Before you dismiss reverse split cams...
Thread Starter
Joined: Nov 2001
Posts: 8,246
Likes: 34
From: Victoria, TX
Before you dismiss reverse split cams... remember, some of the most popular LS1 cams are reverse splits (more intake duration than exhaust duration) at some point in their function. Take the FMS F-13. According to the Cam Doctor it looks like this:
___________________________________________ 0.006 0.050 0.200
Intake Duration - ID_______________________ 281 230 150 F-13 INTAKE
Exhaust Duration - ED______________________ 285 232 148 F-13 EXHAUST
Lobe Center Angle - LCA (also known as LSA) 112 112 112
Intake Centerline - ICL____________________ 108 108 108
Intake Valve opens - IVO___________________ 32.5 7 -33 BTDC (- indicates ATDC)
Intake Valve closes - IVC__________________ 68.5 43 3 ABDC
Exhaust Valve Opens - EVO__________________ 78.5 52 10 BBDC
Exhaust Valve Closes - EVC_________________ 26.5 0 -42 ATDC (- indicates BTDC)
Exhaust Centerline - ECL___________________ 116 116 116
Overlap____________________________________ 59 7 -75 degrees
Notice how there's more intake duration at .200" lift than exhaust? And since the heads are most effective above .200" lift, I'd have to say reverse split cams shouldn't be dismissed as being ineffective too quickly. Funny how so many on this site get caught up in duration at .050" only and fail to look at the big picture.
FWIW, my Thunder Racing TRak cam is also a reverse split cam at .200" (157/155). Works for me!
___________________________________________ 0.006 0.050 0.200
Intake Duration - ID_______________________ 281 230 150 F-13 INTAKE
Exhaust Duration - ED______________________ 285 232 148 F-13 EXHAUST
Lobe Center Angle - LCA (also known as LSA) 112 112 112
Intake Centerline - ICL____________________ 108 108 108
Intake Valve opens - IVO___________________ 32.5 7 -33 BTDC (- indicates ATDC)
Intake Valve closes - IVC__________________ 68.5 43 3 ABDC
Exhaust Valve Opens - EVO__________________ 78.5 52 10 BBDC
Exhaust Valve Closes - EVC_________________ 26.5 0 -42 ATDC (- indicates BTDC)
Exhaust Centerline - ECL___________________ 116 116 116
Overlap____________________________________ 59 7 -75 degrees
Notice how there's more intake duration at .200" lift than exhaust? And since the heads are most effective above .200" lift, I'd have to say reverse split cams shouldn't be dismissed as being ineffective too quickly. Funny how so many on this site get caught up in duration at .050" only and fail to look at the big picture.
FWIW, my Thunder Racing TRak cam is also a reverse split cam at .200" (157/155). Works for me!
__________________
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
I had the MTI X1 (230/227) in my last SS, and it pulled 10 rwhp higher than any other heads/cam combo at the same dyno day....and I did it with cats on the car and a factory 3" catback. There were quite a few cars that day with huge loping cams and offroads and cutouts, etc...
Bigger isn't always better. Louder isn't faster. Reverse splits work great.
Bigger isn't always better. Louder isn't faster. Reverse splits work great.
TECH Resident
Joined: Sep 2003
Posts: 848
Likes: 1
From: Working in the shop 24/7
Originally Posted by Patrick G
remember, some of the most popular LS1 cams are reverse splits (more intake duration than exhaust duration) at some point in their function. Take the FMS F-13. According to the Cam Doctor it looks like this:
___________________________________________ 0.006 0.050 0.200
Intake Duration - ID_______________________ 281 230 150 F-13 INTAKE
Exhaust Duration - ED______________________ 285 232 148 F-13 EXHAUST
Lobe Center Angle - LCA (also known as LSA) 112 112 112
Intake Centerline - ICL____________________ 108 108 108
Intake Valve opens - IVO___________________ 32.5 7 -33 BTDC (- indicates ATDC)
Intake Valve closes - IVC__________________ 68.5 43 3 ABDC
Exhaust Valve Opens - EVO__________________ 78.5 52 10 BBDC
Exhaust Valve Closes - EVC_________________ 26.5 0 -42 ATDC (- indicates BTDC)
Exhaust Centerline - ECL___________________ 116 116 116
Overlap____________________________________ 59 7 -75 degrees
Notice how there's more intake duration at .200" lift than exhaust? And since the heads are most effective above .200" lift, I'd have to say reverse split cams shouldn't be dismissed as being ineffective too quickly. Funny how so many on this site get caught up in duration at .050" only and fail to look at the big picture.
FWIW, my Thunder Racing TRak cam is also a reverse split cam at .200" (157/155). Works for me!
___________________________________________ 0.006 0.050 0.200
Intake Duration - ID_______________________ 281 230 150 F-13 INTAKE
Exhaust Duration - ED______________________ 285 232 148 F-13 EXHAUST
Lobe Center Angle - LCA (also known as LSA) 112 112 112
Intake Centerline - ICL____________________ 108 108 108
Intake Valve opens - IVO___________________ 32.5 7 -33 BTDC (- indicates ATDC)
Intake Valve closes - IVC__________________ 68.5 43 3 ABDC
Exhaust Valve Opens - EVO__________________ 78.5 52 10 BBDC
Exhaust Valve Closes - EVC_________________ 26.5 0 -42 ATDC (- indicates BTDC)
Exhaust Centerline - ECL___________________ 116 116 116
Overlap____________________________________ 59 7 -75 degrees
Notice how there's more intake duration at .200" lift than exhaust? And since the heads are most effective above .200" lift, I'd have to say reverse split cams shouldn't be dismissed as being ineffective too quickly. Funny how so many on this site get caught up in duration at .050" only and fail to look at the big picture.
FWIW, my Thunder Racing TRak cam is also a reverse split cam at .200" (157/155). Works for me!
Ed
Trending Topics
Am I right in assuming that a reverse split cam will not give up much if any low end (idle-3,000 rpm) torque? I like the idea of a custom 234°/228° with say .598"/.589"ish lifts on a 111° IC +3° (108° IC) 
. Kind of right between the TR 230 and 236 reverse cams with more lift .
. Kind of right between the TR 230 and 236 reverse cams with more lift . LS1 Tech Stories
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nice info. not to be a stickler, but if you use the "code" tags you can get nicer looking charts that are eaiser to follow (keeps spacing of all characters equal):
tried to make it clearer patrick. thanks for your research also!
Code:
A B C D E 1 2 3 4 5 a b c d e
Code:
___________________________________________ 0.006 0.050 0.200 Intake Duration - ID_______________________ 281 230 150 F-13 INTAKE Exhaust Duration - ED______________________ 285 232 148 F-13 EXHAUST Lobe Center Angle - LCA (also known as LSA) 112 112 112 Intake Centerline - ICL____________________ 108 108 108 Intake Valve opens - IVO___________________ 32.5 7 -33 BTDC (- indicates ATDC) Intake Valve closes - IVC__________________ 68.5 43 3 ABDC Exhaust Valve Opens - EVO__________________ 78.5 52 10 BBDC Exhaust Valve Closes - EVC_________________ 26.5 0 -42 ATDC (- indicates BTDC) Exhaust Centerline - ECL___________________ 116 116 116 Overlap____________________________________ 59 7 -75 degrees
Last edited by Grimes; Sep 6, 2005 at 11:33 AM.
Our plastic OEM LS6 and PORTED FAST intakes simply will not flow enough air to make the AFR 205 head perform to its full potential much less the AFR 225's potential. So using reverse split cams with our restricted intake sounds good on paper any way.
Last edited by gollum; Sep 6, 2005 at 04:05 PM.
Originally Posted by gollum
This affordable $279.50 Patriot cam cam looks very interesting to me.
232/230@.050, 110 lsa .580 lift
232/230@.050, 110 lsa .580 lift
Originally Posted by gomer
I did some of the pre-production testing on that cam. I'll look for the dyno graphs from it. I do remember it being a choppy idling sob.. lol.
Thread Starter
Joined: Nov 2001
Posts: 8,246
Likes: 34
From: Victoria, TX
Originally Posted by Beast96Z
It all depends on the set-up. One must also look at the complete profile of his set-up before determing a givin lobe.
__________________
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
Do any of u cam professors race your cars 
I've been 10's ON MOTOR with an off the shelf TR 224 no big cam profiles,secret under the curve horse manure,lobe design bs....Just an off the shelf TR cam
I've been 10's ON MOTOR with an off the shelf TR 224 no big cam profiles,secret under the curve horse manure,lobe design bs....Just an off the shelf TR cam
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
Originally Posted by JS
Do any of u cam professors race your cars
I've been 10's ON MOTOR with an off the shelf TR 224 no big cam profiles,secret under the curve horse manure,lobe design bs....Just an off the shelf TR cam
I've been 10's ON MOTOR with an off the shelf TR 224 no big cam profiles,secret under the curve horse manure,lobe design bs....Just an off the shelf TR cam
A 3150 pound car with an A4 and a 4400 stall?
