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Old 10-04-2014, 07:45 AM   #1
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BoxsterLS376 introduction - LS3 conversion :)

Greetings Boxster friends!

My name is John and I'm addicted to projects~

I have been around the Porsche scene for a bit now mostly working with 911's & 944's, and currently work for a small restoration shop in Marietta, GA called Check Point Auto. I recently finished my last side project so I need a new one to keep me from getting fat and lazy... If any of you are into older air-cooled cars you know that the Porsche market has gone completely nuts and finding good classic project cars for a good price these days is just about impossible!

So I was surfing the auction sites, Copart actually on this one and came across a Nice little 2000 Porsche Boxster S that had "Mechanical Damage". Right up my alley, i'm not a bodywork guy. Well this one appeared to be in good overall condition, Grey/grey and a bit of a sleeper as it didn't have a Boxster "S" badge on the back... (Now that I have it not so much a sleeper as it has a 2 FT long "BOXSTER S" sticker on the spoiler, oops )

I always liked the Boxster but personally think the 2.5 has no guts whatsoever and the 3.2 is merely adequate at 250~HP...Project wheels set in motion!!

I got the car, coolant was a bit oily but oil looked OK and so I fired it hoping for the best and... Fired right up! No crazy IMS noise or anything, so far so good! Car appeared to have a new water pump and t-stat so I was hoping a new oil cooler would take care of everything, put it on and ran it for a few days only to find that now not only was there oil in the coolant, but coolant getting into the oil WAH WAH WAHHHHHH So I figured it probably needs a head gasket at minimum, probably a cylinder head and who knows what else... i've been doing this long enough to know it can be a very slippery slope!!

Needless to say I'm not very excited about fixing the motor that is in it, so I think we should make it better

BEGIN PROJECT BOXSTER LS376-480!!! Unlike some people while being fairly mechanically inclined I am no rocket scientist and would prefer not to reinvent the wheel - I'll just use someone else's!! If all goes well I plan to use the car as somewhat of a shop demo car with the possibility of doing these conversions for customers in the future... While I'm sure you could probably do this conversion cobbling parts together and buying used stuff that's just not my style - that being said, here's the plan!


I have ordered a Renegade Hybrids conversion kit with all optional parts... in reality I'm not sure why they list this stuff as optional unless you are building a race car, but whatever~

Power will be supplied by a LS376-480HP GM Crate motor with Hot Cam! IMHO this is the only way to go, shopping around I can get the whole power plant with new harness, gas pedal and a few other bit I need for about $8,000. Not cheap but consider buying a used LS1, rebuilding it, adding more HP etc. you will still be in it for $5-6K... plus with the crate motor I get a 2 year warranty!!

Factoring in the car, the conversion kit, the new motor, fabricating an exhaust and a few extra parts I have set a budget of $20,000 for the whole project which will likely go over because I will probably upgrade some other bits along the way but that's a pretty solid number.

Well the kit should be here in about 3 weeks so I have gone ahead and pulled the 3.2 from the Boxster and am looking forward to sharing this project with you all!

Sorry for the long winded introduction!!!
John







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Old 10-04-2014, 09:48 AM   #2
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There will definitely be some interest in a proper LS conversion. What people will be interested in is how it will integrate with all the existing systems without unacceptable compromises at a reasonable cost. So far there really hasn't been anyone that has done this to my knowledge. Good luck.
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Old 10-04-2014, 10:30 AM   #3
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I want to watch this. I see you are in GA, i'm in AL so I want to see how this goes.

WOuld love to see it after you have finished
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Old 10-04-2014, 10:59 AM   #4
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Watching this, sounds an awesome project. Would be interested on how you are going to fit it all in.
Are you going to use the original transmission.?
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Old 10-04-2014, 12:05 PM   #5
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Thanks everyone,

It will definitely take a bit of work, Renegade says about 70 hours for the install but we will see about that.

I definitely want the car to operate as it would if Porsche would have done it themselves which is why I ordered the Electric power steering, electric water pump etc. because otherwise compromises would have to be made elsewhere.

It does utilize the factory transmission which I'll probably crack open and take a look at while it is out to make sure there are no outstanding issues but it felt fine. I also ordered the upgraded clutch kit as they told me the stock clutch would "work" but would likely slip so no freaking point it putting it in if you know it's not gonna work :/

Integration is my biggest concern as I would like all the factory gauges to work. While it seems like Renegade has the mounting of the motor worked out I'm not feeling overly confident right now with regards to instructions on doing it all as I keep getting told they "have lots of pictures"... hrm... we will see!

Thanks!!
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Old 10-04-2014, 02:40 PM   #6
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best wishes and good on you!

I believe Renegade has done many a 996....very similar gauge pack to the 986. There seems to be very few issues in the gauges working there so hopefully you will be fine

How did you decide upon the LS3 rather than 6 or 7. I guess things to consider are: chassis twist/strength; drive line durability; handling and max tire sizes; drivability; suspension. I would think anything over 500 BHP would be very hard to make use of and scary in a boxster chassis
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Old 10-04-2014, 04:24 PM   #7
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I wish we could get a look at some of the directions for this kit ?

I hope you can share some of that with us without any legal infringements
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Old 10-04-2014, 06:41 PM   #8
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Looking forward to your progress! Thanks for sharing your project. Good luck and welcome to the forum
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Old 10-05-2014, 07:33 AM   #9
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best wishes and good on you!

I believe Renegade has done many a 996....very similar gauge pack to the 986. There seems to be very few issues in the gauges working there so hopefully you will be fine

How did you decide upon the LS3 rather than 6 or 7. I guess things to consider are: chassis twist/strength; drive line durability; handling and max tire sizes; drivability; suspension. I would think anything over 500 BHP would be very hard to make use of and scary in a boxster chassis
Yeah I am hoping everything works out, mostly just rewiring some things and adapters for certain sensors etc. but keeping my fingers crossed.

My engine choice was not really based on chassis twist or anything like that as they have a 600 HP LS7 in one and although I don't know the long term effects, seems to handle the power fine. Basically came down to several things but after running through the options it really made sense... let me share my logic...

1. Used LS1 - good motor but low mileage ones from a vette run about $4000 with harness, you could get one from a Camaro then your down to 305 hp and barely worth the effort. I would rebuild and clean it and of course try to get more HP out of it while it was out, figuring I'd probably spend another $1k-$2k easy doing that plus all my time...

2. LS7 Crate motor - Great motor, fantastic internals forged titanium goodness, but the dame thing only makes 505 HP and costs $12,000 so just didn't sit well with the overall project budget.

3. LS6 - old Z06 motor based on LS1 - again too expensive for what you get, people get a premium for them simply because they were only in the Z06.

4. LS3 Crate motor - Brand new, 2 year 50,000 mile warranty, plug in the harness, add gas and go - no time spent rebuilding. 430 hp from the standard motor, but add the GM hot cam and you get 480 HP for about $7500! 25 HP less then the LS7 but $4,000 cheaper! A bit more expensive then rebuilding and modifying a used LS1, but no time spent, brand new and has a warranty!!!

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I wish we could get a look at some of the directions for this kit ?

I hope you can share some of that with us without any legal infringements
Heh, yeah well if I get some instructions with it i'll let you know!! As I said I have asked a few times now about this and have been told that they have lots of pictures... sooo not really sure what to expect but I'm certainly not going to publish anything here unless they give me the OK, but i'll be glad to ask.

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Looking forward to your progress! Thanks for sharing your project. Good luck and welcome to the forum
Thanks Bruce! Nice to see a community of Boxster enthusiasts which seems to be fairly active. I'm on Pelican, LS1 tech and a few others but this seems much better. I'll definitely keep you posted on progress!
Thanks!
J
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Old 10-05-2014, 09:45 AM   #10
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Look forward to watching your progress

Thanks for sharing your project. Great choice on the hot cam edition seems like the best deal per pony. Good luck and can't wait to watch your progress.
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Old 10-05-2014, 10:32 AM   #11
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Originally Posted by BoxsterLS376 View Post
Yeah I am hoping everything works out, mostly just rewiring some things and adapters for certain sensors etc. but keeping my fingers crossed.

My engine choice was not really based on chassis twist or anything like that as they have a 600 HP LS7 in one and although I don't know the long term effects, seems to handle the power fine. Basically came down to several things but after running through the options it really made sense... let me share my logic...

1. Used LS1 - good motor but low mileage ones from a vette run about $4000 with harness, you could get one from a Camaro then your down to 305 hp and barely worth the effort. I would rebuild and clean it and of course try to get more HP out of it while it was out, figuring I'd probably spend another $1k-$2k easy doing that plus all my time...

2. LS7 Crate motor - Great motor, fantastic internals forged titanium goodness, but the dame thing only makes 505 HP and costs $12,000 so just didn't sit well with the overall project budget.

3. LS6 - old Z06 motor based on LS1 - again too expensive for what you get, people get a premium for them simply because they were only in the Z06.

4. LS3 Crate motor - Brand new, 2 year 50,000 mile warranty, plug in the harness, add gas and go - no time spent rebuilding. 430 hp from the standard motor, but add the GM hot cam and you get 480 HP for about $7500! 25 HP less then the LS7 but $4,000 cheaper! A bit more expensive then rebuilding and modifying a used LS1, but no time spent, brand new and has a warranty!!!



Heh, yeah well if I get some instructions with it i'll let you know!! As I said I have asked a few times now about this and have been told that they have lots of pictures... sooo not really sure what to expect but I'm certainly not going to publish anything here unless they give me the OK, but i'll be glad to ask.



Thanks Bruce! Nice to see a community of Boxster enthusiasts which seems to be fairly active. I'm on Pelican, LS1 tech and a few others but this seems much better. I'll definitely keep you posted on progress!
Thanks!
J

Makes perfect sense to me and 480 seems like it would be workable top end for the chassis. Looking forward to seeing your progress, costs, and work. Hopefully the LS3 isn't too heavy as compared to the 3.2
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Old 10-05-2014, 11:33 AM   #12
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Are they close ?

This shouldn't be too hard to find out..what are the net weights of each ?

Renegade says they are very close....but they are also selling the kits !!
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Old 10-05-2014, 01:48 PM   #13
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This is exactly the thread I have been waiting for. I talked to Scott at Renegade Hybrids a couple of months or so ago about doing the same swap in an S. The choice of the LS3 does seem to be the sweet spot. Weight wise the difference is almost negligible. Performance wise you will have the power of a Porsche Turbo with LESS weight, the reliability of a small block Chevy (bulletproof), same or better fuel economy (who cares) and the handling of a Boxster. Done right, you will have an incredible, no compromise car. Sure, purists will give you a hard time, but they already look down on 986s, so who cares. For the price of building another disposable M96, you will have a super car.

I have concerns about a few details with the swap. First off, with this swap you leave in the original engine ECU (DME, whatever you want to call it), and share the crank sensor with the GM ECU. That keeps the gauges and immobilizer happy. Kind of kludgy IMO, but it works. I guess you just remove the check engine light, as the Porsche ECU will have LOTS of faults in it. I have been researching a bit on how to eliminate the Porsche ECU, but that would be a big project. I like to have things super clean, and I wish there was a way to either "teach the GM ECU to speak German", so to speak, or get the gauges, ABS and alarm/immobilizer to work without the Porsche ECU. The first option would be the cleanest, the second the easiest (IMO). My business is automotive electronics, and this stuff is right up my alley. Ideally, I would want to use a normal Corvette ECU so you would have a car that doesn't throw any fault codes and could go through emissions without any issues.

Second, I'm not sure why they don't use the original power steering pump or a different mechanical pump. I guess that will become apparent as you get into it. There is nothing wrong with using the electric pump (probably Toyota MR-2 setup I will bet), but it is added complexity. From a "cleanliness" point of view, I don't like this detail. I think I would get over it after a few stop lights though.

Next, the intake. Keeping everything under the original engine cover seems to be an issue. Turning around the intake manifold so that the intake is at the back is a no brainer, but that also doesn't leave much/any room for the throttle body. That needs to be adapted to turn 90 degrees if you want to keep the intake from going into the trunk.

I think you will also run into some issues with the driveshafts as it looks like the transmission will be moved back a bit. I bet Renegade has a solution.

If you want some good ideas on how someone else made a "short" LSx conversion, here is a link to an Audi RS6 that got a LSx engine. They the same issues with that conversion that you will have with your Boxster.

I can't wait to see how this progresses.
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Old 10-05-2014, 08:19 PM   #14
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This shouldn't be too hard to find out..what are the net weights of each ?

Renegade says they are very close....but they are also selling the kits !!
Yeah I'm sure they are not too far off, LS3 weighs in at 466 pounds, can't seem to find a weight on the 3.2 off hand, but I'm sure it's a good 400+.

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This is exactly the thread I have been waiting for. I talked to Scott at Renegade Hybrids a couple of months or so ago about doing the same swap in an S. The choice of the LS3 does seem to be the sweet spot. Weight wise the difference is almost negligible. Performance wise you will have the power of a Porsche Turbo with LESS weight, the reliability of a small block Chevy (bulletproof), same or better fuel economy (who cares) and the handling of a Boxster. Done right, you will have an incredible, no compromise car. Sure, purists will give you a hard time, but they already look down on 986s, so who cares. For the price of building another disposable M96, you will have a super car.

I have concerns about a few details with the swap. First off, with this swap you leave in the original engine ECU (DME, whatever you want to call it), and share the crank sensor with the GM ECU. That keeps the gauges and immobilizer happy. Kind of kludgy IMO, but it works. I guess you just remove the check engine light, as the Porsche ECU will have LOTS of faults in it. I have been researching a bit on how to eliminate the Porsche ECU, but that would be a big project. I like to have things super clean, and I wish there was a way to either "teach the GM ECU to speak German", so to speak, or get the gauges, ABS and alarm/immobilizer to work without the Porsche ECU. The first option would be the cleanest, the second the easiest (IMO). My business is automotive electronics, and this stuff is right up my alley. Ideally, I would want to use a normal Corvette ECU so you would have a car that doesn't throw any fault codes and could go through emissions without any issues.

Second, I'm not sure why they don't use the original power steering pump or a different mechanical pump. I guess that will become apparent as you get into it. There is nothing wrong with using the electric pump (probably Toyota MR-2 setup I will bet), but it is added complexity. From a "cleanliness" point of view, I don't like this detail. I think I would get over it after a few stop lights though.

Next, the intake. Keeping everything under the original engine cover seems to be an issue. Turning around the intake manifold so that the intake is at the back is a no brainer, but that also doesn't leave much/any room for the throttle body. That needs to be adapted to turn 90 degrees if you want to keep the intake from going into the trunk.

I think you will also run into some issues with the driveshafts as it looks like the transmission will be moved back a bit. I bet Renegade has a solution.

If you want some good ideas on how someone else made a "short" LSx conversion, here is a link to an Audi RS6 that got a LSx engine. They the same issues with that conversion that you will have with your Boxster.

I can't wait to see how this progresses.
The wiring will be interesting, you sound like a handy guy to know for this sort of project! I am going to try and make the install as clean as possible, but getting the Porsche and Chevy ECU's to jive will be the hard part. It would be nice to eliminate the Porsche ECU but not gonna happen without lots of work. The guys at Renegade say they can make it all work so I'm going to lean on them quite a bit when it comes down to it.

The steering pump is one of those "optional" things which is not really optional if you want to have the power steering. No room for a standard PS pump on the motor, I'm sure it could be done but in an effort to save space they do use a Toyota electric power steering setup. I just hope it doesn't make things feel funny but I think it will be ok.

I went out to visit and checked out the intake setup. They are working on a custom 90* piece which we route back into the stock airbox so it pulls cold air. Of course it is not included with the kit so time to dust off the ol' welding skills and put them to the test Not to worries about keeping it under the original cover as additional bit will have to be cut just to accommodate the throttle body and intake, I'd like to come up with a plexiglass or lexan lid for it to show off all my hard work - to far away from that to worry about it right now!

Axles are a concern but they do not have a solution just yet... I know the cheap Chinese axles are pretty cheap though so I may just stock up on a few sets

Thanks for the feedback and link to the other thread, I know I'm going to need some help with this one!
Take care,
J
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Old 10-06-2014, 06:24 AM   #15
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I'd like to come up with a plexiglass or lexan lid for it to show off all my hard work - to far away from that to worry about it right now!
You might be interested in this:

Rear Storage Shelf mod ideas
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Old 10-07-2014, 11:42 PM   #16
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Old 10-08-2014, 03:11 PM   #17
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I assume you've seen the other topics on this. Here is a post from when I was out in Nevada visiting Renegade...

Renegade Motorsport Corvette engine in 986! WOW!
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Old 10-16-2014, 06:19 PM   #18
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When do you expect your parts to arrive from Renegade? So looking forward to this project build.
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Old 10-16-2014, 08:34 PM   #19
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Fun project! Scott is a friend of mine and he has done a bunch of 996/986 conversions now. The chassis is talking to the motor just fine on them so you should have no problem with that. Toyota 12v PS and WP are the only way to go. The LS3 is certainly a tight fit but doable and it is a sweet powerplant with monstrous torque.

You may be able to use a Cayman engine cover to fit over your intake. It is a little taller and some have done this successfully. Forget a plexi cover. The way a Boxster breathes by pulling air up from the road surface makes the engine compartment look like a nasty chicken coop after about a week of driving. It ain't pretty and this is actually part of the ground effect in addition to cooling the accessories, trans and rear brakes.

I have considered this conversion but Nazi emissions regs in Comiefornia make a street conversion risky. I would have to register the car at Scott's house in NV and run the CHP impound gauntlet while living here in CA. Too much PITA for me unless it was a dedicated track car.
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Old 10-16-2014, 09:34 PM   #20
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Fun project! Scott is a friend of mine and he has done a bunch of 996/986 conversions now. The chassis is talking to the motor just fine on them so you should have no problem with that. Toyota 12v PS and WP are the only way to go. The LS3 is certainly a tight fit but doable and it is a sweet powerplant with monstrous torque.

You may be able to use a Cayman engine cover to fit over your intake. It is a little taller and some have done this successfully. Forget a plexi cover. The way a Boxster breathes by pulling air up from the road surface makes the engine compartment look like a nasty chicken coop after about a week of driving. It ain't pretty and this is actually part of the ground effect in addition to cooling the accessories, trans and rear brakes.

I have considered this conversion but Nazi emissions regs in Comiefornia make a street conversion risky. I would have to register the car at Scott's house in NV and run the CHP impound gauntlet while living here in CA. Too much PITA for me unless it was a dedicated track car.
How is the drivability and handling of the Boxster with the LS3 if I may ask.......I guess one feathers the throttle to get back to where it was originally as far as traction and balance....would you need a huge leep / amount of seat time to handle it? Have wheel widths been changed..square? I have been on track in a Cayman R (I think the engine was stock) and found that to have just an insane amount of momentum.....well it was the old Mosport, lots green and yellow traffic, R comps....anyway it felt way way over my head even in the power department.

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