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M52 or S52 in an E30

B C

Asked by B C,

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M52 or S52  

9 members have voted

  1. 1. Which engine would be better for my E30?


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B C Apprentice

B C

Posted
Posted

I have always been a fan of the M52 as a 24v swap option because prices on S52 are on crack IMO but the extra displacement means more fast.

Either engine would be going in an E30 (my E30)

It will not be boosted.
It will have the basic bolt-ons (S52 cams on the M52, headers, tune, intake manifold etc.)

From what I see, the M52 usually make 215-225whp on a dynojet  and the S52 make 230-240whp with more low end torque.

One line of thought is that M52 blocks are abundant and cheap if another one needs to be sourced. They are also found in automatic verts that don't get pegged off the limiter regularly and may possibly have less wear for their given mileage (this is only theory).

On the other hand, you gotta take what you can get for power with an NA engine and the extra torque of the S52 would make a big difference when you are in the wrong gear.

I also live in the real world where money is a thing and the $1200 or more I save by doing an M52 could be spent on a rebuilt head, rebuilt vanos, and lots of other refresh items.

BUT, should I ever sell my car (I KNOW, I KNOW, I KNOW) everyone has a boner for an S52 car and will pay $55,000 for one all day  (+/- $45,000)

Is the M52 considerably better bang for the buck, or will I be filled with regret for not holding out on an extra 0.4L of displacement?

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i_love_cars Apprentice

i_love_cars

Posted
Posted

i had to vote for S52, but I couldn't help myself. If I'm gonna have a modified car, I like taking it to car places and having something more unique that will create conversation with people. I think the S52 swap ticks that box a lot more than an M52. I tried to be objective about it for your sake based on your situation as you have described it, but honestly if the difference here is $1000 or less, then the S52 is actually the real no-brainer option. It's faster, more unique, and will make the car worth significantly more than the difference in financial cost between the 2 motors. 

If money is an issue I will help you buy the motor and you can pay me back. 

It is faster and cheaper to do an M52 (faster because you can source one locally right now and you may need to save money for longer if you want an s52)....but I just think if you are going to do a swap, you should go all the way and do a proper S motor.

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straight6pwr Enthusiast

straight6pwr

Posted
Posted
2 hours ago, suspenceful said:

I know nothing about E30s or their market with non-factory motors in them.

$1000+ for a measly 20whp is not money well spent in my opinion.

PS: Put an N54 in it.

however, his car will be worth at least $1000 more in the end, if not double that. (if that is an important factor to him)

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i_love_cars Apprentice

i_love_cars

Posted
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16 minutes ago, straight6pwr said:

however, his car will be worth at least $1000 more in the end, if not double that. (if that is an important factor to him)

exactly. 

S52 is the way to go especially if a parts car with engine, harness, and trans can be sourced - they usually don't go for more than $3k which is well worth it. 

2 hours ago, suspenceful said:

I know nothing about E30s or their market with non-factory motors in them.

$1000+ for a measly 20whp is not money well spent in my opinion.

PS: Put an N54 in it.

$1000+ for 20 whp is not money well spent to you because you're used to turbo cars where 75 hp can be gained with a tune =P  In the world of 200hp NA motors, 20 whp is a lot especially across the entire power band. 

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KaiserRolls Collaborator

KaiserRolls

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Posted

Makes me wonder how many M52 cars with S52 cams have been sold as S52 cars and how many S52 engines have been sold with M52 cams. Are there any markings on the block?'id thin there would have to be a stamp

Yes and no. Heads I believe are all casted the same (?)

Block should have markings

If not the vin is a give away "WBSxxxx" is ///M and "WBAxxxx" is non ///M iirc

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B C Apprentice

B C

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Thats a nice find, Earl

Ive made offers on 2 cheap M3s but the sellers are holding them for other buyers.

My friend in high school was told his E30 325is had "an M engine" when he bought it, hopefully this seller isnt also that mental

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m42b32 Collaborator

m42b32

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I have never driven a swapped car so I can't comment on that part of it, but I think there is value in "doing it once" and getting the S52 right off the bat as they are only going to get more expensive. No matter what you do with the M52 it will always be a little bit short of the S52 (unless you do an M54 rotating assembly), so if your goal is maximizing performance from an NA 24v, might as well get the S52 now versus wanting one later. If you can find a wrecked M3 for a reasonable price and have the time/space to take it apart, you can keep the S52/zf combo, part out the rest and end up with a decent deal on a motor/trans. 

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