 horsepower increase and no loss of torque.

i love my 500's. i might have lost some low end (at least it feels like it), but 4.10's help hide it and it hasn't really affected drivability. the top end is awesome though as well as the idle. i can't speak for the 300's though.