TBI vs PFI

[x ReAcT x]

Throttle body injection sprays directly into the throttle body right? I know it sounds silly that im even asking this but isnt that practically the same as Port Fuel Injection? Whats with the different names? marketing?

[Lobie]

Port has an injector for each cylinder which sprays right before the valve.
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[x ReAcT x]

Originally Posted by Lobie

Port has an injector for each cylinder which sprays right before the valve.
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Making it more efficient im assuming? In your opinion do you think its comparable to EFI in the LS engines?

[DirtyLarry]

Originally Posted by x ReAcT x

Making it more efficient im assuming? In your opinion do you think its comparable to EFI in the LS engines?

Dude, you are wearing us out lately. Just razzing you! We’re always glad to help educate newbies.

TBI – Throttle Body Injection (1987 – 1995 5.7 through 7.4L) ….similar to a carburetor where fuel delivery is squirted in the mouth of the intake manifold but TBI is much more reliable and precise fuel control over any carburetor. TBI is much better than carburetors!

MPFI (SFI) – (1996 to current 5.7L through 8.1L) Multi-Port Fuel Injection but in the GM world, they called it Sequential Fuel Injection where each injector is fired individually in the engine firing order. Much better than TBI!

Direct Injection – (coming in 2014 5.?L through 7.?L. GM is already using DI on 3.6L V6 engines) The fuel injectors are mounted in the cylinder head beneath the intake ports and spray fuel directly into the combustion chamber fired individually in the engine firing order, just like a modern diesel engine. Much better than MPFI!! Direct Injection is a huge jump in technology and performance almost like going from 1986 carburation days to the 1987 TBI days. DI is a major milestone in GM gasoline engine history and will be the next big thing for engine swappers in the years to come. The performance cannot be matched by any previous fuel injected engine. DI is the shizzle...you'all just wait and see!

An LS engine is what you could consider port fuel injection, but in GM Powertrain lingo it would actually be SFI and yes it is more efficient and produces much more performance. It kills me to see people take a LS engine and spend a pile of money on a controller and harness to run the distributorless ignition only to throw a toilet carburetor on top. I don’t get that. For a tiny bit more they could have fuel injection and a heck of a lot more performance and durability.

[x ReAcT x]

Yea i appreciate you guys dealing with my silly questions hahah I finally figured out the engine im getting so this will be the last one of those EFI questions. I dont know what i would do without all the help

[x ReAcT x]

I totally agree with the whole carburated ls nonsense

[Billett]

Originally Posted by DirtyLarry

It kills me to see people take a LS engine and spend a pile of money on a controller and harness to run the distributorless ignition only to throw a toilet carburetor on top. I don’t get that. For a tiny bit more they could have fuel injection and a heck of a lot more performance and durability.

[x ReAcT x]

Hahaha PREACH IT! i like that

[slinginrods]

Just to Clarify ,the 86-92 tip found on camaros and vetoes were batch fired,meaning two injectors at once.they didnt go to sequential fi till the lt1 or gen 3 small block Chevy came out in vetted in 92 and the camaro in 93.tpi was marginal at best.ls engines or gen 3&4.small block Chevy is sequential.there was also a CPI or central fuel injection on s series blazer in the 90s that used a central high pressure injector that fed cylinders individually through poppet valves and nylon tubing. Dfi is not new it has been around forever ,it's very efficient but in gasoline apps it's prone to carbon build up.as for carbs on ls engines ,it has been proven that a carb on a stock ls can make more power than the fi ,but you are right the drivability will always be better with fi.to each his own.i have built them both ways.ls is miles ahead of any 1st gen sbc.no matter what induction you use.
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[clinebarger]

Originally Posted by slinginrods

Just to Clarify ,the 86-92 tip found on camaros and vetoes were batch fired,meaning two injectors at once.they didnt go to sequential fi till the lt1 or gen 3 small block Chevy came out in vetted in 92 and the camaro in 93.tpi was marginal at best.ls engines or gen 3&4.small block Chevy is sequential.there was also a CPI or central fuel injection on s series blazer in the 90s that used a central high pressure injector that fed cylinders individually through poppet valves and nylon tubing. Dfi is not new it has been around forever ,it's very efficient but in gasoline apps it's prone to carbon build up.as for carbs on ls engines ,it has been proven that a carb on a stock ls can make more power than the fi ,but you are right the drivability will always be better with fi.to each his own.i have built them both ways.ls is miles ahead of any 1st gen sbc.no matter what induction you use.
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92 & 93 LT1's are "batch fire", "speed density", And have a removable EPROM.

[DirtyLarry]

I forget about the TPI engines with port injection. Yeah, those were batch fired injectors running on speed density calculation. They ran alright at the time but don’t hold a stone up against todays LS engines. For the first year I ran my 8.1L on a Delphi MEFI4 ECM running batch fire on speed density. It made a huge difference moving to a mass air flow sequential injection system.

On the other hand, Direct Injection is new at GM….on gasoline engines anyway. The 3.6L first appeared in the 2008ish Cadillac CTS then several GM cars after received it including the new Camaro. My wife’s 2010 BMW 335xi has twin turbo DI straight 6 that runs like a scaled dog. Chrysler also has their version of a DI 3.6L engine that came on scene in 2010, which is getting great reviews in the Jeep Wrangler. I believe Toyota has a DI engine in the new 4Runner as well but I haven’t heard of any carbon problems with any DI gas engines. 2014 will begin of the Gen V small block V8 with DI. Should be pretty exciting! I have little faith in GM to ever design a decent truck after the horrible 2007-2013 GMT900 truck fiasco but we can rest assure the new 2014 trucks for will have sweet engines!