Port injection or dual tbi???

**buddrow** · 01-26-2014

Hello everyone!

I am outlining my next project. It is a 1972 Buick Skylark with a built 455 and a 4L80E. My delima is this. Buy two affordable gm TBI units and use a 2x4 intake(low rise) or buy a relatively expensiv, by my standards ;), aftermarket throttle throttle body assemly and go port injected. This will be a totally custom setup although there is a port inj manifol available. I know you fine folks here are well versed in custom applications so i hope for some interesting commentary.

Thanks in advance,

Buddrow

**buddrow** · 01-26-2014

Would someone be interested in building a crank trigger set-up for a big block Buick? ;)

**dave w** · 01-26-2014

My "Budget" choice would be the "Port Injection" system. I would use the 16197427 PCM, which can handle the 4L80E transmission controls (cost savings?). I would convert the 16197427 to MPFI mode (same mode as a TPI) (cost savings?). The 16197427 is OBDI with very low cost tuning software / hardware! If the aftermarket Buick port fuel injected intake has a carburetor style mounting for a throttle body, maybe an adapter plate for the Chevy 454 Throttle Body (670 CFM) could be used by removing the injector pod, instead of an aftermarket throttle body (cost savings?).

Depending on where you live, the prices for a used PCM, used wiring harness, and used 454 throttle body might be just what the "Budget" calls for? I'd look for a 1995 454 Suburban / Pickup to get the parts from.

dave w

**dave w** · 01-26-2014

Originally Posted by buddrow

Would someone be interested in building a crank trigger set-up for a big block Buick? ;)

I would sell CAD drawings, so the parts could be made by a machine shop near you.

The prices for "one off" parts will "Stress a Budget"!

dave w

**buddrow** · 01-26-2014

Dave, the bb Buicks like a LOT of air, like 850+cfm when built, that i dont believe the 454 throttle body would supply. I would think dual 350 tbi's on an adapter plate on the dual quad manifold would be sufficient. I have a hard time paying what they want for an aftermarket 4bbl throttle body. Ya im cheap although you could t tell if you look at the cost of building a bb Buick lol. Did i mention I am also thinking DIS? I appreciate and value your input. I have no problem exchanging cash for your time so just lemme know when you get something drawn up for me. ;)

**buddrow** · 01-26-2014

Oh and I have TP5, a burner and have been tuning '7747s for about 6 months with a fair amount of success lol

**dave w** · 01-26-2014

The 454 throttle body could be bored to 54mm, for about 795 CFM.

The attached pictures are my 1st design for a 454 throttle body adapter mounted on a full bore (Holley) bolt pattern dual plane intake. My final design of the 454 throttle body full bore adapter has the volume matched to flow like the bores are 54mm diameter cylinders.

DIS, that would be challenging! Would need to a dual trigger cam / crank configuration.

dave w

**Six_Shooter** · 01-26-2014

In my friend's '71 Cutlass, he has a 46something (IIRC .60 over 455), with a 4L80E, and a home made 4 bbl TBI unit made from two GM TBI units, one is a 454 unit, the other side is a 350 unit. He bored out the 454 side a bit, and it flows over 1180 cfm dry (IIRC). The injectors have been modified to be adjustable.

We are using a 16147060 PCM to run the show. If I was starting from scratch I would use a 16197427 instead, since it has a little more support for tuning and home brewed modifications.

His car puts out over 500 HP and 600 ft/lbs to the wheels.

I'm attaching some pictures of revision #9 I think it is. There have been several of these made by the owner. He currently has two of them, this one on his Olds, and another with a different fuel system in his GF's Caprice that is also Olds powered.

**Six_Shooter** · 01-26-2014

Originally Posted by dave w

The 454 throttle body could be bored to 54mm, for about 795 CFM.

The attached pictures are my 1st design for a 454 throttle body adapter mounted on a full bore (Holley) bolt pattern dual plane intake. My final design of the 454 throttle body full bore adapter has the volume matched to flow like the bores are 54mm diameter cylinders.

DIS, that would be challenging! Would need to a dual trigger cam / crank configuration.

dave w

DIS would not be that difficult. Using the Northstar DIS it would be a single wheel solution, with some tweaking of settings in the BIN.

**EagleMark** · 01-26-2014

If you have access to the dual quad intake? Then I'd use twin TBI throttle bodys with TBI adapters and have the machining done to add MPFI injectors and fuel rails.

**lionelhutz** · 01-27-2014

Originally Posted by EagleMark

If you have access to the dual quad intake? Then I'd use twin TBI throttle bodys with TBI adapters and have the machining done to add MPFI injectors and fuel rails.

That's exactly what I was thinking as I read the thread. Use one TPS and parallel up the IAC motors.

**buddrow** · 01-27-2014

Since i dont have a tig welder nor the faith in welders in my area to do it right ill have to pass on the frankenbody for now although i do dig it.

Six, do u have that link handy for he nothstar bit? I remember seeing it and it piqued my interest.

Mark, i will likely go the dual qual intake route with port injection given the advice and personal interest in the subject.

Keep the comments coming. This will likely be a year long project due to time constraints so bear with me on pics, progress and whatnot.

**buddrow** · 01-27-2014

Originally Posted by lionelhutz

That's exactly what I was thinking as I read the thread. Use one TPS and parallel up the IAC motors.

Can the '7427 drive dual IACs?

**EagleMark** · 01-27-2014

Originally Posted by buddrow

Can the '7427 drive dual IACs?

No need too! gregs78cam runs dual TBI with one IAC. Takes a little bit of work when vehicle is fully warmed up and driven, then adust throttle plates so IAC has some control, like 20 counts.