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differance between 112 over 112+4 lsa
stupid question and im not goin to buy the one that sounds better ok my buddy has a 224/581 on a 112+4 in a 05 5.3 LTs ory yada yada but my question is the truck sounds very timid at idle ive heard a 220/581 on a 112 and it sounded meaner at idle does the 112+4 mean it has 4 degrees advance ground into the cam and is that the reason it sounds timid ?
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The 4 degrees advance bring the power band in at a lower rpm! They usually have a choppier idle.
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Let’s see if I can say this where it make sense. A cam ground on an 112cl is a 112 and a cam ground on an 114cl is a 114, no matter how much or little advance is ground in. Think of it as the cam manufacturer is taking the cam and twisting the installation the same as you would by using a multi-keyed timing chain. They are just doing it in the manufacturing process so that you can just basically line up the cam dot-to-dot. That doesn’t mean the cam should not be degreed in, but that is the general idea. As has been mentioned a hundred times if not more, having the advance ground in moves the power-band down which generally helps in a lot of applications (especially trucks) and probably why everyone swears by the + cams. However one could get the same end result by spec-ing out the correct cam to begin with and or using an adjustable timing chain.
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Ok -- a cam ground on a 112 ICL with an LSA of 112 has 0* advance or retard (let's call this a 'true 112' even though that's a really bad name). A cam on a 112 ICL and a 116 LSA has 4* advance, which is why the true 112 sounds choppier. A cam on an 108 ICL and a 112 LSA is still 4* advanced.
By timing your cam (or using an adjustible timing set up), you can change the ICL of the cam -- say you take your 112 ICL cam and you install it 4* advanced-- thats now a 108 ICL, etc. **THESE DAYS, installing dot-on-dot is teh pwn IMO** ((Edit: but this does NOT change the LSA, because a change to cam timing on install changes both ICL and ECL)) Advancing the cam builds more low and mid range torque and lowers the power band (retarding builds more high end torque and raises the power band). A tighter lsa (meaning lower number) moves torque lower on the power band and increases max torque, while narrowing the power band, building higher cylinder pressure. Because the lsa is tighter, there is generally more overlap, which means rougher idle, lower idle vacuum, decrease p to v clearence, etc. Wider lsas raise the torque to higher rpm, reduces max torque, while broadening the powerband, reducing cylinder pressures, decreasing overlap, increasing p to v, etc. So the ultimate answer to your question is: Yes, that cam has 4* advance ground in and that's why it's tamer at idle. |
Originally Posted by TurboBerserker
(Post 4231567)
Ok -- a cam ground on a 112 ICL with an LSA of 112 has 0* advance or retard (let's call this a 'true 112' even though that's a really bad name). A cam on a 112 ICL and a 116 LSA has 4* advance, which is why the true 112 sounds choppier. A cam on an 108 ICL and a 112 LSA is still 4* advanced.
By timing your cam (or using an adjustible timing set up), you can change the ICL of the cam -- say you take your 112 ICL cam and you install it 4* retarded -- thats now a 108 ICL, etc. **THESE DAYS, installing dot-on-dot is teh pwn IMO** Advancing the cam builds more low and mid range torque and lowers the power band (retarding builds more high end torque and raises the power band). A tighter lsa (meaning lower number) moves torque lower on the power band and increases max torque, while narrowing the power band, building higher cylinder pressure. Because the lsa is tighter, there is generally more overlap, which means rougher idle, lower idle vacuum, decrease p to v clearence, etc. Wider lsas raise the torque to higher rpm, reduces max torque, while broadening the powerband, reducing cylinder pressures, decreasing overlap, increasing p to v, etc. So the ultimate answer to your question is: Yes, your cam has 4* advanced ground in, and yes that's why it's tamer at idle. |
Good info
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Originally Posted by TurboBerserker
(Post 4231567)
Ok -- a cam ground on a 112 ICL with an LSA of 112 has 0* advance or retard (let's call this a 'true 112' even though that's a really bad name). A cam on a 112 ICL and a 116 LSA has 4* advance, which is why the true 112 sounds choppier. A cam on an 108 ICL and a 112 LSA is still 4* advanced.
By timing your cam (or using an adjustible timing set up), you can change the ICL of the cam -- say you take your 112 ICL cam and you install it 4* retarded -- thats now a 108 ICL, etc. **THESE DAYS, installing dot-on-dot is teh pwn IMO** Advancing the cam builds more low and mid range torque and lowers the power band (retarding builds more high end torque and raises the power band). A tighter lsa (meaning lower number) moves torque lower on the power band and increases max torque, while narrowing the power band, building higher cylinder pressure. Because the lsa is tighter, there is generally more overlap, which means rougher idle, lower idle vacuum, decrease p to v clearence, etc. Wider lsas raise the torque to higher rpm, reduces max torque, while broadening the powerband, reducing cylinder pressures, decreasing overlap, increasing p to v, etc. So the ultimate answer to your question is: Yes, your cam has 4* advanced ground in, and yes that's why it's tamer at idle. |
Originally Posted by TurboBerserker
(Post 4231567)
Ok -- a cam ground on a 112 ICL with an LSA of 112 has 0* advance or retard (let's call this a 'true 112' even though that's a really bad name). A cam on a 112 ICL and a 116 LSA has 4* advance, which is why the true 112 sounds choppier. A cam on an 108 ICL and a 112 LSA is still 4* advanced.
By timing your cam (or using an adjustible timing set up), you can change the ICL of the cam -- say you take your 112 ICL cam and you install it 4* retarded -- thats now a 108 ICL, etc. **THESE DAYS, installing dot-on-dot is teh pwn IMO** Advancing the cam builds more low and mid range torque and lowers the power band (retarding builds more high end torque and raises the power band). A tighter lsa (meaning lower number) moves torque lower on the power band and increases max torque, while narrowing the power band, building higher cylinder pressure. Because the lsa is tighter, there is generally more overlap, which means rougher idle, lower idle vacuum, decrease p to v clearence, etc. Wider lsas raise the torque to higher rpm, reduces max torque, while broadening the powerband, reducing cylinder pressures, decreasing overlap, increasing p to v, etc. So the ultimate answer to your question is: Yes, your cam is 4* advanced (and hence has a higher lsa than the true 112), and yes that's why it's tamer at idle. |
Erik you're so awesome :kiss:
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so say 224/224 cam with a 112 compared to a 224/224 cam with a 112+2 the 112 will have a choppy idle and lower power band and the 112+2 will not be so choppy and high power band??? did i get that right? makin sure i understand this right so i can choose my cam soon
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