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I am considering putting a K&N cold air intake and a Magnaflow exhaust system on my 2008 Silverado 4 wheel drive w/ 5.3L engine.
My question is for anyone who has done one or both of these upgrades- do you get the added performance and increased mileage that both manufactures claim? I use this truck for towing my boat and will be making a cross country trip towing a cargo trailer, so I am looking for any performance/mileage help I can get. Also what about putting a new performance chip?
Thanks in advance for any info.
Dilligara
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The air intake is engineered to reduce noise. Removing it with and replacing with good quality pieces should help. Exhaust the same. You don’t want to put a Chip in that, or things of that nature. Have it dyno tuned after your intake and exhaust and that should help it a bunch.
How does one dyno tune a vehicle with non-programmable factory engine management? I was going to say to start with a chip so that any future mods have some hope of being properly taken advantage of and opening up the possibility of tuning. I’d be happy to be corrected on this logic, however.
I have an AEM cold air and there’s a definite difference between that and stock. The couple of times I’ve had to take it out and reinstall my stock intake, I immediately notice slower acceleration, throttle response, etc.. Then when I put the AEM back in, I can tell the performance is back as soon as I take the car on a drive. Also, not sure if this is true or just my imagination, but the exhaust note seems a little deeper with the intake. I hear from everyone that cold air intakes will do that, but who knows. Maybe it’s just ricers trying to make themselves feel better about their fart cannons. In terms of mileage, I’m really not sure. I haven’t kept track of my spending at the pump w/ and w/o the intake, but based on the logic of cold air holding more oxygen therefore producing more power with less fuel blah blah blah I wouldn’t be surprised if it does in fact improve fuel consumption. & I agree with fopeano on the tune. Your local performance shop should be able to answer any questions you might have on that.
On a side note, your CEL will most likely come on and give you a code for your MAP sensor. This is just because your computer is detecting a change in pressure in your intake manifold, simply because you’ve installed a new intake. Ignore it for about a week or two and the sensor will adjust to the new pressure and turn off the CEL, or you can just clear it yourself if you have a scanner
[quote=”Fopeano” post=130993]How does one dyno tune a vehicle with non-programmable factory engine management? I was going to say to start with a chip so that any future mods have some hope of being properly taken advantage of and opening up the possibility of tuning. I’d be happy to be corrected on this logic, however.[/quote] Correct, tuning/ a performance chip is necessary to take advantage of all the available power. I had the exact truck(minus the 4wd and 5.3), with the 4.8 V8 AND K&N intake and magnaflow catback exhaust were my first two mods.
I then proceeded to chip it, add a cam a performance transmission and high stall converter.Point being, the K&N AND Magnaflow didn’t do much, I wasn’t satisfied. intake temps went down maybe 1 degree. Fuel mileage was the same. The chip added some great power, and I futhered my ambitions and tuning with a cam and a loose converter/built tranny combo.
A catback exhaust is just for show, it really doesn’t do much to free up flow, your biggest restriction is the y pipe and with that still in place, any mod is meaningless.
To the other posts on this, from the GMT-800 on, the airbox is overcapacity so there is no extra air flow. The K&N doesn’t reduce intake temps on these trucks because of the way the stock assembly is designed. The stock assembly actually is quite good on the trucks, not in the looks department, but performance wise absolutely. The biggest restriction to volumetric efficency on these trucks IS the cat y pipe.
All throughout college my goal was to make my truck better and more powerful to compete with my classmates as we were in an automotive program. I know these trucks inside and out.One more thing, the 4L60-E tranny WILL be the weak link in this setup. Hence why I put in a build unit. The 4L60-E in stock form really is only good for 400 ft lbs of torque and even that is pushing it. Having 4WD may compound this weakness due to the extra weight
The biggest increase you can do relatively cheap is to upgrade the exhaust manifold and converters, as stated by others any upgrades after these is mostly for show. Other than that it gets expensive when going into the engine/engine management and transmission.
As for the intakes, it depends on just how restrictive the O.E. setup is but generally the origional setup is pretty good by 08′. It gets nice cold air from outside the engine compartment so I would leave it alone for now.
You can do more for your truck by keeping it tuned up and change all of the fluids regularly.
That truck is like the other Gms of the vintage where the factory ecm can be reflashed with a number of different software programs. Dyno tuning this way will gain power, mods or no mods. You can also get emissions codes and garbage like that removed when having it tuned/flashed. Don’t waste you money on power programmers, piggy back modules, that type of stuff. Just get it reprogrammed
The claims are meant to sell the products. Any results will not be noticeable except as a placebo effect.
You will not get a CEL from either of these mods, to clarify. I do not recommend getting a tune first. Getting a tune first without knowing how far you are going to go with physical mods is not smart. Call Blackbear up when you know what you want to do, they are excellent and they have the results to prove it. You need to swap out the y pipe, I can’t stress this enough. With the exhaust for max power you need to go headers back. Take a good look under your truck at the exhaust system. Look from the manifold to the cats, see that pipe that the cats are on? Ya thats no good…take it out. You can use the original cats, just separate the pipes and put an X pipe in to balance the exhaust out. The y pipe will choke the engine at higher rpms.
I think u/SacTownTuner kinda nailed it. While upgrades like a tune and exhaust might not give you a noticeable increase in power they should increase things like throttle response. As far as tuning there are several companies making plug and play programmers/tuners. At +/- $500 it might be your best bet as an early step, I think some of them are user tunable and they can re-flash the stock parameters if you ever start having a weird issue that requires diag.
With something as mainstream as an 08 Silverado with a product from a manufacturer as big as K&N there really shouldn’t be any issues. They’ve probably sold thousands of them and one would hope that by now any engineering issues have been worked out.
Where would a person go to get it reprogrammed. Is this something the dealer would do, or do I go to an independent repair shop, performance shop? I live in the Minneapolis, Mn area if anyone has knowledge of shops in this area that would do this work.
You would need to have a tuning shop do it or send your PCM out to a tuner to be reprogammed/flashed. This is the kind of thing the dealer would tell you not to do, and a typical independent doesn’t get involved with that kind of thing. The type that can do that is a bushiness that deals specifically with model of truck or engine AND does modifications/tuning.
Once you start doing this kind of stuff, having your truck repaired at shops may also get trickier. Plenty of places are fine with it and especially like it when you tell them upfront about mods. Some places, and most dealers, will not look favorably on mods or know how to deal with them. With a PCM flash, any factory reprogramming for a service campaign or recall will either not work or overwrite it, and GM does a lot of that. It also makes check engine light and drivability diagnosis more specialized, and mechanics get pissed when they spend a bunch of diag time to find out it’s flashed (something they need to know) and have to work from there. Just some caveats to consider.
Take it from someone who has extensive experience with these trucks, a CAI is a waste of money. for 300+ bucks you can get a good tune or do the tune yourself for $100. Here, I’ll help you with your search for tuners:
http://www.blackbearperformance.com/ < I highly recommomend. They will give you a tune custom tailored to your application. http://www.hptuners.com/ < If you want to fine tune it yourself and know what your doing http://www.hypertech-inc.com/
I have an entire notebook of realworld data coming from dragstrip data calculated as well as dyno comparison sheets before and after specifically with LSX based cars. This goes back 11 years for me as far as data gathering. The only thing I didn’t not come up with an exact gain per mod, because some were done together and thus we could not pinpoint which mod did what, just a series of mods – vs either dyno numbers in torque or in the case of dragstrip time, the MPH, not the et is indicative of horsepower. I can tell you for absolutly certainty that GM air intakes do restrict to some degree, but its not like you are going to gain 30hp at the rear, its more like a few. But remember, if you do tens mods worth 5 hp, thats 50 horsepower. I started with Tunercat myself and then my dyno and guy eventually moved to from LS1edit to the current HP tuners, which is great. In our area my tuner and I eventually set the track record for mods vs cash, but it took much dyno tuning and some very sharp tuning. As far as factory ecm flashes vs guys that actually tune for power, well there is no comparison there. You need to hook up with a professional tuner with a dyno to set the trims and timing to optimum power, which is certainly totally different than the stuff GM put in there. Purge can codes, rear O2 sensors, in my case a thing called CAGs and a whole bunch of garbage went away. When swapping gears or tire sizes, an aftermarket tune is pretty much essential. If you do things to really increase airflow like gutting mafs throttle body modes, injector size upgrades, the entire timing and fuel map has to be revamped or you will never see any gain.
As far as dealerships go, and serviceability, well I speak with one of the top GM Tech trainers in the country all the tim, and one time I mentioned ECM hacking for power, and he basically stated that he doesn’t condone it, know how to do it, or want to know. On my own with that, however a good tuner will almost always be able to repair your issues better than a dealership anyway. I was involved with a corvette project that had a procharger on it, and when it was first set up, it was upgraded to 42lb injectors, cam, bunch of other stuff. Factory tune it would’t even idle. Took it took a tuner and made ungodly high power. 700+hp with a sharp professional tune. Then it went for a recall for an igntion switch, the GM fools working on the car reflashed it back to stock. The pig rich non idling condition came back and they didn’t know what the hell to do (car wasn’t even driveable), so he had to have it tuned again, and sure it enough, it was back to it’s old self, ran much stronger than anything the factory would have made. The people working it to make it run right, and not to a bunch of EPA and noise standards knowledge was far beyond what any dealership could do.
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