Topic: Best Bolt On's for performance?

[worm25]

Just wondering where to start to get the best bang for my buck with some performance mods.  The only performance mods I've made to date is a K&N cold air induction system and magnaflow catback exhuast.  I see things like superchips, TB spacers, ect. but I'm really not sure what route to take.  Someone let me know how I can feed a little more juice to the ride..........  maybe some combos you are running would be nice as well.

Thanks,

Jamie

[Main One]

Programmers (or a custom tune) are good, especially as you add bolt-ons.

I wouldn't bother with a TB spacer.

Headers are good.

Underdrive pulleys are good.

A bigger cam is good, and will probably give the most noticeable improvement.

A higher stall torque converter will give you more punch off the line.

Some may say iridium spark plugs and low resistance plug wires - I'm not sure how much they are helping me.

[MyBigToy]

My first choice, after the basic mods you've done, would be a higher stall torque converter. It will give you the biggest measurable performance increase. You'll need a programmer to tweak the shifting; I'd recommend the Diablosport Predator or you could take the truck in and have a custom tune done.

If you plan to stay naturally aspirated I'd probably go with a 3000 stall; if you might add forced induction at a later date I'd probably go with a 2600, depending on the type of FI you choose. I can give you some torque converter brand suggestions if you'd like. I see you've got an 08 so If you have the 6-speed auto (I don't remember when the 6-speed came about) the stall choice may be different than for the 4-speed auto, which is what I've got.

Beyond that, you could do headers and a cam. Forced induction will give you a big boost but it's also big $ and once you add it you have to start beefing up other things like the tranny. We like spending other people's money almost as much as we like spending our own! 

Whatever you do, keep your ultimate goal in mind and make sure you pick items that will complement each other and will work with your ultimate combination. Do your research before you pick anything so that you don't regret it because you made the wrong choice.

BTW: my mods are in my signature; I've spent way too much money on my "baby"!  Good luck and have fun modding.

[Ski Edition]

How indepth is a cam change and what other parts would need to or should be changed during the process?  What would a cam change do for a basic stock AV (mine)?

[MyBigToy]

How indepth is a cam change and what other parts would need to or should be changed during the process?  What would a cam change do for a basic stock AV (mine)?

Pretty much the whole front of the engine and the radiator have to come off, as well as the valve covers and fuel rails. You don't technically have to take some things off but it makes it easier to do the install. Aside from the cam you'll need new compatible springs and most times it's recommended to go with hardened pushrods because replacement cams typically have faster lobe ramp rates and higher lift. You may have to replace the spring seats and retainers also but most times it's not absolutely necessary. Depending on how many miles you have on the truck you may want to consider replacing the timing chain and gears while you are in there. You could also consider changing out the water pump if you have a lot of miles on the truck. You'll also need assorted replacement seals and gaskets for everything you remove from the engine.

What would a cam change do? It typically gives you more horsepower and torque over a wider rpm range than a stock cam. Proper cam choice is critical for how you use your truck; since you tow you don't want to go with a cam that has mostly high rpm power. You could reasonably expect to see an increase of anywhere between 20-50 horsepower depending on the cam. You could go with a slightly higher-stall converter to allow you to go with a slightly higher rpm cam but again, a high rpm converter is not ideal for towing. You could get away with a 2600 stall like I've got but I personally wouldn't go any higher than that; I tow occasionally and the main place I noticed the difference was when backing the trailer up. You have less-precise control of the movement of the truck/trailer combo. I liken it to a rubber band effect - you step on the gas, the rubber band winds up and reaches enough tension to start the truck moving, then it starts moving. By then you've let off the gas and start the cycle all over again.

That should give you a pretty good idea of how involved the job is; you could do the change in a hard weekend with some help that's done it before. I see guys posting on PT.net that they can do a change in 4 hours but that would be someone who does it all the time and taking shortcuts that I personally wouldn't want to risk taking.

[Main One]

I did mine having never done it before but with a real good write-up that someone did when changing the cam on an LS1 powered Trans Am.  It took about all of a 3-day weekend.  (I did go to church Sunday morning.)  Also helped KY_Bob put his in after doing mine.  It took us a 2-day weekend, but we had a couple of issues: 1-his cam came with the alignment dowel missing which we had to track down a suitable replacement, and 2-he dropped a cam gear bolt into his oil pan which took about an hour of fishing with a magnet to pull out.

Pretty much what you need to do:

Pull the radiator - not too bad of a job but need to deal with the fluid.

Remove the valve covers - not too bad.

Remove the rockers - not too bad.

Remove the pushrods - at this point a piece of cake.

Remove the front crank pulley.  This thing is really torqued down.  I locked the crank via vice grips in the bell housing inspection opening on the flexplate and needed a breaker bar and iron pipe extension to break loose.

Remove the water pump - not too bad.

Remove the front engine cover - not too bad.

Spin the cam to get the lifters up.  Very easy.

You can assume the lifters will stay up before you get the new cam installed to save you from having to pull a head(s) or do like I did and use 16 magnets to hold them up.  There is also a couple of openings in the front of the block that you can remove plugs from and insert a rod that will hold up the lfiters.

Remove the cam gear - not bad but stick a rag into the gap exposing the oil pan so you don't do a KY_Bob and drop a bolt into the pan.

Remove the cam.

I also replaced the pushrods (about $150) and upgraded the valve springs with dual springs.  A cheap valve spring compressor works great with single springs, but was a real PITA with the duals, but after about 6 hours I managed to get them all installed.  I think I also changed valve seals, but it has been a long time.  I did not change valve retainers - titaniums are available for higher RPM applications.  I also purchased about a dozen spare valve locks as these are very small and easy to drop and loose.  Other than dealing with the dual springs, which would have been MUCH easier if I had spent another $200 for a better spring compressor, this wasn't too bad.

Now you just put things back together.  I reused the water pump gaskets but replaced the front main seal that I took off of the front cover.  The pulley crank nut is a 1-time use item that you will need to replace.  I spent the extra money on an ARP nut that is reuseable vice a GM one, mainly since the place I bought it from was out of stock of the GM nut.

Then you reinstall the things that you took off.  Oil the cam up well before reinstalling.  With roller lifters, you only need to use regular engine oil on the cam, but assembly lube works ok too.

After the install, unless you went with a cam with such a little amount of change that it would hardly be worth the trouble of installing it, you will need a custom tune, primarily to bump your idle speed and corresponding airflow.  Stock, my idle speed was 550.  With my cam, I need an idle speed of at least 700 rpm in order to keep it from setting misfire codes due to the rougher idle at lower idle speeds.  I also changed the settings of how much the airflow was bumped with my foot off the the pedal at higher rpms due to the truck not wanting to slow down with my foot off the gas on the freeway.  (Stock it was adding some airflow - I've got it set now to just give the engine the idle airflow at all engine speeds when I lift my foot off the gas.)  You may also want to tweak some your tranny shift points and where the torque converter locks due to a different power range from the engine.

I went with a 216/224 degree at 0.500 inch lift intake/exhaust duration, 0.551 inch max lift with stock rocker ratio cam which is supposed to add power over stock from 1500 up to 6000+ rpm.  (Rocker lift is supposed to occur at 6600 rpm so you don't want to go above there.)  I really notice a difference above 3000 rpm.  Comparing my dyno sheets to others with basically stock trucks, I've got a pretty flat torque curve from about 3800 rpm up to about 5800.  Stock cams don't have a very flat torque curve, with max hp about 5200 rpm, my hp peaks around 5700.  More reason to hold gear a little longer at WOT and hence do a custom tune.

My cam makes enough of a difference in my naturally aspirated truck that after MBT rode in it at Bratfest last year, he decided to put one in his supercharged truck.

If I were to do it again, I would probably do a slightly bigger cam.  I don't tow though, and that should be taken into consideration.  I don't notice any loss at the low end with my cam, but I might if I was towing.  I doubt though that you do much towing running the engine below 1500 rpm.

MBT mentioned changing the cam timing gear and chain.  I did that later after doing the cam install.  To do that, you may have to pull the oil pump, if you are changing the crank sprocket to go to a double chain or a timing adjustable setup, which is what I did.  The GM tech manual instructs to drop the oil pan to do an oil pump change, although it is possible to do by only loosing the pan bolts allowing the pan to drop a bit.  It is a BIG PITA to get the oil pickup tube screws back into the pump unless you drop the pan.  Dropping the pan on 4x4's is a BIT PITA because you have to drop the front differential, etc.  The stock cam timing setups are supposed to be pretty good.  Unless you have a lot of miles, like over 200,000, I'd not try to pull the oil pump, but that's me.

[Ski Edition]

Sounds like a plan--when is your next open weekend??   

[MyBigToy]

Sounds like a plan--when is your next open weekend??   

BRATFEST! 

[Ski Edition]

Maybe a little too much to do in the park.

[Richie_Rich]

I only live a few miles from the park and have a garage full of tools.