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Super interesting. Curious what one should expect with a 997 GTS motor as the starting point. Warranty has already expired and this seems like a worthwhile upgrade on a high mileage daily GTS like mine
Super interesting. Curious what one should expect with a 997 GTS motor as the starting point. Warranty has already expired and this seems like a worthwhile upgrade on a high mileage daily GTS like mine
That is a perfect starting point for the 4.25L engine. You have the X51 kit already on the engine to make nice top end power.
Amazing work and results! Would this upgrade also count as a rerfresh for a tired 3.8 9A1 engine or would that be extra? I wonder how a 981 Boxster S would feel with this engine in it.
The only additional thing would be to refresh the heads. The entire bottom end would be replaced with new components.
Just got a ride in a 4.25l Spyder and the torque is insane!!! Wow. Completely different from my 4lx51 which was completely different again from a stock 3.8, it's hard to believe these are all the same engine at all. Low and mid-range torque is massive, so meaty, and when you roll into the throttle around 2500rpm the engine delivers a swell of torque without even going wot. From 3k-5k rpm where my engine is just waking up the 4.25l is already fully on and pushing you back into the seat hard. It feels like a totally different engine because there's power everywhere, all the time, and the torque delivery is super smooth through the whole rev range.
For reference, my 4lx51 is all top end with an almost stock like feel below 3k rpm that ramps up dramatically in the mid range and really screams from 6k-8k rpm. It's exciting but you need to rev it past 5k rpm to get to into it's sweet spot which isn't often reasonable on the street. The 4.25l is a hammer, it gives you torque on demand. Corner exit, hooning, commuting, whatever, this engine has a vastly wider and stronger power band. The 4lx51 feels fast because the torque builds with rpms and it's all noise and fury at the top end which I love but the 4.25l just IS fast. My 4lx51 with the lighter clutch/flywheel combo and race headers still feels like a more aggressive set-up from a sound and throttle response perspective over the 4.25l but then when you bury the pedal the 4.25l deliver so much torque it's like scrappy poo barking at a bear. I stepped back into my 4lx51 for the drive home and at street friendly rpms it honestly felt slow by comparison which I was not expecting. I have almost 9k miles on my 4lX51 and haven't driven a stock GT4 in, well, 9k miles, so I can't imagine what this would be like for someone coming from a stock engine.
Stepping back from it all, it's hard to believe these are all the same engine. The feel of these different engine builds are so different it's clear to me that Porsche gave the GT4 the engine they wanted to fit in their product line, not the best engine they could have given us for the price. Porsche de-tuning has made these maybe the most mod-friendly NA engines I've seen short of a sbc. Torque, horsepower, 4L, 4.25l, X51, GT3 intake, whatever you want there is more in this engine if you want it....
So, ajw45, DeMan is the lab, and you are the pusher, have I got that right? I am going on record as saying I would very much like a ride in the 4.25 liter car. Just sayin'. Thanks for the words and pix!
01-09-2019, 10:32 PM
I am going on record as saying I would very much like a ride in the 4.25 liter car. Just sayin'. Thanks for the words and pix!