I'm not sure if it's covered anywhere in this forum, but there are some differences between the intake manifolds and throttle bodies throughout the years of the m6x engines. I thought it was as simple as the m60 vs m62 manifold, but apparently there is more to it. I found some info on bf.c and then looked at my own manifolds and throttle bodies that I have sitting around to confirm it.
Turns out, the early m60b40 had an intake manifold with velocity stacks attached to the runner ports internally. This was done away with at some point, as the late m60b40's had no velocity stacks, and squared-off intake runner ports. Then, When the m62b44 (non-vanos) came out, they rounded out those ports on the runners. When the m62b44tu came out, they did away with that intake manifold entirely and switched to one with much smaller ports, which belongs in the trash can.
There seems to be one common way to differentiate between the two m60b40 manifolds. The early have 4 fuel rail bolt holes, the late model has 5. It would still be better to look inside to double check, though.
I think it's safe to say that the early m60b40 manifold with the velocity stacks would be the best option, followed by the m62b44 with the rounded ports, followed by the late m60b40 with the squared ports.
This is the early m60b40 manifold, with velocity stacks
This is the late m60b40 manifold. Square runners, no velocity stacks
This is the m62b44 (non-vanos) manifold. Rounded off ports, no velocity stacks
Then, there are some throttle body differences. I *think* all m60b40 throttle bodies have a wedge installed, with the purpose of limiting airflow when first cracking open the throttle, to sort of tame the engine from it's throttle response, to prevent lurching off idle. This is fine, but it adds about 3x the thickness to the throttle plate, which would create some turbulence and limit flow a bit.
I think all m62b44 (non vanos) engines come with a normal flat plate throttle body, of the same size, that bolts right on (since it's the same intake manifold. I'm still working on verifying this.
I tried to pull the ACS throttle plate off and swap it with the actual throttle body plate, but the 2 mounting holes don't line up.
Turns out, the early m60b40 had an intake manifold with velocity stacks attached to the runner ports internally. This was done away with at some point, as the late m60b40's had no velocity stacks, and squared-off intake runner ports. Then, When the m62b44 (non-vanos) came out, they rounded out those ports on the runners. When the m62b44tu came out, they did away with that intake manifold entirely and switched to one with much smaller ports, which belongs in the trash can.
There seems to be one common way to differentiate between the two m60b40 manifolds. The early have 4 fuel rail bolt holes, the late model has 5. It would still be better to look inside to double check, though.
I think it's safe to say that the early m60b40 manifold with the velocity stacks would be the best option, followed by the m62b44 with the rounded ports, followed by the late m60b40 with the squared ports.
This is the early m60b40 manifold, with velocity stacks
This is the late m60b40 manifold. Square runners, no velocity stacks
This is the m62b44 (non-vanos) manifold. Rounded off ports, no velocity stacks
Then, there are some throttle body differences. I *think* all m60b40 throttle bodies have a wedge installed, with the purpose of limiting airflow when first cracking open the throttle, to sort of tame the engine from it's throttle response, to prevent lurching off idle. This is fine, but it adds about 3x the thickness to the throttle plate, which would create some turbulence and limit flow a bit.
I think all m62b44 (non vanos) engines come with a normal flat plate throttle body, of the same size, that bolts right on (since it's the same intake manifold. I'm still working on verifying this.
I tried to pull the ACS throttle plate off and swap it with the actual throttle body plate, but the 2 mounting holes don't line up.
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