I read sooo many posts.... but what’s the real deal?

[nah2323]

It’s at the shop now, getting some all around love, but I’m going to do the exhaust in little bits and pieces. I want to try a little of this and a little of that without going all in on stuff and not liking it.

As far as the tips are concerned, I think the placement of them is key, and nothing drives me crazier than having tips hanging out the back like a diving board. I’m not into them for a huge amount, and if I don’t like them I can easily swap them.


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[adamnur]

So Adam, you left everything including the resonator stock, and just straight piped after that?


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Yes, just the mufflers were replaced with straight pipes to dual exit tips on each side.

The best I found so far is this: Eliminate center resonator with X pipe, sizable improvement in sound. If that is not enough eliminate both mufflers with Y pipes and tips.

I still need to hear this resonator/straight pipe combo sound...any sound clips available?

[dragon850]

Yes, just the mufflers were replaced with straight pipes to dual exit tips on each side.




I still need to hear this resonator/straight pipe combo sound...any sound clips available?

I decided to leave the remus mufflers on my car with an x pipe. The x pipe and muffler delete cars are all late Jons cars, when I get up to the ranch next time I will take a video.

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[XAlt]

Will that 2x m20’s tied together myth ever die?
If you’ve ever worked on an m20 & an m70 you’ll know that they have absolutely nothing in common except a few generic parts.
People still haven’t figured it out....

The M70 was the very distant evolution of the "hackjob" V12 intended for the E23, but that's about it.

[killian665]

It’s not a myth lol. They have the exact same stroke, compression ratio, bore, they’re both SOHC. The only real difference is it’s an aluminum block. It’s two 2.5L M20s joined at the hip with some updates and a timing chain instead of a belt.

[whiteghost1]

I apologize to the OP in advance to pollute your thread, I just have to state the facts as I know them to quell this perpetual 2x M20's joined together statement once and for all.

It’s not a myth lol. They have the exact same stroke, compression ratio, bore

Wrong.

The only real difference is it’s an aluminum block

There's quite a bit more to it than that. I guess a lot of engines must be the same with such arbitrary guidelines. Might as well call an M62 two M42's joined at the hip together according to your intellegent logic.

It’s two 2.5L M20s joined at the hip with some updates and a timing chain instead of a belt.

Is it now......keep reading.

Lets look at the differences that really matter and see if what you are saying holds water. Those that ACTUALLY KNOW these engines and don't regurgitate info off of the interwebz + research the facts, can conclude if they are the same or different:

M20 vs M70

M20 bore (mm) = 80 or 84
M70 bore (mm) = 84

M20 block = cast iron
M70 block = alusil

M20 exh port = nicely radiused w/ceiling
M70 exh port = flat floor

M20 exh port profile = round
M70 exh port profile = square

M20 intake port profile = rectangular
M70 intake port profile = round

M20 stroke (mm) = 71 or 75 or 76 or 81
M70 stroke (mm) = 75

M20 compression = 8.8:1 or 9.7:1 or 8.5:1 or 9.0:1 or 10.2:1 or 11.0:1
M70 compression = 8.8:1

M20 pistons = flat top or profiled
M70 pistons = flat top

M20 rods (mm) = 130 or 135
M70 rods (mm) = 135

M20 cam drive = belt - manually tensioned w/pulley
M70 cam drive = chain - hydraulically tensioned w/guides

M20 cam clearance = manually adjusted
M70 cam clearance = hydraulic lifters

M20 cam gear drive = fixed timing
M70 cam gear drive = manually adjustable timing

M20 cam duration = 250 or 256/258 - depending who you ask for the latter
M70 cam duration = 248

M20 intake (mm) = 40 or 42
M70 intake (mm) = 40

M20 intake (mm) = 34 or 36
M70 intake (mm) = 36

M20 intake metering = air flow meter
M70 intake metering = mass air flow

M20 PCV system = fixed tube w/orfice
M70 PCV system = volume control valves

M20 engine mounts = solid rubber
M70 engine mounts = hydraulic

M20 throttle body = cable actuated
M70 throttle body = drive by wire


Well the M20 & M70 does share the same fuel injectors, distributor cap/rotor, coolant sensor, and air filter.......you know, the parts that are crucial to the engineered design, and define an engine (you forgot those ones BTW). Let's not forget that they both safely run on 87 octane. Wow, look at all of the similarities!

[jeffbebe]

Very interesting info, Whiteghost. Pity Killian’s just a troll so your facts won’t matter.

Back to the OP, I removed the cats and fitted a X pipe just before the stock resonator with some fairly cheap magnaflow back boxes and it looks and sounds fantastic. Will record a video.

In my experience, removing the stock resonator just creates volume and drone.

[killian665]

You posted specifications from both the “i” and eta M20s to make the M70 seem less similar. Don’t worry I’d be mad too if I had to play games with my google search to convince someone my V12 wasn’t a turd lol.

All the “differences” you listed are negligible. The motor mounts are different, really lol. The internal dimensions and overall design of the engine are the same as the 2.5 liter engine. Nobody means it’s quite literally 2 M20s welded together, yes there are minor differences. But the architecture is an M20. I don’t see how anyone could argue that unless they’re like you and want to quote how the throttle opens as an architectural difference.

By that logic M6x engines aren’t related because ones got vanos and different cams. Motor mounts are different in the X5s than they are in an E39. Must mean it’s a totally different engine I guess.

[XAlt]

You posted specifications from both the “i” and eta M20s to make the M70 seem less similar. Don’t worry I’d be mad too if I had to play games with my google search to convince someone my V12 wasn’t a turd lol.

All the “differences” you listed are negligible. The motor mounts are different, really lol. The internal dimensions and overall design of the engine are the same as the 2.5 liter engine. Nobody means it’s quite literally 2 M20s welded together, yes there are minor differences. But the architecture is an M20. I don’t see how anyone could argue that unless they’re like you and want to quote how the throttle opens as an architectural difference.

By that logic M6x engines aren’t related because ones got vanos and different cams. Motor mounts are different in the X5s than they are in an E39. Must mean it’s a totally different engine I guess.

All M6x heads and blocks bolt onto one another, don't even try with that.

[dragon850]

Very interesting info, Whiteghost. Pity Killian’s just a troll so your facts won’t matter.

Back to the OP, I removed the cats and fitted a X pipe just before the stock resonator with some fairly cheap magnaflow back boxes and it looks and sounds fantastic. Will record a video.

In my experience, removing the stock resonator just creates volume and drone.

Trust me there is 0 drone if you replace stock resonator with an x pipe.

- - - Updated - - -

I apologize to the OP in advance to pollute your thread, I just have to state the facts as I know them to quell this perpetual 2x M20's joined together statement once and for all.


Wrong.


There's quite a bit more to it than that. I guess a lot of engines must be the same with such arbitrary guidelines. Might as well call an M62 two M42's joined at the hip together according to your intellegent logic.


Is it now......keep reading.

Lets look at the differences that really matter and see if what you are saying holds water. Those that ACTUALLY KNOW these engines and don't regurgitate info off of the interwebz + research the facts, can conclude if they are the same or different:

M20 vs M70

M20 bore (mm) = 80 or 84
M70 bore (mm) = 84

M20 block = cast iron
M70 block = alusil

M20 exh port = nicely radiused w/ceiling
M70 exh port = flat floor

M20 exh port profile = round
M70 exh port profile = square

M20 intake port profile = rectangular
M70 intake port profile = round

M20 stroke (mm) = 71 or 75 or 76 or 81
M70 stroke (mm) = 75

M20 compression = 8.8:1 or 9.7:1 or 8.5:1 or 9.0:1 or 10.2:1 or 11.0:1
M70 compression = 8.8:1

M20 pistons = flat top or profiled
M70 pistons = flat top

M20 rods (mm) = 130 or 135
M70 rods (mm) = 135

M20 cam drive = belt - manually tensioned w/pulley
M70 cam drive = chain - hydraulically tensioned w/guides

M20 cam clearance = manually adjusted
M70 cam clearance = hydraulic lifters

M20 cam gear drive = fixed timing
M70 cam gear drive = manually adjustable timing

M20 cam duration = 250 or 256/258 - depending who you ask for the latter
M70 cam duration = 248

M20 intake (mm) = 40 or 42
M70 intake (mm) = 40

M20 intake (mm) = 34 or 36
M70 intake (mm) = 36

M20 intake metering = air flow meter
M70 intake metering = mass air flow

M20 PCV system = fixed tube w/orfice
M70 PCV system = volume control valves

M20 engine mounts = solid rubber
M70 engine mounts = hydraulic

M20 throttle body = cable actuated
M70 throttle body = drive by wire


Well the M20 & M70 does share the same fuel injectors, distributor cap/rotor, coolant sensor, and air filter.......you know, the parts that are crucial to the engineered design, and define an engine (you forgot those ones BTW). Let's not forget that they both safely run on 87 octane. Wow, look at all of the similarities!

I think this settles it once and for all.
I love M70 for it's durability and ability to withstand quite a bit of boost on stock internals.

- - - Updated - - -

You posted specifications from both the “i” and eta M20s to make the M70 seem less similar. Don’t worry I’d be mad too if I had to play games with my google search to convince someone my V12 wasn’t a turd lol.

All the “differences” you listed are negligible. The motor mounts are different, really lol. The internal dimensions and overall design of the engine are the same as the 2.5 liter engine. Nobody means it’s quite literally 2 M20s welded together, yes there are minor differences. But the architecture is an M20. I don’t see how anyone could argue that unless they’re like you and want to quote how the throttle opens as an architectural difference.

By that logic M6x engines aren’t related because ones got vanos and different cams. Motor mounts are different in the X5s than they are in an E39. Must mean it’s a totally different engine I guess.

Yeah it's sluggish in stock form, I often joke that original engineers built the M70 with a thought of boosting it down the line lol
You breathe on M70 a little bit like 10 11psi and modified corvettes get left in the dust with drivers mouth wide open in shock...

[dukegrad98]

I love M70 for it's durability and ability to withstand quite a bit of boost on stock internals.
...
You breathe on M70 a little bit like 10 11psi and modified corvettes get left in the dust with drivers mouth wide open in shock...

Indeed. My M70 "turd" is at 10.5psi and produces 500hp as dyno verified at the wheels -- so call it just a bit shy of 600hp at the crank. Torque numbers are even higher. I could go well beyond that with minor work, like head studs, but that particular build has already well surpassed the "fun enough, what's the point" zone.

Cheers, John

[alex840]

Killian no no no my friend. Go on MWrench whitepages and read ... read a lot

[nah2323]

Yes, just the mufflers were replaced with straight pipes to dual exit tips on each side.




I still need to hear this resonator/straight pipe combo sound...any sound clips available?

That’s just plain nuts! I can’t believe how raw nasty that sounds..


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[whiteghost1]

OK, this is the last response OP I promise. Anything more after this will loose it's (factual & entertainment) value and is a waste of my time.
Some people's children.....

You posted specifications from both the “i” and eta M20s to make the M70 seem less similar. Don’t worry I’d be mad too if I had to play games with my google search to convince someone my V12 wasn’t a turd lol.

Yes I did post the specs of the “e” and “I” variants because an m20 is an m20, remember an m70 is 2x m20’s joined together, right? We all appreciate that you confirmed that they are not similar. We really do. Unlike you I've actually worked on and know both engines intricatly, and can back up my statements with data.

All the “differences” you listed are negligible.

So a cylinder head design that is COMPLETELY DIFFERENT from top to bottom is neglegible.
As is the entire cam drive system that is COMPLETELY DIFFERENT is neglegible.
As is the intake tract that is COMPLETELY DIFFERENT is neglegible.
All the other (relevant) specs I posted presumably are neglegible.
The only info I was hesitant to include was the comparison of the base metals of the primary components, which I'm not going to bother with as I don't think many would care TBH. Unlike you, I actually want to disseminate information which hopefully someone can appreciate, as I would in return. My only repsonse is - please tell us that you're only a hack mechanic who spreads fallicies and aggravation, and are not influential in the automotive industry.

The motor mounts are different, really lol. The internal dimensions and overall design of the engine are the same as the 2.5 liter engine. Nobody means it’s quite literally 2 M20s welded together, yes there are minor differences. But the architecture is an M20. I don’t see how anyone could argue that unless they’re like you and want to quote how the throttle opens as an architectural difference.

I’m glad you made a point (or two later on) about the motor mounts, I threw that one in there with a laugh whilst, because I suspected there'd be a chance you’d pick up on it.

Brilliant.

You know, I know, and everyone reading knows that you don’t have a leg to stand on so you're setting the bar, gutter low, on that one. However in case you didn't realize I also threw in other minutiae such as the cap/rotor and air filter which you forgot to focus our attention on. Oh well, can’t say I didn’t try. Perhaps you can provide actual details rather than the irrelevent/incorrect same bore, stroke, compression, or motor mounts argument.

By that logic M6x engines aren’t related because ones got vanos and different cams. Motor mounts are different in the X5s than they are in an E39. Must mean it’s a totally different engine I guess.

Well duh, the M6x are from the same engine family so of course they are the same. And to put it in your intellectual language, they have the same "architecture" and is an evolution from M60 to M62 to M62tu. Since you insist on being educated publicy, the tu (AKA vanos) in M62tu stands for technical update from BMW. And as XAlt so kindly pointed out the parts ARE interchangeable between all M6x (may run into valve->piston clearance issues with certain combos though) - unlike the M20/M70. And no he didn't get that from playing games with his google search, he actually knows what he's talking about.