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M20 Turbo => M50 turbo fun.


Rowleym

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Yup. Bought it. He gave me a wastegate too. It's in super good condition. Yea I have it on Craigslist and one guy is going to buy it if I still have it in 5 days. But he wants it for 300. Whatever. Hopefully someone gets it for 400. It's a damn nice turbo. Best hx40 too. Welded the wastegate shut tonight. And I learned to tig weld! Posted Image also, this dude is going to help me make a short runner intake. It's going to be super gnarly. Gonna find a huge throttle body off some gm and put it on there.

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Simple, a larger throttle body will let in more air when you push the pedal down the same distance as before. As a result, I have to use a very light foot when driving my car. I found it easier to modulate the throttle when leaving from a stop with an OEM throttle body. If you do want a monster throttle body I think I have a land rover one that you're welcome to. Just pay shipping. I may or may not still have it though... hard to remember.

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I stole this from the accufab site;

For instance, the popular 5.0 Ford Mustang typically was equipped with a 60MM throttle body from the factory. This equates to a flow rating of 495 CFM. The Accufab 5.0 Mustang replacement throttle body sizes start with 65MM. The 65MM unit flows 664 CFM. This is a CFM flow increase of 34%. The Accufab bolt on replacement throttle bodies are available with units up to 105MM for the 5.0 Mustang. The 105MM unit will flow 1550 CFM, way more than triple the stock flow rating. Of course, only a serious race engine could even come close to benefiting from that amount of airflow.

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I am not sure how this would work with a turbo setup, but on an NA engine you would want to measure the pressure difference across the throttle body. Connect a vac. gauge to a vac. port upstream of the throttle body and take readings at full throttle+high rpm, then repeat with the vac. gauge connected to the manifold (downstream of the TB). I'd imagine you would want to run the smallest throttle body that gives 0 (or virtually 0 ) pressure drop.

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Going a new direction! Swapping in an m50. Anyone wanna buy a m20 with 128k on it? Also hooked to an auto trans so it was never over revved. Getting a m50 with 135k on it. Hopefully I don't have to replace too much. Too bad I just spent a bunch on money on that damn m20..

Why the change of direction? I love me some M20 but mine is healthy at the moment. No need for another one yet, otherwise i'd be after you about it.

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Your logic is definitely sound.

It would be silly to try and say the M20 is a better engine than the M50 but I think the point at which my jimmies become rustled is when someone has an M20 in a poor state of tune (see also too cheap to hunt down vac. leaks and replace old parts) swaps in a junkyard M50 and pretends the M20 was a total un-fixable pile and the M50 is a rocketship, when in reality, a tune up would have likely yielded the same performance increase.

One thing to keep in mind about the M20, is that in NA form, it was a very highly optimized engine for its day. The LS1 is praised for being such an optimized engine with only 2 valves per cylinder, but when you do the math, the M20 has a specific output very close or equal to that of the LS1 (depending on the version of LS1) and that is with an archaic EFI system and relatively low compression ratio. Being reasonably optimized means that there is not a whole lot to gain unlike a 350 chev with 190 hp which gains 100hp with a carb, manifolds, and a cam.

So yes, the M50 is a more advanced engine, has more area under the torque curve, is more refined, and capable of making more power with less sacrifice down low, but the M20 aint a bad gig either, especially when the cost of replacement is so low, especially when your snail-obsession gets out of hand.

Edited by Snap Understeer
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