Hot Rod Forum banner
1 - 7 of 7 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
Before I start, let me say this.. I am good around a wrench. If I'm told what to do, I can pretty much figure out the small stuff along the way. But when it comes to planning, I am pretty much clueless when it comes to engines.

So here we go..

I have a 1995 Chevy C1500 with a 5.7 V8 350. It has what I beleieve is refered to as tbi, even though i've been told its not truely tbi.

Anyways, what I want to do it cast all this aside and convert the truck to a true vortec, with individual injectors and the whole 9 yards. The block should be the same, right? So beside the heads and the computer, what is needed to do this? I've heard the power is better and so is the MPG. I would appreciate this to be as broken down as possible... If you want to call me stupid, have at it... I pretty much am when it comes to engines... (but let's try to get past that :) )
 

·
Registered
Joined
·
2 Posts
Discussion Starter · #3 ·
along the same lines

I was thinking pretty much the same thing... try to find a smashed donor truck to take the parts from...

I guess my question boils down to this. Assuming I find a complete donor truck that has been in a wreck or whatever; what can stay and what must go as far as the my truck. My current engine is still under 100k running like a champ, so I really would like to keep as much as I can. I have the feeling like this is a stupid question for some reason..

Or should I just basicly move the entire top end of the motor, transmission, ecu, and wiring over to my truck and find my way as I go?

Any pointers?
 

·
WFO
Joined
·
5,030 Posts
It's possible to use Vortec heads on your engine, then mount a 4 barrel intake made for the Vortec heads onto them. Then you can use a TBI adaptor to reuse the TBI from the present engine.

If you can part w/the better part of $400, use the made-for-the-purpose GM INTAKE.

In either case, you will be reusing the entire original engine and drivetrain including the ECM. The possibility exists that a chip could be wanted in order to take full advantage of the heads- especially if a cam swap is being considered.
 

·
Hates: Liver. Loves: Diesel
Joined
·
6,307 Posts
my two cents...

put vortec heads on it, use a vortec carb intake, and put a 454 TBI on it. It will bolt right up to a spreadbore flange. The small block TBI flows 390 cfm. The big block flows much more.

Then I think all you really need to do is reprogram the computer to recognize the BBC TBI and whatever cam you use.

A good source for vortec carb intakes is Ebay. Lots of guys buy Vortec crate engines and then swap out the intake for something that they think is better. The GM spreadbore vortec intake is very nice and will do well up to 5000 rpm. I grabbed one as a brand new take-off for $75.
 

·
Registered
Joined
·
15,314 Posts
kickit2 said:
Before I start, let me say this.. I am good around a wrench. If I'm told what to do, I can pretty much figure out the small stuff along the way. But when it comes to planning, I am pretty much clueless when it comes to engines.

So here we go..

I have a 1995 Chevy C1500 with a 5.7 V8 350. It has what I beleieve is refered to as tbi, even though i've been told its not truely tbi.

Anyways, what I want to do it cast all this aside and convert the truck to a true vortec, with individual injectors and the whole 9 yards. The block should be the same, right? So beside the heads and the computer, what is needed to do this? I've heard the power is better and so is the MPG. I would appreciate this to be as broken down as possible... If you want to call me stupid, have at it... I pretty much am when it comes to engines... (but let's try to get past that :) )
Whew, this is a taller order than you realize, but lets back up first.

Your 95 is a true TBI, make no bones about it. You're far more likely to find a non-California 96 with a Vortec and TBI than a 95 anywhere with a complete Vortec in it; and TBI is TBI it doesn't come in variations other than barrel count or layout such as the ill-fated Corvette, Cross Ram TBI.

A "complete Vortec" is where there can be some strange combinations of incomplete Vortecs as 95 is a transition year leading to the 1996 Vortec and as the 1995 production year progressed you can find a combinations of some different elements to the OBD-1 TBI system:

1) Of course the true pre Vortec L05 most likely built on the 14093638, 350 block casting. It will have swirl port heads and TBI.

2) The 880 Vortec block with or without a roller cam, but provisioned for a roller of not so equipped. With earlier Swirl Port heads and TBI.

3) Again the 880 vortec block but with Vortec heads and TBI. While these are publicly listed against the 1996 G30 van, I've found these things in very late 95 production pick ups. The essential thing is that the TBI injection and the qualified emission system remains OBD-1.

For 1996 the systems on the truck become OBD-2 emissions compliant and along with the Vortec engine and its beyond weird injection set up share nothing much in common with your 95. To change to a true Vortec of 1996 and up will require the entire systems come with it. This will be a major change to your electrical system and has been suggested if you really want to go this route the best way is to find a donor wreck and get everything between and including the fuel tank to the exhaust tips.

The Vortec injection like I said is rather weird as how GM went about it having the timed electric injectors in the middle of the intake, each feeding a hose to a port injector that is nothing more than a pop off valve. So they built two failure points into the injection instead of one and it has its problems. Go figure?

As has been stated, it is possible to use Vortec heads on your existing block, with the TBI. But your engine still has the anemic LO5 cam but don't worry the L31 has the same anemic timing, it just in a roller cam, so the L31 does not take full advantage of the heads because there isn't enough cam to work them up to their limits.

As has been suggested, you can really wake the LO5 up the L31 heads, if you're rebuilding the bottom end I'd also recommend that you get some D shape dish pistons with the dish sized to arrive at not more than 9.5 to 1. This piston configuration greatly enhances swirl and increases low to mid throttle mixture density up against the spark plug making for a more reliable and faster burn. For a cam if this is a flat tappet only block the Edlebrock 3702 this moves the timing up quite a bit and theoretically doesn't require a new chip for the TBI. If you have a roller block the GM LT-1 cam is quite close to the Edlebrock and should also be compatible with the existing TBI chip. I reality the sum total of typical hot rod changes such as the switch to Vortec heads, the longer duration cam, headers and dual often take changes beyond what the block learn module can deal with and a new custom chip becomes necessary. TBI is very sensitive to manifold pressure (vacuum) Cams with lobe timing around 190 to 220 degrees is about as far as you can push these things with out at least a new chip, and further reduction in manifold pressure will dictate custom sensors that can seperate very small changes of manifold pressure against RPMs and throttle position into suitably large data input changes for the computer, stock sensors simply don't have this level of discrimination. These type changes take you to the really serious houses like TPiS, Howell and others.

You can also go to the larger bore TBI either by having your's bored out or getting a 454 unit or a Holley 507 all will flow into the 650 670 CFM range which will be more to the improved engine's needs.

Such an engine should deliver in the neighborhood of 300 hp without having to go thru the complexity of readapting your chassis' systems to the OBD II Vortec systems.

Bogie
 

·
Registered
Joined
·
762 Posts
Well, if you want real EFI with port injection, computer... why bother with the old design, go for a current model truck engine, 4.8, 5.3, 6.0litres. They are very good engines and will give you more power stock than your parts-mix! Very reliable, too. With engine mounts adapter and moving the trans crossmember, they pretty much bolt in. Then get your computer reprogrammed and your harness modified and your truck will fly like you did not think was possible!
The old style small was a very good engine, "was" being the key word here; the newer (Gen 3 and 4) small blocks are entirely new modern designs and are much better any way you look at it!
 
1 - 7 of 7 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top