5.3 ls swap low end power

[mcarmack]

LYNNFISHER.LSSWAP-2.hpt
I put a 5.3L in a 1984 k20 truck. came out of a 99 or 2000 truck. I have performed a basic tune on it, turned off all EVAP, EGR, Sensor 2's, speed limiters, COT, theft deterrent, and leaned out the power enrichment. I am far from a veteran at hp tuners software. I sold this LS conversion to the customer to help with horse power over the 350 that he did have. it helped a lot but still need a little more low end power. truck has the original 4 speed manual transmission in it. what can I do with the programming to help with low end power? and also truck is kind of doggy on the high end also , no guts at all in 4th gear, what could I do to help with that?
any help is much appreciated, im doing my best to learn. I uploaded my latest tune for it

[matty b]

That motor is good for 290hp BRAND NEW. Was the motor rebuilt? What kind of mileage is on it? Any bolt ons?

The heads on those motors suck, the cam is less than tiny and the timing curve leaves a ton to be desired.

[mcarmack]

motor was rebuilt, its very fresh. only bolt ons are headers and cold air. everything else factory, stock cam .

[5FDP]

You might just be at that limit.

The heads aren't terrible, the 706/862 early heads are known for cracking/leaking coolant though.

You could do a VE and MAF tune on it because you changed the intake and went to headers, that might help pick up a few horsepower. But you'll have to change the cam or change the rear end gears to get more out of it.

And if you did cam the motor, you'll need/want bigger injectors. I know the 99's had the smallest injectors of the bunch and barely support bolt on level power.

[matty b]

I wouldn't expect much more than 320 hp with that and a perfect tune. More or less a tune just isn't gonna do much for you. Now if you put in a cam, that's a different story, you'll wake that summbitch right up.

A big truck with big tires and alright gears just isn't gonna give the oomph most guys are looking for. I'd look at an XR265HR or XR271HR are great cams that wake up otherwise stock 5.3's. You'll need springs and pushrods though.

Theres always the tried and true 02-04 LS6 cam or LS2 cam if you wanna go through the trouble of moving the cam sensor to the timing cover. Those cams are great at making more power without destroying your bottom end. Those 4 cams are what I stick to on trucks that will be daily driven and they aren't being built for drag racing.

[PeteZ]

im no pro at this but you may can advance timing at higher kpa values and rpm and maybe smoothout the ve table.

[matty b]

im no pro at this but you may can advance timing at higher kpa values and rpm and maybe smoothout the ve table.

It really doesn't help that much. 5.3's need a cam to make any power. A car I set up with an L33 which has LS6 heads, 4.8 flat tops and a bigger cam makes 320 stock bhp. With long tubes and a custom CAI I made just around 300 wheel with a pretty aggressive tune for me.

With an XR281HR on that motor and port work, I was able to bump that to 345 wheel. Thats for a lightweight Chevy II and not a big truck. I would not do that setup for anything over 3500# that spent its life below 3000 rpm.