Non-turbo 428rwhp FD build up and history
03-13-11, 12:25 PM
#156
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Hey Logan, when you put the stock intake gasket on, sealing the semi-pp's right at the housings, did you notice any significant improvement in low-end power/torque over the semi-pp's open? Did it behave strictly like a street-ported engine? Great job on more testing!!
03-13-11, 01:05 PM
#157
Old [Sch|F]ool
Somewhat like t-von, I can't tell you why, although I knew at one point, but it is wrong to say that torque is solely dependent on displacement. The lower the bore:stroke ratio, the more torque is produced and the higher the ratio, the more top end power is made. That's simply true as far as I have known these past 60 years...
Gordon
Gordon
However, smaller bores have higher thermal efficiency (less surface area) and have better combustion characteristics (maximum distance from plug is lower - fireball has less distance to travel during the critical first thirty or so degrees after the spark, while the piston is very close to TDC) and more detonation resistance (fast burn = less likely to detonate). All reasons why high economy engines tend to be small bore/long stroke, but also all things that will contribute to higher torque per liter at reasonable RPM.
At unreasonable RPM, larger bores allow for larger valves, allowing for higher VE, so short stroke engines win over. Interestingly, people find that long stroke/small bore engines tend to produce higher inlet tract velocities, all else being equal. Theory is that the longer stroke means the air has further to go in the chamber during the intake stroke. So this higher intake velocity helps long stroke engines have higher VE at sub-6000rpm engine speeds.
None of this neat stuff is available to us in the rotary world, where geometry is pretty much fixed. It does help explain how 13Bs make more power than 12As out of proportion to the displacement increase, though - better combustion since the chamber is becoming less oblong.
03-13-11, 01:54 PM
#158
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ExactlyHowever, smaller bores have higher thermal efficiency (less surface area) and have better combustion characteristics (maximum distance from plug is lower - fireball has less distance to travel during the critical first thirty or so degrees after the spark, while the piston is very close to TDC) and more detonation resistance (fast burn = less likely to detonate). All reasons why high economy engines tend to be small bore/long stroke, but also all things that will contribute to higher torque per liter at reasonable RPM.
At unreasonable RPM, larger bores allow for larger valves, allowing for higher VE, so short stroke engines win over. Interestingly, people find that long stroke/small bore engines tend to produce higher inlet tract velocities, all else being equal. Theory is that the longer stroke means the air has further to go in the chamber during the intake stroke. So this higher intake velocity helps long stroke engines have higher VE at sub-6000rpm engine speeds.
03-13-11, 02:40 PM
#159
But the amount of force is different
We are dealing here with pressure, you have to apply it to area(bore) to become force. And as I said, on given displacement as you increase one parameter, you have to decrease other one and vica versa
Also, you can´t do such simplification, force has to be perpendicular to arm from center of rotation and this happens at only one moment
If it was such easy, we would build engines with ridiculous ratio between bore and stroke and achieving huge torque, right?
We are dealing here with pressure, you have to apply it to area(bore) to become force. And as I said, on given displacement as you increase one parameter, you have to decrease other one and vica versa
Also, you can´t do such simplification, force has to be perpendicular to arm from center of rotation and this happens at only one moment
If it was such easy, we would build engines with ridiculous ratio between bore and stroke and achieving huge torque, right?
You stated that stroke had nothing to do with torque. I was simply stating that assuming ALL OTHER VARIABLES are equal, the motor with the longer stroke will produce more torque. Again, argue all you want, but you're arguing with physics at this point, not me. 
And yes, you said verbatim "stroke has nothing to do with torque", so don't backpedal now...
03-13-11, 03:28 PM
#161
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I never said it was that easy champ. You stated that stroke had nothing to do with torque. I was simply stating that assuming ALL OTHER VARIABLES are equal, the motor with the longer stroke will produce more torque. Again, argue all you want, but you're arguing with physics at this point, not me.
You stated that stroke had nothing to do with torque. I was simply stating that assuming ALL OTHER VARIABLES are equal, the motor with the longer stroke will produce more torque. Again, argue all you want, but you're arguing with physics at this point, not me. 
Why don´t you read Peejay´s post? He said exactly same thing as me. I admit that in better manner
I don´t want to clutter this thread more than already is. What I´m saying is right, simple and can be backed up by physics.
Actually, You are the one who gave bad examples and misunderstood basics of fair comparison
If you can´t back up claim, that longer stroke increases specific torque on fixed displacement, please do not post, you are the one who argue with physics, not with me
03-13-11, 03:49 PM
#162
LOL...Kid, you have no idea how many physics courses I've taken. I'm an engineer. Now kindly go read some physics books and gain a better understanding of how internal combustion engines work, k? You were the one arguing that stroke has nothing to do with torque, then went off on another tangent to mask your previously invalid argument. Clearly you think you're right beyond all else, and no one here's going to be able to tell you otherwise.
03-13-11, 04:08 PM
#163
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So when you are engineer with so many physics courses, You sure can back up what you are saying? I´m not ignorant like you, so bless me with your knowledge
03-13-11, 05:55 PM
#165
Simply put, I don't feed trolls like you. I have nothing to prove, and already knew that was the exact, lame response you were going to come back with before you even responded. I could write a book explaining how an internal combustion engine produces torque, along with the laws of physics. Would I do it to prove you wrong? Nah, not worth my time. Now, as cabaynes suggested, let's keep this on topic.
Now, as cabaynes suggested, let's keep this on topic.
03-13-11, 06:14 PM
#166
Its cool guys I am never one to miss a chance to learn more information. I did go back to the dyno today, and got to stretch the FD's legs a little. Did all types of video, and
tested 4 setups individually. Here is a overview, going off memory. Dyno charts and vids coming next!
-First I streamlined the semi p-port manifold some, just making the best of what was there. Did some pulls, and it did indeed help and made 434rwhp. Biggest surprise is 250 rwtq! excellent.
-Next I swapped in race plugs, due to so many members telling me that 10hp or more can be gained. I was a doubting tomas, but bought some anyway to test back to back. Result? 436rwhp. 2 horsepower for $190??? Yeah looks like this goes into the "busted" category.
-Then we swapped just upper intake manifolds, and ran the stock intake with semi p-ports. Shocking result #1 of the day, it make 420rwhp. Looks like semi p-ports are totally amazing in flow.
-Then I removed the gasket from the lower intake, and swapped in a stock one without semi p-port holes. This blocks off the semi p-ports at the flange. Then did some STREETPORT only pulls.
- Shocking result #2 of the day, the stock intake/streetport made 350rwhp!! Amazing!!!
Last time I tested the stock intake the electromotive software had a glitch which was not sparking leading #3. So Leading ignition missing on one rotor makes for a 28rwhp loss. In case anyone wondered lol
- Lastly we then swapped on the sheet metal intake/ streetport only. Kinda disappointing result, hit 355rwhp. It did lean out a bunch, and didnt have time to re-tune. I think it would have made 360-365. Only a 10-15 hp gain. But not bad!
I am never one to miss a chance to learn more information. I did go back to the dyno today, and got to stretch the FD's legs a little. Did all types of video, and tested 4 setups individually. Here is a overview, going off memory. Dyno charts and vids coming next!
-First I streamlined the semi p-port manifold some, just making the best of what was there. Did some pulls, and it did indeed help and made 434rwhp. Biggest surprise is 250 rwtq! excellent.
-Next I swapped in race plugs, due to so many members telling me that 10hp or more can be gained. I was a doubting tomas, but bought some anyway to test back to back. Result? 436rwhp. 2 horsepower for $190??? Yeah looks like this goes into the "busted" category.
-Then we swapped just upper intake manifolds, and ran the stock intake with semi p-ports. Shocking result #1 of the day, it make 420rwhp. Looks like semi p-ports are totally amazing in flow.
-Then I removed the gasket from the lower intake, and swapped in a stock one without semi p-port holes. This blocks off the semi p-ports at the flange. Then did some STREETPORT only pulls.
- Shocking result #2 of the day, the stock intake/streetport made 350rwhp!! Amazing!!!
Last time I tested the stock intake the electromotive software had a glitch which was not sparking leading #3. So Leading ignition missing on one rotor makes for a 28rwhp loss. In case anyone wondered lol
- Lastly we then swapped on the sheet metal intake/ streetport only. Kinda disappointing result, hit 355rwhp. It did lean out a bunch, and didnt have time to re-tune. I think it would have made 360-365. Only a 10-15 hp gain. But not bad!
03-13-11, 06:48 PM
#168
Stroke is primary in deciding the propensity for torque production of an engine package at a given rpm band. Timing, cams, ignition, turbos, heads, et al only work to determine the efficiency of the package at any moment.
So, lets stop arguing about something that isn't up for argument. This is physics.
Force x Lever Length = Torque.
always has been, always will be. longer lever = more torque.
03-13-11, 08:54 PM
#170
Old [Sch|F]ool
So, lets stop arguing about something that isn't up for argument. This is physics.
Now, what really bakes the noodle, is imagining how the pressure is acting on the rotor. At least a piston engine is pushing on one surface that all moves in the same direction and speed. When combustion happens in a rotary, it's pushing forwards on some parts of the rotor, neutral at other parts, and backwards at the rest... Suddenly I want to experiment with late-trailing spark plugs.
And the asymmetrical depressions in late 12A rotors suddenly make a lot more sense. I know what I'm doing to the next 13B I put together.
03-13-11, 10:14 PM
#171
Different strokes for different folks 
So here are some charts from the dyno. I will post much more detailed runs in a new thread, for all the techno geeks like me
The peak runs of the day, 435.8 rwhp and 251.8 rwtq. This is the same setup, just with smoothed p-port manifold. Now its time to rip it all off and put on the new slide throttles! Once I get it built that is. lol.
And here is a real result that was unexpected. 350 rwhp, and 240rwtq on totally stock intake (2" removed from lower, as per our 20b conversion kit) and streeport only. If you guys are not sold on shortening the stock intake, hopefully you are by now.
And here is the run of streetport only vs. Semi p-port. On the streetport run the p-ports were capped off at the flange just like I had done for so many years. As you can see, torque really doesnt suffer much down low.
So here are some charts from the dyno. I will post much more detailed runs in a new thread, for all the techno geeks like me
The peak runs of the day, 435.8 rwhp and 251.8 rwtq. This is the same setup, just with smoothed p-port manifold. Now its time to rip it all off and put on the new slide throttles! Once I get it built that is. lol.
And here is a real result that was unexpected. 350 rwhp, and 240rwtq on totally stock intake (2" removed from lower, as per our 20b conversion kit) and streeport only. If you guys are not sold on shortening the stock intake, hopefully you are by now.
And here is the run of streetport only vs. Semi p-port. On the streetport run the p-ports were capped off at the flange just like I had done for so many years. As you can see, torque really doesnt suffer much down low.
03-14-11, 01:32 PM
#172
An equal volume of combustion creates and equal amount of force, causing equal expansion in the only direction possible: down.
The size of the piston face has no bearing on torque production. It's simply a matter of how much force the explosion created, and how long the stroke is to determine the amount of torque.
Everything else is just VE.
03-14-11, 01:41 PM
#173
I promise you that whether you're pushing on a table or a stool, it makes no difference in how much force is being applied. So long as they were at the end of an equal lever arm, the torque would be the same.
An equal volume of combustion creates and equal amount of force, causing equal expansion in the only direction possible: down.
The size of the piston face has no bearing on torque production. It's simply a matter of how much force the explosion created, and how long the stroke is to determine the amount of torque.
Everything else is just VE.
An equal volume of combustion creates and equal amount of force, causing equal expansion in the only direction possible: down.
The size of the piston face has no bearing on torque production. It's simply a matter of how much force the explosion created, and how long the stroke is to determine the amount of torque.
Everything else is just VE.
You, sir, get a standing ovation.
I suppose it could be argued that using the equation F=ma, a piston with a larger surface area would have more mass (at least in a piston engine). However, more mass would also lead to higher inertia, and thus a heavier/more massive piston would not undergo the same acceleration from combustion pressure as a lighter/less massive piston. Would the force be EXACTLY the same when comparing a larger piston to a smaller piston? More than likely not, but we would never know unless we could measure the force of acceleration which acts on the larger piston vs. the smaller piston. Inertia will without a doubt cause the pistons to resist the change in speed, and would have a greater effect on the more massive piston. Nevertheless, the point is that if the force produced was the same, the engine with the longer stroke would produce more torque.
03-14-11, 08:15 PM
#174
For the OP: again, sweet ride you have there. Not many of them around... real special car dude.
03-14-11, 11:28 PM
#175
Hey Logan, when you put the stock intake gasket on, sealing the semi-pp's right at the housings, did you notice any significant improvement in low-end power/torque over the semi-pp's open? Did it behave strictly like a street-ported engine? Great job on more testing!!
So in other news, took a friend around the block in the FD. Shifting from 2nd gear into 3rd gear.... heard a loud noise from the rear end area. I was super lucky and coasted right back to the garage. Broke the torsen case, and the diff shattered! Keep in mind that I have never launched my car from a stop, or drag raced it. Here is the carnage
