Now I know there has been a lot of questions about tpi-tbi-and carb. People in the carb section diss the TPI and fuel injection and people in the TPI section my carb seem worse. But there really hasnt been any factual information to show which one is better more so just opinions. From what I have ready TPI gives ya 60 hp more over a carb. And from my knowledge you can bet more power out of fuel injection then you can get with a carb let alone better mileage, but who cares about mileage. Ive heard many times that the gm tpi unit it to restrictive to get any major power out of it and hi rpms and therefor a carb is better. But lets say you buy new runners and do some porting can you then get more flow than a carb. I would like to get some opinions on this but would like to see some facts to. For me the TPI looks a lot better than a carb does in a 3rd gen f-body anyways, looks pretty bad ***. I big reason I am asking this is because in the future i plan on getting a gmpp 350HO and putting a Holley StealthRam MPFI system on it instead of a carb, yes it is much more expensive but if i can get more power out of FI over carb it would be worth it. Plus I just cant bring my self to putting a carb in my 3rd gen, I love the looks of the TPI and dont think I could change. Sorry its so long but if anyone can clear this up for more and probably many other people I would appreciate it.
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1989 Trans am 305 TPI Automatic, 2.73 rear, K&N filter, underdrive pulleys, air foil, tb bypass, low restriction exhaust

 

my opinon:

aftermarket tpi > carb

stock tpi = good for general street use, but cant rev very high in n/a form

carb can give you a better powerband, both can be made to run pretty good tho, stock tpi usually doesnt beat out a carb tho, thats where stealth/super/mini ram come in to play tho eh

 

350HO's have Vortec heads on them and the HSR wont fit on there.

 

So your saying as long as you do a little work to a TPI it is better than a carb. I might be able to switch to carb if I knew it was a lot better but as long as I can get more power out of FI im sticking with that no matter the cost.

 

Nothing wrong with a carb in a third gen!

 

When both are properly tuned the difference in peak power potential between a carb and EFI is nonexistant.

Carbs are a lot cheaper than EFI.

EFI makes more torque throughout the RPM band, especially at low RPM. EFI is also a lot easier to live with on a daily driver that must start on cold winter mornings.

The factory TPI system is, like all parts used in production cars, a compromise. It offers great low end torque, but not much up top. This is what most people want on the street. To really get a TPI to perform up top you need new heads, cam, and intake system, as well as a full exhaust.

There is no good or bad, it all just depends on what you have and what you want your car to do. Carbs are the old performance staple, and they are going to be around for quite some time, even though one hasn't been installed on a new car in a very long time. A lot of old guys don't know anything about EFI, so they don't like it. Well, the fact is that EFI is the wave of the future. Most new school car guys don't know much about needle and seat assemblies, but a fuel and spark map are second nature to them. There's nothing wrong with EFI, but if you plan to modify it you need to do some reading, so that you're up on the terms and how it works.

I know you want a black & white answer, but it really all boils down to opinion.

 

TPI is better.
haha

 

I have had both. My 86 Z28 was a carb motor w/o A/C and emissions. Easy to work on, you don't have to worry about tuning a computer if you do mods (cam, heads, bigger carb.)etc.

TPI gets better gas milage, more torque around town than a carb, better throttle response. Harder to work on. You have to get chips burnt after doing serious mods like cam, heads, injectors etc.

I like both. I love my torque but I also like to spin over 4500rpm too.

I guess it comes down to who will be working on your car more.....you or a mechanic. Also if the car will be a daily driver or not.

Hope this helps a little.

 

i love my tpi over my 305 4bbl alot better on gas mileage....no flooding the engine when you step on it, alot better response its instant....

 

well, I am about to do a major conversion to my car converting from carb to TPI, so I will let ya know from personal reference, but this is what I know from past experiences and just common knowledge:


FI in general is more reliable, gets better mileage, easier to maintain, overall just more "streetable. Carbs are cheaper, much more simplier (line in for gas, air filter, and trottle cable, thats about it ), more common for parts and such, and more common among mechanics and such.

like it was said before, it just depends on the driver. I really need to get good fuel mileage, plus my carb on the car right now (is stock GM, and on a '86 Caprice Classic) is giving up, and it is idling rough, plus hesitates more that I like when I punch it. FI will fix all my problems, give me more power (I am putting in a 350 anyway, but....), better fuel mileage, and make it look better IMHO.

now, the TPI's main weakness is that the powerband in kind of short (in OEM style), but this provides GREAT power until that powerband dropoff. Just a decision between driver and motor.

 

Today, I'm leaning towards carb being better.
I'm in the middle of a fixer upper TPI project that I picked up a year ago. And I sorely wish that I lived in a state that allowed carb swaps cause if I did, I'd be driving it now.
Carbs are vastly simpler to work on, especially troubleshoot, IMO.

 

I have an HSR set-up. The TPI is too restrictive. Nothing over 4500rpms. Thats how it was designed. If you have a 305 or 350 some porting will help but again nothing over 4500rpms. Anything over a 350 will not help no matter how much proting you do. I tried it. There was only a small difference even with porting from the intake on up. TPI is mainly for low end torque. Barry Grant sells at least one carb that claims to have almost the exact same response on the throttle as FI. I dont remember which one it is. For a daily driver FI is better but more difficult to tune. For racing, a carb is better unless you have a supercharger on your FI set-up. Its all a matter of preference really. If you want numbers, there are plenty available. Do some searches here and on yahoo etc...

 

I lean toward TPI. But stock for stock both cars will have a birdsnest of crap under the hood.

 

Exactly what I would say... Except I "have" not "had"

 

is'nt it tough to pass emissions with a carb?...almost impossible?

 

Actually I think it's easier to sneak by the sniffer with a carb. You can actually fiddle with the dile mixture, unlike with EFI, where you would have to burn a new PROM. I know a lot of guys that sneak pretty radical combinations past the smog ***** just by leanign out the idle mixture a bit and advancing the timing at idle. The car runs like crap, but it sneaks past. Then they just pull into a parking lot on their way home and return the settings to normal.

Properly tuned EFI should be superior in terms of getting the car to pass, but the key are those first two words.