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3 car comparo 931/951/968, Where's the difference?
So I have a 931,951 and 968, with various mods so i can't exactly compare them stock vs stock, And I don't drive them very often (yet) or back to back FWIW. So this is just my $0.03 (hey inflation!)
Ill describe my observations, But im wondering what the majority of the differences are attributed too?
the 931, Intercooler added, k26-4, boost 11psi (vs 7 stock) some weight shavings (weighed at 2700 stock, removed about 200lbs.) D90s 7 205's/8" 225, 26.8 & 18mm sway bars, stock shocks/ original bushings. (strut mounts worn out!) and LSD trans,
968, mostly stock, except for gt3 Knock off seats (they fit snug!) and 19 Lobster claw wheels (275/30 rear).
So again I havent driven them back to back,
The 931 feels the most "raw" and basic, the steering is the heaviest, do get more feel, Steering feels a bit like a go-kart in its weight, especially with a 300mm Steering wheel, (definitely feels heavier than the 944 manual rack, especially, at low speed) Boost comes on a little sooner than a Stock 951, just a tad less laggy,( with the smaller Hotside and being right next to the head instead of 6ft of piping away.) Modified as it is It feels about as fast, maybe slightly more than a stock 951, but with a lighter, yet less refined feel (obviously with the older interior) When the boost comes on it builds pretty quick, with only 11psi for the moment, not as torquy as a 951 but when the boost comes on it pulls pretty good up top. Id say its Faster than the 968 in the mid-3/4 range. (or maybe it just feels faster, with more noise and vibration, and you can hear the turbo spool with a Cone filter) transmission is the audi unit not the Porsche G31. this particular trans is actually out of an 87 and it has a rebuilt LSD, also a short shift linkage and Bronze bushing shifter and Ball shift ****. so it has a much more machine like feel.
Id say the 931 is peppy, its the "miata" of the bunch. Definitely has a more "old school" vibe. and I like the narrow body. (Note: has old suspension, which is in the process of being completely rebuilt and upgraded and ill be adding a 19mm rear bar)
The 951 Has 996 seats in it, and a Aluminum Ball shift **** with Bronze bushings for a more precise feel. Again, it has the manual rack, Which in comparison to the 931, if I didnt tell you it was a manual rack, you might not know. steering Doesn't feel as quick as the 931, but easier to handle, more stable. This hasn't quite been properly tuned, so keeping the boost around 12psi (I think, with a Greddy EBC, which btw, is a pain to figure out!!) and this new EFR turbo spools really quick! coupled with the 3.5" exhaust, it blows through the RPM band too fast to watch the external boost gauge! (oh and the exhaust is pretty loud (Jones turbine muffler, with a smaller "race" muffler at the tip, and ATM wastegate so that is part of the "experience") When the turbo spools it sounds like a jet engine. (these new EFR turbos, make a night and day difference!) Really Pulls hard when the boost hits, its more of "hang on", then hit the brakes.
You can feel the heaver weight, and it feels like the car is more under sprung than the 931 slightly. But slightly more stable and comfortable.
I feel like 1st gear could be a little shorter to give a little more off the line torque (I have an S2 trans I'm going to try out),
It's kind of the Camaro/mustang/Viper of the bunch
The 968, does feel over all all better put together. the ride is slightly better, and It Does have power steering yet its fairly heavy, Not that much lighter than the 951/44 manual rack. One difference, is it feels more like you "aim" the car when turning. Feels the most steady, and most taught, which I like, and would like to add that to the 2 other cars. its has stock suspension, So I believe that means 26.8 front, but not sure on the rear bar. But it felt like it had the least amount of understeer. although the slowest steering of the 3. Im wondering how much might be due to the wheels and tires? They are lobster Claws with 275/30/19 and 255/35/19 (probably should go to 245s).
Engine wise totally stock except for air box mod and freeflow filter. It obviously has the most Tq down low, I don't even have to go to 1st gear unless coming to a full stop. Obviously no turbo lag, but on the other hand, no turbo BOOST! Definitely the most tractable engine. Best for a Daily driver/in town (Also I feel like Reverse is geared too high, always on the verge of stalling when backing out of a parking spot, and I kind of don't like that R is next to 1st, several times when down shifting to 1st, in a parking lot, I put it in R !!!)
The funny thing, is for some reason the Cockpit feels smaller in the 968, maybe its the Gt3 seats? and,or the airbag steering wheel? also the taller/filled/speaker door pockets? Also wonder how much the seats add to the "aiming of the car" feel since they are a snug fit.
Id say the 968 is the most "Porsche" like of the 3, (didn't get to drive it with stock wheels and seats, so I don't know how much that affected the over all feel), The price to performance ratio, id say is better than the 993, with comparable looks. Especially with 993's going for over $100k and 968's still $15-25k, Id definitely take the 68, plus the pop-up headlights are cool, (on the 944, not so much, im going to fixed projectors)
It's interesting how although they are kind of the same, they all feel noticeably different. I like them all, but for different purposes. The 931 is more the tinker toy, its cheap, and is the "what ever happens, happens!" car and has Zero arrogance/pomposity, it kind of the car id take when I don't feel like taking the motorcycle for a mtn drive, realizing It might not make it back, its the more adventurous drive of the 3. Your Wife/GF is going to complain
The 951 is the most exciting, but "could get into trouble fast" car, When I think of it, I hear Van Halen's "Panama" in my head. Hard to stay out of boost, Your Wife/GF is really going to Whine and nag!
If I had to Pick only one id go with the 968, for the "over all", I'd hop in it to go down the st or drive around the neighbor hood, wouldn't do that in the 951. The 931 id say is the most fun overall, including the tinkering/modding (as theres a lot more DIY/jerry-riggin, and experimentation) every drive is a box of chocolates! Infact I've spent most of the time driving it to test it out.
I've driven the 951 the least, even though i've invested the most in it. its kind of "go for a thrill ride", then "that's enough, don't want to break it".
SO: in the end Id like to cross over some of the attributes. Such as Id like the 931 to have road feel/steering more like the 968, and more power like the 951 (obviously).
So on the surface its
968
951
931,
But for me its really the other way around
931 "little buddy"
951 "Party hard"
968 "Cruisin"
thats all for now, if I think of anything else I'll update it.
"Die Transaxle Ara", as Porsche called it, evolved. Just as we did along with it.
The 931, but more realistically any 924 or 944, is a young mans car. Not ready for the power of manhood yet giddy and ready to chase a squirrel. Learn car control at an autocross or early DE fun.
The 951 has made some kills, earned the spot in the career path and can handle some thrust and bills. Rip the tires off and embarrass some high dollar cars. Adrenalin pump. How much do you want to spend?
968 is when you are done with the macho bravado and want to keep the polish and presence. I'm 57 and think I'm ready to join this club. YRMV.
928 is if you are ready to join the 968 club but need that extra 20% performance for 2x in price.
So the question still remains, what attributes the difference? Engine not withstanding.
on the 931 I just installed the 19mm rear sway (lowest setting) and all new poly front bushings, and firmer vw Fox strut mount, and front konis, (set on softest setting). Apparently the PO put on some stiffer front lowering springs, dont know the rate but estimate 200-225lbs. just took to for a short test drive, I didnt notice much of an improvement.
the 968 has the most "solid" feel, i was hoping to get near that with the improvements to the 931. They both have the same front sway bar. Felt like the 931 still had a little more roll in turns. BUT, I hadn't driven the 931 in a few months, after getting back I checked the tire pressure (front 205/50/16) it was 28psi.
Im wondering how much difference the wheel/tires sizes make? 19" vs 16" and 255/725 vs 225/205
So the question still remains, what attributes the difference? Engine not withstanding.
I think this can be broken down to two elements that are different... isolation and insulation.
Isolation development in major components like aluminum control arms, strut, suspension, engine, steering, exhaust mountings, down to minor components like wire loom (foam wrapped plug connections) and sub component to chassis attachments.
Insulation of the cabin thru application of heavy, heavy undercoating, fitted interior linings with separate soft and dense layers for attenuation, improved air seals and windshield design.
I think this can be broken down to two elements that are different... isolation and insulation.
Isolation development in major components like aluminum control arms, strut, suspension, engine, steering, exhaust mountings, down to minor components like wire loom (foam wrapped plug connections) and sub component to chassis attachments.
Insulation of the cabin thru application of heavy, heavy undercoating, fitted interior linings with separate soft and dense layers for attenuation, improved air seals and windshield design.
well its not so much the noise and vibration, its more the road feel. Maybe some of that is attributable to the weight? and or the weight of the wheels?'
I wonder also how much difference the slightly firmer rear torsion bars contribute. 137lbs in the 968 vs 126lbs in the 931. (also the rear shocks in the 931 are old, maybe even original? Sachs units ) another thing also, just looking at clarks-garage. looks like the stock 968 rear bar is 16mm instead of 18mm, so I would think the 931 would feel more stable than the 968.
too bad I can't fit the 19" lobsters on the 931 to compare
Apparently the PO put on some stiffer front lowering springs, dont know the rate but estimate 200-225lbs. I hadn't driven the 931 in a few months, after getting back I checked the tire pressure (front 205/50/16) it was 28psi.
What is the ground-to-fender height at each corner? Post a side profile of your car sitting on level ground. Suspect your car is running too much rake.
Your 968 has original 24.5 mm rear torsions? If so, those are [slightly] stiffer at ~149 lb/in.
Your 931 has new Koni sport struts and [original?] worn rear dampers. And that 28 psi was hot...depending on drive, probably 23-24 psi cold, and at least 10 lbs under-inflated. What was the pressure in the rear?
What is the ground-to-fender height at each corner? Post a side profile of your car sitting on level ground. Suspect your car is running too much rake.
Your 968 has original 24.5 mm rear torsions? If so, those are [slightly] stiffer at ~149 lb/in.
Your 931 has new Koni sport struts and [original?] worn rear dampers. And that 28 psi was hot...depending on drive, probably 23-24 psi cold, and at least 10 lbs under-inflated. What was the pressure in the rear?
I just did a little research, turns out the stock 968 rear T-bar is 25.5, so that would account for something.
No, I dont think the 28 psi was hot, as temps were about 50 outside, and i didnt drive very long, just about 20 min, in the neighborhood.
With the stock fuel system you can get that baby up to 15psi easy just watching your AFR on a good wideband until you trust it..
If it is a US car with lambda it can be real time AFR controlled with a microsquirt pretty easily including closed loop for excellent cruising efficiency (AFR around 15), and put your AFR wherever you want in boost (low 12s is great with an IC for power and safety, I aim for about 12.0 at medium boost up to about 18)..
Due to my measured fuel flow calculations I believe you can run 300HP on the stock fuel system and microsquirt control..
Add all sorts of sensors for full logging capability too!
Im running a custom fuel system (V8 distributor) on the same microsquirt control, the same turbo as you, and an intercooler..
I run it at 20psi usually and have ran it up to 25psi but it needs a bigger turbo for that..
LOT of potential man.. That engine is a TANK when it comes to cylinder pressure, just not so much for high RPM.. Torque monster..
Last edited by fasteddie313; 04-06-2022 at 12:46 PM.
there is a touch over 1.5 Bar of boost, 4th gear, at about 11.0 ARF solid..
She loves it!
I don’t check rennlist too often but I check 924board.org all the time, so find me if you wanna talk about really making that thing fast to where you can scare girls and 951s 😁
Oh yeah.. Stock internals.. (pretty darn easily)
Last edited by fasteddie313; 04-06-2022 at 12:45 PM.
there is a touch over 1.5 Bar of boost, 4th gear, at about 11.0 ARF solid..
She loves it!
I don’t check rennlist too often but I check 924board.org all the time, so find me if you wanna talk about really making that thing fast to where you can scare girls and 951s 😁
Oh yeah.. Stock internals.. (pretty darn easily)[/QUOTE]
Oh yeah, I figured I would have popped another by now too, but haven’t..
I popped the original HG, then replaced it with a new OEM HG, a DIY decking job, and ARP studs, and haven’t managed to blow it again yet..
Ive blown one turbo too, and boost pipes a bunch of times..
Im sure I’ll blow more stuff, and if it’s only another HG I’ll replace with an MLS or maybe even make a cutring HG..
Im going to just keep pushing, have a k27 compressor sitting here waiting to go in, and a 6.10 Turbine housing, and then I’ll dare it to blow the rods out of the block..
Then I’ll fix it again..
Keep my AFR under 12 on HIGH boost, and try to keep my RPMs under 6500, and stuff as much air in there as I can manage..
Thats the plan.. Long term goals..
Maybe I’ll stop when I max out the k27.. idk..
Love your permanent mount CIS tester!
Did you ever see the one I ran like that when I was still on my stock fuel system?
Was sooo cool! And so is yours!
Your FMIC looks very good!
Serious IC ready to handle some serious air!
03-17-2022 | 03:21 PM
3 car comparo 931/951/968, Where's the difference?
