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Agreed, if this in fact is the case, how many other customer cars are out there that are ticking timebombs. I know I would want to know if my car had a very high chance of going up in flames. This is also another example of why I am the only one that works on my cars.
Any "professional" mechanic using heater hose on a fuel injection system should be considered fraud. I knew better than that when I was working on my FC at 20 years old...
Ultimately, its tied to the subframes, which are tied to the chassis....
Isolate NVH, tie the power plant and the diff together so the chassis doesn't see these twisting forces, it's applied directly to where the suspension mounts instead, then directed into the ground. The chassis instead sees a fraction of these forces. It's similar to a body-on-frame from an engineering perspective, with the drivetrain as a stressed member of the frame. The Miatas still use PPFs, so it's not simply a dated design.
Do they really fail on stock cars? Sounds like a great idea, with a part that is weak (at least, past stock power / grip levels).
How much power are you running with the solid mounts and no PPF? If anything, the solid mounts would increase chassis stress so you'd see more of an effect I'd imagine. Sounds like this isn't a concern, so unless someone has evidence of harm, I guess there's not much point in exploring it further.
Isolate NVH, tie the power plant and the diff together so the chassis doesn't see these twisting forces, it's applied directly to where the suspension mounts instead, then directed into the ground. The chassis instead sees a fraction of these forces. It's similar body-on-frame from an engineering perspective, with the drivetrain as a stressed member of the frame. The Miatas still use PPFs, so it's not simply a dated design.
Do they really fail on stock cars? Sounds like a great idea, with a part that is weak (at least, past stock power / grip levels).
How much power are you running with the solid mounts and no PPF? If anything, the solid mounts would increase chassis stress so you'd see more of an effect I'd imagine. Sounds like this isn't a concern, so unless someone has evidence of harm, I guess there's not much point in exploring it further.
Maybe not, but stock cars don't exist anymore. Even a "bone stock" car is going to have tires that are twice as good as the ones it came from the factory with, just because of how much tire tech has advanced in 30 years.
Just to clarify, I have a PPF. I meant I just haven't broken mine yet.
I think PPFs were failing more in the drag racing days, when everyone was launching car hard with additional power. I don't know if I've ever really done that, and my PPF is fine.
Has anyone had chassis flex issues removing the PPF using just the braces? This would change the load path from the subframes. With the PPF, both front and rear subframes see the same forces. Without the PPF, those forces are separate and rely on the chassis of the car to carry the twisting load differences between them. Hope I'm explaining this clearly.
Removing the PPF will have no real (let alone noticeable) amount of flex to the chassis. There isn't much additional force transmitted into the chassis for the new front diff mount, and some load is taken off the engine mounts and transferred into the center crossmember below the transmission.
Originally Posted by Valkyrie
Ultimately, why did Mazda even tie the drivetrain together this way? Clearly it wasn't that good of an idea, given how frequently PPFs crack and fail. A number of shops in Japan offered reinforced PPFs back in the day. A few still do. Kind of wish I held on to my spare instead of selling it for peanuts...
I kind of doubt that that it would have that much of an effect on chassis flex.
Ultimately, its tied to the subframes, which are tied to the chassis...
Of course, my cars drivetrain mounts are all solid aluminum, so maybe that's why I haven't had many issues...
It's fine for stock power levels, but for increased power, this design is a challenge and specifically was not intended to handle 2X (or more) the power.
I have my original PPF for sale if anyone wants it.
I have my stock tires, with a couple of thousand miles on them (but they have been sitting in the garage for decades now) :-)
Originally Posted by Valkyrie
Maybe not, but stock cars don't exist anymore. Even a "bone stock" car is going to have tires that are twice as good as the ones it came from the factory with, just because of how much tire tech has advanced in 30 years.
Just to clarify, I have a PPF. I meant I just haven't broken mine yet.
The ghost of Paul Walker is telling you to never put those on your FD again...
Yep, that's what i was implying with the smiley - not usable. But I have them. Might be of interest if i ever sell the car later on and these become something for the survivor class at the high-end concours events. Put them on and trailer it to a show where it sits.
Looking back at archives, the PPF only weighs 20-21 pounds, so I don't think you can realize a 20lb savings by using the Banzai/Sikky brace combo. It's possible that if you're already running the Banzai brace, you could claw back a little weight by removing the PPF in favor of the Sikky brace, but I can't image that'll be any more than 10lbs.
I would think the PPF would have to weight more like 35-40lbs to save 20 with those mods.
Yep, that's what i was implying with the smiley - not usable. But I have them. Might be of interest if i ever sell the car later on and these become something for the survivor class at the high-end concours events. Put them on and trailer it to a show where it sits.
Boooo. Use them for low-speed drifting practice!
I should probably take my FD to Ebisu's wet skid pad once in an while to practice drifting... You can only learn so much from doing fast laps a few times a year.
Project FD RX7 Restomod: Part 12 - Rotor Lightening, WPC and CTP Cryo Treatment
To kick off our engine build, we CNC-lightened the rotors of our 13B REW before shipping them off to be cryogenically frozen by CTP Cryogenics to improve strength and durability then finished off with WPC treatment to reduce friction, wear, and heat.
Is there any balancing involved to ensure they stay symmetrical after the machining? Not sure how that would be done other than similar to corner weighing with a scale under each apex. Just thinking out loud / bored.
Is there any balancing involved to ensure they stay symmetrical after the machining? Not sure how that would be done other than similar to corner weighing with a scale under each apex. Just thinking out loud / bored.
In the article it mentions that balancing all 3 sides of the rotor isn't crucial and almost no one does it. Also the weight of oil sloshing around in the rotor is greater than the difference in weight of each lobe/"apex". Decades of experience from various engine builders have shown that lighter rotors that are similar in weight and balanced properly to the counterweights has been more beneficial than not.
Project FD RX7 Restomod: Part 13 - Porting the 13B REW
Increasing airflow and power can be achieved through different types of porting on a rotary engine. Each type has their own benefits and drawbacks, but there is a lot of variability in how a given port job is done. We are going to use a Bridgeport and Semi Peripheral Port job on our turbocharged 13B REW biased towards minimizing increased overlap, which will give us a wide powerband that extends well above the stock 8,000rpm redline.
Man I swear I haven't been here in years but you all still cry the same. Can you not criticize everything the guy does and let him build his car without trying to assert your dominance? Sheesh
Looking back at archives, the PPF only weighs 20-21 pounds, so I don't think you can realize a 20lb savings by using the Banzai/Sikky brace combo. It's possible that if you're already running the Banzai brace, you could claw back a little weight by removing the PPF in favor of the Sikky brace, but I can't image that'll be any more than 10lbs.
I would think the PPF would have to weight more like 35-40lbs to save 20 with those mods.
Thank you for the clarification. The glare from my scale made it look like 33lbs (including the removed nuts and aluminum chassis brace that was replaced by the Banzai trans brace/mount) vs 23lbs. So the weight reduction was slightly over 10lbs, not 20lbs.
Originally Posted by Sm1nts2escape
Man I swear I haven't been here in years but you all still cry the same. Can you not criticize everything the guy does and let him build his car without trying to assert your dominance? Sheesh
It's unfortunate that there's a lot of people in the aftermarket scene (across all brands) who constantly need to prove how smart they are by putting down others, rather than having the confidence in their ability and knowledge to either not care what someone else is doing, or to provide advice based off their experience.
IMO, real "car guys" appreciate what other people do rather than put them down. I'm not into the "stance" crowd and their is a lot wrong with how modifying cars in that way affect ride quality, performance, and safety; but to each their own and people enjoy and prefer different things. That doesn't make them "wrong" unless their goal is to set lap times or drive their stanced cars aggressively.
My articles are to share and discuss my journey, developments, and modifications to my street/track car.
Last edited by Billj747; Feb 14, 2024 at 09:29 AM.
very interesting stuff. i will have to make some time to read all of the installations, but what i have read so far is great and has even given me some clarity on how to tackle some issues i'm having with my own car.
at any rate, i've known about the WPC treatment for a while now and have been curious how they will work on a rotary, so i'm definitely here to see what results you get from it.
I really appreciate these articles. I like the mix of rotary specific and general performance information, and it's kind of cool to see you guys coming at this stuff from another angle and with fresh eyes. I learn a lot from each article. I'm sure they're a lot of work to write, so thank you!
very interesting stuff. i will have to make some time to read all of the installations, but what i have read so far is great and has even given me some clarity on how to tackle some issues i'm having with my own car.
at any rate, i've known about the WPC treatment for a while now and have been curious how they will work on a rotary, so i'm definitely here to see what results you get from it.
good luck.
Thank you for the comments I am also eager to see how WPC works in a rotary application and if there's the same benefit as I saw in piston engines. Just like anything, some components may yield massive returns while others might not be worth the time and effort. Time will tell.
Originally Posted by sunkat
I really appreciate these articles. I like the mix of rotary specific and general performance information, and it's kind of cool to see you guys coming at this stuff from another angle and with fresh eyes. I learn a lot from each article. I'm sure they're a lot of work to write, so thank you!
Thank you for the feedback and for following. Feel free to shoot any questions on this thread, which is why I have posted it here, to create discussions
Project FD RX7 Restomod: Part 14 - When to Upgrade the Differential
The FD RX-7 has many drivetrain limitations that start to fail as power approaches double the factory output. Upgrading to a Ford Explorer 8.8” differential actually makes a lot of sense, even financially, at a far lower power level than most RX-7 owners realize.
Check out this article where we point out the parts cost of upgrading to the Explorer 8.8" (after selling the stock parts) is similar to the price of upgrading the stock diff with an aftermarket LSD and adding a brace.
Project FD RX7 Restomod: Part 14 - When to Upgrade the Differential
The FD RX-7 has many drivetrain limitations that start to fail as power approaches double the factory output. Upgrading to a Ford Explorer 8.8” differential actually makes a lot of sense, even financially, at a far lower power level than most RX-7 owners realize.
Check out this article where we point out the parts cost of upgrading to the Explorer 8.8" (after selling the stock parts) is similar to the price of upgrading the stock diff with an aftermarket LSD and adding a brace.
Love it! Nice write up @Billj747
Crazy timing.... I just finished my Ronin 8.8 swap with Grande hubs/axles.
It should be able to take pretty much anything I throw at now.
Mine starts about page 14 in my build thread...
@Billj747