LS3 Engine Decision----which one?

[1965_SS]

I've got a 1965 Chevelle SS that I'm going to put an LS3 into. Car will be 85% street, 15% track time. It will have a T-56 Magnum. I will be rewiring the car with American Auto Wire, using Dakota Digital Gauges, Vintage Air setup, and a Vaporworx tank.

I'm looking at GM crate engines:
1. LS3 430HP for about $5900
2. LS3 480HP for about $6300
3. LS3 525HP for about $7300

Is it better to buy the higher HP engines and be done with it or buy the 430HP and do my own cam/spring swap on it? There is about a $1400 difference there.

If I did my own cam swap on the lower HP engine what is a good cam that would actually be better that the 525HP for $1400 or less. I've also read that there is a lower limit on cam lift/duration on these engines due to the pistons not having reliefs cut into them.

Are the GM controller kits any good or is it better to go with Speartech or something like that? The GM kits are about $1200.

Thanks for the help!

[Z06vette]

Hey Todd. I believe the best bang for the buck is buying the 430 engine, selecting a cam package that meets your needs (check out texas speed), using a custom built harness, and having the car tuned locally. However, that takes more time- changing the cam(but it will outperform the 525), waiting on the harness to be built (but it can be tailored to your needs), and finding a good local tuner(may have to travel, and key word is good). You'll also need a DBW pedal ,and ECM. On the flip side, you can buy everything you need, ready to go, plug it in, and go.. in half the time with the GM package. It will cost more and leave a little power on the table, while paying more $. I just went thru all this. I was so close to buying the 525, then I found a very low mileage pullout and just went with it. If you dont mind doing the legwork and already have a good tuner that is local, thats the route I would go. Either way I dont think you will be disappointed. Scott

[Vega$69]

I've done an LS7 with PSI harness and 2 GM crates a 480 in my buddy's car and my 525. Both with the GM harness. The harnesses are plug and play and included the pedal and sensors.

You can not get a custom harness, ECM, pedal sensors and Dyno tune for less then about 15-1600.

It's hard the beat the GM hot cams for power and drive ability Yes you can save a few bucks but may or may not get more power and may sacrifice drivability. If you buy the 430 you'll eat up most of the 1400 saved once you change the cam and tune. A bigger issue is you will lose the 24/5000 warranty.

Guys are seeing close to 550 on dynos with long tubes with the LS3/525 engines.

If your looking for more then 525 I would consider building an LS2 stroker with LS3 cnc'd heads or stepping up to an LS7. Either way you'll drop more $ into them then you will the GM crate motors.

[gnx7]

If you go on Corvetteforum.com there are a number of LS7's for sale (pullouts) for around $10K. A brand new one with ported heads etc zero miles for $11K. I know that is more than an LS3 cost... but you are getting 50 cubes+ and most of those have upgraded cams/springs, ported heads etc.

There is also one with 15K miles, ported heads/intake, cam, 570rwhp for $8500obo. It is a longblock so no intake.

I'm selling the oil pan adapters to make lines and run the dry sump tank either in the engine bay or trunk. You can buy a used dry sump tank off of eBay or RacingJunk for a couple hundred $'s. LS7 intake manifolds are around $250 or less (without TB or injectors). You can run LSA (56#) injectors and the rail is around $160 new or you can run Holley billet rails $120 and build them out from there.

I ran my LS7 with Holley HP Efi and a cable TB. I kept the dry sump. With only a cam upgrade and headers/tune it made 520rwhp/472rwtq and did 138mph in the 1/4. 3000lbs with driver. 50 cubic inches does wonders for torque in the low/mid range.

The main issues with LS7 motors is the valve guides wear out prematurely and the factory exhaust valve is prone to failure.... as long as those have been addressed it's a great motor.

[Vega$69]

Yep the LS7 is more $$$ and in stock form only 505 hp compared to the LS3/525

Also if you run LS7 you will need to either run the dry sump system which will cost a fair amount and find a place to put it. Or like I do on mine convert to wet sump (costs about $600 or so)

[XLexusTech]

How were the ls480 engines for power and street manners vegas?

[Vega$69]

How were the ls480 engines for power and street manners vegas?

I put the LS3/480 in a 69 with a TKO600 and 3.55 posi. 15" rally wheels

The car is super sweet to drive. Plenty of power and enough of a cam to sound great.

The LS3/525 is in my new protour car. T56 and 3.70s. You can tell a difference in the lope of the 110 lsa cam in the 525 over the 480.

Don't know if the 525 is really worth the extra $1000 but I did it because I wanted to see the diff between the 480 and 525.

Both engine are very street friendly. And traction challenged. Lol

[1965_SS]

Thanks everyone for the replies! I will be doing more research to see which way I want to go.

Vegas, how is that 525 as far as street manners go? I see your selling the Camaro that has it in it. Any video of that car idling, driving?

How would you compare your buddies 480 version to that?

[Vega$69]

Thanks everyone for the replies! I will be doing more research to see which way I want to go.

Vegas, how is that 525 as far as street manners go? I see your selling the Camaro that has it in it. Any video of that car idling, driving?

How would you compare your buddies 480 version to that?

I'll get some video up of both cars in a couple days.

It's hard to compare the two. His is a nice 69 with Hotchkiss Springs front/rear and sway bar. 15" Rally wheels with BFG TA Radials. Goal was to build the car to look perfectly stock until you open the hood.

Mine is full on protour.

I will say the 525 build pulls harder but part of it is due to the tranny and rear end gearing.

Can't go wrong with either one.

btw. Although mine is "For Sale" I really love the car and will probably keep it. Stupid me is I like to build and when a car's finished I get ants in my pants to start a new build.:idea:

[1965_SS]

You still need to tune those GM crate motors even if you use the GM harness, right?

Video would be awesome!

I like a lopey idle...........I had a big block with a Comp Cam [email protected], that was pretty radical.

[Vega$69]

You still need to tune those GM crate motors even if you use the GM harness, right?

Video would be awesome!

I like a lopey idle...........I had a big block with a Comp Cam [email protected], that was pretty radical.

The GM Performance Harness in both the 480 and 525 are plug and play. No tuning was needed on either one.

[gnx7]

Remember that HP is a measurement of torque over time.... so the LS7 would kick it in the nuts due to that alone (more torque). Add cam/headers to an LS7 and it will make 600hp+ with perfect driveability.

[Vega$69]

Remember that HP is a measurement of torque over time.... so the LS7 would kick it in the nuts due to that alone (more torque). Add cam/headers to an LS7 and it will make 600hp+ with perfect driveability.

The LS3 525 beats the stock LS7 across the board. Better HP and Torque

My 69 with the LS3/525 pulls my Corvette ZO6

Change the cam in the LS7 and 620-650 hp and 550 torque are easy #s to achieve and still very street friendly.

My last 69 I used an LS7 with a Texas Speed cam and ran 505 rear wheel at only 6200. Car was a beast. However my LS3/525 is also killer setup.

I just bought another LS7 for my kids build. Of course will do a cam change and convert to wet sump. Funny part is that just yesterday we started talking about selling the LS7 and buying a LS3/525. The money saved would pay for a lot of other stuff.

[markaaron80]

id go 430hp and contact Brian Tooley and pick a cam from the Hot Rod mag issue. picked up over 80hp from the 480hp crate engine with just a cam swap. ended up with 575hp max but very tight piston to valve .003
http://www.superchevy.com/how-to/engines-drivetrain/1404-three-cam-tests-on-an-ls3-engine-bumpstick-boomerang/

[Tom.A]

I went with the 430HP LS3. Got the car running and then did a cam swap.
HP exceeds the 295/35/18 tires very easy. However the cam swap that I used does make car buck some what at low speeds but it is not a big issue and still does fine in traffic. It is 227/237 , 613/622 with 114 Lobe centers. Dyno numbers are very subjective but my car was 517HP / 497 TQ at the wheels through a 9" with 3.55 rear and a TKO600 with no other mods other than long tube headers. I feel it was a very generous day. Either way these LS engines are sneaky fast and start every time. They don't put out the same thump as a SBC can or BB does but way less drama on top of decent fuel mileage

[Vega$69]

id go 430hp and contact Brian Tooley and pick a cam from the Hot Rod mag issue. picked up over 80hp from the 480hp crate engine with just a cam swap. ended up with 575hp max but very tight piston to valve .003

430 and a call to BT will get you 550 with good driveablity and you'll save a few bucks over the 525 if you do the swap yourself. Adding the cost of tuning may wipe out and savings.

Downside is you lose the warranty.

[awr68]

All great info guys! I love real world experience! I'm wanting to change to a LS soon and this helps a lot!

[MOREHORSEPOWER]

I would just buy the 525!

1 If I buy a new crate engine I would keep the WARRANTY !!

2 HP cost money ! I may be wrong but how to you gain 45 hp with just a cam swap alone in this engine ? If it started with the same platform as the 430 hp engine that is a gain of 95 hp .

3 When i was younger I was told a HP would cost $100 per HP . Today's money would more like $400 per HP.

[Vega$69]

The 430 is a smog motor. To meet epa standards the exhaust side gets choked down among other things

Swap cams and badabing you get big power and great drivability.

[randy]

i went with the 480hp version. Should fire up within 2 weeks. Might be next week. I wanted a little extra kick now and then in the future i will upgrade it. Nice learning curve and then tweaking everything else

[Firebirdsteve]

I went with the 525. Wouldn't change a thing.

[markaaron80]

I would just buy the 525!

1 If I buy a new crate engine I would keep the WARRANTY !!

2 HP cost money ! I may be wrong but how to you gain 45 hp with just a cam swap alone in this engine ? If it started with the same platform as the 430 hp engine that is a gain of 95 hp .

3 When i was younger I was told a HP would cost $100 per HP . Today's money would more like $400 per HP.


http://www.superchevy.com/how-to/engines-drivetrain/1404-three-cam-tests-on-an-ls3-engine-bumpstick-boomerang/



http://www.hotrod.com/features/1507-20-ls1-intake-manifolds-tested/

[1965_SS]

I ended up with a GM crate 525HP.
:thankyou:

[Firebirdsteve]

You wont be disappointed!!!

[Jay Hilliard]

I ended up with a GM crate 525HP.
:thankyou:

Good choice and due to ASA cam LSA, it sounds nice at idle also.