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Discussion Starter #1
want to swap my 350 to fuel injection and was wondering if a vortec setup was worth it over a tbi. tbi should be cheaper and less complicated. this is for a mild 350. either way i'd like to get vortec heads and a better cam at the same time. wouldn't mind a little room to grow in the future also. thanks alot
mark
 

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srv8800; said:
want to swap my 350 to fuel injection and was wondering if a vortec setup was worth it over a tbi. tbi should be cheaper and less complicated. this is for a mild 350. either way i'd like to get vortec heads and a better cam at the same time. wouldn't mind a little room to grow in the future also. thanks alot
mark
go ahead.

tell us how it works out.
 

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for simplicity and performance I'd go TPI. There are vortec upgrades of the poppet injectors which eliminate clogging issues but TPI is just plain simpler.
 

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I'm going to use a 454 TBI unit I got from a certain grumpy old fart. I did A LOT of research on this. I'll try and summarize for you...

1. The Vortec CSFI system is complicated and expensive
2. The stock Vortec system is barely adequate for a stock engine
3. There is not much room to grow the stock Vortec system
4. No one seems to know what the flowrate of the MPFI retrofit injectors is
5. The marine manifold conversion is expensive and looks somewhat involved
6. By the time you get the fuel rates up on a Vortec the stock intake plenum runs out of capacity for air because of its relatively low volume


TBI is not a perfect solution, but you can get a decent aftermarket intake with a quadrajet base and use either a cheap adapter plate, or better yet, the factory 454 adapter plate. Heck, you could even shell out the big bucks on the GM Performance Parts TBI Vortec intake. Maybe you could get really lucky and score the Vortec TBI intake off a van. No matter what you do you will most likely do it for less than trying to make the stock system work in any respect beyond stock.
 

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Tell me more about this van intake, why, I've never heard of such a beast! But I do enjoy the junkyard scrounging.

I absolutely LOVE TBI. For my long-range, mixed-use purposes, the reliability and part-store/junkyard availability of parts can't be beat. I almost talked myself back into the 350 because there's more of them, but the fat valve covers make me horny, so it's 454 or nothing now. ;)

I seriously doubt I'll run out of power with the very mild upgrades I have in mind, with the TBI setup. Everything else adds complexity where it is not needed, which is: in the engine compartment of a truck that will often be very far from diagnostic help. TBI works.
 

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Tell me more about this van intake, why, I've never heard of such a beast! But I do enjoy the junkyard scrounging.
Legend has it that in 1996 a great beast existed. It took the form of the Chevy G3500 van with an 8500 lbs GVWR and a 4L80E. This mythical creature is rumored to have derive its power from an L31 Vortec 350...but this was no ordinary 350...this 350 fed its insatiable appetite for fuel and air through a throttle body injection set up meaning that there was, in some way, a factory TBI-Vortec intake setup, be it a quadrajet pattern with an adapter of some type or a true 3 bolt TBI set up.

I have never been able to substantiate the existence of this arrangement. I cannot even find listings for it in the parts catalogs. But I truly believe it is out there somewhere. Afterall, Fel-Pro doesn't list a master gasket set for the CSFI Vortec engines and they exist. Google searches have led me only to pictures of third gen Camaros with Vortec heads swapped onto factory TBI motors.

I have enlisted a crack team of believers to help me in my quest...

 

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This mythical creature is rumored to have derive its power from an L31 Vortec 350...
I thought all the L31's were Vortec (CPI) fuel injected starting in 1996. I don't think there were any factory TB injected L31's (L31 factory code for 350ci Vortec headed/CPI motors)....?? Hmm?

Ahhh, I stand corrected, read down to the 5700 (5.7)
section.

http://en.wikipedia.org/wiki/Vortec

They do mention (as stated) an L31 TBI......Hmm, the mythical beast must have existed...and may still live on to this day.....some where.
 

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Ah man I think there was one of those in a junkyard here couple months ago!!! Went looking around at stupid shit, peaked inside a van, looked at the motor, thought about taking the heads, (it was a 96) but then after a closer look it had TBI on it. I don't remember if I looked at the head/intake bolts or not.....

I've had alot of TBIs, bunch of small blocks and 1 big block, and 1 Vortec 454. All of the TBIs I had were OK save for my 92 Blazer, thing is a DOG. Had a killer TBI406 in my old truck, and the 454TBI was a monster as well. I had a 97 and it was different to drive, needed more "pedal" to go, whereas the same pedal in a TBI would put you back in the seat.

I'm staying with TBI. It's simple, cheap, easy to get parts for, and can build them up more than a Vortec I think. Gonna be building 2 400s, at least 1 with Vortecs.

Inless your building a stock motor, don't run the GM TBI/Vortec intake, they don't flow very well.

Anymore info on this TBI/Vortec intake??
 

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b454rat,
Can you tell me more about your 406 TBI? I was thinking about doing a low rpm tow motor.....swapping out my 350TBI in my 1994 K Blazer....essentially putting a 406 under the mostly stock stuff......possibly using mild upgrades such as one would do for a 350....but with a 406 short block......again, low rpm TQ is my goal....3500 rpm and below.
 

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I used ALL the stock stuff off a 90 GMC. Basically just swapped it out for a 406. Used the stock style TBI heads, just plane rebuilds. I used the stock crank, but used 350 5.7" rods, KB pistons, IIRC was 9.8:1 comp. Comp Cams Xtrme Energy 268 cam, headers, 3" y-pipe into a Flow w/ dual 2 1/2" pipes out the back.

The truck ran awesome. Would idle all day long, (sweet idle at that!) would smolder the tires at a standstill, but the tranny was getting bad, so didn't do that too much. With that motor, 700r tranny, killer 3.08 gears and 28" tall tires, got around 20 mpg. It had torque all over, down low, midrange, high, would pull in any gear and would not downshift on hills. There are some steap ones on I-81 north in PA.

I just picked up a 406 block, just need to get it tanked and bearing installed. Found a crank, just need to get it and start putting it togther. One of these 400s that I have is going in a 2wd S-10 Blazer, that's gonna be fun....
 

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Discussion Starter #12
sounds like i'm putting tbi ontop of vortec heads with an edelbrock intake manifold and an adapter plate. anybody see any probles with this setup? headers? dist? sugest an inline fuel pump? anything i should have a machine shop do to the heads before install? thanks alot
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Ive got a 93 and a 95 TBI , simple , parts are cheap if it ever breaks. My 93 still has the origional 2 injectors in it 230K miles. You can get a prom programmer from craig moates for $85.00 and 50 for a chip adapter , $5 for blank flash reprogrammable chips. $30 for tunerpro software and you can edit your fuel, timing, convertor lockup, and shiftpoints and a bunch of other crap on the electronic trans trucks.
 

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I used ALL the stock stuff off a 90 GMC. Basically just swapped it out for a 406. Used the stock style TBI heads, just plane rebuilds. I used the stock crank, but used 350 5.7" rods, KB pistons, IIRC was 9.8:1 comp. Comp Cams Xtrme Energy 268 cam, headers, 3" y-pipe into a Flow w/ dual 2 1/2" pipes out the back.

The truck ran awesome. Would idle all day long, (sweet idle at that!) would smolder the tires at a standstill, but the tranny was getting bad, so didn't do that too much. With that motor, 700r tranny, killer 3.08 gears and 28" tall tires, got around 20 mpg. It had torque all over, down low, midrange, high, would pull in any gear and would not downshift on hills. There are some steap ones on I-81 north in PA.....
Interesting, exactly what I had in mind. I was kind of hoping the mileage would improve some due to the of extra TQ 406 can make. I've got 3.73's with stock size LT265/75/16.....it'll probably be more gear that the 400 would need. Sounds sweet....Thanks!
 

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like this one
That would appear to be the GMPP intake to me, but is it possible that that is the mythical creature?


I think going TBI was the right decision. There are other systems out there that might offer better throttle response or more power, but you can't beat the all out simplicity of the TBI or the parts availability. I mean lets face it...you can damn near buy sensors for a Chevy TBI at 7-Eleven and can get most for a single picture of Mr. Jackson. The ironic thing is...you probably won't need to get many replacement parts.
 

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Legend has it that in 1996 a great beast existed. It took the form of the Chevy G3500 van with an 8500 lbs GVWR and a 4L80E. This mythical creature is rumored to have derive its power from an L31 Vortec 350...but this was no ordinary 350...this 350 fed its insatiable appetite for fuel and air through a throttle body injection set up meaning that there was, in some way, a factory TBI-Vortec intake setup, be it a quadrajet pattern with an adapter of some type or a true 3 bolt TBI set up.

I have never been able to substantiate the existence of this arrangement. I cannot even find listings for it in the parts catalogs. But I truly believe it is out there somewhere. Afterall, Fel-Pro doesn't list a master gasket set for the CSFI Vortec engines and they exist. Google searches have led me only to pictures of third gen Camaros with Vortec heads swapped onto factory TBI motors.

I have enlisted a crack team of believers to help me in my quest...

Your crack team should have called GM. They did indeed do a 96 G3500 with a 4l80E and 5.7. It had head # 12516852 on it which was used from 87-95. Vortec heads were used 96 and later. So this "beast" was simply a standard TBI with a 3500 drivetrain. Common practice for GM. From 2000-2002 they were still using the 5.7's in the Express vans even though the pick-ups had the 5.3's and 6.0's.
 

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I'm going to use a 454 TBI unit I got from a certain grumpy old fart. I did A LOT of research on this. I'll try and summarize for you...

1. The Vortec CSFI system is complicated and expensive
2. The stock Vortec system is barely adequate for a stock engine
3. There is not much room to grow the stock Vortec system
4. No one seems to know what the flowrate of the MPFI retrofit injectors is
5. The marine manifold conversion is expensive and looks somewhat involved
6. By the time you get the fuel rates up on a Vortec the stock intake plenum runs out of capacity for air because of its relatively low volume
.
1. CSFI isn't that complicated but you will have to do some reading. Tuned port (TPI) and TBI are much simpler. You'll get better fuel usage out of CSFI though.
2. The stock vortec system according to Chevy can run a 340 HP and 435 ft. lbs. They list the HT383E as a drop in replacement for the 5.7 CSFI's.
3. True when you're getting into big HP applications you do need to make some changes like an intake/injector swap such as the Marine Manifold you mention in line 5 which will run you 80 bucks for the computer and 500-700 for the intake plus your labor to install. You'll also need to buy a tune for 150 or so.
4. 19lbs.
5. - see 3
6. The only way to get the fuel rates up on the stock plenium would be to increase fuel pressure since there are only the poppets and the 19 lb. replacement mini injectors - both of which will push a torquey 383. That same 383 you can run to the 5250 RPM cut-off so I'm not sure why you'd worry about running out of air.
 
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