944 2.5 with little Eaton??
09-02-2013, 07:57 AM
#121
A lot of the Eatons have a built in bypass valve that cycles air from the output of the S/C back to the input of the S/C. Mine shown above does. The bypass is vacuum operated, so it is only open and causes the air to be recirculated when the vacuum is above a certain level. This feature means that the rotors of the s/c rotate in a partial vacuum much of the time. If you remember your physics, this means that it takes almost no energy to rotate the s/c under these conditions. I think the M90 was spec'd to only take 1/2 hp at cruise speeds.
So, it really isn't a surge valve per se. And, the throttle body is placed before the s/c.
So, it really isn't a surge valve per se. And, the throttle body is placed before the s/c.
Thanks for that explanation, that is a very neat feature. I am really looking forward to picking up the M90 this morning. The guy I am buying it from parts out Supercoupes and XR7's, so he has ALL the parts for the OEM S/C setup.
it almost seems too easy. The fabrication part seems to be the biggest part of the equation, and I don't see that as being too difficult due to the fact I am a TIG welder by trade. Having a Rogue MAF should really simplify the fuel delivery part of it. I'll also need a HOT coil, which Josh at Rogue can also help with and I've got all the right stuff.
What am I missing?
09-02-2013, 12:37 PM
#122
Rennlist Member
Not sure if I've posted this photo here in this ancient thread or not. But here is my 86 NA motor with Eaton M90 poopercharger.
It was slow and I blew the motor up after a couple weeks of driving, and it has been sitting now for 3 years while I put together a new engine so don't ask me how much I like it.
It was slow and I blew the motor up after a couple weeks of driving, and it has been sitting now for 3 years while I put together a new engine so don't ask me how much I like it.
09-02-2013, 01:05 PM
#123
Not sure if I've posted this photo here in this ancient thread or not. But here is my 86 NA motor with Eaton M90 poopercharger.
It was slow and I blew the motor up after a couple weeks of driving, and it has been sitting now for 3 years while I put together a new engine so don't ask me how much I like it.
It was slow and I blew the motor up after a couple weeks of driving, and it has been sitting now for 3 years while I put together a new engine so don't ask me how much I like it.
09-02-2013, 05:45 PM
#124
Rennlist Member
The old tune was very unprecise and barbaric and inevitably was the demise of my engine I'm pretty sure. The new tune will be a full Megasquirt system and done right, and on a big bad motor.
09-02-2013, 09:19 PM
#125
I'm kind of thinking that fuel delivery was the big hurdle in the past. Josh at Rogue seems to have that part of it sorted.
I am still trying to figure out if I am pulling through the MAF into the S/C or blowing through. I'm thinking it's blow through, but not sure. I see on your setup Elliot that you were pulling through the AFM.
I am still trying to figure out if I am pulling through the MAF into the S/C or blowing through. I'm thinking it's blow through, but not sure. I see on your setup Elliot that you were pulling through the AFM.
09-02-2013, 10:34 PM
#126
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I was running "speed density" to run my Mazda/Probe KL engine. Spd. density only uses rpm for the engine speed, and inlet air temp and manifold pressure for density and the volumetric efficiency table to calculate the air intake so it can add the right amount of fuel. It is a very simple system, and I believe MegaSquirt allows this option for engine control. There is only one downside. If you make changes to your setup which might impact the Vol. Eff. of the engine, you have to adjust that table. But with wide band O2s that shouldn't be an issue. But if your build (in terms of the engine intake/internals/exhaust don't change, it is an easy way to go.
