Ok I have searched through and seen many threads for an LS1 swap, but can not find the answer I am looking for. Can someone who has done this swap answer the K-member question for me.

I talked to Bruce Hawkins today (hawksthirdgen) and he said that I would have to change out the K-member in order to use the A/C on the LS1. Is it hard to change the K-member? If I do choose not to change out the K-member, will it just drop in (other than changing the motor mounts)?

I am real close to buying the LS1 motor I want, I just wanted to insure I am not getting to deep into something I may not be able to finish. I know I can do everything, except not sure about the K-member.

Thanks in advance,

Scott

 

Stock K-Member has to be notched to clear the LS1 Air Conditioning compressor.

 

any ideas as to how or wqhere to notch it? easier to notch it then to replace it? the next thing I will do after the LS1 is STS turbo it Matt.........lol

 

You wont know exactly where to notch it until you have the motor at hand.

Unless you really like the AC id recommend getting an AC delete box. The rear spark coil on the LS1 will rub on the AC heaterbox as well, and will need to be relocated, youll also need custom AC lines id imagine.

Turbos are fun.. drove mine for first time today. Soon as that turbo spools.. the tires start spooling too

 

i'll try to help as much as i can. i wa in your shoes a few months back!
theres a couple thngs you can do:

a few companies out there sell a bracket kit that will raise your a/c and alternator to the top of the motor. with this set up you an use that basic sawp mounts and you wont have fitment issues. pros to this one is that it will be pretty much bolt on, con are its expensive as ****.

Swan or Spwan performance (forgot how to spell it) came out with a tubular k- member which will replace you oem one. check i out i would def. consider this route. its light weight and just fits awsome (product cam eout after i did my own k-member) dont know what the price is.

or you can take the route that i took and notch your own k-member.
you would have to cut a few inches in and re-weld a plate for support.
htis is def the cheapest way to go. only con is that you have to take your time on makeing the mounts because you can have fitment issues in other areas. ( for example, my engine sits 2 inches foward and i had to add those 2 inches to my drive shaft) no big deal, but just a heads up.
here are the pics:






hope they can help. any questions feel free to ask me. i had tons of questions my self while i was doing it! in my opinnion, DO IT! the car feels like a monster!! i through in a stock ss camro exhaust and trust me know one knows what it has under the hood! she has some shitty tires and she still tore up a brand new hemi charger last thursday. hopefully that will pump u up for the swap. hahhahahah. good luck!
-Lou

 

the kmember bolts on and off with 6 bolts. no big deal.


now you can buy the kmember, or notch your current one.

theres more info on this with a search.

 

ok I have the K-member figured out...thanks guys. Now that I know it just bolts in and out, I will be buying the SPohn tubular one and going thta route.

Next question:

What do I do about the wiring harness and PCM? How do get it to work with my ignition and work with my speedo and such? I may be over thinking this, but I am just wondering how it works. The engine I am buying has the harness, but no PCM. I talked to painless wiring and they have one with PCM, fuse box and all that, but will it hook to my existing ECM to make the speedo and all work?

Thanks for the help guys, I am buying the engine tomorrow then have to make plans to go get it. Then I have to buy the accessories and brackets. Once I have it completely ready to go, then I will have to find the T-56 and swap it all out. Then comes the installation....should eb fun and I am looking forward to it.

 

I did this swap, too. I went the route of the "expensive as ****" and purchased the F-body motorsports AC kit.

It was expensive and it took a few weeks to receive as it's a custom fabricated to order it. also- I had to file down the edges and notch the holes to make it work. It needed massaging to fit. Also- the belt vibrates terribly when running the AC. There's a long distance between the pulleys. I fear it'll pop right off. I hate it. Makes me not want to run the AC it shakes so bad.

If I were to do it again I'd get that tubular k-member like everyone is stating and retain the 4th gen compressor. I may still do that one of these days. I eventually want to upgrade my LS1 and get more power.

My point is you're making the right choices here.

The LS1 swap itself is well worth it. much more power and lighter weight, better economy, everything. It will be well worth it.

As for intergrating into your car the wiring kit should have wires labeled for where they need to hook up. The kit/ wires should be labeled where to hook up the 12 volt power source, the switched power, the tach, speedo, etc. you should not need your old ecm for your old engine. it should be removed. but don't randomly yank wires. only cut what you absolutely don't need after you're sure you don't need it.

If possible try to completely remove old unneeded wires so you don't have random hot wires that don't go anywhere that can create electrical gremlins down the road.

Things like your lights and such are not involved with the ecm. they're part of it's own wiring system to the car and may only have a few wires at most that may cross over. (things like the constant and switched power sources to run the ecm)

My car came with a mechanical speedo and since the LS1 transmissions use a digital signal- I swapped my speedo. I think the later 3rd gens had a digital one so it may be able to hook up. This I can not say for sure.

I made my swap as easy as possible by using as much from the 4th gen donor car. I used the fuel system including the tank, the exhaust, everything. I used a modified 4th gen engine harness from the donor car. I had speartech modify it. this way all the plugs fit where they were designed and it plugged into the fuel system etc.

I am also using a painless kit in another car of mine. Again, it has the wires labeled as to where they need to go. It's for the most part painless.

Just remember that not all the LS1 signals etc are compatible with the 3rd gen stuff. You may need to buy some compatable gauges/ senders to make your gauges read correctly. Example- My 4th gen gas tank and 3rd gen gas gauge are not compatable. Neither is the temp or oil sender on the ls1 engine to the 3rd gen gauges. At least the earlier ones. My voltage gauge works, though...

Just my experience. I hope it is helpful.

 

thank you for all this info guys. This is seeming more and more simple to me. Seems all you have to do is have the money for the parts and go from there.

So I guess I will have pigtails to tap into my original harness huh? I am just trying to picture it, but like you said painlesswiring makes it painless.........lol

Do I have to change out all my fuel lines? Will my tank be ok? What lph Fuel Pump should I have? I am guessing I will need a special driveshaft for the tranny to go to my stock rearend. I will eventually change it to a fourth gen rear, but I want to get the engine and tranny in first. Is there a way of knowing what sixe I need before I install everything, or do I need to measure it out afterwards?

Now for T-56 questions. I am seeing where an LS1 T-56 must be different than an LT1. Is this correct? If so than that means I need an LS1 T56 crossmember....correct? Is it dificult to go from AT to T56? Such as mounting the pedals and the hydraulics and such? I have seen links on here for how to do it to your L98, but this is an LS1.....but I am assuming it would be the same way.

 

as for the wiring part of the swap:

i have heard a of a few comanies who make you the harness and ecu to plug and play (meaning you wire like 4 wires and just plug the rest in and ur done!)(the 4 wires are: ground, 12v, ignition, &fuel pump) ( their haness even gives you and OBD2 port, a wire for your check engine light) i went with the street and performance setup. yes, it was pricey. but im glad i payed for it beacause it was truly plug and play.
you will not use your oem ecu/pcu. but do Not remove your oem harness!
now as for your gauges:
you need to decide if you want to sawp to auto meter or other brand or keep the oem gauges.
i kept my oem gauges. Street & performance leaves you labled wires that come out of the ecu to the gauges. i got thos wires and taped directly into the harness in the engine bay to get all my gauges to work. with the exception of 2 of them (tach and speedo)
tach all you need to do is get a tach signal interface which changes the pulse/signal to correct it to read the ls1 tach. (like 30$ on ebay)
your current speed is cable driven from the tranny (mine was) the ls1 is electronic driven. to make this work you need to purchace a speedo conversion box and cable. (got mine from TCI automotive) also plugs right in (this one you'll have to actually plug to the back of your dash.
or you can buy the rear housing on your tranny and replace it to drive your cable driven speedo. (street and performance)

 

Going by your username, I'm going to assume this is being done on a 91....

I did the wiring myself with the help of an electrical engineer freind. We spliced the LS1 harness into my existing 91 harness because I was not about to give someone 700+ bucks for something that is simply not that hard. It took us a couple of weekends, and then a few random days to chase down some gremlins, but we did it. All my stock gauges work perfectly. You do not need a tach adapter, I don't know why someone above said that. Simply plug the tach signal wire into your gauge, if it is off, then you need HP Tuners to set the correct pulse, in my case, it was 3. The speed-o on mine just happened to be right since I had the same rear end gear and tire sizes that the original donor car had, otherwise, if it is off, you will need to adjust the various settings in HP Tuners to get it right, you can adjust tire size, and rear end gear ratio to get that perfect.

The voltage gauge will work as is, as will the oil pressure guage. The Water temp however is a different story, the original L98 sensor is a 1 wire, the LS1 is a multi-wire and does not use the typical signal we are used to. What I did was buy another stock thirdgen water sensor (they are made of brass), and I used a bench grinder to make the overall size of the threaded area smaller, then tapped it with the correct threads to fit in the LS1 head. So technically I have 2 water sensors, one for the PCM, and the thirdgen one for my dash.

As for the fuel tank question above, you can use your stock tank, and your stock lines, you will however need to upgrade your fuel pump to a 255, Hawks sells them. You will also need to get an adapter (or make one) to hook up your stock lines to the fuel rails on the LS1, I got mine from fbodymotorsports, but I do not recommend them as a company. If you want to take your chances with them and have plenty of time to wait for them, call them and remind them, etc, then give them a try (also, tighten the fittings before installation to avoid spraying fuel all over the place like I did, thanks FBM).

I hope that helps....and remember, if you are asking, its most likely been asked before, the search feature will bring up lots of info....

 

i agree completely with everything he just said.. and i did the same thing.

 

"Do I have to change out all my fuel lines? Will my tank be ok? What lph Fuel Pump should I have? I am guessing I will need a special driveshaft for the tranny to go to my stock rearend. I will eventually change it to a fourth gen rear, but I want to get the engine and tranny in first. Is there a way of knowing what sixe I need before I install everything, or do I need to measure it out afterwards?

Now for T-56 questions. I am seeing where an LS1 T-56 must be different than an LT1. Is this correct? If so than that means I need an LS1 T56 crossmember....correct? Is it dificult to go from AT to T56? Such as mounting the pedals and the hydraulics and such? I have seen links on here for how to do it to your L98, but this is an LS1.....but I am assuming it would be the same way."

The other guys say you can keep your fuel lines and tank, so I'd listen to them. My swap was from an earlier carburated model so I had some different pieces which is why I used the 4th gen stuff. Either way will apparantly work.

Regarding your rear axle- no, you can use your existing driveshaft or you can use a 4th gen LS1 aluminum driveshaft. They are interchangable. I installed the LS1 driveshaft in my car before I even performed the LS1 swap. It fit right into my old 700R4 trans...

For the third gen rear there is little benefit IMO to swapping to a 4th gen rear. The ring gear diameter only changes from 7.5" to 7.625" a marginal increase in strength. Also, while it will directly bolt in it has wider axle tubes so your wheels will stick out further.

So, unless you're using deeper backspaced rims or need the brakes or something, I see little beneft, if any, in doing this. People with 4th gens blow up their rear ends also. I think you'd be better off buying an aftermarket 12 bolt or 9" for your car, especially if you plan on upgrading your LS1. Otherwise leave your stock 3rd gen rear in there, especially for now.

For your transmission- the bellhousing on an LS1 T56 is different than an LT1 bellhousing and I believe the input shaft length is different, but this has nothing to do with the crossmember. You will need a crossmember designed for this swap. If you know someone who can weld they can build you one, or you can buy one. I bought mine from F-body motorsports (and waited 2 weeks for it) only to receive a beat up box with my parts hanging out of it (not necessarily their fault but good packing reduces this from happening, too). I've heard of a "Drew's crossmember" that has been designed with exhaust clearance in mind. I'd recomend getting one of these.

BTW- if anyone knows where to get one l of these?? I want one too.

I had to cut a hole in my transmission tunnel for the manual shifter to fit and then mount the manual pedals in my car for this. It's not hard. A dremel or similar cutoff too (sawzall, etc) and a little measuring will do the trick.

I used 4th gen pedals from an LS1 car for mine. I've read that the LS1 pedals are needed because they have the proper leverage/ throw for the LS1 clutch hydraulic cylinder. If you use LT1 or 3rd gen pedals they need modification to achieve the full travel needed. (a search will provide this info. I remember reading it elsewhere on this site)

Also- the 4th gen pedals have the gas pedal bracket tack welded on. you can leve this on (pita, as I learned the hard way) or cut it off and use your 3rd gen pedal assembly as is.

At least on my car the carpet and insulation had a die cut punch out of where the clutch cylinder had to go. I used this to locate and drill mine. With minor finessing it worked. Hopefully, yours will to.

The biggest pita for me with this swap was the exhaust. I wanted to retain all the emissions equip including the 2 cats so I had to have some custom exhaust work done on my car. They relocated the cats to make them fit in my car better and made custom exhaust tubes to make everything fit. It sits low and I have to be wary of speed bumps, etc. Another reason why I'm interested in that "drews" crossmember so I can re-do my exhaust right this time (a learning experience for me)

Again, I hope this is helpful.

 

no.yeswalbro 255. aka the standard replacement no. stock is perfect. driveshafts are identical length, and ends.it doesnt change. they're almost the same. clutch actuation is diffrent.. input shaft diff. but overall,they are the same trans. no. the same crossmember. depending on your mounts, you may have to slot one trans mount hole back some... hawks uses the same spohn T56 crossmember as teh "lt1" trans. its almost identical. just be sure to use a set of pedals from an LS1, and be sure to mount the master cyl in the correct spot. yup. all you need is atleast one pressure capable line for the fuel to get there. stock ones are nice because they fit the car easily.


i screwed up the quoting, but i think im going to post it anyway.. lol

 

yep, you did