Comp Cam XR265HR-15 LSA 115 or ? for a 5.3l
01-04-2009, 09:44 PM
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Comp Cam XR265HR-15 LSA 115 or ? for a 5.3l
Hey Guys,
I am putting a 2005 5.3l LM7 in a 1995 Silverado RCBS, cat back Flowmaster and a CAI. I'll be having Rick at Synergy so a tune once it's up and running. I plan on using the stock 2005 4L60e torque converter and the truck curently has 3.42:1 gears. The truck won't be used for any towing but is driven around town a lot and I would like to maintain as much low end torque as possible. I'm going to order a Comp Cams XR265HR-15 212/218 55x/56x but I was considering having Comp Cams grind it on a 112 or 114 LSA instead of the 115 LSA to bring the power band down to a lower RPM range. I have heard this cam passes the CA smog checks and I don't think the lower LSA should have any drastic effect on that issue.
Any recommendations?
Thanks, Rick
I am putting a 2005 5.3l LM7 in a 1995 Silverado RCBS, cat back Flowmaster and a CAI. I'll be having Rick at Synergy so a tune once it's up and running. I plan on using the stock 2005 4L60e torque converter and the truck curently has 3.42:1 gears. The truck won't be used for any towing but is driven around town a lot and I would like to maintain as much low end torque as possible. I'm going to order a Comp Cams XR265HR-15 212/218 55x/56x but I was considering having Comp Cams grind it on a 112 or 114 LSA instead of the 115 LSA to bring the power band down to a lower RPM range. I have heard this cam passes the CA smog checks and I don't think the lower LSA should have any drastic effect on that issue.
Any recommendations?
Thanks, Rick
01-04-2009, 10:40 PM
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You can find the actual off-the-shelf cam for $200-300 new a lot of places. A custom grind will cost no less than $350, usually more straight from Comp Cams. I don't think the difference between the 115 +0 version and the proposed 112 +0 version would yield gains worth the extra cost.
However, the theory is dead on. Grinding it on a straight up 112 +0 would bring peak torque down a little, raise cylinder pressure and not bleed off as much compression compared to the off-the-shelf version. If it were my camshaft and money wasn't a factor, I'd grind the intake center line on a 110 with 2 degrees of advance built in, making the lobe separation 112 then instead of straight up with no advance. Idle quality will remain closely the same, but you will make even more cylinder pressure, and therefore torque. Mill the heads just slightly from 61.15cc to 59cc and you'd have one monster 5.3L down low, it'd probably feel like a 6.0L even at a modest 9.7:1 compression ratio.
However, the theory is dead on. Grinding it on a straight up 112 +0 would bring peak torque down a little, raise cylinder pressure and not bleed off as much compression compared to the off-the-shelf version. If it were my camshaft and money wasn't a factor, I'd grind the intake center line on a 110 with 2 degrees of advance built in, making the lobe separation 112 then instead of straight up with no advance. Idle quality will remain closely the same, but you will make even more cylinder pressure, and therefore torque. Mill the heads just slightly from 61.15cc to 59cc and you'd have one monster 5.3L down low, it'd probably feel like a 6.0L even at a modest 9.7:1 compression ratio.
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01-05-2009, 08:20 AM
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I plan on it. I just like to get some feedback first before I hit him up about stuff. He's making his living at our hobby so I try not to bug him too much! I bet he could stay on the computer 24/7 if he answered everything that is asked of him.
I wish I had 3:42's in my Denali. I'd love to feel it spool up under that kind of load. I blast through first gear so quickly that it would be great to have it hold longer. I sure there is a 4L80e in my future so that will eat some of those 4:11's.
The price difference isn't too bad between the Comp customs and their off-the-shelf cams. I like the idea of the grinding it on a 112 to increase the cyclinder pressure. I think it will make a more streetable ride without losing too much of the top end. It's my Father-in-laws truck so I couldn't convince him to put in a mild (ie:TBTC) stall so I didn't want to make it a dog around town (where he does most of his driving).
I considered milling the stock heads to bump the compression a little but it's not cost effective when you factor in the head gasket and tty bolts. I'd rather see how he likes it and keep an eye out for some 243's down the road...
Rick
I wish I had 3:42's in my Denali. I'd love to feel it spool up under that kind of load. I blast through first gear so quickly that it would be great to have it hold longer. I sure there is a 4L80e in my future so that will eat some of those 4:11's.
You can find the actual off-the-shelf cam for $200-300 new a lot of places. A custom grind will cost no less than $350, usually more straight from Comp Cams. I don't think the difference between the 115 +0 version and the proposed 112 +0 version would yield gains worth the extra cost.
However, the theory is dead on. Grinding it on a straight up 112 +0 would bring peak torque down a little, raise cylinder pressure and not bleed off as much compression compared to the off-the-shelf version. If it were my camshaft and money wasn't a factor, I'd grind the intake center line on a 110 with 2 degrees of advance built in, making the lobe separation 112 then instead of straight up with no advance. Idle quality will remain closely the same, but you will make even more cylinder pressure, and therefore torque. Mill the heads just slightly from 61.15cc to 59cc and you'd have one monster 5.3L down low, it'd probably feel like a 6.0L even at a modest 9.7:1 compression ratio.
However, the theory is dead on. Grinding it on a straight up 112 +0 would bring peak torque down a little, raise cylinder pressure and not bleed off as much compression compared to the off-the-shelf version. If it were my camshaft and money wasn't a factor, I'd grind the intake center line on a 110 with 2 degrees of advance built in, making the lobe separation 112 then instead of straight up with no advance. Idle quality will remain closely the same, but you will make even more cylinder pressure, and therefore torque. Mill the heads just slightly from 61.15cc to 59cc and you'd have one monster 5.3L down low, it'd probably feel like a 6.0L even at a modest 9.7:1 compression ratio.
I considered milling the stock heads to bump the compression a little but it's not cost effective when you factor in the head gasket and tty bolts. I'd rather see how he likes it and keep an eye out for some 243's down the road...
Rick
01-05-2009, 09:02 AM
#9
I've got the lower lift version with the 114+4 LSA... I do not have a TC and its a well decent cam for the stock TC. I don't feel I would need a TC with this cam unless I was dragging the strip.. around town its great, almost stock like and with the low lift version it keeps pulling all the way to the redline, im sure the higher lift verison would be even better!!
for a starter cam its great! I just got used to my driving round so I'm stepping up to a 220 .56x cam.. will post back with results once i install the cam and see if it was worth it
for a starter cam its great! I just got used to my driving round so I'm stepping up to a 220 .56x cam.. will post back with results once i install the cam and see if it was worth it
01-05-2009, 01:39 PM
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You can find the actual off-the-shelf cam for $200-300 new a lot of places. A custom grind will cost no less than $350, usually more straight from Comp Cams. I don't think the difference between the 115 +0 version and the proposed 112 +0 version would yield gains worth the extra cost.
However, the theory is dead on. Grinding it on a straight up 112 +0 would bring peak torque down a little, raise cylinder pressure and not bleed off as much compression compared to the off-the-shelf version. If it were my camshaft and money wasn't a factor, I'd grind the intake center line on a 110 with 2 degrees of advance built in, making the lobe separation 112 then instead of straight up with no advance. Idle quality will remain closely the same, but you will make even more cylinder pressure, and therefore torque. Mill the heads just slightly from 61.15cc to 59cc and you'd have one monster 5.3L down low, it'd probably feel like a 6.0L even at a modest 9.7:1 compression ratio.
However, the theory is dead on. Grinding it on a straight up 112 +0 would bring peak torque down a little, raise cylinder pressure and not bleed off as much compression compared to the off-the-shelf version. If it were my camshaft and money wasn't a factor, I'd grind the intake center line on a 110 with 2 degrees of advance built in, making the lobe separation 112 then instead of straight up with no advance. Idle quality will remain closely the same, but you will make even more cylinder pressure, and therefore torque. Mill the heads just slightly from 61.15cc to 59cc and you'd have one monster 5.3L down low, it'd probably feel like a 6.0L even at a modest 9.7:1 compression ratio.
