lucky67

I'm getting ready to build a resto-rod and want to use a LS motor. The LS3/480 has 480 hp and 476 trq while the LS7 hsa 505 hp and 470 trq. The LS7 runs about about $7,000 more than the LS3/480. If anyone has driven a car with one these motors is there a big difference in the power and has the numbers been hiped on the LS3. $7,000 will go a long way on other parts. IF anyone can help please chime in.

BarryK

the HP difference isn't all that great and the torque is slightly more on the LS376/480 over the LS7 and as you mentioned $7,000 will buy a lot of additional parts. Plus, if you really need or want the higher HP of the LS7 you could go beyond that with the LS376 by just adding on a supercharger
The biggest advantage I can also think of is with the LS376/480 over the LS7 is not having to deal with the extra install hassles of the dry sump system.

Personally, i'd think no matter if the HP was 480 from the LS376/480 or 505 from the LS7 the biggest problem on both is actually getting the power down to the street. I know from posts from people like John McGraw that have built retromods with the LS motors (LS1 I think in a '59 & an LS2 in a '65) that those motors with less HP than either of your choices can easily put the car sideways in just about any gear at any speed so I'd imagine the difference of 25hp between the two motors is a but of a moot point.

Poorhousenext

Barry has covered the differences. The LS7 dry sump system cost ups the LS7 cost to point you can almost get 2 LS3s for same amount of money.

If you don't want the hassel of installing dry sump system, you can buy a kit that converts the LS7 to a wet sump.

You are also comparing LS7 505HP not to the standard LS3's 430HP, but to LS3 with a cam upgrade. You still have the option of installing a cam in the LS7 later on if you feel the need for more power and increase the HP spread to 80+.

I'll be honest with you about why I went with LS7 for my resto-mod 66 convertable. It's because GM want offer the LS7 in a convertable, and they also want offer it with an automatic in the coupe. I wanted a LS7 convertable and needed an automatic so I could drive it in any driving condition, so I decided I'd build my own.

Now since I'm being honest, I'll be real honest as the difference in HP or CI wasn't the real reason either, the real reason was the same as why people buy a Z06 over one of the standard C6 models. The 505 HP LS 7 powered Z06 cost sets you apart from the masses ...LOL

Having a 427 CI small block over a 376 CI small block gives you about the same advantage as the C2 BB guys hold over the C2 SB guys. Not just anyone can afford a Big Block.

Regardless of which one you decide to go with, like Barry said, you have to be able to get the power to the ground or a resto-mod with less HP could just kick your butt if they can do that. Also if your going to use any current side exhaust system or a 2 1/2" out the back exhaust, you will be wasting you money on either a LS3 or LS7 engine. Both need 3.0" exhaust system to flow them or you'll be losing a lot of their HP potential.

PS: I'm building one of each, LS7/A6 Convertable and LS3 376/480HP/A4 coupe. The coupe has flaired fenders so it will handle wider tires to help the less Hp engine get the power to the ground. Sort of backa$$wards...LOL

firstgear

I am getting ready to go down another resto-rod path and I am considering the LS3. GM does offer the LS7 with a wet sump option as a crate motor so it doesn't have to be a dry sump with the extra canister.

I am looking for options as I have time, the big issue to me is what goes on top of the motor, I am looking for that unique intake set up. Of course there is always the twin turbo option.


As far as tires, I am talking with SRIII about using the C6 Z06 rear end and tire set up. Mike thinks he can move the geometry inboard enough that with a C2 coupe that a mini tub would make it work just fine.....

I will be watching to see what others come up with in terms of engines and options....

david srour

My understanding is that the LS7's torque curve is such thats its power is delivered at higher rpm's. Low end torque is really what you feel, so the LS3 would have more seat of the pants power.
Anyone have any updates on the LSx 454? This should be the ultimate torque monster and neck snapper.
If going w/ dry sump it looks like a challnge to locate the large oil reservoir and insulate rest of car from its heat.

1coolC2

Excellent point.......You can compare them on price but you can't compare them on performance unless you perform similar mods. The LS7 with cam and appropriate tune will produce well over 600 HP and 560+ lbft of TRQ. The main difference is the cost of the two motors. That cost is a DIRECT reflection of the hardware used in them. The LS7 is equipped with titanium rods, better cylinder heads and a dry sump oiling system (which is easy to install, people make it sound WAY to hard!!). These parts are not standard on the LS7 to make it "cool", they are there for performance and durability (which is why they carried over to the LS9)...but they also cost money. The LS7 is also hand built at Wixom performance center and dyno tested before it leaves as compared to a "production" type assembled LS3 engine. It's like anything else, you pay more for the better product. If you don't need that kind of hardware, the LS3 is more motor than you will probably be able to use and is probably the right choice.

As stated in the posts above, these motors are tremendously powerful across a WIDE power curve. In a C2 with limited tire patch, excessive wheel spin/speed can be a real problem in any gear. I have a cammed/tuned LS7 and am running 285/18 Nitto 555 tires on the rear. You have to learn how to apply power and recognize the cars input back to you so you don't get yourself in trouble at 70-80 mph by blowing the hides off the back and end up cross ways looking at oncoming traffic I have lots of testing ahead to dial in the SRIII chassis and suspension/tire combo to optimize the power to the ground.

Bottom line...unless you plan to race the car, a stock LS2/LS3 provides excellent power, durability and economy that can make you grin from ear to ear and you can always toss on a supercharger. Consider cost, desired power level and real expectation of what you plan to do with the car. Keep in mind that the higher power levels will also require you to beef everything else up, which will really add to the price tag.........dual disc clutch, chrome moly drive and half shafts, stronger ring and pinion, upgraded transmission (they can destroy stock T56's) etc.......like they say, the real question is…….how fast can you afford to go!!
Good luck with your project and keep us posted!!

R/Jeff



P.S I like my LS7 because I didn't have to change the 427 emblems on the hood

firstgear

now that is the best reason I have heard YET!!!!

66BlueRdster

Take a look at the engine dyno charts for both engines at:

http://www.gmperformanceparts.com/Parts/showcase.jsp

It looks like the LS3/480 is peakier given its smaller displacement and hot cam, with the LS7 having a horsepower and torque advantage below 2700 rpms and having the ability to hold its horsepower and torque well after 5500 rpms. Eyeballing the dyno charts at 6000 rpm, the LS7 has 55 lb-ft more torque & 20 more hp. By 6500 rpm the LS7 has 65 lb-ft more torque and 50 more hp. Incredibly at 8000 rpm the LS7 still has the same torque and horsepower that the LS3/480 had at 6500 rpm. I guess this is how the Z06/LS7 can have a great 0-60mph time and do it all in first gear.

Net, it seems more displacement allows for a flatter torque and horsepower curve, allowing for more average horsepower & torque / area under the curve.

John McGraw

If you have not read the current issue of Hot Rod magazine, pick one up. They did a crate engine shoot-out with 8 different engines, including 3 from the LS family. They installed all 8 engines in the same Chevelle, and ran them at the strip. Even the lowly 5.3 turned in very low 12 second e.t.'s , the LS3 430 hp turned in 11.50's, and the LS7 turned in 10.70 e.t.'s. I wished they had tested the 480 hp version, but I would bet that it would have been well into the 10's. Every one of the LS engines, including the lowly 5.3, would launch the front tires into the air at the starting line! This is with a TH 400 trans. Given the 2X price delta between the LS7 and the LS3 480, I would probably opt for the LS3 on future builds. Either one will supply more power then you will ever be able to harness on the street!. My 400 hp LS2 is just flat scary on 245 tires, which are the largest tires that will fit under stock C2 wheelwells. Even my 59 with a LS1, and 50 hp less is pretty scary under full throttle.

Regards, John McGraw

lucky67

Thanks for the info. I'll probably go with the LS3 cause my goal is to fix a car I can drive and enjoy with plenty of power not a race car that limits the distance you can travel. Not that the LS7 would do that, I can spend the money on other things like air, wheels, etc.

63dreamer

I say go for the LS3. If you want more power you can supercharge it. Makes for a very cool motor and still less money than the LS7. Here is my LS2 with magnacharger.

vintagecorvette

I have the LS3 430hp crate engine. It is awsome.

I plan to build another in the next few months and will most likely go with the same LS3. It offers the best bang for the buck.

oWEN

C2Driver

That is one pretty car oWEN!!!

- Pat

C5Maverick

I have the LS376/480 in my 12 GS Vette. Dyno'd & tuned, but idle is rough and surges below 2500 rpm. Any suggestions in tune?

FLYNAVY30

super old thread....but to answer your question, I would recommend finding a better tuner. The cam in that LS376/480 isn't particularly aggressive. Did you get the motor with the ECU, or are you running the factory ECU in your '12 GS? Any decent LS turner should be able to get that car sorted in a few passes on the dyno and an hour of street driving.

vettebuyer6369

Answerng a post from 11 years ago. Start a new thread with your question.