99 k1500 suburban 5.7 vortec upgrades

[Superchargeme]

Hello everyone, I have a 99 k1500 suburban. I'm looking for inexpensive performance modification suggestions. I plan on doing a set of long tubes, duals with an h pipe, and a blackbear tune, but that's about all I have lined up so far. I already installed the larger stock fitment air filter as well. I was wondering what other inexpensive items I could do, and what sort of gain could be seen from them. Whenever the heads need to come off I thought about going to the thinner head gaskets, and possibly a cam. I've seen some mixed statements on whether or not 1.6 roller rockers will fit without opening the pushrod holes up. If the rockers will fit stock, I would like to go ahead and probably throw those on. I haven't owned the truck long enough to be able to tell you if there has been any interior work done on the engine(such as spider assembly or anything), but it is in a good state of repair currently with about 165k miles. The transmission was supposedly rebuilt about 30-40k miles ago. Eventually there will be an engine and 4l80 swap when this engine goes, so I don't want to put too much into this one. Just looking to improve power while still maintaining daily driver status. Looking to see what you all have to say, and what sort of power levels we're talking for each of the mod options. Thanks everyone!

 

[Erik the Awful]

A thinner head gasket will raise your compression ratio, and probably drive you to need 91 octane. I was okay with that on my truck because it's not a daily driver. If it were I wouldn't go above 9.5:1.

1.6:1 rockers will net you about 5 hp. If you pull the heads to replace the head gaskets, that would be the time to open up the pushrod holes. Personally, I'm a fan of buying a larger cam. Stamped self-aligning 1.6:1 rockers are going to cost you a hundred dollars or so. Stepping from a hot cam to a hotter cam is free, so long as you don't go past what your valvetrain can handle.

 

[Nad_Yvalhosert]

I'd love to see a set of long tubes on an IFS 4x4. Because they just dont fit...

Start with easy upgrades: free flowing air intake and cat-back

 

[Nad_Yvalhosert]

If you want headers, shorties is the way to go. However they need to have an EGR port.

 

[Superchargeme]

I didn't realize the long tubes won't fit. I was looking at a set of jba headers that said they would. How much will the shorties gain over the manifolds?

 

[letitsnow]

I didn't realize the long tubes won't fit. I was looking at a set of jba headers that said they would. How much will the shorties gain over the manifolds?

Some will tell you no gains, some will swear that the long tubes will fit, some will say that the shorties will give you big gains - and everything in between. It's about like asking which oil is the best...

When I look at a stock cast manifold and then look at say a JBA shorty, there is no way in hell that it doesn't help some.

 

[letitsnow]

As long as the tune is changed to match

 

[Erik the Awful]

On most newer vehicles, shorties don't offer much. Back in the late '80s and early '90s, manufacturers were still making garbage exhaust systems. I still remember the first time I looked under the hood of an Infiniti Q45 and said, "Holy crap! This thing comes from the factory with headers!" Still, if long tubes fit, there's no reason to go shorty.

 

[0xDEADBEEF]

My personal opinion is that if your stock manifolds aren't cracked/leaking and don't have to come off for some reason, then shorties aren't worth the effort and cost. HP gains from headers have little to do with flow, and a lot to do with exhaust scavenging. Shorties just can't get the same effect.

Shorties do shed some weight off the front of the truck, so that's one benefit. Not sure what the net is, maybe 40 lbs? Not a huge difference on a 4000+ lb vehicle. 1%.

 

[Silverado1994]

This is only my opinion but shorty's will put you where you want to be in regards to mild mods and will work with a 4WD setup. Just make sure they are a true 2.5" outlet. I'm with Erik on keeping the 1.5 ratio rockers and just going with a larger cam. Make sure you don't go above .450 lift or you'll have to machine the valve guide tips for spring retainer to valve seal clearances. I've seen where the use of beehive style valve springs along with different retainers to get around this but it still involves some money. I dunno about the thinner head gaskets and am again with Erik on skipping out on that one. Stock compression ratio for these engines is already at the 9.5:1 ratio. Any thinner than that will definitely put you in the more expensive fuel cost ranges. If you're lookin' for power, you're headed in the right direction with the valvetrain/ cam mods and exhaust. In any case it sounds like you are doing your homework which will all pay off in the end. Stock horsepower for these engines is somewhere around the 225hp range and with these heads 300hp is easily attainable and shouldn't cost you a fortune. Do keep in mind that if this engine hasn't already been rebuilt or replaced that with the mileage you've got you may have to do something there because these mods will increase cylinder pressures on an already worn engine.