3.6 Engine Rebuild Parts Recommendations

yahh · 06-21-2018, 06:04 AM

My 964 3.6 is supposed to be arriving this week for my SC backdate project and I am looking for some guidance. I will be tearing the motor down completely for a rebuild. The heads have already been machined so I don't need to have that done. This will be a street car with some track days thrown in, but in no way am I looking for a 3.8 RSR race car build or a 40k engine build. This car will be daily driven when the weather permits which is about 10k miles a year so reliability is a must.

Plan is
- Stock bottom end rebuild and re-ring pistons - have everything checked/machined where necessary
- Dougherty DC21 Cam w/ matching valve springs and titanium retainers and rocker arm o-rings (John's recommendation was ARP rod bolts only if shifting over 7k so I probably won't use them.)
- VEMS Stand Alone w/ custom dyno tune

I would like to keep heat so the exhaust setup will be 993 heat exchangers to a custom muffler setup. Will that restrict the motor much?

Do the head-studs need to be replaced on these like the 3.0 engines? I know people had recommended upgrading to the 3.6 studs so I assume they don't break. I used Supertec on my last motor.

What else do you guys recommend that will work with that setup? What can I do to help the cams breathe better? PMO EFI TB's? What's the gain from going ITB's? My goal is 100 hp more than my 3.0 put down which would be about 280hp, but more is always better as long as its reliable.

Thanks!

faverymi · 06-21-2018, 06:19 AM

3.8 rsr not very fun on the street.

Very fun at WOT

I recommend you read more. Plenty of threads. And of course plenty of opinions.

I personally really like the 3.8 itb backdate that flying hawaiian sold on bring a trailer. And streetable

JonT · 06-21-2018, 07:23 AM

I'm going through this exact process now with my mechanic on a 964 3.6 build. He's wrapping it up soon hopefully.

I would do new headstuds, precautionary while its apart. Same for ARP rod bolts. Not too expensive and you cant reuse factory anyway.

I went with new Webcams 993 supersport cams vs. Dougherty DC21 based on recommendation but others have praised Dougherty camwork as well so probably a wash there.

I have a Steve Wong chip that has been custom tuned with lightweight flywheel. Also have same exhaust 993 cat with tips (no muffler). Not much of a restriction on motor if any.

You should end up with around 300hp at crank with that setup. Mine dynoed at that level.

Good luck you'll love the results.

3rd_gear_Ted · 06-21-2018, 07:52 AM

One other aspect; SC backdate will limit your options for oil coolers to inner front fender mounting.
Both fenders will need max size oil coolers and -16 oil lines @ 300 HP
BTW, a 964 nose allows a 72 row front oil cooler with room behind it for proper air flow.
IROC bumpers don't have the space, been there, done that

yahh · 06-21-2018, 09:44 AM

Quote:

Originally Posted by faverymi

3.8 rsr not very fun on the street.

Very fun at WOT

I recommend you read more. Plenty of threads. And of course plenty of opinions.

I personally really like the 3.8 itb backdate that flying hawaiian sold on bring a trailer. And streetable

I've spent quite a bit of time researching, there is just A LOT of info out there and much of it clashes with one another. I'm looking for people who have done similar build and have experience with them.

faverymi · 06-21-2018, 09:58 AM

Quote:

Originally Posted by yahh

I've spent quite a bit of time researching, there is just A LOT of info out there and much of it clashes with one another. I'm looking for people who have done similar build and have experience with them.

I own 2 different 3.8s based on a 964 and other 993

One for the track one for street

One is on a SC chassis one in a 90s chassis

Call me if you want to chat lots of approaches.

I've been to spanking machine a few times. Happy to share my experience so you don't have to.
Six one seven five nine nine nine six three four

smokintr6 · 06-21-2018, 10:38 AM

For what it's worth, a stock 964 3.6 is going to be potent in a 911 SC chassis, without further mods. If you find yourself asking: do I want to spend several thousand dollars for a 20hp bump, the answer is probably "no". I've had a 360hp ITB engine in one of these chassis before, and it was LESS fun on the road than my current bone stock 964. My advice would be not to do anything to disturb low end torque delivery. Personally I also like the way the plastic plenum sounds better than the ITBs at partial throttle (around town). I would do the head studs, and probably would lean Supertec based on others' reviews

This is what the stocker runs like being flogged. Only mods are B&B headers, a flowmaster muffler, ARP rod bolts, ARP head studs:

https://www.youtube.com/watch?v=ezbE24oswZI

flyn-hawn · flyn-hawn's Garage

I did a 3.8 in the blue rsr inspired car, went for torque and mid range over higher hp at the top end. The car is very driveable on the street and does not stop pulling until 6800rpm. Want to do another but with GT3 plenum for more torque, ITB is sexy though... Either way build is 50K +/- going with nice parts and pretty looks.

smokintr6 · 06-22-2018, 04:40 AM

Quote:

Originally Posted by flyn-hawn

I did a 3.8 in the blue rsr inspired car, went for torque and mid range over higher hp at the top end. The car is very driveable on the street and does not stop pulling until 6800rpm. Want to do another but with GT3 plenum for more torque, ITB is sexy though... Either way build is 50K +/- going with nice parts and pretty looks.

That's kind of the conundrum that I have with the 3.8 vs cost.... I wouldn't mind having a little more torque and power (who would?).. But 3.8 p/c s are $6k ish for LN parts? and then the machine costs to the case? Seems like it becomes an $8k project minimum by the time you install and change the tune, and what is the HP return for dollar on the upgrade?

GaryR · GaryR's Garage

Go with cams and a custom dyno tune, I would do new ARP studs/con rod bolts also. If you are on the east coast John Behe can do the chip tune (near DC), otherwise find "the guy" in your area. Much better than a Wong chip IMO, very specific for your car and backed up with a dyno sheet and A/F graph. He may also suggest a different injector, etc. to keep the A/F in a better range (or may not!). Add headers (with heat if you need it) and a good flowing exhaust (before the tune of course), enjoy!

KTL · 06-22-2018, 06:41 AM

Just to add what the other guys said, the head studs are a very smart thing to do on the 964 3.6 if you're tearing it down because ALL 24 of them are the notorious smooth/coated dilavar. The 993 engines have all 24 studs in steel and then the 993 twin turbo engines have the special fully threaded dilavar studs. Those fully threaded studs appear to be the only dilavar stud that is any good.

Bill Verburg · Bill Verburg's Garage

I'd stick w/ 3.6 and maybe RS(hyd) or SS(mech.) cams, you'll be very happy for street use.

I've used 2 different 3.6 and a 3.8RS in mine the happiest combo is 3.6 993+ 993RS cams + Wong chip, next was a bone stock '93 964(plastic intake) unhappiest was the 3.8RS which was quickly t/p'ed into my track car. The 3.8 + 915 isn't the best way to go for street use especially w/ an shorter geared SC and earlier.

the 915 issue is related to lower gear torque loads, where you are puting 800 +lb-ft through the output shaft in 1st and 3300 + lb-ft through the cwp, things tend to move around a bit. You'll want a girdle and 930 side plate to stabilize it