LS engine in a STS?

[wotmode]

I've been thinking, it seems like a lot of work and money to make substantial power improvements on N* engines. Now that GM has put a LS engine in a front drive, Would it be difficult to put an LS in a 2000 STS. Has anyone tried? Will the 4T80 bolt to a LS? Maybe I've taken too many hits from the bong, but the LS is easy to make big power with and force feed. Lots of programming available. Hardest part would be making the transmission work with a LS.(Would want to avoid the whimpy 4T65) This seems easier than spending 12k on a turbo N* that will have a "service engine soon" light on and might blow up an expensive motor (I've been reading Mark_99STS posts). The physical "making it fit" would be easy for me, I don't know who the "go to guy" would be for engine and trans. management. I do like the N*, but it would be nice to waffle stomp a new Honda Accord instead of edging it out.

[Ed Hall]

Yes the LS 5.3 engine is larger displacement so it would have more HP potential. If you wanted to do this conversion, it would probably be best to buy a wrecked Monte Carlo or Impala SS with this particular LS4 5.3. My guess is that this engine would mate up to the 4L80E but if it doesn't, just use the tranny from the donor car. Also worth checking out is the 6.0L that was offered in Chevy trucks. The only difference between this engine and the 5.3 is it's longer stroke. So it is physically the same size and has much larger displacement. Using this engine and modifying it to 600+ HP would really smoke any new Honda Accord. I have heard of other owners think of this conversion because of frustrations from N* head gaskets but have yet to hear of anyone doing this conversion yet. If you're into this kind of thing, this would be a neat conversion because you'll probably be the first Cadillac LS4 powered owner out there.

[Bruce Nunnally]

The 2004 CTS-V's are getting very reasonable, and come with a nice 5.7L LS6 engine.

[wotmode]

can a cts-v be made to ride nice?

[joeb]

come on now, don't let this thread wander from FWD to LS motors to RWD CTS-V's. people talk about how they stick FWD northstar motors in a RWD setup. supposedly the trans bellhousing pattern is similar for the NS to bolt up to a GM RWD trans. how is a LS motor supported in the engine compartment? do they use motor mount arms that bolt to the heads like with a NS? buick 3.8 motors use a motor mount that bolts to the front of the motor which is on the passenger side. so i would say the motor mount issue is probably an important issue. than how does the bellhousing line up? how about starter location? i always wondered why the NS trans has a bump out on the bottom for a starter?

[wotmode]

Yes the LS 5.3 engine is larger displacement so it would have more HP potential. If you wanted to do this conversion, it would probably be best to buy a wrecked Monte Carlo or Impala SS with this particular LS4 5.3. My guess is that this engine would mate up to the 4L80E but if it doesn't, just use the tranny from the donor car. Also worth checking out is the 6.0L that was offered in Chevy trucks. The only difference between this engine and the 5.3 is it's longer stroke. So it is physically the same size and has much larger displacement. Using this engine and modifying it to 600+ HP would really smoke any new Honda Accord. I have heard of other owners think of this conversion because of frustrations from N* head gaskets but have yet to hear of anyone doing this conversion yet. If you're into this kind of thing, this would be a neat conversion because you'll probably be the first Cadillac LS4 powered owner out there.

I work at a Chevy dealership. I've seen what happens to a 4t65 behind a 300hp 5.3L, so even more power would be a disaster. Once that block is fitted to the car, any of those engines will work, including new vette engines.

[Ed Hall]

can a cts-v be made to ride nice?

Yes.

Here how to do it:

1.) Get rid of the low profile tires and use 14" wheels and 205/75/14 tires

2.) Remove the rear sway bar

3.) Replace the front sway bars with a smaller diameter version from a 80's car.

By the way, I did the exact opposite on my 88 Eldorado. I installed low profile 18" tires, added a rear sway bar and installed a larger front sway bar from an Allante. The result is that it handles like it's on rails but the ride is harsh. I may go back to the original configuration since I now have an Allante which was tuned for super handling.

[wotmode]

can a cts-v be made to ride nice?

Yes.

Here how to do it:

1.) Get rid of the low profile tires and use 14" wheels and 205/75/14 tires

2.) Remove the rear sway bar

3.) Replace the front sway bars with a smaller diameter version from a 80's car.

By the way, I did the exact opposite on my 88 Eldorado. I installed low profile 18" tires, added a rear sway bar and installed a larger front sway bar from an Allante. The result is that it handles like it's on rails but the ride is harsh. I may go back to the original configuration since I now have an Allante which was tuned for super handling.

My 95STS had, in my opinion, a perfect balance between handeling and ride when equipped with 245/50/16 Mich. tires. I've driven the CTS-V, and it rides way too harsh for me. Maybe nonV springs/struts would work.

[Ed Hall]

Well, the CTS-V is using 18" tires which means a very low profile tire and little cushion between you and the road.

[wotmode]

come on now, don't let this thread wander from FWD to LS motors to RWD CTS-V's. people talk about how they stick FWD northstar motors in a RWD setup. supposedly the trans bellhousing pattern is similar for the NS to bolt up to a GM RWD trans. how is a LS motor supported in the engine compartment? do they use motor mount arms that bolt to the heads like with a NS? buick 3.8 motors use a motor mount that bolts to the front of the motor which is on the passenger side. so i would say the motor mount issue is probably an important issue. than how does the bellhousing line up? how about starter location? i always wondered why the NS trans has a bump out on the bottom for a starter?

I agree, lets keep this a FWD thread. Its nice to have lots of input on potential issues. I don't think motor mounts will be too bad. I'll get pictures of the next Impala I have on the hoist and get some measurements and pictures. I'm most concerned about engine to trans mating. Not just bell housing, but flywheel to torque converter also. If an adaptor plate is needed, the assembly might get too wide. I've got a 6.0L sitting in the garage and a tottaled 95 STS I might buy back from the insurance company.

[Ed Hall]

I'm most concerned about engine to trans mating. Not just bell housing, but flywheel to torque converter also. If an adaptor plate is needed, the assembly might get too wide. I've got a 6.0L sitting in the garage and a tottaled 95 STS I might buy back from the insurance company.

Good question on whether or not the 5.3/6.0 will bolt up to a 4T80e Cadillac transmission.

I did a search and came up with the following:

http://wiki.answers.com/Q/Will_a_4t80e_tra...to_a_3.8_engine

If that is true, then the bolt pattern is the same but you might have to modify the bell housing to accept the starter on the 5.3/6.0 if these engines have their starter bolted on the bottom of the block.

By the way, the Impala SS with the 5.3L engine uses a 4T65E transmission which is physically the same transmission as was used in the 80's FWD cars (4T60E). I wouldn't think you would have problems bolting up the flywheel to torque converter on a 4T80E transmission. Also since the 4T80E transmission is a larger more robust transmission, I also wouldn't think the bell housing would have any problems in terms of room to accept the flywheel from the 5.3.

Good luck..... I hope you are inspired to do this conversion. When the headgasket goes out on my 93 Allante, I might also want to do this conversion.

[Cadillac Jim]

If you want to do this, look at this motor:

<a href="http://worldcastings.com/prods_pages/101000.htm" target="_blank">http://worldcastings.com/prods_pages/101000.htm

</a>

Scroll down to the 101006A; it's all-aluminum. This is 520 hp, 495 lb-feet of torque, and 350 pounds -- 5 pounds less than a Northstar. It comes with a carburetor but Accel, Holley, or CHRFAB can set you up with DFI, if you can stand even more horsepower. It comes with a two-year warranty and a dyno sheet, broken in on the dyno and ready to run.

This would almost certainly require rebuilding the 4T80E with heavier gears, clutches and bands to take the torque, and I would work with World Castings to select the rebuilder and a different torque converter -- probably a beefed-up TH-700 torque converter to keep the lockup feature. An external transmission oil cooler with electric blower fans will likely be needed for best transmission reliability in hard use but the stock radiator tank transmission oil cooler is probably OK for street use, or even an occasional quarter mile run.

Summit Racing is a dealer for World Castings, Accel, Holley, and transmission rebuilders such as TCI and Hughes Racing that will talk to you about your 4T80E. You may need suspension and brake upgrades to deal with your new powertrain. When you are done, you will have the only normally aspirated 520++ hp Cadillac STS daily driver with a lockup torque converter out there.

Or, you can have Mosler Automotive in Florida put a second Northstar in the trunk. See Car and Driver article.He's done it with Eldorados but not with Sevilles, to my knowledge.

[wotmode]

....and visions of sugar plums danced in my head. That kind of power would be crazy. I love the idea of on demand rubber.

[joeb]

why not drop a LS motor in a newer STS? you need deep pockets to pickup a running STS and hotrod it. but common sense and hotroding have never been spoken in the same sentence. it would be nice to have the 92-97 body with a LS motor but it seems like the transaxle is the main issue. finding a nice FWD STS with a bad motor or trans is not hard and fairly cheap so the front end cost is low. its getting everything to work with the new motor that is the hard part.