knox79

Looking at installing 427 into 04 c5 automatic this fall, I am trying to get an idea of what to be on the look out for when I get started. Will the computer be able to handle the adjustment or will that have to be replaced? Can you send it off to be reprogramed, any advise would be greatly appreciated.

~JOSHUA

iTrader: (92)

A small BOOK can be written attempting to cover the general questions you've asked.

The computer can handle the adjustment if you have the correct reluctor wheel on your crank (or a box to convert the signal from a gen4 to gen3)

Same for what block you decide... gen3 with internal knock sensors or gen4 with external and harness for relocation....

Yes you can send your computer to be reprogrammed, which will be needed anyway as I'm sure you'll have upgraded fuel injectors and at the least you'll need those calibrated for proper flow. ECS (East Coast Supercharging) has the lowest rates for sending your computer for them to mail-order-tune. $149+shipping.

Let's get real here. You aren't building this engine yourself obviously. Just ask these questions to the shop/engine builder who you are using. There are wayyyyyyyy too many variables at play when it comes to putting a 427 in a gen3 car.

99C5JA

For starters you need the the cam position and knock sensor extensions. You'll also need a 58x to 24x crank signal converter (LPE sells one). The throttlebody will also need a converter harness. The LS7 block will need some minor clearancing to fit the motor mounts. If you want to go wet sump you'll need to get the pump, pickup and the appropriate pan (I think an LS2/LS3 pan out of a C6 will work). I think there are some minor block modifications needed to go to a wet sump setup as well. Dry sump will be more complicated and require some under the hood component relocation.

Your 2004 PCM can handle a reprogram to run the LS7, however this needs to be done by a competent tuner on a dyno. A mail order tune is not what I would recommend. You will also need to substantially beef up the transmission in your '04. And you probably should get a stronger differential and halfshafts.

~JOSHUA

iTrader: (92)

^ like this is a serious thread.

I've got $1000 that wants to bet this thing never goes anyways past the OP's daydreams.

99C5JA

Don't think I'll take that bet

We all have dreams. To bad my wife enjoys squishing them like a cockroaches. But honey a 416 LS3 would be .... SQUISH

2slow2flurry-ous

iTrader: (13)

Damn, harsh but true. A guy that went to highschool with me had vengence do this conversion in his 02-03ish Z06. His name is Greg Brock, dunno if he's on this forum or not.

knox79

99c5ja
Thanks for the info, and Joshua thanks for encouragement.

NoTractionLS1

I would just go LS6 but hey thats just my 2 cents!

99C5JA

Spend all that time and money to swap the motor for 50hp? You could swap the heads to any aftermarket ported factory casting and a moderate cam and make a lot more power than an LS6 swap would net you. And it would be much easier to boot.

NoTractionLS1

Yeah but there is a better base for Mods and info out there for the LS6 tho. I think this subject is almost on the lines of the infamous LS6 vs LS2 threads. There pros and cons to every engine. It all comes down to how you wanna build your car and what are your ultimate goals. Just b/c you want a LS7 in your car doesn't mean its the right choice necessary for you.

Patrick G

iTrader: (14)

I tuned a friend's 2004 C5 that got a nasty 430ci LS7 with lots of LME goodies in it in 2007. It had been to 2 other tuners before it landed in my lap. To say it was a learning experience would be an understatement. The tune turned out great and the car made 600rwhp. He's put over 40k miles on the engine and it still surprises a lot of motorcycles. The undertaking was very involved and very expensive though. I'm sure the conversion cost has come down in the past 2 or 3 years but he had close to $20k in it when it was all said and done. New fuel system, new exhaust, new clutch/flywheel, new higher capacity radiator, new air box, all the wiring. Seriously, it's not just the engine you have to consider.

ysb02

For the all the effort required it may be the same price to just sell your c5 and pick up a c6 z06.

It'd be cheaper to just go with a blower to get the same power as a LS7.

99C5JA

A better base for mods? No. The differences between an LS1 and LS6 are negligible. There is no way the time and money necessary to swap in the LS6 is worth it. The key things that make the 50hp difference between the two, the heads and cam, are the first things you would change to make real power. The most inexpensive aftermarket stage 1.5 heads will outflow the LS6 heads and the mild "gentleman" cams will provide more power than the LS6 cam.

MPM IV

iTrader: (3)

I got the same attitude when I started researching and asked about cost.

It would be cheaper but there's no comparing the two.

Both true statements, but cheaper is rarely better. If the OP is looking at a crate LS7 the C6Z could be the better decision, unless he enjoys the modding process. I would recommend having one of the sponsors build a stronger motor which is the route I took.

GPG 02

Man, that's messed up.

ysb02

If he wanted to go your route with a built 427+ ci motor probably not.

A centrifugal sc kit would get near 600rwhp rather for ~6k not including trans cost. A pd blower would be a bit more and provide better low tq. I guess it depends what he wants to do with it. I'm assuming straight line stuff since it's an auto. Any way will require a built A4 which isn't cheap.

Pauls416Z

I installed a 416 LS3 in my 02 Z06. An LS7 would have cost me much more. I thought the LS7 couldn't go wet sump without changing the crank due to the crank whipping the oil into a nice foam, but it's been a long time since I had looked into it...

A better and probably cheaper solution would be a 408ci FI motor. Build it up right, using forged internals and run a modest amount of boost and 650+ rwhp is a piece of cake.

Good luck with your decision, I know there are a lot of choices..

ysb02

There's one guy on here running a LS2 based 402 w/ 541 rwhp 505 rwtq. Can you use the same headers on a LS2 going up from a LS1/LS6? I think the LS3/LS7 requires different ones?