[Fraxum]

Originally Posted by cmitchell17

The engine will run fine and normally at a stoichiometric ~14.1:1 air fuel ratio at WOT. Enrichment is done at high throttle and WOT because of the extra cooling offered by the extra fuel, and to make more power than could be made at stoich ratio.

By running slightly richer (up to a point) you will give it a little extra fuel to ensure that all the available oxygen is "used up" or burned. Perfect combustion (or in chemistry terms a completed reaction) is always pursed but usually never reached (eventually it is reached in the cat converter).

Thanks! I don't want my rambings mis-informing others. While I want to learn I will leave tuning to those who paid the price to get there.

I know a ton about software integration. Tuning to me is still a black art.

I will leave it to the experts.

[OB0001]

Originally Posted by Chemist

I ordered the LT2 from GPI on 8/21 and received it yesterday. Don't worry about them, you will receive it

Thanks Not worried just glad the IM LT2 are in stock

[m6-lt1]

I’ve been asking a lot about this subject as well and have seen people say they ran a little lean at wot or say their afr remained steady. I don’t know very much about tuning I will admit, but I am starting to wonder if the people who saw their car go lean immediately looked at afr before driving the car around a bit and letting the ecm do its self calibrations. The reason I am thinking this is because i remember talking to one guy who’s car didn’t run properly after the install (Forgot to disconnect battery before install) but after a few miles it went back to running normal.

[squish72]

Originally Posted by m6-lt1

I’ve been asking a lot about this subject as well and have seen people say they ran a little lean at wot or say their afr remained steady. I don’t know very much about tuning I will admit, but I am starting to wonder if the people who saw their car go lean immediately looked at afr before driving the car around a bit and letting the ecm do its self calibrations. The reason I am thinking this is because i remember talking to one guy who’s car didn’t run properly after the install (Forgot to disconnect battery before install) but after a few miles it went back to running normal.

Just wanted to mention something about the self calibrations comment. The ecm has basically set values and uses the o2 sensors to fine-tune (adding or reducing fuel). The numbers never actually change, the o2s just add or reduce fuel as it seems needed on the fly. If it is constantly lean or rich the o2s have what's called a long term fuel trim where it will store a bit of data saying it always this or that so we will start with adding or reducing this much to begin with. Pulling the battery can clear that long term trim, kinda starting back from scratch.

The kicker is our o2 sensors are narrow band, meaning they are only built to look in a small range of data. If youre outside of that range it might try and add fuel or lean things out when you don't want it to. That's why it's important to have a wide band sensor so you know what things are doing. Cause it may be rich in most of the rpm range but have a lean spike that the computer can't see and just continues to lean the set tune out.

One last thing. The tune usually switches to the maf sensor after a certain rpm and doesn't use the o2 sensors. So if that's off you may be fine driving around town with the o2 sensors doing their job but once you get on the gas what ever is set into the tune is what your going to get.

[s346k]

Originally Posted by Fraxum

Thanks! I don't want my rambings mis-informing others. While I want to learn I will leave tuning to those who paid the price to get there.

if you have a wideband and hpt you can always install the manifold and record your findings and save the logs. the intake manifolds only take about 20 minutes to swap out. maybe 30 if you've never done it before.

just be sure to get plenty of logs on the stock intake manifold beforehand.

[Mountain]

Originally Posted by cmitchell17

I have to disagree with everyone, the MAF sensor will pick up the additional airflow at higher rpms, especially since the ECM ignores everything except the MAF sensor above 4000 rpms.

Yeah, this is where im at with thinking.

The LT2 intake TB opening doesn't seem to be all that different than the LT1 intake. The big thing with the LT2 intake is equalizing the runners and increasing the plenum volume. This allows easier flow into the runners (plenum) and equalizes flow through each of the runners (runner dimensions); it will also augments the strength of resonance tuning (plenum). The runner cross-section should be the same (per GM) and the runner lengths for the LT2 are roughly within what the LT1 is (per GM).

So, you are changing the efficiency of air into the engine between the intake tract system (TB, intake tube, MAF housing, airbox) and heads (intake port, intake valve and chamber). You can only pull so much air from the 87mm TB+stock intake tube and expel so much/pull in so much air through the factory exhaust on the factory cam.

The questions are: 1. At what capacity did GM accommodate, in their factory tune, of the 87mm TB and factory intake tract/tube in the Camaro? Someone out there should already know this by now from tuning these engines. We know it's not 100% through people changing to an MSD intake or larger TB only and their data logs. 2. Is the flow potential between LT1 and LT2 intakes enough to push outside the factory MAF calibration? This is something else we should be getting to know now. We know the MSD can max out the factory MAF calibration by around 5,500RPM and we know (per GM) the LT2 intake can flow 4% more than the LT1 intake. The MSD has a larger, bell-mouthed TB opening, shorter, larger runners with a similar plenum to the LT1. It seems ported LT1 intakes flow somewhere close to 4% better than factory and there are plenty of people running ported LT1 intakes without a tune.

GPI has stated they don't believe a tune is needed. We shall see

[TJay74]

Originally Posted by cmitchell17

I have to disagree with everyone, the MAF sensor will pick up the additional airflow at higher rpms, especially since the ECM ignores everything except the MAF sensor above 4000 rpms.

While correct in how the MAF picks up, 4k RPM's isnt a set in stone point as it depends on where PE (power enrichment) is set to come online at. The MAF scale though does rely on the EQ Ratio to determine the commanded A/F and then uses the airflow data the MAF gives it to determine what EQ Ratio to use.

[Nabush]

Originally Posted by TJay74

While correct in how the MAF picks up, 4k RPM's isnt a set in stone point as it depends on where PE (power enrichment) is set to come online at. The MAF scale though does rely on the EQ Ratio to determine the commanded A/F and then uses the airflow data the MAF gives it to determine what EQ Ratio to use.

You won't likely need a tune for an IM. Like said before the MAF will pick up additional airflow. Variable airflow (mix of VE and MAF) is used until 4000 rpm. Then it is MAF only.

MAF value will be used to calculate amount of fuel to reach the commanded EQ ratio. PE or not. PE is just additional enrichment on top of normal ratio. (Around 1.13-1.19, so 13-19% more fuel).

If MAF sees more air it adds more fuel plain and simple.

Ideally the best is to have a wideband to be 100% sure but IHMO it is safe.

[squish72]

If your doing just the intake I wouldn't worry. If you already have other mods like a cai it's better to be safe then sorry.

[vtirocz]

Originally Posted by Mountain

Yeah, this is where im at with thinking.

The LT2 intake TB opening doesn't seem to be all that different than the LT1 intake. The big thing with the LT2 intake is equalizing the runners and increasing the plenum volume. This allows easier flow into the runners (plenum) and equalizes flow through each of the runners (runner dimensions); it will also augments the strength of resonance tuning (plenum). The runner cross-section should be the same (per GM) and the runner lengths for the LT2 are roughly within what the LT1 is (per GM).

So, you are changing the efficiency of air into the engine between the intake tract system (TB, intake tube, MAF housing, airbox) and heads (intake port, intake valve and chamber). You can only pull so much air from the 87mm TB+stock intake tube and expel so much/pull in so much air through the factory exhaust on the factory cam.

The questions are: 1. At what capacity did GM accommodate, in their factory tune, of the 87mm TB and factory intake tract/tube in the Camaro? Someone out there should already know this by now from tuning these engines. We know it's not 100% through people changing to an MSD intake or larger TB only and their data logs. 2. Is the flow potential between LT1 and LT2 intakes enough to push outside the factory MAF calibration? This is something else we should be getting to know now. We know the MSD can max out the factory MAF calibration by around 5,500RPM and we know (per GM) the LT2 intake can flow 4% more than the LT1 intake. The MSD has a larger, bell-mouthed TB opening, shorter, larger runners with a similar plenum to the LT1. It seems ported LT1 intakes flow somewhere close to 4% better than factory and there are plenty of people running ported LT1 intakes without a tune.

GPI has stated they don't believe a tune is needed. We shall see

All good points. Thanks for sharing that!

One thing that's interesting is the worse flow at ~3600RPM and subsequent (~13 lb-ft drop there) with the LT2 manifold.

[Fraxum]

Reply to myself....

"I have one on order. I am a bit peeved GPI took my Paypal $$ with no delivery date to ship. But I might as well buy it anyway, it will be easy to sell if I do not use it."

In the discussion I was a little peeved about this But not worried about GPI. Now I want to shout out GPI for how well thet treat thier customers.

First they are really on top of shipping and delivery notifications. When I received my LT2 IM it was shipped without the map extension. I was bummed as I was planning to do the install this weekend.

But after I called them they shipped me the extension overnight! My weekend covid plans are saved!

Now I have the LT2 IM to install and I also now I have a C8 cover. In addition this weekend I plan to pull the bumper cover off to better fit my Velossa Tech scoop. I like that it just helps IATs and not really the airflow. The LT2 already runs a touch lean up top.

With good Atco air I hope for 11s on a stock tune, seats in. Given that I want to kee p my LT1 for my forever I am putting off a tune for now.

Especially if Atco closes. :(

[OB0001]

Originally Posted by Fraxum

Reply to myself....

"I have one on order. I am a bit peeved GPI took my Paypal $$ with no delivery date to ship. But I might as well buy it anyway, it will be easy to sell if I do not use it."

In the discussion I was a little peeved about this But not worried about GPI. Now I want to shout out GPI for how well thet treat thier customers.

First they are really on top of shipping and delivery notifications. When I received my LT2 IM it was shipped without the map extension. I was bummed as I was planning to do the install this weekend.

But after I called them they shipped me the extension overnight! My weekend covid plans are saved!

Now I have the LT2 IM to install and I also now I have a C8 cover. In addition this weekend I plan to pull the bumper cover off to better fit my Velossa Tech scoop. I like that it just helps IATs and not really the airflow. The LT2 already runs a touch lean up top.

With good Atco air I hope for 11s on a stock tune, seats in. Given that I want to kee p my LT1 for my forever I am putting off a tune for now.

Especially if Atco closes. :(

I would also recommend GPI

[lt4camaro]

Originally Posted by Fraxum

Thanks, what is that number, gas/oxygen ratio or some thing like that? We are taliking about AFR?

I also found this:

"For example, for a gasoline engine, an AFR of 16.5:1 is lean and 13.7:1 is rich."


And the optimal AFR:

"The stoichiometric mixture for a gasoline engine is the ideal ratio of air to fuel that burns all fuel with no excess air. For gasoline fuel, the stoichiometric air–fuel mixture is about 14.7:1 i.e. for every one gram of fuel, 14.7 grams of air are required."

So in tuning the tuner tries to get to the stoichiometric mixture throughout the rev range? Or do they cheat a little by going slightly lean with a little more timing? Just guessing.

Wouldn't the knock cause the software controlled timing to pull back with the stock tune protecting the motor and negating the benefit somewhat of the LT2 IM? Tuners would smooth out the AFR to get the full benfit of the IM.

I only run 93.

So I have a new HP tuner brick to log my runs if I put the LT2 IM on. Then I can probably find someone who can help me figure out what is happening when I run all out.

Appleman22, thanks for the heads up. Sound like a plan?

ThE LT2 IM should get me into the 11s. I also added the VT Scoop and a Rotofab dry. With the DRs and RF I am at 12.10.. in +200 air. Seats in.

You must be driving a manual LT1 and not a 10 speed auto?

[Timbo-1LE]

I gave up. Sent a note part received and mods in work. Called two weeks.later, waiting on extention, then waiting on manifold.... After four weeks and three calls with three different reasons.

Will just wait and do it myself... And get a return. I'm sure they are good people, but lack of clarity concerns me.