1G-GTE+Eaton M90 (or similar...)

[mullett]

Just an exercise at the moment, but I'm really considering a supercharged 1G for decade to replace the existing turbo setup...after the MR2, nothing turbo feels sharp enough anymore

I've picked on the M90 because they're relatively cheap and available, can be mounted in any orientation, and *should* be capable of producing my target power figure (170RWKW). I'll probably use an ex-commodore one, they seem to go for 400-800, and usually come with bypass valves and bits that would be handy.

The engine will be a reconned gen2 block with gen3 head (just because that's what I have).

Is this power figure attainable, and does anyone have a handy blower speed/pressure calc to work out roughly how fast I'll need to spin it and the pressure required?

Practical considerations: should I make a new inlet manifold and mount the SC directly to it, which wouldn't be intercooled, or mount it ala toyota factory, lower on the block with outlet piping and an intercooler (FMIC or WTA)

Will 1G-GZE brackets allow me to mount the alternator/AC on the exhaust side of the block?

and...am I being entirely unrealistic

-RM

[Duk]

Really speaking, an Eaton M90 is to big for a 2 litre engine.
They can't operate efficiently at a particularly high pressure ratio and turning 1 slow enough to keep it within it's usable pressure ratio on a 2 litre will result in slower than ideal boost curve.
"Better to spin a smaller (positive displacement) supercharger faster than spin a larger supercharger slower." This will give you your desired peek boost pressure lower in the rev range, giving a broader torque curve.
The above quote came from a guy who builds supercharger kits (and wrote a book about superchargers, mainly for Alfa's) for Alfa Romeo's and he uses an Eaton/Magnuson MP62 on standard 2.5 and 3 litre V6 Alfa engines and managed to get (an American) 200RWKW from an internally standard (9.5:1 CR) Alfa 3 litre V6.

[mullett]

Interesting info! And that's a very impressive power figure. Is there a way to calculate the speed/pressure ratio for the M90 vs the MP62 and the real-world difference it will make? The M90 is certainly a lot more available...

-RM

[big_zop]

Definitely sounds interesting, will be keen to compare the results if you decide to do it.

Firstly, the stock 1G-GZE is set up to be TB > SC > Inlet with no intercooler. The SC sits in the same position as the AC on your 1G-GTE and the Alt is pretty much in the same spot. Then the AC is relocated to the other side on the bottom and the PS pump is above it.

A few ideas/questions to ask yoruself on the installation:
- will you run a clutched pulley setup
- will you have the TB before or after the SC
- how much of your original setup do you want to keep or would you want to keep that completely separate so you could either refit it or sell it
- the stock 1G-GZE setup is not very friendly for intercooling so it would pay to include this in the design of the install from the start
- chassis design as my GX81 has a pretty decent engine bay and its still quite cramped

[mullett]

Is that to say that you've swapped out your SC?

I haven't actually studied a 1G SC setup, most of what I've used as background was from my 4A-GZE...which was intercooled

Answers:

-Probably no clutch, the commo setup doesn't use one, and seems to return good economy
-not decided on TB, post SC was what I had in mind, with a bypass valve around the SC
-I'd remove the entire turbo setup and start again, I'd build the SC/1G on a stand and install it as one peice, then rig the piping etc with it in the bay.

As far as the design goes it's still in the 'rough idea' range at the moment, I need to get the engine on the stand and do some engine-bay measurements.

-RM

[oldcorollas]

Interesting info! And that's a very impressive power figure. Is there a way to calculate the speed/pressure ratio for the M90 vs the MP62 and the real-world difference it will make? The M90 is certainly a lot more available...

-RM

there are some data sheets on the CAPA site, as well as eaton itself

[mullett]

I've come across them, but I'm after a way to translate those figures to power/torque curves based on (I guess) the VE and size of the engine...

-RM

[mullett]

Well, looks like this might go ahead...might have sourced a rebuilt M90 out of the states for a pretty reasonable price. Going to require a few things (like relocating the oil filter), and relocating the accesories to the opposite side. Also pondering either keeping the turbo attached, or sellign the turbo install and just running headers...

-RM

[RA35GT]

I LIKEY ALOT!

piss off the turbo, or get a bigger one

[mullett]

Haha, and put a PROPER hole in the piston

Still can't shake the feeling that M90 is too big, but I guess the only difference is the parasitic loss. Also pondering using the scooby WTA cooler I've got, or sticking with a front mount...

-RM

[Pimpin_1JZ]

Well, put it this way, the M90 powers the TRD Aurions which are a 3.5 V6....

[mullett]

Also the commodores, which is a 3.8 Also plenty of yank stuff up to 5L...

That said, an RB25 turbo can happily be used on a CA18...

What I'm getting at is that I'm not sure exactly what the losses and benifits are of running too-large a supercharger (in real-world applications). It's going to be slightly less efficient coming on boost, but compared to a turbo (or SC14) this is probably irrelevant...

-RM

[mullett]

Just did some rough calculations, to get 14psi of boost I'd need to spin an M90 to about 10,000rpm (in a perfect world)

Engine air usage (at 1ATM)= 2L*7500rpm/2=7500L
Pressure ratio 2:1= 15000L/min airflow
M90=1470cc/rev= roughly 10,000rpm
M62=1000cc/rev= 15000rpm

So an M90 would seem to be the more logical choice, obviously it becomes less efficient at this high of a boost level, so my 'ideal' calculation isn't perfect, but the engine would also use less than 7500L of air, as it wouldn't have perfect pumping efficiency.

The side note of that is that an SC14 running at 10,000rpm would move the same amount of air...but certainly wouldn't make the power. Pumping losses? Heat loss? How much more efficient IS an M90?

-RM

[amichie]

Isn't the m90 only marginally bigger than an sc14? Maybe just use an 1g-gze setup and add an intercooler and special pulley to get the boost you want.

Bigzop. This is your domain. Any comments.

[mullett]

Having already found the limitations of an SC14 (and it's nowhere near the power I'm after) I wouldn't use one, especially when they're about the same price as an M90...

-RM