8 cylinder front engine iconic vehicle
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By Crumpler
#125586
As I slog through performance upgrades, let me just ask this question to the collective:
Why didn’t Porsche do a better job with my 5 liter displacement V8?

Yes yes, clean sheet design, fastest production car of the time, etc.

But really, MY 86, 288hp?
These were arguably the best engineers the world could offer.

Was it choked down because of contemporary technology v. emissions regulations?
Was it mapped to provide smooth and reliable (read boring) service for the clientele?
Was it, God forbid, held back so it would not outshine the beloved 911?

Is it an unfair question, and have I been jaded by contemporary v8 and smaller engine power outputs?
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By worf
#125591
Crumpler wrote: Sat Jan 01, 2022 11:27 am As I slog through performance upgrades, let me just ask this question to the collective:
Why didn’t Porsche do a better job with my 5 liter displacement V8?

Yes yes, clean sheet design, fastest production car of the time, etc.

But really, MY 86, 288hp?
These were arguably the best engineers the world could offer.

Was it choked down because of contemporary technology v. emissions regulations?
Was it mapped to provide smooth and reliable (read boring) service for the clientele?
Was it, God forbid, held back so it would not outshine the beloved 911?

Is it an unfair question, and have I been jaded by contemporary v8 and smaller engine power outputs?
I think you need to refresh your memory of the automotive and computer context of that time.

Chevy was getting a "tire-shredding" 225 bhp out of their 'H.O.' 5.7 liter V8 in 1987.

At the same time Porsche was getting 320 bhp out of their 5.0 liter RoW motor.

The 288 bhp 32v motor was still way, way better than the Chevy even if it was just as choked by the emissions technology of the day.
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By Sazerac
#125645
worf wrote:
Crumpler wrote: Sat Jan 01, 2022 11:27 am As I slog through performance upgrades, let me just ask this question to the collective:
Why didn’t Porsche do a better job with my 5 liter displacement V8?

Yes yes, clean sheet design, fastest production car of the time, etc.

But really, MY 86, 288hp?
These were arguably the best engineers the world could offer.

Was it choked down because of contemporary technology v. emissions regulations?
Was it mapped to provide smooth and reliable (read boring) service for the clientele?
Was it, God forbid, held back so it would not outshine the beloved 911?

Is it an unfair question, and have I been jaded by contemporary v8 and smaller engine power outputs?
I think you need to refresh your memory of the automotive and computer context of that time.

Chevy was getting a "tire-shredding" 225 bhp out of their 'H.O.' 5.7 liter V8 in 1987.

At the same time Porsche was getting 320 bhp out of their 5.0 liter RoW motor.

The 288 bhp 32v motor was still way, way better than the Chevy even if it was just as choked by the emissions technology of the day.
While the above is all true with resepct to the 80s, it's what makes the Italian cars from the mid-70s so fascinating to me. For some comparison points:
1.) Lamborghini Urraco 3.0L V8 300 hp (ca. 1970)
2.) Maserati Bora during 4.9L V8 320 hp (ca. 1973?)

Of course these values were likley all prior to any emissions smothering, but I find the numbers nonetheless stunning. Oh, but, just to make clear, I wouldn't trade my 928 GT for a 70s Italian GT...
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By linderpat
#125659
As to the 911 issue, do a search. The 928 was the most powerful and fastest Porsche made during its run, with a couple of very rare exceptions for the 930 (not all of them either) and of course the vaunted 959. The 928 was Porsches top dog, and as Worf said, one of the top performers in the world at its time
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By Crumpler
#125672
Nah.
Dave, my new tuning book says it’s just air and spark. ;)
Engineers Spingineers.
Herr Bott didn’t try hard enough.

So we’re going with technology made hp easier?
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By worf
#125708
Crumpler wrote: Sat Jan 01, 2022 8:05 pm So we’re going with technology made hp easier?
It’s either that or learn how to keep 8 (or 10 or 12) downdraft carbs perfectly tuned enough that you can run your 9k-rpm engine for more that just qualifying before it grenades a cylinder.
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By Crumpler
#125713
Obviously you are right and I am playing devil’s advocate, but we are talking sturdy EFI by mid-80’s.
I believe my block manufactured late 85 had knock and Hall sensor holes, sitting unused right?

Ken used their code and EPROM technology two decades later and found 55 hp they left on the table, with pretty trivial hardware changes.

It’s fishy, Dave.
:silenced: :wink:
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By Geza-aka-Zombo
#125737
A couple of random thoughts:

It's not valid to compare performance numbers for the early '70s and before, to today. They changed from SAE Gross figures (not the final factory configuration - air cleaner, exhaust, belt driven accessories, etc.) to SAE Net (factory configuration) around 1972. The example appears to show the delineation with the Urraco making 100HP/Liter (probably gross) vs. the Bora making 65 (probably net).

For NA engines, it's specific torque (torque/engine size) that tells the most about the development of engines, IMO. Specific Power (HP/engine size) is very important, but doesn't tell the full story, as Power is a function of engine speed in addition to Torque, whereas Torque is only a function of displacement and how well the displacement is managed.

Here's a chart I put together showing how the specific torque and power numbers have changed over the years. Based on the examples shown, since the late '90s, there hasn't been a huge improvement in specific torque. It appears most of the modern technologies (VVT & lift, intake runner management, etc.) are geared at broadening the torque curve over a greater RPM range, thus improving the specific power numbers, which have been improving.

Image
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By worf
#125750
torque X rpm = power
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By Geza-aka-Zombo
#125773
worf wrote: Sun Jan 02, 2022 12:57 pm torque X rpm = power
Yes.

As most here are probably aware: HP = Torque (in Lb-Ft) X Engine Speed (in RPM) / 5252 - Hence, every engine always makes the same value of HP and Torque @ 5252 RPM.

For useless trivia, this is how this equation is derived.

A HP is defined as 550 Lb - Ft per Second. Back in the day, it was determined that an average horse has the power to lift (using a pulley system) 550 Lbs, one foot in 1 second. One HP. To convert to an engine's HP, we just have to work out the units as follows:

HP = 550 Lb-Ft/sec = Torque in Lb-Ft X Engine Speed Rev/Min X 1 Min per 60 sec X 2 Pi Radians per Revolution - Radians are unitless, so, doing the math and canceling out the units, you get to equation we use: HP = Torque (in lb-ft) X RPM / 5252. The 5252 comes from 550 X 60 / 2 Pi
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By worf
#125914
Geza-aka-Zombo wrote: Sun Jan 02, 2022 4:25 pm
worf wrote: Sun Jan 02, 2022 12:57 pm torque X rpm = power
Yes.

As most here are probably aware: HP = Torque (in Lb-Ft) X Engine Speed (in RPM) / 5252 - Hence, every engine always makes the same value of HP and Torque @ 5252 RPM.
The point being that making torque at higher RPM results in more power. That's why the little EYEtalian motors make big power numbers from small displacement. It's why the 80's US motors are dogs.

It's why F1 motors (in the normally aspirated '00s) could make a thousand horsepower with ~250 lbf-ft.
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By Geza-aka-Zombo
#125919
Since engine displacement basically determines torque on a NA engine, lets look at RPM and power via 2 somewhat fictitious engines, both 2L 16V inline 4 cyl. - Engine 1: fairly conventional 6000rpm, 150 Lb-Ft, 160 HP - Engine 2: High strung, Honda S2000 like 9000rpm, 150 Lb-Ft, 240 HP, both bolted to the same transaxle.

Under normal driving, both would be about the same. Actually, E1 would probably feel stronger as the torque curve would be more biased towards the lower, more often used part of the RPM band. A redline shift to 3rd would get you to say 60mph in E1; this same shift would be at 90mph in E2, because of the extra available RPM. That would be silly, so, for E2, we shorten the final drive ratio by 50% to take advantage of the available rpm. If E1 is running a 0.380 FD, E2 can run a 0.570 and now both have a 2nd to 3rd redline shift at 60mph.

With both now having reasonable gearing for their RPM range, E2 has a massive advantage as the shorter final drive now amplifies engine torque across all rpms. In any gear at any speed, 50% more tractive force in being put to the ground with E2 due to the gearing advantage. That is what power, by way of increased rpm gets you.
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By maddog2020
#126272
looking at the newer engines that are making really good hp and torque, they are taking advantage of variable cam timing and more control over ignition events with coil on plug. You can make huge power with the right cams, however if they don't have a method to advance or retard they will idle and drive like crap.being able to control valve opening and closeing events is huge. more power with less cam.
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By worf
#126366
Crumpler wrote: Sun Jan 02, 2022 8:14 am Obviously you are right and I am playing devil’s advocate, but we are talking sturdy EFI by mid-80’s.
By "sturdy" you mean an early 8-bit MCU running only slightly faster than a snail can ooze down hill. Remember that the 2.3 LH (87+) is so slow that it has to drop tasks above 4200 (IIRC) rpm and it's faster than your LH 2.2.

Crumpler wrote: Sun Jan 02, 2022 8:14 am I believe my block manufactured late 85 had knock and Hall sensor holes, sitting unused right?
Your block has holes in the valley that were used to mount the air guide. In the '87+ they decided to use two of those holes for knock sensors and as a result had no where to mount the air guide except to the bottom of the plenum.

The Hall Sensor is a hole in the right-side back plate between the block and the cam gear.

Crumpler wrote: Sun Jan 02, 2022 8:14 am Ken used their code and EPROM technology two decades later and found 55 hp they left on the table, with pretty trivial hardware changes.
It’s fishy, Dave.
:silenced: :wink:
Does Ken's "found" horsepower compromise the emissions warranty on the cats? Or compromise the longevity of the motor when something else is broken or deteriorated? What about emissions on an emissions dyno?

Ken doesn't have to worry about any of that shit.

Note: I am not knocking Ken. He does tremendous work. But, don't assume that Porsche was just lazy about the design. Now, you can quite likely throw some shade on the original EZF and LH code as it is highly unlikely that the propeller heads that wrote the code were also performance car nuts working without bosses whose fists were crushing their nuts.
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By worf
#126368
maddog2020 wrote: Tue Jan 04, 2022 9:38 am looking at the newer engines that are making really good hp and torque, they are taking advantage of variable cam timing and more control over ignition events with coil on plug. You can make huge power with the right cams, however if they don't have a method to advance or retard they will idle and drive like crap.being able to control valve opening and closeing events is huge. more power with less cam.
Plenty of computer cycles to throw at individual control of each cylinder for fuel and timing along with multiple wide-band oxygen sensors. Completely variable intake runners. Coil-on-plug. Faster sensors of all types. Better measurement of air. Better modeling of combustion before heads and pistons get made. Higher compression because of the better modeling and control.

Folks forget that the 928 fires injectors more-or-less all at once regardless of intake valve position and that spark timing still has a significant 'mechanical' component to it.

Your Beast is a paragon of what can be done(*) with thoughtful application of modern engine management technology.

(*) Assuming you'd ever quit fucking with it... :hiding: :silenced: :tongue:
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By Geza-aka-Zombo
#126413
worf wrote: Tue Jan 04, 2022 3:29 pm
Plenty of computer cycles to throw at individual control of each cylinder for fuel and timing along with multiple wide-band oxygen sensors. Completely variable intake runners. Coil-on-plug. Faster sensors of all types. Better measurement of air. Better modeling of combustion before heads and pistons get made. Higher compression because of the better modeling and control.
If you look at the chart above and compare the 928GTS engine and M96 in the 986 (which was designed and developed while the 928GTS was still manufactured), the M96 has a 7% improvement in specific torque and a whopping 26% improvement in specific power.

I think the increased compression ratio (to 11:1) is responsible for most of the torque improvement in the M96. The other technologies you mentioned, such as coil on plug, variable valve timing, better fuel injection control, etc. that were incorporated into the M96 enables that improved torque to spread over a wider RPM band yielding the large specific power increase. Only variable intake manifold tricks are missing on this particular M96 - I think they added that with later iterations.
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By worf
#126439
Geza-aka-Zombo wrote: Tue Jan 04, 2022 6:51 pm If you look at the chart above and compare the 928GTS engine and M96 in the 986 (which was designed and developed while the 928GTS was still manufactured), the M96 has a 7% improvement in specific torque and a whopping 26% improvement in specific power.
Thing is though, the M96 was a new design for the Boxster, while Porsche basically did nothing to the 928 motor after 1987 (GT cams and a little stroking for the GTS don't count as more than nothing.) IIRC the M96 was Porsche's first motor to sport continuously variable intake runners.

By the 90's Porsche could have applied the next generation of engine management technology to the M28 if they'd wanted to. But, by the end of the 80s the 928 was a lame duck and everyone at PAG knew it; it wasn't going to get the R&D dollars required for any non-trivial changes.

And we know that the GTS motor was halfhearted, poorly-executed effort where 20%+ of the motors were replaced under warranty for excessive oil consumption.

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