Martin Anders

@Rick DeMan @BGB Motorsports and all - is there a 981 Spyder that has the 4.5L or 4.0 or 4.25 engine? If yes:

1) Do the stock Michelin Ps4s summer tires at 236/265 enable the power to be put on the pavement or does the spyder then need either 295 rear axle tires summer/street tires or 265 cup2s?
2) At which level of performance/torque (4.0l, 4.5l) do i absolutely need to upgrade clutch or even gearing parts?
3) the spyder standard suspension/chassis setup can handle the power? I have a B16 Pss10 from Bilstein, would that be enough?

sdillon

DeMan posted a video last February of a 4.5L in a Spyder:

Martin Anders

thanks - nice dyno - not much info on tires or changes to stock setup

burnergt4

I'm running the 4.5L in a GT4, so I can obviously only speak to my experience, but maybe it'll be helpful:

1) I've been using Pilot Super Sports for both street and track use—albeit in the GT4 stock sizes of 245 front / 295 rear—and they've been a really solid tire. Given that the PS4S is a newer compound, I'd imagine they'd have no issues even with the Spyder's slightly narrower track. I don't know what the 4.5L Spyder owners have done, but I'd venture to guess they've retained stock tire sizes. I recently threw on some 19” OZ Ultraleggera HLTs with a set of Pilot Sport A/S 3+ in 245 front / 285 rear for the winter/spring months and they feel great.

2) Definitely clutch with the 4.5L. This was something I'd asked about and it's a non-negotiable: you need something with high clamping force. I do not know if this applies to the 4.0/4.25L engines. Gearing-wise, several 4.5L owners have retained stock ratios and I haven't heard anything negative. I replaced the stock differential with a Guard LSD and I think these engines really benefit from a proper mechanical limited slip diff, especially under hard braking on track; @Luca Paindelli still has the stock diff on his car and might have some thoughts (he also has the stock gears, so if he ever gets the ratios replaced he'll be the person to ask in terms of differences between long vs. short gearing).

3) I forget the exact differences between the 981 GT4 / Spyder suspension setups, but—with the exception of a DSC Sport controller—I haven't touched the suspension on my GT4 and it handles the additional power with no issues. It really goes to show that the GT department made some great decisions with the chassis and suspension, so much so that you can run an additional 150+ HP through the driveline and it'll handle it beautifully.

Rick DeMan

We are on #28

Luca Paindelli

Yes, only did the engine on my wife's car; transaxle is still stock... But not for long: it has always been the plan to first do the engine and transaxle after; I think comes February/March I'll drop it off to Rick do do that, TPC toe links (to pair with the DSC Sport) and maybe exhaust to get the last 20 ponies... I think part of it was to spread out the cost and the fun, but also try out the car with the modified engine and the stock transmission.

The car now obviously accelerates quicker, no doubt about that, but shifting is the same. Gears were long and are still long; I tried Rick's test mule and the shifting is more engaging, more fun, more action with the stick in your hand... The diff honestly I haven't tracked the car yet so I can't tell you how the stock one performs under acceleration. I can tell you that under hard braking (even in a straight line and even with the lightweight flywheel) the rear end gets very vague and it feels like it's about to move around or if you add some steering input it would move in a way that it shouldn't. I've heard that a combination of DSC +TPC link (with changes in alignment) + more locking in the diff should take care of that.

I'm about 1hr away from Rick's shop so the decision of doing the work in sequence made sense for me; if I had to ship the car I probably would have done it all at the same time.

ajw45

Yes, many! I LOVE the 4.5l in the Spyder. I've driven a couple, recently put some miles on my friend's 4.5l Spyder w/ gears and diff and it was hilariously fun. For a car that is never going to see the track, I love the Spyder suspension and 19" wheel set-up. The car moves around more and I think it's just more engaging if not as ultimately capable as the GT4 pasm. Throw the big engine in there and is is one of the most fun cars ever.

1) No. Hell No. But I wouldn't change a thing. When testing the Spyder I pulled onto the highway, slow rolled into medium throttle in second, wheel spin, short shifted to third, wheel spin, pedal never made it to the floor and I never made it past 6k rpm. Awesome. 265, 295, sport, cup, you will be traction limited in 1 and 2, 3 depending on conditions and set-up. For a street car I like skinny tires and I think the suspension and steering feel better for it.
2) Clutch, just do it, gears, probably should do those too. I do think the diff is a nice add when you can spin the tires at will in the Spyder.
3) Kinda. I don't think anything is going to break but the 4.5l does turn it into a hot rod, more power than chassis, but I don't see that as a bad thing? I would totally leave the suspension stock and enjoy having the power to choose your angle at will. Maybe it would get frustrating after a couple sets of rear tires and maybe I'm a juvenile so ymmv but I'm a fan of stock.

Martin Anders

I am smiling when i read this - but i might be juvenile at heart as well Thanks for sharing!!

I now already have the B16 Pss10 Bilstein passive dampers as for the stock spyder suspension was having not so great dampers IMHO (based on gts/s but stiffer) and funny feeling at very high speeds + bad b-roads.
When the 4.0 X51 engine comes in in March i think i will first keep everything else (except headers etc + mentioned B16) stock and go from there. Might get some cup2 for occasional DE/trackday use - but less than 5-10% of car's miles per year. the 4.0 is no 4.5 -> i think with 10% shorter gears you could induce wheelspin at will as weel - will see if with the long gearing this works as well and report back

as to LSD/TBD => a nice guards or drexler real LSD would be ultimate => a wavetrac TBD could be a good compromise => but in all honesty - my driving skills need to be at a level where i would notice the diff vs. the standard 22% locking diff + electronic Torque Vectoring. As far as some mild drifting goes, the wavetrac should work as well (as it just doesnt work on braking like the true LSDs)

list for me - feedback/ideas/critique welcome:
- engine with street personality/tune and high torque as early as possible
- track day tire/rim set (265 or 295 rears to be decided)
- roll/sway bars + toe links (tbd if needed)
- LWF - from supplier that made these for Porsche for 911R optional single mass flywheel - to boost 2nd gear fun even further.
- Wavetrac (around 1500 USD) or true LSD (3000-4000 USD plus revisions every 2-4 years) - for alpine pass roads + mild drifting
- shorter gear set from Holinger oder Guards - Ring and Pinion - depending on need

Luca Paindelli

No ring and pinion: it's either the gears or you can run into trouble. There physically no room to put a ring gear of larger diameter so when you go with shorter final drive you're stuck with a ring of same diameter, smaller teeth and smaller pinion gear. This results in lesser surface for torque transfer and combined with the smaller teeth you could end up breaking the final drive, particularly when combining the higher torque of the engine with sticky tires. Don't do it! On a stock care you may get away with a shorter final, but on a DeMan car, do it Rick's way...

Martin Anders

thanks for the insight and explanation - rick's way is either 3,4,5 or 2 (mainshaft) and 3,4,5, correct? i will personally wait to see if i have the need for shorter gears for street usage and then decide - 4.0 motor with a bit less TQ (still 500/520NM vs 420 stock) at the crank.
once you go the journey of power, the rest of the car has to follow somewhat it seems or you end up with an overpowered 4.5l Spyder that is fun but not as fast maybe (and the owner likes it that way)

Luca Paindelli

I don't know if he lets custom pick which gears. But keeping 2nd stock is silly... Many have posted how the shifting feels even more awkward with a long 2nd and the rest of the gears closer together...

Supernutz

Screw the gear ratio, you guys need to try Rick 4.5L on PDK/GTS. that's the way to go, we got one

Brainofjjj

I know some of you get asked this a lot but if anyone wants to sell later in 2021 please let me know. I won't be a buyer until the Fall but if you're in line for another GT car arriving later next year and want to sell please PM me.
Thanks

burnergt4

DeMan currently has a fully built 4.5L for sale, FYI: https://demanmotorsport.com/product/...n-4-5l-gt4-ys/

oakmont

I am currently doing the 4.5L conversion on my GT4. Would love to join the facebook group. What is the name of it?

Looking forward to getting the car back next week!!