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Not interested in horsepower - Best way to increase low end torque?
I'm going to pose a question that I think is shared by some of us "more seasoned" (read: older ) drivers out here. After owning a few performance cars, I find myself a lot less interested in the "Horsepower" number; which really should be described as "Maximum Horsepower", and exists in a place way up on the rpm scale that most of us (well, me, anyway) spend very little time. In my 2012 LS3, I'm a lot more interested in the torque curve line, and I would be perfectly happy with 400 ft/lbs of torque at 4,600 rpm (as opposed to the rated 420) if I could also keep that 400 ft/lbs all the way down to 2,000 rpm (as opposed to the rated 350, which really feels more like 250). In other words, I'd rather lift the "tail" of the torque curve rather than the "head"; if the head comes up 50 ft/lbs, that's fine - just not the objective. What the horsepower rating is at 5500 rpm doesn't concern me at all. It's a date car, not a drag car.
My experience with building motors in the past indicates that - short of a $7,000 supercharger -the cam(s) can be one of the most influential components in shaping the torque curve; but it seems most people are only interested in hearing about more horsepower, so the manufacturers (rightly so) build what people say they want, and there seems to be very little technically sound advice on creating a flat torque curve from 2,000 - 5,000 rpm. I would be very interested if anyone could share their experience and/or knowledge about reshaping the bottom of an LS3 torque curve without a supercharger, and without a lot of exhaust noise - i.e. specific cams or cam profiles that really worked.
Adding lift and tightening up the stock lsa a bunch is one way. Gears is another.
Just my $.02
__________________ The Gentleman's Cruiser Shawn Miller 427 - 576RWHP 530RWT WCCH Stage 3 L92's (Still with a very small cam) Tuned by Ed Hutchings Build Thread http://ls1tech.com/forums/generation...b-c-d-e-f.html
Headers will put alot of low to mid-range in it also.
__________________ '99 SS Camaro #3789 6m hard top, crate ls6
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Have you tuned it yet? The "feels like less" is most likely torque management preventing you from getting the actual power it has onto the ground. But if torque is all you want? Get as much advance ground into the cam as PTV allows and keep the duration below 220 and the thing will tug harder down low than a freightliner
More cubic inches is a great way to increase low end torque. A 4 inch stoke with your existing LS3 heads and a custom cam would provide a significant gain.
Okay, thanks for all the input. I don't want to go too wild on this thing (boring, stoking etc) - remember, for $8,000 I can install an Edelbrock supercharger and solve the whole problem with an easy install - so I need to be able to justify the internal motor work with at least $3,000 left in my pocket. What I'm coming up with here is a set of LG Motorsports Long Tube Street headers with X-pipes, a K&N FIPK, a cam and a tune. The cam data I can accumulate is different from what I'm used to using (Harley world) - so I have a few questions regarding that:
1. What would be considered the highest lift reasonable for stock valve springs?
2. How does one calculate neccesary pushrod length?
3. Does separation angle affect IVC? Very little IVC information from the cam manufacturers out there, can I calculate it from Duration / Separation angle / Centerline?
4. How do I adjust total advance/retard of the cam - I don't see any adjustable sprockets. Custom grinding?
5. The 111 - 112 LSA cams I have heard on YouTube have noticeably rough idles - at about what point does the idle start to smooth out? 114 fairly smooth?
1: stock springs will not do
2: pushrod length checker
3: got me here
4: most people go dot to dot method
5: the higher the lsa the smoother, but a lot has to do with tune as well
Okay, after a little cam spec study, I've got the answer to 3. - the all important IVC. (still can't figure out why that's such an obscure figure in the car world) Using Duration and Centerline, we would divide Intake duration in half and distribute that before and (most important) after centerline to get IVC. For example:
Comp Cams 269LR HR12
Duration at .050" = 219*
Lobe Centerline = 107* ATDC.
219/2 = 109.5*
Distributing 109.5* before and after 107* ATDC, the intake valve will be open .050" at 2.5* BTDC and would be .050" from closing at 36.5* ABDC. Stock IVC at .050 is 43* ABDC, so this CC 269LR would boost Dynamic Compression Ratio and cold cranking pressure about 5 psi.
That's helpful in determining how a motor will behave with a particular cam in it. Separation angle must be determining overlap. I need to spin the cam around in my brain a few cycles to get a handle on that, and right now, it just TOO DARN LATE...!
I've always had success, and recommend the LPE GT11 cam for that strong, instant tq, sot, throttle response. I've had this cam in heavy auto cars, and recommended based on my experience with it. Don't let it's low duration fool you, it's aggressive but IMO will deliver what u are looking for. It also a profile suited for rectangle port heads, although originally designed for cathedral port heads. It is extremely responsive in 6.0 motors with common scr.
I've always had success, and recommend the LPE GT11 cam for that strong, instant tq, sot, throttle response. I've had this cam in heavy auto cars, and recommended based on my experience with it. Don't let it's low duration fool you, it's aggressive but IMO will deliver what u are looking for. It also a profile suited for rectangle port heads, although originally designed for cathedral port heads. It is extremely responsive in 6.0 motors with common scr.
NemeSS;
That looks like a good cam - a lot of lift, short duration. And no, I'm not fooled by short duration, and I'm not another one of these guys who think that small numbers = bad, large numbers = good. My experience with cam installations is that shorter duration, higher lift cams with earlier intake closing (to a point) "feel" a lot more powerful in normal day to day driving - although they also sign off earlier in the rpm band. Which I'm good with - I don't want to have to downshift two gears every time I pass a car.
I talked to Ryan at Lingenfelter, and answered two more questions: The LSA on this cam is 118. When I listened to a YouTube video of this cam installed in an LS3, it sounded good - low and throaty but not choppy (which is what I want) A lot of guys are really pushing the limits with these 111 - 112 LSA cams, but I'd rather stay a little closer to the stock LSA. Using the Wallace Racing calculator, we get an IVC of 45.5 - which won't improve CCP that much.
The next important question answered is the limits of the stock springs, which Ryan said was about .580 - not much higher than the stock cam lift of .551.
More pieces fall in to place. Thanks for the help and good info.
Not interested in horsepower - Best way to increase low end torque? 
) drivers out here. After owning a few performance cars, I find myself a lot less interested in the "Horsepower" number; which really should be described as "Maximum Horsepower", and exists in a place way up on the rpm scale that most of us (well, me, anyway) spend very little time. In my 2012 LS3, I'm a lot more interested in the torque curve line, and I would be perfectly happy with 400 ft/lbs of torque at 4,600 rpm (as opposed to the rated 420) if I could also keep that 400 ft/lbs all the way down to 2,000 rpm (as opposed to the rated 350, which really feels more like 250). In other words, I'd rather lift the "tail" of the torque curve rather than the "head"; if the head comes up 50 ft/lbs, that's fine - just not the objective. What the horsepower rating is at 5500 rpm doesn't concern me at all. It's a date car, not a drag car.
