Jwright41

iTrader: (2)

Is there any difference to power between the two? I know that there is a little more in price for the 427 but is that really it? Goals are 500 - 550rwhp and a street machine more than a track car. Say that the top end is the same would the 427 need less of a big came to make 500+ than the 408? Just looking for some info.

redtan

iTrader: (5)

Kinda vague here? There are an almost infinite combinations of cam specs, heads, intake manifold, compression ratios etc. You can't just go by purely displacement.

You can have a 408 make significantly more power than a 427, and the same is true the other way around. Gonna have to give us more specifics about the builds.

All in all though, more displacement usually means more torque and a little more hp all else being equal. The LS3 based stroker also benefits from the larger bore, so that opens up more options for heads.

Jwright41

iTrader: (2)

Yea that is kinda vague. You did help answer one question I didnt mention - heads option. Guess I wanted to know if the extra $ for the LS3 would be worth it in the end for a build. Im kinda new to the big cubes and used to spending time in the LS1 part of this forum. My original setup was going to be a Procharger with TEA stage 2 heads and a blower cam from Tick on my stock LS1 but am considering staying N/A and weighing my options.

Floorman279

iTrader: (11)

Using the old formula, if u use same h c I in both motors, the 427 would make roughly 19 more hp

Grr

iTrader: (2)

LS3 is the better option for the sheer fact nobody wants to add 100lb to the front of their car. Plus the larger bore is great for a LS3 or LSA head.
The 427 with stock LS3 heads and a small cam will make 500+whp all day long

sergo

427. you won't have to go as radical for street duty.

Tainted

iTrader: (9)

yes.

Ls3 will have a larger bore and you have WAY better head options (small bore ls7 comes to mind )
It will be easier to make power, easier to drive, and theres no replacement for displacement.

if its your choice, and you get anything other than the ls3 im gonna smack you.

Jwright41

iTrader: (2)

Appreciate all of the info guy!!! Love the response from Tainted too!! Classic. So is there a conversion kit that is needed to get the LS3 where my LS1 used to be?

sscamaroburn02

iTrader: (14)

Here are some items you'll need for the conversion.

Here is a list of Lingenfelter parts that will allow you to swap an LS3 engine into a 1997-2002 Camaro or Firebird & 2004 Pontiac GTO. These parts could also be used for L76, LSA and LS9 installs.

GM LS3 crate engine PN 19201992

Lingenfelter part numbers
L480080000 (8) Uscar Injector connector kit LS2/LS7 with terminals & seals $26.80
L460065397 (1) TRG-001 LSX Engine 58x to 24x trigger wheel conversion module 254.95
CE-109103 (1) LS3 MAP sensor extension adapter harness 36.95

Available on Lingenfelter store
RXC5-KSRH (1) Racetronics LS2 to LS1 knock sensor extension adapter harness 29.95
UMI-EP-01111 (1) 90mm mechanical throttle body 549.95

You also will need a throttle cable bracket. We have several designs we are working on and will be offering these as a LPE part number soon.

Optional additional items
25318411 (1) GM 85mm LS2 MAF Sensor $169.95
CE-108100 MAF sensor adapter harness 30.95

Tuning software
EFI-FS2-T EFI Live V2 Scan and tune PCM programming hardware and software 799.95


Additional information
LS2 engines that have a 24x crank sensor trigger wheel the trigger conversion module is not required.
LS2 & LS7 use the same MAP sensor as the LS1/LS6 so no MAP sensor calibration changes are needed.
LS3 uses a different calibration MAP sensor that will require calibration changes.
This engine swap will require custom programming to your PCM.

KCS

iTrader: (20)

The problem is the long stroke on the 427ci LS3. It can cause a lot of wear on the skirts of the pistons or worse. An LS3 with a 4" stroke is still 416ci and more reliable in the long run.

That's not true. The same heads, cam, and intake will get you the same horsepower unless there is a huge difference in compression. Torque will jump with the larger engine, but any increase in power will be barely measurable.

george g

iTrader: (12)

You can get good reults out of a 408 with cncd ls3 heads and a medium sized cam.My 408 with the mods in my sig made 506hp & 465tq at 5,800 rpm due to junk valve springs floating and a clutch that was slipping.If everything was right it should have been close to 520hp at the wheels.

(SS)

iTrader: (1)

copy.paste

thank you

Jimbo1367

I'd go LS3 417. As mentioned earlier, longer than 4." stroke wears the skirts prematurely. Try a SEARCH with the username " Dietcoke " He has posted pics of his problems with a LS3 429

058mydust

If you get a block that was made for a longer stroke you won't have any issues. Read up... INFO

87silverbullet

iTrader: (11)

Yeah but guys not using a power adder really aren't going to spend that kinda dollars for just those few extra cubes. Most guys use ERL blocks with the aftermarket sleeves when they are slamming it with lots of boost or nitrous.

6D9 Matt

I plan on a 416... I think you should consider that, as many have said.