Custom Cam for Low-End Torque?
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From: Herndon, VA
Custom Cam for Low-End Torque? About a month ago I asked about designing a custom cam for big low-end torque, and I suggested something like 216/230 58x/57x 115lsa.
The suggestion was shot down pretty quick because of the split being way too big. But a lot of discussion lately in cam threads about low-end torque have included designs that seem similar.
What's wrong with the following strategy for producing more low-end torque?
-Low IV duration 214-218
-Big EV duration 228-232
-Decent Lift 57x or 58x (is there a formula to choose lift based on duration?)
-High Ramp Rate (ADV Duration @ .004 - duration @ .050 = 50's)
-Low LSA (110+4, a change from my original suggestion of 115, based on discussion in the previous thread, etc.)
-ICL (can someone help me with the math to achieve overlap of 0 to plus 4, and which would be best)
I want a rough idle. After being shot down before for the big split, I searched the sponsors for cams that I thought I'd like, and the F13 is what I picked. I had some question about drivability in traffic, but most seem to think a good tune can make any cam drivable... I think I'll be really happy with the F13, but it's not exactly what I originally wanted.
So, is the split really too big in the custom cam design, and if so where are the fatal flaws in my reasoning? (if the list isn't too long to post...)
I've already got most bolt-ons, and this is a street car that will only occasionally see the track, but I have a lot of mustang owners to humiliate.
Thanks for your help and indulgence of the un-worthy...
The suggestion was shot down pretty quick because of the split being way too big. But a lot of discussion lately in cam threads about low-end torque have included designs that seem similar.
What's wrong with the following strategy for producing more low-end torque?
-Low IV duration 214-218
-Big EV duration 228-232
-Decent Lift 57x or 58x (is there a formula to choose lift based on duration?)
-High Ramp Rate (ADV Duration @ .004 - duration @ .050 = 50's)
-Low LSA (110+4, a change from my original suggestion of 115, based on discussion in the previous thread, etc.)
-ICL (can someone help me with the math to achieve overlap of 0 to plus 4, and which would be best)
I want a rough idle. After being shot down before for the big split, I searched the sponsors for cams that I thought I'd like, and the F13 is what I picked. I had some question about drivability in traffic, but most seem to think a good tune can make any cam drivable... I think I'll be really happy with the F13, but it's not exactly what I originally wanted.
So, is the split really too big in the custom cam design, and if so where are the fatal flaws in my reasoning? (if the list isn't too long to post...)
I've already got most bolt-ons, and this is a street car that will only occasionally see the track, but I have a lot of mustang owners to humiliate.
Thanks for your help and indulgence of the un-worthy...
Last edited by FUN LS1; Aug 12, 2005 at 11:13 AM.
Launching!
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From: PA
I have the X1, reverse split. Look at my torque before and after the cam. I have highlighted to differences. This cam builts tons of torque fast and in the driveable power curve. At least it did for me. The car is an 03 Z06 with stock heads. The cam peaked out at 44 HP and 41 torque increase.
230 228
112 LSA
.592 .571 lift
230 228
112 LSA
.592 .571 lift
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From: BFE
Joined: Nov 2003
Posts: 6,216
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From: Wichita KS / Rancho San Diego
The CheaTR cam has proven the viability of the big split but tends to make it's best gains on the top end; the GM performance cams (hotcam, ASA) have pretty big splits with tighter LSA and produce good low-end torque. The issue is increasing overlap as that LSA gets tighter on a big split cam. But if you want a rough idle, that's the way to go. I think your concept is viable, but it'll be rough at low rpms. You'll just have to do some serious tuning to get good driveablility from it.
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From: Herndon, VA
Originally Posted by PREDATOR-Z
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Verdad Gallardo Thread Starter
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From: Herndon, VA
Originally Posted by RevGTO
The CheaTR cam has proven the viability of the big split but tends to make it's best gains on the top end; the GM performance cams (hotcam, ASA) have pretty big splits with tighter LSA and produce good low-end torque. The issue is increasing overlap as that LSA gets tighter on a big split cam. But if you want a rough idle, that's the way to go. I think your concept is viable, but it'll be rough at low rpms. You'll just have to do some serious tuning to get good driveablility from it.
The 220/220 cam I am changing next is so strong down low, I'm ditching it for a 224/228 to move the torque curve up a little bit. Nitto's and I just spin if I get on it much at all. I love the cam, but, the short 1st gear (A4) just doesn't need that much torque down so low. If you have shorter gears ... maybe 3:23's ... IMHO a 220/220 is perfect.
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From: BFE
Originally Posted by JEB99TA
The 220/220 cam I am changing next is so strong down low, I'm ditching it for a 224/228 to move the torque curve up a little bit. Nitto's and I just spin if I get on it much at all. I love the cam, but, the short 1st gear (A4) just doesn't need that much torque down so low. If you have shorter gears ... maybe 3:23's ... IMHO a 220/220 is perfect.
Probably would work well with the 100 dry shot I'm thinking about doing, but, when I do the DP 100 wet shot, then upgrade to the 150.175 you rtecommended, well, retarding the timing 4 degrees won't measure up. I'll need the cam upgrade for my long-term goals. 220/220 is going up for sale quick man. Mark, you're the man, man. I'll let you know when my motor is done with the forging. I'll prob need your help with my setup. You know yuor stuff dude and you've help a lot of folks here ... whne you coming back to the states dude?
Probably would work well with the 100 dry shot I'm thinking about doing, but, when I do the DP 100 wet shot, then upgrade to the 150/175 you recommended, well, retarding the timing 4 degrees won't measure up. I'll need the cam upgrade for my long-term goals. 220/220 is going up for sale quick man. Mark, you're the man, man. I'll let you know when my motor is done with the forging. I'll prob need your help with my setup. You know yuor stuff dude and you've help a lot of folks here ... whne you coming back to the states dude?
I'm running a 216/224 VHP/Crane on Crane 1.8 rockers .590 lift with 115 lsa, AFR 205's 62cc, 3.910 bore .040 cometics and car is unbelievable now. Don't be deceived with small .050 duration, valve events more similar to a cam with 6-8* more duration.
