C6LSx

I could use some help or advise from some of the technical experts that are Forum Members.

I have a 2008 C6 LS3 automatic and I have been considering some various different options for adding reliable horsepower and torque for my LS3 that is a warm weather daily driver.

My LS3 is not drag raced or driven hard and I have looked at various power adding options such as FI, cam and ported heads etc.

It's very important to me that when I have the engine "cracked" that any modifications provide extreme reliability for driving.

I also know that the old saying that there's "no replacement for displacement" holds alot of truth and with that said; I have been giving some consideration to a 427 Forged Stroker kit for my 436 BHP LS3.

I saw a 427 LS3 Forged short block that is available from Scoggins Dickey for approximately $5000.

In addition; I've also seen some offerings from some various vendors for just the forged 427 rotating assembly without the block that started at approximately $2500.00

My questions are the following:


1. By upgrading to a 427 forged rotating assembly and maintaining my same street LS3 street cam, heads and intake; what kind of realistic horsepower and torque would I be looking at?

2. If I was to purchase a quality forged 427 rotating assembly for my LS3; what specific crank, rods and pistons would you recommend?

3. Once I have purchased the forged 427 rotating assembly for my LS3; what type of realistic costs would I be looking at regarding a complete installation and tuning?

Thank you in advance for any help or suggestions regarding specific parts, costs and advice.

Vito.A

Just my opinion:
If you change the rotating assembly you absolutely should change the cam also. Your cam has some huge compromises in its design and you will not realize the potential of your 427 without changing the cam. In fact, you probably should change your cam even if you do not upgrade the rotating assembly. Look at the Comp Cams selector. They have some grinds that will act completely stock.
I prefer Callies cranks, either Oliver or Carrillo rods, and JE pistons. Stay away from the Chinese stuff like Eagle cranks and rods. The money saved will not help you a year later when you have a rod through the side of your block. Some will disagree and quote how well their Eagle parts have worked, but it is a gamble and I am not a gambler with my engines.

Check with some of the noted shops for installation. Try to find someone that will warranty their work and is reasonably close.

C6LSx

I so intend to make the additional investment in quality forged or billet components with regard to the crank, rods, wrist pins and pistons. I am not one to try and save a buck with cheap componentry and realize that you get what you pay for.

I have just begun to do my research and I am looking for someone to really help me by answering the specific questions that I outline in my posting.

One for example was what type of Callies crank ( e.g. Dragonslayer?), what type of rods and pistons etc, etc. I don't know the difference for example between H and I beam connecting rods.

I don't know for example whether I would be better served and save money by ordering a new LS3 block with all of the components pre-installed including a decent street cam versus just buying the whole rotating assembly and using my factory LS3 block

For example if I was to order an LS3 block with the rotating assembly preinstalled such as this from Scoggins Dickey; what would someone recommend that I upgrade in terms of the internals and finally what kind of costs would I be looking at to have in installed and out the door?:



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SpinMonster

You objectives for use and wish to use the stock 204 cam in a 427 indicate a strange dichotomy. On one hand you have the wish to improve performance without any compromise to reliability and on the other you are proposing a radical mating of parts that are expensive, involved to install, and not likely to exceed the performance of a simple cam swap in the very motor you have in the car.

I hate when people answer the questions they want to answer rather than the ones you are asking so the answers to your 3 questions are:

1- 475rwhp/490rwtq and a very short power band peaking very early in RPM.
2- I assume the block you are going to use is the 4.065 bore LS3 and therefore the rotating assembly would be the manley brand if they make a 4.1" stroke assembly fort that size stroke. The 427 would not be the configuration of the Z06 with a 4.125 bore and a 4" stroke nor would it have its ultimate HP capabilities.
3- Now this is the money question, quite literally. With machining, install, and tune, it will cost more than the purchase of an assembled shortblock and install and tune. I will state it will be 3000 to assemble the shortblock including machine work. The availablity of 416 stroker shortblocks including that of Lingenfeter makes the purchase of the rotating assembly (which you will pay 40% more than an engine builder would pay) not cost effective. Lingenfelter and Scoggins which you have already visited are around 5k for the shortblock (L92/LS3 block). Installation would be 2000 and a tune is 400-500 (add a lot in certain parts of the country such as the northeast where property taxes on a mechanic's home can be 12-20k/yr). The engine builder will not warranty the parts since he didnt source them for you and the installer will not warranty a shortblock he didnt build, and the tuner will not warranty the install he didnt do. To have all of the above done fromn a single tuner/builder would cost about 12k-15k and you get what you pay for. Forum tuners are good at what they do but they wont warranty other people's mistakes.

Now on to the question I want to answer that you didnt ask. What is your best course of action with cost and reliability weighed against performance?

A simple cam install with a 228 cam will net you 470rwhp and 450rwtq and will run perfect in your auto with a 700rpm idle. The stock heads remain untouched. Cost to install a cam on your car is 2500 tuned.

The stroker is a great idea if you want to cam it. 500-520rwhp is possible with your 427 configuration but is isnt going to like the idle needed to work in an A6. Personally I would do a 416 stoker since the 4.1" stroke isnt a good revving idea. A 416 shortblock is about 5k using your motor as a core could decrease that cost but it is better that you sell the stock motor and get a new shortblock payng the core outright. The net would likely be about 3000-3500 out of pocket once you sell the stock LS3. Install and tune is about 2500 from there.

C6LSx

Guy.....thank you so much for your help.

It appears that the 228 cam that you are recommending is going to be the most cost effective upgrade in terms of driveability, reliability and will provide the most effective return for dollars invested when weighed against the cost and labor of either a forged shortblock or rotating assembly.

I liked the idea of a forged rotating assembly for the added durability versus the OEM cast components, but I assume that the cam that you are recommending is within the operating parameters of the LS3 engine in a N/A environment.

I don't want to do anything silly like forced induction with cast internals and much prefer a N/A engine. So with that said; if the cam that you are recommending will not put any undue added stress on the cast internals, it seems to be the most cost effective option and will give me the biggest return for dollars invested.

With that said; can you please tell me exactly what brand and model cam I should look at purchasing. At one time; I was looking at the GM Hot Cam which I believe is rated at 219/228. I also looked at the Lingenfelter GT-11 cam as well but I am a bit lost given the technicalities of cam selection.

Very good idle quality, driveability and excellent torque and pull in the 1500-4500 RPM band is exactly what I am looking for.

In addition to the cam; what other components will I need...e.g upgraded valve train componentry for the stock cylinder heads?

Finally Guy; if I was to add to the cam CNC ported L92 cylinder heads, what would you recommend? There are the GM Performance CNC heads as well as the same heads from Lingenfelter with optional upgraded intake and exhaust valves, upgraded springs etc?

In possibly adding ported L92 heads to the cam equation; I would appreciate it if you could share with me the very best ported head option and what type of upgraded valvetrain such as the valves, springs, rockers, pushrods etc.

I don't want to overbuy what is not necessary regarding the cylinder heads but want to make sure that I purchase exactly what I need and the very best that is available for my specific application.

Finally; the last components to add to the cam and ported heads if you so recommend would be the following:

1. Ported TB and Intake

2. A very good quality set of LT catted headers. And again, there are LG's, Kooks, AR, etc. With regard to the headers; what would be your recommendation?

So ultimately by adding the following components what would you estimate my rwhp and torque to be based upon:

1. cam per your recommendation?

2. cam and ported heads per your recommendation?

3. cam/heads/ported TB and intake?

4. cam/heads/ported TB & intake/ specific LT headers per your recommendation?

Guy; thank you for taking the time to help me with this. Everyone seems to have an opinion on what is best, and that is fine; but I've followed many of your postings and you always present information in a very straightforward and logical way that makes sense, so I value your recommendation.

SpinMonster

You have a few misconceptions about some mods.

First, the stock internals have produced over 600rwhp on cars that are daily drivers and last as long as the people own the car and then get sold without issue. The application is what kills a car. Firged internals and cast alike can both grenade under track conditions. The power levels you are talking about with FI are not going to do anything to longevity. I have friends with over 100k miles on thier engines and still head to the track with nitrous. So in summary the stock bottom end is quite the performer.

Your questions:
1) A 228/232 114LSA no advance custom ground from comp cams on XER lobes. You seem to think that cam size/power is limited by the bottom end and it isnt true. The biggest cam you can get will not do anything to the bottom end other than make the car lope a bit and get worse mileage to a point.

2)No ported heads have produced any meaningful gains on the stock displacement unless you go really big on the cam which isnt for an A6. Gains of 6rwhp and a loss of 10rwtq have been had by 2000 dollar ported LS3 heads....its a loss in my book. Most people dont realize that a 260cc runner on a head is already big and 330cfm out of the box makes the heads pretty much performance even though they are stock. The same cam would work with ported heads.

3)Ported intake and TB: Cory Harris www.ls2portworks.com

4)LG headers worth every penny to me and I have had other headers on my car. I keep what works best and that is whats on my car.

Lastly, I have been in A6 cars with cams, N20, ect....the gears are a no-brainer. I have driven both 3.15's and 3.42's and the 3.42's are hands down the way to go. They do 1975rpms at 70mph and 2250 at 80mph. Ignore hype about the first gear non-sense. The 3.42's hook fine and if you get a cam and the gears, its a best bet. Corvettes of Westchester has done quite a few of them and I have never heard one whine or fail.

That should be your first mod. All the other power mods add power up high in rpm. Headers and gears make your LS3 A6 wake up and will also make you question opening the motor.

C6LSx

Guy.....thank you for your help. I sent you a PM regarding your recommendations and COW as well.

best regards - Pete

Gonjo9669

Went to check this corvette out last week, they claim it to be a 427 crate engine. Just want to confirm with more experienced eyes.?

SpinMonster

The throttle body for the crate motor would have been like the LS3 model (see below). That is a 90mm TB. That is a 2nd gen FAST 92 for the 90mm TB. Not sure if the gen 2 was available for the LS7. I've ported an enormous number of LS7 FAST intakes and they were FAST 102's so it says FAST 102 on it (see below). The FAST 92 has different intake runners for the LS2/3.

Why would you ditch a new TB that comes with the crate motor?:

old motorhead

You can buy an 427 "crate" engine and have little to no LS7 parts in it. Blueprint Engines PSLS4272CTFB: GM LS 427 ci EFI Retrofit Dress Crate Engine with Black Accessory Drive [530 HP, 495 FT.-LBS] - JEGS. Based off an LS3 with 4.125" stroke crankshaft. I think you can even get it with a cast iron block. Finding out which heads it has will tell the story.

SpinMonster

I agree that a 427 crate motor can be had as you say but the above is not an LS7 because it would have LS7 heads and a FAST 92 will not fit.

I don't get why someone would spring for such nice coil packs and valve covers yet cheap out on the FAST 92. A true LS7 crate would have come with new coil packs.