So my Jaguar has an Eaton M90. It is a traditional roots type with a displacement of 90ci/rev (1.5L). I think it is already pretty well maxed out due to heat. The stock power was 315 hp from a 4.0L straight 6 which seems about right for an M90.
I was looking for options to get the power up. Junkyard supercharger swap seemed like a possibility. It only displaces 1.2L BUT it is a twin screw design that runs much cooler and lower mass on the rotors. I am not sure that it would be worth the effort in this application but it got me thinking about potential future swaps as they seem to have similar value on the used market.
What says the Hive?
Any reason not to just swap up a size and run an Eaton M112? That's what Jaguar used on the supercharged V8 cars that came after yours.
That is likely what I will go with if I upgrade. I might start with the cheap water injection tricks. I just found a couple articles talking about the IHI and thought it was interesting.
In reply to singleslammer :
Use E85 . It costs less than 91 octane. I buy it at $1.74 a gallon where most 91/92 octane is about $3.00 a gallon. It has higher octane and because of all the alcohol runs cooler. But you need bigger injectors. At least 60% bigger.
Yeah, plus some way to tune the ECU. That is in the plan but not just yet.
pres589
PowerDork
2/20/18 4:19 p.m.
Is anyone using the IHI twin screw on anything besides the stock motor? I don't think I've heard of such a thing.
Ha, I just had a funny thought; an F2T only without the turbo, replaced by this thing.
singleslammer said:
It only displaces 1.2L BUT it is a twin screw design that runs much cooler and lower mass on the rotors.
From what I remember, twin-screws are more efficient when working hard but less efficient at lower loads. So for street use, a Roots is a better choice. For tearing around a track with your hair on fire, twin. I'm guessing this means a flatter, larger island with a lower peak on the efficiency map for the Roots but that's never been my strong point.
Can you adapt the intercooler the W-body guys are using on their big power builds?
clshore
New Reader
2/20/18 4:52 p.m.
How much boost are you running?
Got an intercooler?
The Eaton Rootes type tends to chew up the air and raise the charge temp a lot over about 5-6 psi.
So a larger one like M112 will often yield less charge heating for the same boost pressure.
You can play with an intercooler and the pulley sizes to fine tune the boost vs charge temp.
In reply to Nick Comstock :
I am sure that I can make my current water to air intercooler could be improved with a bigger pump and larger front heat exchanger.
In reply to Keith Tanner :
The engine has lots of low end now that I have the 4.11 gears (from 3.27 or so). It is a pretty torquey engine to begin with too. I have never gone for all the HP like I want here, so I am not thinking logically either.
In reply to clshore :
I think stock on this engine is 11-12 psi. It is surprisingly high for an M90. It has a air to water system. The only pulley that anyone has made is a $400 lower pulley that adds "35 hp." I bet it would but causes heat soak fast apparently. Mixed with a better cooling system and e85, it might be enough to really help the stock system.
