LS3 verus LS7
 

Opinions please...
Looking at going to LS and was wondering what are some opinions between the two motors..Both are MAST, Black Label, only difference is LS3 versus LS7(besides dry sump)...I have always wanted a 427 motor, but is there any benefit to the LS7 versus the LS3 besides it just being a HP difference. Price is not the issue here, just wondering he benefit.

Yes it will be Driven on the road/city, Highway, and occasional Autocross when possible.


LS3 416 Black Label 630HP*

Type: LS3 6.8L
Displacement: 416 Cubic Inches
Compression Ratio: 11.2:1
Bore x Stroke: 4.070 x 4.000
Rev Limit: 7000 RPM
Crank: Callies Forged
Rods: Callies H-Beam
Pistons: Diamond 2618 Alloy
Cam: Mast Custom 3-Bolt Core Cam
Heads: Mast Black Label LS3 Heads
Intake: LS3 Car Intake
Valve Springs: Mast Dual
Part Number: 117-223

LS7 427 BLACK LABEL 675HP*

Type: LS7 7.0L
Displacement: 427 Cubic Inches
Compression Ratio: 11.4:1
Bore x Stroke: 4.125 x 4.000
Rev Limit: 7250 RPM
Crank: Callies Forged
Rods: Callies H-Beam
Pistons: Diamond 2618 Alloy Pistons
Cam: Mast 3-Bolt Core Cam
Heads: Mast LS7 305 Black Label Heads
Intake: FAST LS7 Intake
Valve Springs: Mast Premium Dual Springs
Part Number: 117-304

In another words, I don't want to kick myself for not going with the 427 when I should have..lol

I have a ls7 but,converted it to conventional oiling systems...less chance of oil leaks, no power advantage with the dry sump, easier oil changes etc. If price isn't a concern then get what you want...the ls7 plus it's more power lol

Thanks...I was leaning towards normal wet sump as you said less chances of leaks....

how about something completely different?
7.0L duramax diesel? cappable of ~700fwhp with stock air and fuel system, and more than double that with aftermark fuel/air systems.. ~5500rpm redline. and 35+mpg

weighs little more than a iron head BBC.. though they have an aluminum block coming out $$$$$$
http://www.socaldiesel.com/SoCal%20D...oker%20Kit.htm

the audi R18diesel as won the 24 lemans last 12? times?

I say LS7, 427. I'm going LS7, 427 myself with a wet sump. And $13k for diesel rotating assembly...that'll be a negative for me. May be a cool engine, but I'll pass. Lol!

but you will drop ~20k on an engine? sorry had too lol :poke:
http://www.mastmotorsports.com/view.php?id=155&c=4&s=6

FWIW
~20k will buy used dmax, rebuild (non 427 stroker kit), install and have 1000-1200hp with supporting fuel and air.
~7k can do a repower and be around 650-700

Go wet sump LS7 and get yourself that 427 you've always wanted. :thumbsup:

Marcus wished he "only" had 20k in his engine.
Comparing diesel torque numbers to LSX torque numbers is foolish. And those guys making those kind of HORSEPOWER numbers, Not TORQUE numbers, have pulled out a second mortgage on their farms. The supporting systems to make that happen is BIG MONEY, but I guess an 8 second diesel is cool...

RBuhr69, if money isn't a determining factor for you in this hand, I'd easily go with the LS7, no question. The Mast guys are the real deal. Damon has helped me out a ton, and they always go out of their way for you.

is it cheap..... NO.. none of this stuff is "cheap"..
1000hp diesel is darn near a you need A, B, C parts and a good tuner. engine, turbo, fuel parts can be had for ~20k labor not included

beating up on gas engines like audi does at the leman with a diesel is definitely cool and different..

i'd side with the LS7 over the LSx



got to pay to play right?

There is something special about a 427 for me. Katech converted my LS7 to wet sump, and added their Torquer 110 cam and CNC heads, dyno'd at 610hp, 570 ft lb. But people talk about the 'LS7 tax'...and it is real. Got to pay to play.

Attachment 48714

Wouldn't you be better off with a lsx427 than ls7 short block.much stronger

If boosting is in your future, then an iron 427 is the way to go. The weak link of an ls7 is the cylinder wall/ block support gets thinner, due to the larger bore size. I would not boost a stock GM ls7 block, but I'm not sure the OP wants to boost this engine.
Some of the early ls7's had valve issues, but that's not an issue with the mast black label heads.

Excellent feedback guys, I appreciate it......... all roads are pointing to LS7 as that is what I have always wanted. So its time to do the right thing and pony up for the LS7 versus the LS3 even though I know the LS3 will suffice. Now I wont worry about kicking myself and not getting what i wanted.

No boosting for me, straight up motor.......

thanks for all the input! :gitrdun:

We can build you a 427 with LS3 heads that will make the same power as the Mast LS7. It will be a dry sump though since that is the way we build them for durability reasons. I've been racing mine for 3 years and have never had any leak problems. We don't list any of our engine packages on our site but currently have a 600 hp, 650 hp package, and we are currently testing a 700+ hp package that will be going in my car shortly. Our horsepower numbers are with a mechanical water pump and accessories so they are real world as they would be in the car. PM me if you want more info. http://www.kurturbanperformance.com/

Kurt, I'm building an LS7 with LS3 heads because I'm using a Kenne Bell supercharger and that's what manifold it uses. But, as the OP stated, he isn't going to supercharge his engine. So, my question is, wht reason or why the LS3 heads instead of the LS7 heads on an LS7? Now, I do know, essentially that all 427's aren't LS7's, but I'm just curious as the OP stated he was leaning towards an LS7.

This isn't Kurt (I'm Tim) but I work with him daily. The reason for the LS3 heads is... there are far more intake manifold options out there for LS3 heads should someone want to run something different vs the vary limited choices for LS7 heads.

Thanks Tim. I now see your name "Tim" in your signature. Hahah!! I just wanted to know becuase I see alot of people using LS3 heads on 427. Can you pm me a cell or contact # so I can call you about some options?

Saw this thread good luck with you choice Im sure you will get a killer motor no matter which way you go.

check out our street and show series line up:
http://www.gashufferhotrods.com/category-s/1817.htm

We got both options for ya!:thumbsup:

Dasilva motorsport built a Z06 with a charger and a stock intake manifold, now it did have a cam swap and some head work but it put just shy of 1000 hp down at the wheels. They are the LS gurus lol. They're doing my motor for me I was told to expect 630-650 then got called a ***** for so little power lol