Your opinions on LS swaps into ZHPs

[DeathTrap]

This has been on my mind for while, mainly out of curiosity and interest. How do you all feel about LS swaps into our beloved machines?

Does it ruin the character?
Make it more appealing?
Sacrilege?

Personally, ignoring all the BS internet opinions on LS swaps, I think it's a better engine than the S54 for this application.
Before I get stoned, let me explain.

The S54 is a maniacal, high strung, race motor that need a little more attention to detail than an M54. It revs to the moon and sounds like nothing else. I do enjoy the fact that it retains the BMW spirit, but I'm not a purist...

So let's make a mutt. The LS provides gobs of torque and a flat, predictable power band. It's reliable, sounds beastly, can make an asston of power, parts are cheap, etc.

The cost is probably close with a fully sorted S54 swap vs a complete LS swap for our chassis. (Probably should verify that first)

So why not??

[az3579]

Absolutely, yes. I'd say an LS motor is a much better swap than an S54, assuming you are willing to invest the time and money into it. It's not a cheap swap if you're paying someone else to do it. The S54 is much more straightforward to swap in and will cost less in the long run, but if the money isn't a factor, or you're doing it yourself and know how to fabricate what you need on your own, I think the LS is definitely a better choice. Cheaper parts and maintenance, makes more power, and bolt ons galore. Plus..... V8. Shouldn't have had to say anything more than that. :)

[rkneeshaw]

I dunno, seems like the chassis has you limited on power to some extent.

I mean with the TS and 330rwhp the car is a ton of fun but I REALLY wish I had an extra 1-2k RPM to string it out longer at the track before shifting all the time. I could change gearing but then you lose some acceleration.

Lets say you put an LS into it and gear it right. By then you're probably at power levels that require wider tires to be anything more than a cloud of smoke when you try to accelerate. And now you're limited, because I dont think you can really do wider than a 265 rear tire (in a sedan anyway) without getting into serious fender modifications, and even then a 265 wide tire is not very wide when you need to put down 400 angry horses (because I'm assuming you wouldn't swap in an LS just to put down 300 or less hp....)

I think all purity arguments aside, I like the idea of an S54 better because you get power up through 8k RPM. With an LS you get a lot of grunt but you only spin it to 6k RPM... less than the M54.

[DeathTrap]

I'm with you on that one. I probably would go with a tall rear end, but that would take the *some* of the fun out of the car. By the time you're done with second gear, you'll be in jail on most public roads, third gear on the highway would be nasty, fourth gear would be for the salt flats. The ZHP has long gears from the factory anyway so maybe it wouldn't be too far off? Some of the LS motors redline at 6500 which is not far from the stock redline. It seems like it would drive almost like a stock ZHP, that's been going to the gym.

I got bored and put the numbers into a transmission calculator. The speeds at the end of each gear are exactly the same:
Getrag 420g
2.93 diff for the LS
3.07 for the M54 ZHP
34766

I think it would drive exactly like the ZHP, with double the HP and torque.

An S54 with the stock E46 M3 final drive:
34767

Still exactly the same. Amazing what gearing can do.

Multiplying the torque by the respective gear ratios, the LS with 400 ft-lbs at the crank would put down about 5000 ft-lbs at the wheel in first gear
The S54 with 270 ft-lbs would do 4100 ft-lbs at the wheel.

Of course the LS would be faster due to more HP, but they really aren't too far off.

So now we're down to the high rpm screamer or torque monster? (Kind of how all engine arguments end up)