m62B44 engine rebuilding

[tptrsn]

Hey, I'm not shy, I'll throw my personal opinions out there! (some more, haha)

So anyway, my personal experience abusing a different factory stock engine with a turbo and water/methanol injection and an aggressive timing retard in boost demonstrated that normally you can do a LOT to a factory stock engine using those means to avoid detonation. In addition, I think your safety margin is higher with a centrifugal S/C setup because of the way the boost ramps in late and slow -- relatively speaking. So my opinion, FWIW, is that you should be pretty darn safe with an unopened engine at 12psi with water/meth injection, as long as you aren't running stock N/A timing up to 12psi? I can't remember off the top of my head how much timing retard was built into your tune?

For people wanting to be a bit more aggressive in the way their boost comes in earlier, more down toward peak torque or even before, it seems that compression reduction methods are prudent, and ring gap widening is probably mandatory. I did a little math today to sort of roughly figure out the resultant compression ratio with those 2mm shorter "de-compression rods" kenny1958 posted up, and I like the idea a lot.

Assuming 550cc swept volume per cylinder, 92mm bore diameter, and 10:1 initial compression ratio, I calculate that the resultant compression ratio with the 2mm shorter rods will be approximately 8.4:1.

To me that is an awesome compression ratio that affords a lot of safety for getting into some heavy boosting, especially when you figure in the fact that with these M6x engines we really don't have any aftermarket cams available to lower our dynamic compression ratios. My feeling is that with these rods, factory pistons, and factory rings with widened gaps, a guy would be good to go for some real fun...

Of course, for even cheaper cheapskates like me potentially if I get this far, I also pondered the option of just running a complete factory bottom end with widened ring gaps and simply getting some thicker head gaskets from Cometic. One thing I don't really have though is an accurate factory head gasket thickness, especially for the early M62s like mine. Anyone have one handy to throw some calipers on?

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I do have an early M62 engine sitting on a stand for mockup purposes, but I'm not exactly sure when I'm going to have it in my schedule to pop a head off of it so I can measure the head gasket thickness. I have to read up on the cam timing procedure first so I can take it apart properly and not cause myself undue difficulty in the re-assembly...

[geargrinder]

great stuff thaddeus as usual. love the ring-gap stuff. no time to delve into my car these days but still. always fantasizing about somebody finding a new route on these that is not crazy costy to make them really notch it up a bit. they have good enough flow and are really pretty damn solid but are fairly unappreciated, except as you say, for the whacko scandinavians but then they're always throwing them in old E30's or E34's or an antique volvo or some other whacky contraption it seems.

[RSBBlackM3]

http://bavarianmachine.com/bmw-repair-shop/

This bmw machine shop in Houston TX offers rebuilds on M6x engines. Perhaps they would be willing to shag a few questions if anyone wants to call. Im subbing, this is a good thread!

[wagons ho]

Sorry for my hiatus, but I was sick for ten days. Madly working on the S/C mounting in between work and wife's vacation so engine rebuilding has taken a bit of a break. Soon I will need a 4.4 to test all of our theory's on. I am regapping the rings on one of my cores to .022 top and bottom. A 200,000 mile engine still only had .003" piston clearance and .012 ring gap. 97 composition head gaskets are .065 thick compressed, and the 98-03 mls are .070 compressed. The special thicker gaskets are .100" uncompressed, which is not enough to really change much. Naturally I will be abusing this engine as the S/C tune progresses so if it survives we'll know if ring gap is a precursor to failure. S/C mounting parts are showing up from the various machine shop's and i should have the final fitment of everything soon.

[tptrsn]

The special thicker gaskets are .100" uncompressed, which is not enough to really change much.

Might you know what they compress to? I'll do a bit of my fancy super-approximate math and see what I come up with. Lol

Regarding your ring gaps, I like the top ring spec a LOT! But most companies suggest a slightly larger second ring gap to avoid ring flutter. Not really sure what the ring flutter stuff actually means in practice...

[philly98540]

Wow, almost no measurable ring or piston wear after 200k! That block material works well to mimimize wear.

[tptrsn]

That really is pretty insane!

[Kenny1958]

Hi Guys

Postman came today and delivered some Polish goodies.

[tptrsn]

NICE!!! How do they feel in-hand?

Any idea when you will be able to get some bolts in them and take some initial measurements?

[evomel]

I tried reading thru this thread and knowing what it entails after suffering through it - if you want a proper way to do this it would be best to just buy a NEW 4.6 block which are still available from BMW for 3-4K and build around that-- all this time spent and I know there will be suffering will just backfire on you- my end result was finding a 36K mile engine and swapping it in- if I had the funds I;'d get a 4.6 engine or block and build own that -- BUT then again thats if you want to stay BMW- cause in todays world you can build the baddest LS engine and you can BUY NEW BLOCKS!!!! new internals and cam and heads for less than the cost of a 4.6 block!!! so choose your arsenal many LS's out there LS2-3A7-X pick your monster and you can see power figures that you could only dream of your BMW ever making natural aspirated--- if you have the extra funds add a Turbo or SC on top and your a SLEEPER!!!

[Kenny1958]

I tried reading thru this thread and knowing what it entails after suffering through it - if you want a proper way to do this it would be best to just buy a NEW 4.6 block which are still available from BMW for 3-4K and build around that-- all this time spent and I know there will be suffering will just backfire on you- my end result was finding a 36K mile engine and swapping it in- if I had the funds I;'d get a 4.6 engine or block and build own that -- BUT then again thats if you want to stay BMW- cause in todays world you can build the baddest LS engine and you can BUY NEW BLOCKS!!!! new internals and cam and heads for less than the cost of a 4.6 block!!! so choose your arsenal many LS's out there LS2-3A7-X pick your monster and you can see power figures that you could only dream of your BMW ever making natural aspirated--- if you have the extra funds add a Turbo or SC on top and your a SLEEPER!!!

I appreciate your input and will keep in mind what you say, this new engine is just a stand in with lower compression for running the charger, the new one will be lined and forged to expect 500whp at most.
I`m gonna read through your threads again cheers!

[geargrinder]

Hi Guys

Postman came today and delivered some Polish goodies.

I was hoping for pierogies.

[Kenny1958]

NICE!!! How do they feel in-hand?

Any idea when you will be able to get some bolts in them and take some initial measurements?

They feel quite nice almost smooth certainly not as sharp as OE. I need to get some 3/8 x 43mm rod bolts asap
I have 4 days off work and the Engine is now on a stand being cleaned and taken apart ready to fit the new rods and gap the rings.
This engine has been apart before all the gaskets look to be silicon the the engine was very grimy hope i dont find anything bad there ??

[tptrsn]

I tried reading thru this thread and knowing what it entails after suffering through it - if you want a proper way to do this it would be best to just buy a NEW 4.6 block which are still available from BMW for 3-4K. . . in todays world you can build the baddest LS engine and you can BUY NEW BLOCKS!!!! new internals and cam and heads for less than the cost of a 4.6 block!!!. . .

You seem to have missed the point of the thread.

[JimLev]

I was hoping for pierogies.

Some kielbasa and a few beers too.

[evomel]

I appreciate your input and will keep in mind what you say, this new engine is just a stand in with lower compression for running the charger, the new one will be lined and forged to expect 500whp at most.
I`m gonna read through your threads again cheers!

I'll have to read through your threads more in depth - I'm actually getting back my old engine and I was going to just take it apart and sell the heads(which are brand new benched with super angle job) block and so on-- but maybe I should hold onto it take it apart and sleeve like you are?

[wagons ho]

Oh. Wait,I'm confused. evilmel ,sorry evomel. Now you want to join the discussion?? I thought you were selling your bmw as soon as you could and getting a mustang and/or putting a LS in something for more power? Your signature indicates you sure love your car with all the trick parts you invested in. I'm willing to spend time and money to get more power from a mere 268 ci because I feel there's a bump available. LS engines are good, but a customer of mine was towing his LS powered chevelle that had a lifter failure, when his Silverado tow rig crapped a lifter and took out the cam. A twofer!

[evomel]

Oh. Wait,I'm confused. evilmel ,sorry evomel. Now you want to join the discussion?? I thought you were selling your bmw as soon as you could and getting a mustang and/or putting a LS in something for more power? Your signature indicates you sure love your car with all the trick parts you invested in. I'm willing to spend time and money to get more power from a mere 268 ci because I feel there's a bump available. LS engines are good, but a customer of mine was towing his LS powered chevelle that had a lifter failure, when his Silverado tow rig crapped a lifter and took out the cam. A twofer!

LOL so funny!!!! why are you buying my car????????make u a sweet deal !!!!!!! I wouldn't compare some rinky dinky Silverado to a BUILT LS motor -

[Kenny1958]

I've been pulling apart the motor that is going to have the decompression rods in and i have found out it has had new chain guides but i also found out that the grub screw that holds the oil separator outlet has been omitted. I also found bits of the old chain guide in the pan and every gasket has been made with silicon over all the old gaskets.

[Kenny1958]

Here are the bores.

[philly98540]

Any wear in the bores? Hard to tell from the pics.

[geargrinder]

Oh. Wait,I'm confused. evilmel ,sorry evomel. Now you want to join the discussion?? I thought you were selling your bmw as soon as you could and getting a mustang and/or putting a LS in something for more power? Your signature indicates you sure love your car with all the trick parts you invested in. I'm willing to spend time and money to get more power from a mere 268 ci because I feel there's a bump available. LS engines are good, but a customer of mine was towing his LS powered chevelle that had a lifter failure, when his Silverado tow rig crapped a lifter and took out the cam. A twofer!

LOL that's a bummer! of course our own RVAE34 had his fresh crate LSx eat itself up super early it its life so it IS worth noting those motors are not immaculately perfect...

[Kenny1958]

Here's some close up bore shots they seem to be in good condition bar a few light marks.

[philly98540]

Cool. These specially made aluminum blocks seem to defy wear. Great stuff if well cared for and not overheated.

Also, +1 on the LS stuff. They fail too.

[evomel]

Those walls look good - my point on the LS's is that you can just buy a NEW block and customization is HUGE compared to these old m62 blocks no longer available in NEW form -- sooner or later they will need to be replaced completly --- just choose your weapon