I'm at a severe crossroads here. I'm almost done with my first motor swap ever in my late-model Eclipse. I've done a TON of work to it, rebuilding the whole motor (it's my first), porting and polishing the heads, port matching the intake and exhaust, a ton of other stuff. Soon I'll be reflashing the ECU to run the larger-displacement motor and that'll be a first for me also.

When that's done, it's time to move onto the Camaro

As she sits, she's a '91 RS 305/T5, nearly all stock. I got her for $300 with a bad fuel pick-up hose. All I've done is standard stuff: open air element, ultimate TBI mods, DIY AFPR, and that's about it. I've got a set of headers sitting on my porch waiting for me to get done with the Ecipse so I can start concentrating elsewhere.

So, the tired old 305 just doesn't cut it. There's no way my V6 eclipse should be faster than an American V8, so it'll be time for a swap in the next year.

I've been reading, reading, reading on various swaps and am torn between doing an LT1 swap or a vortec swap. The goal is 350-400+ rwhp, fuel consumption is not a concern, and it's got to be visually emissions-legal. So, nothing short of (even if dummy) A.I.R. and cat, the whole 9. This will be a weekend street car but needs to be able to be daily driven if need be when the eclipse goes down for maintenance/mods. No matter which engine, I'll be upgrading the rear end, suspension, and getting some subrame connectors. I also plan, no matter which engine, to do a port/polish and rebuild the heads. I also plan on installing a cam and related valvetrain upgrades. I'm debating still on whether to rebuild the bottom end.

Anyway...

If I do an LT1 swap, I'd source the motor from a junk yard, retrieve the entire wiring harness and ECM, and leave the tranny there unless it's a manual. I don't know yet if I would get a painless harness or try to use the old one. I don't know if I'd trust the bottom end as I've read that the crank can be ruined by thrust beaing wear. I'm also unsure how difficult it would be to tune using stock injectors. I've also never jacked with optispark or reverse cooling.

If I do a vortec swap, I'd likely keep a TBI setup using a vortec-specific intake bored for a big block TB, then doing all the standard stuff to that TB. This would also be source from a junk yard. That way I could pretty much leave the wiring and such alone. What I'm worried about is how difficult tuning may be with this setup. Despite my research Im kind of at a loss for how I'd even go about getting started since I don't want to burn chips.

Deciding factors (listed by priority)

1. COST. I don't have an exact dollar amount, but the $2000-2500 seems close to what I have in mind. (this is also why we're discussing LT instead of LS)

2. Ease of install. This goes along with cost. If I've got to buy a bunch of accessory brackets or have stuff fabricated (other than PS and fuel lines), it'll cost more. Otherwise I don't mind working.

3. Ease of tuning. I'm aware that I'll need to invest in hardware (cables, WB o2, new chip?, etc) and software in each option, but which would be the more user-friendly?

The old T5 needs a refresh as well. Can it be built to handle more power?

 

First you need to decide whether you're going to stick to your budget or your hosepower goals. You can't have both. You're not going to get 400RWHP for $2500.

The only time I see an LT1 as cost effective is if you're going to get a cheap junk yard motor and install it as-is. If you're going to mod it (and you will be if you want 400RWHP), the LT1 is no longer a bargain. LT1 parts are somewhat rare compared to SBC or LS parts, and they're expensive. Plus, once you get into replacing heads, the LT1 no longer offers any power advantage whatsoever compared to a SBC. SBC has more heads to choose from, and power potential is likely better with aftermarket SBC heads due to a lot more continuing improvements and R&D.

I would eliminate an LT1 from consideration and focus your decision making between an SBC or an LSx.

Between those two, at the power level you're aiming for, your total involved cost will wind up being more or less a wash. To get 400RWHP from a SBC, you're really looking at a large cube stroker with good heads, upgraded valvetrain, cam, etc. To get 400RWHP from a 6.0 LS, you're essentially talking about a cam swap. However, putting that LS into your car will incur considerably more cost than the SBC because you'll need the right mounts, right headers, right accessories, etc.

As for ease of install and tuning, both of those are going to relate to how much money you want to spend. Any of this can be easy if you buy an aftermarket self-learning EFI setup, but that costs money. If you want to take a more grass roots approach, then sticking with a carbed SBC is probably going to be the easiest. For the LS, the easiest will probably to go carbed too, but that ultimately winds up costing as much or more than going with the EFI, and can influence your transmission choices.

From an actual fitment standpoint, the SBC is the clear winner. It just drops in, and will bolt up to any T5, 700R4, TH350, TH400, Powerglide, LT1-T56, etc. For the LS, you either need to deal with adapters, or go with an LS-based 4L60E or T56. If you decide to retain the factory LS EFI, going with a 4L60E is easy because the computer & harness will control it. If you go carbed, you'll need an expensive external controller for the 4L60E, so it becomes a lot less appealing. You could still use a 700R4 or a manual trans though. As for manual transmissions, a T5 will never hold up to 400RWHP. It might hold up to 300 for a while if you don't hammer it, but if yours needs freshening up, I wouldn't bother pouring any money into it. You should immediately start looking for a T56, but of course which one depends on which motor you choose. The LT1-style T56 is what you want for an SBC or LT1 swap, and the LS-style T56 is what you need for an LS swap.

Piece of cake.

 

Thanks for the input!

And yeah, neither the HP goals or budget are totally set-in-stone. But I'm keeping the budget low since I take a lot of time searching local classifieds and the junk yard for deals. Truthfully with HP goals I'd probably be happier at the 300hp mark than 400 for driveability, but I'm aiming high. I haven't ruled out boring/stroking, raising CR, etc. but these things do cost. As a caveat I have no qualms with doing as much of my own work as possible. There are actually deals on full motors but then I can't say I built it.

So far vortec seems very viable for ease of build, but induction is the main concern. I'm a fan of the LT MPFI but as you said, parts are rare and expensive. I'd hate to use the TBI bacause of its limitations.

If it were up to me I'd just throw an aftermarket EFi system on it (too expensive) or carb it (would never pass inspection). So, keeping in mind it's got to be some type of fuel injection but there is a budget, it makes things much more difficult.

I'm interested in the T56 as well but they're a little harder to come by. I'm not going automatic no matter what. Now, a lot hinges on what pops up at the yard too when the time comes. If I come by an LT1/T56 combo, it'll all be decided then and there. I'll do what I can with porting/cam/headwork and be fine with that.

 

If you want to go with EFI, TPI and the Holley Stealth Ram are going to be your cheapest options. You can get a full stock TPI setup for a couple hundred bucks, but the stock setup will severely limit you on power, and on a Vortec-headed motor, you're going to have to shell out another $400 for the intake. Based on that, the Stealth Ram starts to look pretty good. You can get the Vortec Stealth Ram for around $700-750, and all you'd need to add would be a TPI harness, sensors & computer (and a tune obviously). Keep in mind that on your TBI car you'll also need a new fuel pump, and maybe fuel lines.

 

Yes on the fueling, I'm aware. But those are a given.

Exhaust is stock as well, but that'll be done while it's still a functional 305.

I'm keeping an eye out for aftermarket systems that are used so maybe I can find one cheap. Getting a TPI harness wouldn't be too tough actually. These things do hit the yards from time to time. If this doesn't pan out, however, it'll be a matter of checking against what's out there in classifieds land and what's out there in the yard come time to get started. That's one of my few advantages: not being dead-set on the exact way I want to go about this. It's kind of what pops up, but any and all input is appreciated and may serve to steer me in one direction or the other. Another advantage is time: I've got too much going on to start the build which gives me some time to weigh all options and get started right.

 

Not sure how in the world the Gen1 sbc is being listed as a more cost effective setup for the power goals in mind.

An LT1 at that level will cost less, and be far easier to select components that will get the job done. If theres one spot where the LT1 is the best for $/HP its in the 300-420rwhp range.

I'll never understand the "LT1 parts are rare, or not as supported" side of things, who cares if you can get 10 different intake manifolds and 20 different sets of heads ? Its been well proven the stock heads ported from one of several well proven suppliers will put down 390-440rwhp depending on your cam choice, you dont need 20 different intake choices to pick from, you dont need 10 different bin choices for the prom, or any of that other nonsense.


The LT1 will bolt right in place, takes the same header options you'd need/choose from with a gen1 sbc, your T5 isnt the greatest choice for a lot of power, but there are mixed opinions and mixed results with them, for your budget you should be able to easily install an LT1 setup as well as a cam/valvetrain package. That will get you in the 340-360rwhp range, a set of ported heads will take you into the 400+ range.

 

I think he was talking more in reference to, say, an LT4 upgrade which I know are discontinued which totally sucks. And really, 400 FWHP would be great but I have no idea what kind of powertrain loss these things get. Besides, all that matters is what the wheels put down.

At any rate, I think I could settle for a TBI build on a vortec platform but I feel it's leaving too many cards on the table and not giving enough room to tune. I sure wish I could throw a carb on and call it good, but that won't happen unless I look for an older model Camaro. Being as I got this one for $300 I'd like to end up with around a $3000-$4000 13-13.9 second car. It's doable but will take me a while.

I still can't seem to decide on a direction haha.

 

The LT4 'upgrade' is pointless looking at the power levels you can get with Advanced Induction's ported heads and intake. The LT1 stuff can make the power you're looking for. I'm not trying to sell you on LT1's, just pointing out the LT1 is well capable without getting any 'rare' items.

 

I see. Either way though, I plan to port whatever stock heads I get. Purchasing new heads would cost double what the motor itself would. That's why I'm looking in the realm of LT1/vortech, because the heads are much better than any stock GEN I SBC heads and (from what research I've done) show really good numbers ported, or even not.

 

400 rwhp is what I was referring to.

400 Flywheel HP just requires a cam upgrade in an LT1.

Just getting whichever engine you happen to run across will probably result in shooting yourself in the foot performance wise, especially if you're willing to go with a TBI setup.

Also using the engine as a reference point for purchase price of cylinder heads is a bit silly, and again will only hurt you more than it will help you. Porting on a set of LT1 heads will run you $1400-1800 when done, but you doing them yourself will come nowhere near the same potential.

If 400HP at the flywheel is your goal, an LT1+cc306 cam will get you there, set out to find an LT1 for the right price and install it with the proper stuff, you'll easily get there, and wont have to play any silly games. You'll also still have the option later to have the heads ported and break into the 400RWHP area.

 

Thanks for the cam suggestion. That was another thing I wanted to get into later, maybe even once I decide on what engine to go with. But ALL info is appreciated.

I'm getting pretty good at porting work but will in no way claim to be able to do what the machine shop guys can. However, the only way to get there is to practice. If I end up a few hp short of what they can do, it's still a free improvement over stock.

And honestly, even at 300 rwhp, that's double what it's got now which I know I could do with either choice. And if staying in budget that's a pretty good deal. Of course I'd rather have a good deal more though.

Leaning more towards an LT1 for now...

 

Yes you *can* do it with either setup, its making much beyond that where you get a diminishing returns effect with the other choices, thats why I said for up to 430ish rwhp, the LT1 is a great choice, above that or right around that range the LS1 starts to be beneficial opposed to the LT1, but realistically I havent seen much for actual results out of a vortec efi setup that would compete with an LT1 $/$. If you are willing to take your time, do some learning, learn to avoid those who are starstruck by LS1's, and those who have no experience with optispark's yet preach about them, you should be able to learn that putting one in and getting mid 300rwhp is easily within your budget.

If 430+rwhp without spray is what you want, go for an LSx based swap, or if you can get a great deal on something complete for a swap package. If you are fine with a 400Ish rwhp setup that wont break the piggybank, the LT1 is a great choice.

 

Things that will make for a complete LT1 swap in your car, or rather what you NEED:

Engine harness: This needs to be combined with your existing harness, or another, the LT1 F body harness doesnt place the PCM in a great location for the swap honestly, it works fine if extending it to place the pcm under the dash like stock, the caprice/roadmaster/impala harness works nice for a thirdgen swap putting the pcm in the battery tray area drivers side front, doesnt need any extending for a nice fit and finish.

Fuel lines: The TBI hardlines are fine up to the engine bay, you'll need new lines, or to make some to go from the fittings near the shock tower over to the LT1 fuel rail.

Power steering: The PS pump on the LT1 non Ybody accessorys is on the passenger side, you need a pressure hose meant for this, several solutions have been done, the low pressure return and mounting of the reservoir is also needed, but a simple task.

A/C: if you are keeping a/c then you'll need to notch the engine crossmember and make or have a set of lines made.

You'll also need to upgrade the fuel pump (you'd need this with a tpi, HSR, or any other port injection setup)

The LT1 will bolt right in with your existing mounts.

The T5 will bolt right up, the vss is of a different type than what is typically used with the LT1's pcm, you've got a couple choices here, its possible to use the stock setup, and take the output of the tbi buffer box, feed it into a dakota digital and then use that signal for the LT1 pcm, or if you can get into a V6 T5 from a 4th gen you can take the vss reluctor and vss out of it to use in your thirdgen T5, then just use the LT1 pcm vss output to drive the speedometer.

 

All that is very doable. Vss from a v6 T5 should be easy to come by as well. I'm assuming the f body lt1 would be the better candidate or does it really make a difference? I know the heads are aluminium in an f body saving some weight and the cam is different which doesn't matter since I'm not keeping it anyway. But are there other differences I'm unaware of? I ask because it would be easier to pull the harness with the motor. However, extending it would not be an issue for me. I actually enjoy that type of thing.

 

Yes i'd aim for one from an Fbody, shame you arent close i've got one sitting with several upgrades i'd let go cheap at the moment.

Extending 80ish wires, properly isnt anything to be "enjoyed", i've done numerous harnesses and seen plenty that other people have modified, to make changes or complete them, and honestly havent seen many that are actually done right, properly, etc.

Since you arent in a hurry, go hunting at the jy like you're already doing, and if you spot a bbody engine harness before the engine, grab it, if you get the engine first, so be it.

 

Lol. I'm an electrician.

 

An automotive electrician ?

 

The worst: a navy electrician haha. But I've got residential, commercial, naval, and automotive experience. Redid the whole wiring harness on my current swap in addition to years' worth of cutting, splicing and all other manner on many makes of vehicles. Some boat stuff too.

 

Might actually come out ok then I suppose.

At any rate, wanting to make 80-160 extra connections over using the bbody harness doesnt make a lot of sense.

 

Very true. Sounds superfluous given the option so long as I can find all I need.

Food for thought...