When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Engine SwapEverything about swapping an engine into your Third Gen.....be it V6, V8, LTX/LSX, crate engine, etc. Pictures, questions, answers, and work logs.
Ok first I have a tired 305 and want to swap it out for a little more power. This is a 100% street car and will never see the track. I'm torn on doing a Vortec 5.7 or a 5.3 LS swap.
Vortec 5.7 swap with the stock TPI upper and a SDPC lower. I'm at the point it will be hard to find one to just drop in without a refresh. I figure I'm going to be in it at the cost of $1000 at a minimum especially if I need head work and an overbore or I find a cracked head. The SDPC lower is $400 and then I will need larger injectors to support the additional displacement $250. Mild cam $200. I can use my stock 700r4 without a problem until it explodes.
I would be in it $1850 plus fluids and BS.
If I went with the 5.3 LS I could probably find an engine that does not need rebuilt. I would purchase and entire donor from Copart or Iaai. I have done a few different budgets but I should be in it around $3000 on the low end and $4000 on the high end. This would be with a mild cam also. This would be swapping over to a 4L60E. This would be a much more involved project because of the wiring, accessory drive, oil pan, fuel pump, and so on.
I know people are happy with the LS swap. I can't find much real world info on the vortec tpi swap. If people are happy with it for the amount of work.
Personally, I wouldn't try to keep TPI on a 5.7 with vortec heads. With the larger displacement, cam swap, and larger injectors, you're going to need to do some tuning (either buying the equipment yourself or paying someone to do the tune). Vortec heads don't have the same EGR provisions, so you'll need to either figure out a workaround or delete EGR from your tune. Don't forget to factor in that cost, the additional time, etc. Depending on what year your TPI setup is, it may be more difficult to work with. I'm not an expert on this but I believe the older years have less powerful/flexible computers and are more difficult to tune. I don't know what year your car is, but in your shoes I'd start researching to make sure you won't run into additional costs there.
FWIW I was in about the same position (wimpy 305, wanting to swap up to a larger engine), and went with a 350 w/ vortec heads and an aftermarket TBI-style unit instead of trying to make the TPI stuff work. I used a Fitech but there are similar kits from many manufacturers. Expect to spend about $1000 for one of those kits, but you'll save ~$250 on buying injectors and you can sell the TPI stuff to make up some of that difference too. If you go Fitech you'll need a carb-style intake manifold for the vortec heads, but that should be quite a bit cheaper than the TPI lower (IIRC I paid ~$200 for mine). Some of the other kits come with dedicated manifolds, so there's no additional cost there.
Just my opinion though. Good luck with either swap!
I have the stuff to tune my own car and it is a speed density 92 car. I honestly have not really done much with the tuner other than re-program the injectors when I did them. I figured I could get a stock 350 bin and tune from that. I'm going to register as a classic this next go around so I can ditch the emissions testing and the need for an EGR valve.
I wrestled with the same dilemma when I bought my current "87. I ended up going with a 5.7 over the vortec because my car is a manual the total cost all in was more then I wanted to spend for a new motor, trans, and driveshaft. I also just flat out like the look of the TPI and really don't care if it doesn't run like a race car.
In the end I went with a stock, low mileage 5.7 out of a tahoe managed by a FAST EZ-EFI 2.0 retro kit. I had a speed density TPI setup and added the plenum to a set of SLP siamese runners mounted to a SDPC lower. I also bought a set of Accel 30lb/hr injectors. With that being said I had to rewire my engine bay due to rodent damage, and if I didn't care about the TPI look I would have just done a 4bbl vortec base with a FI-Tech, or similar, management system. So far I have not been happy with the FAST system I bought due to it being really picky and not wanting to recognize the handheld used to tune. If I keep having issues I am going to rip it all out and either go with a Holley Sniper setup or build a custom setup using one of the existing LS or Vortec ECUs I have.
Also being in Nebraska i don't have to worry about SMOG testing.
By $4k you mean $8k . Budget more for either swap although the Vortec one will likely be less in the end, albeit with less power.
Items that must be addressed for either option that must be in your budget.
Fix broken and lazy suspension parts, strongly recommend subframe connectors.
Brakes MUST be upgraded, this is more important than power.
Either swap will require a full exhaust from the headers back.
Either swap will require ECM tuning (either EPROM for TPI or dyno tune for 5.3).
Either swap will require fuel system upgrades.
A cam swap for either will cost $800 + by the time you add in new lifters, timing set, gaskets, etc.
This is just small list of items that you must consider which will easily eat away at your budget. You'll often find the engine is the cheapest part of the swap.
By $4k you mean $8k . Budget more for either swap although the Vortec one will likely be less in the end, albeit with less power.
Items that must be addressed for either option that must be in your budget.
Fix broken and lazy suspension parts, strongly recommend subframe connectors.
Brakes MUST be upgraded, this is more important than power.
Either swap will require a full exhaust from the headers back.
Either swap will require ECM tuning (either EPROM for TPI or dyno tune for 5.3).
Either swap will require fuel system upgrades.
A cam swap for either will cost $800 + by the time you add in new lifters, timing set, gaskets, etc.
This is just small list of items that you must consider which will easily eat away at your budget. You'll often find the engine is the cheapest part of the swap.
All of that can be done "cheaply".
My LS1 brake upgrade was just the brackets and hubs from bigbrakeupgrade, everything else (I mean everything) came from a donor car in the junk yard.
Suspension... Most guys are just fine with some new shocks and new bushings in everything. If you want to lower, cutting springs is an option.
Subframe connectors are a given in these cars.
You don't necessarily need a new exhaust depending on what is already in the car... And you can easily build your own system for a couple hundred bucks.
Tune for a stock LS transplant? All you need is the ECM flashed to operate for the swap correctly. Not a dyno tune.
Fuel system, not a big deal. I bought a 4th gen tank with the pump still in it. It's feeding my cammed LS1 no problem. Again, cheap.
He doesn't need to do a cam swap... Especially with a 5.3 LS, I think he would be happy with it as is, especially coming from a 305.
OP, my vote is a stock 5.3 LS swap. Find a truck for cheap (I bet you can find one for $1500) take what you need out of it (engine, trans, harness) and then part/junk the rest of it. You will enjoy that so much more than a 305, the reliability and fuel mileage is great. A harness isn't that hard to build. When you are tired of that power, you'll have saved up enough for the cam and supporting parts.
SO here is my plan just because it dropped in my lap. I'm picking up a super low miles vortec that has developed a rod knock. They want $100 for it. It was well maintained from a shuttle bus that drove employees around a campus. The heads look really clean with no sludge and hopefully no cracks. I was also able to score an entire Scat 383 assembly for peanuts. The guy sold it to me for $350 and included a bunch of parts I'm going to sell to make up some money. So I guess I'm building a 383 tpi motor. I hope I can use the heads basically as is. Just deck them flat and upgrade the springs for a little more lift and re-grind the valves. The block will need some love to bore it out to 4.030 for the new larger pistons.
I have done a basic refresh on the suspension already. The car is a Vert and has subframe connectors. I have a walbro 255 for additional fueling. I feel like the stock TPI is going to be a big bottle neck in this setup but I also don't care. This car will never go above 4k RPM anyway.
When I first did my LS1, I went through this, I had a worn out 305 that would vapor lock, would blow smoke on start up. A buddy said it smelled like being behind a boat.
First thought was I'll just do a 350... Then, figured may as well do a 383. Then found this forum and learned about LS swaps and went that way. Figured stock LS1 power was enough. Nope, 8,000 km later I did long tubes, cam and some other stuff. I hope it's enough.
SO here is my plan just because it dropped in my lap. I'm picking up a super low miles vortec that has developed a rod knock. They want $100 for it. It was well maintained from a shuttle bus that drove employees around a campus. The heads look really clean with no sludge and hopefully no cracks. I was also able to score an entire Scat 383 assembly for peanuts. The guy sold it to me for $350 and included a bunch of parts I'm going to sell to make up some money. So I guess I'm building a 383 tpi motor. I hope I can use the heads basically as is. Just deck them flat and upgrade the springs for a little more lift and re-grind the valves. The block will need some love to bore it out to 4.030 for the new larger pistons.
I have done a basic refresh on the suspension already. The car is a Vert and has subframe connectors. I have a walbro 255 for additional fueling. I feel like the stock TPI is going to be a big bottle neck in this setup but I also don't care. This car will never go above 4k RPM anyway.
Big brake upgrade is on my to-do list also.
Nice!
A used Vortec 350 will easily make 450+ HP with only a camshaft, valve-springs and an intake manifold!
I built one in 2002... increased the compression to 10.6:1, cylinder head porting, screw-in studs, valve-guides machined, new hydraulic-roller camshaft and matching springs and seals, Roller rocker-arms, true-roller timing-set, Carburetor and ported RPM Air-Gap intake Manifold, MSD 6AL, coil and Distributor...
An easy aprox. 525HP at 6,600 Rpm.
They make the same power - I went for an LS swap but would not do that again.
Interesting, why do you say this? I'm honestly curious since most folks don't ever regret going LS. The swap cost is higher than staying SBC but the power is just so easy to be had.
Im stll trying to figure out how a 255hp vortec 350 can add 200+ hp easy with just a cam an intake swap?
After looking at my built LS motors over the last few years and seeing how easy easy they make power no way would I ever go back to my boring 320whp with a fully built 350.
Im stll trying to figure out how a 255hp vortec 350 can add 200+ hp easy with just a cam an intake swap?
After looking at my built LS motors over the last few years and seeing how easy easy they make power no way would I ever go back to my boring 320whp with a fully built 350.
A lot of reports out there of an otherwise untouched L-31 making ~300 once the factory exhaust and fuel system is ditched. Chevy sells a 357hp vortec based 350 that is essentially only a cam swapped L-31.
I don't know about adding 200+ hp without some serious work, but kissing 400 with a mildly worked vortec 350 seems well within the realm of possibility.
I did a quick search and found hotrod did a 355 and got 430hp with AFR heads and a lot of cash $8,000 plus.
I have done vortec 350 builds so I understand what they can do and they are a mild bump in power over the old tbi/tpi heads. My last build might have cracked 400 hp if I would have did a compression bump but again this was a set of high dollar aftermarket heads.
Even the 383 guys have a hard time getting to LS basic power levels and by this time your talking a fully built motor that still wont keep up with a LS 6.0 out of a truck with a cam only.
LS engines are no doubt superior in power and most every other way but the swap is costly. Also everyone doesn't have to have 400+ hp to be happy. If I were to buld a drag car an LS would be the obvious choice. A lot of us love the looks of the GEN1 smallblock and they have served us just fine over the years.
I honestly believe the LS platform is a better engine. I'm still flip flopping in my head mostly because the lack of good intake manifolds for the Vortec heads. I did pick up the 350 Vortec engine yesterday. It is super clean and I can't believe it has a knock.. The heads look new with no sludge what so ever. I'm going to pull it apart and go to the machine shop this week. I think I'm going with the First TPI intake manifold. That will up the build cost another $1000 and get me even closer to the cost of a full blown LS swap. I have decided to go this way because the matching vortec lower and upgraded runners will be $900. I get a bigger throttle body and a better upper designed for a TPI car for $100 more. They also are good for a few hundred more RPMS before they fall flat. Again this is a street car that will never see the track,. My wife drives it most of the time and I drive the second gen or the 3800 SC Fiero. She just cruises with the top down with the kids or drives it to her hair or nails appointment. This is the car she wanted in high school but couldn't afford. I just want it to be somewhat reliable and have good road manners.
I honestly believe the LS platform is a better engine. I'm still flip flopping in my head mostly because the lack of good intake manifolds for the Vortec heads. I did pick up the 350 Vortec engine yesterday. It is super clean and I can't believe it has a knock.. The heads look new with no sludge what so ever. I'm going to pull it apart and go to the machine shop this week. I think I'm going with the First TPI intake manifold. That will up the build cost another $1000 and get me even closer to the cost of a full blown LS swap. I have decided to go this way because the matching vortec lower and upgraded runners will be $900. I get a bigger throttle body and a better upper designed for a TPI car for $100 more. They also are good for a few hundred more RPMS before they fall flat. Again this is a street car that will never see the track,. My wife drives it most of the time and I drive the second gen or the 3800 SC Fiero. She just cruises with the top down with the kids or drives it to her hair or nails appointment. This is the car she wanted in high school but couldn't afford. I just want it to be somewhat reliable and have good road manners.
I honestly believe the LS platform is a better engine. I'm still flip flopping in my head mostly because the lack of good intake manifolds for the Vortec heads. I did pick up the 350 Vortec engine yesterday. It is super clean and I can't believe it has a knock.. The heads look new with no sludge what so ever. I'm going to pull it apart and go to the machine shop this week. I think I'm going with the First TPI intake manifold. That will up the build cost another $1000 and get me even closer to the cost of a full blown LS swap. I have decided to go this way because the matching vortec lower and upgraded runners will be $900. I get a bigger throttle body and a better upper designed for a TPI car for $100 more. They also are good for a few hundred more RPMS before they fall flat. Again this is a street car that will never see the track,. My wife drives it most of the time and I drive the second gen or the 3800 SC Fiero. She just cruises with the top down with the kids or drives it to her hair or nails appointment. This is the car she wanted in high school but couldn't afford. I just want it to be somewhat reliable and have good road manners.
The Edelbrock Vortec Performer RPM Air-Gap is an AMAZING intake manifold!
You can use a Four-Barrel style Throttle-Body with the Injectors in each runner (The manifold already has bosses for injectors or Nitrous-Oxide nozzles)...
Or use a 90 Degree Elbow with a LS style Throttle-Body and Injectors in each runner...
If not either of those, then use a TBI style system with the injectors in the Throttle-Body.
The Vortec heads will produce a healthy 420 - 440 HP without any porting... Just screw-in Studs for the Rocker-Arms and Bee-Hive style Valve-Springs that will match the Camshaft (Use of Non-Bee-Hive Springs will require the Valve-Guides be machined shorter).
A Camshaft in the range of 230+ degrees of duration @0.050" and aprox. 0.500" lift will get a 350 engine to this power level.
There are some OLD "Chevy Hi-Performance" and "Car Craft" magazine articles from the Late-1990s/ Early-2000s that have build recipes pertaining to Vortec-Head swaps.
Essentially the recipes consist of:
-350 engine with at least 9.75:1 compression ratio.
-Stock L31 Vortec-Heads that have the Rocker-Arm Studs replaced with Screw-In style Studs.
-Bee-Hive Valve-Springs
-A dual-pattern hydraulic flat-tappet or hydraulic roller Comp-Cams Extreme High-Energy Camshaft with approx. 0.500" lift and duration of approx. 230 Degrees @0.050".
-Edelbrock Vortec Performer-RPM Air-Gap Intake Manifold.
Easy 420 - 440 HP.
Head porting and valve-job along with more compression and more camshaft can bring the HP up to approx. 500 HP without getting expensive.
The reason that the LS (SBC Gen III and Gen IV) builds are very often recommended is because the Cylinder-Heads on these engines will support 500 - 600 HP stock or mildly ported!
Very difficult to pass on a stock engine ready for 500 - 600 HP!
I was thinking about doing a standard dual plane like the Edelbrock VortecPerformer RPM Air-Gap. If I did something like that I'm basically ditching the stock computer and going to something like the Fast XFI? I know the TPI will dictate the power curve more than anything else.
I have no reason to give my wife a 500 to 600 HP Convertible. I do not have enough life insurance on her for that. LoL!
I was thinking about doing a standard dual plane like the Edelbrock VortecPerformer RPM Air-Gap. If I did something like that I'm basically ditching the stock computer and going to something like the Fast XFI? I know the TPI will dictate the power curve more than anything else.
I have no reason to give my wife a 500 to 600 HP Convertible. I do not have enough life insurance on her for that. LoL!
That would work, but hood clearance under a stock hood with that manifold might not be enough. Would have to measure, or search around to see what others have done. If it's an issue, then a standard dual plane Edelbrock Performer might be a better choice since they are closer to the height of a stock 4bbl intake. The dual plane intake and aftermarket throttle body injection system would work well for a 383 build.
It really depends on your goals, budget and how much work you want to do though. If you are saying that this car is for your wife to cruise around town with kids, how much horsepower is really needed? I know, I know, more is better, but if you brought your goal down to around 300hp, the project gets a whole lot simpler and less expensive. With the right gearing, headers and a nice-sounding cat-back exhaust, the car would be a whole lot of fun to drive. If the low mileage L31 motor you have is easily fixable (hopefully just machine the crank and replace the main and rod bearings), put it back together with a mild cam (L98, LT1, LT4 or maybe a ZZ4), SDPC lower base, stock runners, 350 injectors and a tune. Simple, low cost swap, 100hp gain over stock, sounds good and fun to drive. Just another thought.
I'm with you. I just want a good little car for her to drive around in. She is not going to race it. She may light them up from time to time are take a hole shot off a light to 45MPH. I keep trying to tell myself this is not my car. I have a fast car already and don't need another one. I would be completely happy with 300 HP. I have thought about doing a ZZ4 cam or the XFI 260.
The block and heads came back without any cracks. We are boring the cylinders .040 over. We are decking the heads and block surface flat. The machine shop is installing new cam bearings for me. I Should have the rings and bearings this week to start assembling the rotating assembly this week.
We just picked it back up from getting the new top on it. We are going to have the entire interior recovered in a few weeks after I get some punch list stuff done.
The XFI 260 is a good cam, but has a lot of lift and even with the beehive springs in the Vortec heads, max lift is in the 0.525" range, unless other machine work is done to the heads. The ZZ4 cam lift at 0.474"/0.510" will work with the Vortec heads without additional machining of the guides and spring pockets, as long as you do the beehive springs. Also, screw in rocker studs would be a good idea.
Car looks great. Going to be fun cruising around with the kids and the top down.
02-01-2021, 02:54 PM
. Budget more for either swap although the Vortec one will likely be less in the end, albeit with less power.
