Just got my car back from the Dyno.
Car only made 326 to the wheels with the following mods

06 convertible ls2
Vararam CAI
Kooks 1 7/8 headers & Catted X-pipe
Corsa axle back (not sure what model)
Tune

Do the numbers seem low? I guess I was expecting more.

 

My 05 dynoed 330 when new.

 

A Mustang dyno reads about 10% lower than a dynojet. So you're around 365 on a dynojet. considering a 15% drivetrain loss, you're around 420 at the crank. right about where you should be.

 

I seriously doubt 365 on any dyno.

 

Don't truth the read out, since its showing AFR at 9.
Hence should be 12.5~12.9AFR at WOT on a N/A motor to make the most power isntead.

If S/C motor, then around 11.5~12 instead.

Hence at 9, tail pipe should be throwing huge smoke with it running way, way too rich.

Torque and HP cross over looks about right, but did not play with AFR and spark advance to keep it from going flat at 5.9 k instead.

Hence should look something like this if tuned correctly on all stock LS2.
Note, MX6 and why more at the wheels than a A6 trans car. and if you add long tube header to the below, will increase the HP and torque about another 25hp (since its the only item that you added that will increase HP in your line up of add on parts)..
Attachment 48339858

 

Also, don't trust that the widebands were even working. 9.0 EXACTLY for the ENTIRE RUN? (9.0 max, 9.0 min). Something seems off about that. I'm thinking that it wasn't reading AFR.

 

How in the hell do you tune without knowing AFR readings to start with?

 

So if I were to take it back to get re-tuned what exactly am I looking for?

 

This is from my first C6 for reference, mods are a little different. Blue is before cam swap, red is after.
Before cam mods were Hinson 1 7/8 headers, Vararam CAI, Borla Atak Catback. Made 377 whp / 390 wtq untuned.
Cam was a BTR Stage IV N/A Cam. After cam install and tune car made 433 whp / 409 wtq.

 

Before you have them do anything else, I would ask: When they tuned it last, did they measure AFR (air-fuel-ratio)? Do they still have those readings? Can they print them off or show them to you?

Then compare that to what Dano523 said "should be 12.5 ~ 12.9 AFR at WOT on a N/A motor"

 

This was on a Dynojet which typically reads higher than a Mustang Dyno. It's also worth noting that this was a few years ago in October, ambient temperature was around 70 degrees which makes a big impact as well.

 

First off, if this is a LS-2, the low down for starters is your trying to hold the AFR to 12.9 for WOT, since that is where the motor is going to make most of is power.
Also, your working with timing advance as well, so nice to see that on the graph too. Hence you don't want to push the timing at any point too much, or your going to run into detonation problems and the motor is going to retard timing on it own.

Next is going to be the motor nose diving in HP around 5.8rpms with holding AFT at 12.9 past 5.8K rpms. So here is where you need to lean out the AFR, and work with more timing advance so the HP is still climbing to bounce off the rev limiter hard, isntead of the motor wanting you to shift at 5.9 isntead. If an auto, trans get tuned, and we want to set the trans to shift about 5.9, so it will be in the next gear before the motor does bounces off the rev limiter. Hence if the motor is going flat at 5.9 like in your case, then you would have to set the trans shift point to about 5.6 so it in the next gear before the motor goes flat.

As for ase smoothing something like 5 ideal, and you don't want to smooth to 20 instead.

The last item on the block, since you do have long tube headers in place, we need to see where the motor comes on the pipe (headers starting to scavenge there best). On your dyno, I can see the headers coming on the pipe at 3.4K and this screaming that your Running headers of 1-7/8" or larger ID, or the high flow cats where placed too close to the collectors of the headers and why they are coming on the pipe so late in the RPMs instead.

Hence headers work by scavenging the exhaust gases out of the other pipes that the cylinder is not firing, allow for more exhaust to be pulled out of the heads/cylinder. If the volume of the pipe is too large, or the design of the pipes too long, then it take much more exhaust pressure/higher RPMs before they start to work effectively.

Watch these to understand how header work, and why larger ID/long pipes help to make more HP up on the top end, but you can end up losing power on the bottom end isntead. So the ideal header will come on line at idle, and will not wash before max RPMS are acheived isntead.



So to sum it up, if you just going somewhere to do a dyno pull, make sure that AFR sensors are hooked up, and you get both AFR and timing advances on the Dyno print out. This will explain what is going on and why on the graph charts, and if the problem is the AFR/timing, or you have other problems isntead.

 

I think the pipe dia. for the headers is to large. 1 3/4 would of better better for LS2 motor with basically no mods.

Torque numbers are too low.

 

Hard to say with out knowing the ID of the header pipe, distance of the high flow cats after the collector, and the tune as well.

Dip is pretty hard from 3K to 3.4K from the initial climb, and could be all in the tune.

 

Dano 523 your knowledge far exceeds mine without doubt, just my experience with headers on a few different cars.

 

x2 on getting the tune rechecked. at 9.something its a wonder its even running that would be crazy rich. Not sure I buy it?

 

I don't put much faith in just pure dyno numbers, since the real test is how well the car actually moves. It's a tuning tool to get you close to the point where the car performs the best, but there's always more if you know where/how to find it.
My first dyno pull netted 306 hp (Mustang). After a tune it got up to 320 and my 1/4 mile times dropped by .20. I added a CAI and dropped another .20. Then the tuner came to the track and tweaked the tune according to a 1/4 mi pass scan and I instantly dropped off another .15
Now I run high 10's and the latest dyno sheet only shows 394 hp on a Dynojet. Lots of guys with 430+ dyno sheets are still in the mid-11's.
How the cars runs is far more important than dyno numbers.

 

Agreed, use of a dyno just makes getting the tune close faster, but until you put the actual cars load on the motor under real conditions, then you can't final the tune.

So even with a road drive test after you dyno tune to double check the tune, your still only going to be close, unless that final road test is on the track under real conditions isntead.

Hence for road coarse work, you can run the motor on the leaner side to really crank out the max HP, but fuel is cooling, and in some cases, you may richen up the tune to keep the motor from over heating with the a small loss of HP that may come with such initial number isntead. Hence motor gets too hot, and it will pull timing, so may end up with less HP in the end when the motor is running too hot on the lean side run longer, over running the motor a little richer so it holds it HP for the entire session isntead.