INTERNAL ENGINE MODIFICATIONS Valvetrain |Heads | Strokers | Design | Assembly

Looking for a few suggestions on building an LM7

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Old 05-06-2013, 09:10 PM
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Originally Posted by zero2sixT
Ah, its clear to me now. From your first post, I thought you were going to run the gen IV.

Sorry, yes you are right. You should mill the 243s.

And yeah that is how I would do it. Manipulate the rear end gear ratio with tire height. Good luck man
Thanks everyone for all the help, appreciate it. I did lots of reading, but wanted to make sure I wasn't heading in the wrong direction.
Old 06-22-2013, 01:32 PM
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Just an update. Took it to the track last night to get a baseline before I start into the engine as I plan to do this in stages. Truck ran as follows:

1996 rcsb stepside with an LM7 from an 03. Stock engine tune, shorties, no cats, true duals, shift points upped 200rpm, torque management 70% off, TCI breakaway convertor, Stock 3.42 gearing with 26.8" tall tire, true trac posi.

Truck ran a best of 14.621 @ 94.91mph.

Ordering cam/springs/pushrods Monday. Hopefully tuned and back to the track in a couple weeks to get new numbers.
Old 06-25-2013, 06:10 PM
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Good Luck with the build
Old 08-09-2013, 10:25 PM
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Got back to the track. Added a comp XR275hr cam, pushrods and springs. Got the VE and Maf tuned but have yet to touch the spark tables (show no knock retard) and grabbed a pair of MT et streets. Ran a 14.13 @ 97.56mph. 60ft times dropped to 2.0829 from 2.3709, I actually expectd more time to be made up there. My injectors are at 96% so I'm pretty much maxed out there, until I upgrade. Still have the 243 heads and tbss style intake, but I just bought an lq4 and I'm thinking that that motor may benefit from them more. Not sure what to do next as I don't want to start spending mega $'s for minimal gains.
Old 09-08-2013, 12:26 PM
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Back to the track. Added 4* timing, still no signs of any KR. Ran 13.99 @ 98.x mph. Might be able to squeeze a couple more 10ths, but I think this is close to the best this engine's going to run. That's bone stock, shorties and a cam and a converter that's actually stalling 2300ish according to my logs. It's pretty fun on the street, but I want more so I'm going to build the 6 over the winter. Thanks for the help guys, was a fun little test.
Old 09-08-2013, 03:16 PM
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That's not bad at all. I bet there is a little bit left in it with a better tune and maybe some more fuel. If your going to swap a 6L in I wouldn't spend too much time on it though.

Its kinda cool to see a 5.3 make it into the 13's with only a cam and converter essentially.........
Old 09-08-2013, 08:24 PM
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It would probably drop a half second and still be streetable with a true 3000-3200 stall. This truck is a riot on the street and I'd guess it still gets 23-25 mpg, but I want 12s and I'm not going to stop till it's there.
Old 09-14-2013, 05:32 PM
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Make sure you post a thread when you do the 6.0L build. This 5.3L thread was interesting, especially with the track numbers.
Old 09-15-2013, 09:21 PM
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Will do for sure. I'm waiting on cometic head gaskets to show up, then I'm going to start building the 6.0l. I want the truck to run in the 12's with the 6. I need to drop a sec, I figure that the 6 with 243 heads, nnbs intake and throttle body, .40 Cometics, long tubes, the same xr275hr cam has to be good for that, all though it is going to run through an 80e with a 2800 stall now. I hate it when big hp numbers get posted but no et's. I like to base my progress on how much faster it makes the truck, nobody's racing on a dyno.
Old 12-20-2014, 11:04 PM
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Quick update, I put the 6.0l together over the last winter, but never posted anything because unlike the 5.3, I did everything all at once. The truck currently is setup like this:

Lq4, stock 243 heads, .40 cometics head gaskets, tbss intake with 87mm throttle body, 40lb injectors, the same Comp xr275hr cam, shoenfeld long tube headers, dual 3" exhaust with a single magnaflow xflow muffler, 4l80e with a transgo hd2 shift kit, 2800 stall, 4.10 gears and the same 26" et streets.

Truck ran a best of 13.09 @ 107.5mph. After running that I got home and realized that my spark tables were somehow switched to stock and I was running about 10* less then I should have been, and never got a chance to get back to the track. I'm sure it's got 12's in it in the spring. It's crazy fun right now, driven right it will bring close to 20mpg. Just thought I'd share.


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