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Discussion Starter #1
I'm sure many of you who have scoured Youtube for GTV6 videos has found this nice piece of work:


Man, this guy can lay carbon. I don't know if I would have that much exposed weave but irregardless those are some very nice pieces. Anyway, his Eaton setup looks great. Seems like he's achieved a great balance of economy and performance. But I always assumed that when something's too good to be true it probably is...

Does anyone run a setup like this? Thoughts?

Let's set aside the feasibility of engine management for a moment and assume that component of the project is doable (I believe it is), what are some other snags and downsides that might crop up? I think the other big hurdle would be totally isolating the S/C and NA systems so when you switch you don't loose pressure out of the NA air filter and when you're on NA your MAP/MAF readings aren't totally thrown off by having the S/C plumbing.
 

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The Eaton M62 that he used for the project comes with a clutch drive in it's normal Mercedes home. Works and looks like an AC clutch. Part throttle and the blower vanes are spinning freely, mash the gas and the clutch engages = boost.

Not sure why he went with a completely separate NA intake as drawing through the blower doesn't hurt you much - most GM M62 setups do this with the air bypass valve open. The Merecedes works this way too.

Throttle linkage must be complicated to keep from losing boost, and then provide NA drivability. That's probably the only down side.

Really nice work on all the components and it looks like the system works - so Kudos there.

Engine management is no big deal - Air/fuel ratio, spark timing all the same ruels apply for NA or boosted, boosted engines just run at a different manifold pressure. It's not like you need to switch maps, you are just running in a different area of the map when NA.
 

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Discussion Starter #3
Mark, I was hoping you'd chime in. Seems like this setup basically has an air bypass valve that pulls from an entirely different filter.

I probably won't go with the Mercedes style setup. I'm forgoing a turbo setup to maintain as linear a driving experience as I can have and that setup allows for more lag than I'd like. I'd rather have it switchable like the car in the video. I'm either cruising, thinking about efficiency, or I want all the performance all the time.

There's a very good chance I would go with an electronic throttle. Most ECUs I would run in this setup have support for it. It would allow me to tune in a lot of control for drivability. On that note, yeah I'm not worried about the ECU at all. But I know there are some on this forum who aren't comfortable with that tech and Zep's turbo thread got sidelined with that discussion for a bit.

Running everything in one map will hurt resolution. The ECU I have my eye on has a 26x26 map, which should be plenty large enough, but some are only 13x13 or so and that's probably too small to run two entirely different maps in. The advantage of running one map is easy and quick switching between boost and NA. Flipping a dashboard switch to get to the other map could have lag in the ECU, in my experience changing the entire table kills the outputs for just long enough that the engine often stalls. That can all be experimented with later.
 

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"Seems like this setup basically has an air bypass valve that pulls from an entirely different filter." Yes, looks like that.

Your plans for a clutched system should work fine. Some are nervous about clutching, but it's just a matter of patience with tuning. The Mercedes system can work like that - It just depends what you hook the switch to; the throttle or a dash switch :)

You can draw through the blower when it is "de-clutched" so an air bypass system like the one in the video isn't necessary. Though the thought is probably to reduce the vacuum in the manifold off-boost - i.e. "flows better".

The map resolution issue makes sense for any boosted application - bigger range from -14.7 to max boost than NA, but spread over the same number of bins = less resolution.

E-throttle is an interresting path. I'm not sure I'm ready to take that plunge. It would eliminate the need for a throttle damper, but I'd want to know that the system is fail safe. Double springs on my mechanical throttle (an always rule) give me enough confidence to experiment. The OEM E-throttles I have seen are stepper dirve and have no return springs. You really have to trust the software and know that there will be no EMI issues to confuse the controller.

It's a fun project - lots of learning. God I hope I get mine running soon.
 

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Discussion Starter #5
Luckily I have access to a flowbench so I could flow the blower and see what kind of losses and vacuum you get from pulling through it. If I get my hands on an M62 this summer I'll give that a try. By the way, what's a good price for an M62? Are they all created essentially equal or should I look for one off of the Mercedes?

I've had some thoughts with the electronic throttle. Right now my favorite option is a cable operated stepper motor disengage. Just a pull cable somewhere on the dash that will let the throttle plate close on the return springs. I'm feeling pretty trusting in an E throttle, it just opens up a LOT of possibilities.
 

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I like the Mercedes unit because the input snout is so short and the ports are "easy" to mate up to. I eliminated the clutch on mine so it is a direct drive.

The GM units are readily available and they include the bypass valve, which is nice. But they are long. I think this is what Greg Gordon uses for his kit, so you can make them fit.

There are several generations of the M62, with the gen IV being more efficient than the Gen III, etc. However, the working guts of the blower are the same within each generation, only the cases are different. Magnuson are supposed to be the same as the Eatons.

I got mine for $300 a few years ago. I thought I did well, since the blower was essentially new and the electric clutch was burnt out. I didn't want the clutch anyway. You can get the GM ones of E-bay for $150, but they are likely good for mockups. They can be rebuilt. Good hunting.
 

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Toyota also ran clutched superchargers and bypass valves on their old 4AGZE and 1GGZE engines from the mid 80s (these were 'ye olde' straight, 2 lobe per rotor, superchargers and have nothing on the much more modern Eaton SCs). I think its partly to do with fuel economy and partly to give better service life from the 'charger as even though the engine will pull enough air through the SC to cause the rotors to turn when the car is just cruising down the road, they obviously aren't turning at their normal drive ratio speed.

The GTV6 is definitely interesting with some impressive quality of work, but it seems more involved than it really needs to be and I would be curious about its transition from SC off to SC on.
The Toyota's switched the clutch on before the bypass valve has closed, so the transition is basically unnoticeable.

For pure fuel economy, rather than developing a rather elaborate and ultimately cost adding system like the GTV6 has, just tune your part throttle area's of the fuel map to run leaner than stoichiometric. Cruise with a 16+:1 AFR will give a decent reduction in fuel consumption.
If you did use a clutched Merc SC M62, rather than using some huge throttle body as a bypass valve, use either a tiny TB (40mm would be plenty) or an external Eaton bypass (butterfly) valve. That will keep the installation compact and be more inline with how car manufacturers do it.

At the end of the day, if you want to be fast, the SC will be in play.
When cruising, the engine uses such little air that there is no need for another 75mm TB that completely bypasses the SC.
When I set up my Adaptronic to run my supercharged MR2, I used a combination on inputs to get the computer to switch on the SC clutch (bypass valve is purely pneumatic based on vacuum in the pipe between the TB and the SC). I used a set TPS percentage AND a set MAP sensor (vacuum) setting to be required for the computer to switch on the SC. Switch on is **** near seamless and the car will cruise down the highway without the SC on with enough leeway so it's not 'just' about to switch on with slight ankle flexes for minor hills or head winds.
Obviously if I need/want to use the added go, flex the ankle some more and on comes the SC, but always before the bypass valve had closed.
 
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