Tune or no tune?

**SS-Power** · 02-09-2008, 09:35 AM

I'm getting long tube headers, catback, and my tb ported and polished.
Should I get a tune with these mods? I'll probably won't do any more modding for awhile.

**00z28bubba** · 02-09-2008, 10:51 AM

the headers are going to throw off your air/fuel ratio which is never good so if u got the money pick it up. tuning after i got my LTs made the car a completely different beast. i drove it about a month before getting the tune. it seemed like it was gonna fall apart now its smooth and strong in every aspect from braking to idling the highway driving and gas mileage.

**SS-Power** · 02-09-2008, 10:58 AM

Originally Posted by 00z28bubba

the headers are going to throw off your air/fuel ratio which is never good so if u got the money pick it up. tuning after i got my LTs made the car a completely different beast. i drove it about a month before getting the tune. it seemed like it was gonna fall apart now its smooth and strong in every aspect from braking to idling the highway driving and gas mileage.

Makes sense, then I'll get a tune. What numbers did you put down?

**shady milkman** · 02-09-2008, 11:40 AM

Originally Posted by 00z28bubba

the headers are going to throw off your air/fuel ratio which is never good so if u got the money pick it up. tuning after i got my LTs made the car a completely different beast. i drove it about a month before getting the tune. it seemed like it was gonna fall apart now its smooth and strong in every aspect from braking to idling the highway driving and gas mileage.

x2 a tune is a must to matc up the a/f ratio

**SS-Power** · 02-09-2008, 11:42 AM

Originally Posted by shady milkman

x2 a tune is a must to matc up the a/f ratio

Do you think I have enough air coming in for my setup?

**shady milkman** · 02-09-2008, 11:48 AM

Originally Posted by SS-Power

Do you think I have enough air coming in for my setup?

yea for your set up deff. when you start needing more air is when you add h/c or power adders ect....even just a cam or just heads will ussually be pushing stock ls1 intake manifold ...plus its a good idea to upgrade to a ls6 intake manifold..and save the fast 90/90 for later down the road when you are running some serious time mods..but for your set up now you are fine. but look into a ls6 intake manifold

**SS-Power** · 02-09-2008, 11:50 AM

Originally Posted by shady milkman

yea for your set up deff. when you start needing more air is when you add h/c or power adders ect....even just a cam or just heads will ussually be pushing stock ls1 intake manifold ...plus its a good idea to upgrade to a ls6 intake manifold..and save the fast 90/90 for later down the road when you are running some serious time mods..but for your set up now you are fine. but look into a ls6 intake manifold

ok, thanks

**00z28bubba** · 02-10-2008, 12:16 PM

mine were 306hp and 323 tq to the wheels but i didnt have any air no free ram air at the time. do that first and make sure they get air to your lid. not sure how much that would have helped. but i would assume it would help more

**shady milkman** · 02-10-2008, 04:24 PM

Originally Posted by 00z28bubba

mine were 306hp and 323 tq to the wheels but i didnt have any air no free ram air at the time. do that first and make sure they get air to your lid. not sure how much that would have helped. but i would assume it would help more

you can always use more. but however he is not starving his system. the ls1 manifold is not pushed to its limits..not even close with the numbers/ mods he has

**00z28bubba** · 02-10-2008, 04:34 PM

when i did the dyno tune the fan they had set up was aimed straight at the grille of my car which is completely blocked off from the styrofoam bumper filler. which to me seemed like my car wasnt getting hardly any air as it would be just driving around as opposed to on the dyno. but like i said i just did the free ram air mod so im again not sure if it would have helped by moving the fan anywhere else except above the bumper aimed directly at the lid. thinking about it now just seems like i could have had more air than aiming the fan at practically a wall

**Frost** · 02-11-2008, 06:15 AM

Originally Posted by shady milkman

you can always use more. but however he is not starving his system. the ls1 manifold is not pushed to its limits..not even close with the numbers/ mods he has

I don't know what you mean by it being "pushed to it's limits" but I've never seen an LS6 intake go onto a car that had an LS1 intake and not make power. They make power on stock cars.

**Spaz** · 02-11-2008, 06:54 AM

Originally Posted by 00z28bubba

the headers are going to throw off your air/fuel ratio which is never good so if u got the money pick it up. tuning after i got my LTs made the car a completely different beast. i drove it about a month before getting the tune. it seemed like it was gonna fall apart now its smooth and strong in every aspect from braking to idling the highway driving and gas mileage.

sounds like you had a sensor issue or something... headers don't throw off air fuel very much...

**Frost** · 02-11-2008, 07:14 AM

Originally Posted by Spaz

sounds like you had a sensor issue or something... headers don't throw off air fuel very much...

They do to an extent; a car will get much more out of tuning post headers than pre-headers, often times 15-18rwhp and sometimes more. They are prone to making O2s lazy down low from heat loss as well though there is often little that can be doen in the PCM to correct this. In the autos, raising the idle helps. I have no idea why the factory commands a 550rpm in-gear idle for autos anyway, the car is much happier idling at 650-700.

**Spaz** · 02-11-2008, 07:59 AM

Originally Posted by Frost

They do to an extent; a car will get much more out of tuning post headers than pre-headers, often times 15-18rwhp and sometimes more. They are prone to making O2s lazy down low from heat loss as well though there is often little that can be doen in the PCM to correct this. In the autos, raising the idle helps. I have no idea why the factory commands a 550rpm in-gear idle for autos anyway, the car is much happier idling at 650-700.

agreed... but i doubt they would throw off the AF ratio enough to make the car feel like it has less power than the stock exhaust manifolds provided... and the 550... leave it to gm to make no sense...

**shady milkman** · 02-11-2008, 11:11 AM

Originally Posted by Frost

I don't know what you mean by it being "pushed to it's limits" but I've never seen an LS6 intake go onto a car that had an LS1 intake and not make power. They make power on stock cars.

well yea no kidding. But what i was saying is that his system wasnt starving for air. of course it could use more but it would not be starving by any means..now if he was running the ls1 intake and had a radical h/c and a power adder then ya as we all know the system would be starving for air since the ls1 intake couldnt supply enough..sorry if i was unclear.