I work at a Chevy dealership, and Ive always heard contradictory arguments about swapping in either a 350 TPI or carb. with my stock 305 TBI. TPI puts out more power ive heard (at least stock) and more reliable, but carb 350 is easier to install as far as electronics go and easier to tune (aint gotta mess with computers n crap, mainly mechanical). Basic noob question Im sure, but I havent gotten anyhelp from them. Figured Id ask some experts on here. I can get a 4 bolt 350 bare block for nuthin, so ima build form the ground up.

Ive been readin all that I can, and ive seen so many articles on TPIs and carb, but never really seen one that puts them side-by-side. Any suggestions/comments for the noob?

 

I think that is a little right, and a little wrong.

TPI did put out more power, stock, than any of the carbd counterparts. But there were no carbd 350s. Every time I have yanked TPI for a carb, the effect ws positive. IMO the carb will make more power. As far as reliability, a properly tuned carb is as reliable as any TPI setup. Just dont expect the holley you found in the back of your grandpas shop to fit the bill. After all, people drove cars every day of the year, long before fuel injection, and they were just fine.

 

Interesting logic.

People ate food long before the invention of the refrigerator, and they were just fine. People had light in their homes after dark before the discovery of electricity, and they were just fine. People pooped in an outhouse before the invention of indoor plumbing, and they were just fine.


As for me, I think I'll get a beer from the fridge and go poop not in the dark

Sillyness aside, you'll have more potential for hp (especially above 4500rpm) with the carb, but do expect it to require more attention than a fuel injected system. It will have to be kept in tune by you, with no computer to do it for you.

With a carb, you'll have what I've always thought of as a cold weather theft deterrent. Only you will know the secret code of how many accelerator pumps, and how much throttle it takes to start in 0 degree weather. For my car, it was 2 1/2 pumps, hold the throttle 1/4" open, and give the throttle a decent blip when the first cylinder fired. All that hassle being said, I still miss my carbed LG4. There was just something about the smell of a rich-running fully-choked car warming up in January that woke me up better than any cup of coffe ever did.

 

CARBURETOR = OUTHOUSE

I like that analogy!!

The real question always breaks down to specific application and what you're willing to live with. Myself, I want as much as possible of everything. Carbs always seem to stick it to me as soon as I go from a weekend at the strip to wanting decent mileage for a long trip away.

 

In general, there is nothing wrong with FI,
but,,, the TPI version of FI is poor.
The intake manifold is unnecessarily restrictive.
With TPI, you have few options.
With a carb, you can select from many intake manifolds,
or consider,other mpfi options.

 

On the contrary, with tpi, you only need a good manifold. Everything else is there. Just ask the guys who've replaced theirs with an LT1 or Holley Stealth Ram manifold. The results on this board speak for themselves. Much less everybody else out there who's done it.

 

In other words, since neither of those other things is TPI, the logic goes like this:

"With TPI, all you need, is something other than TPI. Take off the TPI and replace it with some other form of FI with some performance potential, and your car can have a chance to keep up with an otherwise similar carbed one".

 

Wrong!! tpi includes wiring, computer, throttle body, injectors, etc....
Just changing the manifolding is the same as changing your old cast iron carb intake for a good one and re- using the same carb. Provided that you had a good carb to start with. Provided that there IS a good carb out there. It really only costs a few hundred bucks to upgrade the manifold. Not much difference in price to upgrading a carb manifold.

 

Tuned Port Induction is just that. If you change to a manifold that is not "tuned port", it ceases to be TPI. Then it's a short runner/miniram/whatever you call it.

The carb equivalent would be replacing a crossram manifold with a single/dual plane or a highrise, and still calling it a crossram...

I think most of the short runner manifolds are pretty neat systems, but I agree with RB83L69... Technically, it's no longer TPI

 

"A rose by any other name smells just as sweet"

If you replace your spreadbore Quadrajet with a square bore Holley, are you still carbureted?

If you already have a fuel injection system called "TUNED PORT INJECTION" and you replace the lower intake and runners with an accell superram or the entire manifold with an LT1 style manifold, is it still multiport fuel injected? I hope so, because you'd be getting rid of the weak point in the system rather than trashing the whole setup due to a name change that doesn't sound as technologically advanced.........

 

Thank you for making my point. I'm not suggesting it "smells any less sweet". I'm simply stating that when you remove the "tuned ports" from a TPI system, technically it's TPI "by another name".
Yes, and if you replace your TPI intake with a miniram, you're still fuel injected.
Yes, it would still be MPFI. Nobody suggested "trashing the whole system". We simply stated that by removing the "weak point of the system" (TPI intake&runners), your TPI MPFI system becomes just an MPFI system. There's nothing wrong with that, but you should refer to it accurately. If you remove a supercharger from an engine, is it still supercharged?

You're driving this horribly off topic. If you want to continue this pointless debate, go start you're own thread. I'm done with it, and will no longer follow you're off topic posts.

Regarding the thread topic
You're stock TBI system could have all potential of a carbed engine, if you wanted to take the time to put it on your 350 and tune the chip. You would retain the driveability, emissions, and economy of a fuel injected system, as well. Since it sounds like you don't want to get into anything computer-related, and you think you can tune a carb just fine, the carbed engine is probably for you. TPI would require the same amount of work with electronics/computer as TBI, so that's probably out as well.

My first car was an 87 with a carb, and I currently have an 89 with TPI, and an 88 with TBI, so if you can ask me a question about more specific differences, I can give you a more detailed answer

 

The point I was trying to make was that carbs have been around a long time, and proven reliable. I do appreciate your humor though .

Yeah, ask those guys, they got rid of the crappy TPI.

 

TPI = Tuned Port Injection..... a system mfd by GM, with 22" total length runners. Designed with the runner length "tuned" in such a way as to cause the acoustic pressure wave created by one cylinder's intake valve closing event, to reinforce the fill of the next cyl in the firing order. Only effective over a narrow band of RPMs, as determined by the runner length. Works out to about 3600 RPM for max enhancement. Runners and intake base are very small diameter, creating a flow restriction (and correspondingly very very low HP); as well as destructive interference from the acoustic effect above about 1.5 times the tuned RPM (i.e., the system works against itself above 4500 RPM)

Stealth Ram = a converted dual 4-barrel intake that Holley used to sell to street rodders back in the early 80s, with a horiz-draft TB plenum stuck on top instead of 2 4-barrel plenums. NOT tuned in any manner way shape or form

LT1 = GM's short-runner intake system introduced in the early 90s. Capable of achieving good flow (and therefore HP) numbers. Totally different in every way from TPI. Also, NOT "tuned" in any way.

If you start with a TPI and take off those stupid long runners and the restrictive drinking-straw base, and put some other intake on it, it isn't TPI any more; even if it's multi-port fuel injection. Wiring, injectors, etc., I could ( and have) put into a converted single-plane 4-barrel intake. Definitely NOT TPI any more. That stuff doesn't make TPI.

"Few" hundred bucks..... I suggest you investigate just how "few" it takes to upgrade each of those systems. I think you'll find it isn't worth spending a dime to upgrade a TPI. It's better to just turf it, and put on a MiniRam or whatever. That way you'll have a shot at competing with the carb guys.

 

this question's got a little out of hand for what he wants to know. let's simplify it a little. imo, carburetors suck. i wish i would have put efi in my camaro like i did in my blazer. i had a hell of a time tuning that damn thing (absolutely no computer controlled junk anymore - i mean as far as wiring headaches and engine bay clutter goes)and i had very knowledgeable people helping me. imo, if you want a daily driver, go with fuel injection. if you want something else, go ahead and put a carb on it. carbs are definitely way easier too (at least to put on) if youre worried about your skill level, but you'll probably need help tuning the carb. btw, im not implying anything about your skill level. you said you have read many tech articles. tell us the fundamental ideas and facts you have learned/know about their differences (relating to your question) and maybe that'll give everyone a better base of where to start.

 

Carbs don't necessarily suck.
...............
You DO have to get a bunch of stuff correct.
Typical mistakes are, carb too big, jetted too rich.
Carbs don't like ERG.
.............
Most people don't know that,
some time back,
most cars were carbed.

 

Your 100% correct. You left out 1 very important word though, Un-Tuned. When I put my motor together I had never held a carb in my hand much less tuned one. I bought a book, asked questions here and talked to friends. Before the motor went down the car started on the coldest mornings the same way everyday. 1 pump, start car, keep foot on gas for about 1 min, drive away. All without a choke. I have friends that can't get there Camander 950's programed to do that.

 

the biggest problem with a carb on a car is lack of knowledge if you dont know how to properly tune one or how to shop for the correct size carb for your application then you have no business owning one because those are the people that always come on here and say that carbs suck or this brand carb is junk or fuel injection is better because i dont have to tune it ...

if you put a carb on an performance engine and then put tpi on the same exact performance engine the carburator will out perform tpi ...on top end and anything over about 4500 rpms for the most part

 

Really, I think the question here should have been: Which is better aftermarket MPFI system or aftermarket carb setup?

 

THEGENERAL: youre right about the biggest problem with carbs being lack of knowledge, but it wasnt the case in my situation. fi isnt better just because you dont have to tune it: its just better. i dont believe for one second that carbs are better. maybe im nieve but efi is way more consistent and much less of a headache. we've all been a great help to this guy. just what he wants to know. i guess hes not going to respond to this topic anyway so why bother trying to help? just out of curiousity, do you have any data that compares the same engine under the same conditions having a tuned carb setup versus a tip setup? so youre conclustion is that he should get tpi since he knows nothing about carbs?

 

I don't have anything on paper but I'm sure I could get something. I have a friend that works at Holley. He installs their parts and dyno's set-ups. He also compares Holley stuff to Edelbrock and others.

IMHO, there is no need in seeing it on paper. Take a Comp 282HR (2200-5800rpm) and install it in a motor with tpi. The car will fall on it's face at 4500-4700rpm. Now install and tune a properly sized carb. It will pull easily to listed 5800 rpm taking full advantage of the cam. Now we know the 2200-5800 range isn't exact but I have no doubt that the tpi will stop flowing well before the cam will.

 

The biggest problem with carbs, is that you have to be more careful about what parts you use, because for it to work properly, all the parts have to "match". I mean, if you have a basic, low compression smogger 305, you can actually make it worse by dropping on a huge intake and a monster carb.

Thats because carb'd engines rely on 'mechnical signals' like engine vacuum to work properly. For a carb to work properly, the engine has to be able to provide a strong 'signal' to the carb. The stronger this 'signal', the better the carb will work. Thats why small carbs work better, and are much more responsive to tuning changes than huge ones on street engines.

The advantage to fuel injection, is that this doesn't apply as much, because it relies on the computer to provide the signals to tell it what to do next. It relies on info from the O2 sensor, knock sensor, MAF, etc... to tell it whats going on and what it should be doing instead of relying on mechanical signals like engine vacuum.

This is a huge advantage for fuel injection, because it makes parts that would be very radical on a carb'd engine, like a monster cam, massive throttle body, or a huge intake manifold, much more streetable and tame. These parts on a carb'd engine are what kill the 'signal' to the carb, and make it a much less tame and more radical engine, because the carb can't work as well with the diminished signal. This, in theory, makes fuel injection superior to carbs because you can make more power, and make it more reliably and with more practicality.

Carb'd engines take more planning to execute well, but when they are built and set up properly, they can make rediculous amounts of power, simply because of the huge breathing capacity thats available.

Carb'd engines are also so much cheaper to make HP with that its just not even funny. Compared to carb'd engines, EFI is noticeably more expensive to modify.

I have a carb'd engine in my Camaro, and I have a love/hate relationship with it. My 350, which has a Holley 4bbl on it, starts easier in the morning than my mom's '00 Sebering does. And this is in a Canadian winter. Hows that for reliability?

 

How about adding mileage into your reliability/ driveability equation? How much money are you really saving by running a carb setup that's properly tuned and efficient versus efi? I'm not a super carb tuner. I can't ever get any of my carb engines to come close to mileage numbers of efi and make the same power.

 

Yes you are. For a performance engine, IMO carbs are better. MAny people agree with this. Of course, it is an argument that will go on for ever.

Want some proof about performance? Go to a race track and start looking under hoods. Count the carbs on the faster cars.

As for reliabilty and ease of use, never had a problem out of a carb, but I know how to tune one. Learn how, and you will understand why us "old timer, out-house living, stone-age guys" swear by them. When its all said and done, we still have enough money left over for a cheeseburger too!

 

now were also dinosaurs remember...LMAO

oh and we can also get fries and an apple pie with that .....

 

If the engine is built with the right parts for its intended use, a carb can get you very good mileage, close to that of EFI, but probably not quite as high, simply because EFI can run on the ragged edge all the time, a carb setup usually cannot. By that, I mean that an EFI setup like TPI or an LT1 can run extremely lean during cruise conditions, much more so than a carb usually can, the ignition timing can be set to exactly what the engine wants for current running conditions (ie. idle, cruise, WOT) etc etc...

basically, EFI will get slightly better mileage on two otherwise identical engines simply because its a more presice metering system than a carb setup is.

But all the power, mileage, and driveability are still all in how you tune the setup you have. There are 150hp fuel injected 305s out there getting 10mpg, and there are carb'd 350s making 300+hp and getting 20+mpg.

Its all in the tuning.

 

*********

 

.
Keep in mind that, the driveability and economy of carbs,
was reduced by EGR. Once, slightly lean at cruise was OK,
with EGR, slightly lean causes driveabilty problems.
That limitated afr's, for carbs going in EGR cars, is not helpful.
The driveabilty problem is aggrevated by the
'enthusiasts tendency' to think that 'rich rich rich
big big big' is best for carbs.
When EGR is removed, a certain amount of 'design limitation'
is removed, and design parameters can be adjusted
to advantage.

 

I have a 1986 trans am that originall came with a 305 carb engine
when the engine laid down on me , I removed all emissions and engine , I installed a 1969 350 chevy with a carb and kept the install simple . the carb on my car is a holley 750 cfm, I tuned it my self and it always starts on first try.

but now it's time I think I should have went a little different route, I'm considering getting the holley stealth ram system and install other more modern equipment on my car.

I still love my carbs, but a carb's havent been used on new cars in years now. FI is becoming more of a standard now a days and if you think of the pros and cons of Fuel injection v carbs . carbs are being fazed out by fuelinjection, no matter if you like it or not, fuel injection in some form is here to stay.


in my opinion go with the fuel injection. but stay away from the early stuff, try to go with something more current, you will find much more upgrades for the new stuff.

 

I love carbs,and can tune one to the gnats ***,that being said,as soon as I get the rest of the pieces for my MPFI setup,I've got a 750HP Holley that will be for sale.