Free horsepower

[Chris99Z71]

Maybe I missed this and someone has already written about this, but here goes...

On the NBS trucks (I know this is atleast true for the 5.3), right behind the throttle body on the passenger's side of the intake there is a tube from the EGR that sticks into the side of the intake. In fact, it sticks TOO FAR into the intake...
Take out the bolt from above the tube.
Unbolt the apparatus at the other end of this tube from the front of the passenger's side cylinder head (2, 15mm bolts).
Unplug the wiring harness from the top.
Remove the two bolts (10mm) that attach it to the exhaust manifold and save the gasket that's in between. This is most easily done from reaching over the top of the tire, working through the fender well (atleast this is the case with a 3" body lift with no lift lips... :)).
Now, you can remove the whole do-hickey.
Back to the tube that sticks into the intake...cut off the end, just past where it tapers down, this sounds vague, but it's pretty obvious when you look at it.
Now re-install the whole thing.

OK, next step. There is a small hose (slightly bigger than windshield washer tubing) that runs from the radiator to the bottom of the throttle body. Remove it from the throttle body end.
On the opposite side of the throttle body, there is another short piece of tubing that goes from a nipple on the intake (I think..can't remember) to the throttle body. Completely remove this piece of tubing and discard it.
Run the longer piece of tubing straight from the radiator to the nipple on the intake.
I believe that GM originally intended this to initially warm the throttle body for cold starts, but unfortunately, it continues warming the throttle body when the engine is hot, along with all fo the air that passes through it! However, since doing this, i've had no probs with cold starts even when it's well below freezing.

All of this can be done in less than an hour and I would bet it would free up somewhere between 5-10 HP...but, it's 5-10 FREE HP!

Bango!....Free horsepower.

[azwiley1]

I know this is a rather old post, but I just came across it. I did have a few questions for you though. I have a 99 Z-71 also and looked at the second part. I found the hose from the radiator to the TB, then there is a hose on the top right corner of the TB to the head (not the intake) is this the second hose you were refering too? On the TB, what did you do with the two open nipples? Leave them open or cap them with something?

[Country]

doesnt work on the 4.3 f/s

[nowNzen]

Thanks for sharing the knowledge, Chris. Good mods & the price is right! :head:
I read somewhere that the EGR tube does not intrude as far into the intake on '03 5.3s. Is that true?
Also, is the throttle body 'heater' set up the same on the '03 models?

[2K5Squirrel]

does this mod work on '04 5.3's

[Kevellis32]

Will this work on a 95 5.7?

[jocww]

will it work on a 02 tahoe. should shouldnt it. you should post some pics.

[deltron]

Originally posted by DanaliHD
I think this mod is on installuniversity.com, but they did it on a camero. I might be wrong.

it does look like its on there. I wish I had read the install university docs first, particularily because of this step:

This next step is very critical! Please pay close attention! You need to use extreme caution when tightening the EGR pipe back up to the intake manifold. DO NOT tighten the bolt over 89 in-lb or YOU WILL STRIP the brass heli-coil out of the manifold! See Figure 10 for that end result.

luckily, nothing went wrong, but that could have been a very pricey mistake ($1000).. So guys if you are planning on doing this mod, do yourself a favor and read the instructions on installu first.

link: http://installuniversity.com/install_university/installu_pages/sophomore_year/egr_free_mod.htm

[ArrivalSS]

Originally posted by Kevellis32
Will this work on a 95 5.7? No. TBI engines don't use a throttle boby heater. They use a pre-heat tube like the old carbed engines. Good tip. I may do it on my wife's 00 Tahoe. My favorite four letter word. FREE. :D

[DarkFox1]

old thread and its very good, but just wanted to add.. according to a few websites this TB bypass has been "dyno proven" on ls1 camaros to do 6.3HP and like 7 TQ. I doubt its this high in most circumstances, but I just wanted to add that. As far as the EGR, newer NBS trucks do not have it at all.. unless maybe for certain emissions requirement states. I imagine bypassing the EGR adds more than the TB bypass however, since from the looks of things it just pumps hot exhaust gases into your intake, along with any unburned already heated gas, and partially blocks the airflow.

Just a little I felt would be helpful to the thread.

Btw, another option, some of you may notice the TB has an inlet and outlet and 2 hoses.. 1 from the steam valve and the other to the radiator, what I did was went to the hardware store and bought a double nipple setup thats that size and just connected the 2 hoses together, no stretching the hoses to maximum distance, it seems if you did this the other way the hose might be a little tight.

not FREE then.. but its like.. $1.50.. you got that between the seats hehe

[RandomHero]

will this make the engine sound louder? I hope so cause then im doing it

[13dually]

is it even nessessary to have at all i assume it just resirculates into the block again can the line be capped on both sides intake and rad.?

or is it pressurized to the extent where it would just blow it out?

[DarkFox1]

my understanding of the function is that its the "steam lines" for the heads, they are at the 4 corners of the heads under the intake manifold to keep from getting hot spots, or at least tahst what my street and performance video said. you probablly COULD cap it.. but I'm not sure you'd want to.

[hyeride00]

is there any way you can post a pic of what you did? I have my water pump off right now and want to do that before i put everything back together.

Thanks,
Matt

[Devildog240]

will his work for the 2000 silvy 2500 with the 6.0L ?

[03WhiteZ71]

any pictures or anything for a 03+ I did this on my Camaro SS I had two years ago, but I don't rememeber exactly how I did it, and it doesn't look the same under the hood of this truck. Any install pics would be appreciated.

[BadBowtieBoy]

Do you have any dyno results to prove the 5-10 hp gain? I would like to try this on my 05 Silverado but am sceptical.

[13dually]

i doubt anyone dynoed that mod just to check, dyno runs are costly

[TikiClub2]

5.7L Vortec?

[99-2door]

5.7L Vortec?

NO

[jimpbmw]

hi Chris,
I have a 2002 Silverado with the 4.8 in it and was wondering if these issues are the same on it as on yours. Thanks for the info in any case. Jim from Vermont

[94_chevy]

will it work on a 94 5.7L

[00chevy4x4]

will it work on a 94 5.7L

No.

[Jwalker]

2 questions.

1. The way the EGR noid is made, it almost looks like it was made specifically to catch the incoming air. If you cut the bottom part off, you are losing the peice that "catches" the air as it's forced through the throttle body. Does this cause any issues with the emissions hardware? Fuel milage or drivabilty issues?

2 Does this mod work for the 2004 5.3?


Thanks.

[Zack'sZ71]

i did the TB bypass on my 95 Impala SS and I don't think that it gave me anywhere near 5-10 HP. I couldn't even really tell a difference in SOTP feel and that is where you will notice HP. I would say that it probably gives you 1-2 HP. I don't know how to explain it but it affects your open and closed loop settings too. That is what all the engine gurus on www.impalassforum.com say. Go onto that site and search for TB bypass and you will find all the info you need to know about it. There are some supersmart individuals when it comes to GM engines on that forum. Everyone I know highly recommends doing the TB bypass.

[dzuni3302]

i did the tb mod in less than 15 minutes and noticed a slgith difference in response. Also descreened maf and egr mod, noticed good gains, great for the price, and theyre all free.

[Z71_Offroad]

install pics??? please

[bonestockracing]

The TB bypass mod???

Dont you thonk that it would be bad for a cold climate ( Throttle plate Iceing) or is it just me and wouldnt it end up hurting your gas mialage B/C you are in open loop longer???

Just woundering...

[jdh2005]

if you do the TB bypass mod and live in an area where the weather is extremely cold in the winter, you need to undo it before winter hits, in the summer this mod is great and will free up some hp, but in the winter it will cost you hp and fuel economy

[rickylea]

great tip my truck screams when it's cold but as it gets hot you can tell :dieclown:

[jdh2005]

you may also try polishing your throttle body, did this and noticed considerable gains

[TheBigRedZ71]

2 questions.

1. The way the EGR noid is made, it almost looks like it was made specifically to catch the incoming air. If you cut the bottom part off, you are losing the peice that "catches" the air as it's forced through the throttle body. Does this cause any issues with the emissions hardware? Fuel milage or drivabilty issues?

2 Does this mod work for the 2004 5.3?


Thanks.

1. No, did it to 99 Sierra 5.3 last week and no lights have come on, drives the same as it did before, and gas milage is about the same.

2. Yes (or at least pretty sure)

[RIPBoyd]

Okay 1. Does anyone have any pictures because I see every tube that I believe is being described but I really don't feel like messin with stuff if im not sure and 2. Why do you have to remove the entire gadget attached to the exhaust manifold if your only cutting the end of the tube attached to the TB?

[TheBigRedZ71]

Okay 1. Does anyone have any pictures because I see every tube that I believe is being described but I really don't feel like messin with stuff if im not sure and 2. Why do you have to remove the entire gadget attached to the exhaust manifold if your only cutting the end of the tube attached to the TB?

I dont have ne pics, sorry. I didnt remove the whole unit, i just diconnected the egr valve (removing the air filter assembly makes it a lot easier) unbolted the bracket that connected to the TB, threw a blanket over the engine, took a cutting wheel and cut right through it, bolted everything back up, re-routed the hoses and bingo i was done. took about 30mins start to finsh. ill try to post some pics of the after.

[RIPBoyd]

Yeah if you can post some pics cuz i understand what you're sayin but like i said, i dont wanna make a mistake you know...better safe then sorry especially with my truck...just post up pics when you can...

[SupermanSS]

:55:

[lotsofmud400]

I unhooked the two hoses on our 03 5.3L suburban and connected the two hoses with copper tubing.

Another suggestion was cutting out the mass air flow screen right behind the air filter (We got a K&N). Keep in mind when you do this, dont touch the sensors behind the screen. It took around an hour to do these two things. With both mods, doin 75-80 mph fully loaded we averaged 18 mpg. Before the mods, we only got 16.

[GIMECHANIC_454]

what about the 7.4L Vortec?

[RIPBoyd]

I was still wondering if someone could post pics (5.3L) so that I can rest assure I am doing the right thing and cutting the right hoses...thanks

[westcoastsailor]

there isn't an EGR on '04

[BassBaller5]

Im goin to assume it works with a 03 4.8L since their practically identical to the 5.3. This is a great idea for people that want power and are short on cash... its sounds complicated but if you have a basic idea at what your doing it shouldnt take long.

[east1la]

will this work on a 2003 chevy silverado 5.3?

[98withbang]

and dont forget the homey com in the intake at the mafs just be careful not to mess up the mafs then that horsepower costs alot more did the 2 mentioned previously and the honeycomb all at once and there was a plenty noticible differance if you have the throttle body looking out the front of the truck then all of the listed are possible

[EscaladePatrick]

Will this work on my 2004 6.0 Escalade? I have a K&N cold air on now, and I don't know if that will affect the application.
I am good at following directions, so I'm confident that I can complete the mod, but I don't know that much about engines and engine lingo, so I don't know what exactly what the Escalade engine consist of.

THANK YOU FOR ALL YOUR HELP