Non-turbo 428rwhp FD build up and history
01-16-11, 06:32 PM
#77
You could attempt some sort of variable geometry intake...has worked so well for the manufacturers for n/a power delivery. Even the R26B used it...but a bit complicated.
A vacuum/butterfly actuation setup would work best...it's just designing and casting the manifold that are going to suck :[
A vacuum/butterfly actuation setup would work best...it's just designing and casting the manifold that are going to suck :[
01-16-11, 06:36 PM
#78
You could attempt some sort of variable geometry intake...has worked so well for the manufacturers for n/a power delivery. Even the R26B used it...but a bit complicated.
A vacuum/butterfly actuation setup would work best...it's just designing and casting the manifold that are going to suck :[
A vacuum/butterfly actuation setup would work best...it's just designing and casting the manifold that are going to suck :[
01-16-11, 07:32 PM
#79
Since before this car was even started on, I wanted to use the Ferrari F40 for the power/weight benchmark. Now its been exceeded. In the real world is different than on paper though!
I thought it would be fun to look up and post several popular well known factory powerhouse engines. Here is the first- the world famous F40 ferrari. Only chart I could find. The red lines are a different car, yellow lines F40. You can see the outstanding boost response and power down low the F40 has. Enough to take many cars by surprise.
Next up is a excellent comparison. The Ferrari F430. Being a full half liter larger, its is interesting to compare to my 3-rotor. Naturally aspirated, and 4.3 liters, its a prime example of well made power. This chart I think is stock vs modified. I used the modified one, why not.
2010 Corvette Z06. Now this one I was nervous to even look up. Sure the n/a 20b in my lightweight Rx-7 will beat it. But engine vs engine...... what a scary challenge! Coming in at a massive 7 liters, its a full 3.1 liters larger! Look at the torque! Even a beginner driver cant miss. ANYWHERE in the rpm large power is there However once both are in the effective powerbands, the micro 20b is only at a 22 horsepower disadvantage.
Last one I found is my favorite. The Porsche 996 GT3. The best of the best in a 3.8 liter n/a package. With 435 horsepower and 317 ft-lbs, it produces a staggering 83 ft-lbs per liter! Very Very efficient engine. It will be my new personal goal of torque This example has had full headers/exhaust/intake and computer upgrades. First line is without computer re-flash. Second is with.
I thought it would be fun to look up and post several popular well known factory powerhouse engines. Here is the first- the world famous F40 ferrari. Only chart I could find. The red lines are a different car, yellow lines F40. You can see the outstanding boost response and power down low the F40 has. Enough to take many cars by surprise.
Next up is a excellent comparison. The Ferrari F430. Being a full half liter larger, its is interesting to compare to my 3-rotor. Naturally aspirated, and 4.3 liters, its a prime example of well made power. This chart I think is stock vs modified. I used the modified one, why not.
2010 Corvette Z06. Now this one I was nervous to even look up. Sure the n/a 20b in my lightweight Rx-7 will beat it. But engine vs engine...... what a scary challenge! Coming in at a massive 7 liters, its a full 3.1 liters larger! Look at the torque! Even a beginner driver cant miss. ANYWHERE in the rpm large power is there
However once both are in the effective powerbands, the micro 20b is only at a 22 horsepower disadvantage. Last one I found is my favorite. The Porsche 996 GT3. The best of the best in a 3.8 liter n/a package. With 435 horsepower and 317 ft-lbs, it produces a staggering 83 ft-lbs per liter! Very Very efficient engine. It will be my new personal goal of torque
This example has had full headers/exhaust/intake and computer upgrades. First line is without computer re-flash. Second is with.
01-16-11, 08:39 PM
#80
I think the 996 GT3 may be THE best comparison and target, as you suggest. If you are considering the 20b a 3.9 liter motor, yours is making 62 foot pounds versus the GT3 making 71 foot pounds. Also, you have a much smoother torque curve and, because you keep making torque way after the GT3 runs out of air after about 7500 rpm.
Gordon
Gordon
01-16-11, 10:34 PM
#83
Yes, all my newest plans involve changes to the intake, ignition, fuel system, and exhaust. Tuning the air/fuel and timing is always optimized each time a physical change is made. So that is pretty standard knowledge from experience.
All these planned changes are mostly just for semi p-ports. I believe a lot of gains are still left to be found. Simply because they change the rules so much, its a whole new ballgame.
01-16-11, 10:42 PM
#84
This is complicated to explain. I have the dyno chart of with them closed vs open. The lower end torque was only very slightly higher (5-8ftlbs) and only in a few spots. Once the engine went past 6500 rpm the torque tanked. Basically the volume of air between the semi p-port ITB and engine block creates turbulance at high rpm. So in this instance, it was no different to just open them all at the same time. I have some new plans to eliminate this volume of air, and then I will stage them at 6-7k to come online.
01-18-11, 02:03 AM
#85
Environmentally-Hostile
Just read through this whole thread. This is probably my favorite RX7 now. I find it very telling how similar the power AND torque band is to a Porsche GT3. I'm trying to imagine how this car must feel like to drive. I imagine the feeling is similar to my SE (as in the pull is basically the same anywhere from 3k-redline) but just a hell of a lot more of it. I'm very anxious to see how clean you can get that torque curve to become with more tuning. Never seen a rotary dyno that flat before. Keep up the good work! N/A FTW!!
01-18-11, 03:30 AM
#86
i just have to say once again, i love your work. you've always had my attention. the car is amazing!
from the first time i got a real good look at a functioning semi-peripheral, i knew that they were very, very special engines. for now, i've fallen by the wayside, but it does my heart good to see the developments and strides you're making for semi-peripherals, particularly the street aspects you seemed to have shown. keep doing your thing!
+1
from the first time i got a real good look at a functioning semi-peripheral, i knew that they were very, very special engines. for now, i've fallen by the wayside, but it does my heart good to see the developments and strides you're making for semi-peripherals, particularly the street aspects you seemed to have shown. keep doing your thing!
Back in 1997-98 people like Cam Worth and Ari and Peter Farrell were coming out with innovative stuff that made more power and better handling. All those guys are basically gone, retired, or focused on other things. Today, Logan is one of the leading guys doing that kind of interesting stuff and he is producing some really hot cars with new and interesting technology.
01-18-11, 11:34 AM
#87
Just read through this whole thread. This is probably my favorite RX7 now. I find it very telling how similar the power AND torque band is to a Porsche GT3. I'm trying to imagine how this car must feel like to drive. I imagine the feeling is similar to my SE (as in the pull is basically the same anywhere from 3k-redline) but just a hell of a lot more of it. I'm very anxious to see how clean you can get that torque curve to become with more tuning. Never seen a rotary dyno that flat before. Keep up the good work! N/A FTW!!
i just have to say once again, i love your work. you've always had my attention. the car is amazing!
from the first time i got a real good look at a functioning semi-peripheral, i knew that they were very, very special engines. for now, i've fallen by the wayside, but it does my heart good to see the developments and strides you're making for semi-peripherals, particularly the street aspects you seemed to have shown. keep doing your thing!
+1
from the first time i got a real good look at a functioning semi-peripheral, i knew that they were very, very special engines. for now, i've fallen by the wayside, but it does my heart good to see the developments and strides you're making for semi-peripherals, particularly the street aspects you seemed to have shown. keep doing your thing!
+1
01-18-11, 12:33 PM
#88
It would be really educational to compare charts of available wheel torque at vehicle speeds in various gears.
This will show how much torque a high rpm engine puts down because you are able to use the torque multiplication of a lower gear ratio at the same vehicle speed as a lower rpm engine.
This will show how much torque a high rpm engine puts down because you are able to use the torque multiplication of a lower gear ratio at the same vehicle speed as a lower rpm engine.
01-18-11, 04:15 PM
#89
It would be really educational to compare charts of available wheel torque at vehicle speeds in various gears.
This will show how much torque a high rpm engine puts down because you are able to use the torque multiplication of a lower gear ratio at the same vehicle speed as a lower rpm engine.
This will show how much torque a high rpm engine puts down because you are able to use the torque multiplication of a lower gear ratio at the same vehicle speed as a lower rpm engine.
01-18-11, 10:08 PM
#90
Environmentally-Hostile
I would actually be interested to see a plot of g-force against RPM and see how it relates to torque and horsepower. Then compare that to other cars. This would be the best gauge of the 'how it feels' factor.
01-22-11, 01:00 AM
#93
Environmentally-Hostile
Could you make an in-car video of what this beast sounds like from the cabin?
Also, I've noticed 2 rotors tend to sound best when they have a 'true dual' system where each rotor has a completely separate exhaust pipe. Similarly, I think the 4 rotor sounds better when it has a 4-2 header instead of the 4-2-1 header (such as on the 787B) I just wonder if anyone has done a 'true triple' exhaust for the 20b?
Also, I've noticed 2 rotors tend to sound best when they have a 'true dual' system where each rotor has a completely separate exhaust pipe. Similarly, I think the 4 rotor sounds better when it has a 4-2 header instead of the 4-2-1 header (such as on the 787B) I just wonder if anyone has done a 'true triple' exhaust for the 20b?
01-22-11, 11:47 AM
#95
Group buy? We could probably get 5 orders easy. Do you have enough room in your shop to do 5 builds in parallel?
Looking forward to seeing your car and shooting the breeze with you at Sevenstock in September. I think Gordon is planning to come and ship his car as well. Are you guys travelling together??
This in kinda my dream build. Yes, much more up front cost, but as Gordon pointed out, much less hassles and worry. Unlike Gordon though, I WOULD like the lumpy idle
Looking forward to seeing your car and shooting the breeze with you at Sevenstock in September. I think Gordon is planning to come and ship his car as well. Are you guys travelling together??
This in kinda my dream build. Yes, much more up front cost, but as Gordon pointed out, much less hassles and worry. Unlike Gordon though, I WOULD like the lumpy idle
01-22-11, 02:41 PM
#96
Could you make an in-car video of what this beast sounds like from the cabin?
Also, I've noticed 2 rotors tend to sound best when they have a 'true dual' system where each rotor has a completely separate exhaust pipe. Similarly, I think the 4 rotor sounds better when it has a 4-2 header instead of the 4-2-1 header (such as on the 787B) I just wonder if anyone has done a 'true triple' exhaust for the 20b?
Also, I've noticed 2 rotors tend to sound best when they have a 'true dual' system where each rotor has a completely separate exhaust pipe. Similarly, I think the 4 rotor sounds better when it has a 4-2 header instead of the 4-2-1 header (such as on the 787B) I just wonder if anyone has done a 'true triple' exhaust for the 20b?
Honestly you would have to hear some of the n/a 2 rotors we've built, they might change your mind about true dual vs single. True triple would not only be heavy and hard to place mufflers, it also would lose massive amounts of power. :/Thank You
I still havent came even close to getting used to it. I can get used to a 650rwhp turbo 20b in a few days though. Strange for sure. Group buy? We could probably get 5 orders easy. Do you have enough room in your shop to do 5 builds in parallel?
Looking forward to seeing your car and shooting the breeze with you at Sevenstock in September. I think Gordon is planning to come and ship his car as well. Are you guys travelling together??
This in kinda my dream build. Yes, much more up front cost, but as Gordon pointed out, much less hassles and worry. Unlike Gordon though, I WOULD like the lumpy idle
Looking forward to seeing your car and shooting the breeze with you at Sevenstock in September. I think Gordon is planning to come and ship his car as well. Are you guys travelling together??
This in kinda my dream build. Yes, much more up front cost, but as Gordon pointed out, much less hassles and worry. Unlike Gordon though, I WOULD like the lumpy idle
We have plenty of room to do a 5 car parallel build. Get 5 guys together and I am sure we can make one heck of a group buy
Yeah, I think every man has to exercise both sides of his personality. The civil and controlled, but also the slighly barbaric. Answer is to build two cars. Just as you are doing!
Last edited by GtoRx7.; 01-22-11 at 02:46 PM.
01-28-11, 12:22 AM
#100
Some Calculations on Acceleration
I was asked by Logan to put together some plots that would compare the rate of acceleration vs. road speed in each gear. He sourced the dynamometer charts (as shown earlier) as well as some preliminary aerodynamic information.
I put together this spreadsheet that calculates several things based on the following inputs:
1) Tire diameter
2) Transmission and final drive ratios
3) Weight of the vehicle
4) Coefficient of drag
5) Frontal area of the vehicle
6) The density of the fluid being traveled through (air)
7) Torque at a specific RPM
The following outputs are calculated (in each gear):
1) Horsepower (not sensitive to current gear)
2) Wheel torque
3) Forward thrusting force (accelerating force)
4) Rate of forward acceleration
5) Forward accelerating Gs
6) Aerodynamic drag force
7) Vehicle speed
The spreadsheet is attached so that people may see the sources. It is the attached *.zip file.
PLOTS:
I put together this spreadsheet that calculates several things based on the following inputs:
1) Tire diameter
2) Transmission and final drive ratios
3) Weight of the vehicle
4) Coefficient of drag
5) Frontal area of the vehicle
6) The density of the fluid being traveled through (air)
7) Torque at a specific RPM
The following outputs are calculated (in each gear):
1) Horsepower (not sensitive to current gear)
2) Wheel torque
3) Forward thrusting force (accelerating force)
4) Rate of forward acceleration
5) Forward accelerating Gs
6) Aerodynamic drag force
7) Vehicle speed
The spreadsheet is attached so that people may see the sources. It is the attached *.zip file.
PLOTS: