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 I think I might actually go with my M62 instead of an M90 top swap

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Name : Corey
Age : 27
Location : JMU virginia
Joined : 2011-07-25
Post Count : 569
Merit : 2

PostSubject: I think I might actually go with my M62 instead of an M90 top swap   Thu Dec 20, 2012 10:41 pm

So, many people would call me retarded for this, but I'm going to be taking Industrial Welding Fundamentals I and Metalworking fundamentals I classes very soon. The fuel mileage in my engine has been going to shit for a long time now, and I'm pretty sure it's because of the fact I need to change my fluids and more importantly, last time I cleaned my throttle body, there was a good amount of thick sludge coming out. You guys might say "but hey that's kinda normal for a car with 212k miles" well, my throttle body is only 49mm, and you guys with the supercharged L67 get a 62mm thottle body. It would affect an L67 a lot less.

Anyway, I took out the supercharger from Parts Buick today, and the Lower intake manifold off the blown L36 in the shed. The LIM needs some SERIOUS cleaning and I'm gunna get a giant plastic tub and soak the LIM and supercharger parts in the tub with diesel in it. Diesel is one of the best solvents and that alone will be almost as good as hot tanking it if I leave it soaking for a few days. I'm also going to port and polish the LIM. New gasket set is available in stock nearby for like $40.

Here's the supercharger and the LIM next to each other. I already have a decently thought out plan but I don't know everything about how the supercharger works yet, and I'm no master tech either.

My plan so far? Wait until I learn how to weld pretty well in the next couple months. I'm going to take the LIM out of parts buick soon. I will take the parts buick LIM, and cut off the very top of it and fabricate myself a spacer and interface between the L36 LIM and the supercharger. I will need thick aluminum plates and I will trace the shape of my plenum and cut that out in aluminim and weld some thick aluminum sheet metal from the base of that to the plate I cut off the parts buick LIM top piece. This space/interconnect piece will do a few things. It will align the shorter M62 to my engine belts, It will serve as an interconnect and mounting system along with me trying to get the bracket tension thingy off parts buick if that fits, and also I plan on getting the heatercore out of parts buick and using that as a water- air intercooler. I have a decent amount of things I need to make this happen already, and just need some welding equipment, a new engine belt, the aluminum plates, and a new rotary tool because mine broke

Anyway, people have said it's a bad idea for this, that and ten other reasons, but having the M62 already saves me a lot of money. A 75mm throttle body is a huge upgrade for me, and even a good upgrade for you guys and that alone saves me like $500. Iv'e been thinking about my fuel mileage issue for a while, and I'm like maybe 17 mpg highway right now and even less in the city. It's getting pretty bad. I was about to take apart my entire manifold and throttle body today, but then I just looked at my manifold and realized how much I hate it and how much it sucks. Then I remembered something I came across a while ago online. A guy with a pontiac bonneville L36 put in the L67 throttle body, ported his LIM and exhaust manifold with no other mods other than an intake and he gained 10% volumetric efficiency. I'm thinking I'd be seeing slightly better with an even bigger 75mm throttle body. The reason this interests me is because the M62 spools way faster than an M90 which would get me peak torque faster. Not good for my transmission if I plan on adding huge power but I'm not. Anyway I should be seeing way better fuel economy because the M62 has less parasitic effect on the engine than an M90 as well. This just as much about fuel economy as making my car go fast.

It's not going to get done overnight so I have a lot of time to think about it, but I think it's totally doable if I get some help here and there like knowing exactly how the M62 works and what sensors Id need replaced and whatnot. The good thing is I can use the extra engine as a mock up and my daily driver isn't affected until the day I install.

One thing I noticed is that after physically holding the LIM, it seems incredibly simple to do a mild porting job. Also Iv'e worked with grinding and shaping metal here and there with random projects so it won't be too hard.


I think I'd also weld an additional thick aluminum plate over my LIM to basically act as a permanent HV inset, make the two holes for the 10mm bolts and simply plug those holes with two small rubber corks afterwords. That should help the manifold flow a lot better too.
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Name : Andrew
Age : 33
Location : Ontario, Canada
Joined : 2008-01-14
Post Count : 1947
Merit : 122

PostSubject: Re: I think I might actually go with my M62 instead of an M90 top swap   Fri Dec 21, 2012 11:13 am

Quote :
Anyway I should be seeing way better fuel economy because the M62 has less parasitic effect on the engine than an M90 as well.

You have that backwards.(Unless you always stay out of boost, but in that case why have the SC?) Under boost the m62 has more parasitic drag since it needs to spin faster to make the same boost. Add to that your losses by it being a much less efficient air pump by design and putting out boatloads of heat (Which your higher compression ratio won't respond well to.)

On a smaller engine, sure the m62 would have less parasitic drag than the m90, but the 3800 is already pushing it to outer limits of its designed efficiency range. A trait of Eaton blowers is that once you step out of that range the parasitic loss increases almost exponentially. (and I know this all too well running one with a 2.4" pulley.) The m90 is the better sized blower for both power and fuel mileage on the 3800.

Oh, and the HV insert works on a NA engine by shorting the length of the intake runners for more high RPM breathing. You would also want to throw one in with a turbo since it gets rid of the plastic intake runners that just cause extra resistance on forced induction. You won't have those since you are replacing your entire upper plenum. No point in trying to make a HV insert at that point since runner length tuning goes out the window with FI. What you do need to worry about though is plenum volume under the SC. We are talking about the large open bit of air that you will notice in any l67 LIM. There is a specific volume that works best and IIRC its around 1.5 liters excluding your intake runners. This gives the engine its initial breath of air when stabbing the throttle just before the SC really begins to do its thing. Get the volume too small and the engine will run like a bag of hammers, get it too large and you will be chasing down vacuum problems for the rest of your life.

As I've mentioned to you before, "Anything is easy if you say it fast enough." There is a huge amount you are missing about what this project actually involves, but learning that only comes with experience. And the only way to get experience is to try it.

So best of luck to you on this project.

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Name : Greg
Age : 25
Location : Wisconsin
Joined : 2011-02-07
Post Count : 590
Merit : 17

PostSubject: Re: I think I might actually go with my M62 instead of an M90 top swap   Fri Dec 21, 2012 11:28 am

If for some reason you decide to go the m90 route, i have seen many of m90's on craigslist for about 100 dollars or some even less.
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I think I might actually go with my M62 instead of an M90 top swap
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