Lost Some Low-End Torque...

[BlackThunder96]

I had lost some low-end torque when i got my true dual exhaust system w/out cats and i don't know why i didnt think about it before..., so now i want it back without changing my exhaust a whole lot. I was thinking Thunderbolt cats (just ordered), a flex-A-lite fan, hypertech programmer, and edelbrock headers?...Any other options anyone has and would do in my situation??

[SuperStepside]

Should've done some research on here. Plenty of info that could've changed your mind about no cats and true duals.

If you want your torque then get long tube headers. Put your cats back on. Magnaflows are good. Flex a lite wont do good unless it's electric fans.

[Outlawz2004]

magnaflow mufflers would work. Also, dont do a programmer.Get a custom tune, cheaper and more power. This will also help get your truck back running strong after the exhaust you put on.

[GreaseDog]

depends, what size duals did you go with?

[GMC Era]

What size pipes you got? (ok, that didn't sound right but you know what I mean!) If they are 3", swapping to 2" after the mufflers will give your low end back.

[BlackThunder96]

i actually was looking at tunes, which ones would you go for? And my piping is 2.5" and my glasspacks are 9" long...

[Outlawz2004]

I have a Wheatley tune gowheatley.com
Others are blackbear and Nelson. There are others as well, but these are the popular ones.There is also wait4me, but they are hit and miss kind of tuning.

[BlackThunder96]

oh ok, how much would they cost? Also, why a tune and not a programmer?

[Outlawz2004]

Wait4Me is cheap, only $75 I believe. Havent checked in a while. Mine(Wheatley tune) was $250 but he has gone up on them. Most range from $200-400 for a mailorder tune. I think for your model truck they are cheaper though just go to his website, gowheatley.com

[1989K1500]

Blackbear tune.

[BlackThunder96]

sounds reasonable..., why choose a tune over a programmer though? more hp & trq? Im looking not only for them but for better gas mileage, and since i got bigger tires, so i'd have to calibrate for them as well...I was looing for a hypertech programmer....

[Outlawz2004]

I had a hypertech. They are decent but cant compare to a custom tune. The best mileage I ever got with the programmer was 17, with the custom tune I get 18-22 depending on how I drive it. YOu will get more power and have more adjustability with a custom tune over a programmer. Also, custom tunes are usually cheaper than programmers. Programmers sometimes lock up causing it to be unusable or your truck to not be driveable.

[GMC Era]

From all I've read the hypertech sucks. If you go with a programmer go with the Diablosport Pradator. It lets you change alot more than the other ones and you can also have a custom tune loaded onto it later if you choose.

The custom tunes will probably be better for you though, because they can tune it more specifically for your exhaust setup, correct for your tires, and will make a bit more power usually.

[BlackThunder96]

i actually get 18 on highway goin 65-69 mph as is...I just want more of everything i guess. And for my tires to be "adjusted with everything so everything will run right". I guess i'l go with a nelson tune. My friend has one and he said once he gets something new (engine mods, increased tires, etc) he said they'll ship another??.
Call me a Dumba** but...
Im on nelsonperformance.com now, how the h*** do i order one? Call i guess?...

[GreaseDog]

i actually was looking at tunes, which ones would you go for? And my piping is 2.5" and my glasspacks are 9" long...
that 2.5" pipe is where all of your torque went. should've gone 2 1/4"

[2500ak]

You could just get a higher stall torque converter, to bypass the low end.

[cancritter]

single 3 inch will give ya your torque back...bin der done dat...aint enough power in that truck to warrent duals

[cttandy]

stick cats on it and and do something to balance the back pressure between pipes, an x-pipe or a dual in/dual out muffler. You will get a better sound, and get your bottom end torque back. I have seen to many locals do that around here, then wanna race me. Guess what, you gonna loose, and you gonna loose to the slowest 4cyl in town, in the locals case not necesarrily yours.

A fuel injected stock engine doesnt respond well to having that much back preasure taken from it.

[BlackThunder96]

yeah im putting hi-flow thunderbolt cats on and probably doing a tune or programmer.

[hotbread597]

its not backpressure that you want, its proper exhaust velocity.

[BlackThunder96]

both of them has to do with torque though...

[GMC Era]

Actually you don't want back pressure but you don't want it too free either, because either way you lose velocity. The perfect balance would be to be free flowing enough to eliminate BP but still keep the air flowing as straight as you can.
As stated by someone earlier, a single 3" does this well for most trucks' V8 engines.
If you really want "true duals" go with 2" pipes and an H pipe as close to the headers/manifolds as possible.

H pipes will yield a little more low end torque than an X pipe will. X pipes build more high end torque.

[cttandy]

its not backpressure that you want, its proper exhaust velocity.

UMmm, OK, lets break this one down. I will try to be nice cause I don't want an arguement started here.

velocity - speed of which something moves..............

exhaust velocity - speed of which the exhuast gas passes through a exhuast system, or pressure there in

back pressure - the effect of velocity of exhaust gas being passed through the exhuast system

This is kinda like me saying that a person jumped off a sky scraper and fell to the ground, and you came right back and said, NO he tumbled as a result of the gravitational pull of the earth to the ground. EEEEEEeeee, same thing, mine was just more direct as to the real issue at hand.

There is a fine line with back pressure of an engine, not to much not to little. A stock fuel injected engine needs some, just not tons.

[BlackThunder96]

yeah i kinda figured that..., cats, headers, programmer/tune, flex-a-lite fan, and cold air intake should help. which are my upcoming parts for my truck...

[cttandy]

yeah i kinda figured that..., cats, headers, programmer/tune, flex-a-lite fan, and cold air intake should help. which are my upcoming parts for my truck...

Mister Sir, I think we might have a winner here.

[Koots]

its not backpressure that you want, its proper exhaust velocity.

Thank You! It seems i have to be the one to spell that out anytime an exhaust thread pops up. quite a bit of people understand the concept but not the terminology. back pressure robs you of power.

[Koots]

UMmm, OK, lets break this one down. I will try to be nice cause I don't want an arguement started here.

velocity - speed of which something moves..............

exhaust velocity - speed of which the exhuast gas passes through a exhuast system, or pressure there in

back pressure - the effect of velocity of exhaust gas being passed through the exhuast system

This is kinda like me saying that a person jumped off a sky scraper and fell to the ground, and you came right back and said, NO he tumbled as a result of the gravitational pull of the earth to the ground. EEEEEEeeee, same thing, mine was just more direct as to the real issue at hand.

There is a fine line with back pressure of an engine, not to much not to little. A stock fuel injected engine needs some, just not tons.

You understand the concept completely but your perpetuating this automotive myth. back pressure is a bad thing for any engine any situation. if back pressure was all that he was missing than why not just stick a potato in his tailpipe to get some back. Back pressure is flow of gas or fluid reverting back onto itself, therby causing turbulence. which will hinder it's flow path. with moderate back pressure you lose the low pressure area travelling behind the spent exhaust gases which helps "suck" in the incoming charge of air. which is the scavenging effect. this is why camshafts are built with some intake/exhaust valve overlap to capitalize on this phenomenon. without it your engine isnt as volumetrically efficient and power suffers because of it.

the ideal exhaust setup for his truck would be long tube headers, with 2"-2.25" colectors (primary and secondary pipe diameters in accordance as well) running to 2"-2.25" piping and nice free-flowing mufflers. Even better on would be a H-pipe which would even out the variances between each bank of cylinders exhaust pulses or waves and broaden the torque band out quite well.

Having such large dual exhaust's diameters is crossing the boundary on flow/velocity. big pipes flow a lot more gas, but slow down the velocity. small pipes yield high velocities, yet limit flow. without a carefully matched exhaust setup for each application you will not be making efficient power. It's just the way it is.

[Koots]

Oh i forgot to mention this fascination with saying fuel injected engines need more back pressure than carb engines. I do not understand where this is coming from. someone please enlighten me :aniteef:

[cttandy]

Oh i forgot to mention this fascination with saying fuel injected engines need more back pressure than carb engines. I do not understand where this is coming from. someone please enlighten me :aniteef:


Everything I have ever read, every person I have ever talked to, has said a certain amount of back pressure was needed to get the rear oxygen sensor to pickup and read correctly. Thats, why I said STOCK engines. Now, I know of more then one vehicle, no cats, no mufflers, and 02 eliminators, that seem to have no issues what so ever.

Now, this could all be fraudlent information, just cause it was printed, and someone said it, doesn't mean its true. Just seems the vehicles I have seen have always supported that.

PS- this isn't an arguement - explain this to me please, inform me why does this seems to work

[Koots]

Everything I have ever read, every person I have ever talked to, has said a certain amount of back pressure was needed to get the rear oxygen sensor to pickup and read correctly. Thats, why I said STOCK engines. Now, I know of more then one vehicle, no cats, no mufflers, and 02 eliminators, that seem to have no issues what so ever.

Now, this could all be fraudlent information, just cause it was printed, and someone said it, doesn't mean its true. Just seems the vehicles I have seen have always supported that.

PS- this isn't an arguement - explain this to me please, inform me why does this seems to work

The rear o2 sensor, i'm guessing is the after cat HO2 sensor? in that case, it runs right after the cat, which could be viewed as a backpressure causing. Now if you were to eliminate your cats the sensor would be reading too high of levels and setting off a CEL. This might be the reasoning you have heard before, but i'm not entirely sure just going from what i can understand.

Now i'm not trying to start an argument at all. But i've seen this topic come up alot in my few years here and on other forums and i feel the need to give people the correct information whenever needed. you understand the theory behind exhaust gas velocity but chose to use the term backpressure to explain it. which is all fine and dandy, but the average joe is gonna listen to you and think that back pressure is what gives him low end torque.

It's misleading those who aren't yet schooled in automotive theory and principles. It's not me calling you out, but rather relaying what i know to those who may not and who are reading this thread right now. I say it's a service, but who am i too judge my own work? :aniteef:

[BlackThunder96]

Anyway, lol, so yeah LONG TUBE headers, hi-flow cats, programmer/tune, cold air intake, and a flex-a-lite fan should o the trick. Now i gotta question..., what to do first out of all of them.

[Koots]

Anyway, lol, so yeah LONG TUBE headers, hi-flow cats, programmer/tune, cold air intake, and a flex-a-lite fan should o the trick. Now i gotta question..., what to do first out of all of them.

Get the headers and cat first. than the tune afterwards. because the new headers will change how tuning. so upgrade first, tune later. the fans can be added whenever as it doesn't effect air/fuel, ignition or exhaust tuning at all. it just lets the engine operate under less of a load.

[cttandy]

Get the headers and cat first. than the tune afterwards. because the new headers will change how tuning. so upgrade first, tune later. the fans can be added whenever as it doesn't effect air/fuel, ignition or exhaust tuning at all. it just lets the engine operate under less of a load.


x2

putting the ducks in a row, will cost less in the end

[cttandy]

The rear o2 sensor, i'm guessing is the after cat HO2 sensor? in that case, it runs right after the cat, which could be viewed as a backpressure causing. Now if you were to eliminate your cats the sensor would be reading too high of levels and setting off a CEL. This might be the reasoning you have heard before, but i'm not entirely sure just going from what i can understand.

Now i'm not trying to start an argument at all. But i've seen this topic come up alot in my few years here and on other forums and i feel the need to give people the correct information whenever needed. you understand the theory behind exhaust gas velocity but chose to use the term backpressure to explain it. which is all fine and dandy, but the average joe is gonna listen to you and think that back pressure is what gives him low end torque.

It's misleading those who aren't yet schooled in automotive theory and principles. It's not me calling you out, but rather relaying what i know to those who may not and who are reading this thread right now. I say it's a service, but who am i too judge my own work? :aniteef:

My brain works very differently then most people. I can know an end result without the why behind it, with out caring. For instance, english I had high marks(98 average through highschool) , I knew how, didn't care why. Geometry, I knew how, didn't care why, 98 average again. I can read something about a modification, know the how, the reason for doing the modification, but not always the why it works. Now most things, I know why it does this, and how it works, and why it works. That is part of diagnosing the problems effeciently. I have no concept of a cars a/c, I have tried dearly, read books, had people show me the works, but nothing, no good to me. I know all the components, how to make them work, but dunno why it works. For this reason, I don't work on a vehicles a/c, other then just installing a new obvious part needed.

This has been what has eluded me about the fuel injected back pressure thing. I have known for many years that how to make it work, and all the parts associated, but dunno why it works that way. When I have told locals to put their cats back on and it would fix the problem, they would ask why. I just said dunno, just will, it was made that way. I knew it had to have something to do with the flow over the O2 sensor but that was about it.

I was once told it has to do with the O2 ability to heat up to a proper temperature. Never have found anythign to comfirm this though.

[BlackThunder96]

ok, thanks for you guys input on what do to first. Where do any of you think would be a good affordable site to get GOOD headers? I was lookin at long tube hedmans or something...
www.performancecenter.com (http://www.performancecenter.com) looks like they have good stuff at low prices...

[BlackThunder96]

Was also lookin' at jegs or summit.

[cttandy]

I have never heard much positive out of hedmans. I have always heard about them leaking and causing problems. I have heard alot of good about edelbrock, but I don't think they are available in a long tube.

[Koots]

There are a few guys on here running Hedman headers and haven't had a problem with them. Most headers suffer from leaking issues, but there are measures to take against such an event.

[GreaseDog]

Most headers suffer from leaking issues, but there are measures to take against such an event.
:word: exhaust manifold gaskets (NOT header gaskets) and aluminum or copper collector gaskets.

[mrbray101]

I think when you put the cats on there you will be fine. My truck didn't seem to lose any low end when I went true dual bullets w/ high flow cats.