Carb or efi?

[ftcjimmy]

I have a 1990 Jimmy 1500. Im just getting started and i want to know which is better to run a carb or use the stock fuel injection. I have heard pros and cons about both and im just looking for a little more information. Im using the truck for raising hell around town and some minor off roading. I want power and performance. Thanks.

 

[dirtwarrior17]

All depends on your budget and patience. I am running a 350 hp tbi 355(350 bored .030 over) with the stock harness on my 88 but i added a holley 670 cfm tbi (350$) accel 45 psi inline fuel pump(150$) and soon to come is a prominator(275$) to remapp the fuel and ignition curve. I also have 10:1 pistons, holley projection manifold, muscle car cam, headers, 3" exhaust, k and n and lid, and ported camel humps. Just remember efi is just like carbs as far as making power but you have to mod the computer to get it to run right. A labtop, and a free program called winaldl will let you know what the air/fuel ratio is and the prominator(basically a programable chip) will let you make the changes through the labtop.


might want to head over to www.thirdgen.com

Just about every efi question poster will get directed over there.

 

[mini_mull]

Keep the TBI, and learn how it works. I'm just a novice, but as far as I understand, with a few mods, the TBI can feed up to a 350hp motor. It's more efficient, saves gas, plus won't die on an steep incline like a carb sometimes will. If you're looking for more hp, I haven't run any of their stuff yet, but a lot of guys here recommend www.cfm-tech.com for their TBI performance upgrades. You don't need a custom chip unless you make major changes like high performance engine swap or rebuild with extra goodies inside, but you can run one to optimize performance if you like (most will tell you to go truly custom and not bother with the over-the counter hp chips). I'm planning an HT 383 (340hp, 435ft/lbs torque) crate swap for my '87 5.7L TBI, and it only takes a few extra parts like a vortec TBI manifold, custom chip and some odds and ends to make it work (not cheap all together, but fairly simple, I've been told, and it should still pass emissions). Also, I don't know about CT, but IIRC in some places you need to keep the TBI to be emmissions legal. Finally, before you make any permanant changes to anything on your TBI or anything that might effect your TBI make sure you trust the source of info, there is some less than desirable advice out there online. Do some searches on this forum, and ask questions for anything you can't find in searches, there's some knowledgable guys that know there stuff and will be happy to help you out.

 

[tiger9297]

All depends on your budget and patience. I am running a 350 hp tbi 355(350 bored .030 over) with the stock harness on my 88 but i added a holley 670 cfm tbi (350$) accel 45 psi inline fuel pump(150$) and soon to come is a prominator(275$) to remapp the fuel and ignition curve. I also have 10:1 pistons, holley projection manifold, muscle car cam, headers, 3" exhaust, k and n and lid, and ported camel humps. Just remember efi is just like carbs as far as making power but you have to mod the computer to get it to run right. A labtop, and a free program called winaldl will let you know what the air/fuel ratio is and the prominator(basically a programable chip) will let you make the changes through the labtop.


might want to head over to www.thirdgen.com

Just about every efi question poster will get directed over there.

I have a '90 K5 and I am looking at doing an engine swap too. Is the 670 CFM TBI you are running the Howell system? I have looked at their 670 CFM TBI, and also their Multi-point system. Multi-point is much more expensive though.

 

[dyeager535]

For driveability, consistency, and off-camber ability, TBI has carbs beat hands down, no one that has run both will dispute that.

Every opinion is based on personal preference, it really comes down to what you plan to do, how involved you want to get, and what is important to you.

TBI is a good system, if you plan to keep the motor stock or mildly built, it's a no-brainer in my opinion on what to run. If you want to make it a radical drag-race type motor, then you have to start asking tough questions about time, effort, and cost to make injection work for you.

 

[stizkidz]

http://www.cfm-tech.com/catalog/gm_tbi_performance_parts___accessories_126905_products.htm

Has anyone upgraded their stock TBI system with the parts listed on this page? Their claims sound realistic and those MPG gain figures are quite impressive. Everything listed here minus the adjustable fuel pressure regulator and the cold air intake tube look like solid upgrades. I say that these upgrades combined with a decent header exhaust system and maybe a mild cam should net some decent gains (40-50hp). Anyone have any input?

 

[mini_mull]

Do a search for cfm-tech, and you'll find all the input you need. I'd give you some of my own, but haven't done any of the mods, maybe someone who has will chime in, but if not cfm-tech's stuff has already been discussed many times on old threads and will come up in the search.

 

[dirtwarrior17]

I am running all name brand stuff... never heard of cfm tech until i got to this site.

Here is the setup on my 355....

Holley 670 cfm tbi
accel high pressure fuel pump
holley projection efi manifold
headers
10:1 compression
camel hump heads(ported and polished) about 15 hp better than stock heads
.447 lift .272 duration hydraulic crane cam
k and n
3" single exhaust
soon to come is a prominator

all together i spent about 1100 bucks extra on the upgrades..... heads, compression were on/in the crate motor when i bought it and when i bought my truck it had the 3 inch single exhaust.

It should grunt out in the range of 340-350 hp and 400 ft lbs of torque.

just trying to show you that you don't have to go carb if you want more than 210 hp. the question is can you afford it.