M20 B3x Naturally Aspirated Stroker build past, present and future

[Mr Mpower]

BTW in this picture, in the 2nd harmonic:

when you write to 2x2" at the first pipe, you are talking about 2 pipes of 2"OD i think

but when you write 2x2 25" in the final pipe, are you refering to 2 pipes of 2,25" OD or 2 pipes of 2" OD and 25" lenght ?? sorry for the silly question but i use metric system and sometimes is tricky to understand some things. Thanks again!

[digger]

late night rethinking about this setup, the m52 is 24v and m20 is 12v, the 2nd harmonic setup you’ve designed should work fine in the 24v config aswell ?

Yeah length is mostly an rpm thing so 2v 4v not a meaningful difference

[Mr Mpower]

Euro m3 headers would be better ;)

late night rethinking about this setup, the m52 is 24v and m20 is 12v, the 2nd harmonic setup you’ve designed should work fine in the 24v config aswell ?

[digger]

i was waiting for a really negative comments about the manifolds, but you are absolutely polite, hahah.

really than your time and effort in all this and waiting for more advances in your build.

Euro m3 headers would be better ;)

[Mr Mpower]

2200mm total from head for x-pipe location. since front 3 and rear 3 are different positions just take average. When you have 2200 mm length a difference of 200 mm is 10% which is not much. but if you had a system with 800mm then 200mm variance is 25% so you need to more accuarte when the system is short but not so much when its long.

i dont think there is a need to stagger cats you cant get the two (2) collectors the same anyway

X-pipe i think is just a better flowing H-pipe, but either will do the same job

i was waiting for a really negative comments about the manifolds, but you are absolutely polite, hahah.

really than your time and effort in all this and waiting for more advances in your build.

[digger]

Ok, i understand, your dedication is priceless period.

By now, the manifolds need to be OEM so this are my primaries and secondaries, giving that like you see in the picture left side is shorter than right side, i need to staggered the kats a bit to have the same leght from the primaries?
In this case where the primaries are so short, the 2200mm total lenght still being the best choice?
i have read you a few times talking really good about the s54 desing but it uses H pipe and you are using X pipe finally, wich is the main reason?

Thanks for all again, this topic must be consider as one of the best guides in the community.

2200mm total from head for x-pipe location. since front 3 and rear 3 are different positions just take average. When you have 2200 mm length a difference of 200 mm is 10% which is not much. but if you had a system with 800mm then 200mm variance is 25% so you need to more accuarte when the system is short but not so much when its long.

i dont think there is a need to stagger cats you cant get the two (2) collectors the same anyway

X-pipe i think is just a better flowing H-pipe, but either will do the same job

[Mr Mpower]

s54 as in configuration not sizes (diameters)

i favour around 1600 mm give or take with a street engine. This is in effect a total length of 2200 mm when primary (assume 600 mm) is accounted. If you use longer primary then retain total length 2200 and shorter the collector a bit and vice versa. E.g. with long tube headers which are like 800mm often then 1400mm will work ok to.

twin 2" is plenty unless its a crappy workmanship i.e. bad bends, misalignment, mismatch etc. A really nice twin 1.875" or 1.75" would also work but need to pay a bit more attention to the details include the muffler, cats, resonator sizes and efficiencies

Ok, i understand, your dedication is priceless period.

By now, the manifolds need to be OEM so this are my primaries and secondaries, giving that like you see in the picture left side is shorter than right side, i need to staggered the kats a bit to have the same leght from the primaries?
In this case where the primaries are so short, the 2200mm total lenght still being the best choice?
i have read you a few times talking really good about the s54 desing but it uses H pipe and you are using X pipe finally, wich is the main reason?

Thanks for all again, this topic must be consider as one of the best guides in the community.

[digger]

We don’t have enough words to thank you all your info and all the time you take to learn and to share this...is priceless

i have arrive to your post looking for a setup for my engine.
is a m52b28 2800cc 6700rpm for street use close to stock in fact, stock cams and stock intérnals.

I need to do a new exhaust for it and if i understand well, in your investigation for street use, the s54b32 exhaust offers a good base for it.


So taking in mid that from OEM m50/m52 uses twins 1,75” ID for the secondary pipes and the s50b30 use twin 2,25” I thing is not bad idea to use twin 2” ID For the new one

with that say your 2th harmonic with s54 base setup with kats sounds that best bet for me.

so for the secondary pipe 2 twins 2”(50mm) pipes with 1600-1700 leght (kats include) looks nice in my mind
giving that I don’t know if is better to use and H pipe or a X pipe because in your setup you use the X pipe but in the s54 setup that you recommend they use H pipe.

about the final pipe at first I was thinking to go twin 2” too with the muffler and twin 2,125” tail pipes, ¿is worth use 2.25” for the final pipe in place of the 2”?

I really appreciate your opinion into my setup

s54 as in configuration not sizes (diameters)

i favour around 1600 mm give or take with a street engine. This is in effect a total length of 2200 mm when primary (assume 600 mm) is accounted. If you use longer primary then retain total length 2200 and shorter the collector a bit and vice versa. E.g. with long tube headers which are like 800mm often then 1400mm will work ok to.

twin 2" is plenty unless its a crappy workmanship i.e. bad bends, misalignment, mismatch etc. A really nice twin 1.875" or 1.75" would also work but need to pay a bit more attention to the details include the muffler, cats, resonator sizes and efficiencies

[Mr Mpower]

We don’t have enough words to thank you all your info and all the time you take to learn and to share this...is priceless

i have arrive to your post looking for a setup for my engine.
is a m52b28 2800cc 6700rpm for street use close to stock in fact, stock cams and stock intérnals.

I need to do a new exhaust for it and if i understand well, in your investigation for street use, the s54b32 exhaust offers a good base for it.


So taking in mid that from OEM m50/m52 uses twins 1,75” ID for the secondary pipes and the s50b30 use twin 2,25” I thing is not bad idea to use twin 2” ID For the new one

with that say your 2th harmonic with s54 base setup with kats sounds that best bet for me.

so for the secondary pipe 2 twins 2”(50mm) pipes with 1600-1700 leght (kats include) looks nice in my mind
giving that I don’t know if is better to use and H pipe or a X pipe because in your setup you use the X pipe but in the s54 setup that you recommend they use H pipe.

about the final pipe at first I was thinking to go twin 2” too with the muffler and twin 2,125” tail pipes, ¿is worth use 2.25” for the final pipe in place of the 2”?

I really appreciate your opinion into my setup

[digger]

I'm still waiting to hear back from ATI, they have been very slack in responding. i have a new OE one on the shelf and a low mileage one but its not going to be particularly well suited to mine. i'm sure it would work well in normal driving and occasional short bursts to 7500 but id like to buzz mine to 8000rpm if the power curve is sufficient to warrant

that dyno above is a flywheel number, its not whp as how most in US or Oz would expect. he hasnt build that other engine with those specs yet it was a basic 2.7. it should easily exceed 230whp with the new spec provided it is executed properly of course

[ForcedFirebird]

Hey Digger, crank hubs have been NLA fore a while. The client with the 12:1 m20b25 that exploded his damper two yr ago ('19) went with a modified ATI unit that was drilled for the m20 crank snout, then modified a v-belt pulley to suit. He is still banging 8500rpm and it's held together for the 2020 season. Pretty sure we will see some more power this 2021 season, he peaked at 208whp/198wtq last year, but when he sent his head in for a refresh in Jan, I was able to get another ~12-14cfm on the intake side from ~.200-.350" valve lift. Will post results in the dyno thread once it's together.

Hi, they use a SuperFlow AutoDyn 30 AWD dyno if that clarifies things for you!?

Short vid of the car on the track:

https://youtu.be/YFAlrWJ0lEk

I'm looking to get a new head, 44-45mm intake valves, cam 292 or up, 12.4 or higher CR pistons and ITB's (tapered 45>42mm) for this year and maybe get another 20-30HP out of it... but posting my wants here is off-topic I guess :D

Yes, it does. At first, I thought your HP number was a little high (hence the comment about W vs B HP). But, then realized today reading back that your numbers are metric. That brings us closer to the SAE 215lbft I have seen many times. After conversions you are making 234whp/215wtq SAE, which is right on par for your upgrades. It seems like getting over the 230whp mark is a bottleneck for these single cams without diving deep into the valve train (oversized seats, custom/roller rockers/cam etc).

No one said the stock manifold "can't", it's just not as easy as using ITB. Just putting RHD ITB's on a bone stock m20 picks up almost 20whp.

[digger]

I'm looking to get a new head, 44-45mm intake valves, cam 292 or up, 12.4 or higher CR pistons and ITB's (tapered 45>42mm) for this year and maybe get another 20-30HP out of it... but posting my wants here is off-topic I guess :D

that should make a big difference to power but it is hard to find good head porters though. if you only gain 30hp with those modifications then there is seriously something wrong

[beemaestro]

stock manifold is good for around 220-230 whp +/- which is around 250-260 bhp+/- so yeah 235 SAE hp at flywheel is achievable.

years ago a guy build a 2.7 whith good CR stock manifold and huge dbilas cam 312 degrees or something crazy and it still fell with this ball park.

It does come down to your definition of proper power

It think with fairly basic components like 81mm crank, 272> cam, headers, anything over 210-215hp is bonus

[beemaestro]

You have to compare apples to apples. Is that a real wheel power number, or that weird calculation of brake power calculated from wheel power?

Hi, they use a SuperFlow AutoDyn 30 AWD dyno if that clarifies things for you!?

Short vid of the car on the track:

https://youtu.be/YFAlrWJ0lEk

I'm looking to get a new head, 44-45mm intake valves, cam 292 or up, 12.4 or higher CR pistons and ITB's (tapered 45>42mm) for this year and maybe get another 20-30HP out of it... but posting my wants here is off-topic I guess :D

[digger]

I've been hearing of more of the stock units exploding with age and they have gone NLA as far as I'm aware, nice to see we have some options in the works.

yeah but it might be spendy enough to keep people away though, like other ATI vibration dampers for BMW's....though when i bought a new OE one it was still a few hundred