Bolt-ons and not very happy with results....
 

Hey Forum,

Here's what I did:

Roto-fab dry CAI - installed by me
Soler Engineering TB - Installed by me

Car ran fine no issues, somewhat better throttle response for a couple weeks

Next, (all installed by local speed shop)
Speed Engineering 1 7/8 long tubes
Speed Engineering 3" catless mid-pipes
Stainless Works NPP 3" in axle back
Flex fuel kit
Tune for E85 and 91

Dyno was 419HP and 448TQ (said it was because E85 was more like E50?? and a HOT day, >100 degrees) :thumbdown:

I was thinking should have been more like 440HP. Car is definitely quicker but is just too loud for my taste. I'm talking "piss off the neighbors" loud. I know I'm 53 but dang I'm not THAT old. I've been driving in Stealth mode and still too loud. I had the same set-up (almost) on my C5 Corvette and it wasn't nearly so loud, it did have catted mid pipes tho. I like a good deep growl but sheesh. I keep setting off others car alarms at work when I start it.

If I go with 3" in/out cats will that tone it down (and make it legal) or should I do something else?

FYI, I have factory NPP and had been driving with fuse 51 out and liked it but a little louder would have been fine with me. This is A LOT louder.

Any advise will be appreciated.

https://scontent-lax3-1.xx.fbcdn.net...32&oe=5DD0E7C0
https://scontent-lax3-1.xx.fbcdn.net...93&oe=5DE94C90
https://scontent-lax3-1.xx.fbcdn.net...c7&oe=5DC7C09B
https://scontent-lax3-1.xx.fbcdn.net...82&oe=5DC9E24E

Yes, 1 spark plug boot is touching the header on each side so I have heat shields on the way.

Link to start-up video:
here

So you're saying you dyno'd 419hp after all parts were installed? If so, that doesn't sound right. Might be in the tune. As for the sound, should have done headers first to see how tolerable it is and go from there. I say switch back to the OEM exhaust and see if that does the trick.

I had heard a stock NPP with headers and did not like it, that's why I went with the Stainless Works NPP.

tune sucks. and really since we are talking corrected HP, it is making more even less HP to the wheels. What is the uncorrected HP? Also all that no-cat SS 3" stuff does not add much HP... just saying. check for burned plug wire too.

I am gonna agree with Oldman, the tune is suspect.

Most of the HP gained from E85 is had by the time you hit E50. On a N/A engine from E50 to E85 you are only going to see 5-7 more rwhp.

With similar mods as you during he heat of summer I made 424rwhp with catless headers, Roto-fab CAI, and a Pray ported TB/IM combo. When I added E85 to the car and retuned I got the gas tune to 431rwhp on 91 and 455rwhp on E85 that was at E60.

Get the intake manifold ported by pray. Can you post the dyno graph

419 is at the wheels from the Dyno graph.

Don't yet have the file in hand, they are supposed to email me. Said if I come back with a fresh tank of E85, they will run it on the Dyno again.

I did and am still considering the Pray ported IM.

Will do. Headers are coated tho.

Cordes might be close to you... they can port as well

What was the dyno baseline?

What lambda was the car running post-tune for 419hp?

And what about torque before/after?

I figured that but I wanted to get rid of the AFM valves altogether. The SE LT's with the full length 3" mid pipes was only $650. Plus the LT's outlets are 3" and so are the SW NPP mufflers inlets.

I know, I wanted go with them first but they wouldn't touch the SE LT's and thier tune was much more expensive. I went with Extreme Motorsports cause they did my C5 Corvette years ago and did a great job.

Yup that’s partly why I wanted the graph to see the lambda

You can still burn a plug wire even with coated headers.

Get Brett / Pray Performance to do your tune remotely. He will get it straightened out in no time and is probably the best 6th gen guru out there. There are other quality guys out there like GPI and Jannetty but I've only dealt with Brett and he's amazing, he really understands these cars.

Email him datalog and he'll send you back a tune. His pricing is on his Facebook page.

Uugh!!! So I would have to buy a hand held and pay for another tune?? :mad:

It'll be worth it! The best $$ you'll ever spend on your car.

Yeah now you’re down this path I would give him a chance to fix it. Prays tuning plus the hptuners is not a cheap option especially if you already laid out cash for this tune. I would get the intake ported and give him a shot to fix it. The shame is you couldn’t have cordes do it from the start. I wonder if they would’ve been ok with Texas speed headers

I would not throw good money after bad.. a bad tune can mess your ride up. Pray and Cunningham are been both excellent top notch. Other vendors here have stellar reps. Just look at JDP's dyno... simply amazing.

#s seem a little low for those mods. Maybe, have the re-check everything. i totally feel you on loudness. i recently replaced my stock Npp with a magna flow npp axle back and have instant regret. So loud and the drone is insane. i think your best bet is going to be oem Npp. I know I'm going back to stock npp. i may look for a zl1 npp with the larger tips.

Should have brought it to JDP. They get 455HP without the Exhaust or E85.

I run long tubes, gutted cat (cats clogged up) with NPP and made 830 rwhp/779 rwtq. Npp doesn't care, pull the fuse as I did with 500 miles on it. They are open all the time.

Just wondering but are you concerned about the heat release profile and egt with that not being a straight through muffler at your power level?

I’m def feeling better about running it bolt on tho

They did not do a "before" dyno run.

Some of my friends suggest to line the trunk with sound proofing. Maybe under the back seat as well.

I spent good money on what I have and like the tone/sound, just need to take it down a notch in volume.

If I'm getting it re-tuned, I'm going to nickD at CPR. He's pretty much the premier tuner in the entire southwest if not more. I have heard great things about Pray but would rather have someone "hands on".


As I said I went with Extreme Motorsports as I have history with them and CPR would not do what I wanted parts wise. I guess EM is not what they were.

I'll take the car back in and give 'em a chance to fix it and let you all know.

Not quite sure of your point, I ran mine stock with the fuse out also cause I liked the sound and it was not excessively loud.

When I was planning my build I listened to cars with LT's into the NPP and did not like the tone/sound, too high pitched and raspy for my taste. I prefer a nice low tone "classic" muscle car growl and the Stainless Works NPP sounded like what I wanted. Just didn't know it would be be so LOUD. :bonk:

So your saying that JDP can get 455 at the wheels with CAI and ported TB/IM alone, no E85?? :twitch:

According to their web site, their stage 1 with CAI, Katech TB, MSD IM and tune will gain 45HP. Our cars stock (for A8) is ~ 380 - 385 HP at the wheels, add 45HP and that nets ~430HP max at the wheels.

The mods I have should have gotten me closer to 450HP at the wheels.

With tuning: (conservatively)
Roto Fab CAI - 10HP
Ported Soler TB - 5HP
LT's with off road pipes - 30HP
Flex fuel - 20HP

= 450 WHP

Or am I wrong??

I’d agree with most of that.

Flex fuel is worth 20hp over a 93 tune(10hp) so 30hp total

Or LTs are worth 20

Tb plus rotofab I’d say 10hp together

But yeah you’re not close. There’s something off.

I wanted to see the latest graph. the fueling will let us know if they remotely understand tuning a gen 5

MrRuss:
I had kind of the same issue with the very loud exhaust. My 2016 1ss setup has the StainlessWorks headers. I paired it with the same brand muffler = piss the neighbor bad.
My local muffler guy suggested the Borla mufflers. Went that way, problem solved! Only loud when you step on it hard. Otherwise you can cruise and no drone. Hope this helps

i made 422.5 from a mustang dyno, no tune with just Rotofab CAI. so those numbers are def off by a lot. you need to get it re tuned by someone who knows what they're doing.

I put down 413 to the rear wheels bone stock. Of course that's changed just a bit with the
ProCharger, lol!

whatre you at now? lol

JDP has a post here. Check it out

what does the car trap? what kind of dyno? putting any stock in final dyno numbers is silly, to say the least.

In this case I have to disagree. There are LOTS of "tuners" that have tuned LS motors and Mustangs that will happily take your money to tune your 6th Gen or C7.

Very FEW of them know a damn thing about what they're doing on these.

A GM performance specialty shop up here in the North GA mtns did a cam package on my buddy's 16 Camaro.
He blew his engine a week later tune was completely off and owner supplied a newish motor but still 2 months of downtime...

Local long time GM specialty shop did my Heartbeat install then owner tuned it.
Completely screwed up the tune despite post tune dyno reading 589 whp
Lol
Took it to Vengeance Racing and Mike took care of it.
He sat down with me and showed me everything screwed up with it. Now it is running right.

100% don't trust your LT1 to anyone but a very reputable tuner who has DOCUMENTED work/builds/customers with these specific cars. It is a very expensive lesson.
$900+ for me...

what exactly are you disagreeing with? i don’t see where you made the connection. your post regards the tune itself, not the final number vs real world performance, as my post did. i made no reference to the quality of tune.

In all honesty - the number IMO isn't that far off, particularly for running E50. All of that exhaust work is going to net you maybe 6-8 peak hp.

First the fuel - E50 is 50% ethanol and 50% 87 octane gasoline, which nets you 93-95 octane. Get a good batch of E85 into it and that alone will jump 10pts. You had no advantage over premium pump gas.

Second - though they are solid upgrades, most of your mods are the type of thing you need to support more air flow thru the engine. The factory exhaust is pretty much maximized right from the factory for the airflow the engine makes stock. Eliminating the cats did more for you (power wise) than everything else. The factory manifolds on the LT1 are actually not that bad flow wise, and the rest of the exhaust is 2-3/4". A lot of the headers advertise 12-20hp, but that also includes a tune.

Good news is that you are setup to go full smack in the future. Throw in a BTR Stg2 cam and a good tank of E85 with a retune and you will probably pick up 40whp as you have all of the other supporting mods.

I agree, on full E85 mine made 431 with basically the same mods and I picked up 5-6 mph at the track so I know it was making a lot more power. Dynos can read all over the place, that is why you get a baseline and then I final to see how much you picked up. On a cooler day with more alcohol content your dyno would probably be close to mine. I laugh when I see these guys boasting these huge dynos where the car made 460 rwhp with just a CAI and muffler delete, I always ask what does the car trap? Dynos can be configured to read anything people want but trap speed will always tell the truth.