LM7 upgrades for rock crawler??

New to the forum and LS engines. I have tried to read up but there is just so much that only makes sense after you know it, so please go easy on me if I'm asking questions that should seem obvious.

I'm helping my buddy with a rock crawler build, basically all custom frame and suspension with an old school Jeep body and grill, and after reading up we decided that LSX powertrain was the way to go. Wanting to stay in a budget for engine he jumped at the opportunity when he was able to get a '99 LM7 drop for $280 (no harness or computer). We will be buying a used factory harness and PCM and doing the wiring mods ourself, getting the PCM reprogrammed.

The question is this: Without spending a lot of cash, what are worthwhile upgrades to this engine? We'd consider dropping in a factory cam from a LS? motor, but don't know it's be worth the $50-$100 in parts. What would be the best (stock) cam that would be a direct bolt-in (springs and pushrods matched, of course)? Also, what throttle body would serve best? Would an injector upgrade be in order? While the engine is apart for inspection, would we benefit from swapping in 4.8 (flat) pistons? Is there anything to gain by "gasket matching" heads?

Basically I'm looking for the "formula" to get more out of this on the cheap, with a focus on torque as much as HP. Though HP is good for a large hill climb, it's the torque that pushes you over the rocks.

For now, we'd considered the following:
air intake (before TB) will just be a short large diameter tube and a K&N filter... no restrictions before TB.
The plan for the exhaust is to cut just behind FWD O2 sensors on stock exhaust and run same diameter, unrestricted, from there back.
All smog will be deleted.
Fan will be electric.
AC compressor will be retained, but not engaged (except as occasional air compressor for tires, etc).
Manual (SM465) trans
F-body oil pan (for rock clearance)

With this setup, based on what I've read, we expect to see around 315-ish HP. Is that about right? Is there a cam combo that, along with Camaro TB and performance PCM tune, will get us up to 400+ HP without sacrificing low end torque?

Also, does anyone here do/recommend performance tunes? We're considering garretttuning.com as the price seems good and it seems like it'd include whatever we need. Is there a better solution recommended?



Thanks for any advice and assistance.

For your custom tuning needs look no further than Nelson performance. $300 and includes free retunes.
Hp/tq to the wheels of a stock 5.3 expect 200-225. With the basic mods you listed maybe 250-275.
400 to the wheels will require heads and cam or forced induction.
Best budget cam is prolly LS6 cam with hardened pushrods and yellow springs. $250-300ish and 40hp
or get a full out thunder racing cam kit for $600 and 75hp
Swapping to 4.8 pistons will be a great upgrade especially for downlow power.
78mm tb's are all the same, but some gains from a good p&P job.

Ls6 can doesn't have the bottom end grunt you need.

If you have the heads off swap the flat top pistons in and get the heads milled.

Best bang for your buck for that type of performance IMO would be a maggie, and the other supporting mods like tuning and fuel system.

Quote:

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Originally Posted by jansen

Ls6 can doesn't have the bottom end grunt you need.

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What? That is the baby cam of baby cams. Dyno sheet of a ls6 cam in a 5.7 with boltons. Note the torque curve.
http://ls1tech.com/forums/dynamomete...-firehawk.html

Quote:

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Originally Posted by kerrige

What? That is the baby cam of baby cams. Dyno sheet of a ls6 cam in a 5.7 with boltons. Note the torque curve.
http://ls1tech.com/forums/dynamomete...-firehawk.html

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He also added more parts than just the cam....just saying I would be willing to be that the majority of the gains seen there are NOT from the LS6 cam.
:twocents:

Everyone always complains about their lack of bottom end with this can in a truck. Also the engine in the link was a 5.7 and in a car, not a very good comparison for a rock crawler.

and remember his budget, and for rock crawling he wants more torque. I would just drop in the lm7, tune, make the intake, and gears (4.56 or lower). im sure that chassis will be light enough!

Quote:

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Originally Posted by bangbangskeetskeet

He also added more parts than just the cam....just saying I would be willing to be that the majority of the gains seen there are NOT from the LS6 cam.
:twocents:

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Quote:

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Originally Posted by jansen

Everyone always complains about their lack of bottom end with this can in a truck. Also the engine in the link was a 5.7 and in a car, not a very good comparison for a rock crawler.

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We are talking torque curves here. The dyno doesn't lie when it comes to the actual curve and those boltons are very basic ones the OP suggested he would be using. The 5.7 is only very slightly different from the LM7 power wise. Also car vs truck doesn't change a torque curve on a dyno. The LS6 cam shows significant gains for the price including down low. You can't expect big gains down low no matter what the cam. He asked what stock cam would work and still receive a bump in performance. It will still be better than stock which is what he asked.

Quote:

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Originally Posted by kerrige

Also car vs truck doesn't change a torque curve on a dyno.

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. It will if its got a car intake on it.

Quote:

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Originally Posted by kerrige

We are talking torque curves here. The dyno doesn't lie when it comes to the actual curve and those boltons are very basic ones the OP suggested he would be using. The 5.7 is only very slightly different from the LM7 power wise. Also car vs truck doesn't change a torque curve on a dyno. The LS6 cam shows significant gains for the price including down low. You can't expect big gains down low no matter what the cam. He asked what stock cam would work and still receive a bump in performance. It will still be better than stock which is what he asked.

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Whats the compression of a stock LS1...10.5:1. The compression of a stock LM7...9.1:1.
It makes a difference. Thats why when you add more parts to the LS1 you will net larger gains across the board period. Sure adding the flat tops to the LM7 will help with the compression, but you still lack the displacement.

And yeah I know that its a budget build so why not save the money needed to do the cam swap and spend it on something more usefull like saving it to buy a maggie or gears.

Want torque? Add compression. Flat top pistons, mill the heads. Look into EPS "Truck Torque" cams. Use the truck intake, stock tb. Dyno tune it to get the timing and fuel curve absolutely perfect. Allen at NP is a good tuner, but mail order just cannot account for all the variables. Find a decent local guy, or buy HPTUNERS and email logs and tunes back and forth.

You mean a Magnuson Superchargers? Isn't that $5k? Not the budget we were looking for. The HP/TQ numbers I mentioned were flywheel, I guess. We cannot begin to guess the losses by the time it goes through a manual trans, 2 transfer cases, and extremely low axle gearing. It'd get beat by every Kia on the strip, but then crawl over it in the parking lot.

Though it's ghetto-fabbed, the exhaust will be practically wide open, the largest restriction being where the manifold flange is. The intake is wide open too. Can I not expect 300 HP/330 ft/lbs?

His goal is to go through the bearings and rings, so since the heads are off I figured why not do what we can on the cheap... remember, the engine and harness and PCM will be less than $450. There's a local junkyard that sells by the part generic, no a busted up 4 cyl and a LS7 are priced the same, though you'd never get you hands on something like that. So going back for a oil pan from this car and pistons from that truck is cheap, maybe cheaper than he could get back for his pulls on eBay or something, and can maybe find a LS1 cam or LS6 or something pretty cheap. A very mild gasket match and blend of heads is all we're comfortable with doing in the garage here.

So we wanna know if we are getting a cheap cam from eBay or a forum, what's a good suggestion? I can get a LS1 with springs for cheap, and was wondering how that and LR4 pistons and a good tune will do?

Again cost-minded, anyone have any experience with garretttuning.com? I'm sure Nelson is good if you recommend them that solidly, but would we do bad at the other route at half the price? How likely are we to need a retune in our senario?

I really appreciate all the input. I know there will be different perspectives, but really am focused on the budget. Thanks, and keep it coming.

An ls6 cam is the only stocker you could justify vs. time and expense

With time and know how swapping to 4.8 pistons will be some serious bang for your buck. As for retunes you will most likely want to make changes later right? Then yes you will need retunes later, most likely several times. If you really are sure you won't ever want a retune I believe NP offers something called a hot rod tune. Cheaper, but no free retunes.

Yeah a Maggie is more expensive but will net you 2-3x more than all the stuff you're going to do now. Your truck your decision.

Seeing how you're not going to spend that kind of money most likely why not take the money for the cam swap and get some long tube headers to free up the exhaust?