Choosing the right LS3 crate

[my70toys]

Hi Guys,
I'm getting ready to swap an LS3 w/6 spds Tremec tranny in my 70 Chevelle convertible. I'm looking to basically tour a couple hundred miles around the Pacific Coast roads every now an then, semi daily driver went need, so basically a street driving. I have no desire to track and race with it. Done that before and vehicle not really driverable on streets.

My questions to you guys is this. There are three LS3 version as you know, 430, 480, and 525. Big difference between hp and torque, Prices are not leaps and bounds different. Tranny I'm set with the TKO 6 spds. Which one is right for my application, more reliable, more streets manner? Are the Hot Cams on 480 going to be problem long distance drive, will it heat up and affect the Reliability? I heard the 525 is not to manner for daily street drive, is that true and why from your experience?

I'm willing to spend on either one. I'm a little confused on which one. Let me know your inputs and advice? And if you have this set up give me your experience on the pros and cons, or if you thinks there a better set for me? Thanks in Advance!

[69L48Z27]

I did the 480 crate with GM computer and harness. I think it has very good road manners, stays cool. I'm using a GTO radiator. I used a T56 from a 4th gen and LS7 GM clutch setup. Haven't had it slip at all yet. 3.73 rear gear.

Plenty of power, I think all three are OK. For some reason I gravitated to the 480. Maybe price, can't remeber. No regrets. The thing useless in 1st gear.

[andrewb70]

If you want perfect drivability, just get the 430 and save yourself some money. If you want more power later, you can always install a different cam. That's really the difference between the three engines: 430hp stock LS3 cam, 480hp GM hot cam, 525hp GM ASA cam. The ASA can has a nice lope, but still has good street manners, especially in a 6.2L. I have one installed in the 5.3L that I am putting together for my Cougar, and I am not worried about it.

The TKO 600 is a 5 speed...the T56 is a 6 speed.

Andrew

[Motown 454]

Check where the max torque is on the 525, I think its up in the higher rpm range than the other 2 are. That would make the others better down low where most street driving is done. I think it was Dale from Schwartz performance that mentioned it.

[ragz]

Ls3

430@5900rpm/424lb@4600rpm

480@5750rpm/475lb@4500rpm

525@6300/489lb@4400rpm

This info off of chev performance site. I don't see where the 525 is not a solid choice for street.
I went with 525 but not on the road yet for any real life info.

The expirience I have, is with a 2003 z06 vet .
LS6-405@6000/400lb@4800
Tremic 6 spd / 342 gears

This engine pulls from idle to Rev limit so the Rev limit on a 525 is 300 rpm higher for max hp but the max torque is 400 rpm less. These engines Rev fast so I think the 525 is a winner, but just my opinion.

[badazz81z28]

I thought the 525hp version had the LS7 heads. If you don't plan on tearing into it, I would get the 525 horse. If plans are to swap heads, swap cam, mod etc....I would look for the cheapest LS3, probably a wrecking pull

[Schwartz Performance]

You can't put an LS3 intake on LS7 heads.
Also it's just the cam change, nothing else.

-Dale

[Mkelcy]

I've got the LS376/480 with the GMPP ECU/harness in my '68 Camaro with a Viper T56 and a 4.11 rear. I had the ECU tuned to improve fuel economy and to address some very minor low speed drivability annoyances. The car put out 440 HP to the rear wheels on a Mustang dyno.

The car is great - I did a Veterans Day parade of about 2 miles at a walking pace with no issues (other than a tired left leg). The car goes like stink and still gets 23/24 MPG on the open road.

I've not driven either the 430 or 525 horse so can't make any comparisons, but I've very happy with the 480 HP version.

[Cdog]

I thought the 525hp version had the LS7 heads. If you don't plan on tearing into it, I would get the 525 horse. If plans are to swap heads, swap cam, mod etc....I would look for the cheapest LS3, probably a wrecking pull

LS7 heads will have valve interference issues since the valves are larger than the LS3. Someone makes a aftermarket LS7 type head to fit the smaller Ls3 bore. Only way to get a LS7 head on a LS3 is to bore and re sleeve the LS3 to LS7 bore size.


I’ve gone back and fourth on my LS build as well. In my opinion the two best choices are a 430 HP LS3 or the LSA. Either one is easily modified to to increase their output by 30%.


I’ll have a set of LS7 heads and a LS2 block for sale here real soon if any of you want to build from the ground up.

[andrewb70]

The ASA cam is known to have a super broad torque curve. I wouldn't hesitate running it on the street.

Andrew

[Rwolf15241]

I went with the 480 HP crate with the Free control package on Black Friday Sale, New Magnum T56 6 speed Ram 11" Power Grip HD clutch kit. 1986 El Camino

[my70toys]

Hey Guys, Thanks for your input and advice! At this moment I'm closer to choosing the 480 hp, with only $350-400 more for 50 hp, can't really beat that deal. I do like the lopping sound 480, sound more true to the BB 454. Its only seem right on Chevelle. I've listen to the 430 on Youtube, seem a bit quite, very tamp, bit to nice I think, Then on the other hand the 525 a bit too aggressive, might be noisier Convertible, also I might be inhaling a lot of gas at a stand still. Beside I think 430 might cost me more if I choose to add the Hot cam later. I'm not looking to swap anything into the crate, just swap and GO, hopefully it'll last a good 100K or so, by then I'll just swap another LS which ever they come up with later. Well, as it stand 480, But if anybody else have anymore input, I would like to listen.


The TKO 600 is a 5 speed...the T56 is a 6 speed.

Andrew

My bad Andrew, I was thinking TKO 600 stand for 6 spds and 500 was 5 spds, LOL, Got It T56

[martZ]

I started with the 480 hp crate and wanted more. The GM tech's on the Hot Rod Power Tour talked me into the ASA cam and associated ecu. I sold the old cam and ecu on ebay. It cost me $200 and an afternoon for the swap. It was a huge difference. No drivability issues what so ever. I've put 12K miles on it since. 3.70 gears with .63 OD T56 Magnum. This year will be my 4th Power Tour. I average between 20-23 mpg.

[Schwartz Performance]

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https://static1.pt-content.com/images/noimg.gif

If you look at the lower RPM's, the horsepower and torque isn't far off. It's only in the high range (over 4500) that things change.

Notice how the 525 dyno put out by Chevy starts out at 3000 rpm. That's because it's designed to be a race cam. Also notice the RPM at the end of the graph is less on the 525hp.
The lobe separation on the ASA cam (525hp) is 110*. The Hot cam (480hp) is 112*. LS engines like more lobe sep and they will run nicer.
The ASA cam has a rougher idle- https://sdparts.com/details/gm-performance-parts/88958770 - Scoggin Dickey even calls it a rough idle.

There is a bit of valve overlap at idle with the 110* separation, which means it can tend to "burn your eyes" like older cars do at idle speed. Valve overlap in OBD2 cars causes the oxygen sensors to get confused and lean out the engine a bit, which can cause some heat.
This of course is in more extreme cases- but is still a little apparent with ASA cams.

Jeff had an ASA cam in his Ultima GTR with an LS6 years back before the twin turbo LS2, and he didn't care for the driveability or the smell especially at idle and on the Hotrod Power Tour.


Now this isn't meant to scare off the 525hp owners or potential owners, just meant to be FYI. Obviously there have been success stories like Marty above me.

We prefer just swapping an LS7/9 cam in and calling it a day.. They put out 500+ with that cam. The lobe sep on those is really high which helps smooth out the idle a bit. Why GM doesn't do that instead is beyond me!

-Dale

[Trevor @ Texas Speed]

Another option would be to look at a custom-built turn-key engine that you can tailor to be as tame or as radical as you'd like! :) We offer multiple LS3 turn-key engines ranging from the standard 376 CID to a 418 and 427 CID stroker. You can view all of our LS3 turn-key engine packages at the link below:

http://www.texas-speed.com/c-2211-ls3-turn-key-engine-packages.aspx

Our 540 HP and 565 HP packages both use factory GM internals. These are meant to be more comparable to the GM crate engines that you're looking at. It helps save some money for the guys that aren't interested in forged internals. Both of these packages will use factory, unported LS3 cylinder heads and one of our TSP custom-grind camshafts. The lower HP packages of each engine size are built for stock-like, smooth idle while the higher HP package will have a little more compression and a larger camshaft. The 570 HP and 590 HP 376 CID LS3's use forged pistons and rods with a GM crank. All of our 418 CID and 427 CID strokers are built using forged crank, rods, and pistons, FYI.

All of our TSP turn-key engine packages will include a custom-tuned ECM with a custom-built engine harness. So, we can custom-tailor the harness for your setup. This is nice if you've ever used a GMPP engine controller kit. They supply so much extra length to every connector on that harness, so you spend days trimming it down to where it looks nice under the hood. If you decided to swap to a GM electronically-controlled auto trans, we can have the harness built to control the transmission, too. Lots of customization options with our packages! The LS3 540 HP and 565 HP packages are also the only two packages that do not have ported cylinder heads. All of our other turn-key engines will feature Precision Race Components ported cylinder heads. Ported cylinder heads are a nice power upgrade for you because they won't affect the streetability of the car whatsoever. All of that will be dictated in the cam and compression ratio. So, if you decided that you liked our 376 CID LS3 590 HP package but wanted a smaller cam with it for better driveability, we can make that change no problem for no extra cost! With the exception of our 540 HP and 565 HP LS3 packages, or turn-key packages will also include custom billet aluminum valve covers and a coil relocation kit to provide you with a cleaner look under the hood! Below is a link to a customer's 427 CID LS3 turn-key engine that has our valve covers, as well as the optional Precision Metalcraft sheet metal intake manifold installed:

https://www.facebook.com/307827879142/photos/a.443704869142.240628.307827879142/10152793013839143/?type=1&theater

Feel free to give us a call with any questions or concerns. All of our sales staff is very knowledgeable about all of our engine packages, so they will be able to assist you in selecting the correct setup for your wants and needs. We are here to help! :)

Thanks!

Trevor
Texas Speed & Performance