DanielDiaz98

ok so i recently bought a truck. 1999 gmc sierra reg cab short box 2wd. love the thing. only 134k miles on the clock. comes with a 5.3 lm7. now i really want to make this thing a nice cruiser truck. and id like to reliably make around 400-450 whp on the stock bottom end. so heres the list of upgrades id like to do. not in order. 3000 stall converter. 4.10 (or 4.30) gears. full exhaust. larger throttle body, CAI, MSD ignition system. larger injectors, have the stock heads port and polished and milled to give it a little bit of a bump in compression, probably a thinner head gasket with a smaller bore while im at it, and a bigger cam obviously. and a tune. i was wondering would this set up be good for around 400 whp? how would the stock 4l60e hold up? cant find a solid answer to how much these trannies will take. some people say 350 horse others will say close to 750 horse. keep in mind this is about reliability. the transmission was recently rebuilt about 10k miles back so its in pretty good condition. since this is close to effectively doubling the stock hp and torque figures how would the rods and the piston rings hold up? i only recently switched over to chevy. before that i was a ford guy all the way so aside from knowing that these ls based engines are reliable as hell i dont know how reliable they might be under that much power. however i do love this truck and i want to make this puppy a nice bruiser. any advice on parts or different set ups would be greatly appreciated. sorry about all the questions, thank you.

Tuskyz28

That's easy at the crank. TBSS intake, long tube headers, a custom tune and cam from a vendor.

on the cam you'l have lots of choices to choose from and every one will gave they opinion. My advice is to call Pat G. He's probably the most respected cam guy there is but there is others.

JoeNova

Larger throttle body isn't really worth it unless you change the intake manifold as well.
A TBSS or gen 4 truck intake with throttle body can be done for $350-400 or so and is easily the best factory intake manifold for power and torque.

MSD ignition is a waste of money until you're making BIG power. You won't gain anything noticeable from switching to MSD, and if you have the round truck coils with heat sinks on top of them, they may very well be better than MSD coils.

Larger injectors are probably a good idea since the 99s came with some small injectors.
There are lots of factory injectors that will make 400whp.

Having the stock heads ported is one route. The only reason that's even an option on the 5.3 is because those heads have the smallest chambers. You can spend $350 and switch to 243 or 799 heads which will flow as much as your average ported 5.3 heads but they will lower compression slightly, so you can just have them milled.

Cometic makes a .040" gasket that is fairly common and will help lower compression.

Your engine will hold 400whp without batting an eye.
A 4L60e is the weak point. They have a few known issues. Usually, swapping in a 4l80e and forgetting about it forever is the way to go.


There is one problem, however. You have to figure out your budget and decide which route to go. LS engines respond so well to boost that its hard to consider anything else sometimes. A 100% bone stock engine without ever taking the valve covers off will make 400whp accidently with even the cheapest form of forced induction.


You can go the N/A route:
-Cam
-TBSS Intake
-243/799 heads
-Cometic head gaskets
-Headers
-Tune

This will get you very close to 400whp. Keep in mind that is close to 500 HP at the crank, and street manners in a heavy truck is going to suffer. The cam will likely make part throttle and low RPM torque suffer.

OR:

Don't touch the engine, do a cheap turbo setup for $1500-2000 and make 450whp. It won't sound as good without a cam, and it usually takes people out of their comfort zone, but I'll likely never go any other route on my personal vehicles.

DanielDiaz98

wow i knew ls based engines were good but i didnt know they would be so easy to make power. how about this. bigger injectors, 243 heads. cam. and a good tune. id like to keep it NA because i dont have a very large budget. pobably 1 - 1.5 grand on the engine alone. i have another question about the cam, however, would a stock oem camshaft from a later model ls engine work in this application? im talking something like an ls6 camshaft which has a pretty good amount of lift. or would you recommend i stick with the aftermarket? also this truck isnt really going to be used for hauling anything over maybe a couch or two with the occasional move in. its not a work truck and its not gonna haul anything. especially after i lower it a good 3-4 inches. its a straight line cruiser car.

JoeNova

Most people want a fortune for the larger LS6 cam.
Aftermarket will always perform better.

But, a test has been done that you might be interested in, where lots of stock cams were used in a stock 5.3.
http://www.hotrod.com/articles/ls-cam-test-comparison/
Keep an eye on the low-end torque values.

Tuskyz28

This cam looks like it will do the trick!!

DanielDiaz98

that was actually a really interesting article to read. but in the end it looks like the aftermarket camshafts beat out any of the ls camshafts. not by much but if youre paying the same for em might as well get the most. thank you that was a pretty good read. i think im starting to have a bit more of an idea of what kind of cam to get as far as lift and duration etc.

DanielDiaz98

thats actually not bad. at all. that 224 duration beats out any stock ls camshaft. definitely gonna be looking more into that one.this has actually been really helpful in understanding more about camshafts since i kind of got an idea of what specs to look for.

JoeNova

The aftermarket cams used in that comparison were less than ideal. They were all on a higher LSA which means power is shifted a little towards the top end and they have better idle/cruise. For example, the 224/232 cam is on a 115 LSA. It made 442 peak HP and lost 25 ft-lbs compared to stock at 2500 RPM.

That same cam on a 111 LSA would have likely GAINED torque at 2500 RPM and still peaked out at 430+ HP. The cam would have shown healthy gains across the entire rev range and then some. But, it will not idle as nearly as well.

I used a Howards 226/232 cam on a 115 LSA (very similar specs to the 224/232 in the article) and it was lazy down low with a stock converter. That same exact cam with a 110 LSA in my 4.8 is almost wicked. Power comes in much earlier, even with a smaller engine. Throttle response is amazing. It may make slightly less peak power than the 115 LSA, but overall power/torque under the curve will be much better.

erickk120

At 400 Hp to the crank would you consider modding the 4l60e?

gametech

iTrader: (1)

4L65 spec rebuild would be the bare minimum, and even then the design doesn't lend itself to high performance. Full throttle shifts in my old work truck with 350rwhp would slip.