Chevy Silverado and GMC Sierra Forum banner
Status
Not open for further replies.

how to get some more power out of a 5.3

254K views 33 replies 16 participants last post by  RedSLEd  
#1 ·
I am new to this website and was wanting to see if anyone had some good suggestions of what to put on my engine to get more power out of it. I already have a k&n cold air intake, exhaust system, throttle body spacer, and Edge programmer. And I don't want to spend too much on it but I am open to any suggestions. I would like to get around 400-425 hp out of it. Can my stock transmission and rear end handle that much power? Thanks
 
#5 ·
want a bolt on for lots of hp? One word: supercharger.

As for your driveline, no your tranny won't handle that kind of power. Right out of the box GM trucks are equipped with a torque management system that only allows so much power to be put through the tranny at one time just for that reason. It certainly helps with longevity, but it's kind of lame for those of us who love to feel all the horsepower that 5.3 has (guys who really build up their trucks will always get this disabled). The stock tranny is really pretty weak, and only designed to handle the power that a stock 5.3 puts out. Your rear end will be able to handle a it ok I would imagine, but I don't know enough about these specific diffs to say for sure. I'd probably bet that 400+ hp would make it whine pretty good though.

I've posted this before, but it's a good read, and a quick way to get well over 400 hp out of your 5.3l
http://www.carcraft.com/techarticles/cc ... ewall.html
 
Save
#6 ·
That's what I was afraid of... so I will just forget about the 400 hp with bolt on parts. But what can I get? And I still don't want to put a ton of money into this truck. I might be asking a question that there isn't a good answer to. Is what I've done to it about all I can do with bolt on's with out killing my tranny? And would it be a good idea to have the torque management system disabled or is it more risk than its worth? I'm sorry I know I'm asking a lot of questions.
 
#10 ·
The only way you are going to get there is to do some work to the motor...

You have to build up the motor to boost it. Or if you want to go the normally aspirated route, you have to quite a bit of work to the motor just to get it to put out those numbers on its own.

I'm assuming you have the 4l60E. That tranny is going to need some work to it too just to get it to hold up.

Piddly things like a cold air intake, or bigger throttle body will not get you there.

And since you don't want to kill your fuel mileage, you aren't going to be happy either way, since making these modifications to get you there will require more air into the engine to get there. More air will require more fuel. Simple equation there results in lower fuel mileage.
 
#13 ·
1500VHO

Thanks for the link that does help me. The only thing is that now I realize that my tranny can't handle it I might as well forget doing any major mods to it. So just asking would I get any more power if even enough to worry with out of changing out my CATS and maybe some shorty headers or is that more trouble than help?

and a side point I don't really like my edge programmer the shift points are so firm it is jerky most of the time and the speed correction for my tires throws my ABS and Break lights off on the dash. So is that normal for all programmers, just edge, or my truck??? I might need to start a new thread somewhere for this I'm not sure.

Thanks for anything on both these questions.
 
#14 ·
Yeah they are very true, while cold air does make a bit of a difference it maybe be only 10hp
If you don't have headers I would get some shortys and if the transmission is a 6 speed 400hp isn't much stress on it, 4l60e... Don't even try it and expect longevity
But the guy talking about gears is correct, you probably have 3.42s, if not?, put 3.90 or 4.10 gears in it. Enormous difference.
Example, 3.06x3.42= 10.46x360(pounds of torque)
=3676 lb-ft of torque to the wheels
3.06 is first gear ratio of a 4l60 and 3.42 is the final drive gear
360 is just an estimate of the torque your making with the add ins given its the newer 5.3 making 335 torque
Change to a 3.90. 3.06x3.90=11.93x(360)
=4296lb-ft
That is 600 more pounds of torque to the wheels, which is a bigg amount, you will definitely notice that
Hope I could help
 
#15 ·
sierra07 said:
1500VHO

Thanks for the link that does help me. The only thing is that now I realize that my tranny can't handle it I might as well forget doing any major mods to it. So just asking would I get any more power if even enough to worry with out of changing out my CATS and maybe some shorty headers or is that more trouble than help?

and a side point I don't really like my edge programmer the shift points are so firm it is jerky most of the time and the speed correction for my tires throws my ABS and Break lights off on the dash. So is that normal for all programmers, just edge, or my truck??? I might need to start a new thread somewhere for this I'm not sure.

Thanks for anything on both these questions.
Hi,

Question 1: Long tube headers have proven to be the best answer for more HP and a broader torque band...
Shorty headers, in most cases and reports from web sites do not offer great results...
CATs - There are high flow cats out there, but long tube headers along with a good cat back system will gain more power for you...

Here's a link that compares stock vs shorty headers vs long tube headers: Fourwheeler

Question 2: If your want to more "real" power and possibly better gas mileage, get a Diablo InTune or Trinity. Then get in touch with Lew... He is here on this site as 06MonteSS... Also here's a link to his web site: Diablew He can get you a "custom tune" based on your particular engine combo. Several folks here on SS.com have used him, and swear by him... He made a BIG difference with my 6.0L engine in my truck. Shifts are firm at RPM, but not harsh... Normal shifts under day to day driving. I also got better throttle response, and gas mileage by 1.5-2.0mpg.

I hope this helped, :D
 
#16 ·
There's always a lot of confusion on this topic of how to get more power, so I would just like to make a few statements that should get everybody pointed on the right path...hopefully somebody will chime in if I misspeak or miss something altogether, but here goes.

Number one thing to know is that these truck come detuned right off the lot. The 5.3 is rated for 315-325 hp, but you aren't going to see all of that get used. The absolute best bang for your buck, and best thing you can do to let your truck use the power it has is to get it custom tuned (as was mentioned in the previous post) and that alone will make it feel like you are getting WAY more power than you actually are. The tune will allow your motor to run as hard as it is built to.

Next: if you just want more pickup off the line, you need torque. You can accomplish this by changing your gears, changing your tires, swapping trannies, or going all the way and getting a cam/crank setup that is built for low end power. Just don't be suprised when your top end suffers dearly for this. EG: I had an old farm truck that never went over 50km/h, so I threw in a 4.56 rear end. It could pull a house off its foundation, but i'll be damned if it could get up to highway speed.

If you want more top speed you need more horsepower, or if you already have enough horsepower you need to change the driveline to get that power delivered at a higher speed (note that your acceleration will drop steeply) eg: I had an old cutlass with 2.56 gears in the rear end. it did 150 km/h in second gear...but took a solid two minutes to get up there. As far as horsepower goes you basically need to dump in more fuel. (note that your fuel mileage will generally suffer). Of course you also need a certain amount of air to be able to burn that fuel properly in order to extract as much power as possible (this will result in higher efficiency, and possible increased mileage). Putting in bigger injectors is only useful if you have a fuel system that can provide adequate flow. Using that much fuel is only great if you have pistons,rings etc. that can take all the extra heat generated. Pumping in that much fuel is only useful if your air flow can keep up (that includes flow in AND out). Safe bet is that horsepower mods = economy loss.

This all being said, if you want your truck to go faster, push the pedal down farther. If the pedal is on the floor and it still isn't enough, then you need to get more air in and out. This is the only circumstance when a cold air intake is really worthwhile. At anything less than WOT a cold air intake is essentially useless. It will make a nice sound, and possibly get you a little better response, but the actual power gain is nearly negligible. You can get to the point where you are porting heads and putting in bigger valves, and if you are then you're building yourself a pretty serious machine.

Next stop (and probably the most important one IMHO) is your exhaust. The first and foremost thing I need to say here is that straight piping your exhaust is useless unless you have an EXTREMELY powerful engine with a turbo or supercharger, and are running it balls to the walls at all times (see: racing). By removing the backpressure that an exhaust system provides, you are GREATLY reducing the efficiency of the motor at lower rpms, and needlessly burning fuel without any real gains. Most people don't really understand the true purpose of an exhaust system, and assume it is merely to redirect toxic fumes away from the passengers and drop the decibel level of the engine. While it does do both those things, it also has a much greater purpose. Somebody who wants incredible top speeds will have a much different exhaust setup than somebody who wants a ton of power at their bottom end. Changing out your cats is beneficial if you have plugged cats. Otherwise, new trucks have fairly efficient cats from the get go, and any benefit from deleting or swapping them is very minimal and probably one of the last things I would recommend changing out. If you go and buy yourself a cherry bomb and slap it in, and cut off all the pipe behind it, be ready for terrible fuel mileage and an actual drop in power. MAKING YOUR EXHAUST BIGGER DOES NOT ALWAYS EQUAL MORE POWER. Your exhaust needs to be matched up with your intake so that a) the motor is not working too hard to force out the exhaust and b) has enough velocity to maintain a proper flow in and out of the cylinders. Bigger exhaust = lower velocity. smaller exhaust = higher velocity. A high end muffler has properties that will allow the amount of backpressure to change with the speed of the motor and let it breathe properly. A cheap muffler, simply said, will not do this. the piping after the muffler is also important in that the muffler was designed to have piping come after it, and will not work as well as it can if it doesn't have this. If you are going to spend some bucks anywhere, I highly recommend spending it on your exhaust. A performance exhaust shop knows all this and more, and can help you design the perfect system for your purpose. Be aware, though that you need to plan the exhaust to match up with other mods that you are doing in order for it to work harmoniously and as efficiently as possible. Long tube headers are great, they help a ton with air flow and getting some extra power. Shortys sound nice and that's about it.

So, my final piece of advice is to save up your bucks and get all your mods done at once. This way you can buy everything so it matches up with the rest of the package, and you won't end up having to continually change out different things to get it all working the way you want. Get a tune done AFTER you've done everything else, and that way your computer will know how to use all the goodies you've installed.

That's my rant for now, hopefully it all makes sense and is correct. (I'm working nights right now, so hopefully my lack of sleep hasn't made me delusional)
 
Save
#17 ·
Hi Campfire,

No delusions there... In fact, I think it's spot on... What you really want on the street, and in a truck is Torque... Torque makes things move... As you so eloquently stated. I love the tractor example... :lol:

This is why I pointed to Long tube headers... They "seem" to broaden the power curve (torque) and add a little HP above 5,000rpm... But for most trucks, we don't run them at 5,000 - 5,700rpm all the time. I bet very infrequently... The down side of Headers of any kind, is longevity, heat in engine compartment, and maintenance keeping the bolts tight over time... However, I do like the way they sound and look. But in Michigan, with winter and salty roads, they would not last long!

My stock truck, 2005 Silverado VHO, with a Lew tune, Corsa dB cat back exhaust (Great muffler BTW) and Volant CAI, performs very strongly and runs past 140mph if I'm so incline to make it do so... Off the line, it will press your spine into the seat.. That's all I want... Is it the fastest truck or vehicle in my area, of course not! Is it the fastest vehicle I've ever owned, No. That prize goes to my 1969 Camaro with a 427cid and 4.10 posi. But my truck is sure more pleasurable to drive, gets better gas mileage, AND it can haul and tow stuff... That's why I love my truck!!!

So as a last word - a "Pro" tune (Lew) and Diablo programmer is the best bang for the buck... IMHO.

Take care and good read! :D
 
#19 ·
Hi Emily,

Not what the manufacturers claim.. If that were the case, my little motor would be over 400HP... The CAI in conjunction with a good Cat back exhaust system lets the motor breathe... Then Lew or a "Pro" type tuner can extract everything that the motor is capable of putting out. You'll "FeeL" a difference... How much, total?? I would like to think at least 20HP and 25f/lbs of torque. But without going to a dyno, or reading that a magazine has made ONLY these exact mods, it's hard to say.

My 6.0L LQ9 was rated by GM at 345HP/380ft/lbs Torque. Every magazine I've read states that the numbers are really 356HP/397ft/lbs Torque. So right off the bat GM was conservative. I truly believe that the engine is how putting out somewhere between 370-375HP and 415-420ft/lbs of torque. Only a dyno would be really able to detect these numbers...

But it's sure fun "bench racing" and telling stories... However, at my age, I tell the truth, rather than stretching it like I did in the ol' days...

I hope this helped, :D
 
#22 ·
Emily,
Your truck new IAW to GM put out 305 HP stock.
With the tune, CAI and flowmaster you are well over the 330 -- IMO
Tom
I thought that my truck was rated at 285? Then again, maybe it's GM being conservative again. By the way, what does IAW mean?
 
Save
#24 ·
Camfire and 1500vho thanks for all the info y'all told me all I needed to know and then some. I will look into the programmer for sure and maybe the headers if they are not a ton of problems to get installed. There really isn't a good shop around here I would trust with doing the long tube headers. And while Im here do the headers sound any different than stock?
 
#25 ·
DarkGothic said:
How much horsepower can you expect to tack on with popular mods such as CAI, exhaust, and handheld tuners? Just curious.
Well that's sort of a hard question to get a straight answer for. The power gains that are stated by the manufacturers are, as you would expect, the very top gains made at the very peak of horsepower production of a given motor. That is to say, that if you throw a CAI on a Honda 1.8l, it's going to give you significantly less power than if you put it on a Chevy 8.1l. The power you'll see out of any "intake" mods is going to be at high rpm and WOT. when you look at the curves they supply you'll see that down at the bottom of the power band there is little to no difference between stock and with the intake installed.

Tuners are similar in that different engines will get different results. A bone stock 1.8l with a tune is going to maybe get 15 hp at best if the tune is really well done and custom for that motor. An 8.1l with full racing exhaust, supercharger, ported heads, large bore injectors and forged bottom end could get 100hp out of a tune. It's all a matter of making what you have work better together. The handheld tuners are nice if they have the option to customize all the parameters yourself, or get somebody like Lew to make up a custom program. The ones that just have an up and down button for more or less horsepower kind of scare me haha, who knows what they're actually doing.

Exhaust also can vary greatly. Depending on how you set it up, exhaust can be made to provide for more power at the low end or top end depending on what you want, and two different styles of muffler with the same pipes hooked up will provide very different results. To use the same example again, that little Honda might get 10 hp by throwing a big fart-bomb exhaust on the back end (though it will probably also burn the valves out in a week) While the Chevy could get up to 80 hp with a full kit installed (but once again, that depends a great deal on what is hooked up to the intake side of the motor as well). For a cat-back system, if you're willing to spend the money to buy a high quality kit, it's not unreasonable to expect 30hp out of a v8.

In the end you would probably be suprised at what a 10hp difference feels like. It's quite substantial. Many mods that are commonly done don't actually make for much extra power, but they just let the motor work more easily to use up the power it was built with.

sierra07 said:
Camfire and 1500vho thanks for all the info y'all told me all I needed to know and then some. I will look into the programmer for sure and maybe the headers if they are not a ton of problems to get installed. There really isn't a good shop around here I would trust with doing the long tube headers. And while Im here do the headers sound any different than stock?
The headers aren't terribly bad to install yourself, and that can cut down on the costs. Not to mention after installing them yourself you'll know exactly how to get to all the bolts you'll need to tighten up every so often (headers tend to shake themselves loose over time). The only time you may want a shop involved is if you're having the whole system welded. I personally have no problem with using donut gaskets and clamps because they can be taken off and put back on easily. You won't have issues with leaking if you take your time and do it properly. And yes, hell yes those headers sound different than stock! They will give you a really nice rumble when you lay into it.
 
Save
Status
Not open for further replies.
You have insufficient privileges to reply here.