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Local shop had a "Dyno day" so I took it over to put it on, no tuning, just to see what it was like. They said their Dyno reads super low, 12% low. Put down 339hp/321tq. For comparison a LS3 Corvette did 345hp/339tq. With just a cat back exhaust I was really happy getting so close to the LS3. I wish I had bigger numbers but now I got a Dyno sheet to wave around
An STS-V showed up and his piggyback tune was so bad I made more power than him. He was not too happy and promptly left
Is the exhaust manifold what's holding the torque down? Thought there was something that caused the peak torque to be less than the Corvette equivalent.
The manifolds are very similar in design, but the rest of the exhaust is definitely different. Caddies had a resonator with a built-in crossover design that the Corvettes did not. The Vettes have a pretty straight section with a very short H-pipe in the equivalent stretch:
The mufflers on the Vette probably flow better too. They have a single in dual out configuration that provides a pretty good pressure drop. I don't remember what the cut open cross section of the V's stock mufflers look like, but from what we've seen in terms of power gained in muffler deletes, cat backs, and frankenstein systems like mine, there's not much to be had in muffler swaps. I think the biggest restriction found was the stock cat converters. All else the same, the guy that swapped high flow cats in place of his stock set gained a significant amount of power with a retune.
I would look at the intake tube, and cam before the exhaust. Yes the cats are restrictive, but the cam isnt lettin your heads flow And if you cant get air into the engine fast enough you wont make power...
I would look at the intake tube, and cam before the exhaust. Yes the cats are restrictive, but the cam isnt lettin your heads flow And if you cant get air into the engine fast enough you wont make power...
Good point. If he's still running the stock intake tube, that gets pretty choked.
I don't have a fully stock exhaust. It had a Billy Boat cat back already on when I bought the car. It also came with a K&N CAI but I've been procrastinating on installing it lol.
Our cars (and vettes) don't benefit much from exhaust upgrades after the cats, unless you go 3". The resonator has an X inside, the mufflers are decent, and the whole thing is 2.5" with a good design. LMR told me years ago that they never saw any power improvements on this platform or vettes, just sound improvements. Power is improved with headers, cats/off road pipes, or bigger tubes behind the cats.
I'm with Bud, you REALLY should have installed that CAI before dyno tuning. See if they'll cut you a deal on a retune.
Doh! Right there in the first post - no tuning. Nope, not a huge deal. That said, the right cold air intake gives notably more power in every case I've seen. In this case, you'll get more power from a CAI than a cat-back...no question. It's true on this car, gen5 camaros, G8s, etc. You'll struggle to find a case that says otherwise.
Ok so I dropped in the K&N intake. 20 minutes of driving in the cool evening the CEL light came on. I'm guessing it's lean codes, that's what it was when it was on initially and why I took it off. However the next day the light has went off and not came back (the weather has been 80 degrees hot in the day). I cleaned the MAF with MAF cleaner for good measure.
Ok so I dropped in the K&N intake. 20 minutes of driving in the cool evening the CEL light came on. I'm guessing it's lean codes, that's what it was when it was on initially and why I took it off. However the next day the light has went off and not came back (the weather has been 80 degrees hot in the day). I cleaned the MAF with MAF cleaner for good measure.
It probably got oil from the filter on the MAF, so cleaning it would've been the next step. Good work.
The engine light and lean codes in both banks comes on still from time to time. Is my reasoning wrong that it happens in cooler air (like at night) because the air is more dense? I think the filter element is bone dry. The K&N came with the car and had done this before so I had been using the stock intake since.
Assuming a tune would fully take care of it but I was hoping for a few more bolt ons to get the most out of spending on a tune.
from the budget perspective, I wouldn't tune it if the A/F ratio is already spot on. Looking at the dyno posted- you should be able to tell that the engine is working near 100% efficiency until 5500rpm. That is a very healthy curve. There is barely any room to "tune" around that. I am sure it could be squeezed for a bit of power, but a cold day comparison would do the same thing. Plus, what is there to 'tune' besides throwing timing at it? Timing which will only move the motor closer to the brink of destruction.
IMO Do not tune it until your a/f start to wander away from ideal. A solid curve to 5500 doesn't please anymore? Then look at airflow mods (camshaft duration increase) which move the curve up, you can give up something around 3k rpm to gain after 5500. But then you are winding the motor higher and higher for a dyno number increase, which may not serve you well from stoplight to stoplight on the street (you rev to 6k+ everytime you leave the light? Otherwise what was the point of moving power up there)
Now he has to do a full tune, if he wants to keep the kn air filter
"the full tune" Is a misnomer. What tuning is there? It needs a code or CEL turned off? That is not tuning.
It all depends on cost, like I said from budget perspective. A 'tune' if necessary accounts for any number of variables: new heads, cam, turbo, trans, tires, gears, stall, accessories, etc... so if there is going to be a moment when you pay for a 'tune' it should include as many or all of those variables at that time.
One of the last codes I'd want turned off would be lean codes. This sounds like it still might need A/F and timing played with but need to eliminate other basics first. There COULD be a vacuum leak somewhere or maybe even more likely, dirty injectors. Those lean codes aren't for nothing. This needs a proper troubleshooting exercise...
05-15-2017, 02:09 AM
Had the V on the Dyno 
