LTs w/HF & CAI + Tune and Thoughts
 

Hey everyone, I just got my first round of mods and I wanted to share what I got, why, and how it turned out.

What I got:
- American Racing Headers Long Tubes
- High Flow Cats
- RotoFab CAI
- TR7IX Plugs
- Tune for 91 octane (I live in California).

Why:
I traded in my 2013 Shelby GT500 for this car and there was very little that I missed. Power wasn't an issue, the difference seemed minor enough, however I did want more sound, drop a little weight (up front if I can), and get the car to run right on 91 octane as I was experiencing some minor knock on my crappy local gas.

How it turned out:
For now I won't say where I went to get the work done because my review is very subjective and I don't want to cause any negative feelings...

I did not get a baseline dyno. Apparently I asked for it too late, I thought this was standard practice but thats my bad for making the assumption. Given the lack of baseline dyno, I don't really know how much power I made but my gut tells me I was below average given the crappy 91 octane and VERY VERY frequent knocking, though minor, still enough to cause a significant retard and always running in the low octane table.

So based on those details above, my gut tells me I would have been below average baseline... maybe 475, not because it was a low reporting dyno but because of the crappy gas. After all is said and done, I got 530rwhp. If my guessing is right (and thats a big IF), then thats about 55rwhp gains? and that is about in line with where I expected. I specifically asked for a VERY VERY SAFE TUNE.

In any case, more than numbers -- how does it feel?

Sound:
The sound is phenomenal. It sounds like a banshee when I do WOT blips. I love it and have zero complaints, this landed exactly where I wanted. Great growl when I'm on it, far better than you hear on youtube and far far louder so be careful. I'm actually scared to romp on it in town now because I'm certain I'll get pulled over... Awesome. CAI woosh sounds nice too plus a little extra supercharger noise, all good.

The knocking:
Completely gone as far as I can tell, but that is only seat of the pants for now. I have an HPTuners reader and will do more diagnostics soon but I'm well pretty convinced it's running knock free. So this was my primary concern and all seems well.

Performance-Weight:
Believe it or not I can actually feel the weight loss, hopefully it's not just my imagination, but even if it is, I like it. Can't say for sure how much I dropped -- I'm crossing my fingers at maybe 50lbs off the front of the car between the Long Tubs, cats and mid-pipes.

Performance-Driveability:
This is where I may need some getting used to, or maybe something isn't running right and I'm a bit disappointed. I definitely do not "feel" any power gains, maybe even a bit of loss in low end torq and maybe some high end power? It's difficult to gauge because I rarely went WOT with the car before since I was afraid of the knocking. This may just be the first time I'm really able to feel the power of the car and its coming up a bit shorter than I hoped, whatever I'm not too worried about this -- if I don't acclimate then I'll get it dyno'd elsewhere for a second opinion.

The last thought on driveability is, I seem to have gained a hesitation when stepping on the throttle. Maybe this is from the less restrictive headers (total guess)? In any case, now when I go WOT the boost kicks in 1/4 of a second later where it used to feel instant. I wasn't expecting this and not sure if its normal.

Here's the result dyno sheet:

http://aarontharris.smugmug.com/phot.../i-nmR48DK.jpg

Out of curiosity, I compared my dyno to a stock ZL1 dyno I found here: Stock ZL1 Dyno and when I look at the curve, it seems like my car is roughly the same #s as a stock car except a bit better top-end, which confirms my butt dyno.

So all things considered, my $ $ $ earned me sound, got the car running right on 91 octane and got my power levels back up to stock plus a little... Considering all that cost me $4k and I should have gotten that from the factory (except the sound), I'm a little irritated but really like a 1 on a scale of 5 haha.

A pulley swap maybe in order. Numbers look right with upgrades listed on 91-octane, keeping in mind that dyno numbers are all relative.


Sent from my iPad using Tapatalk

Haha, pulley swap definitely in order!

I just got a tune, long tube headers, id850 injectors, 90mm throttle body and a 10% pulley. Car dynod 478hp with just the rotofab when I brought it to the shop. Left the shop at 572hp can honestly say I'm extremely suprised at the gains for an auto. I'm still in the air if I want to keep the headers in california... I wasn't expecting the car to gain that much noise at wot. Seems like nothing but trouble for me since I can't keep my foot out of the car... and I can't hear my supercharger over my exhaust anymore I miss that noise alot alot

Keep the headers. :headbang:

Did they street tune it or just WOT on the dyno? You shouldn't have any of the issues noted and the throttle response should be instant as well as the boost kicking in quickly.

headers & CAI can cause a bit of off idle sogginess that will subside as the rpms climb. If you get a pulley upgrade, it will raise your eyebrows. Your overall power is up now, but boost comes on slightly slower and your powerband rpm has shifted up. Don't be disappointed as your situation is easily fixed if you go as low as a 10% overdrive lower pulley. You should go with a 9.17" lower (18%) so you will be within the limit of stock injectors. If you want more, upgrade to ID850's and put a 10" lower ring and you will have a permagrin!

What you described is exactly what I'm experiencing. I believe it's normal.

I will definitely do a pulley upgrade but I'm going to try to pace myself as best I can ;)

I'm thinking maybe I need to add resinators to the exhaust. Right now I'm catless so gonna add cats first and go from there. Also have the npp fuse pulled might need to plug that back in. Can you hear your supercharger with the hi flows angrybits?

I just confirmed with my HPTuners tool, there is ZERO, absolutely ZERO knock retard at all RPMs, climbing a hill, down a hill, cold weather, hot weather (it's 80deg and sunny where I live, but 60deg and foggy literally 5 miles away). Everything checks out well. Almost as if I forgot to datalog the KR... But I double checked ;)

Attached is my HPTuners cfg and data files for curious eyes.

.

I can but barely. I actually prefer the sound of the engine over the supercharger.

The car sounds like its running open headers -- just straight up Indy Car! It actually makes my Shelby sound like an old beater muscle car and my ZL1 like a modern race car. Even though as far as engines go, its kind of the other way around. Whatever, I love it!

If you're in CA, I'd definitely put the cats back on.

Pulley it
 

Pulley it and you will hear it over headers....

It is pullied 10% my exhaust is just freaking loud