High Compression S52

[MIKe30]

All my searching leads me to threads and post about going high compression and stroking mostly m50's, some m52's, and a few s50's - but i haven't seen much, if anything, about s52's.

I want to go as high of compression as i can reliably go. I'm assuming that's around 11.5:1, correct me if i'm wrong and let me know if I can go higher. Also please inform me of the best way to get there - is there head/block milling needed, custom gasket, pistons, just a certain combo or all three needed?

Also, I pulled the head off yesterday and found some scoring on 2 of my cylinders, still have #1 and #6 to check so maybe more. Does this mean the block needs to be honed? How much can safely be done? Does that mean new pistons?

I'm sorry if a lot of these questions have been answered, but I certainly searched and have not found anything for s52's. I believe cylinder spacing is different for s52's so I need to ask!

tia

-mike

[So Live]

Depending on how bad it is, you might have to bore it. Hone for sure. Bring it to a machine shop and see what they say. If it needs to be bored, youll need pistons. Pistons might not be a bad idea if you want a good solid high comp motor.

Check out Vac motorsports for pistons and any motor parts

[gobuffs]

Why do you want a high compression motor?

I believe you can get 1st and maybe 2nd overbore pistons for the S52.

[MIKe30]

Depending on how bad it is, you might have to bore it. Hone for sure. Bring it to a machine shop and see what they say. If it needs to be bored, youll need pistons. Pistons might not be a bad idea if you want a good solid high comp motor.

Check out Vac motorsports for pistons and any motor parts

Ideally I'd like to know exactly what direction i'm headed before taking it to a machine shop in order to avoid machining twice... I guess with the help of this thread and through more and more reading i'll have a plan for both scenarios (just hone needed or bore needed)

Why do you want a high compression motor?

I believe you can get 1st and maybe 2nd overbore pistons for the S52.

Because I prefer naturally aspirated motors and I CERTAINLY want north of 250whp - 260 is nice, but ideally at least 270whp out of this s52. I've read enough threads to know 270 is definately attainable and not unrealistic. up to almost 300 at the wheels is attainable, but those suckers need rebuilds very often. I want something streetable, even if i'll have no traction without slicks :)

[gobuffs]

Because I prefer naturally aspirated motors and I CERTAINLY want north of 250whp - 260 is nice, but ideally at least 270whp out of this s52. I've read enough threads to know 270 is definately attainable and not unrealistic. up to almost 300 at the wheels is attainable, but those suckers need rebuilds very often. I want something streetable, even if i'll have no traction without slicks :)

Just bumping the compression is not the way to do it. You need to take everything into consideration. IP motors put out about 270 and are at the top of power vs. reliability IMO. Any more than than and you need a Euro motor.

You are a power on paper kind of a guy right?

[e30polak]

An IP race engine has been completely built and run between 8-10k done properly. Even so they put down only 300whp more or less, and make no power till like 4 grand. They are meant for the track and not the streets, plus you have to run 96+ octane to achieve the full potential of the motor.

I thought I would go for a nice high compression motor w/ my s52, but it's more worth it to go s/c if you want more power with an NA feel.

[MIKe30]

Just bumping the compression is not the way to do it. You need to take everything into consideration. IP motors put out about 270 and are at the top of power vs. reliability IMO. Any more than than and you need a Euro motor.

You are a power on paper kind of a guy right?

Think I was getting a little over excited. But it does seem most people (not IP racers) are getting 250+ with cams, tune, and otherwise stock internals. I'd be happy with that, but if i do need to bore my block, then i'd up the compression a little bit. I don't see how I shouldn't expect more than the guys with stock internals except cams.

Still reading left and right... Please feel free to post any links or good reads.

Hoping someone that was in a similar situation chimes in.

[matt]

Just bumping the compression is not the way to do it. You need to take everything into consideration. IP motors put out about 270 and are at the top of power vs. reliability IMO. Any more than than and you need a Euro motor.

True. And they cost big money, and not many people have the tools, experience, and patience to build them.

An IP race engine has been completely built and run between 8-10k done properly. Even so they put down only 300whp more or less, and make no power till like 4 grand. They are meant for the track and not the streets, plus you have to run 96+ octane to achieve the full potential of the motor.

I thought I would go for a nice high compression motor w/ my s52, but it's more worth it to go s/c if you want more power with an NA feel.

8-10k buys a decent rebuilt prepared-lite motor. Nothing special. Basically a stock rebuild with cams. Not 270whp. The difference between 250whp (easy) and 300whp (very hard) is about $10k.

I'm not saying don't build your own motor, if you want to. But don't expect to put down big numbers by picking the right parts off a website and slapping them together.

Edit: And to answer your question, 11.5 is about it for a street motor on pump gas. 12:1 on race gas will give you more power, but you'll need race gas. The tune is a big part of the equation also, of course.

[e30s52]

why not just buy a euro s50?

[FredK]

^ haha. I think Mike B. is selling his S50B32, ready to drop into an E30, for $7K. It could make sense.

[gobuffs]

^ haha. I think Mike B. is selling his S50B32, ready to drop into an E30, for $7K. It could make sense.

good price for a Euro ready to drop in...Euro motored E30s will always be worth more than built up US motors no matter the power.

[MIKe30]

True. And they cost big money, and not many people have the tools, experience, and patience to build them.


8-10k buys a decent rebuilt prepared-lite motor. Nothing special. Basically a stock rebuild with cams. Not 270whp. The difference between 250whp (easy) and 300whp (very hard) is about $10k.

I'm not saying don't build your own motor, if you want to. But don't expect to put down big numbers by picking the right parts off a website and slapping them together.

Edit: And to answer your question, 11.5 is about it for a street motor on pump gas. 12:1 on race gas will give you more power, but you'll need race gas. The tune is a big part of the equation also, of course.

Firstly, thank you for the insight on the compression question. Car will be run on 93. I assume tuning it for 93 isn't an issue.

But, I still don't see it. When you look up dynos of cam'd s52's on bf.c there are almost all in the 250 to mid 260 whp range with all stock internals (again, with exception of cams), a good tune, and the usual bolt ons (headers, exhaust, pulleys, etc)... I don't think anybody is argueing that here... I'll link some threads if need be I don't mind. Maybe I'm not reading those threads correctly.

When adding some higher compression into the mix with proper tune, how can those numbers not go up? That is what i dont understand.

why not just buy a euro s50?

Because I already have an s52. Plan was originally keep it stock, one day move on to euro s50. Unfortunately, got fucked with my motor and have to dig into it. Seeing as 250 and 260+ for cam'd s52's is done all day long - I think thats plenty for my e30 and no need to go euro. And there is always the what if i run into the same problems when euro s50 is bought. no gaurantees unless you spend $$$$$$$$$$$$

[Van Westervelt]

Euro s50b32's dont put down that much more power stock, than a USs50/s52 with cams, bolt ons and exhaust. Either way, unless you want to mod a euro motor, you will have similar end results. And the nice part of US motors is that so many parts are shared with the m50's, so they are cheap and plentiful.

OP, are you stuck on the NA, or would you be willing to run SC?

[matt]

Sure more compression will be good for more power... but it doesn't perform miracles. Only engine builders (and crooked dyno operators) can do that.

Think of it this way (M20B25 vs M50B25TU)... Going from 8.8:1 to 10.5:1 is only good for about 40whp (in conjunction with a TON of other changes to increase mass flow and optimize engine management) so would you expect a similar compression bump to yield another 40whp on an already tuned up S52 with no other changes except tuning?

Again, sorry if I sound like I'm trying to discourage you, because I think you're on the right track. I just don't want you to be disappointed when you don't make 300whp.

[madjurgen]

Isnt the rule of thumb 10rwtq/1.0pt bump in compression all other things equal? Doesnt seem worth it on a street motor.