I've had a part idea brewing in my head for a couple of weeks, and I'm to the point where I think it's sound enough that I'm willing to ask for feedback. Since you guys are part of the intended audience I suppose, I can think of nobody better to hear about it from. My thought was to make an adapter plate so you could bolt on a specific late-model OEM intake manifold onto the big block Buick. There's a few advantages to this: You would be able to easily to convert to EFI using widely-available, inexpensive, off-the-shelf OEM fuel system parts and any compatible standalone computer. All the OEM-style sensors could be used, so plugging it into the computer should be a snap too. All the fabrication you'd need is an 02 bung welded on somewhere. With the right throttle body it should be good up to around 500HP without custom porting. That's about where a lot of street cars are built to these days, but there's also a lot more HP to be had with porting and bigger injectors too. Hood clearance would be better than the stock carb/aircleaner combo, and if I made the adapter in aluminum it would be a few pounds lighter. If it worked, would this be something you'd think yourself or the average hobbyist would be interested in? If you could source a good used OEM intake for around $100-150 anywhere in the country, how much would you be willing to pay for an adapter like this? Thanks in advance for the feedback on my crazy idea. - Freed
The real advantage I'd see is the HUGE savings cost of an multiport intake manifold for those that aren't fabricating experts (ME!). I spent well over $700 for the SPX, and another $300 for the throttle body. With what I know now I could MPI a Buick engine with out the SPX conversion (do it myself), and use a carb or something else for the throttle body for a bunch less money, that that's a side note. If an adapter could be made to run a new OEM intake and the price was right, I could see a market for them. Not sure how easy it will be to do though, but don't let that stop you from trying!
Good point, I should have been clearer. I wasn't planning on recycling an OEM computer anyway, but simply using the OEM sensors. Yes it's a port injection manifold. The engines are too different from each other displacement-wise and the firing order would be off for the injectors. You might be able to make it work with an OEM ECU, but it would require a reflash with new fuel curves to handle the different flow characteristics and firing order at the very least, I would suppose. To make up to 500HP you'd ideally go with 40 lb/hr injectors which would require a reflash anyway, so I suppose a definitive answer on whether or not you could force an OEM ECU into service would require research. I was thinking more along the lines of a Megasquirt or another standalone EFI computer. That's something you'd need to buy anyway if you were converting to EFI, but the fact that it would plug in nicely to the sensors would make life a bit easier.
aside from ruining an original Buick intake, could one not just drill bosses in the intake its self to accept injectors? Aftermarket intakes they sell for the Dodge Magnum series of engines come made for Carb'd applications, but have the bosses/spots to drill for injectors. and describe more in detail the adapter. Would it be something sort of like a carb spacer that would fit between the OEM intake and heads, with holes drilled for injectors?
My MPI EFI intake is an SPX TA Performance had injector bungs and fuel rails tig welded on to. I have a performer intake in the basement I plan on at some point drilling an epoxying injector bungs on to and use a Q-jet for a throttle body. I do think there could be a niche market if a modern OEM intake could be bolted on using some adapter spacers, if the price is right. What that price is I don't know, but that's why I threw out there the SPX conversion cost. Of course you have to deal with the water cross over and thermostat housing stuff too.
I don't think there's enough meat there in the original cast iron manifolds to hold the injectors in, even if you machined holes. The adapter plate itself would sit underneath the OEM EFI manifold and bolt to both the Buick heads and the OEM Manifold. It would extend the runners off the OEM EFI manifold to match up with the intake ports on the Buick heads so the injectors would simply plug into the original OEM holes. The OEM intake's runner locations and angles are a surprisingly good match with the Buick heads, even though they were designed 20+ years apart. It would need to be high enough for the coolant passages and far enough back to mount the thermostat in approximately the same location and not interfere with the distributor.
So basically something along this line: View attachment EFIidea.bmp Sorry for the horrific drawing. lol
If I tried this it would be with an LT1 intake. Plenty of flow and looks good too. Plenty of people running big injectors in them for 500 horse applications. Downside is that the dimensions would be a problem. Plus the inlet would be inline with the dizzy.
i dont see why not you could always weld in better bungs or do like ive seen on nailheads and use intake spacers.
I think someone makes adapter plates to fit the Mopar intakes. You could then run their FI intakes like this one: http://www.summitracing.com/parts/EDL-7144/ I started converting an Offy dual quad intake over to FI for fun awhile back but that's been on the back burner for awhile now. I bought the bungs for $6 each and the fuel rail for $10/foot.
I had often wondered how practical it would be to cast a manifold base similar to the GM 1st design TPI that would bolt to the big block Buick, and be designed so that factory runners, plenum, injectors, etc. could be used. Although I must admit that I have not been interested enough to try to mock one up. p
From what I read, TPI had REEEEEALLY long intake runners to make up for the crappy torque the engine would otherwise have had. The cam was pretty tame, and it was choked by all the emissions controls. It was early 80's technology, remember. With runners that long on a built BBB, it wouldn't surprise me if the engine was wheezing for air at around 3500RPM. It starts to have flow issues on a 350 at around 4500RPM, and that would be a significantly lower RPM with a bigger motor. Probably be nice on a rock crawler because it'd have tons of torque on the low-end, but it wouldn't be fun on the dragstrip. Supercharging might make up for that, but then it ceases to be an inexpensive proposition. - Freed
I'm thinking there is a board member who took one of these and modified it to fit a Buick, or built something very similar.
