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Discussion Starter #1
Took delivery in March, GTO M6 ,and have been studying approches to engine mods.Great site ,thought I would share some stuff with everyone....The best investment seems to be to opt for the Ls6 heads and cam(zo6 vette) COST WILL BE ABOUT $1800 FOR PARTS ,$500.00 Labor.Should pick up 405 hp gross 360 or so rwhp.My research indicates lifter,push rods,rocker arms,since they are rollers ,can be reused( UNLIKE FLAT TAPPETS) ,Need new head bolts etc but thats in the cost.Now compare the gains and costs compared to a new exhaust at $600.00 or so and a CAI for a FEW BUCKS(with almost no HP gain )Also,spoke to Diablo today and their # 193 predator for the Ls1&lS6 WILL UPDATE TO ZO6 SPECS,that is the fuel,ignition maps and the fuel cut can be increased.Stock GTO Throttle body& MAF are compatible ( Zo6 MAF is good for 3 hp and not worth the $260,00...Keep in mind we have the Ls6 Block and intake.In my view this is an excellent compromise,really good HP gain,retain excellent reliability,good fuel mileage ,keep the excellent stock ehaust( same headers as the Zo6 vette),stock cold air intake,at a cost of about $40.00 per HP.I am not a drag racer ,just want something a little different but with good reliabilty etc.Seems to be a sensible approach.GM says the typical engine design considers 125,000 miles as the reliabilty bench mark so the Vette LS6 ZO6 parts bin looks pretty good.

You guessed it,the parts are on order.Going to Dyno this week to establish a base line but the Predators on back order for 2 weeks and will not start till I have it

Your thoughts and comments are welcome
 

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Knight Errant
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As long as you are going for heads...

scheer said:
Took delivery in March, GTO M6 ,and have been studying approches to engine mods.Great site ,thought I would share some stuff with everyone....The best investment seems to be to opt for the Ls6 heads and cam(zo6 vette) COST WILL BE ABOUT $1800 FOR PARTS ,$500.00 Labor.Should pick up 405 hp gross 360 or so rwhp.My research indicates lifter,push rods,rocker arms,since they are rollers ,can be reused( UNLIKE FLAT TAPPETS) ,Need new head bolts etc but thats in the cost.Now compare the gains and costs compared to a new exhaust at $600.00 or so and a CAI for a FEW BUCKS(with almost no HP gain )Also,spoke to Diablo today and their # 193 predator for the Ls1&lS6 WILL UPDATE TO ZO6 SPECS,that is the fuel,ignition maps and the fuel cut can be increased.Stock GTO Throttle body& MAF are compatible ( Zo6 MAF is good for 3 hp and not worth the $260,00...Keep in mind we have the Ls6 Block and intake.In my view this is an excellent compromise,really good HP gain,retain excellent reliability,good fuel mileage ,keep the excellent stock ehaust( same headers as the Zo6 vette),stock cold air intake,at a cost of about $40.00 per HP.I am not a drag racer ,just want something a little different but with good reliabilty etc.Seems to be a sensible approach.GM says the typical engine design considers 125,000 miles as the reliabilty bench mark so the Vette LS6 ZO6 parts bin looks pretty good.

You guessed it,the parts are on order.Going to Dyno this week to establish a base line but the Predators on back order for 2 weeks and will not start till I have it

Your thoughts and comments are welcome
Why not the CNC ported LS6 heads from GM? They'll support up to 500 HP.
 

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$1300 for 55 hp sounds pretty good.
but im interested in doing mods that will affect my warranty as little as possible. this is what im thinking about
Good intake with heat shield(like MPD): $300, 10-20hp gain
Spintech Exhaust: $599+$100 for installation(this is a guess), 20-30hp gain
Predator Tune: $450(prices vary slightly), 10-20hp
this adds up to gains of 40-70hp.
 

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Knight Errant
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We'll see soon I hope...

scheer said:
Not smog legal and might flunk the annual test
We'll see soon. I hope to find out. In any event GM says the LS6 heads are only smog legal on the Z06...(which I'm pretty sure is a load of crap). The more head work I did on my older cars, the better they passed.
 

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Discussion Starter #6
Old Goat said:
We'll see soon. I hope to find out. In any event GM says the LS6 heads are only smog legal on the Z06...(which I'm pretty sure is a load of crap). The more head work I did on my older cars, the better they passed.
I was told GM only applied for certification installed on the Vette,but with cats installed the GTO with LS6 mods I should be fine in my state If the Zo6 makes I will Our state requires a dyno run to simulate 5 MINUTE DRIVE HOT.It seems as always Calif is most of the probllemIf you have any ADDITIONAL INFO ITS APPREDIATED regarding this issue as it is a concern that we all need to consider as we make street mods
 

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Discussion Starter #7
GTOdriver7 said:
$1300 for 55 hp sounds pretty good.
but im interested in doing mods that will affect my warranty as little as possible. this is what im thinking about
Good intake with heat shield(like MPD): $300, 10-20hp gain
Spintech Exhaust: $599+$100 for installation(this is a guess), 20-30hp gain
Predator Tune: $450(prices vary slightly), 10-20hp
this adds up to gains of 40-70hp.

HAVE NOT SEEN ANY HARD DYNO NUMBERS THAT SUPPORT YOUR HP NUMBERS FOR A CAI & CAT BACK EXHAUST SWAP ON THE GTO.On the street its hard to beat the stock setup under normal heat conditions.I do agree with the predator numbers however.
 

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Knight Errant
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Mass. tests

scheer said:
I was told GM only applied for certification installed on the Vette,but with cats installed the GTO with LS6 mods I should be fine in my state If the Zo6 makes I will Our state requires a dyno run to simulate 5 MINUTE DRIVE HOT.It seems as always Calif is most of the probllemIf you have any ADDITIONAL INFO ITS APPREDIATED regarding this issue as it is a concern that we all need to consider as we make street mods
We are tested on the rollers too now.. takes about a half hour..;) I am certain the stock LS6 head will pass, and companion cam as well. GM's failing to certify it for other bodies is more about certification costs than anything else. The engine does not care what body it is in, and the enhanced computers and twin cats should handle it just fine. I will go for the CNC versions and maybe 'touch' them here and there. I'm sure they'll pass as well for myself. When I do, I'll post, but I'm confident no one has anything to fear from the stock LS6 head assemblies. Avoiding product liability issues has become a way of life in America. Seen on a M-18 Claymore Mine 'This side to enemy' Duh! and a small sticker 'Do not eat'. :sneaky:
 

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Knight Errant
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Good approach. If the mods are made by the dealer with GM parts will the warranty still be good?
 

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Knight Errant
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That's up to the individual Dealer

Big Kahuna said:
Good approach. If the mods are made by the dealer with GM parts will the warranty still be good?
The is no warranty on the parts from GM per se'. If you get them through, and a Dealer installs them, it is up to them to stand behind the parts and work. Seems 'tweaky' in today's world, but that is their thing. Cetain things from GM, Crate Motors, Transmissions, etc. are warrantied. Go figure. They are good parts if sometimes conservative, and I have a long history of buying and using them. In truth, they are the same parts in many cases, off the same production lines. :rolleyes:
 

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scheer said:
HAVE NOT SEEN ANY HARD DYNO NUMBERS THAT SUPPORT YOUR HP NUMBERS FOR A CAI & CAT BACK EXHAUST SWAP ON THE GTO.On the street its hard to beat the stock setup under normal heat conditions.I do agree with the predator numbers however.
dyno numbers for catback exhausts are in the new issue of high performance pontiac. check it out


i believe that LS1 speed or someone else posted a dyno test for their intake showing a gain of 10-15hp. but i will bet you any amount of money that a cone style intake with good heat shield box will net gains of ATLEAST 10-15hp.
 

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GTOdriver7 said:
$1300 for 55 hp sounds pretty good.
but im interested in doing mods that will affect my warranty as little as possible. this is what im thinking about
Good intake with heat shield(like MPD): $300, 10-20hp gain
Spintech Exhaust: $599+$100 for installation(this is a guess), 20-30hp gain
Predator Tune: $450(prices vary slightly), 10-20hp
this adds up to gains of 40-70hp.
Well, I don't have any data to dispute these claims, but in my limited experience I can say that I believe these numbers are overstated, especially for the intake and tune. I would give each a max of 10hp, on a good day.

Again, I admit, I don't have any data, only my personal experience and perception based on "feel", which is about as useful as "teats on a boar hog." But I'd bet dollars to doughnuts (settle down OG :D ) that the original poster's suggested mods would make a far more perceptable change.

For those of us without dynos, how the car "feels" makes all the difference.
 

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FLORIT said:
Well, I don't have any data to dispute these claims, but in my limited experience I can say that I believe these numbers are overstated, especially for the intake and tune. I would give each a max of 10hp, on a good day.

Again, I admit, I don't have any data, only my personal experience and perception based on "feel", which is about as useful as "teats on a boar hog." But I'd bet dollars to doughnuts (settle down OG :D ) that the original poster's suggested mods would make a far more perceptable change.

For those of us without dynos, how the car "feels" makes all the difference.
well i dont have any HARD data to back this up either. but i could have sworn that diablos website said that the gains will be about 10-20 hp for a tune.

the new HPP shows a gain of 30 with new spintech exhaust so i dont think that 10-20 is totatly unreasonable.

i am very positive that a good CAI with heat box would gain you ATLEAST 10.

i agree that the original posted mods would make significant power. but like i said. i am more concerned with keeping the warranty for the time being.
 

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Old Goat said:
Why not the CNC ported LS6 heads from GM? They'll support up to 500 HP.
What kinda cam you think would make those heads street-happy???
 

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gto_in_nc said:
What kinda cam you think would make those heads street-happy???
I'm putting this at the top of my wish list.

TR - 224/224 .561/.561 114 LSA 1700-6600 RPM Power Band. Excellent mid-range & high RPM power. Requires computer tuning on automatic transmission cars.
 

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kmav8tor said:
I'm putting this at the top of my wish list.

TR - 224/224 .561/.561 114 LSA 1700-6600 RPM Power Band. Excellent mid-range & high RPM power. Requires computer tuning on automatic transmission cars.
That is a very nice cam. You guys should take a look at LS1tech.com in the dyno section. You'll see what combos produce the numbers you are after.
 

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Knight Errant
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Springs

DANSLS1 said:
Ok OG - what exactly is this supposed to mean?
Dan
Valve Springs for one Dan, and their companion keepers and retainers are one of the LS6 versions. I just have not nailed down which by part number specifically. There were good and not so good. This is important for lift bind height. There are a couple of posts by another member alluding to a paint stripe observed on his which may be either an inspector's mark, or a color code for the springs. I have asked around on it but gotten different answers. There are a few other areas, like some (or all) of the parts in the rotating mass where we probably have the LS6 parts. Again, not specifically nailed down. We have the Corvette LS6 Intake, and some of us definitely have the Corvette LS6 coils, some may have the F-Body LS1 coils. The Helms alludes to the two being used. I now know we have the F-Body .500 lift cam, not the 320HP Service engine .479/.467 cam (at least mine does). There'll be more as soon as I can nail this stuff down, then post. It's important to know where you start before you build. I hate surprises, especuially bad ones... :sneaky:
 
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