LS1/LS2 Conversion

[Chickenbone]

I am not really knowledgeable with the later model vehicles. I am fairly young with an ol' skool mindset. When gas prices began their assent in '01 to where they are now, I began wondering about modding my '78 Malibu for better mpgs. At first I thought about getting an Edelbrock Pro-Flo EFI system, 3.73 Grand National rear, and a TH200R4 OD for the 305. I shoulda gone with that, but I ended up putting the stock rear, 2bbl carb, and taller tires for highway cruising (college and work). At some point I began to realize that the junkyards began getting later model vehicles in them. Hence the subject line of this thread. (sorry for the long story)

I began pricing 6.0L engines out of the Silverados and what I think are the LS2s out of the Cadillac Escalades. I figured that I would get the truck ECU and wiring from one of those vehicles, the transmission, and whatever other computer related things I needed for the Malibu. My Malibu had a toasted wiring system (I was told that the curcuit for the dash was a flimsy ribbon that would break after X amount of years), so I would have no inhibtions to ripping the dash apart for the truck wiring or whatever aftermarket wiring harness that I need to make this work. I saw that they had motor mounts for LS1/LS2 engines in Summit Racing for G-Body Monte Carlos. My father is a sheetmetal fabricator, so he said he could make a trans mount if he had to. The driveshaft will have to be modded or custom made for the engine/trans combo. I think I will have to get a GN rear out of Speedway; I forgot which rears were compatible for these cars (3rd gen Camaros or '84-'92 S-10s). I used to cut the tech articles out of Chevy High Performance magazine about G-Body mods, but I lost them sometime between moves. I will have to get a new gas tank and plumb in larger lines and fittings, possibly an in-tank electric fuel pump for the fuel system. Headers, I could go with block huggers until I can figure out which LTs to install. Other than that, this is all new to me and I don't know what I will be getting into. If there is anything missing, the plan is totally wrong, or somebody here has done this, please let me know.

The reason for this thread is to give my friend some options for her (was mine, read my new user thread) car when she gets the original equipment up and running again. The original 305 took premium gas (did you guys see the prices :evil:? ) because I think the heads were carboned up from many years of service. My plan is to do the aforementioned swap on her car (since it ain't that nice anymore) and look for a better car (better exterior) to put all this stuff into when the time comes. She is into older G-Bodys, F-Bodys, and muscle cars and won't settle for anything less. I figured that a later model engine out of a big SUV would get better MPGs in a lighter vehicle (even with an auto trans) like the Malibu, pass emissions easily, and get better overall performance than the original equipment. Thanks for your time reading all of this crap and I hope to hear from ya .



Chickenbone

 

[85 Cutlass Brougham]

Well, I have an unpopular opinion about LSX engines. I do not think they pay off in a pure cost-benefit analysis. I think they are great engines, and worth considering if you are doing a swap, but the added cost will take a long time to offset the savings (if any) in fuel costs. So, with that being said, what is to be done? A traditional SBC can produce good economy and reasonable power that is close to what you can get with a LSX, but with a carburetor and an old HEI. You need gearing that strikes a balance, a cam, head, exhaust, compression, carb, intake, etc. combo that gives you plenty of low to mid range torque while operating at a low enough RPM at cruising speed as to not require a lot of throttle input. For a carb, a properly set up Quadrajet is the best choice for economy and performance. For a cam, you will want a wide lobe separation angle to trap low RPM cylinder pressure and increase efficiency at low to mid RPM's. The heads should not be too large in their port size as this would kill low end. So, nothing larger than a 185cc intake runner. Low compression is a bad thing too. Higher compression will be more efficient up to the point of detonation, which brings us to peak cylinder pressure. This is actually what you want to manipulate, and it is changed by the cam and compression ratio. A lower compression engine, for example, can generate as much peak pressure as one with a higher compression ratio if the cam's timing events trap more pressure. This is why big cams lope more in a lower compression ratio engine than a higher one. The lope is part of poor combustion due to lower pressures. Of all the older engine designs, the SBC is the best one to make work with a variety of parameters simply because of the massive availability of parts. Anyhow, that's enough theory for now. There is another post somewhere on the pros and cons of the LSX engines that was done in the last week or so, and you may want to read that as well. I think it was about how to drive a G body with $4 gas.

Also, many states do not permit the installation of a light truck engine in a passenger car due to more lenient emissions controls that are employed in trucks vs cars. Oh, and the Quadrajet gets better fuel economy than a 2 bbl.

 

[megaladon6]

it's not too bad of a swap from what i understand. if you get the 4L60e trans you can just get the 700r4 x-member. and it'll fit the trans tunnel.. you will need a fuel pump capable of 60psi. you may need to use the GM pump since some are variably controlled by the ECM. you will not want the truck ECM program. but they can just be reflashed to a performance car program (and the torque limiting system turned off). make sure you have the entire harness, the fuel lines/regulator, everything possible. you will need all the O2 sensors hooked up and the MAF. the best thing to do would be to buy the car the ls came in and bring it home until you are done. IIRC you will have a/c compressor fitment problems, possibly other pulleys/accessories. and some cars need specific oil pans to clear the subframe.
the ls is a great engine and gets pretty good mileage. it's also a bit lighter than a GEN1 especially if you get the aluminum block. don't forget to look at the ls6 engines too.
good luck!
also go to pro-touring.com/forum and ask them. some of those guys are EXTREMELY knowledgable and have installed ls series engines into many different bodies.

 

[megaladon6]

and if you use the 4l60e you will need the controller for it.

 

[skullmaster427]

i'm w 85 Cutlass dude, i'm halfway on a lsx/6 spd and its mostly for power even that mpg inst that bad, but i think for what you have already i would go vortek head and tpi, what i used to have on my el camino before the lsx, keep low rpm and good trans/rear set up u will be fine

 

[85 Cutlass Brougham]

I will also add that the biggest problem with a 305 is not the small bore, it is the 2 valve heads. The use of a 4 valve head would fix the flow issues and make much better power. My 2.4 liter 4 banger has a 3.75 in stroke-same as a 400 Chevy Small Block, yet it makes 143hp and around 150 ft lbs of torque. Why is this important? Well, a 305 has a little more than double the displacement with a 3.48 in stroke, so the bore is smaller in the 2.4 liter than the 305, yet it makes similar horsepower. The 4 cylinder though has a 4 valve head on it, so it has plenty of flow for the small bore diameter. In addition, a smaller bore allows for a much tighter squeeze on the mixture for a more complete burn, and lower emissions as well as better fuel economy. This is the real problem with older V8's, they need a big bore to make decent power. It's also why the 302 Ford is a better engine for performance than a 305 Chevy, it uses a 4 in bore with a 3 in stroke.

 

[skullmaster427]

older? i still dont undertand why wouldnt gm not give us the gift of ohv on the lsx i sure would love to see dohv on a 6.0 w 32valves, one think that ford did right, at least

 

[85 Cutlass Brougham]

Well, GM did give us an OHV engine, just not OHC. Plus, don't forget that Ford's mod motor is still a 2 valver unless you opt for one of the 4 valve engines, or get a very new one with 3 valves per cylinder.

OHV= Over Head Valve. Pretty much anything with the valves in the head. In other words, Flat head Fords need not apply unless they have a set of ARDUN heads, or other OHV conversions that were (and some still are) available during it's heyday. Also, 2 strokes need not apply either, nor may Rotaries (Wankel engines).

OHC= Over Head Cam. These engines may have one or more cams in them. If it is a single cam, it drives both the exhaust and intake valves. They may be either 2, 3, or 4 per cylinder with a single cam. A good example of a SOHC 4 valve engine is the Honda D series, or MINI Pentagon engine. DOHC engines may be 2 valve as well, but with one cam driving intake valves and one driving the exhaust.(Some have as many as 5 per cylinder a la the VW 1.8t) A good example of this would be the engine in a Lotus Cortinia (or LoCort as they are also known) from the mid 60's which basically used a Ford Cortinia as the base, but Colin Chapman tuned the engine for better performance. It was also used in the Lotus Elan and I think the Europa as well.

 

[Vern]

Chickenbone, The post was "$4 gas & your gbody" its in the general discussions forum. It was about building / doing a gbody swap to perform AND get decent gas mileage. An LS swap was one of the things discussed with some detail and cost questions along with a link for an LS swap kit that included motor mounts and an oil pan. But not headers or fuel system etc.

Like 85 Cutty, due to the cost, amount of fabrication, parts & difficulty of the swap the LS swap may be less appealing than hoped. At least for the average hot rodder that has a more average amount of money time and tools/skills to accomplish the swap.

Depending on your performance/mileage goals like 85 Cutty an older engine with the right setup ie overdrive, lockup, fuel injection or carb choice, proper cam & compression, I think will meet most peoples goals easier and with more affordability. Although I see no reason a sbc has to be chosen in fact in my signature you can see two cars/setups that exceed his on both mileage and performance. That said its not at all a slam on his setup as I am sure his was acquired and setup up cheaper than you would expect to find / do a Grand National/turbo Buick conversion. Likewise he may have set his up for less money than my Cadillac powered g-body although that was a very power to cost effective swap. Well that and its a hell of a lot more fun to drive.

 

[Chickenbone]

It sounds like the LS1/LS2 swap is more suitable for a project or test car that you're not driving and can take apart and reassemble repeatedly. I read the $4 gas and your G-Body thread and see the other little devils that can haunt me with the gen3 SBC swap. I'll probably go with a mild 350 SBC build and see what kind of fuel injection I can get with it, or learn how to properly tune a carb. My friend is dead set on older cars and V8 motors. I'll just have to make multiple setups and compare them to see what will best suit her needs. Either way, I'll prob'ly end up working on that car again. Thanks for the input guys/gals. I wish I had found this site years ago.



Chickenbone