How much power will my truck make after these mods?

[Jeremiah_Yukon02]

Ok so I have a 2002 GMC Yukon 5.3 LM7, I think the stock power rating is 285?, Where do you think I'll be with a few bolt ons like, Shorty Headers, High Flow cats, catback exhaust and a blackbear tune?


145k Miles.

 

[Joseph Garcia]

Are you staying on 87 octane? If so, my non-professional guess would be up to 25 additional HP.

Other members on this Forum that are much more knowledgeable than me will chime in.

 

[Mudsport96]

Shorty headers.. 4 to 6 hp ( dyno proven compared to manifolds)
cats i think negligible as properly functioning stocks should flow more than a 5.3 can use.
Catback would be the most beneficial with a tune.
I say 20 at best.
Header dyno results manifolds vs shorties vs long tubes

 

[Tonyv__]

Ok so I have a 2002 GMC Yukon 5.3 LM7, I think the stock power rating is 285?, Where do you think I'll be with a few bolt ons like, Shorty Headers, High Flow cats, catback exhaust and a blackbear tune?


145k Miles.

slap a cam in there and you’ll really wake the engine up.

 

[Jeremiah_Yukon02]

slap a cam in there and you’ll really wake the engine up.

If I'm gonna do a cam something I'm worried about is reliability and also paired with all those mods plus the mild cam how much hp do you think I'll be making?

 

[Mudsport96]

If I'm gonna do a cam something I'm worried about is reliability and also paired with all those mods plus the mild cam how much hp do you think I'll be making?

Look up Richard Holdener on youtube. He has hundreds of dyno videos.

 

[OR VietVet]

I recommend making sure the engine is ready for the HP pop up. Do a compression test to verify all is good. I recently had a free BBP tune done and it really woke up my engine when accel and the transmission shifts are firmer but I had done a recent compression test during my build thread and knew all was good. You could also do these upgrades in stages.

 

[Tonyv__]

If I'm gonna do a cam something I'm worried about is reliability and also paired with all those mods plus the mild cam how much hp do you think I'll be making?

I have no comment on the HP question because I don’t have an answer for you. But I suggest the cam because all the mods you listed will get you nothing more than a screaming truck with barely any increase in performance

 

[tom3]

Son had an 06 Siverado with your same drivetrain. He put a cold air intake on it that probably gave no real power increase but really had a nice sound. Premium gas and a tune of some sort did make some more power by the seat of the pants dyno.

 

[OR VietVet]

Something else to consider thru all this. As you continue to do this horsepower increase and if you go even further, you need to make sure some other systems are up to *s*n*u*f*f* for the increase. First in line is brakes, you can go fast but you gotta STOP. Next is steering and suspension, so that the handling can be safe during the HP runs. Make sure the cooling system is clean and flowing great and being cooled properly. Is the transmission in great shape and do you know when the last time it was serviced and what was done during that servicing. Rear diff comes to mind. Fluid condition/age and gear lash and sight inspection of the guts.

What in the name of the Wide Wide World of Sports is going on here? The word s*n*u*f*f gets the asterisk treatment?????? C'mon man!!!!!!!!!!!

 

[Tonyrodz]

Something else to consider thru all this. As you continue to do this horsepower increase and if you go even further, you need to make sure some other systems are up to ***** for the increase. First in line is brakes, you can go fast but you gotta STOP. Next is steering and suspension, so that the handling can be safe during the HP runs. Make sure the cooling system is clean and flowing great and being cooled properly. Is the transmission in great shape and do you know when the last time it was serviced and what was done during that servicing. Rear diff comes to mind. Fluid condition/age and gear lash and sight inspection of the guts.

Excellent point. After my cam/motor install the 1st thing to go was the trans. Couldn't take it lol. Our transmissions aren't known to handle a lot of power stock.

 

[corvette744]

I have no comment on the HP question because I don’t have an answer for you. But I suggest the cam because all the mods you listed will get you nothing more than a screaming truck with barely any increase in performance

Exactly just more noise and alot of money spent.

 

[iamdub]

Exactly just more noise and alot of money spent.

But louder makes you think it's faster. Paint that Hot Air Intake red and you'll have all teh VTECs.

 

[MassHoe04]

I would really love to do any or all of the above-mentioned performance mods!
Then, back to reality for me.

I think of having to do things like front CV axles and whatever else might come up that is needed to keep it on the road.

The thought of spending thousands for performance mods on a 207k+ mile truck, only to risk blowing up something critical... Just something I can't even think of risking.

Maybe someday, I'll have enough money to play with for fun, instead of always having to grind just to hold things together.

I do enjoy seeing all the cool and fun things many of you are out there doing. Appreciate all the interesting write-ups and ideas! Keep'em coming!

 

[Rocket Man]

The tune is the only thing on that list that will make much difference and if it was my money, that's the first thing I would do. Shortys don’t do a thing on these trucks, and the exhaust will just make it sound better. A cam is the next best bang for the buck and can net quite a few hp depending on which one but if you’re gonna do that, do it before the tune or have provisions to update the tune via an Autocal or similar since the tune will have to be adjusted for the cam. Like others have said, the trans needs to be fairly solid or else it won’t last long after you start adding power so just keep that in mind- you can’t just start beating on it or it will fail if it’s weak.

 

[Donal]

Ok so I have a 2002 GMC Yukon 5.3 LM7, I think the stock power rating is 285?, Where do you think I'll be with a few bolt ons like, Shorty Headers, High Flow cats, catback exhaust and a blackbear tune?


145k Miles.

If the vehicle has the "Tow/Haul," function, drive in the tow function for a few days and the engine will be up the horsepower curve a bit and see if you like additonal performance. You can keep a log of the rpm range that you use daily in standard mode and then in Tow mode. Then you will have a the RPM range to target for improvement.

 

[Alex_M]

In truth, if you're wanting more of a kick in the pants on the street then you might just look at regearing the truck. A lower ratio (higher numerical number) differential gear will net your drive peppier on the street more noticeably than any of the mods you mentioned.

Torque in the lower RPMs is more what makes your vehicle feel peppier on the street, not horsepower (at the higher RPMs) as much. This is an oversimplification as both are measured across the entire RPM range, but generally gets the point across. The lower gearing will give you a bit more mechanical advantage and give you more effective torque output at the wheels.

There are a couple cam options that will keep the low end torque for the street and add some horsepower on top, but you'll only feel the difference if you're revving your truck out regularly. If that's something you're interested in then the Richard Holdener recommendation is a good one. Pay close attention to the RPM range you usually drive in, and what RPM range his tests show power gains (and losses). As a general rule of thumb, you will barely notice any difference if any at all at less than a 20hp gain. For a noteworthy "seat of the pants" gain, you're looking for 30-40hp gains.

The 15-20hp gain estimates with tune, shorty headers, exhaust, are roughly accurate. Most will be on the lower end of that spectrum, and all the gain will be in the higher RPMs. On the street in your normal RPM range you will get 0-5hp gain (from the mechanical upgrades, talk about tune further down) due to the air flow demand being lower. Removing your catalytic converters or going to a "high flow" converter will net you zero gain. All modern catalytic converters are "high flow" since the mid-90s, and do not provide a noticable change until you get in the 600-700hp range. In fact, with aftermarket converters you may actually impede the exhaust flow due to the transition between the straight pipe and the new converter (again, a near immeasurable amount) not being as smooth as that to and from the factory catalytic converter, and creating turbulence in the exhaust system around those transitions.

Making notes on the tune specifically, you are not likely to unlock much extra horsepower from a mail order tune, but will notice some seat of the pants improvement for the same reason you will notice an improvement with a gearing change. The tuners generally change your transmission shift pattern to hold the truck in a higher RPM range making more effective use of the power at the trucks disposal. If you get a talented tuner to tune your truck in person, there are a few stray horsepower that can be unlocked.

So in summary, your most noteworthy return is probably going to be a gear change plus a tune. Remember if your truck is 4wd, you need to change the front differential gears at the same time.

 

[Trilla_one]

In truth, if you're wanting more of a kick in the pants on the street then you might just look at regearing the truck. A lower ratio (higher numerical number) differential gear will net your drive peppier on the street more noticeably than any of the mods you mentioned.

Torque in the lower RPMs is more what makes your vehicle feel peppier on the street, not horsepower (at the higher RPMs) as much. This is an oversimplification as both are measured across the entire RPM range, but generally gets the point across. The lower gearing will give you a bit more mechanical advantage and give you more effective torque output at the wheels.

There are a couple cam options that will keep the low end torque for the street and add some horsepower on top, but you'll only feel the difference if you're revving your truck out regularly. If that's something you're interested in then the Richard Holdener recommendation is a good one. Pay close attention to the RPM range you usually drive in, and what RPM range his tests show power gains (and losses). As a general rule of thumb, you will barely notice any difference if any at all at less than a 20hp gain. For a noteworthy "seat of the pants" gain, you're looking for 30-40hp gains.

The 15-20hp gain estimates with tune, shorty headers, exhaust, are roughly accurate. Most will be on the lower end of that spectrum, and all the gain will be in the higher RPMs. On the street in your normal RPM range you will get 0-5hp gain (from the mechanical upgrades, talk about tune further down) due to the air flow demand being lower. Removing your catalytic converters or going to a "high flow" converter will net you zero gain. All modern catalytic converters are "high flow" since the mid-90s, and do not provide a noticable change until you get in the 600-700hp range. In fact, with aftermarket converters you may actually impede the exhaust flow due to the transition between the straight pipe and the new converter (again, a near immeasurable amount) not being as smooth as that to and from the factory catalytic converter, and creating turbulence in the exhaust system around those transitions.

Making notes on the tune specifically, you are not likely to unlock much extra horsepower from a mail order tune, but will notice some seat of the pants improvement for the same reason you will notice an improvement with a gearing change. The tuners generally change your transmission shift pattern to hold the truck in a higher RPM range making more effective use of the power at the trucks disposal. If you get a talented tuner to tune your truck in person, there are a few stray horsepower that can be unlocked.

So in summary, your most noteworthy return is probably going to be a gear change plus a tune. Remember if your truck is 4wd, you need to change the front differential gears at the same time.

Not really sure if my issue is related but sounds close. My mostly stock 07 Tahoe makes good power but I feel like it doesn't hold the RPMs high when shifting from 1st to 2nd during hard launches. It's almost like it drops and has to start over. If i'm already in a higher gear and floor it I get a lot more out of it. Anyone have any ideas?

I was never really interested in making this truck" fast". I just wanted it to be capable, which it is. I got the Diablosport tuner to turn off AFM which was starting to cause problems at 225k miles(now at 243k). As a bonus I was also able to do the 87 octane tune and remove the speed limiter. The latter of which was only an issue sometimes making the 300 mile trip to Miami.

 

[Mudsport96]

Not really sure if my issue is related but sounds close. My mostly stock 07 Tahoe makes good power but I feel like it doesn't hold the RPMs high when shifting from 1st to 2nd during hard launches. It's almost like it drops and has to start over. If i'm already in a higher gear and floor it I get a lot more out of it. Anyone have any ideas?

I was never really interested in making this truck" fast". I just wanted it to be capable, which it is. I got the Diablosport tuner to turn off AFM which was starting to cause problems at 225k miles(now at 243k). As a bonus I was also able to do the 87 octane tune and remove the speed limiter. The latter of which was only an issue sometimes making the 300 mile trip to Miami.

Well there is a hell of a gear ratio drop between 1st and 2nd. So your rpms will drop really far on that shift. From a 5500 at 45ish in first to 3000 in second. Now at highway speed going to pass, you will drop to high 3000s to mid 4000s depending on speed. So it will feel like there is less of " a loss of power". When in reality you are just dropping into the meat of the power curve. Instead of below it and having to get back to it. And I am assuming that you haven't made a full throttle 2nd to 3rd shift, as that is WELL into triple digit speeds. But, it would still drop to 3600ish rpm and feel almost as lazy as the 1-2 shift does.

 

[strutaeng]

Well there is a hell of a gear ratio drop between 1st and 2nd. So your rpms will drop really far on that shift. From a 5500 at 45ish in first to 3000 in second. Now at highway speed going to pass, you will drop to high 3000s to mid 4000s depending on speed. So it will feel like there is less of " a loss of power". When in reality you are just dropping into the meat of the power curve. Instead of below it and having to get back to it. And I am assuming that you haven't made a full throttle 2nd to 3rd shift, as that is WELL into triple digit speeds. But, it would still drop to 3600ish rpm and feel almost as lazy as the 1-2 shift does.

Would an 07 Tahoe be a 4L60e-variant or a 6L80?

I can never get when they switched over the transmissions. I originally thought it was when they switched body styles, but I don't that's true, right?