[ShockSS]

Ive absolutely burned the search function up both on the site and through google but sometimes its just worth asking yourself haha. I have a 19 SS with longtubes, xpipe, axle back and e85 tuned. The tune was performed directly after all the mentioned mods were done. Im now thinking about buying a rotofab as well as an lt2 intake. The question is pretty simple, after i install will the car REQUIRE a retune? I understand the ideal situation would be yes, but is it an absolute dire must? I ask mainly because it could take me a while to get back into my tuner.

Thanks!

[FlukeSS]

LT2 intake yes, you will need a tune, and the tune will optimize the rotofab as well.

LT2 with no tune will lean out your current tune, and retune will be needed to make sure not running to lean.

Depends on your current tune settings of course, often there is room to play with the intake, I think it only changes the lean tables by a few points, and if you have enough margin below running to lean, than you might be ok, but its a risk you take if your current tune is maxed out on running lean already.

If it was just the rotofab I would have said no.

[FarmerFran]

My advice from way back has always been the same. You spent that much $ on a vehicle to modify, every change at least check the tune.

[lt4camaro]

I ran my unported LT2 intake, with a solar 91 mm TB and I modded my own factory air box for more flow and removed the snow block in behind the grille that obstructs the air intake area for two months with absolutely no issues before I had the car tuned. The ECU does adjust somewhat to the extra air flow over time and as long as you do not do to many WOT pulls, you should be fine till you get to the tuner.

[s346k]

i did almost exactly what you are doing.

ported LT1 manifold
long tubes
ethanol tune
cut stock airbox

went to a rotofab and LT2 manifold. with no tune changes the car barely leaned out, .01-.015 lambda. but the car picked up 1-1.5 mph via dragy. i had that setup on the car for a few weeks with several 60-130 pulls and lots of street miles. it is best to monitor these things yourself as every car, tune and tuner are different.

i don't think the rotofab contributed much, if any, to the gain. the stock cut airbox and rotofab testing i previously did showed no gain.

i'm a big fan of the LT2 manifold for basic bolt on cars.

edit: retune required? most likely not. but to get the most youll want it touched up and the rev limiter raised at minimum.

[adamjwilson]

Originally Posted by FlukeSS

LT2 intake yes, you will need a tune, and the tune will optimize the rotofab as well.

LT2 with no tune will lean out your current tune, and retune will be needed to make sure not running to lean.

Depends on your current tune settings of course, often there is room to play with the intake, I think it only changes the lean tables by a few points, and if you have enough margin below running to lean, than you might be ok, but its a risk you take if your current tune is maxed out on running lean already.

If it was just the rotofab I would have said no.

Yeah... what he said.... however the RotoFab (Big Gulp) does require a tune per RotoFab.

[Briland_1LE]

Originally Posted by FlukeSS

LT2 intake yes, you will need a tune, and the tune will optimize the rotofab as well.

LT2 with no tune will lean out your current tune, and retune will be needed to make sure not running to lean.

Depends on your current tune settings of course, often there is room to play with the intake, I think it only changes the lean tables by a few points, and if you have enough margin below running to lean, than you might be ok, but its a risk you take if your current tune is maxed out on running lean already.

If it was just the rotofab I would have said no.

You don't need a tune for the LT2 intake manifold. The MAF sensor is in the intake tube and is reading the flow at that point. The OEM intake can't physically flow more air into the engine than its geometry allows. If you get the Big Gulp you need a tune because now the MAF is in a larger diameter tube meaning at a given reading it is underestimating the airflow because the intake can physically flow more air now. So put the LT2 manifold on and not the intake if you don't want a tune. There is a benefit to the LT2 even though you can not flow much more air because of the runner geometry moving the power curve higher in the RPM range. Source: I'm a mechanical engineer.

[6spdhyperblue]

Originally Posted by Briland_1LE

You don't need a tune for the LT2 intake manifold. The MAF sensor is in the intake tube and is reading the flow at that point. The OEM intake can't physically flow more air into the engine than its geometry allows. If you get the Big Gulp you need a tune because now the MAF is in a larger diameter tube meaning at a given reading it is underestimating the airflow because the intake can physically flow more air now. So put the LT2 manifold on and not the intake if you don't want a tune. There is a benefit to the LT2 even though you can not flow much more air because of the runner geometry moving the power curve higher in the RPM range. Source: I'm a mechanical engineer.

While this is true in theory, the result does not prove this to be true.

I believe this is the case due to movement of the throttle body as it is higher. This clocks the tube and throws off the reading. I would tune for optimal fueling.

[Briland_1LE]

Originally Posted by 6spdhyperblue

While this is true in theory, the result does not prove this to be true.

I believe this is the case due to movement of the throttle body as it is higher. This clocks the tube and throws off the reading. I would tune for optimal fueling.

Not saying you're wrong but I don't understand what you mean when you say moving the throttle body up higher clocks the tube and throws the reading off?

[Aaron07]

Hoping to piggyback a little off this: I already have the LT2 IM and 95mm TB both GPI ported. I just don't like the look of it. I will either be getting the C8 engine cover or going with the MSD. If I go MSD, what's the consensus on needing a retune?

[KingLT1]

Anytime you change mods the tune should be checked.

[wang970305]

usually retune is cheaper with the same tuner

[REDDEVIL2SS]

WHAT IF MY CAR IS COMPLETELY STOCK

[bishopts]

Originally Posted by REDDEVIL2SS

WHAT IF MY CAR IS COMPLETELY STOCK

No need to tune a stock car. But... there is power left on the table that a tune will find on a stock car.