944S 16V head with 944NA engine block

odie · 05-14-2003, 05:24 PM

I'm about 90% sure I'm gonna buy this car. It's a 1987 944S 16V. But the engine is knocking like crazy so I'm guessing main or rod bearings. I'm sure it's not the valve train, otherwise it would be siezed. The seller has only started it long enough for me to here all the noise and then shut it down. Replaceing the motor is a given.

After doing some research I've found that finding a good used 16V engine might take a while. But it seems that good running 944NA motors are somewhat plentiful.

Can a 944NA engine block be used with the 944S head? I realize that the 944NA engines have a littler lower compression than the 944S engine. But is this the only difference? Is everything that makes a 944S just a matter of the DOHC head and timing components, and external FI & ignition components which I could just swap over?

Do all 944 engines (na, 16V, turbo) share the same engine block, crank and rods? Are things like water pumps, alternators, AC compressors, PS pumps, motor mounts, etc all universal?

Another possibility is would a newer 1989+ 16V motor be a "bolt-in" swap for a 944S? Is there a 16V model other than the 87-88 944S?

Thanks for any info about this "hybrid" engine combination. I'm just coming over from the 914 world so I'm new at the 944.

ruechaos · ruechaos's Garage

I'm currently putting a '84NA engine into an '87 S body. Like you, I was considering swaping the head with a 16v one, but it whould be too much work for too little gain. That extra breathing dosen't really come into play until you get into the higher revs, so maybe you see a little bit wider torque band. Not worth it if you ask me.

If you are going to get an engine for the car, try to find a post 85.5. They changed a lot of little things here and there that could be a headache for you. You will also need a post 85.5NA DME and AFM, unless you do go for a "S" head.

I believe the rods on the turbo are different. The water pumps are universal, be sure that it's been updated, most have by now. The alternator on the post 85.5 cars maybe bigger to power all the new extras. Not sure about the AC compressors, I know they both use different amounts of freon, although.

There's the 944S2, but one of those engines are even harder to come by then an "S". Would be nice. 3.0L 16v....

Why not just fix the 944S engine? If it's cheaper to just fix it then to buy a new engine, it's a no brainer.

Good luck!

-Tony

odie · 05-14-2003, 06:48 PM

Well, fixing the 16V motor is prefered to swapping blocks. But until I pull the engine and open up the oil pan, I don't know. Maybe just replace the bearings and regrind the crank. But if the bearings were bad for a while, the block might have to be align-bored or might not even be saveable. At this point using an NA engine with all the 16V stuff makes much more sense.

eligunn · 05-15-2003, 05:23 AM

I guarantee that buying a good used engine is cheaper than rebuilding.

gt350mike · 05-15-2003, 06:34 AM

Quote:

Originally posted by eligunn
I guarantee that buying a good used engine is cheaper than rebuilding.

Buying a used motor is cheaper than rebuilding, but from a resale point of view, you would have to sell the car "miles unknown" because of the engine swap.

We bought a Camry that only had 44k miles with a bad motor, swapped it out for a motor that had less than 30k, but we had to sell the car miles unknown. That is the way law is written in AL because there is no way to document that the motor being replace has more OR less miles. The "Gray" area in this issue is factory replacement motors. Thats my .02!

SoCal Driver · SoCal Driver's Garage

Not only are there differances in the engines (I would use the N/A engine to replace the "S") there are differences in the DME and the wire harness that goes from the DME to the engine. Also some of the sensors are different too such as the idle bypass valve and the air flow sensor.

In other words you have to get more than an engine to swap between chassis.

odie · 05-15-2003, 09:45 AM

Basically, I'm thinking about rebuilding the "S" motor using an "NA" short block as the foundation.

May have to swap pistons or maybe the lower compression NA pistons have a lower crown height to avoid any valve clearance problems.

It's also quite possible that the 16V cams have less valve lift than the 8V cam because of the two extra valves. But then again the height of the valve seats above from the deck height are likely different.

I really need to get at some technical specs for both motors and start compareing. As well as comparing part numbers for the block, crank, rods, pistons.

If I can find a good dirt cheap NA motor, it would be worth getting it just to fit the parts together and spin the "hybrid" by hand. Put a little clay or playdough on the piston and look at the valve impressions.

If it works...great. If not...expensive experiment. If I slap it together without checking...really expensive experiment.

highboost951 · 05-15-2003, 10:54 AM

Just use the '87-'88 n/a short block except for the pistons and you'll be in business. If you locate an '88 you won't have a hard time selling the pistons as they're a mod for the earlier 944's. With an earlier block you won't have the self-tensioner, chances that the oil filler not bolting up and you'll have to drill and tap for the dme temp sensor.
Re-ring your S pistons and put new rod bearings in at least. Bolt on your S head and other components and stick it in.

robicurp@yahoo. · 05-15-2003, 12:16 PM

I'm not sure if an 8valve 2.5 l 944 engine block will work with a 16valve "S" head. I guess it would depend on the studs being the same.
One option I read about is using an "S2" engine. A guy bought a dead 944S, got the "S2" 3 liter engine with airbox, FI system, and computer from a salvage. It was basically a bolt-in swap.
Now he has 20 more HP plus the lower geared "S" transaxel.
I think he alos bought the bigger brakes from the "S2" as well.

tholyoak · 05-15-2003, 12:34 PM

The 944S head will not directly bolt to a NA or turbo block. The water passages don't line up. Not to say it can't be done, but it isn't bolt on . The headgaskets are obviously different between the S and the std 944/turbo as well (The S, S2 and 968 use a different gasket than the the 944 and 951)

Todd

odie · 05-15-2003, 12:42 PM

Can't the self tensioner be installed on the earlier blocks?

Tap and drill for the DME probably isn't as bad as it sounds if the block is the same casting. I'd just be finishing what the factory didn't.

Water passages in the head, that's a little different. Is it just a matter of pluging one passage and drilling another? The old 302 Boss Mustangs used Clevland heads on a Windsor block. Just plug old water hole and drill new one. Cut out hole in head gasket.

highboost951 · 05-15-2003, 02:01 PM

The 944S and reg. 944 use the same headgasket not to mention the 951. The blocks are the same until the '89 n/a came along at 2.7lt, displacement was gained by bore, it's basically a 3.0lt block w/ the 2.5lt crank. Anyways, yes the 944S head will bolt to the 2.5 block with a reg. headgasket and w/o any modifications to either the block or head for fitment.

overkill · 05-15-2003, 02:31 PM

Dude, just buy a 951. It will cost you alot less. Trust me. OH SHIZZ,... this isn't one of those "I'm thinking about turbo charging my NA,..." questions? OOPS! My bad bad

tholyoak · 05-15-2003, 03:01 PM

Highboost951 is obviously correct, I was thinking of the interchange between the 951 head and 944S2 and 968, when turbocharging those engines
Sorry for the misinformation

Todd

highboost951 · 05-15-2003, 03:27 PM

You're right overkill, it did look look like one of those by the title, we see those way too often.

overkill · 05-15-2003, 03:50 PM

HA HA HA, I know

odie · 05-15-2003, 08:47 PM

Well, I went and got the car tonight. Guess I'm committed. Or Maybe I should be committed for buying another project. I'll be closing on a house in the next 2 months and stting up shop. Until then I'll be poking and proding at the car to see what making all the noise and plan my attack.