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Advice on swapping in a 3.0 liter 968

 
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Qik Nip  



Joined: 16 Jan 2015
Posts: 130
Location: Kentucky

PostPosted: Mon Dec 10, 2018 2:55 am    Post subject: Advice on swapping in a 3.0 liter 968 Reply with quote

As some here know, I run a '79 924 at Bonneville and other land speed racing venue. It has a fairly highly modified 2 liter naturally aspirated motor making about 210 horsepower. The car is a SCTA and ECTA record holder in the two liter Classic Production class. While I'll run it in 2019 as configured (in the hopes of bumping the Bonneville record to 155 MPH), the car has pretty well maxed out it's capabilities as configured.

To that end, I'm musing on the installation of a 3 liter motor and campaigning the car in a higher displacement class in 2020. I have read a number of posts here regarding swapping 2.5 Liter 944 engines in 924's, but haven't a clue as to how different/similar the 3.0 liter 968 power plant is to that engine. I do know it will require redesigning the engine mounts, dealing with the hydraulic clutch and of course adapting to the 968's ECM.
Any thoughts from those with (any) knowledge of the topic would be welcomed.
Rick
_________________
'79 NA 924 Land Speed Car
Bonneville G/CPRO record @ 149.825MPH
Arkansas Mile G/CPRO record @ 138.0 MPH
Great Lakes SCCA SM points champion '09,'10,'11


Last edited by Qik Nip on Sat Dec 29, 2018 9:32 am; edited 2 times in total
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morghen  



Joined: 21 Jan 2005
Posts: 8100
Location: Romania

PostPosted: Mon Dec 10, 2018 7:49 am    Post subject: Reply with quote

I guess you'll be modifying the 3L as well so it may make not so much difference but perhaps the 968 motor is a better start as it has around 240HP off the bat?
Compared to the S2 engine it has this vario-cam thing which you will probably not need in your application...but perhaps there is more to it that bumps the power from 210 to 240 S2 to 968.

What about the 2L you're using now?
What will happen to this motor?
Can you list the modifications that it has?
Some people may be interested in the knowledge of the mods or even the whole engine or parts of it if you'll part it.
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Qik Nip  



Joined: 16 Jan 2015
Posts: 130
Location: Kentucky

PostPosted: Tue Dec 11, 2018 1:19 am    Post subject: Reply with quote

morghen wrote:
I guess you'll be modifying the 3L as well so it may make not so much difference but perhaps the 968 motor is a better start as it has around 240HP off the bat?
Compared to the S2 engine it has this vario-cam thing which you will probably not need in your application...but perhaps there is more to it that bumps the power from 210 to 240 S2 to 968.

What about the 2L you're using now?
What will happen to this motor?
Can you list the modifications that it has?
Some people may be interested in the knowledge of the mods or even the whole engine or parts of it if you'll part it.


First I want to thank you for the 968 idea! I'll research that one a bit as well. If I proceeded with the displacement upgrade for the 2020 season, the engine would be an excellent power plant for an F Production road course car.
The motor is a Michael Mount produced piece and uses a lot of unique parts. It has a compression ratio of 13.7:1 and developed 208 HP @ 8200 RPM's on the engine dyno (without the custom exhaust header attached) and 152 pounds of torque. Presumably with the header installed, it gained as much as 10 additional HP. It has custom made J&E forged pistons, Cunningham rods, a custom ground cam with .563" lift and 293 degrees of duration. It has a significantly modified 924 Turbo head with 37.5 mm exhaust valves, 43mm intakes, Isky inner and 944 outer springs with lightweight 38.5 mm lifters.
It has two Weber DCO 50's on a custom intake, and a dry sump oil lubrication system. If I upgraded to a S2 or a 968 engine, I'd likely selling it complete as installed in the car since I suspect none of it's components would work on those engines.
Rick
_________________
'79 NA 924 Land Speed Car
Bonneville G/CPRO record @ 149.825MPH
Arkansas Mile G/CPRO record @ 138.0 MPH
Great Lakes SCCA SM points champion '09,'10,'11
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Fifty50Plus  



Joined: 28 Feb 2008
Posts: 1062
Location: Washington DC area

PostPosted: Tue Dec 11, 2018 2:04 am    Post subject: Reply with quote

The 924 was originally classed as an Improved Touring - B car some years back by SCCA. I looked into building an F production 924 car for SCCA but there are a bunch of rules restrictions called 'Limited Prep". Most of the cool things that you've done to your engine aren't allowed within the limited prep rules of SCCA. Based on our calculations within the limited prep rules we don't think we would have been able to get more that about 165 HP at the crank. F prod Miatas produce 175 at the rear wheels and have a lot less frontal area and weight benefits. (Miatas never started as Improved Touring cars thus no limited prep restrictions - and Mazda gives SCCA lots of money so they pretty much get anything approved that they want) Bottom line is that the other older Production cars wouldn't have been able to survive against the more modern cars that were originally classed as Improved Touring. Therefore SCCA restricted the amount of changes that could be done to the NA 924 engine. Same with the 944 engines.
Note that a key reason for building an F Production 924 is that it would then be eligible to compete in the Majors and qualify for the SCCA Runoffs. Improved Touring classes are considered Regional classes and aren't eligible for the Runoffs.
_________________
1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car
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Qik Nip  



Joined: 16 Jan 2015
Posts: 130
Location: Kentucky

PostPosted: Wed Dec 12, 2018 1:16 am    Post subject: Reply with quote

[quote="Fifty50Plus"]The 924 was originally classed as an Improved Touring - B car some years back by SCCA. I looked into building an F production 924 car for SCCA but there are a bunch of rules restrictions called 'Limited Prep". Most of the cool things that you've done to your engine aren't allowed within the limited prep rules of SCCA. quote]

Thanks for the thoughtful reply... I just read the 2018 SCCA Production rules (admittedly fairly quickly) and it would appear that the only modification that might be in question are the DCO 50 Webers. Of course the ITA classes are an entirely another matter where (for example) a dry sump system is illegal.
Rick
_________________
'79 NA 924 Land Speed Car
Bonneville G/CPRO record @ 149.825MPH
Arkansas Mile G/CPRO record @ 138.0 MPH
Great Lakes SCCA SM points champion '09,'10,'11
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Qik Nip  



Joined: 16 Jan 2015
Posts: 130
Location: Kentucky

PostPosted: Wed Dec 12, 2018 1:30 pm    Post subject: Reply with quote

Getting back to the point of this post, anyone here who can comment on the 924 driveline compatibility with the 3 liter block?. In a perfect world I'd love to put my clutch on the 968 flywheel and bolt the 924 bell housing to the back of a 968 block and move on. Looking at the pictures of that engine I've found on line, they do appear to have the same (or similar) bolt pattern on the rear, but I fear none of that will really work however. Any info appreciated.
Rick
P.S.: I realize the 3 liter mounts to the crossover versus the 924's body mounts and that the 968 clutch is Hydraulic, but that's about as far as I've gotten so far.
_________________
'79 NA 924 Land Speed Car
Bonneville G/CPRO record @ 149.825MPH
Arkansas Mile G/CPRO record @ 138.0 MPH
Great Lakes SCCA SM points champion '09,'10,'11
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Rasta Monsta  



Joined: 12 Jul 2006
Posts: 11377
Location: PacNW

PostPosted: Mon Dec 31, 2018 7:09 am    Post subject: Reply with quote

If you're committed to the concept, starting with a 924S tub would be exponentially easier.
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Qik Nip  



Joined: 16 Jan 2015
Posts: 130
Location: Kentucky

PostPosted: Mon Dec 31, 2018 8:45 am    Post subject: Reply with quote

Rasta Monsta wrote:
If you're committed to the concept, starting with a 924S tub would be exponentially easier.


After communicating with a very helpful Jon Mitchel of JMG Porsche Limited in the UK (who've done this transplant) it appears that the only sensible route is to build a 968 car if I elect to build a 3 liter car and stay with a Porsche. As I had worried, the cascade of changes gets totally out of hand on the 924-968 swap.
Rick
_________________
'79 NA 924 Land Speed Car
Bonneville G/CPRO record @ 149.825MPH
Arkansas Mile G/CPRO record @ 138.0 MPH
Great Lakes SCCA SM points champion '09,'10,'11
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CÚdric  



Joined: 27 Aug 2004
Posts: 1914
Location: Sweden

PostPosted: Mon Dec 31, 2018 8:59 am    Post subject: Reply with quote

I've seen it done on both 944s and 924Ss here in sweden, doesn't seem to be that much work if you start with a 2.5 car. Good luck anyway with whatever route you take on, I hope you will get another run with the 2.0!
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Qik Nip  



Joined: 16 Jan 2015
Posts: 130
Location: Kentucky

PostPosted: Fri Dec 27, 2019 2:08 am    Post subject: Long overdue Bonneville update Reply with quote

We indeed made the trip to the Salt in August but the rain gods had more to say than did the racers. After the rains fell the day before the event was to begin, we waited for three days while the salt attempted to dry, but in the end it was way too soft. The two cars immediately in front of me spun in the mush somewhere in the 2-3 mile section and while we managed to remain pointed in the right direction, the soft condition of the surface made accomplishing any real speed simply undoable. BTW the car after me also spun and then they closed the course. We loaded up and headed out on the 1,860 mile trip home!
_________________
'79 NA 924 Land Speed Car
Bonneville G/CPRO record @ 149.825MPH
Arkansas Mile G/CPRO record @ 138.0 MPH
Great Lakes SCCA SM points champion '09,'10,'11
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Fifty50Plus  



Joined: 28 Feb 2008
Posts: 1062
Location: Washington DC area

PostPosted: Fri Dec 27, 2019 8:32 am    Post subject: Reply with quote

Congrats on making the effort. For me a lot of the enjoyment is in the total effort from start to finish, not just the trophy or record. I've been running 12 and 24 hour enduros in SCCA for the past 25 years and have had my share of greatness and many tribulations. You and the folks that help you should be proud of what you have accomplished and remember to keep looking at the good parts and have fun.
_________________
1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car
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Qik Nip  



Joined: 16 Jan 2015
Posts: 130
Location: Kentucky

PostPosted: Mon Dec 30, 2019 6:22 am    Post subject: Reply with quote

Fifty50Plus wrote:
Congrats on making the effort. For me a lot of the enjoyment is in the total effort from start to finish, not just the trophy or record. I've been running 12 and 24 hour enduros in SCCA for the past 25 years and have had my share of greatness and many tribulations. You and the folks that help you should be proud of what you have accomplished and remember to keep looking at the good parts and have fun.


You're right. It's more about the attempt than the victory...but I do like the latter a bit more
_________________
'79 NA 924 Land Speed Car
Bonneville G/CPRO record @ 149.825MPH
Arkansas Mile G/CPRO record @ 138.0 MPH
Great Lakes SCCA SM points champion '09,'10,'11
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