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How much NA power is technically possible from a flat six?

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How much NA power is technically possible from a flat six?

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Old 03-10-2018, 03:13 PM
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96redLT4
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Default How much NA power is technically possible from a flat six?

The 'standard' Porsche power adjustments of 15-20 hp with new models got me thinking. I think a big complaint throughout the models is a perceived hp/torque deficit compared with other car makers. Many of them obviously resort to turbo/super charging but lets face it. 550-700 horsepower is becoming relatively commonplace in the performance car segment. Can we ever hope for a 600-700 hp normally aspirated Porsche or is it simply not technically possible? Torque is what you feel at the seat of your pants, and is 'boosted' power necessary to really make a difference here?? Would appreciate insight from the more technically minded here.

Jim
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Old 03-10-2018, 03:19 PM
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sampelligrino
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I am not technical minded but I don't think I would want any more HP in the 4.0L, it's already far more than enough for me.. Just happy PAG still makes this engine/flat sixes

While some may complain about lack of HP in 911s (haven't heard this too much honestly), it makes up for that with the best driving dynamics and many other tanigble/intangible factors that make the 911 one hell of a sports car

If you want torque/feel power from the seat of your pants, try a Tesla in ludicrous mode.. just about the entire future of the car industry is headed that way for better or worse
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Old 03-10-2018, 03:36 PM
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ExMB
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Originally Posted by 96redLT4 View Post
550-700 horsepower is becoming relatively commonplace in the performance car segment.
Jim
Please show us a NA 6 with that kind of power.
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Old 03-10-2018, 04:12 PM
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GrantG
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Originally Posted by 96redLT4 View Post
The 'standard' Porsche power adjustments of 15-20 hp with new models got me thinking. I think a big complaint throughout the models is a perceived hp/torque deficit compared with other car makers. Many of them obviously resort to turbo/super charging but lets face it. 550-700 horsepower is becoming relatively commonplace in the performance car segment. Can we ever hope for a 600-700 hp normally aspirated Porsche or is it simply not technically possible? Torque is what you feel at the seat of your pants, and is 'boosted' power necessary to really make a difference here?? Would appreciate insight from the more technically minded here.

Jim
The current RS at 520hp is fairly close to the reasonable limit for an NA Flat 6. More NA power is easily possible with more displacement and more cylinders (Ferrari has 800hp V12 and doubling the current RS would give 1,040 hp 8.0L Flat-12 if the crank could sustain it).

But more NA power requires more revs (not a huge amount more possible than 9k with 4.0 Flat-6) or more displacement (not much more than 4.0 possible with Flat-6. As the cylinders get larger, the engine is less efficient and itĺs more difficult to rev).

Best bet for more NA power is more smaller cylinders in a Flat-8/10/12/16 which have all been done before, but not easily packaged in the back of a 911...
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Old 03-10-2018, 04:43 PM
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In this interview, AP mentioned the race version of the 4.0L without restrictors does more than 600hp. I doubt this would be possible for a street car simply from the emissions standpoint (not to mention reliability).

At about 5:35 - 5:45

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Old 03-10-2018, 05:13 PM
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Originally Posted by manitou202 View Post
In this interview, AP mentioned the race version of the 4.0L without restrictors does more than 600hp. I doubt this would be possible for a street car simply from the emissions standpoint (not to mention reliability).

At about 5:35 - 5:45

https://www.youtube.com/watch?v=HZWBGY6LeUQ
Straight from the source, nice interview. Previously I've also read that the GT3 R engine makes about 590PS without restrictor and 600 in the RSR, also a 9500 rpm redline.

Beyond emissions that doesn't appear to be feasible in the road cars unless you want to deal with similarly strict engine and gearbox rebuild intervals as the race cars.
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Old 03-10-2018, 05:45 PM
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I don't want that much power except if I was drag racing, racing on a track with long straights or just wanted bragging rights. My 370 hp 991.2 is way more for the streets that I drive around. I blow everyone away.
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Old 03-10-2018, 06:09 PM
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Originally Posted by ExMB View Post
Please show us a NA 6 with that kind of power.
I guess Chevrolet Ford and Ferrari come to mind. Not sixes, but similar displacement small block V8s. I think I read somewhere that the Chevrolet V8 LS motor is a smaller package or weighs less (someone correct me if I'm wrong) than the Porsche flat 6.

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Old 03-10-2018, 06:27 PM
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Originally Posted by 96redLT4 View Post
The 'standard' Porsche power adjustments of 15-20 hp with new models got me thinking. I think a big complaint throughout the models is a perceived hp/torque deficit compared with other car makers. Many of them obviously resort to turbo/super charging but lets face it. 550-700 horsepower is becoming relatively commonplace in the performance car segment. Can we ever hope for a 600-700 hp normally aspirated Porsche or is it simply not technically possible? Torque is what you feel at the seat of your pants, and is 'boosted' power necessary to really make a difference here?? Would appreciate insight from the more technically minded here.

Jim
Are you talking OEM power or race power? Because a standard RS will make 550-570 easely just by forgetting emissions.
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Old 03-10-2018, 06:29 PM
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Originally Posted by 96redLT4 View Post
I guess Chevrolet Ford and Ferrari come to mind. Not sixes, but similar displacement small block V8s. I think I read somewhere that the Chevrolet V8 LS motor is a smaller package or weighs less (someone correct me if I'm wrong) than the Porsche flat 6.

J
Apples and oranges: 6 vs 8. Too much else involved; piston speeds, etc.

Last edited by ExMB; 03-10-2018 at 07:31 PM.
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Old 03-10-2018, 06:42 PM
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The 991.1 cup converted to 4L I drove last week put down over 500 rwhp on race fuel, which I guess would translate to around 600hp at the crank ... but it don't think it was carb compliant.
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Old 03-10-2018, 07:24 PM
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If the stock 991.2 GT3 engine is putting down 460 whp SAE on a dynotjet on 93 oct at 68F, I think 500-510whp after LTH, better intake filter, catless/100 cel exhaust, and tune even at 95F is douable. And one could always use E85 or 100 oct just to make sure... 510whp at 12% drivetrain loss would be about 580hp.
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Old 03-10-2018, 07:49 PM
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I wait patiently for the day that I can use the HP I have to actually turn faster laps. Truth is, the car is not stopping my progress, I am.
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Old 03-10-2018, 08:44 PM
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In terms of specific output the GT3/GT3 RS engines already do pretty well for NA sports cars, the .2 GT3 RS with 128.38 bhp/l is not far behind the NA V8's in the 458 Speciale or 918 Spyder and ahead of many NA engines in road-legal sports cars (not that there are many left). I don't think there's much headroom without going turbo or hybrid, and that's ignoring emissions. Power/weight overall is a different matter though - making the car lighter would be an area where you'd hope Porsche puts more emphasis in the future.
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Old 03-10-2018, 08:53 PM
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Originally Posted by RennOracle View Post
Are you talking OEM power or race power? Because a standard RS will make 550-570 easely just by forgetting emissions.
OEM smog legal 4yr/50K warranty
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