TBI, TPI, and Vortec- which to go with?

Once the Challenge is over, I'm planning on converting the 350 in the El Camino back to EFI of some sort. I have the TBI setup already since it's what the engine started off with (though I'd be going with a MegaSquirt setup to control it). I'm going to be using Vortec heads, so simply getting the Vortec intake and injector setup seems like it would make sense. And there's also the option of getting a TPI setup and the intake necessary to mate it to my Vortec heads. All would be run by some form of MS.

What are the ups and downs of each? I'm hoping to get a bit more efficiency out of the engine but would still like it to perform well too...

you don't want to try to run the screwball vortec injection setup.. and if you want more than about 300hp you don't want the TBI setup. just keep it a carb and be happy with it. a well tuned quadrajet will do everything well and support upwards of 500hp if you get an 850cfm setup.

novaderrik wrote: you don't want to try to run the screwball vortec injection setup.. and if you want more than about 300hp you don't want the TBI setup. just keep it a carb and be happy with it. a well tuned quadrajet will do everything well and support upwards of 500hp if you get an 850cfm setup.

This

The easiest plug n play aftermarket EFI by far is MSD's atomic EFI. It's not cheap, but very very simple.

BTW, that cylinder head shop that you went to, was it the one on Forbes st?

BoostedBrandon wrote: BTW, that cylinder head shop that you went to, was it the one on Forbes st?

I'd only go to Roberts or Backs. Backs did all the Chrysler heads I had to get fixed over the years while in Lex....

In reply to Ranger50:

I'm using Backs. They were the shop most highly regarded & recommended by the rotary shop, and I've been happy with what I've seen from the so far. I just wish I were home to be able to get the four new heads tested.

So, the Vortec is apparently a real pain to work with. How about TPI?

Ashyukun wrote: So, the Vortec is apparently a real pain to work with. How about TPI?

Are you talking the TBI Vortec or the mini-ram LT1 Vortec?

Only problem I ever saw with TPI was the runners were a HUGE choke point in being able to make any power. Plus there was a huge boss that restricted flow right behind the TB entry. If you want to find some, there are still AM runners that fix most of the choke point and a grinder fixes the boss.

mod LT1 intake to bolt to the vortec heads, machine for distributor(they sell plate that bolts to intake for distributor mounting and you drill the hole), and build your own EFI off that?

i had an LT1 intake modded to fit a traditional SBC head pattern and it worked fine. the vortec it seems should be easier because you don't need to mess with center intake bolts, and those are the hardest part of the whole deal.

it all really depends on what power you wish to make, what rpm range you wish to operate in, how big a cam, etc...

I don't venture past Versailles Rd, that's where I work and I turn around and go home, I just happened to roll down Forbes a few weeks ago and spotted that place, wanted to check and see if that was it since it's very close to work.

patgizz wrote: mod LT1 intake to bolt to the vortec heads, machine for distributor(they sell plate that bolts to intake for distributor mounting and you drill the hole), and build your own EFI off that? i had an LT1 intake modded to fit a traditional SBC head pattern and it worked fine. the vortec it seems should be easier because you don't need to mess with center intake bolts, and those are the hardest part of the whole deal. it all really depends on what power you wish to make, what rpm range you wish to operate in, how big a cam, etc...

go that route, then you have to figure out how to get the coolant out of the engine and where to put the thermostat since the LT1 intakes don't have a water crossover.

also, the vortec ports are taller than the LT1 ports- but smaller than the LT4 ports- so you will never get a perfect match. you can buy a TPI lower intake for the vortec heads, but that's a bunch of cubic dollars to spend, and then you need to spend more $$$ on aftermarket runners so you don't choke it off.

honestly, a carb is the best bet. a well tuned quadrajet will get similar mileage to a TPI setup and run just as good, with the only real seasonal tweaking being maybe adjusting the opening of the choke and turning the idle mixture screws out a quarter of a turn if it gets really cold.

honestly my vette runs better than TPI and gets the same mileage with a properly tuned holley. but hey, the guy wants EFI - let him have some options.

really the best way probably would be buy a 4bbl vortec intake, drill some holes in the runners and mount injector bungs, make your own rails, and adapt a throttle body. they probably have an intake that already has the bosses to machine for injectors even.

Fine! I'll be the one to say it.

Ellis Juan.

There, it gets mentioned in nearly every damn thread.

patgizz wrote: mod LT1 intake to bolt to the vortec heads, machine for distributor(they sell plate that bolts to intake for distributor mounting and you drill the hole), and build your own EFI off that? i had an LT1 intake modded to fit a traditional SBC head pattern and it worked fine. the vortec it seems should be easier because you don't need to mess with center intake bolts, and those are the hardest part of the whole deal. it all really depends on what power you wish to make, what rpm range you wish to operate in, how big a cam, etc...

Where does one find these LT1 intake conversion parts? I've got an intake that could find some use if it was converted.

http://www.eecis.udel.edu/~davis/z28/lt1intake_conversion/

the site where stuff was available is down.

i dunno, i had one and it was nicely done. yeah there are better options out there, but if you can be cheap and DIY it, no harm there.

As much as I enjoy aftermarket EFI, a Q-jet on a mild engine is a VERY difficult combination to beat for drivability and economy.

Qjet is awesome. I would rather have a Qjet than a TBI any day. The vortec intake is a bit awkward with the spider injectors can be problematic, but not any more than the TBI.

the LT1 intake conversion a not really a wise choice. You'll spend a fair amount of time converting bolt holes and you'll just have ports that don't line up very well.

My first choice would be a Marine Vortec intake. They have traditional external injectors that are easy to service if they fail.

curtis73 wrote: Qjet is awesome. I would rather have a Qjet than a TBI any day. The vortec intake is a bit awkward with the spider injectors can be problematic, but not any more than the TBI. the LT1 intake conversion a not really a wise choice. You'll spend a fair amount of time converting bolt holes and you'll just have ports that don't line up very well. My first choice would be a Marine Vortec intake. They have traditional external injectors that are easy to service if they fail.

you mean the one used on the ramjet 350 crate motor? the one that doesn't clear under the hood of any car built after 1967 or so?

If you do go with TBI or TPI i would suggest checking out this alternative to megasquirt for tuning. http://www.dynamicefi.com/ It is Really plug and play, you can install it yourself or, just remove your ecu and send it to them, get one back with a usb port to plug right in and begin tuning. My buddy swapped a 350 With vortec heads and TBI into his camaro (was a TBI 305), and used dynamicefi to tune it, it gets 20+ MPG on the freeway and runs low to mid 14's in the 1/4mile. itll definitley be my next modification to my Trans AM

novaderrik wrote: you mean the one used on the ramjet 350 crate motor? the one that doesn't clear under the hood of any car built after 1967 or so?

I... Have to admit, I think that looks rather awesome even if it might have a hood clearance issue...

Doing some searching, it looks like the bare intake isn't much more than the Vortec TPI intakes are. The throttle body doesn't look like it's the same as the TPI units, but is the fuel system compatible? Summit carries the full intake kit with injectors and everything for a pretty penny... probably more than I'd want to pay, but it would deinitely be nice...

Some thoughts about the different intake setups being discussed.

TPI - had this on an '86 Corvette. Great low end torque but ran out of breath at 5,000 RPM. Might be a pretty good intake for my C10; it depends on your goals.

TBI - We tried a TBI setup on the DIYAutoTune.com Nova. Performance was OK on an engine making 200 wheel horsepower but was hampered by fuel distribution issues. The 350 TBI looked like it would be a restriction on a more powerful engine. I've thought about trying two TBIs on a dual quad intake on my truck just because I could probably build it cheap and we get a few customers asking about such a thing.

No personal experience with the LT1 intake, but it looks like more performance potential for more work.

MadScientistMatt wrote: Some thoughts about the different intake setups being discussed. TPI - had this on an '86 Corvette. Great low end torque but ran out of breath at 5,000 RPM. Might be a pretty good intake for my C10; it depends on your goals.

Good to know since the TPI is what I'm most realistically looking at (I'd love the Ramjet, but that would be lilke 5x the cost unless I find someone selling one used...).

I would guess that better aftermarket intake runners and higher-flow lower intake (I'd need an aftermarket one to run Vortec heads anyway...) would probably help with 5k RPM issue?

Yeah, that was a totally stock TPI motor. There's parts to improve the TPI out there.

Yes, TPI is great for low end, the LT1 type intake for horsepower a little further up the range. Vortec intake / injection is fine in a stock application, but I wouldn't use it for a 'custom' build.

I like the idea of "dual quad" TBI's, thought of using 3 small 2.8 V6 units for "tri-power"

In reply to midniteson:

The dynamic EFI system looks interesting, but my only concern with it is that it looks like its not really set up to be able to handle forced induction, and I'm toying with the idea of going to a twin turbo setup down the line (part of why I want EFI over a carb...) whereas MS handles that just fine...