My initial thoughts on LS6 manifold install on a pretty much stock LS1 99 coupe - CorvetteForum - Chevrolet Corvette Forum Discussion

Go Back  CorvetteForum - Chevrolet Corvette Forum Discussion > C5 Corvettes, 1997 - 2004 > C5 General
Reload this Page >

My initial thoughts on LS6 manifold install on a pretty much stock LS1 99 coupe

Notices
C5 General General C5 Corvette and C5 Z06 Discussion not covered in Tech
Sponsored by:
Sponsored by:

My initial thoughts on LS6 manifold install on a pretty much stock LS1 99 coupe

Reply

 
 
 
Old 07-15-2018, 11:28 PM
  #1  
acuevo
CF Senior Member
Thread Starter
 
acuevo's Avatar
 
Member Since: Aug 2008
Location: New Jersey
Posts: 332
Thanked 62 Times in 48 Posts
Default My initial thoughts on LS6 manifold install on a pretty much stock LS1 99 coupe

Hoping this can serve as some good info for any other guys like me who are getting to the point where they can finally afford their own vette. OR for guys who have had one for a while who have decided to do some mods.

Finally picked up an LS6 manifold on the SUPER cheap a few weeks ago ($325 from a 26k mile Z) - in great shape. Drove it when I originally installed and saw a noticeable difference. It seems to pull just a little harder, surprisingly its most noticeable in the lower rev range. I was expecting to only really notice top end but I can definitely feel the change from 2k and up. Not sure what real world numbers it gave me, I won't have it to a dyno for quite some time (probably not till I finally cam it). Don't misunderstand, this is a small change... it's not like its suddenly an 11 second car, but you CAN tell the difference. Its easy to see why when you have the manifolds next to each other - even though you can't really see the runners inside you can tell how much extra volume the LS6 manifold has by looking at the bottoms. So a lot of the difference could all just be in throttle response.

I actually first installed earlier this week, but just had it back off for peace of mind. At first, I chiseled off the ribs in the manner that can be found all over the internet to clear the cross over pipes. I noticed it would still rock significantly from drivers rear to passenger front when sitting in its guides without being tightened. Seemed like the front knock sensor wire was holding it up just a little bit. Even though it torqued down with no leaks or driveability issues I wanted to be sure I wouldn't be soldering a knock sensor wire in the future. So I took it all back apart and routed the wire UNDER the crossover pipe instead of over and it helped a lot. Still not completely laying flat on its own but I'm more confident now there won't be any damage to the wire. Side note: that rear vacuum line is my mortal enemy.

So for any guys wondering if its worth it, I say definitely. That is if you can find one at a decent price and in decent shape. The install wasn't bad, just a little tedious. If you can wrench a little bit on cars you should be fine, plus like I said there's tons of info on the web.

Also I have to say, it's been just a little over a year since I got the car and I still get a thrill just by starting the thing. 17 years of wanting one finally paid off and I wasn't disappointed in the least!
acuevo is online now  
Reply With Quote
The Following User Says Thank You to acuevo For This Useful Post:
pjdbm (07-16-2018)
Old 07-16-2018, 12:01 AM
  #2  
pjdbm
CF Senior Member
 
pjdbm's Avatar
 
Member Since: Mar 2017
Location: Long Island New York
Posts: 604
Thanked 73 Times in 68 Posts
Default

Sounds great! did you take any pictures? did you keep the stock throttle body?
pjdbm is offline  
Reply With Quote
Old 07-16-2018, 12:36 AM
  #3  
acuevo
CF Senior Member
Thread Starter
 
acuevo's Avatar
 
Member Since: Aug 2008
Location: New Jersey
Posts: 332
Thanked 62 Times in 48 Posts
Default

I meant to take some pictures but unfortunately I forgot to. I don't think there is a whole lot of difference between the pre and post 2001 throttle bodies so I just stuck with the stock one. I think the later ones are just a few millimeters wider so its not a huge difference.

Its also worth mentioning its a good time to replace a few other things. I did the PCV valve and new injector o rings with this. Thought about doing the oil pressure sender as well but I peeked in before hand and mine had already been replaced with the aftermarket brass type which is supposedly more dependable so I left it alone. A lot of people seem to get them from O'Reilleys but I'm pretty sure auto zone or advanced has them too.
acuevo is online now  
Reply With Quote
Old 07-16-2018, 12:44 AM
  #4  
pjdbm
CF Senior Member
 
pjdbm's Avatar
 
Member Since: Mar 2017
Location: Long Island New York
Posts: 604
Thanked 73 Times in 68 Posts
Default

This is something I would consider, I am also stock with just a Vararam CAI, Borla exhaust & diablo tune. I am pretty sure I will NOT do headers and I am liking the way the car runs now. The Vararam did make a noticeable
difference.
I will keep my eyes open for an LS6 intake and maybe it will be this winters project.
pjdbm is offline  
Reply With Quote
Old 07-16-2018, 12:47 AM
  #5  
acuevo
CF Senior Member
Thread Starter
 
acuevo's Avatar
 
Member Since: Aug 2008
Location: New Jersey
Posts: 332
Thanked 62 Times in 48 Posts
Default

I would definitely say if you see one, jump all over it. The 325 I paid was really a steal, the cheapest I had seen before that was about 450. Another option is the Dorman aftermarket LS6 manifold, which will flow much better than the stock ls1 but not quite as well as the GM LS6 part.

Last edited by Vetteman Jack; 07-16-2018 at 09:54 AM.
acuevo is online now  
Reply With Quote
Old 07-16-2018, 09:38 AM
  #6  
jjc508520
CF Senior Member
 
jjc508520's Avatar
 
Member Since: Aug 2014
Location: East Windsor NJ
Posts: 1,162
Thanked 91 Times in 80 Posts
Default

I did the LS6 intake (installed by ECS) and then later ARH headers with dyno tune - it runs well for a "bolt-on car".....
jjc508520 is offline  
Reply With Quote
Old 07-16-2018, 09:55 AM
  #7  
Vetteman Jack
Moderator
Support Corvetteforum!
 
Vetteman Jack's Avatar
 
Member Since: Mar 2001
Location: Heart of Missouri Currently Own: 2003 Milestone Edition. Previously Owned: '79, '79, '84, '89, '94, '95, '99 and '00
Posts: 258,837
Thanked 3,166 Times in 2,816 Posts
MO Events Coordinator
St. Jude Co-Organizer
St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16-'17-'18
NCM Sinkhole Donor
CI 5, 8 & 11 Veteran

Default

Nice start to your modding of the car.
Vetteman Jack is offline  
Reply With Quote
Old 07-16-2018, 10:43 AM
  #8  
grampi50
CF Senior Member
 
Member Since: Sep 2016
Posts: 2,010
Thanked 244 Times in 194 Posts
Default

Since the LS6 intake flows better, does it require a retune? Seems like it would be tuned too lean for this intake...
grampi50 is offline  
Reply With Quote
Old 07-16-2018, 11:10 AM
  #9  
'Shifter
U*S*A-Love It or Leave It
Support Corvetteforum!
 
'Shifter's Avatar
 
Member Since: Oct 2006
Location: Trump is your President, deal with it!
Posts: 11,803
Thanked 130 Times in 116 Posts
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16-'17
NCM Member '09

Default

I sell the Dorman version, and have thought long and hard about this swap as a base for more mods down the road. Is there a reputable company that does a decent port-job/casting clean-up that anyone has experience with?
'Shifter is online now  
Reply With Quote
Old 07-16-2018, 02:52 PM
  #10  
acuevo
CF Senior Member
Thread Starter
 
acuevo's Avatar
 
Member Since: Aug 2008
Location: New Jersey
Posts: 332
Thanked 62 Times in 48 Posts
Default

Originally Posted by grampi50 View Post
Since the LS6 intake flows better, does it require a retune? Seems like it would be tuned too lean for this intake...
I over research everything I do in life from my cars to my guitars. Never saw an instance of someone needing a tune from the ls6 manifold on a stock car. From what I understand, a tune is worth up to 10hp on a totally stock ls1 as they come from the factory leaning on the rich side for safety, so I don't think anyone would have an issue with it running too lean, even with a CAI (which I also have).

As always, I could be wrong so if anyone knows other wise please do chime in.
acuevo is online now  
Reply With Quote
Old 07-16-2018, 03:13 PM
  #11  
grampi50
CF Senior Member
 
Member Since: Sep 2016
Posts: 2,010
Thanked 244 Times in 194 Posts
Default

Originally Posted by acuevo View Post


I over research everything I do in life from my cars to my guitars. Never saw an instance of someone needing a tune from the ls6 manifold on a stock car. From what I understand, a tune is worth up to 10hp on a totally stock ls1 as they come from the factory leaning on the rich side for safety, so I don't think anyone would have an issue with it running too lean, even with a CAI (which I also have).

As always, I could be wrong so if anyone knows other wise please do chime in.
I've also read the stock tune is a bit on the rich side (which seems weird to me considering everything GM did to the C5 to increase it's fuel efficiency), but I didn't know if it was rich enough to handle more intake air....sounds like it is though!

grampi50 is offline  
Reply With Quote
Old 07-16-2018, 07:57 PM
  #12  
C5 Kirkland
CF Senior Member
 
Member Since: Dec 2017
Location: Kirkland WA
Posts: 219
Thanked 16 Times in 15 Posts
Default

Originally Posted by acuevo View Post


I over research everything I do in life from my cars to my guitars. Never saw an instance of someone needing a tune from the ls6 manifold on a stock car. From what I understand, a tune is worth up to 10hp on a totally stock ls1 as they come from the factory leaning on the rich side for safety, so I don't think anyone would have an issue with it running too lean, even with a CAI (which I also have).

As always, I could be wrong so if anyone knows other wise please do chime in.
CAI/TB/manifold/LTH/exhaust-Tune
Cam/Heads/Injectors-Tune
Supercharger or Turbo-Tune

Last edited by C5 Kirkland; 07-16-2018 at 07:59 PM.
C5 Kirkland is offline  
Reply With Quote
Old 07-17-2018, 03:10 AM
  #13  
sirdano
CF Senior Member
 
sirdano's Avatar
 
Member Since: Jul 2015
Location: Round Rock Texas
Posts: 612
Thanked 54 Times in 51 Posts
Default

Originally Posted by grampi50 View Post
Since the LS6 intake flows better, does it require a retune? Seems like it would be tuned too lean for this intake...
Lean is real bad it is like a tourch to your pistons. When I took my car to get tuned the tuner told me is was running super lean. I am glad i got it done
sirdano is offline  
Reply With Quote
Old 07-17-2018, 11:03 AM
  #14  
jackthelad
CF Senior Member
 
Member Since: Jun 2013
Location: West Virginia
Posts: 1,860
Thanked 167 Times in 141 Posts
Default

Originally Posted by acuevo View Post


I over research everything I do in life from my cars to my guitars. Never saw an instance of someone needing a tune from the ls6 manifold on a stock car. From what I understand, a tune is worth up to 10hp on a totally stock ls1 as they come from the factory leaning on the rich side for safety, so I don't think anyone would have an issue with it running too lean, even with a CAI (which I also have).

As always, I could be wrong so if anyone knows other wise please do chime in.
There were changes to the factory tune made between the early cars - which had slightly larger injectors, and no pup cats, and the models with the pup cats and smaller injectors and the LS6 type intake manifold as standard. Later on, they went back to the larger injectors.

When I put my Halltech Stinger on, the PCU seemed to adjust to the new reality after a few miles, and seemed (I emphasize seemed) a little stronger. I do know that when the K&N folks made kits for both early and later cars, their dyno pulls showed the early cars picked up more power than the later ones. Prob due to being a bit richer ex-factory. Similarly, when Lingenfelter first started modding C5's, part of their package for later cars was to instal the bigger injectors as fitted to the early cars.
jackthelad is offline  
Reply With Quote
Old 07-17-2018, 09:59 PM
  #15  
redzg
CF Senior Member
 
Member Since: Mar 2017
Location: Orlando Florida
Posts: 639
Thanked 75 Times in 72 Posts
Default

Well crap. I have a LS6 manifold in the garage, waiting for install. Was kind of hoping you were going to say it wasn't all that impressive and I could wait until I can pop for the 243s to go with the manifold and Z06 cam (also in the garage). Cam will still have to wait, but the manifold will have to go in.
redzg is offline  
Reply With Quote
Old 07-17-2018, 10:19 PM
  #16  
acuevo
CF Senior Member
Thread Starter
 
acuevo's Avatar
 
Member Since: Aug 2008
Location: New Jersey
Posts: 332
Thanked 62 Times in 48 Posts
Default

Originally Posted by redzg View Post
Well crap. I have a LS6 manifold in the garage, waiting for install. Was kind of hoping you were going to say it wasn't all that impressive and I could wait until I can pop for the 243s to go with the manifold and Z06 cam (also in the garage). Cam will still have to wait, but the manifold will have to go in.
With my luck you won't notice a difference and I'll have to eat my words LOL. Good luck and let me know how it drives after the install!

Last edited by acuevo; 07-17-2018 at 10:19 PM.
acuevo is online now  
Reply With Quote
Old 07-18-2018, 08:56 AM
  #17  
Gordy M
CF Senior Member
 
Member Since: Feb 2001
Location: Plymouth MI
Posts: 1,899
Thanks: 0
Thanked 107 Times in 103 Posts
Default

The main advantage to having the 2001-2004 intake is the increase in torque. GM was only able to find 5 more hp but 25lbs more of torque in 2001+ LS1 vettes.
Gordy M is offline  
Reply With Quote
Old 07-18-2018, 07:24 PM
  #18  
EVLGTO
CF Senior Member
 
EVLGTO's Avatar
 
Member Since: Oct 2006
Location: San Diego CA
Posts: 605
Thanked 15 Times in 14 Posts
Default

I also did this mod a couple of months ago and it was completely worth it. I found the intake here in the forums for $200 off a 40k mile 04 C5. The best thing of all was, dude was local! I ground down the ribs under the manifold completely. I smashed down the steam tubes very slightly, enough so the manifold wouldn't rock back and forth. My C5 pulled way harder down low and towards the top of the power band. You will feel the difference without a tune, but the LS6 intake is not completely being optimized until the car has been properly tuned. I will be installing a cam very soon, so I will have my car tuned after the cam.
EVLGTO is offline  
Reply With Quote
Old 07-18-2018, 10:10 PM
  #19  
Pounder
CF Senior Member
Support Corvetteforum!
 
Pounder's Avatar
 
Member Since: Jun 2014
Location: Shawnee Oklahoma
Posts: 9,289
Thanked 1,356 Times in 1,149 Posts
Default steam lines

you should have installed a steam line kit instead of grinding the manifold, really helps the cooling of the rear cyl. !!!!! (don't have to bleed the air out ether !!!)
Pounder is offline  
Reply With Quote
Old 07-19-2018, 09:46 AM
  #20  
pjdbm
CF Senior Member
 
pjdbm's Avatar
 
Member Since: Mar 2017
Location: Long Island New York
Posts: 604
Thanked 73 Times in 68 Posts
Default

Did you get rid of the EGR? I am looking into this.
pjdbm is offline  
Reply With Quote

Thread Tools
Search this Thread
Quick Reply: My initial thoughts on LS6 manifold install on a pretty much stock LS1 99 coupe


Sponsored Ads
Vendor Directory

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: