Vortec V8 vs. LT-1/LS-1

OUMike · April 23, 2003

Hey everyone,

Just wanna take a minute to introduce myself as a new member of the board. My name is Mychael Houck, and I'm the proud owner of a 94' Silverado 4.3L. I joined the board to learn more of my truck, and I've found these are great for troubleshooting any problems that I come across.

I've recently begun shopping for a 1998 5.7L SWB, and I was curious as to what kind of aftermakret crossovers between the Vortec V8, and say an LT-1/LS-1. I was thinking along the lines of maybe intake manifold and/or heads. I have been told that the heads that come on the Vortec are pretty free flowing, and a good for performance. If anyone has any ideas on how to squeeze more power from the Vortec w/o using NOS or expensive Superchargers I'd be open for opinions. My goal HP is about 300-330. I figure thats what I'll need to play with Mustang GTs. My 94' weighs about 4600lbs I believe, what do the 98s weigh?

CMNTMXR81 · April 23, 2003

OK, first things first. All truck engines (V6 and V8) in Chevy trucks have been dubbed "Vortec" since 1996. At that point ('96), the choices were the Vortec 4300 (4.3L V6), the Vortec 5000 (5.0L V8), the Vortec 5700 (5.7L V8), and the Vortec 7400 (7.4L V8). The Vortec 5000 & 5700 are the old school small block Chevy design who's architecture traces back to the 50's. The differences between the LT1 engine and the old school SBC is that the LT1 utilizes reverse flow cooling and an Opti-Spark (dubbed "Opti-Crap") optical ignition system. The Vortec engines used standard flow cooling system and a conventional ignition system. The Vortec 5700 heads are a cheap upgrade for the old school SBC and generally flow, tumble and swirl right up there with more costly sets of heads. However, it you opt to go with the Vortec head, you'll have to get a different intake as the bolts are different. Edelbrock I know makes an intake manifold that works with the Vortec heads.

Now, enter the LS1. The LS1 is a completely new from the ground up all aluminum engine. The only thing it has in common with the previous generation SBC mentioned above is the number of cylinders and the bore centerlines. Otherwise, it utilizes 6 bolt mains for each main (not just the ends), deep skirt block, Nodular crank, hollow cam (commonly replaced with a solid steel billet unit), awesome flowing replicated oval port heads, positive decked block, and a whole list of some pretty trick engineering.

The New line of Vortec truck engines, the Vortec 4800, 5300, and 6000 are simply cast iron versions of the all aluminum LS1 above.

To sum it up, Old school SBC LT1 parts ARE NOT interchangable with the LS1 and as such, the Vortec 5000 & 5700 parts ARE NOT interchangable with the LS1 derived Vortec 4800, 5300, & 6000.

Does that help?

Tucson_02Silverado · April 23, 2003

You have inquired about three different generations of the Small Block Chevy (SBC)

The 96-99+(classic) Vortec is part of the Generation I (Gen I) SBC which runs from 262-400CI since 1955 with minor variation in base block in 1985, basically switch from two piece to one piece rear main seal. The 400 block was also a variation being siamesed cylinder walls. Of course there are other small variations throughout the entire generation, but those would be the two of big ones. Common is parts for a 283 will work with a 400, how well is another matter.

The LT1/LT4 is Gen II 350CI only displacement

The LS1/LS6/Truck (4.8,5.3,6.0) are Gen III

There is not much parts that will interchange between the Gen's. A couple between Gen I and II. None (that I'm aware of) between I and II to III

OUMike · April 23, 2003

Hmm...

So that means that because the current performance motor for GM in 98' was the LS-1, and the LS-1 and Vortec share NOTHING in common...there is pretty much no way to interchange internals. Does anyone (LPE, Callaway, Jeal ect.) make any parts for the Vortec 5700 for horsepower gain?

As far as the generation differences between bodies, I know my current 94' uses a TBI injection system. would it be a correct asumption that all 94' motors (4300, 5000, 5700) used Throttle Bodies? If so, when did this start, and when did EFI start? I've seen some older (92ish) Silverados with EFI badges on the tailgate. Is there a website I can go to, or a book I can buy that will break down the Silverado drivetrains by Generation?

Charlie in TX · April 23, 2003

OU, EFI stands for Electronic Fuel Injection. TBI (thottle body injection) is one type, MPI (multi-point injection) is another. The change from TBI to MPI was in '96.

As far as modifications to the '99 classic and older trucks, well, the 350 is probably the most modified engine ever. There should be plenty of mods available.

On Edit:

To play with stangs you will need to open up the intake (K&N intake kit) and exhaust (cat back) and a power programmer (hypertek). I think that should get you into the upper 200s. If you really want to 'play' the supper charger is the way to go.

OUMike · April 23, 2003

Hey Charlie,

Yea I understand the fuel injection thing and all, but I wasn't sure when the EFI started, and when the TBI ended. How much you think I could find say a Paxton, or Whipple Supercharger for that application? Tha'd probably give me about what?? 300-315 hp?

Do you know of anywhere that I can go, to learn about the late model C/Ks? ??? ???

OUMike · April 23, 2003

"All truck engines (V6 and V8) in Chevy trucks have been dubbed "Vortec" since 1996."

Actually I would emgaine that it even goes further back then that. My 94' has "Vortec" on the heads, and a fellow I go to school with has the same stamp on his valve cover to his 5.7L Extended Cab. A did a little research on the net, and I found that 1990 was actually the first year for that bodystyle. I would emagine that from 90-98 they called em all Vortec motors.

OUMike · April 23, 2003

I read a history thing on the C/K, and I was wrong. 96' WAS the first year for the motors being called "Vortec". The valve covers on my 94' also are stamped Vortec..any thoughts?

bassdog · April 23, 2003

The 4.3L was dubbed Vortec in 94 I believe...maybe back to 93, not sure. The 5.0L and 5.7L were changed in 96.

CMNTMXR81 · April 23, 2003

"All truck engines (V6 and V8) in Chevy trucks have been dubbed "Vortec" since 1996."

Actually I would emgaine that it even goes further back then that. My 94' has "Vortec" on the heads, and a fellow I go to school with has the same stamp on his valve cover to his 5.7L Extended Cab. A did a little research on the net, and I found that 1990 was actually the first year for that bodystyle. I would emagine that from 90-98 they called em all Vortec motors.

The 4.3L V6 has been called the "Vortec V6" since it was put into an S chassis truck in mid 1987. The Vortec name was placed on ALL engines (V6 & V8) as of 1996. There was no Vortec V8 prior to this. Period, nada, end of story. Up till 96, the only "Vortec" motor was the 4.3 V6. The only valve covers to have "Vortec" stamped on them were the V6's. These Valve covers were a centerbolted composite plastic. The V8's just had centerbolted stamped steel valve covers (the never had composite plastic valve covers). And the heads do not have "Vortec" engraved on them anywhere. If you find a set of heads themselves with "Vortec" on them, I want them!!!

Here are two pictures of my 1995 Vortec V6. Note the second picture with the valve covers, these are the only ones to ever have "Vortec" stamped on them.

Engine

http://www.chevy4x4trucks.com/CMNTMXR81/Vortec%20V6%201.jpg

Valve Covers

http://www.chevy4x4trucks.com/CMNTMXR81/Vortec%20V6%203.jpg

The Vortec name was derived from the swirl and tumble design of the combustion chamber forming a "Vortex" I suppose. This form of combustion chamber design was attached to V8's in 1996 and power jumped commensurately. usually 30-40hp.

Hmm...
So that means that because the current performance motor for GM in 98' was the LS-1, and the LS-1 and Vortec share NOTHING in common...there is pretty much no way to interchange internals.

NO, no, no!! The LS1 was it's own engine in 1997 & 1998. It was used ONLY in Corvette's (97+) and F-Body's (98+).

At the same time in 1997 and 1998, GM trucks still used the old school SBC V8, those being the Vortec 5000 and 5700.

When GM let lose the new 1999 Silverado, that new Silverado THEN incorporated the new Vortec motors (4800, 5300, & 6000) that are based on the LS1.

Also in 1999, the old body style Tahoe's and Suburban's still used the Old SBC (Vortec 5700). So this year (1999) there were a total of 6 Vortec V8 engines available throughout GM's lineup. Those were;

Vortec 5000 (old school SBC)

Vortec 5700 (old school SBC)

Vortec 7400 (old school BBC)

Vortec 4800 (LS1 derived)

Vortec 5300 (LS1 derived)

Vortec 6000 (LS1 derived)

The LS1 and LS1 derivatives components ARE NOT compatible with the previous gen SBC components.

As to modifications available, the old school SBC has one of the largest aftermarkets in the world available to it. 3/4's of the Summit catalog is devoted to small block and big block Chevy's. The new LS1 derived motors are still growing, but they are growing fast.

CMNTMXR81 · April 23, 2003

Also, on a side note, there were two generations of Vortec V6's to be used in trucks.

From mid 87 to mid 93, the base Vortec V6 which was a TBI motor and the 8th digit an "X" was rated at 165hp & 225lbs-ft of torque. It had centerbolted stamped steel valve covers and obviously a TBI unit on top.

In mid 1993, GM made some improvements to that V6 gave it VIN# "W" as the 8th digit. It's major upgrades included CPI (Central Port Fuel Injection), some internal upgrades and then can be differentiated by the CPI intake and composite valve covers. The picture above I linked to is a "W" motor. In 1995, GM added a counterrotating balance shaft to smoothen things out a bit. Then in 1996, they dumped the problematic CPI system in favor of SFI as well as made it OBDII compliant. I believe the also made some block improvements to improve rigidity. The 4.3 soldiers on in it's 96 format now in Astro vans and the base V6 in Silverado's.

Tucson_02Silverado · April 23, 2003

CMNT, wasn't there a short time an HO variant of the 4.3?

OUMike · April 23, 2003

okay...

So here is what I've figured based on the info I've learned.

1) the 5700 in the 98' is NOT interchangeable with the LT-1 due to different Generations, with the LS-1 being the current motor.

2) that same 5700 is NOT interchangeable with the LS-1 either.

3) even with the 2 above statements, there are several aftermarket internal parts made by other aftermarkets made specifically for the 5700 series motor.

These are the 3 major questions I was looking to have answered. Does that sound accurate?

Another thing I wanna touch on is gas mileage. How will the 5700 perform in relations to my 94' 4.3L? I've been told by serveral pretty reliable sources that the 4.3L was one of the more ineffiecient motors to come from GM. I know its the not the appropriate way to measure MPG, but I have been getting about 300-310 miles to each tank. I recently (within 30,000 miles) changes PCV valve, plugs, fuel filter, air filter, and it runs smooth. 310 per tank isn't TOO bad, but I would hope that the EFI V8 would do much better. Any insight?

SilveradoWV · April 24, 2003

First off, there is an HO 4.3L, it could be identified by the VIN letter (not sure what 2 letters are for HO and regular). I am not sure if they still offer a non HO 4.3L it seemed like HO's were popping up in any 4.3L not just 4x4s and such which originally got the HO, which isnt much HO IMO!

As for the gas mileage question, I have had a 4.3L in a ZR2 Blazer and a EFI TBI 350 in a K1500. The 350 got about an average of 5-7 mpg better. I feel that this is due to the fact that the 4.3L engine had to work harder to keep the vehicle at a certain speed than the 350. Therefore getting better gas mileage from the 350. Not sure if thats correct for everyones cases but it seemed correct for my driving style!