16v 3.0 in 944 Turbo Surprises?

[Jotronic]

I'm at a cross roads regarding what kind of build I want to do from scratch. I am aware of how reading till my eyes are crossed can generate ideas of grandeur when it comes to motor swaps but I need some real world experienced input.

My conundrum is this. Stick with the 8v approach and push it to the higher end or pull the trigger on a 16v 3.0 build? I'm this close (imagine a small space) to pulling the trigger on the 3.0 16v turbo motor build option because I have a deal for a complete S2 motor freshly pulled for half the price of a turbo motor, less even. Seems like a no brainer, but with the experience I've gained from just adding aftermarket parts to my stock motor, and the headaches that can go with them, I know it won't be simply dropping my old motor and raising up a new one in it's place and turning the key to go.

I'm seeking a definitive list of things from my stock 2.5 motor that will or will not swap over to my 3.0 16 turbo motor. My car is a street car so I want to keep my power steering, my AC (upgraded to the Griffin unit), my Nissan alternator mod etc. I've been told these will bolt up.

I will get a new exhaust manifold (sfr) and intake manifold. I'll get a new harness from Bas and I have already a MaxxECU Race. My turbo will have to be bigger so while the stock turbo mount can swap over(?), I need a turbo bigger than my RaptorX.

What challenges can I expect during this swap? What swaps over, what doesn't?

Paging @chris white and @michaelmount123 as well as others with this type of experience.

Thanks in advance.

[Bergerac]

Have a look at my build thread Joe, that should give you some ideas about what's involved in a 16V build - https://carpokes.com/viewtopic.php?t=2764.

Most of the ancillaries fit, there's a few small changes around the oil pump/lower balance shaft housing that can catch you out, make sure you use the S2 parts.

Pistons will be the hard part, rods and bearings are pretty straight forward these days.

I would talk to Lance Hayward about an intake manifold while he still has castings available otherwise your going to pay a small fortune getting something fabricated.

Surely SFR can adjust your headers to to suit the S2 head, the cross over and turbo mount work,(with adjustment for your turbo of choice)

I would talk to Chris about one of his Xona Rotor turbos, the Raptor will definitely be too small.

[walfreyydo]

Just understand that the 3.0s weren't meant to be turbo charged from the factory and thus, cant hold much boost without bottom end work (weak rods and somewhat weak pistons). I would not push more than 6psi. 951 rods (forged) I believe are a direct swap and there are some aftermarket piston options out there (but would likely require sleeving as most arent compatible with alusil). That would likely apply whether turboing the 8V NA or the 3.0.

Youll also have the decision of whether to keep the 16v head and do a custom intake/exhaust manifold, or go with the 2.7L head (getting rare these days) which is the only 8V head compatible with the 3.0 blocks and use the 951 intake and exhaust manifolds. There is also a service which Lindsey Racing performs which can convert any 2.5L head to fit on a 3.0 block.

Your other option is to just swap a 951 engine using the factory hardware and plumbing, or keep the N/A 8v head and block and build the bottom end and swap over 951 ancillaries (you can probably find a lot of decent used parts for cheap) which should all bolt up to the 8V NA head.

Apart from the engine/head (if you opt to build it) almost nothing from the NA 8v engine will be used/swapped over in either case. You may also want to consider going standalone engine management to eliminate the need for the old 80s electronics (KLR, DME)

[Jotronic]

Just understand that the 3.0s weren't meant to be turbo charged from the factory and thus, cant hold much boost without bottom end work (weak rods and somewhat weak pistons). I would not push more than 6psi. 951 rods (forged) I believe are a direct swap and there are some aftermarket piston options out there (but would likely require sleeving as most arent compatible with alusil). That would likely apply whether turboing the 8V NA or the 3.0.

Youll also have the decision of whether to keep the 16v head and do a custom intake/exhaust manifold, or go with the 2.7L head (getting rare these days) which is the only 8V head compatible with the 3.0 blocks and use the 951 intake and exhaust manifolds. There is also a service which Lindsey Racing performs which can convert any 2.5L head to fit on a 3.0 block.

Your other option is to just swap a 951 engine using the factory hardware and plumbing, or keep the N/A 8v head and block and build the bottom end and swap over 951 ancillaries (you can probably find a lot of decent used parts for cheap) which should all bolt up to the 8V NA head.

Apart from the engine/head (if you opt to build it) almost nothing from the NA 8v engine will be used/swapped over in either case. You may also want to consider going standalone engine management to eliminate the need for the old 80s electronics (KLR, DME)

Thanks for your suggestions. I’m having a full rebuild done and on the 3.0 that would include proper rods and pistons with a lower CR to be a proper turbo motor. I’m staying away from a 2.7 head because if I’m going to the trouble of a 3.0 I want the advantage of the better breathing the 16v offers. I also already have MaxxxECU, an SFR bigger intercooler, bigger oil cooler, intake piping etc. My only concern are the ancillaries that make the swap complete for daily driving, ie coolant hoses, power steering pump, AC, alternator, etc.

[Jotronic]

Have a look at my build thread Joe, that should give you some ideas about what's involved in a 16V build - https://carpokes.com/viewtopic.php?t=2764.

Most of the ancillaries fit, there's a few small changes around the oil pump/lower balance shaft housing that can catch you out, make sure you use the S2 parts.

Pistons will be the hard part, rods and bearings are pretty straight forward these days.

I would talk to Lance Hayward about an intake manifold while he still has castings available otherwise your going to pay a small fortune getting something fabricated.

Surely SFR can adjust your headers to to suit the S2 head, the cross over and turbo mount work,(with adjustment for your turbo of choice)

I would talk to Chris about one of his Xona Rotor turbos, the Raptor will definitely be too small.

I appreciate your post as well as the documentation of your build. I read it before and it is fascinating, but also makes me think twice about going 16v. The Xona has been in my mind since Chris first started talking about them. Thank you.

[walfreyydo]

Thanks for your suggestions. I’m having a full rebuild done and on the 3.0 that would include proper rods and pistons with a lower CR to be a proper turbo motor. I’m staying away from a 2.7 head because if I’m going to the trouble of a 3.0 I want the advantage of the better breathing the 16v offers. I also already have MaxxxECU, an SFR bigger intercooler, bigger oil cooler, intake piping etc. My only concern are the ancillaries that make the swap complete for daily driving, ie coolant hoses, power steering pump, AC, alternator, etc.

Sounds like you are well on your way.

Most of the ancillaries will likely stay as is (I would think). The main challenge I think will be determining where you will mount the turbo and plumbing so that it does not get in the way of those. You can try under the intake manifold, like on the 951, but requires more exhaust plumbing, or try to fit it in the passenger side cavity where existing exhaust manifold is, which will hopefully be less complicated. Theres also the option of a remote turbo setup.

I have no direct experience with a 16V turbo setup, but hopefully others that do can chime in with the main challenges they faced when going this route.

[Jotronic]

Thanks for your suggestions. I’m having a full rebuild done and on the 3.0 that would include proper rods and pistons with a lower CR to be a proper turbo motor. I’m staying away from a 2.7 head because if I’m going to the trouble of a 3.0 I want the advantage of the better breathing the 16v offers. I also already have MaxxxECU, an SFR bigger intercooler, bigger oil cooler, intake piping etc. My only concern are the ancillaries that make the swap complete for daily driving, ie coolant hoses, power steering pump, AC, alternator, etc.

Sounds like you are well on your way.

Most of the ancillaries will likely stay as is (I would think). The main challenge I think will be determining where you will mount the turbo and plumbing so that it does not get in the way of those. You can try under the intake manifold, like on the 951, but requires more exhaust plumbing, or try to fit it in the passenger side cavity where existing exhaust manifold is, which will hopefully be less complicated. Theres also the option of a remote turbo setup.

I have no direct experience with a 16V turbo setup, but hopefully others that do can chime in with the main challenges they faced when going this route.

The turbo and plumbing location are the same on the 3.0 block as they are on a turbo block. Block is basically the same externally and a stock turbo mount bolts up. It just depends on the turbo that is going in because when you have a 3.0 motor, a bigger turbo gets the most out of the setup and a bigger turbo needs mount modifications, and that is where the intake issue comes in because the top of the turbo gets VERY close to the underside of the intake, which is why aftermarket is better. My Nissan alternator mod also helps create more room for the bigger turbo too.

Passenger side mounting is too tight although it has been done on at least one car where the motor was repositioned vertically like you'd see on an SR20 Nissan motor. That and a remote mount system would be too much fabrication work for an unknown outcome. I don't want to reinvent the wheel with this.

[Bergerac]

I hate to say this but you've done all the hard work on your 8V motor, why not see it through and run some more boost. A bit of head work, maybe a cam and some stronger rods/pistons and you should get some more power without the 16V dramas. Theres probably another undocumented issue I've had to solve for each one in my build thread, it's a long hard road.

[Jotronic]

I hate to say this but you've done all the hard work on your 8V motor, why not see it through and run some more boost. A bit of head work, maybe a cam and some stronger rods/pistons and you should get some more power without the 16V dramas. Theres probably another undocumented issue I've had to solve for each one in my build thread, it's a long hard road.

Can you give me examples of these problems? Your post is very valuable to me and is what I was hoping to hear.

Everything that bolts to my current motor is new. All coolant hoses. All sensors. Alternator. AC (Griffin upgrade). Wizard radiator, LR 3x oil cooler, SFR stage 1.5 intercooler, IC pipes, intake, I also have 996tt brakes, all new suspension rubber from Elephant Racing, Intrax coil overs. I have the 01 E swap kit coming and am having a 01E rebuilt. Will do a new clutch and PP. Torque tube will be rebuilt with bigger new bearings.

If you could shed some light on the unlisted problems it would be a MASSIVE help.

[Bergerac]

I guess to summarize;

- Intake manifold clashed with coolant elbow so I had to make custom coolant lines,
- Turbo coolant line/temp switch clashed with intake due to bigger turbo so it had to be modified
- Turbo coolant pump clashed with turbo intake so had to be moved and now clashes with my strut brace
- Turbo inlet clashed with Nissan alternator, no fix for that, the silicone intake hose pushes up against the terminal. Will need to investigate a different alternator at some point.
- Heat shields around the turbo had to be modified to fit
- AOS outlet clashed with inlet manifold, and hard vacuum lines dont fit. Not a big issue as Ive deleted most of the stock vacuum lines but you will need to go DBW to delete the ICV.
- I ended up with a turbo oil pump, this is not compatible with the 16V timing belt arrangement, and there was another issue with the lower balance shaft end cap/power steering mount which I cant exactly remember but I had to swap it off my S2 motor.
- Depending on your intake manifold/throttle body choice you will need custom intercooler pipes.
- Issues getting the exhaust manifolds/crossover modified to work together ( trying to weld old dirty heat cycled SS)
- Custom harness to combine the turbo/16V differences (cam sensor, 2x knock sensors, single speed/ref sensor, high low injectors/ballast, . May as well go fully sequential while you're at it)
- Custom pistons which are expensive ($1300+shipping/taxes from Mahle)
- Ended up being cheaper getting custom valves made than buying originals from Porsche, and very hard to get heavier springs if you want to go that way, Cat Cams is basically the only option.
- No room for turbo filter/airbox so custom piping to filter in bumper.
- Modifying the upper balance shaft housing for turbo oil feel.
- Modifying sump for turbo oil return of not already drilled.
- Custom dipstick tube to clear turbo/manifold.
- Custom fuel lines FPR/Damper to suit manifold/fuel rail.

Im sure there is others that Im choosing to forget plus multiple times I've wanted to drop a lit match down the fuel filler and walk away. Youve got to remember that even though you're getting a deal on the motor ,there's no guarantee you wont need to get it sleeved or nikasealed, there's no issues with the cams or the head like you've already experienced ,is the crank in spec? I started out with the plan to rebuilt my S2 engine and ended up buying a brand new 968 block and head because there was simply no one close to me that I could trust to work on my block and it ended being cheaper than shipping overseas to get the work done.