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Let's not be silly. When I talk about torque winning races while horsepower selling engines...I'm talking about the same basic engine and moving the power range around.
Hacker....you honestly think a BMW Formula One engine would even be able to move a 928 with a 928 transmission around a race track even one lap? You honestly think BMW would choose to build an engine like that, if they were not following very specific rules that required that configuration?
Mark, of course average power is important, but there's more to the story than just that. How many extra gear shifts does a peaky high power engine require over an engine with broader torque? How many corners is one gear going to be too short and another gear too tall and make the peaky engine fall off out of the sweet spot?
I've told the story about the two state of the art RSR's running at Sebring....one with a 5 speed transmission and 340 hp....the other with a 6 speed and 420 hp, a couple of times. I was there. I was one of the crew chiefs. I was the main mechanic. It was I that was asked if we could switch the two engines, the night before the race....to put the higher torque engine into the brand new 993 RSR with the factory drivers and put the higher horsepower peaky engine into the "paying driver's" RSR. There wasn't a "tiny" difference between the two engines....it was about ten car lengths in 1/2 of a lap!
Can someone please find that story and post it here, so I don't have to repeat it, again?
Take a look at Andy's dyno results from 8 years ago...compare them with Catorce's dyno results, from last week. (Ignore the fact that Andy's engine was running on street fuel when that pull was made, versus Catorce's engine running on 110 octane.) How about someone taking the time to graph those two engines together? One a street engine in front of an automatic transmission and the other a dedicated race engine?
Which of those two engines is going to be faster around Willow Springs or Fontana' with 928 gearing and the same weight/ suspension/tires/driver?
Yeah, it wouldn't even be a contest....the additional torque from Andy's engine would make Catorce think a spark plug wire fell off his engine.
I've got news for you all, if this current manifold and engine is today's "state of the art", 928 engine development has gone backwards in 8 years....
So max torque around 16,000 rpm... Put it in a black box with a 3:1 gear reduction and you've got 690 lb/ft at around 5000 and 740 bhp at 6000, right?
More RPM's is never a bad thing...
Originally Posted by jcorenman
Nonsense. Plot wheel torque against wheel RPM in each gear, that will tell the story.
The flatter the torque curve, the more linear the power band and in general the more power you will have available at any given RPM. This is great for street cars driven in the real world.
The peakier your torque curve the narrower the powerband, and in general, more parts will break. This is great for race cars that are tuned to operate in specific RPM ranges on a track.
After all, it isn't high rpm power that breaks parts (unless parts are spun beyond rpm spec), it's low end torque that stresses components, hence why the 928 Variocam experimental heads kept breaking.
Back on topic. It will be interesting to compare both of these intakes when they are truly finished and operating in 928s instead of on engine dynos.
Oh no.. that is completely incorrect. Ill let you do some plotting of a HP curve, but a flat torque curve is a rising HP curve, (peaky) . he power band is NOT linear , and it is counter intuitive, unless you use a little physics. think of power being the capacity of a car to accelerate at ANY vehicle speed. think about it.. if torque was flat, hp is rising with RPM, which is "peaky".
when you grasp the idea that you want the most average HP or the most HP (peroid) at any vehicle speed vs another car, or even in another gear, you have full understanding of maximizing performance on the track.
here are two HP curves. one with a flat torque curve and one that is not flat. which one would have more average HP at the track, all speeds around the track using the right gear?
This is a comparison of a GT3 cup car with 385 hp and the porsche 928 with 372hp. you still think you would want the flat torque curve? thats the GT3 by the way. again, flat torque means rising peaky HP. the 928 in this example even vs close gear of the cup car is a better engine package for acceleration anywhere on the track , at any speed. it produced more usable hp at any vehicle speed , contrary to what you said above. Look at the average HP for the RPM range of use for the 928 vs the GT3 cup.
Originally Posted by The Forgotten On
The flatter the torque curve, the more linear the power band and in general the more power you will have available at any given RPM. This is great for street cars driven in the real world.
The peakier your torque curve the narrower the powerband, and in general, more parts will break. This is great for race cars that are tuned to operate in specific RPM ranges on a track.
After all, it isn't high rpm power that breaks parts (unless parts are spun beyond rpm spec), it's low end torque that stresses components, hence why the 928 Variocam experimental heads kept breaking.
Back on topic. It will be interesting to compare both of these intakes when they are truly finished and operating in 928s instead of on engine dynos.
Last edited by mark kibort; 11-29-2017 at 06:05 PM.
Let's not be silly. When I talk about torque winning races while horsepower selling engines...I'm talking about the same basic engine and moving the power range around.
Moving the HP around the RPM range is a different story , than focusing on the advice or question of whether its better to have more or less torque in an engine. the rear wheel forces are DETERMINED by HP (or indicated, perfectly, by "HP") this means, if you EVER have more HP at any speed, you will accelerate faster. HP is the capacity of a car to accelerate at any speed, period! its as solid as a definition as the formula for 'energy" which is " the capacity to do work"
Hacker....you honestly think a BMW Formula One engine would even be able to move a 928 with a 928 transmission around a race track even one lap? You honestly think BMW would choose to build an engine like that, if they were not following very specific rules that required that configuration?
Greg, if you are going to make comparisons, make them scientifically fair. yes, the BMW engine, like alll engines need to be matched with the appropriate gear box ratios that optimize HP. if the RPM range is 2x higher, then all you would need to do is change the rear differential gearing. the wide gears of the 928 wouldnt be optimal, so you would lose HP average, but it , based on the curves, would be plenty powerful and fast to beat most at willow springs. (the average might not be 750hp, it might only be 600hp)
Mark, of course average power is important, but there's more to the story than just that. How many extra gear shifts does a peaky high power engine require over an engine with broader torque? How many corners is one gear going to be too short and another gear too tall and make the peaky engine fall off out of the sweet spot?
Greg, so you asked the question, let me answer. "NONE" the gear shifts are strictly determined by the gear spacing. you would always be taking the RPM to redline and shifting. a peaky engine or a flat HP engine , would be the same. the differcen is based on the gear spacing, and that would determine the average HP.. you ask another question regarding gear spacing. let me answer that as well. if the gearing is appropriate to the engine as the 928 is, and the GT3 cup car is. they both keep the engine in the max hp range almost perfectly. i calculate for most cars regardless of their HP curves, that you retain 93% of max HP as an average. so going into a turn at willow springs (say turn 2) i down shift 2 times with the 928 and 3 times with the GT3, and both are at near optimal points on the HP curve to not only control the car with LSD going into the turn (trail braking and rear wheel stability) BUT, also allows for optimal exit HP . i have Never seen a turn where i have not been at an optimal HP on an exit of a turn. i have 100s of hours of video, and i challenge you to find one point were i was not optimal for hp on the exit. search the GT3 cup car videos... you will find the same thing. why? because the gear box matches the HP range and provides optimizations
I've told the story about the two state of the art RSR's running at Sebring....one with a 5 speed transmission and 340 hp....the other with a 6 speed and 420 hp, a couple of times. I was there. I was one of the crew chiefs. I was the main mechanic. It was I that was asked if we could switch the two engines, the night before the race....to put the higher torque engine into the brand new 993 RSR with the factory drivers and put the higher horsepower peaky engine into the "paying driver's" RSR. There wasn't a "tiny" difference between the two engines....it was about ten car lengths in 1/2 of a lap!
Can someone please find that story and post it here, so I don't have to repeat it, again?
Greg, i remember that story well.. did you not read my similar story in this thread?? i beat a car with the peaky 420rwhp with my 370rwhp engine because it had a broader HP curve (and you and i are saying the same thing, in that the bigger relative torque, provides a bump in HP down at the lower RPM range. clearly , it is the same story as you told, but on a 928 vs a peaky S2000 turbo, so i get it. now, there was NOT a huge difference by the way. the average HP was 330 vs my 350rwhp. so there was not a difference of more than a few tenths. i suspect , if you research your conditions for the 911s at Sebring, you would find a similar physics difference. the reason for the larger time diff, was probably due to the driver, because average HP is an easy variable to detect and apply to your example
Take a look at Andy's dyno results from 8 years ago...compare them with Catorce's dyno results, from last week. (Ignore the fact that Andy's engine was running on street fuel when that pull was made, versus Catorce's engine running on 110 octane.) How about someone taking the time to graph those two engines together? One a street engine in front of an automatic transmission and the other a dedicated race engine?
Which of those two engines is going to be faster around Willow Springs or Fontana' with 928 gearing and the same weight/ suspension/tires/driver?
Yeah, it wouldn't even be a contest....the additional torque from Andy's engine would make Catorce think a spark plug wire fell off his engine.
I've got news for you all, if this current manifold and engine is today's "state of the art", 928 engine development has gone backwards in 8 years..
Greg the answer is easy... which ever one has the most average HP for the 3 -4 gears used at fontana, and the 3 gears used at Willow, will win the race its very simple.
just take the HP values from 4500, 5500 and 6500 and average them together.. what do you get??????????????????? compare the two and get back to me.. give me the link and ill do it for you (andy's engine dyno run) its ALL about average HP over the used RPM range!! edit: the CATORCE Average HP from 4500 to 6500 was looking like 515rwhp... does the Andy HP curve look higher or lower???? here is your answer right there. who ever is higher will win at Willow or Fontana. by the way, ill be at Fontana for an SCCA Majors race in january 2018
.
Last edited by mark kibort; 11-29-2017 at 01:33 PM.
Nonsense. Plot wheel torque against wheel RPM in each gear, that will tell the story.
How is that "nonsense" by plotting wheel torque against RPM , you are effectively showing HP.. by definition that is what HP is : Force x Velocity. if you have more HP , you have more force at any speed. so, how is this nonsense? HP is the vehicile's capacity to accelerate at any vehicle speed. this is not "nonsense" it is a basic newtonian identity.
I gave an example too. the Ferrari HP curve. notice the torque peak ... it will never be used at any speed to accelerate the car optimally,... in that car and engine package, go ahead, take all wheel torque values at any RPM and you will clearly see it is maximized in the max HP range at any vehicle speed. This is not a theory, it is a fact that i can prove from any perspective.
The bottom line, the entire goal is to optimize HP for any speed range or RPM range. this is why you see me race the 928 and never hit the throttle WOT, or am at max braking decel, unless the engine is between 4500rpm and 6500rpm,
That looks so nice! i know that car!! where are you running it? btw, what was done to the front fenders. they look really wide , but very stock'ish too? I know the rears are GTS style modified, but what about the front.
Mark, I knew you'd appreciate Ronn's car, and why I posted it.
I bought it from him with the fenders so I do not know their origin. Since Ronn worked and built the car at 928 International, perhaps Mark Anderson would know.
why do you think it would be too big for your 5 liter? I'm betting it would work amazingly well!
Based upon the RPM of the torque peak, the runner diameter appears too big for a smaller motor. Just a guess of course.
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
Did you want some ideas about intake systems or did you just want another debate about torque versus horsepower?
It gets old.
Of course. i am narrowing down options, but of course understanding the goals is important. (hence the slight diversion to a HP optimization discussion) ive seen how these intakes help, not only our engines, but once much smaller (like the mustang 5.0L and Aston 4.3L) the stock intake is good for what it was designed for, but for extracting all the potential HP available, its not very good at all.
But, the fix is something custom. much of the technology is transferable, (why reinvent the wheel) so, its why im pursuing the AMV8 intake. I still have a lot of hurdles to cross. I dont think Carl's is optimal, but it 80% there. (and it fits) the question is what it costs and what i need to do to make it work (accessories)
as far as the HP discussion. You are a sharp guy. what i have posted is pure and factual. you can learn this on the track or you can learn this from the laws. they are never contradictory.
your example of a 350hp car beating a 420hp car of the same make , has been seen by some of my examples. in the end, its about average HP utilized over a lap. you might want to produce some dyno runs that show a net difference of a higher torque engine of a lower HP that has more Average HP than a higher hp , lower torque engine of the same type. the differences should be subtle and any blow out , would be due to other factors. (the best you might hope for would be parity, between these two engines you reference) I know you are promoting the wider band of usable, much higher HP and that is the right idea, but i do think the intake designs both from you and carl achieve this with great results (even if you have a wider HP curve that might make it better for street use)
Originally Posted by SwayBar
Mark, I knew you'd appreciate Ronn's car, and why I posted it.
I bought it from him with the fenders so I do not know their origin. Since Ronn worked and built the car at 928 International, perhaps Mark Anderson would know.
Based upon the RPM of the torque peak, the runner diameter appears too big for a smaller motor. Just a guess of course.
they look like andersons flares.. very cool!!! maybe the same guy did Rons. yes, much appreciated!
as far as the data from Carl, and what ive seen by the other designs on even smaller V8s with near the same cam lift and profile, the intake would most likely help a 5 liter as well. probably in a HUGE way. i hope we see a test soon to confirm this! the runner diameters are stilll smaller than what ive been measuring on the AMV8 intake, and thats only a 4.3 liter. (which is not as oversquare as the 928 engine)
Quote:
Originally Posted by Rob Edwards
IBTM.
Where's it going?
It _was_ going to any number of beaten-to-death HP vs. torque discussion threads. But 33 posts on, it's _become_ a HP vs. torque discussion. So I guess it can stay right here.
as far as the data from Carl, and what ive seen by the other designs on even smaller V8s with near the same cam lift and profile, the intake would most likely help a 5 liter as well. probably in a HUGE way. i hope we see a test soon to confirm this! the runner diameters are stilll smaller than what ive been measuring on the AMV8 intake, and thats only a 4.3 liter. (which is not as oversquare as the 928 engine)
What is the AM runner inside-diameter where it meets the head?
If it's rectangular, what are the dimensions so as to calculate its area?
Out of curiosity only, what are the AM runner lengths? Do you know the length from the AM port entrance of the head to the intake valve lip?
That is a nice looking intake Carl made. Who the hell needs a closed hood?
i know huh! if this works well, it coud just stick out of the hood. Ill cut a big rectangle for it! :ROFLMAO:
Originally Posted by SwayBar
What is the AM runner inside-diameter where it meets the head?
If it's rectangular, what are the dimensions so as to calculate its area?
Out of curiosity only, what are the AM runner lengths? Do you know the length from the AM port entrance of the head to the intake valve lip?
Yes, 11" runner length and they are 32 x 53mm at the head.. much larger at the bell mouth.
Originally Posted by Rob Edwards
It _was_ going to any number of beaten-to-death HP vs. torque discussion threads. But 33 posts on, it's _become_ a HP vs. torque discussion. So I guess it can stay right here.
It's all about HP. sometimes we have to talk about torque, just to show why you dont need to talk about torque.
JUST came in the mail today.........I have the VERY SOLID Steel head template to mount the intake adapter to it and do the cutting and welding with. Its a very impressive piece.
So, Greg thinks i should make this all fit , pointing up front. i guess i could, as Bob said, as i have to cut the legs off this thing anyway....... i can make them any length i want to cant the intake forward. the draw back is that i for sure will have to change the oil filler inlet and the temp sensors. if i point it backward, im drawing air from the 2nd most highest pressure zone, the base of the windshield... just trying to find the easiest way to make this fit, AND use the stock components so this is a bolt on affair, after its all welded up.
either way, ill need some MAF connection wire extension and an extension of the throttle body linkage.
Oil filler neck and water crossover mods are the least of your hurdles. Piece of cake! You're going to be using Alpha N with your new sharktuner, the lead to the MAF connection is 3 feet long. Order one now from John so you have it in hand while you're laying everything out.
11-29-2017, 02:53 AM
