2015 Stingray Convertible 3LT auto 20kmiles, think it has Z51 but will verify

Helping a friend with some mods, he is ordering a set of Kooks headers, already has cold air and is interested in a tune, I dont recall if there is an ECU flash, is there? Any other ideas for bolt ons or performance enhancements other than FI or nitrous? He is just wanting to have some fun and make the car a little faster/better sounding.

Also, anyone know shop time for the header install?

Thanks in advance

 

LT1 or LT4? My shop needed 4-5 hours for LTs on my Z06. He'll need to go to a tuner or buy an HPTuners MPVI2 from someone who will give him remote tunes based on data logging (will require a Wideband O2 in the headers).

If he's going to get a tune and has access to E85 he might consider putting an E85 sensor on the car, it's a couple hours to install and isn't very expensive. LT1 would see 50-60ish rwhp on full E85, LTs, CAI, and tune. LT4 probably won't be able to go beyond E40/50 but he'd see 75ish rwhp. If it's an LT4 he could add an upper pulley for not much added cost also, a couple pounds of boost is 40-50 rwhp but does increase heat under the hood. Might as well do all the mods that require tuning at once to avoid paying for re-tunes. Just my .02...

 

Telling me it will need a Y pipe as well? Does that sound right? Its an LT1, stock with the exception of the CAI

50-60hp would be huge, is it really that much???

 

There are no Y pipes on C5, C6 or C7 Corvette's of any spec.

 

No Y-Pipe, I wouldn't listen to whoever is telling you that or let them touch his car. The LTs come with their own X-pipe so it is a complete exhaust that bolts to the OEM axle-back. Yes, E85 really wakes these cars up. Headers add 25ish when tuned and the E85 will easily add that much or more once the tuner tells the ECU to use the sensor. It automatically adjusts timing for the level of E in the tank so you can run 93 only or full E85 and anything in between. Do a search in the C7 forums here and you'll find lots of LT1s with just E85 and a CAI or E85, LTs, and CAI and you can see what they're putting down.

The following thread is a guy who's an excellent driver but he went almost .9 quicker in the 1/4 from just E85, LTs, and CAI with the proper tune on his LT1. You can see he was almost .5 quicker from just E85 so most of his gains are from the E.
https://www.corvetteforum.com/forums...-18-124-a.html

 

Thank you. Looking around, it does show just a header assembly from Kooks (21702400) but when shopping around, I see LG has a LT that includes the x/y pipe as a package. Looks like the LG setup would actually be cheaper.

Thanks for the info on E85, def adding that to the to do list

 

I should have asked here first what combo of mods I should be considering......

 

You will have to get the matching Kooks X-pipe as well, they just sell them separately from what I remember. No LT headers will mate up to the OEM X-pipe but American Racing does make a mid-length header that will if you want to go that route. They make about half the power of the LTs on the LT4, not sure how close they are on the LT1 to be honest, probably within 10 rwhp. Another option is to just buy the down-pipes that replace the pipe from the OEM manifolds to the X-pipe including the cats. They will make similar power to the mid-length ARH headers at similar cost but are much easier to install. The OEM manifolds do flow pretty well, the major restriction is in the mid-pipe with the main cats.

My personal opinion: LTs, even when using the high-flow cats, are very loud even with the OEM NPP exhaust so, if you like that, then go for it. If not, I'd do the mids or the down pipes with an off-road X-pipe to tame down the sound a bit at the price of leaving some power on the table. Cats or no cats is up to you, they don't really rob any hp anymore. No need to mess with the OEM axle-back. Exhaust, E85, and a good CAI with a tune will net you very good gains and those are the most common mods for folks who like the drag strip from what I've seen. Heck, even just E85 and a good CAI will net you good gains with a tune if you need to pass emissions.

 

That sounds good, I am trying to find a good E85 solution, maybe even do that first, home boy just wants to burn some cash and make some noise. Any opininon on LG's LT/xpipe setup? Looks to be cheaper and used to watch Lou back in the day.

Thanks much for the detailed response!!

Also, is the LT swap MAJOR surgery? I am sure its not easy, but is there anything crazy about making the swap if you have the right parts? The Chevy store is going to do it, but there Vette tech is on vaca till next week and they wont quote me until he weighs in.

 

Most folks on here would agree that Kooks and American Racing will have the best fit for the LTs. Lots of folks have the LGs as well from what I've seen but you get what you pay for in terms of fit. The install isn't too terrible but it involves removing the oil lines from the oil cooler and maybe the starter potentially along with plug wires, and a few other things. It's a solid 4-5 hours with the X-pipe for someone who knows what they're doing. The LT1 is easier than the LT4 mainly since we've got a blower on top to deal with and most LT4s go with 2" instead of 1-7/8" so that makes it really tight.

 

I have a Z51 and installed Corsa 1 7/8 Long Tube Headers. Fitment was perfect and I didn't have to remove the oil lines. Although I have the Corsa X-Pipe, they do fit up to the stock X-Pipe.

 

I was quoted 6hrs per side, base, and 7.5hrs per side if Z51, GS, Z06 (dry-sump).

 

From previous post I would research fitment issues. I installed KooKs LT's and their off-road x-pipe, and everything bolted up nicely to my factory exhaust. I have had a few friends install some off brands and had some issues with fitment.

Side Note - Make sure your O2 sensor wires are heat wrapped properly.