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Old 10-26-2011, 03:36 PM   #141
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The exhaust is being mounted >to< the PPF, not next to it
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Old 10-26-2011, 04:02 PM   #142
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It is going to rattle and resonate against the ppf. Of course that is just my opinion.
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Old 10-26-2011, 04:12 PM   #143
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I don't understand how it could rattle against the PPF if it is solidly mounted to it. We'll see, I guess!
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Old 10-26-2011, 04:24 PM   #144
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Harmonics, it is going to make noise, trust me. Have you ever seen an exhaust hard mounted to anything in a car? But as you say, we will see. Another thought, you are way over thinking the cooling in the car. I would leave the hood stock, get an appropriate undertray on the car, and see how the engine runs before cutting up the stock hood. You have mentioned being on a budget, so why spend money modifying a hood that does not to be modified. Remember, I ran my car at 6000 feet and had no cooling issues when it was NA.

Last edited by hingstonwm; 10-26-2011 at 05:10 PM.
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Old 10-26-2011, 04:33 PM   #145
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Yeah I am slightly concerned about the PPF becoming a very large tuning fork. But if it does, it'll be changed.
Re. the cooling... I agree that any sort of rear ducting, let alone a sealed vent through a bloody great hole in the bonnet, is unnecessary. But I'm doing it for the same reason as I'm doing the flat floor w/diffuser - due to other design aspects of this car, I have the space to do it, so why the hell not. I can certainly be sure I won't have cooling issues on track (the car will probably morph into a hillclimb car in the future), and the teeny reduction in front and rear lift might just make the car a fraction more stable at high speed.
Re. budget - the budget is increasing because I'm working harder and selling my life away. So it's not the watching-every-penny exercise it was at the very start. Next stage is selling myself. Offers on a postcard folks.
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Old 10-26-2011, 04:50 PM   #146
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How much are you selling yourself for?
I heard hustler was looking for a replacement sex slave.
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Old 10-26-2011, 04:54 PM   #147
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PM'd.





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Old 10-26-2011, 05:24 PM   #148
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Quote:
Originally Posted by owenwilliams View Post
Sean, both silencers sit above the level of the frame rails.
From the pictures I can see the mufflers are above the frame rails I would be more concerened of where it exits to the side. It looks like the pipe will be under the frame rail unless you are notching the frame or exiting after it fades back into the body. I cannot see very well. I just know if you plan on tracking the car most likely it will be lower than stock and absolutely any thing below the frame rail will scrape. I have tried to cheat stuff below it but it never works for me.
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Old 10-26-2011, 05:34 PM   #149
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Notching the frame rail? Blasphemy !
There's a bit of non-structural 'excess' outer body panel that sticks out past the end of the main body section, well after the frame rail has faded back into the body. Basically, the bit right by the rear wheel. If anybody out there cares, it's obvious if you look under the car. This section is being cut out. The 3" outlet fits nicely between this and the rear tyre. The silencer sits in the handy space just in from here. Or it will do, once some lines have been rearranged
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Old 10-27-2011, 03:00 PM   #150
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Work was rained off again today, so I got back early and got over to the shop to have another chat and take a couple more photos. Exactly contrary to my post above, Quent decided to take some of the sill out to give the exhaust tip some more space. The hole in the sill will be opened up more, then double-skinned and made stronger than it was to start with, so I think this was definitely the right decision.

I mentioned the concerns some of you have with resonance of the PPF. Quent isn't too worried about this due to the PPF being rubber mounted, and the exhaust being rubber mounted to the PPF. So the potential for it to turn into a tuning fork is minimal. Of course, he agreed that if resonance turns out to be a problem, it will be changed.

Hingston, I got a couple of photos of the PPF to gearbox mount. They didn't turn out very well, as usual. Also, the mount will be seriously trimmed down in all non essential areas (think FEA) to save weight, so what you see is far from finished, but it is structurally complete. Don't ask me how it works, because frankly I'm not sure. Quent's a (very) qualified engineer though, so I trust him.
Photos in half an hour or so..
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Old 10-27-2011, 04:07 PM   #151
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Photo below shows how the first silencer protrudes into the cabin. Ie, it doesn't protrude into the cabin very much, which is good. The seat is a Profi SPG, same as mine, but black. It was one they had in the shop that they used when they didn't have mine. Mine's red, because red is faster.







Photo below shows ground clearance. Exhaust is above frame rail height, subframe/sump is about an inch below.



Photo below shows initial sill cut.



Photo below shows the silencer just resting on a dynamic variable height organic platform. AKA, a broom.



This is a Cosworth YB that's in for a re-rebuild. Seems the previous builder was a little bit rubbish. Eg, the head gasket is protruding out to one side. Not a good start, huh.



PPF mount 1:



PPF mount 2:



This photo was taken looking up from underneath the front wheels. As you can see, I have enough space in front of this engine to either a) mount that Cosworth YB; or b) build a totally unnecessary but potentially fabulous radiator vent. Begrudgingly, I am choosing option b.

Attached Thumbnails
Just Another F20C build... &lt;Preview&gt;-fqshy.jpg   Just Another F20C build... &lt;Preview&gt;-av7iq.jpg   Just Another F20C build... &lt;Preview&gt;-qxbie.jpg   Just Another F20C build... &lt;Preview&gt;-sgkad.jpg   Just Another F20C build... &lt;Preview&gt;-aoyfv.jpg  

Just Another F20C build... &lt;Preview&gt;-zeqij.jpg   Just Another F20C build... &lt;Preview&gt;-ygzh0.jpg   Just Another F20C build... &lt;Preview&gt;-x5zjd.jpg   Just Another F20C build... &lt;Preview&gt;-9egxx.jpg   Just Another F20C build... &lt;Preview&gt;-y4oa4.jpg  

Just Another F20C build... &lt;Preview&gt;-av7iq.jpg   Just Another F20C build... &lt;Preview&gt;-qxbie.jpg   Just Another F20C build... &lt;Preview&gt;-sgkad.jpg   Just Another F20C build... &lt;Preview&gt;-aoyfv.jpg   Just Another F20C build... &lt;Preview&gt;-zeqij.jpg  

Just Another F20C build... &lt;Preview&gt;-ygzh0.jpg   Just Another F20C build... &lt;Preview&gt;-x5zjd.jpg   Just Another F20C build... &lt;Preview&gt;-9egxx.jpg   Just Another F20C build... &lt;Preview&gt;-y4oa4.jpg  
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Last edited by owenwilliams; 10-27-2011 at 05:31 PM.
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Old 10-27-2011, 04:08 PM   #152
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why are my photos tiny. Damn you new imgur.
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Old 10-27-2011, 05:33 PM   #153
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Photos are now big 'n' blurry, just the way you like 'em.
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Old 10-27-2011, 08:45 PM   #154
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Your photos suck, I can only hope that your builder is taking good pics so you can replace all the blurry shots, you need to invest in a decent digital camera, you can pick one up for under a hundred U.S. On the serious side, I don't think the cut to the rocker is going to cause any strength issues. I don't like the transmission mount, Having anything that hangs below the chassis stiffeners is just asking for them to get ground off. There are way to many Miata's that have crushed stiffeners, but again, time will tell if you will have to revisit the design. Your pics don't really show how the bracket attaches to the transmission. Hopefully, the pics from your builder will be better quality and we will be able to see how things are designed.

Please don't take offense to my view. I understand that each person has their own vision of what their project is going to be; they are all individual works that reflect the owners ideas. Im just voicing my opinion, not bashing your work.
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Old 10-27-2011, 08:49 PM   #155
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Took a closer look at the ppf mount. Interesting design. Is the transmission isolated from vibration, or is is solid mounted to the bracket and cross member?
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Old 10-28-2011, 12:55 AM   #156
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"I don't like the transmission mount, Having anything that hangs below the chassis stiffeners is just asking for them to get ground off."
Explain. Nothing hangs below the chassis stiffeners (frame rails?) except the front subframe, which will have an ali sump guard over it.

"Is the transmission isolated from vibration, or is is solid mounted to the bracket and cross member?"
Would be a bit mental if it was locked solid! There's a rubber block mounted in compression between those two cylindrical braces and the horizontal plate on the gearbox.
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Old 10-28-2011, 03:18 AM   #157
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Quote:
Originally Posted by owenwilliams View Post
"I don't like the transmission mount, Having anything that hangs below the chassis stiffeners is just asking for them to get ground off."
Explain. Nothing hangs below the chassis stiffeners (frame rails?) except the front subframe, which will have an ali sump guard over it.

"Is the transmission isolated from vibration, or is is solid mounted to the bracket and cross member?"
Would be a bit mental if it was locked solid! There's a rubber block mounted in compression between those two cylindrical braces and the horizontal plate on the gearbox.
As I said, you can't see much from your pics, I was asking because I couldn't tell from the pics.

You have never seen a miata with squished chassis stiffeners? I will post up a pic for you.
This is a mild squish, most are much worse. I don't know if you have speed bumps on your side of the pond, but we have them here. I have heard of them being squished by other things as well. Think of the "frame rail" as being your crotch and a speed bump being the top bar on a boys bike that you are to short to touch the ground when off the pedals. Can you picture how, why, things bottom in the middle of the car?

This is not an uncommon occurrence
Attached Thumbnails
Just Another F20C build... &lt;Preview&gt;-framrail.jpg   Just Another F20C build... &lt;Preview&gt;-framrail.jpg  

Last edited by hingstonwm; 10-28-2011 at 03:36 AM.
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Old 10-28-2011, 03:28 AM   #158
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I have seen squished stiffeners, yeah. I haven't scraped mine at all since I've had it, and it'll be at near-standard ride height after the build. I call them frame rails 'cos that's what everyone in the UK calls them, so it avoids confusion with people thinking you're talking about chassis braces.
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Old 10-28-2011, 03:39 AM   #159
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Quote:
Originally Posted by owenwilliams View Post
I call them frame rails 'cos that's what everyone in the UK calls them, so it avoids confusion with people thinking you're talking about chassis braces.
Makes sense.
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Old 10-28-2011, 05:32 AM   #160
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Quote:
Originally Posted by owenwilliams View Post
I have seen squished stiffeners, yeah. I haven't scraped mine at all since I've had it, and it'll be at near-standard ride height after the build. I call them frame rails 'cos that's what everyone in the UK calls them, so it avoids confusion with people thinking you're talking about chassis braces.
Plus you have P5's stainless covers over the top IIRC, so the rails/stiffeners are not going to get squished, well the might but the car would likely be unusable afterwards.
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