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NEXT STEP FOR MODS

colton7

New Member
Joined
Aug 2, 2015
Messages
4
Location
South Carolina
Hello guys, so I have already done some mods, as you can see in my signature, but not sure what direction to take next. I have around the ball park of 2k plus or minus that I am willing to spend on mods. Wondering if you guys could help me out figuring out what the best next step is. I am debating getting a 3.5" lift/ level kit off of ebay as well as some 33" mud tires OR going the performance route since my truck is only 2wd. Let me know the best mods I could do for both routes (performance or lifted look) and your opinions on which route I should take. Keep in mind that I am 18 years old and I am about to be attending college in just a couple of weeks. Thanks!
 
First welcome to the site!

People here will gladly help you spend your money so be careful!!....  >:D

Couple things to consider on a lift and bigger tires. You state you have a Z66 AV and I think that comes with self-leveling rear shocks and that may cause issues with air lines and other parts fitting properly. It also affects getting you up into an airstream and could have some effect on gas mileage due to air resistance as well as more rolling resistance of wider/bigger tires. Also if the tires are a larger diameter you will need to reprogram your speedometer or you mileage/speed will be off and could lead to a ticket.
As far as performance mods there are some things you can do but you have to realize the AV is a 6,000 lb. truck with the aerodynamics of a brick so it makes for a poor starting point for turning it into a high performance vehicle. Do you have the stock exhaust on it? Probably the best bang for your buck performance wise would be to get a good CAT Back exhaust system like Magnaflow or Corsa Sport but some performance can be gained from systems like Flowmaster as well they just usually don't come with a lifetime warranty. Do yourself a favor and don't get sucked into the advertising claims on things like a cold air intake, they do make it sound more aggressive but generally won't give you the gas mileage or performance they claim. Some members have gotten improved performance from a programmer.

A lifted AV may cause parking problems with parking garages too.

Being just 18 and starting college you may just want to consider saving your money since you don't know what expenses you may have in college or in your dating life.
Good luck and I hope you have many happy and safe miles in your AV!
 
I'd probably lift it and throw some badass tires on it for 2k. 2k in performance won't get you what 2k will in looks.
 
Vaeagleav said:
First welcome to the site!

People here will gladly help you spend your money so be careful!!....  >:D

Couple things to consider on a lift and bigger tires. You state you have a Z66 AV and I think that comes with self-leveling rear shocks and that may cause issues with air lines and other parts fitting properly. It also affects getting you up into an airstream and could have some effect on gas mileage due to air resistance as well as more rolling resistance of wider/bigger tires. Also if the tires are a larger diameter you will need to reprogram your speedometer or you mileage/speed will be off and could lead to a ticket.
As far as performance mods there are some things you can do but you have to realize the AV is a 6,000 lb. truck with the aerodynamics of a brick so it makes for a poor starting point for turning it into a high performance vehicle. Do you have the stock exhaust on it? Probably the best bang for your buck performance wise would be to get a good CAT Back exhaust system like Magnaflow or Corsa Sport but some performance can be gained from systems like Flowmaster as well they just usually don't come with a lifetime warranty. Do yourself a favor and don't get sucked into the advertising claims on things like a cold air intake, they do make it sound more aggressive but generally won't give you the gas mileage or performance they claim. Some members have gotten improved performance from a programmer.

A lifted AV may cause parking problems with parking garages too.

Being just 18 and starting college you may just want to consider saving your money since you don't know what expenses you may have in college or in your dating life.
Good luck and I hope you have many happy and safe miles in your AV!
would the performance gains of a cat back exhaust with headers & y pipe + tune justify the price of all of it? Also what kind of gains are you expecting from it as well?  and what is the process of acquiring/putting on the tune? I have read that handhelds are a waste of money and to actually get it dyno tuned, but I'm all so new to this and could use a better explanation from a vet like yourself. Also, do you think the full exhaust could be installed by myself and my step father? He is pretty inclined automotively. Any other performance mods you reccomend? I have read things like vette servos and transgo shift kits and torque converters but I am clueless as to what that actually is and price of all of it including installation. Any information would be helpful. Thanks!
 
I can only talk about my personal experiences and I have never spent the money for more mods than I was comfortable loosing in a couple of years due to selling the vehicle at a depreciated price. (I realized early in life that you will only get pennies on the dollar for any mods.)  I also realized that spending money on a depreciating item was affecting my other responsibilities and hobbies in life. (can't do it all so had to pick and choose.)
So once I decided to mod a vehicle I decided to try and spend XYZ amount and get the most bank for my buck. Therefore I discovered that one area that bogged down the AV in acceleration was the stock exhaust. I looked at many makes and decided that I planned to keep the AV a long time and I wanted a system that would hold up to seaside salt air as well as winter road salts, I decided on Corsa on my 2004 AV so I wouldn't be replacing exhaust every couple of years.  I didn't feel the need for a new header or x-pipe since I wasn't building a race truck. The Corsa has been installed by many members in their driveway and it comes complete with all hardware and no welding or bending. You may want to cut stock system off to speed up the install. I just took my 2004 and my 2008 AV to a muffler shop for my installs and both times the shop said it was the easiest install they have ever done. (did it in about 30-45 minutes.) Corsa is also known for NO Drone in the cab so you won't have a headache from long trips or have to yell to be heard. It will have a nice deep throaty sound on acceleration though quiet at cruise. You may find it on  sale somewhere but it runs about $800 for everything from the CATs back. I feel with my butt-dyno an increase in acceleration and Corsa claims I believe about 20 h.p. gain, never had it professionally dyno checked though.
On my 2008 I did get a GM High Performance CAI and all it seemed to do is increase the intake noise at acceleration but no real gain in H.P or MPG. Some members claim the switch of a stock air cleaner to a high flow one from a Z71 AV or a K&N filter to the stock airbox is helpful. (that may be why I couldn't detect a performance gain since my AVs were already Z71 models?)
Some members swear by a tune whether handheld or preprogramed Nelson tune etc. but I never saw the need for a tune since they were expensive and I was happy with my modest gain from the exhaust.
You will have to read the posts of the owners who have installed headers, tuners ect. for the costs of those systems.
When I got my 2004 AV I read on this site where GM has a torque management system to keep owners from trying to smoke the tires and in turn burn out the transmission or some other part of the drivetrain. So in my mind if you add shift kits and other things to bypass the torque management you are going to take a dependable daily driver and turn it into a more powerful but more fragile vehicle that could spend lots of time along the road or in a repair shop. I don't know about you but I need my AV too much to risk having it become unreliable.
Now all that being said if I had the money and no family responsibilities the one thing I would add along with the Corsa exhaust would be a Magnacharger Supercharger. You can even get them with a drivetrain warranty and they will greatly increase your H.P. and Torque yet a cruise you will get good gas mileage. Many members here have them for towing but I think it would be great for making your own SS version AV which GM never made......You could even consider taking it off when you sell your AV if you kept the stock parts to replace, then sell the Magnacharger separately to recoup some of the expense.

Now for the grandfather side of advice, you may want to consider something practical for a mod to your AV like a Bedslide so you can move all your stuff with ease in college or maybe one of the AV bed tents if you enjoy camping .
http://www.corsaperformance.com/searchquery.aspx?year=2008&make=Chevrolet&model=Avalanche

http://www.magnusonproducts.com/p-73-suburban-avalanche-tahoe-yukon-48l-53l-2007-2010-magnuson-supercharger.aspx

Bedslide no longer shows the AV but has a model for Suburbans that has the dimensions that should fit. You may want to call them direct to be sure.
http://www.bedslide.com/
 
In my opinion don't get a catback exhaust by itself as a performance mod - it's a sound mod.  If you want performance from the exhaust pair a catback with headers.

An aftermarket cam will also wake up the truck.  Go big enough and you will need a higher stall torque converter, which will also help to get the truck moving quickly from a dead stop.

If nothing else a handheld tuner is useful for changing the wide open throttle shift points, allowing higher rpms before shifting.  That said if you add much of a cam you are going to need a custom tune.

A supercharger is a relatively easy but not inexpensive way to get a lot more power, typically about a 50% increase can be had without too much reliability issues for the rest of the drivetrain.
 
fishntools said:
Think about it, how can you pass more out, if its not capable of taking it in (same goes for a cam upgrade). Think about upgrading your throttle body and CA Induction to start. Adding a cam; better start thinking about an intk and perhaps some porting.

It all depends upon where the restictions are.  Stock intake and heads are not going to prevent a cam from giving a performance boost.  They will restrict it some, so one would see additional gains with other improvements on the intake side.

fishntools said:
And no matter what you do to increase your volume, you'll need the tuning to fatten your fuel curve/trim. You don't need to hope and poke or throw the chicken bones, volumetric efficiency is an exact science; how do you think they designed your engine?

Tuning with a cam installed is required mostly to increase idle airflow and rpm and very little to correct for fueling.  The PCM corrects the air/fuel ratio based upon O2 sensor feedback.  Volumetric Efficiency table in the PCM is only used below 4000 rpm and even then only during transient conditions.
 
fishntools said:
Agree with the o2 feedback which is why i stated "trim" and yes, i forgot to mention ign timing too.
I guess the moral of this story/thread is...if you want to maximize the return for the money spent to obtain the performance OR reliability desired (cause, ya can't have them both, everything's a "trade off" here) to whatever that level may be, you need to upgrade ALL the links in the chain, and the best way to do so is to calculate, calculate, calculate! Yes/no ???

If one has the money to upgrade all of the links in the chain then your advice is good.  Unfortunately though that's not the case for most of us.  Cams run about $400, a set of good aftermarket heads is going to cost over $2000.  How much either will help depends upon how "bad" the stock pieces are.  Stock cams generally are "bad" due to the car manufacturers wanting nice smooth idle.  Stock heads are generally "bad" due to higher costs to make really good ones.  The gen III heads are fairly good for stock units.  Therefore if one wants to make the tradeoff with the cam then one can get pretty good results.

I'm not sure what you are driving at with your calculate, calculate, calculate statement, and I'm going to disagree somewhat with an earlier statement you made regarding volumetric efficiency as being an exact science.  With the number of variables at play in an automotive application (air temp, engine speed, and desired power output level being the primary ones) using scientific formulas have their place but in the end tradeoffs have to be made and that is where the science stops and preferences take over driving individually chosen modifications.
 
fishntools said:
If the OP doesn't have the ability to process and map these numbers I'm sure there's a program out there to do it for him. (Somebody please post link if you know of any) Input the cuin.spec.s of the cam (stock or otherwise) and determine the how much air a cylinder will flow at idle

There isn't such a program.  Why, because you aren't taking enough variables into consideration.  At best you will get a ballpark but why get ballpark theoretical data when empirical data is available from this community.

There are people out there that have spent money foolishly - that is true.  OP posted here because:

a) he doesn't want to waste money
b) he wants advice from folks who have figured out ways to spend money productively
c) he doesn't know how to engineer it himself or at least wants to get another opinion or two

Telling him to engineer it himself isn't being very helpful.    :cool:

If you want to give advice he can use then please do.  Otherwise please let those of us who have spent the money to let him know what works well and what doesn't.  (y)
 
Nice chart, but it would probably steer someone to spending money foolishly than wisely - it just isn't real world.

Airflow correlates very well with horsepower.  Not too many engines have straight-line horsepower curves.

Please stop pissing in the well so that people that have made performance mods can feed this guy's thirst with experience and not your theoretical first-order calculations.
 
fishntools said:
First order's all that required here, I don't get the money foolishly or it 'isn't real world' part though ??? Engine=positive displacement air pump = cuin IN=cuin OUT. CFM vs. RPM is all you need to consider for intk and exhaust mods the ECM handles the rest.Shouldn't under-estimate the OP ability to grasp that.

Glad you straightened me out.  Since you've provided all the info that anyone who wants to know what performance mods work and what don't I'm going to save this thread to my favorites and point all further inquiries here since you have provided the ultimate answer.
 
Hey guys, after a lot of looking, finally bought my supreme suspensions 3.5"x1.5" lift/leveling kit. I had it installed at my local auto shop and WOW! I love the way it looks! not sure how to post pictures, so if one of you guys can help me with that then that would be great. Might get some new tires in a few months. Opinions on size, brand etc.? Thanks!!
 
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