[BILTIT]

Has anyone tried to use a 454TBI unit on a pontiac? Would need a custom chip im sure but would seem to be an easy conversion otherwise. Using Megasquirt would make it pretty painless.

[PONTIAC LARRY]

I always wanted to try one on a mild 455 with like 6x-8's and a Summit 2802 cam..lots of vacuum , might work with a stock computer chip. Surely would with like an 068 cam... It would be a great setup on a land barge cruiser

[BILTIT]

Yup, i plan on putting a 400 into my 80 chev silverado. TBI would make it even better.

[ponjohn]

I proposed this on PZ using a marine MFI upper intake. You would then have to fab a lower intake to use the upper.

The issue with the EFI intakes sold today for the poncho is there is not enough plenum area. I consulted with two custom intake companies and they concurred that the plenum area is very important for an N/A application.

An example of a good efi intake with plenum area is Jack Blume's. Here is a picture.

[BILTIT]

Ponjohn- i can understand with multiport injection then a custom intake would work best but for a throttle body unit, all we can do is put it on a carb intake.

Ex. I look at my 93 chev 1 ton with a TBI 350, intake looks like a standard carb intake.

Why couldnt a person swap a TBI unit off a chevy on to a pontiac intake and have a chip burnt or use megasquirt. Seems too easy to be true. I guess most people just take the extra step and go multiport.

[6 Grrrs]

My 1990 454SS (last year for GenIV in a production vehicle) came from the factory with a Qjet (spreadbore) intake manifold with a TBI spacer attached to it. In 1991 they went with a TBI intake on the Gen V motors.

[Mr_GTO]

Originally Posted by ponjohn

I proposed this on PZ using a marine MFI upper intake. You would then have to fab a lower intake to use the upper.

The issue with the EFI intakes sold today for the poncho is there is not enough plenum area. I consulted with two custom intake companies and they concurred that the plenum area is very important for an N/A application.

An example of a good efi intake with plenum area is Jack Blume's. Here is a picture.

Not enough plenum area? Wouldn't that be the case for carb'd versions as well? All EFI intakes are just modified carb intakes but instead of flowing fuel and air through the intake it just flows air and fuel is introduced right into the head.

[PONTIAC LARRY]

We are just talking about a simple TBI spacer/adapter that is readily available cheap and fits a standard 4 barrel intake.. ie: a regular Performer intake would be perfect.
If the vacuum readings are the same or at least very close to the stock 454 or 350 application (depending on which TBI and computer your using) , there should be no reason at all to have to get a custom chip. A peanut port 454 and a stock head Pont 455 or 400 should also be very similar on demands for air/fuel mixture.. lean and mean !!! TORQUEY and great cold starts and driveability too... Just use a stock or near stock camshaft.. 400 with a 066 or 067 cam...very good match...

[mudbird]

Well for what it is worth... My daily driver is a 93 k3500 with a TBI 454 and it usually gets about 10 mpg. (empty or hauling my 69 bird on a trailer or my sled trailer makes no difference) I like the TBI system's they are cheap and easy to maintain but do not get that great of mpg in my op. I often say that my 850 demon in the bird uses less gas, certainly at idle but it is a heavy truck.

I lurk at the thirdgen.org boards and they have a great TBI forum with some great modified TBI set ups. They often use a dual plane with an adapter and use the 454 throttlebody when they need more air in a small block, The holley ones are considered not much gain for the money. Lots of good info there if you are into this idea.

I think it would be kind of cool on a Pontiac motor with a 4l80 and Flash EBL from Dynamic EFI in the computer for programing. It may be cheap to do but I do not think the mpg would be much better than a good carb set up. I do like the TBI and think of them as a speed density two barrel

[BILTIT]

Mudbird, good info thanks.

I have also seen many guys run the 454TBI on modified smallblocks for the increased air/fuel flow.

My thoughts: Up here we have some very cold days (-40C/F) and my automatic choke Q-jet on my 350sbc ('80 chev 3/4T) never works worth a crap. It is a bear to start even when plugged in. I am planning a 400P swap into this truck and think the TBI would be sooooooooo much nicer for cold start and overall driveability. The truck is lifted 6'', 4.56 gears and running 36'' tires: therefore, gas mileage really doesnt matter.

Just seems like an easy swap without getting into too many money items needed like the multiport setup.

[mudbird]

I do agree, the cold start is much better.
You may be able to get one to work with the stock programing. I would make sure to run the correct fuel pump for the application as I hear they are higher than the 305/350 motors.

[6 Grrrs]

http://www.tbichips.com/ can burn you a chip easily.

He did one for me a few years ago when I put a TBI 454 into a 350 dually that originally came with a 4L80E. It took a few tries, but he was easy to work with & willing to make things correct. I put a cam/intake/headers & full 3" exhaust on that truck & we had issues with getting good economy & performance. The best towing economy we could get without losing performance was 8mpg. That was if you kept your foot out of it. It would also smoke the duallys thru 2nd gear. We got the towing mileage up to 10, but the truck felt kinda sluggish.

[PONTIAC LARRY]

My dads old 93 Suburban 1500 2wd with 275,000+ miles pulled of 18 mpg hwy with original stock 350 stuff when I took a trip to Houston a while back..

[6 Grrrs]

1/2 ton 2wd 5.7L is very different from a 454 dually

My 100% completely stock 1990 454SS with T400 & 3.73s only got a best of 13mpg with my then girlfriend driving it. Usually I got 8-10 mpg on the highway & 8 around town.

Now it gets 17mpg on the highway & about 10mpg around town, with 398 whp.

[BILTIT]

http://howellefi.com/customer/produc...cat=272&page=1

This might even work better!

[boater bill]

I converted my Jeep 258 to a GM 4.3 TBI with an Offy intake several years ago. I got all of the wiring, sensors, TBI etc from http://www.turbocity.com/
I am sure they can help with your conversion. You will add an O2 sensor, lock out all of the vacuum and mechanical advance, different fuel pump, etc.

Good luck

[amcmike]

Been a while since I've perused this site, but somewhere there was information on burning your own chips. Of course, you still have to know how to tune it.

http://www.diy-efi.org/

[Jack Blum]

Originally Posted by ponjohn

I proposed this on PZ using a marine MFI upper intake. You would then have to fab a lower intake to use the upper.

The issue with the EFI intakes sold today for the poncho is there is not enough plenum area. I consulted with two custom intake companies and they concurred that the plenum area is very important for an N/A application.

An example of a good efi intake with plenum area is Jack Blume's. Here is a picture.

Yea, Bill PMDRACER and I designed that and Bill built it back in 1995. We got to talk to a couple of guys that design EFI manifolds for a living. There best advice was 1 cubic inch for each cube in the motor in the plenum. And the runners as straight as possible with 1% per inch minimum taper. This helps keep the air from swirling and also speeds it up. The problem with using most carburetor manifolds is there is no plenum and usually no taper. But if your just doing a street car it usually works fine.

[jonathonar89]

Sorry to bring up an old thread but I thought it'd be better to revive it rather than start a new one. I haven't posted in a while and my project has been slow-moving/changing the past couple years but I've been making moves towards building this setup on my Pontiac 400. I hope to be more finalized with the build this upcoming year.

-454 TBI from late 80's truck
-Holley Street Dominator intake
-'81 Turbo 301 Distributor (computer controlled Pontiac HEI)
-Megasquirt 2 Carb-To-EFI kit

[trailwing]

I think you will need some tuning help and perhaps a wideband or self learning computer. I screwed around with a 350 in my Jeep for months... Edelbrock intake, Holley intake, Holley throttle body, 350 throttle body, 455 GM throttle body... the stock computer is stupid and difficult to tune by yourself. Without a dyno, it's difficult to simulate all the load and rpm conditions required to make it run right.