torque/power max fpr S50B32 (rods) and what head gasket?

[mr10ger]

hey there!

my brothers currently running a supercharged S50B32 (EURO!) which is completely stock. its pulling well over 500 HP (crank) at the moment but we and the ECU guy are afraid that the head may be lifting. so he considered changing the head bolts bolt by bolt for ARPs and as the VANOS has to be removed for that, he would renew the seals, anti rattle kit and so on.

so now were thinking about why not change rods and bearings, too. the point is, theres no money left for pistons. but in the future, were looking for more power an thus we need to lower compression sooner or later.

now the question is: should we just change to ARPs, get the vanos done and change rod bearings+ARPs (we changed them once but we used old bolts again, so were not feeling good about that...) and hope that the rods will handle the power? or should we change rods yet?

any experiences about how much power/torque the OEM S50B32 rods can handle?

also: if we change rods, we need to take of the head, so we will need a new head gasket too. any experience on MLS gaskets on that engine? we dont really want to use athena cut ring gasket because its tricky to reuse the head once a cutring gasket was used. and prices for new heads have risen extremely recently. next good thing with MLS would be, that we could use a thicker on to lower compression this way.


thanks so far for every idea!

[gdavid]

It is quite the jump to go from changing the head bolts to changing the connecting rods. Even if you pull the head, there is at of additional effort to drop the subframe, oil pan and pull the pistons out. If you are certain that the head has been lifting, the head gasket should be changed. You will see a number of opinions on here, but here is mine:
Since you are not ready to change the pistons at this point and may do it at a later point, there is no sense in replacing the rods now, just wait and do pistons and rods together to minimize labor and the number of part combinations that have been put together. Similarly, use a MLS gasket and for now and consider a cutring for the next time the motor is pulled apart. ARP studs no matter what.

I have torn down an engine from a wrecked car that turned out to have a warped head and a MLS head gasket, I took the head in to a machine shop measurement and it was warped beyond what could be resurfaced which suggests to me that prior to the accident this engine was overheated and warped the head, then it was reassembled with a MLS which was able to hold together even with a horribly warped head up until the car was wrecked. I do not know how long the car ran between the engine repair and the wreck, but if a head warped beyond repair can be sealed to a block with an MLS gasket, it speaks highly of the gasket capability.

[someguy2800]

With a supercharger I wouldn't bother with rods or pistons. I don't think it will ever make enough torque to hurt anything. I would put a new stock gasket in it with arp head studs.

[mr10ger]

We're talking about a charger that is capable over 700hp. At the moment, torque was quite low, lower than i expected, 500Nm. You have to transform it to lbs/ft yourself :P
Thats less than my M52 could handle so yeah i dont think we would have had trouble at this stage.
But you have to keep in mind that we're able to push (almost) full throttle for several minutes on the autobahn. Many power figures that are said to be not critical in US forums kill our engines within months or weeks over here. Because i was worried with torque levels over 550 Nm and the ECU guy too, we have gotten a good offer for a complete block rebuild with forged rods and pistons, so were going for it.

Long story short:
Current torque/power: 500 Nm 540 bhp on stock block with 0.65 bar (approx 8-9 psi?)
Next step over the winter: forged internals, new bearings, renewed vanos, 1 bar (14psi) approx. Steady 650HP+ on long term.
S50s are too expensive to take risks that are unnecessary.

Thanks for your help anyway

[328iFun]

Get a US block shipped to your door


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[milKt]

We're talking about a charger that is capable over 700hp. At the moment, torque was quite low, lower than i expected, 500Nm. You have to transform it to lbs/ft yourself :P, 1 bar (14psi) approx. Steady 650HP+ on long term.


Thanks for your help anyway

Describe "charger" please.
Please provide pics.

14 PSI on a turbo might do damage,
but supercharger torque is like a mosquito...unless it's a positive displacement twinscrew.

[rajicase]

but supercharger torque is like a mosquito...

LOL I love you

[mr10ger]

sorry for the long pause. its a rotrex C38-91 which is gonna be almost maxed out at the next stage. should do around 650hp then. not something i would want to drive stock block on an engine that costs well over 3500 euro in unknown condition.
so no twinscrew, but centrifugal.