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Discussion Starter · #1 ·
Hey guys, I have been considering some type of EFI for my K5 Blazer for sometime. Well this weekend I took it to the beach with my girlfriend and got really horrible mpg both directions. The engine is a fresh, mild 355 with L98 iron replacement heads, 9.0:1 CR and a Summit 1103 cam (.442/.465" lift, 214/224 [email protected]", 112 LSA), Performer RPM intake and currently a Edelbrock 600 cfm carb. The truck has 4.11 gears, 33" tall tires, and a 700R-4 tranny and turns 2000 RPM while cruising at 65 mpg.

I did a search and decided on a Commander 950 EFI TBI setup, but the question I have is what size I should get since I am out looking for mpg. Some local guy says I can go wrong even with the 900 cfm unit since the ECU won't give the engine more gas than it needs. I am no expert but that doesn't sound right.

I considered the cheapest 670 cfm 2bbl setup but I remembered that all things being equal a 4bbl carb will give better mpg than a 2bbl carb because you aren't into the pedal as much. Does that still apply to TBI's?

Here are the cfm offered:

650 cfm 4bbl
670 cfm 2bbl
700 cfm 4bbl
900 cfm 4bbl


I have a laptop and was planning on buying a wideband o2 setup to tune.

Any help is thanked in advance.
 

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I would go with the 900cfm cause you can put the lower flow injectors in it and be just fine. and if you decide to go bigger you have that advantage you will loose a lil low end cause the bigger cfm will work better up high. just my 2 cents
 

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Discussion Starter · #3 ·
Anyone else?
 
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