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How do 3.9-4.25 builds compare to 991s

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Old 02-06-2017 | 10:24 PM
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Default How do 3.9-4.25 builds compare to 991s

Haven't seen very much data in terms of dyno sheets or real world accounts so was curious to see how these cars with motor builds stack up against 991 GT3 and RS. Obviously it's an investment to do a motor build so would like to see real world data/impressions.
Old 02-06-2017 | 10:29 PM
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Its about bout time for a thread like this. I have been on the fence about what direction to go for a year already. Did not get to far last year finding a core to have a bike done and ended up buying another boat...

Hopefully some people can chime in with real world experience.


Originally Posted by bmwtye
Haven't seen very much data in terms of dyno sheets or real world accounts so was curious to see how these cars with motor builds stack up against 991 GT3 and RS. Obviously it's an investment to do a motor build so would like to see real world data/impressions.
Old 02-07-2017 | 12:15 AM
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Hoping Ranger responds and whoever bought his car.
Old 02-07-2017 | 12:39 AM
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Ranger , Ara if he's still here or bbi as they have done 2 4.25s, sharky, leh keen and frog 4.0 and I know there are several others with 3.9s
Old 02-07-2017 | 12:45 AM
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So here's the deal, I've only ridden in the 4.25 L that BBI has done. That motor is EXPLOSIVE. Literally. I've driven and ridden in plenty of fast cars, but that thing scared the **** out of me. And is probably the reason I haven't done one. It would get me in too much trouble.

Ara's has been built I think coming on 2 years??, and running strong. They just finished another one based on a .2RS that will be delivered to the customer soon.

Compared to a 991RS it felt more violent, but I'm sure the 991 is faster on track, probably in a straight line. Why? PDK.

These are big $ builds but if you want ~ 100 more WHP.....
Old 02-07-2017 | 12:55 AM
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PJ is doing a 4.2 build. So we will find out shortly
Old 02-07-2017 | 03:06 AM
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My stock 3.8 with 4.0 RS LWFW feels plenty powerful above 4k RPM to me Can't even imagine a 4.2L... Must be monstrous!
Old 02-07-2017 | 12:26 PM
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I've driven a 991GT3 on my home track. While the gearbox is seamless with lightning fast shifts that any blue haired grandmother could click off, overall I didn't find the car all that fast. It is numbingly simple to drive (almost boring) but all nanies must be turned off for good lap times as I found them pretty intrusive. On NT01s in my 996 with a built 3.8 I was an easy 4 seconds per lap faster on a 2 min course. A built 7GT3 will be faster in my opinion than a 991 also.
Old 02-07-2017 | 12:30 PM
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If anyone is in/around the NYC area, I have a SharkWerks 3.9 and am always happy to find a time to show off how amazing Alex and team's work is. I will never sell this car. I've driven a 991 GT3 and love it. This car is completely different. Depends on what you want.
Old 02-07-2017 | 10:48 PM
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Have zero seat time in a 991 so cannot comment on differences between 991 and a 997 GT3 with build. Currently have a .2 GT3 with 4.0 engine package. It definitely transforms and already very capable car. Biggest improvement to me is low RPM grunt, more torque for sure. Having more torque and power in a GT3 flat 6 NA package is the deal.

It's also loud as hell which only improves the experience, GMG headers, side pipe delete and most likely burnt out cats. Wife has refused to ever get in it, that alone might be worth the price of admission
Old 02-07-2017 | 10:54 PM
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Just to clarify, not looking for a comparison on how it drives vs how a 991 drives. More so comparison on if u line them up, or going down a long straight at the track, or on a highway in Mexico
Old 02-07-2017 | 11:25 PM
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Originally Posted by TheSilverFox
Have zero seat time in a 991 so cannot comment on differences between 991 and a 997 GT3 with build. Currently have a .2 GT3 with 4.0 engine package. It definitely transforms and already very capable car. Biggest improvement to me is low RPM grunt, more torque for sure. Having more torque and power in a GT3 flat 6 NA package is the deal.

It's also loud as hell which only improves the experience, GMG headers, side pipe delete and most likely burnt out cats. Wife has refused to ever get in it, that alone might be worth the price of admission
Nice to see someone else from Chicago, don't see many GT3s around these parts.

Who did your 4.0 build?
Old 02-07-2017 | 11:42 PM
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Originally Posted by sraz786
Nice to see someone else from Chicago, don't see many GT3s around these parts.

Who did your 4.0 build?
Was done by previous owner at 911 Design in CA.

Unfortunately being in Chicago the cars are sleeping for a few months.
Old 02-08-2017 | 01:03 AM
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Originally Posted by TheSilverFox
It's also loud as hell which only improves the experience, GMG headers, side pipe delete and most likely burnt out cats. Wife has refused to ever get in it, that alone might be worth the price of admission
No joke here. I caravanned with TSF behind his 4.0 up Lake Shore for many miles. It shakes your bones. Beastly.
Old 02-08-2017 | 01:19 AM
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would like to check out the 4.0 sw someday - chicago get together?


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