BlutVonSchwachen

iTrader: (7)

I just started classes at Denver Automotive and Diesel about 5 weeks ago. A classmate and I are having an arguement over my car. So we agreed to post it here and get a final say to see who is right, which is me of course but he doesnt want me putting on who thinks what just to make sure the answers given arent one sided or something like that. So here we go:

Car: 1998 Chevy Camaro Z28 (LS1, 6spd)

Plans: Swapping stock manifolds and exhaust for Pacesetter race style LT headers and TSP Rumbler X (TD) exhaust.

Tech A Claims: The car will need to be tuned to even out the Air/fuel ratio after the installion of the LT headers. During the tune, the car may also be put on the dyno to get the HP/Torque rating. Also suggests seeing if the idle may be adjusted to a lower setting (currently runs at 1krpms during regular operating tempartures).

Tech B Claims: The car does not need tuned just because LT headers. Tune will not be needed to adjust the idle.

So, who is correct in this situation and on what part are they right on? (I got $5 riding on that I am right, so the sooner you reply the sooner I get to earn some molla.)

spy2520

iTrader: (3)

Well you dont have to get a tune for LTs. But i just put race style pacesetters on and i'm gonna get tuned just for optimal performance/mileage. Not a necessity, but still something i wanna do.

Time2Kill

iTrader: (49)

Sure, you can just throw on LTs and a new exhaust and not get a tune. Will you get the best performance from them? NO! More than likely you will be running rich, and if its anything like when I first did LTs on my car, it will be shooting flames out the exhaust bc its running so rich.

So do you need a tune, no, but then again you won't be getting all the performance out of your new setup either.

RPM WS6

iTrader: (3)

No tuning is required for headers/exhaust, but it will improve performance.

As for the idle, unless the car is having issues or someone already raised it (either with tuning, turning the set screw, propping open the blade, etc.) your idle is not 1000rpm. A '98 M6 LS1 is set to idle at 800rpm once warm. If you're just going by the tach then try scanning it to get the true idle speed.

No need to drop the idle lower, no point really.

Danny2tek

iTrader: (1)

Each engine responds different to mods.

LSONE

iTrader: (1)

I didn't tune my car once I put my pacesetters and TSP duals on, but it ran rich as hell too. I would say that you can run without a tune, but your a/f will be off, and if you're idle is at 1000 it's way too high

bichin95redta

Tech A is correct. You'll need to add fuel and timing advance to take full advantage of the increased exhaust flow. Engine management systems have many parameters, each with their own look-up tables. Some of the parameters even change over time in order to compensate for changes in the performance of engine components like catalytic converters. Installing long tube headers is usually done in one of two ways: off-road (no cats) y-pipe, or catted (usually hi-flow, aftermarket cats from companies like Magnaflow, or Random Technologies) y-pipes. Either way, exhaust flow values will no longer look like the OEM values. Generally, the more aggressive your set up is, the more critical the PCM tune.

RPM WS6

iTrader: (3)

I don't think that Tech A is actually 100% correct. Here's why:

Need is the key word. If "need" was meant to mean "required", then the statement is wrong. Granted, the motor will almost certainly benifit from a tune, but it's not required.

Now, as for Tech B stating:

This is actually 100% correct, again assuming that "need" means "requires", as the car will not require a tune just for the exhaust change, though it will likely benifit from one.

What it really comes down to is, are Tech A and B in disagreement over the car benifiting from a tune or actually needing a tune? That is what makes the difference over who is right and who is wrong. Actually, A and B might both be correct, depending on what they each mean by "need".

rufretic

iTrader: (37)

Good answer. I agree, both arguments are correct. Tech A "The car will need to be tuned to even out the Air/fuel ratio" this is true but Tech B is also correct, the car doesn't NEED a tune to run with long tubes. It does however need a tune to get the full gains from the LTs.

cyphur

iTrader: (10)

The addition of long tube headers does not neccessitate a PCM tune, however a PCM tune after the addition of long tube headers would help.

I think Tech B is more correct(at least in wording) than Tech A, especially concerning the idle. Only reason your idle will change when you swap headers is when you messed up bad.

I tuned my car after adding headers, however, with HP Tuners, fwiw.

jdaniels

iTrader: (12)

The statement of Tech A is correct. Re-read it.

Tech A is correct, despite the ECU's learning capabilities, as explained above by another the exhaust flow is radically different. The ECU does not know 100% how to correctly respond to it, thus the NEED for tuning "to even out the Air/fuel ratio after the installation of the LT headers" the statement says its NEEDED to even out the A/F ratio, this portion is true. Even though tuning isn't required for the car to RUN, it is the only way to even out the A/F's to where they should be for the given exhaust flow.

bmfcamaro

iTrader: (1)

as a fellow 98 owner the tachs are 150-200rpms high so your idle sounds right. another special 98 thing. hehe!

GuitsBoy

iTrader: (4)

Both have valid claims, but neither is 100% correct.

The computer will compensate for the mods both in terms of fueling (LTFTs) and idle (LTIT). However, particularly the fuel trims will not be completely accurate since they have to blanket a large part of the VE table. A proper tune will get the VE table in line and the trims will be closer to 0, making correct fueling much more accurate.

OTOH, The reason why you cant just say that a tune is mandatory is because while you stand to gain a lot from a tune with these new mods, A tune will even help out a perfectly stock car. These cars are tuned very conservitively (rich) from the factory.

If you have the means to tune the car, theres no reason why you shouldnt. However If youre wondering if you can get by without tuning but still see gains, then consider a tune unnecessary at this point.

Once you get into changing internals or injectors or any other metered flow equipment, the tune will be required.

A 2000 SS in Jersey

iTrader: (4)

Do you need a tune..........No

Do you want a Tune..........Hell yes.......