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Thanks for your input. Did you see a noticeable torque increase as well?
Short answer, no. Peak torque was up maybe 10 ft/lbs, it's not like dropping in V8 or a turbo.... or a turbo v8. Running the numbers, .2L is only like ~5% so call it worth about +16ft/lbs PEAK if it was a linear rate of torque output to displacement and ignoring the contribution of added compression. From a power to weight perspective that's like the difference of having a passenger or not, subtle, my butt dyno probably won't notice.
But that's just a the static peak dyno glory number. The long answer is that it's the combination of the added displacement AND the X51 that makes a good torque story. 1k-3k rpm I cant tell the difference from stock + headers, probably feel the ltw flywheel more than anything else. 3k-5k rpm the torque delivery definitely feels smoother than before (different intake helps smooth out some of the peaks and valleys in the torque curve), passing on the highway is easier so I'm less likely to drop a gear, but it is subtle until around 4k rpm the engine starts to wake up and the juice over the 3.8 starts to become noticeable. 5k-8k rpm is like a whole different engine, the urgency and pull all the way to redline is ridiculous. I don't have the dyno handy but while peak torque is only like 10ft/lbs more it hits at ~7500 rpm vs ~5500rpm (~5500rpm post headers on my car, Porsche GT4 spec is 309 ft/lbs @ 4750rpm peak). @ 7500rpm where the 3.8 is close to redline and torque has dropped off to nothing burger the 4L X51 is at it's peak making over 60ft/lbs more torque.
The downside of all this is that 6k-8k rpm goes by too fast in first gear to enjoy it and by the top of second you need to be scanning for cops. It really needs a track or a different country to enjoy it all.
Short answer, no. Peak torque was up maybe 10 ft/lbs, it's not like dropping in V8 or a turbo.... or a turbo v8. Running the numbers, .2L is only like ~5% so call it worth about +16ft/lbs PEAK if it was a linear rate of torque output to displacement and ignoring the contribution of added compression. From a power to weight perspective that's like the difference of having a passenger or not, subtle, my butt dyno probably won't notice.
But that's just a the static peak dyno glory number. The long answer is that it's the combination of the added displacement AND the X51 that makes a good torque story. 1k-3k rpm I cant tell the difference from stock + headers, probably feel the ltw flywheel more than anything else. 3k-5k rpm the torque delivery definitely feels smoother than before (different intake helps smooth out some of the peaks and valleys in the torque curve), passing on the highway is easier so I'm less likely to drop a gear, but it is subtle until around 4k rpm the engine starts to wake up and the juice over the 3.8 starts to become noticeable. 5k-8k rpm is like a whole different engine, the urgency and pull all the way to redline is ridiculous. I don't have the dyno handy but while peak torque is only like 10ft/lbs more it hits at ~7500 rpm vs ~5500rpm (~5500rpm post headers on my car, Porsche GT4 spec is 309 ft/lbs @ 4750rpm peak). @ 7500rpm where the 3.8 is close to redline and torque has dropped off to nothing burger the 4L X51 is at it's peak making over 60ft/lbs more torque.
The downside of all this is that 6k-8k rpm goes by too fast in first gear to enjoy it and by the top of second you need to be scanning for cops. It really needs a track or a different country to enjoy it all.
This is actually a rather awesome opinion and one that i probably could not have written better myself. I agree with everything he says. It's my opinion that the X51 manifold and runners are so big that you actually lose a tiny bit of torque but what you give up, you get back in a massive amount of horsepower. The addition of the 4.0L bits generates a massive increase in torque and actually some additional power. I was always taught that small intake runners down low make good torque and big runners up top make big horsepower and that's why the X51 is a great dual purpose manifold and that's why the torque number on a Stage I GT4 or clubsport is pretty decent. those small intake bits make good torque. We all have the same feedback too about the X51 - over 5K RPM, it's as if it morphs into a 4 stroke dirt bike motor the way it starts ramping up and pulling harder and harder all the way to redline. The final comment is the best though - you really can't enjoy this thing on the street because it pulls so hard to the redline you're going 100 before you even know it. I got on the highway last week on a road test and hit triple digits before i could even tell what was going on. You have to be careful about that stuff.
Glad to hear you're enjoying your car buddy! Thanks for chiming in. I can say these things til i'm blue in the face but i've always preferred customer feedback because then it's not a sales guy selling - it's two folks talking!
Originally Posted by Buteo
Whats the ball park price here? Asking for a friend that already has a Cobb, IPD plenum/gt3tb, Dundon header.
Everything is up on the web site but we should talk on the phone because you have mods already that can be re-used. Your manifolds, your Accessport, your throttle body, etc. If you want Wray or I will be more than happy to walk you through it. Just send me an email please or call us.
Originally Posted by pcolony
I too have a "friend" that's curious about the price.
Hmmmm...do i smell a BGB Stage III 4.0L X51 Group Buy?!?!?
I'll send this to my friend who is debating whether to cancel private school for his kids for 1 year or to make his car faster, I think the answer is clear.
Group Buy! John...that's not fare! Now you are playing with my mind.
Does the group buy includes travel and hotel?????
Seriously.....I'm on the list for (if it ever happens) for the next GT4...it all comes down to what PAG does to that car.
But if I decide to keep the current one this is definetly going to happen...besides that little project on the transmission we e-mail about.
I'll send this to my friend who is debating whether to cancel private school for his kids for 1 year or to make his car faster, I think the answer is clear.
Is your fiend following your footsteps and getting rid of his kid?????
Group Buy! John...that's not fare! Now you are playing with my mind.
Does the group buy includes travel and hotel?????
My 'friend' suggested we all do the group buy at the same time, rent out a villa by the beach for a month, and relive our glory days when we were in a frat.
Originally Posted by jmartpr
Is your fiend following your footsteps and getting rid of his kid?????
How does the sound change after 5k rpm? Do you have a clip comparing before and after? I love the change in tone around 5k but I wish it got angrier and angrier all the way to redline. Is X51 the solution?
Glad to hear you're enjoying your car buddy! Thanks for chiming in. I can say these things til i'm blue in the face but i've always preferred customer feedback because then it's not a sales guy selling - it's two folks talking!
Absolutely and thanks for investing all the development time in the tuning and installation process to make this a real thing for 981 owners! It's weird because I know there are other 4L X51 owners out there, enthusiasts I assume since this isn't a cheap mod, but none of them seem to be on RL. Selfishly, I just want to see more engine builds and fast GT4s on RL in defiance of Porsche's constant detuning to keep the 911 at the top of the food chain
Thanks Cosimo! Only if i can then visit Italy to inspect it all!
The most recent 4.0L builds have all been X51 4.0L builds and the top end power is unbelievable on the race track. We had to put a roll cage in Colonel Mustard because he was exceeding 175mph at Daytona. Sorry for the poor sound quality. https://www.youtube.com/watch?v=8h03e79kX-g&t=19s
We are ready when you are Jose. I think that you would like the additional top end power!
We have built several west coast cars and i have customers up and down the left coast. With the more expensive labor rates and taxes out there i bet we could undercut anyone and even still have room for cross country shipment!
The Power Kit is advertised as an additional 30 mechanical horsepower and while we have dyno proven that repeadtedly, I think the gains in the top of the rev range are where it's extremely noticeable because the better breathing X51 parts create a near perfect power and torque curve. The X51 Power kit bits really create horsepower and not much additional torque if any; it's advertised with 30 additional and not 1 single lb/ft and i have seen it myself on the dyno. The gains are noticeable above 5K RPM - my project GT4 that was built with all of the same bits as this car produced nearly an additional 80 rwhp over a bone stock GT4 at 6700 RPM where the stock GT4 runs out of air. I had my cylinder heads ported additionally so i think this car will be within 10 hp of my car's making 407 - 415 depending on fuel types and weather conditions.
I have attached the baseline dyno run below that produced about 360rwhp and for comparison purposes, below is a graph of a stock GT4 relative to the dyno analysis from yesterday.
Stock GT4 Dyno Comparison vs. BGB Stage I with Cobb Pro Tune, BMC Filters, IPD Plenum, 82mm Throttle Body & Cargraphic Stainless Steel Race manifolds.
My set up (stage1) with custom tune made by John.... The car is a totally different beast :-)
My 'friend' suggested we all do the group buy at the same time, rent out a villa by the beach for a month, and relive our glory days when we were in a frat.
He's contemplating it.
SPRING BREAK 1995! I mean, SPRING BREAK 2018!!! I was never in a frat in school so maybe this would satisfy that curiosity. Maybe if it bleeds over into Bike Week we could get cuts & colors made. "we're more of a club than a gang really!?"
For those folks that wanted quotes, i sent you PMs with my contact information. Please email myself or Wray at the email address on the web site so that we could have quotes for you before the weekend so that during the weekend, you can begin to torture yourselves!
02-15-2018, 04:46 PM
I mean, SPRING BREAK 2018!!! 
