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I have some questions in regards to the motor:
1) am I missing much from not having the 718 CS intake?
2) the 718 CS intake seems to be the more popular choice than keeping the x51 intake bits (as they need to be programmed) - what is your opinion on that?
3) taking this well running motor to 4.25L or so would be a good choice or risky? if good choice what would be the way to go about it? or stay at 4.0L and do additional head porting?
4) am I missing any other bolt-ons or other mods for a road focused 981 Spyder?
5) using 93 Oct (US norm) gas - what do you believe could be a good HP result?
of course the same questions go out to the other forum members as well - especially the 4.0, 4.25 and 4.5L owners.
I apologize...we had a rather busy winter and i apparently missed this. I understand if you no longer need clarification on any of this. I did however want to chime in if need be.
1.) Relative to the X51 manifold, no but relative to everything else you can buy for an intake manifold for the car...yes. Under 5500 you aren't but over 5500 you're down almost 20rwhp.
2.) The X51 manifold is hard to fit in the car and while others don't like it or haven't found it to be an improvement, we have. I am on my 10th bored and stroked X51 kit. Rarely do customers forego the X51 swap.
3.) Going to 4.0L from 3.8L does not require an increase in bore; going to 4.2L from 4.0L does. If you're starting with a used 3.8L case we mandate that we plate them back to the original bore spec when they have anything more than 500 miles. We don't feel comfortable putting new rings in used bores so therefore it's definitely worth it to bore to 4.2L if you're already in there. If it was a virgin 3.8L, my answer would be entirely different.
4.) Once you install headers, a flash and the biggest intake you can, other than a LWFW, there's nothing else to do on a PDK car. on a manual car, gears can be done. that's it though.
5.) These engines are 12.5:1 from the dealer. The folks in California and other places where 93 isn't available are at a serious disadvantage. HOWEVER...i have had great luck with octane booster.
Finally, my answers are only in reference to the 4.2L. We do not offer a 4.5L for sale and will not ever.
Originally Posted by BGB Motorsports
i have a gentleman's agreement with the other shop in the country that does this conversion in the northeast to not sell the 4.0L bits and i am holding true to it.
This statement above is now no longer true. As of today we do not collaborate with anyone on these builds. They're done in house. I just finished a 4.3L X51 991.1 and the project started with a zero hour totally virgin engine purchased from Porsche in Germany. We did this as a concession for a customer that wanted the ultimate 911.1. There are no plans to go bigger whatsoever.
Precisely - he unluckily bought a pre-owned engine from some seller in germany that apparently had an previously undetected crack inside - obviously this comes out when you disassemble the engine like Rick did before boring.
He got a new crank case and i believe a 4.5L is on the way to him will report back from the German autobahn
I apologize...we had a rather busy winter and i apparently missed this. I understand if you no longer need clarification on any of this. I did however want to chime in if need be.
1.) Relative to the X51 manifold, no but relative to everything else you can buy for an intake manifold for the car...yes. Under 5500 you aren't but over 5500 you're down almost 20rwhp.
2.) The X51 manifold is hard to fit in the car and while others don't like it or haven't found it to be an improvement, we have. I am on my 10th bored and stroked X51 kit. Rarely do customers forego the X51 swap.
3.) Going to 4.0L from 3.8L does not require an increase in bore; going to 4.2L from 4.0L does. If you're starting with a used 3.8L case we mandate that we plate them back to the original bore spec when they have anything more than 500 miles. We don't feel comfortable putting new rings in used bores so therefore it's definitely worth it to bore to 4.2L if you're already in there. If it was a virgin 3.8L, my answer would be entirely different.
4.) Once you install headers, a flash and the biggest intake you can, other than a LWFW, there's nothing else to do on a PDK car. on a manual car, gears can be done. that's it though.
5.) These engines are 12.5:1 from the dealer. The folks in California and other places where 93 isn't available are at a serious disadvantage. HOWEVER...i have had great luck with octane booster.
Finally, my answers are only in reference to the 4.2L. We do not offer a 4.5L for sale and will not ever.
This statement above is now no longer true. As of today we do not collaborate with anyone on these builds. They're done in house. I just finished a 4.3L X51 991.1 and the project started with a zero hour totally virgin engine purchased from Porsche in Germany. We did this as a concession for a customer that wanted the ultimate 911.1. There are no plans to go bigger whatsoever.
thanks.
John
Thanks John, that answers very well all my questions
New one that piqued my curiosity - why no more than 4.2/4.25L with X51? 4.5l you would consider as not ideal for your application or not stable enough long term etc? would be interesting to get a "why" behind the decision - just to have different opinions. Have heard a similar one from Manthey racing in the past.
We are coming up on almost seven years from the first anniversary of this post. Lots of folks have asked why we haven't updated it and the biggest reason is just that we have had some staff changes, people going on to other industries all the while we have gotten busier and busier with the rest of the stuff in the shop and on the road. I did however want to chime in and bring to note that while it's been seven years, we haven't really revised our package substantially further than what we arrived on as a Stage III in 2018. I have built one 4.3L because i was able to start with a set of virgin case halves. As of today we build a 4.2L motor that starts life as a 3.8L and we install factory X51 cams, upgrade the heads to factory X51 spec as far as valvetrain and then we CNC port the heads. Folks are running whatever exhaust whose noise they prefer.
Since it's been almost seven years though i figured i would overlay something cool as a 5th and final run and that is from what will become the Grandfather of all factory built Porsche Caymans, the GT4RS. I think that at this point we can all agree that this will be the last Cayman that we all want if we lust for GT3 power in this car. When the car came out i began working on a package to make this engine run in a 2020 718 GT4 Clubsport and while that package will be tested later this summer, it further reiterated why i love our existing methodology. It would be great to have a GT3 engine in a Cayman but these four runs show that increasing displacement still gets you there for half the cost.
DYNO NOTES AS FOLLOWS:
RED: Bill's 4.3L X51 991 that runs the X51 intake manifold.
BLUE: Jake's 4.2L X51 981 that runs the 718 intake manifold.
GREEN: Customer's 4.5L 997.2.
ORANGE: Customer's 4.5L 718 GT4 Clubsport.
DARK BLUE: Bone stock GT4RS race car before they added restrictors and choked us down to 375/315.
IN CONCLUSION, without a displacement bump, we aren't getting even close to 450rwhp!
Hi John....thatnks for the update....what kind of exhaust the new 718 CS GT4RS run?
Bone stock. I haven't even driven the car without a restrictor and i can only imagine how awesome it is. I have spoken to Mitch and there's power to be gained still. The 992 GT3 Cup and the GT4RS overlay 100% to 7K RPM and then the Cup picks up another 50rwhp. over 7K to redline thanks to cams, race calibration and what's commonly known as real race car stuff.
Bone stock. I haven't even driven the car without a restrictor and i can only imagine how awesome it is. I have spoken to Mitch and there's power to be gained still. The 992 GT3 Cup and the GT4RS overlay 100% to 7K RPM and then the Cup picks up another 50rwhp. over 7K to redline thanks to cams, race calibration and what's commonly known as real race car stuff.
50 whp from Cup to Street car? That's a lot, we need to look into this!!!!!!
On the Clubsports I was referring if they run the same exhausts system as the street cars or do they have the cats back where the GPF used to be?
50 whp from Cup to Street car? That's a lot, we need to look into this!!!!!!
On the Clubsports I was referring if they run the same exhausts system as the street cars or do they have the cats back where the GPF used to be?
No no no...ABSOLUTELY NOT. Don't get me started until someone can explain to me why the Cup car has to be the hardest driving car in the paddock. If you want to make your passengers throw up and stall the thing 10 times, sure!
I am fairly confident that will will arrive on the street is the same as the race car EXCEPT without cats in the primaries, just like the 718 2020 MR and club/comp cars.
Since this thread is about modifications that can create horsepower on a Cayman GT4, i think it's appropriate to provide a link to our latest and greatest power producing item!
Hi John, I have written you several mails regarding my planed build (which corresponds to the red curve in your last shown diagram).
You may finally proceed with our communication
Hi John, I have written you several mails regarding my planed build (which corresponds to the red curve in your last shown diagram).
You may finally proceed with our communication
Your persistence is greatly appreciated! please forward one more time...i remember the conversation but cannot find the email. I know it's buried in there though. I apologize and thank you again for the nudge!
Since this thread is about modifications that can create horsepower on a Cayman GT4, i think it's appropriate to provide a link to our latest and greatest power producing item!
i don’t care about the performance but how does it sound?!?! I’ll take this GTfauxRS airbox over the GT4RS carbon airbox since it is the only option right now
No no no...ABSOLUTELY NOT. Don't get me started until someone can explain to me why the Cup car has to be the hardest driving car in the paddock. If you want to make your passengers throw up and stall the thing 10 times, sure!
I am fairly confident that will will arrive on the street is the same as the race car EXCEPT without cats in the primaries, just like the 718 2020 MR and club/comp cars.
Come on! There's got to be some secret sauce left that we can apply to the 4RS
08-09-2021, 08:35 PM
will report back from the German autobahn 
