[paint guy]

I need opinions (good, bad or indifferent) with my tentative plan. Here's the situation: 1969 GTO vert with a 71 YS, rebuilt to about 350 HP, 400+ ft-lbs with a 2801 cam, about 8.5 :1, HS roller rockers, etc. Behind it is a rebuilt T-400 and an almost-stock converter. Both have less than 5000 miles and neither have given me the slightest bit of trouble. With 3.23 gears, I would guess I am getting somewhere around 15MPG (mostly hiway.) Really the only thing that bothers me about the set-up is spinning 3 grand at about 70MPH, and the white puff of smoke after start-up when the car is warm ( I did not have the heads rebuilt). But after reading a couple of posts on here, the ls-3 type motor has me intrigued. GM has a "connect-and cruise" package with the motor, tranny, both modules, and gas pedal for around 10-11 grand with a rebate. With that and the fuel delivery, I figure 13K total. Since I figure a 220r4 or a gear vendors was in the picture anyway (3K) maybe a fuel injection set-up (another 2K) and I think I could probably get 4k for my motor and tranny as a complete unit, I'm only 4-6 grand away from having a dead-on reliable 430-480 HP, way lower maintenance, and better MPG to boot. During retirement ( a few years off) I will probably drive the car about 5000 miles a year or so. My goal is a combination if increasing performance (not sure why I want to do this but I do) and better drivability, lower maintenance. I realize there will never be a payback on gas saved vs money spent. I am also debating on the 430 Hp vs the 480Hp version for only $450 more. All opinions welcome.

[b-man]

I did my LS3 conversion on a 6-cylinder 1964 Tempest. Neat car, but somewhat limited in value as a collector car because of the 'non-GTO' pedigree.

A 1969 GTO convertible is a different story, it's a pretty valuable collector car especially when left 100% factory stock or pretty close to that. Something to consider, but not a deal-breaker. If it had a rare factory engine option I'd be a lot more hesitant to modify it.

There's more to the swap than meets the eye, but if you're up for it you should end up with a great road trip car that has more power than you'd probably ever need.

I envisioned doing the Hot Rod Power Tour when I finish my swap, not completed yet due to some difficult family issues plus the project snowballed into more than just a drivetrain swap. My car not only needed some restoration and repair work but I also decided that at the same time I would upgrade the entire suspension and braking system/wheel and tires. Nice to be able to quickly stop a car with 450+ HP and have it handle better too.

A good part of what motivated me in the first place was the entire package of excellent power and light weight combined with great fuel efficiency. The complete engine from EFI throttle body to pan complete with exhaust manifolds was $6200. I own a 2002 WS6 T/A so I'm very familiar with what the LS series engines have to offer in both performance and fuel economy, so the LS3 was an easy sell.

For the price it's hard to beat an all-aluminum V8 with OEM reliable fuel injection and excellent heads with 325 CFM intake ports that has simply incredible performance potential with some simple mods.

If the LS3 wasn't all-aluminum and just a bit over 400 pounds total I wouldn't have considered it. I was bitten by the Pro-Touring bug and wanted a better handling car so having a 600+ pound engine over the front axle wasn't what I wanted, as much as I love the traditional Pontiac V8 I also realized that this swap was a step in the right direction for my purposes.

I have a standard 430 HP LS3, I decided to keep the stock cam for better economy and smoothest running while in overdrive (4L70E auto trans with YANK 3600 lockup converter). It will run smoothly from 1500 RPM at 50 MPH while cruising in overdrive on the main road through my town, up to the 6200 RPM redline.

I read an article where a stock 430 HP LS3 was put on an engine dyno with only headers as a baseline. It cranked out 480+ HP with the simple addition of headers, it ended up putting out a best of 550 HP just by adding the headers and swapping cams and valve springs. Pretty impressive for 376 cubes.

Good luck with whatever you decide.

[paint guy]

Hello b-man and thanks for the reply. As you probably already know, my vert was the std 350 hp auto AC 3.23 open rear car when made. Original drivetrain is long gone. If I make the swap, there would be nothing preventing me or the next buyer to take it back to authentic (but not numbers matching) drivetrain anyway if so desired. ( But once an ls-3/4L70E is in, why would you?). My car is already modified, including 4-wheel disc, so stopping won't be an issue. The weight savings is definitely a plus. I will be running the stock manifolds, not headers. So one more question, if you will: its $450 to go from the stock 430 hp to a 480 hp with a factory-installed "hot cam" and springs. Still get the 2 year/50000 mile warranty. If drivability and street manners were a prime concern, would you opt for the extra hp? I assume the 430 hp version pushes your car down the road pretty well, right?

[b-man]

I would keep the stock cam for better street manners.

I think there are better cam choices than the factory 'hot cam', but of course with the warranty that seems like a decent option.

Personally I think the factory cam is plenty good for everyday driving and performance all rolled into one.

Are they offering exhaust manifolds that will fit the A-body chassis? The original manifolds that came on my LS3 were designed for the C6 Corvette and they wouldn't even come close to being useable unfortunately, the outlets would have run right into the upper A-arms and frame. A set of cast iron LS1 manifolds from an F-body can be made to work.

[paint guy]

Yours is a good question and I don't know the answer. The package is advertised as a direct drop-in for A-bodies (one dealer even replaces the oil pan with the correct one and does a few other things, this is referred to as their "swap-ready" package). Manifolds are included, just not sure if they will fit my GTO. a good question to ask. Thank you.

[b-man]

I might be interested in a set of those exhaust manifolds if it turns out they're made for the A-body chassis. The added ground clearance would be nice as compared to the headers I have now.

[paint guy]

I put in an e-mail to Pace performance to find out if the included manifolds will fit an A-body and will pass the info along as soon as I find out.

[Jerry H.]

One vote for leaving it Pure Pontiac powered. It's a 69 GTO Convertible. Now if you have everything else to go along with a 150-200k Pro touring type build, then go for it. But if you're just taking a fairly stock car then find a 69 Tempest sedan for your conversion and sell the GTO.

[Ron Landis]

is the shape of things to come. I used to be adamant about originality...but these power plants are amazing! I rode in Greg's Callaway Corvette...606 horsepower and 36 mpg. Ran 11.00 quarter with the top down...bone stock with a warranty no less! Anyway...like Troy Trepanier says..."If you want to build a nice car you have to start with a nice car. I'd go for it myself...but that's just me. I restored a '69 Red/Red four speed ragtop GTO using correct coded drivetrain and couldn't get my money back...so there's that. Had $35k in receipts and sold it for $25k.

[paint guy]

Ron, I remember when your car was for sale. the pictures showed a very nice car. Someone got a screaming deal at 25K.
I have also been very impressed witrh every car I ridden or drove with an ls powerplant. (even an ls-1). My car already is a LOOONG way from original. Can you tell which way I'm leaning?
Thanks for the opinions, guys. Anybody else want to chime in, whether you've done the swap, driven an ls powered car, are a stickler for originality, or anywhere in between, feel free.

[Jerry H.]

Originally Posted by Ron Landis

is the shape of things to come. I used to be adamant about originality...but these power plants are amazing! I rode in Greg's Callaway Corvette...606 horsepower and 36 mpg. Ran 11.00 quarter with the top down...bone stock with a warranty no less! Anyway...like Troy Trepanier says..."If you want to build a nice car you have to start with a nice car. I'd go for it myself...but that's just me. I restored a '69 Red/Red four speed ragtop GTO using correct coded drivetrain and couldn't get my money back...so there's that. Had $35k in receipts and sold it for $25k.

Sold that car at LEAST 15k too cheap. At least.

[Scarebird]

2010-14 Camaro LS3 exhaust manifolds should fit.

[b-man]

Wow, looks like it's already installed in an A-body chassis in that picture.

Very cool, shouldn't be too hard to find a pair from a Camaro that's been modified.

[fbrown]

I have the same engine, PCM, trans as B-Man. "LS3/4L70E into 68 Lemans" thread usually near the top of this forum. I would use the Holley oil pan as it is know to clear the tie-rod ends. At the time I did my swap the Holley pan was not available. I ended up raising my engine by about 3/8" for clearance. This caused the drive shaft angle to be marginal. I have had to car up to 80 mph for brief periods of time and have not had any vibration.

Over the years the 430HP Corvette has been dynoed by many different sources. I remember the ratings to range from 489 to 511 HP. This of course is in dyno trim with long tube headers, no alternator, ps pump etc.

There are many CAM choices that would be better than the HOT Cam, although all of the aftermarket cams would also require valve springs to be replaced. In a LS3 cam test "GM High Performance" a Lingenfelter cam had the same idle quality as the stock 430 cam, yet produced 540HP.

Everyone I talk to says the idle quality is compromised on the Hot cam and needs a low end gear and High stall to have good street manners.

I only have about 35 miles on my car and still have tune issues to sort out, but I can say the car moves out well even with the problems with the tune. (video in my thread - post #467). The tune is too rich.

Until I sort out the tune issues I can't say for certain, but for me a 3000 rpm stall seems too high, 1/2 throttle flashes the rpm and the tires go up in smoke. There seems to be no middle ground, either your acceleration is slow or you go up in smoke.

I have 3:42 rear with 245/50/16 tires.

To answer your question the connect and cruise gives you all new parts and should give you a very fast car with decent gas mileage.

BTW Hot Rod magazine had a crate engine test and the 430HP LS3 produced a 11.536 e.t. at 113.06 mph and with a little work got this down to 11.333 seconds at 114.23 mph. This engine as installed in a 69 Chevelle.

[andrewb70]

The GM package seems to be well sorted out.

I would go with the new Holley oil pan, as all other pans cause various problems. I would also look into the new Hooker cast manifolds if you don't want to use headers. The Hooker manifolds tuck up nicely against the engine and look a little nicer than the OEM parts. Although, I do believe that the ZL1 exhaust manifolds are stainless steel.

Andrew

[paint guy]

Thanks to all who responded, it is much appreciated. Fbrown, I have read your thread with great interest and I suspect in my very near future it will be of great assistance to me. My tentative plan is to purchase thru Gandrud Chevy, since they match the GM $500 rebate. This would put the package price for the 430HP ls-3/ 4L65E at $10300 delivered to my door. I am going to shy away from the 480Hp version to maintain better street manners. I will purchase the Holley oil pan, but am hoping the Camaro manifolds included will work without too much trouble.

[b-man]

Been doing a little research and found that the gen-5 Camaro manifolds most likely won't work.

Here's a single post from a thread on LS1Tech.com showing the interference. The exhaust outlet dumps pretty much straight into the rear lower control arm mount bracket on the frame, at least on the passenger side: http://ls1tech.com/forums/15843222-post10.html

Looks to me like a pair of Hooker cast exhaust manifolds are the best bet, made from High Silicon Ductile Iron: http://www.summitracing.com/search/p...aust-manifolds

Very reasonably priced at 307.95 with free shipping, about the same cost as the RARE Ram Air D-port 1967 GTO A-body exhaust manifolds I used to run on my car with the 455.

I plan to save some money and get the bare version rather than the ceramic coated ones, some POR-15 exhaust manifold grey paint is about one-fifth the cost and very durable. Most ceramic coatings on exhaust manifolds just end up disappointing you, they usually end up rusting within a year.

[b-man]

Just ordered a pair of the Hooker manifolds from Summit Racing. Was looking at both Jeg's and Summit and noticed Jeg's suddenly dropped their price down to $285.95. Summit beat Jeg's price by a dollar so they're now only $284.95 for the pair, bare cast.

This will help get my project back on track now.

I want the superior ground clearance of the manifolds instead of headers. The added performance of the headers just isn't worth the hassles and I plan to put a lot of miles on the Tempest in the coming years.