tracknut

Hi All!

I have somewhat of a basic question - I was somewhat surprised to learn that the new 718 CS still has the old 3.8L engine from the 981 GT4 and not the new 4L - does anyone know why Porsche did this?

d00d

Not to be blunt, but yes, everyone does know.
You can read what people have already written about this in other threads.

Deepbluejh

The 3.8L is a tried and true motor that has been proven on the road and on the racetrack. Any potential quirks have already been ironed out. There are no surprises with it and parts are readily available. Basically, this is everything you want from a motor that will see regular track duty.

jmartpr

Plus was up gradable to the power levels of the new 4.0L and doesn't have to meet emission requirements.....Teams already knew well the engine.

Pcar81

Any opinions as to the reliability of the new 4.0 vs 3.8 for extensive track duty?

Maybe be too early to say?

Also how do the internals of the 3.8 compare to 4.0?
Titanium connecting rods, injectors, etc

jmartpr

Too early to tell with the new 9A2 N/A engine....the 9A1 3.8 is bulletproof. Race teams have run several seasons without a single issue, even using slicks on high-speed tracks which could be a problem for a car without a dry sump lubrication system.
I have personally put 24K miles on mine with lots of track time without a single issue...and mine does have several mods and I run slicks....really good engine in the reliability department.
The 9A2 engine in the 718 GT4 is brand new from scratch...maybe they have recycled a few parts from the old one...we wont know until cars are delivered. No Ti Con Rods..that's for the GT3 only. The injectors on the 9A2 are new and positioned in the center of the combustion chamber....so new heads also.

ajw45

There are additional features and complexity introduced in the new 4l that weren't needed to hit the ~420hp power target so there was no real reason for the race cars to move to the new engine. From what I can tell from the reviews so far, the biggest change is the new injection/ignition system which was driven primarily by emissions and features like cylinder deactivation. This in turn required moving the heads to a finger follower set-up like the 991.1 GT3. Some reviews seemed to indicate this change was for the extra 200 rpm redline but I'm skeptical - 8k rpm isn't meteoric and if they were really worried about the top end then the 991.2 GT3 solid lifter solution is simpler and likely less expensive/complex. Many already run the current 3.8 to 8k rpm with zero issues. This isn't a feature of the current turbo engines and while one presumes Porsche has done a ton of testing to make sure there isn't a repeat of the 991.1 GT3 engine issues, for the race teams there was no compelling reason to take that risk. I will be interested to see if this design makes a return to the 992 GT3 since I'm not aware of any other engines running a solid lifter arrangement like on the 991.2 GT3 that don't need periodic and regular valve/spacer adjustments.

So, instead of moving the race car over to the new engine, they kept the old engine and gave it a new intake manifold and cams. This is why I think that for people that already have a 981 and just want more power, modding the 981 makes more sense then moving to the 718. Now if you want pdk, carplay, aero, factory warranty, different spec, or want the full GT package on the Spyder, then the 718 is the way to go.

G-forceGT4

In the 718 GT4 thread a number of weeks back when the CS was released before the street car launch & a video posted with AP from Porsche discussing the 718 CS

His comments about why the 3.8L was retained in the 718 CS in summary:
very reliable & dependable race proven engine which teams know well and can easily obtain parts for their cars. Also Porsche bumped the power significantly with a few "tweaks" he mentions. A big factor that jmartpr noted is the emissions issue.
Porsche is also utilizing the 3.8L in the factory CS rally car they're testing for the big stage races

GrantG

Neither motor currently has Ti conrods (nor dry sump) - that is reserved so far for the higher revving 4.0 in the GT3/RS/Speedster. Porsche has said these features could potentially be added to the new 9A2 Evo 4.0L in the future, if desired (i.e. maybe in a future GT4 RS where higher revs would require one or both of these).

jmartpr

....Or they plan to use this engine as the base for the 992 GT3/RS

GrantG

I think that is highly unlikely, as the GT3/RS is tied to using the motor used in the race cars for homologation purposes in the case of the RS (which are not using the 9A2).

More likely to see the 4.0 9A2 Evo used as the basis of the next Turbo (where revs are not so high).

tracknut

This makes me feel better about the hard track driving I've been doing with my 981 GT4 haha!!

GrantG

In the center? Isn't that where the spark plug lives? Or is plug and injector side-by-side at the center of the valves?

jmartpr

Must be like that...I know....you can't have both on the same dead-center...must be they moved it closer to the center or right next to the spark plugs

jmartpr

To be honest...if I was looking for a dedicated race car for track days I would take a serious look at a 981 GT4 CS.....tires, brakes...add some gas and you are set to go without worrying about hours on the engine or transmission.