Fluid Dynamics/boost airflow

[a_kelley]

Here's a question.. I've got a m90 I'm planning to top mount on a 4.0 manifold.. question is how important is having a straight smooth path for air to travel?

As you can see, the blower outlet is off to the left of the intake on the manifold. I can enlarge the opening in the intake to be close to 2.5" offset but at present, it is about 4". Would it matter much if I just made a square adapter and port it versus sloping the ends & porting? (I suppose I could build it square but and insert a piece sloping inside) Ifound a pic of a kit adapter for top mount and it's pretty square.. I'd imagine porting the opening would have more effect on airflow than sloped ends.. for reference..

It will happen and I have done research on fueling, methanol injection, & etc, so I know what's involved.. planning on 8 psi but hoping to repulley it to get about 10-12..

 

[braxton357]

Obviously your restriction will be the intake manifold-- being that this isn't all "all out" application pretty much any transition you make will work fine. That blower will also work at any angle so if plumbing it on it's side is easier then do it. 12 psi with an m90 and a 4.0 will be pushing 190* air into the engine, how are you going to control the timing?

 

[a_kelley]

I'm going to chip the factory ECM. Methanol injection will drop the IAT a little. Chip it, mega squirt or SS FTC piggy back.. chip the original ecm would be the best option.. plus that would allow remapping it for the 2 bar map and 30lb injectors.. or whatever they are. Might be 34 lb, they came off the 3.8. (score, same physical size and electrical but about the right flow)

Side mount would be tits but it's too tight at the back end by the booster and firewall unless I can get a custom intake made..

Images shamelessly ripped from the internet somewhere.

 

[a_kelley]

Maybe I could fit it on a 45* towards the driver side but doubt that it would be worth the aggravation.. looking for simple mechanical mounting and routing.. top mount didn't seem to give as much wrap on power steering as factory but after looking again, seems about right

 

[a_kelley]

Obviously your restriction will be the intake manifold-- being that this is all "all out" application pretty much any transition you make will work fine. That blower will also work at any angle so if plumbing it on it's side is easier then do it. 12 psi with an m90 and a 4.0 will be pushing 190* air into the engine, how are you going to control the timing?

That's what I was thinking about on the restrictions.. just wanted confirmation.. what do you mean by "all out" application? As in as much as it will deliver?

 

[braxton357]

Meant to say it "isn't" an all-out as much performance as you can get application. Unless you're also doing Pistons, heads, blower cam etc. Sounds like you've got a solid plan, hopefully the stock pulley will line up with your belt and still work like you're planning. Then you're just down to throttle body mounting and tuning. What are your plans with the jeep?

 

[a_kelley]

Well I've actually got two m90s. One is for my Wrangler yj project and was hoping to do it first before my DD.. but I'm a sucker for a challenge.. if I make it simple to mount, I should be able to get it ready to drop in and then jump on tuning it on the weekend.. and if I have to I can take a extra day or two tuning, even if it kills a work day. The yj will be a stroker with the blower, so it will make more difference on it, but won't see as much boost on it configured the same as a 4.0.. throttle body is off a 4.3, sensors and iac match stock xj stuff.. but it's a 2.75 throat.. oh and I guess I'll need to add a wideband o2. (Which chipping the original computer will let me hook up and use as well as for logging)

(I've Only been researching/toying with the idea for about a year)

 

[Croatan_Kid]

Air likes to travel in a nice, smooth, radius. Of course...if it's being forced, it'll pretty much just go on in there

 

[Fabrik8]

That factory manifold gives me nightmares. Clearly designed for tight packaging and nothing else.

Are there other manifolds available for that engine?

 

[a_kelley]

That factory manifold gives me nightmares. Clearly designed for tight packaging and nothing else.

Are there other manifolds available for that engine?

Yes, for a few thousand you can get the side mount manifold with the charger... Which is based on the factory manifold.

 

[NCJeeplover]

What if you milled the top of the plenum off of the stock intake and then welded a 1/4" piece of aluminum in its place? Then you would be able to move the blower forward or back to fit the belt and your transition would be better.

 

[a_kelley]

That's about what I was thinking of doing, except I don't know who would weld aluminum to cast aluminum and how much.. and it needs to be raised up about two inches to clear the fuel rail.

 

[braxton357]

That's about what I was thinking of doing, except I don't know who would weld aluminum to cast aluminum and how much.. and it needs to be raised up about two inches to clear the fuel rail.

What's your timeline? I would be willing to help you out but am pretty busy for the foreseeable future.

 

[Fabrik8]

That's about what I was thinking of doing, except I don't know who would weld aluminum to cast aluminum and how much.. and it needs to be raised up about two inches to clear the fuel rail.

That's actually done all the time for intake manifold modification. It's not really a structural part at all, so the normal problems with welding cast to plate aren't as important. People add/change injector boss locations, add a plenum box, larger throttle body flange, etc., for different engines.

The air path to those two inner runners though (3 and 4?)... Ugh...

 

[Mac5005]

That's about what I was thinking of doing, except I don't know who would weld aluminum to cast aluminum and how much.. and it needs to be raised up about two inches to clear the fuel rail.

David Farlow at boostfab.

If he can’t I’ve got a local guy that can also. Pm me if you need contact info.

Does it all the time for turbo stuff.