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454 pickup needs more power

475 Views 8 Replies 7 Participants Last post by  Moosecountry
1991 long box work truck. Im wondering cheap upgrades?
It will get exhaust first. Anyone know what the factory F.I. flows?
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The BBC TBI flows pretty well, but the problem is that the ECM won't adapt for changes very well. Maybe look to a standalone ECM? The low compression begs for forced induction. Compare the cost of a supercharger/turbo and ECM to the cost of heads to get compression up along with the potential intake/cam/gears/etc needed to match it.
 

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Discussion Starter · #5 ·
Thank you Curtis . Im not well educated in F.I. The low cr is not something thats easy to over come. I know nothing about changing to a stand alone ecm? I dont see the engine being worth the weekend for a Camshaft change. I bought it as a complete put to work pick up and it functions well as is. My 99 F-350 7.3 does everything better I just wanted to bring it up to a closer speed. The 2" single exhaust will be changed out as soon as I heal from a little oopsy I had at work (slipped a disc, and not in the truck)
 

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I believe Megasquirt sells a tunable ECM in a version to use on most GM vehicles, but it’s not a cheap “fix”. If you had long term hot rod plans for the engine it might be worth it, but too expensive for a one time fix.
 

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Yes, exhaust will be a good place to start. As big and free flowing as you can get by with and still pass state inspection, assuming that's a consideration.

What's the rear axle ratio? If less than 4.xx, a step or two lower (higher numerically) would also help.
 

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The 454 TBI flows about 640 CFM it is just a little smaller than the 670 CFM Holley. However fuel is computer managed. As a result what can be done to hop up this engine is very limited before you're into reprogramming the computer.

Transmission if an automatic will be the 4L80E it needs a computer to operate so changes to the engine say like TBI to carb and ignition to HEI require the computer be fed tach, throttle position and Manifold Absolute Pressure (MAP) data is it does now in order to modulate shift pressure.

So changes are possible but must be planned out.

Cam can be increased to an intake timing closely around 200 degrees at .050 lift and the LSA is kept not less than 110 degrees, here bigger is better. TheTBI computer will most often adjust to this if your factory O2 sensor is working.

Big tube long primary headers are very effective as is a 3 inch dual exhaust system.

Compression ratio on this engine is miserably low but nothing much can be done without deep surgery. Here the bore diameter of these engines really works against you where detonation is concerned. Aside from aluminum heads compression creases must be carefully orchestrated with regard to piston selection and deck clearances.

Bogie
 

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Discussion Starter · #9 ·
Thanks Bogie 640 cfm is plenty for what I need. If the F.I. system is difficult to tune I will convert the exhaust to dual 2 1/2". Headers here are very expensive .I bought the truck for 2800 including a tool rack, tool box and misc hand tools. No rust, super solid but everything has been loaded overhand so its not going to be a hotrod. My kids are going to spray bomb artwork on it. A trend thats popular here
 
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