LTX and LSXPutting LT1's, LS1's, and their variants into Third Gens is becoming more popular. This board is for those who are doing and have done the swaps so they can discuss all of their technical aspects, including repairs, swap info, and performance upgrades.
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Also!! While the LM7 will be a major friggen upgrade from the factory L03 that currently resides I will need to build the LM7 for low end torque. It has recently been brought to my attention that the LM7 is a little lacking in low end torque.
Also!! ..again.. I will be putting a mild bore/stroke combo into engine.
i think you should go with the smaller one. and unless you are going to do some headwork,big cam, and a real good flowing exhaust i think either will hurt you. the lm7 does not flow like the ls1 series engines.
cool, thanks for the reply. as for flow numbers i have been bouncing around between air flow research, trick flow and racing head service. so the super cool intake would have some super cool (and well flowing) cylinder heads to go along with it.
My Lm7 totally kills the 2 LO3s I had. Any stock LM7 will give you over 290 ft-lbs at just 1500 rpm, and builds to over 325 by 4000. Compare that to the LO3 making peak torque of 255 ft-lbs at 2400 rpm, it's no contest. The LM7 is only lacking when compared to larger engines. The FAST 102 is only for LS3/L92 heads, it won't work on any heads that you can bolt onto a stock-bore LM7. The 92 will work for you, but you can probably find a used FAST 90 for half the money. Even with cam and heads, an LM7 won't miss those last 2 mm. The wisest thing to do for better flowing heads is a pair of CNC-ported 5.3 heads from Total Engine Airflow. They offer several stages, but stage 1.5 is the most flow for the least dough, stage 2 is past the point of diminishing returns.
I can't give you an exact number, but I know 570 HP without boost or nitrous, maybe more on a wilder build. A used LS6 intake would be best for your stock heads, but why buy it when it can't keep up with better-flowing heads, such as TEA-ported heads?
my goal is for 500 foot lbs at the rears. not a big fan of keeping the stock cylinder heads. that is why i have been lookin at companies like RHS and AFR.
I have not ever heard of TEA until now. Ill hafta check em out.
To get 500 ft-lbs at the rear tires, you will have to go with an old-school big block, or a power adder like nitrous or turbocharging. Keep in mind that a T56 and a 12-bolt will still eat 13% of what the emngine makes, assuming you use good synthetic lubricants in the trans and axle.
Why spend $2400 on a new pair of heads, as good as the AFRs are, when you can get the same results for $1000 less by letting TEA CNC-port your heads? The AFRs have their applications, but you're nowhere close. You can reach your goals with the 5.3 heads you have, and nitrous, and a Jacobs Nitrous Mastermind. And a used LS6 intake. And headers. You go with a 200 horse nitrous kit, then set the jacobs to give you 50% of that down at 3000 rpm, and progressively increase to 100% at 6000 rpm. If you want to spend more, start with forged pistons, and file-fit plasma-moly rings gapped for nitrous. Want to spend more, and exceed 700 ft-lbs at the rears? get a pair of T4S04 turbos. They're perfect for a 5.3L, even better than a single T76.
Don't forget about the problem you'll have with the LM7 accessory drive, IIRC the LM7's idler pulley will be right in the way of the throttle body when using the F-body intake. You may have to go with F-body accessories or there may some companies out there that have a idler pulley relocation kit.
