Buick V6 Megasquirt

[gutless supreme]

Hey -- first post on here, been reading the forum for a few weeks though. EXCELLENT site

Anybody done this? I've searched around here and elsewhere but didn't come up with much. One guy on the MS forums who had done a TBI conversion, another on an off-road forum who had done the same on an old odd-fire 225... that's it.

From browsing through the Megasquirt manual online, it seems as if the factory HEI can be reused as well as most of the stock CCC sensors (I've got an '87 3.8 ). All the other logistics of making it work are out there... I'd do it TBI if that was the only (within reason) way to make it work, but I'd MUUUCH rather use a port injected setup, and that's where things get iffy...

I checked rockauto.com and the very early front-wheel drive ('84-'88) MPFI/SFI V6 intake pattern seems to "match" the carbed V6...

'87 3.8 Carb Intake

'87 3.8 SFI Intake

...EXCEPT that it appears to be reversed, meaning the SFI intake manifold would have to go on the carbed motor backwards - not familiar enough with the SFI motors to know if that would create a clearance issue. I'm assuming the larger hole between the intake ports on the SFI gasket is just an EGR port. The early 3.8 Turbo (EFI) motors use the same exact pattern as the FWD 3.8 as well.

Anyone have any insight into whether this stuff actually fits? I couldn't find any detailed images online and the junkyards where I live don't let you go browsing around anymore. I'd like to start gathering parts and putting stuff together, although it won't be going on the car for awhile... want to get the crappy carb setup, and the rest of the car, running perfectly and straightened out before I tear everything out and start over.

Thanks!
-sean

 

[RegalBegal]

First of all, I'll apologize up front if I seem like an *ss.

Yes, the center ports are EGR. I can't understand why you would think the intake would have to be mounted backward. First of all, the obvious, other than the EGR port size, the gaskets look identical. Secondly, the heads on a given engine ARE THE SAME CASTINGS, just facing each other. So it follows, that turning the manifold backward makes no difference in relation to the heads. It would still mount.

 

[nycutlass]

its ok we forgive you lol ...j/k

First of all, I'll apologize up front if I seem like an *ss.

 

[RegalBegal]

its ok we forgive you lol ...j/k

First of all, I'll apologize up front if I seem like an *ss.

Don't be a dick John!

 

[nycutlass]

 

[gutless supreme]

First of all, I'll apologize up front if I seem like an *ss.

Yes, the center ports are EGR. I can't understand why you would think the intake would have to be mounted backward. First of all, the obvious, other than the EGR port size, the gaskets look identical. Secondly, the heads on a given engine ARE THE SAME CASTINGS, just facing each other. So it follows, that turning the manifold backward makes no difference in relation to the heads. It would still mount.

LOL... it's all good. When I was in elementary school I remember the teacher had a sign up on the wall that said "THERE ARE NO STUPID QUESTIONS, ONLY STUPID ANSWERS" and I have routinely disproved that theory many times over through the years 😳

To be completely honest, I had no idea all sets of heads are identical... so I just learned something new! I've never had an engine with more than one cylinder head apart - BUT, the reason I ASSumed the manifold would need to be mounted backwards (if even possible) was not because of the intake port size/shape (which does look identical either way), but because the mounting points at all 4 corners would appear to be slightly different, unless the SFI manifold & gasket were rotated 180 degrees on the carb heads.

Does that make any sense? I'm kinda confusing myself trying to describe it. Maybe my eyes are just bad... the shape of the manifold and gasket at all four corners is obviously slightly different too, though if the bolts actually do align, I don't think there are any clearance issues.

It would be super easy to figure out if I had an SFI manifold to look at, but any junkyard that's local will rape me for $100+ on one 😢 I can't justify that kind of expensive without being validated by the internet first

 

[liquidh8]

Well, you could always get a turbo buick stock lower and unper plenum, and us the MS. or use the EBL http://www.dynamicefi.com. That has a port injection mode, and also has a ton of support, over on thirdgen.org. I have a turbo 3.8, the LC2. I know they made carbed intakes for it. the heads have their own part numbers. but, you could prolly get a 3.8 intake from a 86-88 lesabre, and make it work. It all depends on your skilss to modify stuff. The reason I say the lesabre, is at least around me, they are a dime a dozen in the pick a part, and you could get the TB, injectors, MAF,and the plenum, all for pretty cheap. I never went the MS route, only because I have been modding factory ECMs/PCMs and am used to that.

 

[RegalBegal]

To be completely honest, I had no idea all sets of heads are identical... so I just learned something new! I've never had an engine with more than one cylinder head apart - BUT, the reason I ASSumed the manifold would need to be mounted backwards (if even possible) was not because of the intake port size/shape (which does look identical either way), but because the mounting points at all 4 corners would appear to be slightly different, unless the SFI manifold & gasket were rotated 180 degrees on the carb heads.

Does that make any sense? I'm kinda confusing myself trying to describe it. Maybe my eyes are just bad... the shape of the manifold and gasket at all four corners is obviously slightly different too, though if the bolts actually do align, I don't think there are any clearance issues.

It would be super easy to figure out if I had an SFI manifold to look at, but any junkyard that's local will rape me for $100+ on one 😢 I can't justify that kind of expensive without being validated by the internet first

If you REALLY look at the gaskets, that square tab on one corner is the same on both. in the second picture, the gasket is rotated 180 degrees. pay close attention to the stamping in the center valley. One vent is wider than the other. now compare the two.




As for converting to FI, Why? For all the cost and aggravation, It's way easier to swap in a small block Chevy.

 

[gutless supreme]

Well, you could always get a turbo buick stock lower and unper plenum, and us the MS. or use the EBL http://www.dynamicefi.com. That has a port injection mode, and also has a ton of support, over on thirdgen.org. I have a turbo 3.8, the LC2. I know they made carbed intakes for it. the heads have their own part numbers. but, you could prolly get a 3.8 intake from a 86-88 lesabre, and make it work. It all depends on your skilss to modify stuff. The reason I say the lesabre, is at least around me, they are a dime a dozen in the pick a part, and you could get the TB, injectors, MAF,and the plenum, all for pretty cheap. I never went the MS route, only because I have been modding factory ECMs/PCMs and am used to that.

Wow I just took a good look around the EBL site and it looks excellent. I'll have to put some time into considering that option instead... seems a lot more "tune-able" on the software end, and I love that it's basically a fully customizable factory GM ECM. MS is less picky about hardware, but this might work a lot better for me.

You're right, Lesabres (and Olds 88s) are plentiful and dime-a-dozen in the scrapyards. That's exactly what I'm hoping to pick up... the turbo V6 piece is probably the most direct fit (check the reply to RegalBegal below) but I'm sure they're also priced accordingly to how rare they are...

BTW I just spent an hour DROOLING over your wagon build thread... completely in awe, can't wait to see it finished!

If you REALLY look at the gaskets, that square tab on one corner is the same on both. in the second picture, the gasket is rotated 180 degrees. pay close attention to the stamping in the center valley. One vent is wider than the other. now compare the two.

Ahhh Ok, you're right... I'm an idiot. I've been looking at the gaskets thinking they were showing the same (rear->front) orientation. I found pictures of a 3.8 teardown online and it confirms they're the same as well. I'm gonna go pick up one of the '86-'87 SFI intakes at the scrapyard next week.

And now after all this unnecessary talk of mounting things "backwards", check out where the throttle body goes on the FWD motors, LOL...

...I didn't take any measurements or anything, but I know without even looking, there won't be enough room between the firewall to fit anything. That probably should have been obvious right off the bat, since it's the same way on 99% of FWD V6s, but somehow slipped my mind. So I guess we'll see if it indeed will go on the other way... even if the mounting points at the corners are somehow different when aligned this way, I guess that really doesn't matter and can be easily fixed as well.

As for converting to FI, Why? For all the cost and aggravation, It's way easier to swap in a small block Chevy.

Plenty of reasons, but most importantly - I don't want a SBC. I'm not trying to build a fast car here, just a DD I can drive a ton of miles and enjoy. Also, I've always really liked the Buick V6 and this one (as well as the car around it) only has a legit 40k miles on it... seems like such a waste to pull it already. The only other thing that's going along with the EFI is a cam, maybe more sometime down the road but that's it for now... so it's not exactly going to cost a fortune.

 

[-83MONTESS-]

Also because everyone and their brothers have SBC's. Keep it original and unique man. Good luck