Increasing Coolant flow to Cylinders 4,5

90e34535i · Post by **90e34535i** » May 12, 2009 3:53 PM

From what I've read there is an issue with stock M30b35's coolant flow to cylinders 4,5 and 6.

Ive blown 2 stock head gaskets(with ARP studs), in the exact same spot, cylinder 5(and 4 was a little messed up too). Although cylinders 1-3 still have a great seal.

I was getting bad blow by, and assumed I had blown a ring land from the years of abuse, but after removing the head gasket and inspecting, it seems its just another blown head gasket .

What can I do with the Block still in the car, to increase cooling to the back cylinders, mainly #5?

JamesM3M5 · Post by **JamesM3M5** » May 12, 2009 4:46 PM

Might want to rethink the ARP studs. From research at TRM in Atlanta, standard ARP studs are only good as a stock replacement. They do not offer any additional clamping force. And in the case of the M50-based engines, the ARP 10mm standard studs offer 20-25% LESS clamping force than stock torque-to-yield head bolts! Might be similar issue with ARP studs. They make a new "ARP 2000" stud that requires nearly double the torque and offers much more clamping load.

You can also drill coolant passages in the head gasket to a slightly larger size to increase coolant flow in that area. Don't go too big.

turbodan · Post by **turbodan** » May 12, 2009 4:54 PM

Nothing wrong with ARP's. Clamping force is a matter of torque so it would depend on how you torque them, and there is such a thing as "too much". At some point you'll begin to distort the head and block and eventually you'll rip threads out.

Tensile strength is where head studs shine. Stock bolts are designed to stretch, and they will do just that when you start making lots of power. ARP or Raceware studs are required. They'll keep the head down, no doubt about that.

Post by **Shawn D.** » May 12, 2009 4:59 PM

JamesM3M5 wrote:Might want to rethink the ARP studs. From research at TRM in Atlanta, standard ARP studs are only good as a stock replacement.

TRM is not known as a "go-to" place on M30s, so I don't know that they have experience in that area. M20s, M50-based engines, etc., yes -- they are experts with them.

Bill in MN · Post by **Bill in MN** » May 12, 2009 5:01 PM

How 'bout insalling the b34 heater core outlet? This will get more coolant flow to that end of the head.

Martin in BellevueWA · Post by **Martin in BellevueWA** » May 12, 2009 5:08 PM

Check the deck surfaces of head & block with a machinist's straight edge?
Paul Burke drilled out the coolant passages on a head gasket for me. Also running a much better head, prep'd by Paul. My coolant issues seem to be over.

mooseheadm5 · Post by **mooseheadm5** » May 12, 2009 5:14 PM

turbodan wrote:Nothing wrong with ARP's. Clamping force is a matter of torque so it would depend on how you torque them,

This is only true if they do not yield. If they have the same yield strength as a stock bolt they will provide no more clamping force. I cannot say if they have the same yield point as a stock head bolt or not, only a tensile test machine can.
You are absolutely correct about there being such a thing as too much torque though. It is possible the OP has improperly torqued them. It is also possible that they cannot hold the power, as I have seen at least a few posts from various boards about people blowing head gaskets with ARP studs and boost, but that could be caused by many different factors including cooling, poor tune (detonation), poor surface prep, improper torque on bolts/studs, or QC problems with bolts/studs. Best thing to do if you don't like tearing down the motor often is to eliminate all possible causes when you rebuild.

JamesM3M5 · Post by **JamesM3M5** » May 12, 2009 5:21 PM

turbodan wrote:Nothing wrong with ARP's. Clamping force is a matter of torque so it would depend on how you torque them, and there is such a thing as "too much". At some point you'll begin to distort the head and block and eventually you'll rip threads out.

Tensile strength is where head studs shine. Stock bolts are designed to stretch, and they will do just that when you start making lots of power. ARP or Raceware studs are required. They'll keep the head down, no doubt about that.

Got a supercharged E34 M5 Touring 3.8L that has blown a new headgasket, also with ARP studs. I have not taken the head off, yet, but I believe the ARPs are not good enough for this application. The ARPs are necked down in the center. Clamping force is a product of tensile strength, cross-sectional area, and fastener preload. Even if the ARP head studs are made from a material with higher tensile strength, they may still ultimately not provide the clamping force at their prescribed torque level. The only way to find out is to directly test them against the factory bolt. Maybe Raceware studs are better in this case.

Stock M30 head bolts are not designed to stretch. They are angle-torqued at the final stage, but are not torque-to-yield like M20 and M50 head bolts.

JamesM3M5 · Post by **JamesM3M5** » May 12, 2009 5:23 PM

Shawn D. wrote:
JamesM3M5 wrote:Might want to rethink the ARP studs. From research at TRM in Atlanta, standard ARP studs are only good as a stock replacement.
TRM is not known as a "go-to" place on M30s, so I don't know that they have experience in that area. M20s, M50-based engines, etc., yes -- they are experts with them.

I brought up TRM since they actually took the time to test stock TTY M50 head bolts versus ARP supposedly "better" head studs. They measured less than 9000lbs clamping force on the ARP standard stud versus 10,500 on a factory TTY head bolt, size M10x1.5. This may be the same case on M12 head studs for the M30.

JamesM3M5 · Post by **JamesM3M5** » May 12, 2009 5:53 PM

Oh and I always upgrade cooling systems for FI cars. Factory-style drop in replacements are OK, but better solutions such as dual-pass radiators and high flow water pumps do much better than simply replacing the plastic-tank radiator with a similar aluminum end-tank unit. Speed of the water through the coolant fins is important, as is speed of the water in the engine block/head.

turbodan · Post by **turbodan** » May 12, 2009 6:15 PM

mooseheadm5 wrote:
turbodan wrote:Nothing wrong with ARP's. Clamping force is a matter of torque so it would depend on how you torque them,
This is only true if they do not yield.

You say that like the guys at ARP haven't made a name for themselves selling extremely high quality hardware.

JamesM3M5 wrote:Got a supercharged E34 M5 Touring 3.8L that has blown a new headgasket, also with ARP studs.

Thats been known to happen with forced induction. It usually has nothing to do with clamping force. If its not a failure of the gasket itself its the head heating up and softening. It can happen with or without detonation. I think concluding that the head studs in your situation caused the gasket failure would be premature and most likely incorrect. Feel free to contact ARP about the capabilities of thier hardware. They dont screw around with fasteners.

I definitely wouldn't go as far as to advise against studs in general. They're a known upgrade for the M20/M30, and I have a feeling they are for the M50 motors as well, regardless of the tangential and probably irrelevant conclusions reached by this shop in Atlanta.

JamesM3M5 · Post by **JamesM3M5** » May 12, 2009 7:22 PM

turbodan wrote:
mooseheadm5 wrote:
This is only true if they do not yield.
You say that like the guys at ARP haven't made a name for themselves selling extremely high quality hardware.

JamesM3M5 wrote:Got a supercharged E34 M5 Touring 3.8L that has blown a new headgasket, also with ARP studs.
Thats been known to happen with forced induction. It usually has nothing to do with clamping force. If its not a failure of the gasket itself its the head heating up and softening. It can happen with or without detonation. I think concluding that the head studs in your situation caused the gasket failure would be premature and most likely incorrect. Feel free to contact ARP about the capabilities of thier hardware. They dont screw around with fasteners.

I definitely wouldn't go as far as to advise against studs in general. They're a known upgrade for the M20/M30, and I have a feeling they are for the M50 motors as well, regardless of the tangential and probably irrelevant conclusions reached by this shop in Atlanta.

TRM co-developed new studs WITH ARP. They're the new "ARP2000" stud that are made from different steel, heat treated to give a more forgiving fastener, and torque up to an insane amount for just a 10mm fastener (32lbft then 2 90-deg stages). I've used the new ARP2000 on several different engine builds, all FI, for the M50. Looks like the old 12mm M30 stud needs a redesign if people are going to FI these engines. It's not the first time a known good company had had to redesign something, so why is it so hard to think that maybe these M30 studs aren't any better than factory bolts? The TRM guys proved that the old ARP M50 stud was worse - by 20% or more - than factory head bolts, and they worked with ARP to make something new for the booming FI crowd that's boosting M50-based engines to crazy levels for both street and road racing.

paul burke · Post by **paul burke** » May 12, 2009 7:38 PM

Its not about initial clamping force, its about maintaining clamping force during operation and retaining clamping force (preload) when the engine has cooled down. This is where the fastener comes in to play.
Has ARP spent the time to research M30 cylinder head expansion and contraction rates? Are they able to predict highest and lowest expansion areas in the cylinder head? I doubt they have ever had a M30 BMW head in house. Can't blame them , a lot of work and research for a very limited market.

The job of the fastener is to retain preload (clamping force) throughout the range of temp/expansion etc. As with the LS series Chevrolet the BMWs need two more fasteners per hole to distribute clamping loads more evenly across the deck and cylinder head surfaces.

By looking at water flow , and addressing areas that consistently have a higher running temps it is possible to "even up" the expansion loading of individual fasteners which will distribute loads more evenly across the mating surfaces.

Paul

paul burke · Post by **paul burke** » May 12, 2009 7:48 PM

JamesM3M5 wrote: Got a supercharged E34 M5 Touring 3.8L that has blown a new headgasket, also with ARP studs. I have not taken the head off, yet, but I believe the ARPs are not good enough for this application. The ARPs are necked down in the center. Clamping force is a product of tensile strength, cross-sectional area, and fastener preload. Even if the ARP head studs are made from a material with higher tensile strength, they may still ultimately not provide the clamping force at their prescribed torque level. The only way to find out is to directly test them against the factory bolt. Maybe Raceware studs are better in this case.

Stock M30 head bolts are not designed to stretch. They are angle-torqued at the final stage, but are not torque-to-yield like M20 and M50 head bolts.

ARP does not offer head studs for the S38, where did you get them?

Paul

mooseheadm5 · Post by **mooseheadm5** » May 12, 2009 8:43 PM

turbodan wrote:
mooseheadm5 wrote:
turbodan wrote:Nothing wrong with ARP's. Clamping force is a matter of torque so it would depend on how you torque them,
This is only true if they do not yield.
You say that like the guys at ARP haven't made a name for themselves selling extremely high quality hardware.

I did not imply anything about ARP fasteners, merely fasteners in general. If they a fastener is torqued to near yield strength, the torque is not proportional to the clamping force

You can see how the stress/strain curve is no longer directly proportional as you get close to the yield strength. Once again, I have not stuck an ARP stud in a tensile test machine or measured the elongation of one before and after torquing and running in, so I have no clue as to whether or not they are run past the elastic portion of the stress/strain curve (which, as Mr Burke points out, is what really matters- can they maintain clamping force after being run in.) So even if a fastener, such as a head stud made by some random company and not necessarily ARP, is not torqued to the elastic limit when installed properly, it may encounter that limit during use due to pressure, heat cycling, whatever, and lose the ability to maintain proper clamping force. When that happens, there is a problem.

turbodan wrote:They dont screw around with fasteners.

No pun intended?

paul burke · Post by **paul burke** » May 12, 2009 9:03 PM

mooseheadm5 wrote:
turbodan wrote:
mooseheadm5 wrote:
turbodan wrote:Nothing wrong with ARP's. Clamping force is a matter of torque so it would depend on how you torque them,
This is only true if they do not yield.
You say that like the guys at ARP haven't made a name for themselves selling extremely high quality hardware.
I did not imply anything about ARP fasteners, merely fasteners in general. If they a fastener is torqued to near yield strength, the torque is not proportional to the clamping force

You can see how the stress/strain curve is no longer directly proportional as you get close to the yield strength. Once again, I have not stuck an ARP stud in a tensile test machine or measured the elongation of one before and after torquing and running in, so I have no clue as to whether or not they are run past the elastic portion of the stress/strain curve (which, as Mr Burke points out, is what really matters- can they maintain clamping force after being run in.) So even if a fastener, such as a head stud made by some random company and not necessarily ARP, is not torqued to the elastic limit when installed properly, it may encounter that limit during use due to pressure, heat cycling, whatever, and lose the ability to maintain proper clamping force. When that happens, there is a problem.

turbodan wrote:They dont screw around with fasteners.
No pun intended?

Excellent post!
If you ever get a chance to conduct analysis on some of the fasteners out there it will scare you!

Paul

turbodan · Post by **turbodan** » May 12, 2009 9:59 PM

mooseheadm5 wrote: I did not imply anything about ARP fasteners, merely fasteners in general. If they a fastener is torqued to near yield strength, the torque is not proportional to the clamping force

The yield strength of my Racewares and probably ARP's too is so ridiculously high you dont really have to worry about that. For example, spec for my M20 studs is 42 ft-lbs. Per Raceware they would have to be torqued over 80 foot pounds just to begin to stretch. You would have to try to hurt them.

JamesM3M5 · Post by **JamesM3M5** » May 12, 2009 10:23 PM

paul burke wrote: ARP does not offer head studs for the S38, where did you get them?

VAC Motorsports lists an S38 set. Initially this engine was run with a Cometic .140" HG, but that left the motor flat with no midrange. The loss of compression combined with the poor compressor (don't buy an S38 supercharger "kit" from some dude in Austria) made for a crappy engine. I pulled the .140 gasket and installed a stock S38B38 gasket. It blew after about 2 hours of tuning on the dyno, but not before it made over 370RWHP on a Dyno Dynamics (more like 430 on a Dynojet) at a mere 4-5 psi. I don't relish the idea of having to do the HG again, and I'll take a second/third look at those studs before installing them again. Hell, I might even make it my mission to send them off to get tested.

JamesM3M5 · Post by **JamesM3M5** » May 12, 2009 10:37 PM

mooseheadm5 wrote: You can see how the stress/strain curve is no longer directly proportional as you get close to the yield strength. Once again, I have not stuck an ARP stud in a tensile test machine or measured the elongation of one before and after torquing and running in, so I have no clue as to whether or not they are run past the elastic portion of the stress/strain curve (which, as Mr Burke points out, is what really matters- can they maintain clamping force after being run in.) So even if a fastener, such as a head stud made by some random company and not necessarily ARP, is not torqued to the elastic limit when installed properly, it may encounter that limit during use due to pressure, heat cycling, whatever, and lose the ability to maintain proper clamping force. When that happens, there is a problem.

The new ARP2000 studs DO get torqued at least to the elastic limit, probably a bit beyond. They are not technically considered TTY, but you must measure them before, then re-measure if you intend on using them. ARP makes them in batches and has them ground to a precision length to make it easy to compare before and after.

Tensile strength is only one component of how much a fastener is able to clamp something down, so comparing UTS of fastener A vs B is rather pointless. The stock head bolt for the M30 is a Class 10.9, 145ksi UTS, .9xUTS = yield strength. Sure, you can make steel well over 180 or even 200ksi, but that alone does not make it a good choice. There are many times where more is not better. Class 12.9 hardware typically breaks under cyclical loading, where 10.9 hardware is more appropriate. Loading a fastener to the elastic limit, then keeping the cyclical load that the fastener endures lower than that elastic limit is what makes something last a long time.

mooseheadm5 · Post by **mooseheadm5** » May 12, 2009 10:43 PM

turbodan wrote:The yield strength of my Racewares and probably ARP's too is so ridiculously high you dont really have to worry about that. For example, spec for my M20 studs is 42 ft-lbs. Per Raceware they would have to be torqued over 80 foot pounds just to begin to stretch. You would have to try to hurt them.

The initial torque may not bring the fasteners to the yield point. Many things may cause them to lose clamping force. Permanent deforemation of the HG or the head itself are possible causes, as you have pointed out. Combustion pressure itself puts stress on the stud. The magnitude of the stress on each stud depends on the pressure distribution in the cylinder and cylinder head growth, among other things. It will not necessarily stress each stud equally. If the total stress (preload+combustion pressure+cylinder head growth, etc.) is high enough to reach the part of the curve past the proportional limit and into the plastic deformation zone, the fastener will deform.

mooseheadm5 · Post by **mooseheadm5** » May 12, 2009 10:53 PM

JamesM3M5 wrote: The new ARP2000 studs DO get torqued at least to the elastic limit, probably a bit beyond. They are not technically considered TTY, but you must measure them before, then re-measure if you intend on using them. ARP makes them in batches and has them ground to a precision length to make it easy to compare before and after.

And if the is actually designed to be torqued to yield, then it is designed to operate in a certain part of the curve. If it is not designed as a TTY fastener, then it will elongate once the total stress passes the proportional limit. And yes, you can make a fastener with a very high yield strength, but that fastener will be more brittle and can fracture rather than yield when a certain limit is reached.
Some steel alloys harden after yield rendering them stronger than before and make them more springy. That property is probably put to use in fasteners specifically designed as TTY.

paul burke · Post by **paul burke** » May 13, 2009 12:38 AM

JamesM3M5 wrote: VAC Motorsports lists an S38 set. Initially this engine was run with a Cometic .140" HG, but that left the motor flat with no midrange. The loss of compression combined with the poor compressor (don't buy an S38 supercharger "kit" from some dude in Austria) made for a crappy engine. I pulled the .140 gasket and installed a stock S38B38 gasket. It blew after about 2 hours of tuning on the dyno, but not before it made over 370RWHP on a Dyno Dynamics (more like 430 on a Dynojet) at a mere 4-5 psi. I don't relish the idea of having to do the HG again, and I'll take a second/third look at those studs before installing them again. Hell, I might even make it my mission to send them off to get tested.

Like I said ARP doesn't make head studs for the S38. VAC likes to use fasteners for other applications that "fit" BMWs when in reality the fastener was engineered for another application. In the case of the "S38 stud", last time I looked they were actually for a 2300 Ford Pinto.

Paul

paul burke · Post by **paul burke** » May 13, 2009 12:46 AM

JamesM3M5 wrote:Might want to rethink the ARP studs. From research at TRM in Atlanta, standard ARP studs are only good as a stock replacement.

Who/what is TRM in Atlanta?

Paul

mooseheadm5 · Post by **mooseheadm5** » May 13, 2009 1:06 AM

http://www.racersmarket.net/index.php?p ... &Itemid=93

90e34535i · Post by **90e34535i** » May 13, 2009 3:13 PM

Thanks everyone for all the responses.

I'm planning on buying forged pistons and connecting rods and rebuilding my engine, but would like to have it running and get it smog'd while I acquire the parts. If there's anything easy I can do to keep it together for a month or so it would be nice.

It sounds like the simplest thing I can do while leaving the block in the car for now, is opening up some of the coolant holes in a new head gasket.

Do you think opening up the back 3 cylinders small and Large coolant holes(driver/passenger side holes) each maybe 10-15% respectively would help to increase a little more flow in the back cylinders?

I don't want to make too drastic of a change and mess up the coolant flow.

cvillebimmer · Post by **cvillebimmer** » May 13, 2009 3:25 PM

Bill in MN wrote:How 'bout insalling the b34 heater core outlet? This will get more coolant flow to that end of the head.

Why don't you try this? I don't see any reason you couldn't tee into the return line from the heater core on your e34. It'll defintely get some more flow through to the rear.

90e34535i · Post by **90e34535i** » May 13, 2009 3:32 PM

I see the gooseneck fitting that hooks to the back of the b34 head. Do you think that would make a good deal of difference in regards to coolant flow to the back cylinders?

After looking at my old head gaskets, it looks like the back couple cylinders on the passenger side have full open coolant holes, while the driver side(where the coolant comes in) has all small holes. Maybe opening up a couple of the back driver side holes would help even the flow a little?

MyE28.com

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Increasing Coolant flow to Cylinders 4,5

Increasing Coolant flow to Cylinders 4,5