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.
Nice^, what did you use for ECU? Custom tune? What did use for wiring harness? Whose motor mounts? What exhaust manifolds?
terminatorX ecu. Tuned myself (not hard to do). Wiring harness came with the termX system. Moto mounts are eBay cheap solid SBC bolted to ICT billet engine adapters. I used eBay SS long tube headers for a 82-92 firebird/Camaro. These were left over from my LS swapped firebird that went turbo. They are Racing innovations brand and cleared the steering box and all that no mods. I do run a poly trans mount since I have solid engine mounts. Exhaust is all 304SS and less than $300 total with xpipe. Sounds pretty good with the summit stage 1 HL cam. I will eventually make my own supercharger bracket to bolt on my torqstorm centri supercharger and bump power to 650ish vs about 400 NA. I did do a champion 2 core rad, dual spal knock off shrouded fans and made my own GM 3 relay 2 speed fan controller activated by the term X. Everything adds up eventually but using the factory ECU can be a PITA trust me. Gotta depin it and convert it to standalone, invest or pay for tune which is not easy or fun… been there and done that which is why I just know im spending 1k on self tuning with boost capabilities (Holley or fitech).
Here’s a video of the first start. Remember it was setup and cranked and fired right up and settled down to a nice idle In like 20s it still has to learn and adjust the fuel and stuff so when I blinked the throttle it was literally the first time I touched it. Will get a lot better after 5 min or driving around.
another reason I did the 700r4 is that the trans can be setup For mechanical speedo so I was able to have all the factory gauges work with everything.
one thing to remember is the fuel side. I did a 82 sender with a walbro 255lph High pressure in the stock 78 tank which has the plastic liner. Then I used a corvette LS filter/regulator combo behind the rear wheel and ran a single -6 PTFe line to the fuel rails. The corvette filter regulator does both and has built in return which I plumbed right back to the tank. Without boost the fuel system should support 600hp no problem and it’s pretty cheap. $100 or so for the sender, $80 pump, $60 filter/regulstor and $60 or so
for Amazon brand PTFE hose with fittings. Throw in $50 maybe in some EFi rubber hose and fittings/clamps for the return side and your all set.
I also did drive by cable as I don’t love the drive by wire which increases the costs and getting the new pedal to fit would be a pita. With drive by cable you buy a $25 LS braided throttle cable on eBay and cut the stock carb throttle cable end off so u get the plastic part that fits in the stock pedal. Thread it on the braided line , 2 stainless washers on the firewall to fill the hole and boom fits stock with no mods and cheap. Opting for a 700r4 and drive by cable makes the term x cheaper and simpler to adapt into these old cars. I had to make zero changes to the car except I removed the AC and heater and made that my new fuse area and mount for the ECM on the inside.
rememeber even the lowest powered 5.3 made like 295-315hp which is double the stock base 350 hp rating. A simple cam swap nets you 40-100hp no other changes besides springs depending on the cam. Which puts you at 400hp reliable modern power for less than 1k. Summit cams are $260 all day and springs are like $100 or less the LS6style. I’ve pushed a stock unopened 5.3 minus cam and refreshed stock heads to 750hp at 16lbs at Every chance on my way to work, gym, food store and it just laughs it off and keeps going. The bottom on these things with the 6 bolt mains are incredible. Not to mention stock aluminum heads and plastic intakes that flow a butload for OEM equipment.
Last edited by 78vette5.3; Aug 4, 2022 at 09:33 PM.
^ Excellent, I appreciate the details, exactly what I was wondering about. LS has a lot going for it, except for the way they look when opening the hood.
Do you have any opinions about the downdraft throttle body systems and remote coil packs?
^ Excellent, I appreciate the details, exactly what I was wondering about. LS has a lot going for it, except for the way they look when opening the hood.?
When I open the hood at car shows, people stop and look at the engine and speak to me.
When I open the throttle at the drag strip, the LS speaks for itself.
^ Excellent, I appreciate the details, exactly what I was wondering about. LS has a lot going for it, except for the way they look when opening the hood.
Do you have any opinions about the downdraft throttle body systems and remote coil packs?
I think they look better. The stock or carb style engine you can't see alot and hoses/wires going everywhere. I'll post a pic of the before which was a fresh 383/th350 combo. Downdrafts look cool but can be a pain to tune/setup. A member here has one on his V12 I believe, speedmaster sells a kit though. If your looking for low profile and usable powerband your better off with a stock plastic LS6 style or FAST/MSD replacement. The cost of the dormans has skyrocketed so you might as well get a FAST at this point. No real stance on remote coil packs, they have their reasons. If you can't or need to move the coils thats fine however the stock location is very neat and keeps the coil to plug wires very short. You can get coil covers on ebay relatively cheap and more and more brands/styles are popping up all the time. Sometimes you need to move them and thats fine but I dont really see many reasons to move them as nothing is really that close and ontop of the valve covers. On my 5.3 turbo I left the coils on the valve covers with coil covers but made my own plug wires from a standard high performance SBC brand and routed them out the back and down under the turbo headers. So you don't see the wires and they don't get burned. With the stock 581 coils I have been to 16psi on 93 pump spraying 750ml of wiper fluid and never had an issue with spark and longer wires. Putting the coils somewhere else was an option but they could be near alot of heat on the pass side (turbo side) and would still need longer wires so left them stock location.
You can see the coil covers that I wrapped in 3D carbon vinyl and decals. That’s a stock NNBS truck intake (same as TBSS). Turbo has a 90 and large cone filter on it now.
Seems like the main reason to switch over to LS is the heads. But has anyone thought about instead of an LS swap, going with 18 degree heads on a Gen 1 sbc. Trickflow has 250cc 18 degree heads for $2,700 complete, about $1,200 more over a “good” set of aluminum heads. Adapters to run traditional intakes and headers another $200.
The only reason I would go this direction is headers, brackets and other mounts can get expensive switching over to LS blocks. Plus no need to purchase a new radiator or get custom hoses and your transmission will bolt up to the block and cross member.
Seems like the main reason to switch over to LS is the heads. But has anyone thought about instead of an LS swap, going with 18 degree heads on a Gen 1 sbc. Trickflow has 250cc 18 degree heads for $2,700 complete, about $1,200 more over a “good” set of aluminum heads. Adapters to run traditional intakes and headers another $200.
The only reason I would go this direction is headers, brackets and other mounts can get expensive switching over to LS blocks. Plus no need to purchase a new radiator or get custom hoses and your transmission will bolt up to the block and cross member.
Just a thought…
Not the only reason, longevity, strength and ease of maintenance and very hard to get a leaking LS (gaskets are much better). Its easy for LS motors to go 200-300k vs SBC/BBC. You also don't need a special radiator I run stock replacement champion but a stock rad will work fine too. The steam ports can be recirculated into the waterpump spacers (they come Pre tapped for that reason) if you get the 3/4" truck spacers to adapt a LS1 Fbody style pump. Same goes for Transmission... loop into the rad then to external and back to the trans.
I agree though, aluminum heads on a SBC would be cheaper and easier than an LS swap but you still don't have the modern engineering, longevity and durability of an LS.
Ive seen people take the SBC headers and cut the flange off and weld on a LS flange (rework the pipes a smidge) and you have hybrid LS/SBC headers that bolt right on for the C3. swap headers are also stupid cheap on ebay and it would be easy to adapt a $100-200 set of SS ebay headers to the stock exhaust.
The LM7 5.3L 2002 engine are practically free, they can be found in the corners of many shops and overwhelming in number from junkyards.
Turbocharged and essentially untouched they will easily 600rwhp for 200,000 miles and longer, like a factory engine, extremely reliable. My sig has an example.
As reliable daily drivers go there isn't much that can beat an older chevy truck from 02-05. Those ideal years because the electronics of Gen3 and Gen4 is simple, adaptable, very basic, easy to wire and control. Less features in the engine means less crap to go wrong, no DOD or AFM or VTC or whatever. Just the basics.
Put an LS1 intake on the 5.3L LM7/L33 and it will clear the hood. Use the OEM fuel rail "dead head" and it will give reliability of a single inlet port, without all the fittings and extraneous garbage that aftermarket rails carry.
Avoid AN fittings and use basic hose clamps to make most of the fuel system work (example in my build thread at 600rwhp track legal)
Keep factory lifters, pushrods, heads, etc... Do not port or modify the heads. The quality isnt there enough to invest the money and time of port work.
Definetely swap the cam/springs. I use TFS-30602001 and PAC1218 because this is a very slow ramp cam rate, mediocre lift, works with stock pushrods and lifters, and weak springs that will last 100k and longer mileage. Together these components support 600-800rwhp using a turbocharger fwiw so it's not like you give anything up with forced induction.
The key to valvetrain longevity is the low lift, slow ramp, weak spring as above, even if power isn't forced inducted if the goal is daily driving and low maint you need these ideas.
Compression of LM7 9.5:1 means 87 octane friendly. I've successfully 400rwhp using 87 octane and 5psi of boost. Good tuning is essential and monitoring of fuel, oil, exhaust temps is critical to getting the most safety from gasoline fuels.
Use synthetic oil obviously. CHange all the seals, gaskets, etc... use a seal alignment tool. Get the updated BARBELL from saccity corvette and their alignment tools if you can swing it. Most of the cost of the LS swap is in the small details. I recommend a budget of 15k just in nickle and dime parts.
The transmission is a touchy subject. I recommend 4l60e for low power (< 400rwhp) daily drivers but they are hit and miss with respect to junkyard pulls.
A rebuild properly will set you back several thousands. It's a tough decision there.
The 4l80e is great for 500rwhp+ But it will absorb so much fuel economy for <400 than its kind of crazy.
Some very good observations here. My small block was forever leaking or sucking air or fouling plugs. And just getting everything around it dirty. My 10 year old motor is a little dusty. As to how it "looked" new, well de gustibus non est disputandum
Use the OEM ecu with the OEM transmission (4l60/80e).
This is a kind of key, to utilize HPtuners with the original wiring harness and computer,
This is in order to maintain functional torque management. This will preserve the life of the transmission, it is critical even with a built unit I have found, if you wish high mileage and reliability from the transmission.
Aftermarket ECU rarely contain fully functioning torque management. It is worth noting whether it does or not before switching over.
The OEM 411 style ECU can support 1200rwhp~ on alcohol flex fuel through a 4l80e if desired, it is extremely robust and widely available, cheap $50 ecu, I always keep two of them as spares. The 02-07 style harness for Gen3 engines is similarly simple, robust, easy to wire, and cheap. Making this part of the LS swap affordable for EFI.
The purpose of the EFI is full control over the engine and transmission. You decide when it shifts, how hard more or less, you supplement this with internal transmission modifications 'shift kit' type of parts are often useful.
The engine side, the EFI is extremely potent for conserving fuel and maximizing power via air density and fuel timing spray.
The factory spray to a closed intake valve but we often adjust this to spray during peak piston velocity to take advantage of kinetic energy fuel spray plus this will maintain air density. All gas whether oxygen, nitrogen, or gasoline, water, takes up the same space 22.4L At STP, therefore humidity and gasoline vapors will reduce air density (carb applications or humid climates) which will reduce power. This is one reason why EFI can provide superior power output, high air gas density with low rate of vaporized fuel when done properly.
Furthermore the EFI allows full tuning air/fuel ratio, I run 15.2 to 15.8:1 air fuel for cruise/idle to preserve plug condition, keeps plugs very clean like new ,and saves fuel.
Difficult to pull this off with carb while maintaining the enrichment and transitions needed for smooth torque application.
The most important part of the entire swap IMO is the torque converter. Use a 9.5" converter from YANK , a triple lockup disc is ideal for any swap. You will thank me later for this. The 9.5" unit is efficient and lightweight, this frees up power and conserves fuel when an appropriately low stall is used. I used the 2800stall 9.5" for my 600-700rwhp swap this is ideal for daily driver up to perhaps 700~rwhp or as little as 300.
Too much unneeded and irrelevant info above. Factory ECU are robust for all the wrong reasons. Torque management is turned off 90% of the time once a tuner gets in it. I’ve always turned it off or maxed it out. Emissions crap, body module
control, blah blah blah. You need to run the engine, trans maybe, and gauges. TermX max will cover you if you want to run a 4l60e or 4l80e, if you want drive by wire get the version with that feature. You will have full control over the transmission in its intended use. OEM def has high quality and longevity locked down but a tuner can get expensive quick and HP tuners was like $750 when I bought it. That’s 50-75% cost of a Holley termX /max.
no need to Over think it (previous post). The swap is cheaper than 15k by alot depending what you do. You don’t need a $800+ 9.5” converter for a NA LS swap in a vette that will grenade the rear with any decent power.
^ All good reading and info, thanks
ignatz, looks like your carb/intake combo will fit under c3 big block hood, but, do you know for sure?
It very likely could fit but I don't have all the measurements. Right now I have a drop base and a 4" air filter so there is room, my hood is not that huge. I probably have a 3" somewhere. If you have a serious interest in going carb'd, I can duplicate these pictures. As I remember I made a mistake somewhere here when I took this picture, but what it was escapes me at the moment. I think it was that the body was not attached to the frame, but it sure is now!
If you are simply curious, well ...... it might be a while! Otherwise PM me and tell me what you are up to and if I can help.
Major change is Trans > TM: Torque Reduction Normal/Performance. No matter if the trans is built or stock, the less torque during the shift the longer the trans will last.
If you feel like you need a hard shift you have to accept that that will shorten the life of the internals.
I would not disable torque mgmt on a stock tranny if you want it to live very long. Somewhere in the 50-75% range should be OK. Post your stock file and I can make some suggestions for TCC settings and shift pressures. Leave the force motor tables alone.
I would not disable all the trans-side torque management like that even on a built unit with all the goodies in it. Trans > Torque Management > Torque Reduction only pulls timing during the shift and is a really slick way to soften the shift and at the same time keep from burning it up. The less torque the engine is delivering when a shift happens, the longer the trans will live.
If it's 'built', it should not need the pressures raised like that. If it's not, it isn't going to live long with the TM disabled.
Next, the torque converter is the heart of the swap. I would not swap any LS engine-auto into anything without a proper converter, pointless.
This is also common knowledge among experienced individuals. et al I've built and tuned hundreds of daily drivers over 25 years, my cost to setup and tune a vehicle not including labor is 5k. You get what you pay for
On my last few LS swaps I've used Yank billet converters and they have worked well. Just a single disc and 2800 stall. They drive like a stocker until you punch it. I don't tune anything but the couple tuners I have talked to and used have said some? torque management is a good thing.
My first LS/4L60E swap was a 2002 LS1/4L60E combo completely stock. The first time I drove I was shocked at the lags between shifts due the torque management. I thought there was something wrong with the trans. Took it to the tuner and he said they all shift like stock. He made it much better via the tuning again leaving in "some" torque management.
I think you can make a LS engine look good.
Couple of pics of my swaps. I try to hide every wire I can.
