Cayman LS3 Conversion

Well, here we go - it's another 987 LS3 conversion. I blew the engine on the track a few months back, just before moving overseas (Norway). So a perfect time for the car to be up on a lift for a heart transplant. I'm disappointed I won't be there to do... err... attempt the job myself. However, I've got a good shop in Houston to help me out - so they'll be tackling this one. All the big parts are in, so the project has begun. Here's the main parts/selections we've decided on: Renegade Conversion Kit, w/upgraded clutch Starting with a LS3 / 525hp crate motor from GM PP Corvette oil pan, with windage/scraper tray & accusump Cayman S transmission + cooler + Guard LSD Astra H (MK4/5) power steering pump (rumored to be same TRW pump as Porsche Motorsports... and $80) Many thanks to all the help from Fingers, Joshuaj, and others for answering my questions to help get this off the ground. The Culprit above... The work space, and the replacement.

Looking forward to seeing it all come together. Best of luck to you. What do you do about the computer? Would love to cruise with this car when she's all buttoned up! Sent from my SAMSUNG -SM-G935A using Tapatalk

Yes. Please keep us informed about the whole project and hurdles u have to overcome.

Intake reversed, clutch on...

Can you post the part number and source for the power steering pump ?

I'll try to get the part number soon. I corrected my original post as well... maybe I shouldn't type it from memory next time! It's from an Astra H, Mk4 (or Mk5). There's two models, one is from TRW - and it's this TRW one that is claimed on some forums to be the same. ~$80 is used, off ebay UK, shipped to the US. Here's the link for the one I bought: MK5 VAUXHALL ASTRA H ELECTRIC POWER STEERING PUMP / 2004 - 2010 | eBay This is a trial at this point, but will keep the thread updated if it works or not. I'm hoping to come across a true Motorsports one next time I'm home to compare as well.

Wow! Well, thank goodness there is a reasonably affordable solution out there. I assume that $4k for the conversion kit + $10k for motor + labor is still far less than the cost of a replacement motor. And it'll likely be more durable. I checked out Renegade Hybrids and the work they do is incredible. As great as Porsche motors are, they are overpriced and underpowered EDIT: Just thought of this, but what do you do for the exhaust system? Custom job?

We'll see how 'reasonably affordable' it is at the end. Granted, I've got a lot of extras going in... but don't underestimate all the bits & pieces that add in to a project like this. For me, I'm dumping money up front, with the hope that the future it will pay off. (ex. Replacement engines at 1/4 the cost.) However if money was what drove me to the decision, I would have probably just sold the car and cut my losses. This is a car I love, and will soon truly be 'my' car. Exhaust will be custom, you can see a good example in Finger's thread. I'm not entirely sure how extreme we're going to go yet for mine.

What are your thoughts on LS3 low boost set up. I want to do an LS swap eventually (hoping for 100k miles first) and I love the idea of a low boost induction set up. The cost isn't much more if you piece it together and the LS3 handles less than 10psi on stock internals easily. Those small parts add up quick on a build like this, when I LS swapped my 68 GTO I ended up 4k over budget. Kept running into the whole "might as well get the best and not worry about it later" scenario. Love the build, best of luck to you. Sent from my SAMSUNG -SM-G935A using Tapatalk

I think it would be a blast - but I think with that you go from reasonable conversion, to full on custom. The guys who've already completed there's could probably speak better towards available space, and getting enough air through there to keep it cool. With >500hp already available in NA form, I'm not sure if boost is really needed. But with these projects, 'need' is a pretty useless word. My worry would be the other drive line components. They seem to hold up fine on the crate LS's... but everything does have a limit.

There is no space for an inter-cooler. You can get all the power you need from an NA small block. Just buy a 427 or 454 LS motor instead of spending money on turbos and coolers 600 + HP is not hard to get in an NA motor

Not much progress... but felt the need to update anyway. They've got a dummy block in for fit-up, and should be putting in the real motor here in the next couple weeks.

Nice perspective! Looks like the firewall cut is very clean an symmetrical?

That is sooo cool. Going to be wicked fast and reliable. If not reliable, cheap to fix.:cheers:

Intake on and at the fab shop... it's getting serious! Against any sane judgement - we went with the Edelbrock intake... mostly because I love how it looks. Now it's time to finalize the intake/cooling routes and build the cage. I'll be in town to see the car next week, so hopefully will have a more in-depth update around the 1st.

OMG! So much for the stealth approach! :hilarious:

Looks amazing. what shop exactly is building it? About how much is the current estimate?

Thanks. The shop is Modern Aircooled in Houston. The estimate is roughly... a lot. I'm doing a lot more than your standard LS3 conversion, and my parts list is approaching $30k. This doesn't include the labor / custom fabrication.

Well, I made it out to the fab shop where my car is. It's still all just roughed in, as they were waiting for me to come in to discuss everything before doing too much. Still has the tow hook in from the day she died at MSR... Here you can see the cut out / access panel roughed in. The panel will be removable to make access easier. Everything will be sealed/weather stripped before completion. It doesn't intrude too much in to the cabin, and I'm putting in Recaro SPG's, so the space isn't an issue. (and I'm only 5'10...) Transmission Mounts... custom made since we're using the Cayman S transmission (Renegade only has mounts for the Boxster...) Engine mounts - went with the same system as Finger's build. A shim was added to help level the engine a bit. Nitro drag bike in the background for gratuitous HP porn. Next up: Weld in rear cage / bracing, finish off the metal work around the engine bay, intake routing, cooling, and exhaust.

Looks like you are running Corvette alum engine pedestals and then the Pfadt mounts with some adapters. Well thought out https://www.summitracing.com/parts/pre-1121000 I'm curious how that intake performs... haven't read anyone actually show a comparison of that vs. a stock LS3 intake.

We borrowed the idea from Finger's build here on the site. As we don't have the same clearance issues on the top end, we could add a little height. I'm interested in the gains from the intake as well. I don't have big hopes, but hopefully will get something out of it. I'm not sure I'll mess around getting a baseline dyno with the original intake/tune before putting on the Edelbrock... but we'll see. It depends if I'm broke by then. ;-)

Things are taking shape. Still just roughed in.

Making some progress with the rear cage...

This is the best thread on this forum.

You have another subscriber here! Hope to purchase a Cayman within the next couple weeks. Looks like I'll be starting with a low mileage engine, but the intent is to go this route when it gives up the ghost. Looking forward to your updates!

Thanks guys. Here's another shot of the cage from the inside. They're getting closer to being able to do the final welds, but still need to run the intake system, fit the window, and all the little bits & pieces.

Slow progress is still progress! A lot of finishing and final fitment going on, so while visual changes are small... it's not a small amount of work. Cage and metal work almost done / ready for final welding. Intakes should be fabricated in the next week or so. A header manufacturer is working on a product for the LS3 conversions for us, and we're due a test fitment piece around the end of next month. Spaces cut for intake routing: Cage (again) and some filler panels along the side to seal off the engine bay area from the passenger compartment: She's been on the hospital bed so long, she's getting dusty!

And... we do have intakes! The updates lag a little since I'm 5000 miles away from the car...

Hi Houston. Nice work! I'm doing a similar build, but with an Audi 4.2 liter. I'm thinking of using the same pump, but I'd like to see how you've mounted it and hooked it up. Do you have any photos?

I agree with Apex - nothing stupid about this. Mods are fun and very rarely logical. If you want to and can afford to, go for it!

I certainly hope that if Modern Aircooled acquires any other Caymans , for example wrecked ones, that they don't do one of these conversions just on a whim. I totally get an owner doing this to their own car, but I can't see doing this to a random car in hopes of selling it later, or to some historically significant car. Meanwhile it would be nice to see an update on the progress, I thought think you'd be close to the starting it up phase and then shortly thereafter driving it around!

Awesome build! And that intake is the real sh*t! Ever since I saw it a t SEMA I've wanted one!

Sounds like someone is worried about his baby? I don't know what Jordan may be planning, but I would be surprised to see him go down this road without a customer pushing for it. He's still very much a Porsche guy. When my car came in with a blown 3.4, he went through both upgrade routes with me (Built 3.8L vs. LS). Decision was mine to go with the LS. We'd probably be started and running by now, but the decision for that intake really set us back due to the amount of custom fabrication needed to accommodate it. All the panel work is done, cage is done, seat mounts done. They should be working on the exhaust this week or next . That should finish the fabrication work. Guard LSD should be at the shop... Accusump and the remaining mechanical goodies on their way... so hopefully by the end of this month it will be getting fired up. I certainly can't wait for some test drives

Thanks! Hopefully it turns out as good as it looks in my head right now.

Shift Cables in. Using similar set-up to how the cables are run through the stock firewall. Don't have to worry about stripping threads / crap sheet metal screws: Another shot at the firewall panel: