All Big Six Anyone know this supercharger project?
- Thread starter PSIG
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Not familular, however it looks like the blower from the Holden/Buick v6, if it is, it would be way too small for a 300ci engine. the Jack shaft idea as I understand it is to get the pulleys to line up, there is no need to have the blower mounted centrally over the engine, you can move it back or forward to make the drives line up with little or no detriment to torque. In this case they have elected to use a stock Offy manifold and made an adapter plate. As they say there is more than one way to skin a cat!
PSIG
Famous Member
Agreed. The M90 in the photo is common in the USA on V6 setups, and used are pretty cheap on auction sites. This was an option on another build that went another direction, so I have the Eaton M112 supercharger from a Ford Lightning still on the shelf. While it has an overdrive pulley currently, that's easy to change, and would be the schitt for a good 300 fit.
Eaton M112 top-feed with a $100 custom EFI board for boost bypass, ignition, fuel control, etc:
Eaton M112 top-feed with a $100 custom EFI board for boost bypass, ignition, fuel control, etc:
What is the limiting speed on these blowers? Even at 112ci per rev, its probably a bit small for a 300ci six, although having said that the 300 sixes VE is pretty low in stock trim.
Judging by the delta T its adiabatic efficiency isnt too good. Probably need to spin it to 10k or so, so thats a ratio of around 2:1. 40bhp @ 10000rpm for 10psi tells me that not normal belt drive is going to do it, toothed belt time.
Buick V6 is 3.8litres and will have much better breathing than the ford six. The blower would be running fairly fast even on the buick engine, going 30% above that may put it above its limit. From memory the buick blower is 1.5litres per rev. The 4.9 ford passes (assume 100% ve here) passes 2.5litres per rev, to get any boost the blower needs to run 2.5/1.5 faster then the crank. To get 10psi for instance its got to go 25/15 faster again, so now we are around 3 times crank speed, this is a gross estimate and makes no allowance for any losses. Basicly the blower would be right at its limit at 4500rpm crank speed. QED, its a bit small for the 4.9!
PSIG
Famous Member
The M90 isn't far behind for drive power requirement. The m90 has the 6-rib and has wide 8-rib pulleys available, while the M112 is stock with the wide belt, so should be fine. It's going to take a ratio of power to drive it, and heat is expected for a helix compressor like this - always an issue with positive-displacement superchargers. Weigh the pros and cons. 
I estimated 76% VE at peak HP (stock cam) on the 4.9L. I wouldn't do the M90 myself for more than a few psi, but the M112 is looking good for useful fit. It would need to make more outlet pressure to hit manifold boost on a 4.9, and heat that goes with it, but if your goals are fun I think it would deliver that, IMO. It's all about the goals.
[EDIT] I ran some numbers, and if they're correct
, it'll do 430 hp at 5000 rpm with 15 PSIG boost at just over 600 cfm inlet. To get there would be just under 11k shaft speed with a 2.2 ratio drive, so assuming a 6.75" crank pulley, that's a 3" blower pulley (common). 15 pounds at 180°F is a bit much for pump gas of course, and without adding a bulky under-cooler (like Mustangs and lightnings), perhaps inlet water injection could cool the blower and air to get there. Hmm. 
I estimated 76% VE at peak HP (stock cam) on the 4.9L. I wouldn't do the M90 myself for more than a few psi, but the M112 is looking good for useful fit. It would need to make more outlet pressure to hit manifold boost on a 4.9, and heat that goes with it, but if your goals are fun I think it would deliver that, IMO. It's all about the goals.
[EDIT] I ran some numbers, and if they're correct
, it'll do 430 hp at 5000 rpm with 15 PSIG boost at just over 600 cfm inlet. To get there would be just under 11k shaft speed with a 2.2 ratio drive, so assuming a 6.75" crank pulley, that's a 3" blower pulley (common). 15 pounds at 180°F is a bit much for pump gas of course, and without adding a bulky under-cooler (like Mustangs and lightnings), perhaps inlet water injection could cool the blower and air to get there. Hmm.
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Firepower354
Famous Member
I think the M90 chart posted, and the rest on RBRacing.com, are for the earlier Gen3, and the 5 runs cooler and more efficiently, plus the draw-through fuel evaporation should reduce the temp rise quite a bit. More so with E85. Sure, a 112 or 122 would do "better" but the Buick started with a M62, and several tests with the 90 have made decent power.
www.onallcylinders.com
When Bigger is Better: 4.8L vs. 5.3L M90 Blower Test
Does more boost automatically result in more power? Engine expert Richard Holdener explores the science of boost in this comparison test.
www.onallcylinders.com
I get around 11psig at those rpms and 76%ve on the engine, that wont give those power levels. 85c temp is probably low.The M90 isn't far behind for drive power requirement. The m90 has the 6-rib and has wide 8-rib pulleys available, while the M112 is stock with the wide belt, so should be fine. It's going to take a ratio of power to drive it, and heat is expected for a helix compressor like this - always an issue with positive-displacement superchargers. Weigh the pros and cons.
I estimated 76% VE at peak HP (stock cam) on the 4.9L. I wouldn't do the M90 myself for more than a few psi, but the M112 is looking good for useful fit. It would need to make more outlet pressure to hit manifold boost on a 4.9, and heat that goes with it, but if your goals are fun I think it would deliver that, IMO. It's all about the goals.
[EDIT] I ran some numbers, and if they're correct
PSIG
Famous Member
It looks like over 190°F (±90°C-ish) from the charts. OK, by anybody's math, it sounds like somewhere between fun and funner. 
I have the M112, fuel system and ignition if someone has the 300, time and willingness. Wanting to stretch it safely, I'd do EFI and digital ignition. Adapting to the stock EFI lower would be the easy path if there's room, or piping from the far side to the upper inlet.
I have the M112, fuel system and ignition if someone has the 300, time and willingness. Wanting to stretch it safely, I'd do EFI and digital ignition. Adapting to the stock EFI lower would be the easy path if there's room, or piping from the far side to the upper inlet.
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FWIW here's the Aussiespeed blower manifold. This gives you lumps for injectors that the Offy C is missing.
