DaytonaTA

iTrader: (6)

I'm in the early stages of a full rotisserie resto-mod third gen project. I haven't lined up any of the drivetrain components yet, as I'm still brainstorming possibilities. The only thing I've established so far is that I want T56.

I'm trying to pack as much new technology as possible into the build and limit the number of compromises that I have to make. As such, I'd like to build a modern engine with moderately high HP (~600 crank HP) but also with as high as possible MPG (not because I think it will save the planet, but because it's hard to do).

To get there, I'm thinking about little incremental things like electric water pump and electric power steering. I'm also thinking if it's possible to build an all-aluminum 5.3 with functioning AFM and VVT...and also a couple of small turbo's to get the full-throttle HP.

I've built a couple gen I engines but I don't have much experience with Gen IV engines or power-adders so I'd like to get some feedback from those of you that are more experienced. Simple things like intake manifold and cylinder head compatibility aren't as clear to me as they once were.

I know that most high horsepower builds do away with the AFM and VVT, but I'm not planning on building a 7000 RPM motor. Can I get these to function well with the boost necessary to meet my HP goals? Does HP Tuners or EFI Live allow much tinkering with AFM and VVT (other than to disable all-together)? Can I do this with a stock LC9 longblock?

I'm also open to some out-of-the-box input, so please, suggest away. I'm not opposed to smaller engine if it can still meet the HP goals.

DaytonaTA

iTrader: (6)

Anyone? I didn't expect a shortage of opinions.

A.R. Shale Targa

iTrader: (2)

IIWM I'd pick the L33 engine, send the 243/799 heads to TEA for a simple stage one port job and stuff a Lingenfelter 2-3 cam in there w/trunion upgraded rockers. An LS6 intake stuffed with 10psi from a single Borg Warner S475. Your horse level would easily be surpassed and with the T56 and a 3.42 rear gear combo you could get near 30mpg without vvt or afm.
The real difficulty is keeping your loud-pedal in check......

KCS

iTrader: (20)

I've been contemplating something similar with a LC9 and a T70 turbo. I think the VVT would be fine to use in a performance application, and probably very helpful with a turbo, as long as the lobes and springs are on the mild side and not too aggressive. The AFM system, as far as I'm concerned, is barely worth it in a stock application, much less a performance application. The AFM lifters are reputable weak points.

You will be limited to using cathedral port style heads with the 5.3L engines. The bore size of the 5.3/4.8L engines are not compatible with the large valves that come in the Gen IV rectangle port heads, like the L92/LS3 and the LS7, so your options are limited. Fortunately, cathedral heads are cheap, they're proven to be very capable of big power, and they come in several different chamber sizes to better fine tune your compression ratio. You will have to use a cathedral style intake manifold, like from an LS6, LS2, or even the taller truck manifolds if you have the hood clearance.

There are some stickies in this subforum (yellow highlighted threads) with a lot of good basic information for people that are still learning the fundamentals of the Gen III/Gen IV engines (aka noobs). Check them out as they can be very detailed and answer a lot of your questions before wasting your money on unwise purchases.

trevmust

I wanna build an ls3, do i still have to take measurements on a new engine

DaytonaTA

iTrader: (6)

This sounds like a good suggestion. Do you know anyone with a similar setup that could vouch for the mileage numbers?

A.R. Shale Targa

iTrader: (2)

I get over thirty with my M6/3.42 combo as the freeway rpms are between 1300-1450. The Cd of the third gen F-bodies is pretty close to my C5 although a bit heavier. The key is to keep the 10:1 compression of the L33 stock and cam it small which is why I suggested the 207/220 LPE so it will have great reponse when driving/cruising and not in boost.