400+ Hp 5.3 Natural Aspiration

clayt6499 · March 23, 2010

I have a 2008 GMC Sierra 1500 Z71 4x4 All Terrain package with the 5.3L. My goal is to try to extract 400+ hp from my truck without a supercharger or going inside the engine itself. I allready have a true dual Flowmaster super 44 custom exhaust system (which sounds great if anyone wants a sweet sounding exhaust sytem with a DEEP tone) and ordered a K&N FIPK intake kit and also just got a Diablo Sport Predator. I might add a Throttle body spacer to the mix for a little bit extra. Does anyone think i can get that kind of power with my current setup or is the a little more i need to get my goal. Right now without the Predator my truck has an estimated 350 HP with just the K&N and Exhaust. Im looking for flywheel hp right now. so if it isnt 400 to the ground ill be fine. Does anybody think It can be done? If so what else do i need to do? I want to get the most out of the motor that i can. Let me know what you think.

Z'06 · March 23, 2010

I have a 2008 GMC Sierra 1500 Z71 4x4 All Terrain package with the 5.3L. My goal is to try to extract 400+ hp from my truck without a supercharger or going inside the engine itself. I allready have a true dual Flowmaster super 44 custom exhaust system (which sounds great if anyone wants a sweet sounding exhaust sytem with a DEEP tone) and ordered a K&N FIPK intake kit and also just got a Diablo Sport Predator. I might add a Throttle body spacer to the mix for a little bit extra. Does anyone think i can get that kind of power with my current setup or is the a little more i need to get my goal. Right now without the Predator my truck has an estimated 350 HP with just the K&N and Exhaust. Im looking for flywheel hp right now. so if it isnt 400 to the ground ill be fine. Does anybody think It can be done? If so what else do i need to do? I want to get the most out of the motor that i can. Let me know what you think.

I doubt you are at 350HP right now, especially without a tune. You can't just add together the advertised HP gains. Ditch the one-size-fits-all handheld and get a PCM tune.

To get anywhere close to 400HP, you will need ported/polished heads and a good cam and be custom tuned for those mods.

Matt_ · March 23, 2010

I have a 2008 GMC Sierra 1500 Z71 4x4 All Terrain package with the 5.3L. My goal is to try to extract 400+ hp from my truck without a supercharger or going inside the engine itself. I allready have a true dual Flowmaster super 44 custom exhaust system (which sounds great if anyone wants a sweet sounding exhaust sytem with a DEEP tone) and ordered a K&N FIPK intake kit and also just got a Diablo Sport Predator. I might add a Throttle body spacer to the mix for a little bit extra. Does anyone think i can get that kind of power with my current setup or is the a little more i need to get my goal. Right now without the Predator my truck has an estimated 350 HP with just the K&N and Exhaust. Im looking for flywheel hp right now. so if it isnt 400 to the ground ill be fine. Does anybody think It can be done? If so what else do i need to do? I want to get the most out of the motor that i can. Let me know what you think.

You have set yourself up for failure... that is an unachievable goal

Your truck does not have 350 HP with an intake and exhaust, sorry for the bad news. You may get that with a really really good tune though. But unless you go forced induction or cam/heads/tune... you'll never see much more than the 350-360 HP mark, regardless of how many bolt-ons and stickers you put on.

PS: a bit of advice.... don't ever ever ever mention a "throttle body" again.

clayt6499 · March 24, 2010

I have a 2008 GMC Sierra 1500 Z71 4x4 All Terrain package with the 5.3L. My goal is to try to extract 400+ hp from my truck without a supercharger or going inside the engine itself. I allready have a true dual Flowmaster super 44 custom exhaust system (which sounds great if anyone wants a sweet sounding exhaust sytem with a DEEP tone) and ordered a K&N FIPK intake kit and also just got a Diablo Sport Predator. I might add a Throttle body spacer to the mix for a little bit extra. Does anyone think i can get that kind of power with my current setup or is the a little more i need to get my goal. Right now without the Predator my truck has an estimated 350 HP with just the K&N and Exhaust. Im looking for flywheel hp right now. so if it isnt 400 to the ground ill be fine. Does anybody think It can be done? If so what else do i need to do? I want to get the most out of the motor that i can. Let me know what you think.

You have set yourself up for failure... that is an unachievable goal

Your truck does not have 350 HP with an intake and exhaust, sorry for the bad news. You may get that with a really really good tune though. But unless you go forced induction or cam/heads/tune... you'll never see much more than the 350-360 HP mark, regardless of how many bolt-ons and stickers you put on.

PS: a bit of advice.... don't ever ever ever mention a "throttle body" again.

actually there's a few other things that Ive had done with the truck with my GM dealership.I actually am good friends with the owner of my local GM dealer. There are a few other parts already on it. And the dealer actually pulled my engine and reconfigured the PCM for my current set up. and yes it is dynoed at 353.21 flywheel hp. One thing that really helps to get these kinds of power level without forced induction is swapping the absolutely crappy Mass Air Meter that comes with the trucks and swap it for an aftermarket or performance version. they allow far greater volumes of air to pass and can read inputs faster and more efficiently than the stock unit. With any kind of air intake it really makes a difference. List of parts already consists of custom exhaust, both cats replaced with maganflow high flows and flowmaster mufflers with larger diameter piping, K&N Intake, new lightweight underdrive pulleys, Mass air meter, and the PCM slightly tuned. The transmission still has a little slop in it so im going to go back in and see if i can get the shift points tweaked some more. Im thinking of a slightly more extreme tune and a set of hooker headers (possibly wrapped for a slight bit more power). Im not sure where else to go from there without going inside the engine itself. and trying to avoid that. basically my goal is to squeeze every natural horsepower out of this engine i can. So any input would be great.

Matt_ · March 24, 2010

So before you said you had an estimated 350 HP... but what you really meant to say is that the dealer pulled the engine out of it and it has 353 HP at the flywheel?

Why did they pull the engine exactly? And seriously, if they're pulling the engine... why not toss a cam and heads on it at that point?

Your story is a bit confusing.... how about listing everything that you already have installed and everything that was done already (it did start with just an intake/exhaust, and now you have intake/exhaust/MAF/under-drive pulleys/tune...and a dyno run. Do you happen to have the printout of that run? That'd help us see where your engine is peaking and better suggest upgrades... what was the RPM?

Edit: maybe Jenna will chime in soon. She has a bunch of experience tuning those engines and will be able to give you a solid idea of what you can squeeze out of it.

Matt_ · March 24, 2010

Here's some good reading material for ya too:

Intakes: http://www.gm-trucks.com/forums/index.php?...c=98172&hl=

MAFs: http://www.gm-trucks.com/forums/index.php?...c=98171&hl=

So if these are the mods you have, plus an exhaust and a tune from the dealer, and you're dyno shows 353 at the flywheel.... i'd say that's a damn impressive tune you have; you probably don't want to change it.

clayt6499 · March 24, 2010

to be honest as far as actually remapping tunes and stuff on these engines go I know next to nothing. I could stare at a the data logs and things lie the injector curves and not have the slightest idea how to make it better. my friend has been doing this for years. He actually has an 2005 Sierra Denali and His will blow anything I've ever seen out of the water. Hes the guy who did the tune. His Denali Is running a nasty Twin turbo setup and I have absolutely NO idea what kind of power it puts out. but i know its enough to burn break lose the tires at 65 on the freeway... but the reason for the engine being pulled was due to a slight "mishap" with the truck that involved a slight fire...... haha. the reason i didnt go inside the engine at the time of its removal is because i mainly just wasnt thinking about it. and also im not really apt to take these engines apart. I've worked with older carb engines for years and Im not remotely afraid to dive right into one because i know how to adjust those engines to work the way i want to. but there i can see what im doing and do it with my hands. when it comes to mapping computers and PCM's I'm like a 4 year staring at Calculus problems. peak horsepower is produced at around 5315 RPM and peak torque appears around 4755 RPMs. the main reason i feel like the tune isnt as "extreme" as id like it is for some reason the transmission just feels "sloppy". Shift points dont seem right. I feel like the truck shifts a little early under WOT and it isnt anywhere near hard enough. It still has that kinda "laggy" feeling that the stock tune did. Though i did do away with the annoying throttle lag. "when i hit the gas it goes" ;) I'll try to get a hold of him to see what he actually did to the PCM.

clayt6499 · March 24, 2010

Also i can only run 93 octane in my truck right now.... Which sucks for my wallet

clayt6499 · March 24, 2010

Ok so I've been looking around everywhere i can think of and I have come to the same conclusion now as everybody else appearantly has. Based on other reported power gains from tunes, Mine must be something just rediculus. actually kind of worries me now. I like to keep my truck pretty reliable. but other than going inside the engine with porting/polishing, new heads, a cam, or forced induction my goal is dead as it was. well updated goal. get whatever number I can out of it. haha maybe aim for 365 (same as a stock vortec max of the same year as mine). I just want to see how much can be squeezed from the stock 5.3 without going into it. BTW Matt, Looking at my dyno sheet I'm noticing that stragnly my torque curve didnt see the kind of gains that the Hp seem to gain.... which has me a little baffled. Is it possible I've gone a little too far with the wholw "free flowing exhaust" and lost too much backpressure? Or is this a byproduct of the tune? And as for the lack of info about performance mods to begin with i really didnt think the underdrive pulley/MAF would make a big difference when compared to the other 2. And as I said, I dont know much of anything about the tunes and i didnt think mine was anything crazy. But from the reactions I'm getting I believe I have some sort of awesome tune. Which is good to know but sucks because now the easy horsepower gain i thought i could get from a tune is out of reach and sets my goal back drastically. win/lose for me and btw, before I leave one last thing out, the original dyno run was done WITHOUT accessories......

Jennabear · March 24, 2010

What tuning software is your friend using, and who recommended you change MAFs?

Nytemare · March 24, 2010

you'll probably spend less and get more from going inside.

Get a cam and valve-train, port and polish...from a reputable machine shop, don't do it yourself...shave the heads a little for a little more compression, get your self a larger TB and get it dyno tuned or an in person tune...that may get you 350-360, and its far cheaper than spending money on parts that do nothing but give your right ass pocket a weight reduction.

Or you could just toss a 6.0L in there and toss a few bolt ons and a tune at it...that will get you closer to 400 than the 5.3 ever will.

Matt_ · March 24, 2010

best bet would probably be to post up some scans of your dyno charts. There are members here with some pretty extensive experience with 5.3L's on dynos being tuned... i bet they'd be able to answer some of your questions and help out a lot.

Edit: ^^^ there they are

clayt6499 · March 24, 2010

the guy who set up the tune actually convinced me to change the MAF. as for what software he is using and what exactly he did, i havent the slightest idea. ill try to get a scan of the dyno chart up and see if anyone here can tell me whats going on. haha. I knew I was about to get in over my head. and my problem is if i go inside the engine I'm not gonna be able to stop myself from getting the most aggresive cam i can get for the truck. I've kind of got that whole go big or go home syndrome thing sometimes. If i did go into the block, Id easily try to get every ounce of power as is possible from it. Which makes me ask what kind of power can the stock block handle? It's the aluminum block. and also what is the 4 speed capable of handling before i need to beef it up? The more i talk about this the more i want to do it. hahaha. has anyone tried to see how much power can be drawn from the 5.3? If so I want to know how much and what it took to get it. the thing that realy gets to me is knowing there is a toyota truck ot there with more horsepower than my mighty GMC. I want to fix that more than anything. and as for engine swaps, I almost went through with that when the engine was pulled. but i convinced myself otherwise. anyone know what a 6.0L complete runs for these days?

Jennabear · March 24, 2010

I am a tad confused, you also say you are looking into a Predator. As for the MAF, not sure why he would recommend an aftermarket one, since the OEM can handle 550+HP. The aftermarket MAFs cause more issues than anything else and underreport info to the PCM. I would love to see your dyno charts, and am curious as to what kind of dyno your friend was using?

clayt6499 · March 24, 2010

the reason i was looking into a Predator is because I thought that initially the tune i had wasnt anything special and id be able to get more out of the predator. but its not looking that way anymore. as for the dyno we used a hydraulic dyno. Do different dynos affect the readouts?