Just Another F20C build... <Preview>
09-15-2012, 09:03 PM
#282
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Moar figures:
Old engine: 27 miles per UK gallon
New engine: 30mpg.
Both figures were achieved after a mix of motorway miles, town stuff, and very-spirited-driving stuff.
Mr triple88a - the silver 90deg bend is screwed to the chassis. The intake apparatus (been a while since I've used that word!) can pivot around this point as the engine moves, helped by a little flex in the long silicone pipe. This fixing point doesn't allow it to move up or down, so it can't hit anything.
Old engine: 27 miles per UK gallon
New engine: 30mpg.
Both figures were achieved after a mix of motorway miles, town stuff, and very-spirited-driving stuff.
Mr triple88a - the silver 90deg bend is screwed to the chassis. The intake apparatus (been a while since I've used that word!) can pivot around this point as the engine moves, helped by a little flex in the long silicone pipe. This fixing point doesn't allow it to move up or down, so it can't hit anything.
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09-17-2012, 09:15 AM
#285
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Great to hear about the old engine 
The car's certainly not finished yet. It's going back to the shop in a couple of weeks for a planned final visit, after I've put some more miles on it. List of final tweaks include trimming the interior, heat shielding the trans tunnel, waterproofing everything, reducing the exhaust knocking noises as much as possible, fitting a decent foglight, replacing the windscreen, replacing a sidelight, possibly investigating the steering rack as there's an occassional single knock under hard load, as if something's slipping. Also, trying to get the Unichip to work so I can take it to be tuned.
And finally... Replacing the dampers.
The exhaust bung/silencer is fitted now, and it actually makes the car sound considerably better. Richer, with a better induction/exhaust noise balance.
I'll post another video tonight...
The car's certainly not finished yet. It's going back to the shop in a couple of weeks for a planned final visit, after I've put some more miles on it. List of final tweaks include trimming the interior, heat shielding the trans tunnel, waterproofing everything, reducing the exhaust knocking noises as much as possible, fitting a decent foglight, replacing the windscreen, replacing a sidelight, possibly investigating the steering rack as there's an occassional single knock under hard load, as if something's slipping. Also, trying to get the Unichip to work so I can take it to be tuned.
And finally... Replacing the dampers.
The exhaust bung/silencer is fitted now, and it actually makes the car sound considerably better. Richer, with a better induction/exhaust noise balance.
I'll post another video tonight...
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09-17-2012, 09:27 AM
#287
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Yes. Remember the original dampers that I wanted for this car? That I gave up waiting for? I tried them back to back with the Xidas at the weekend. The Xidas kept the car better tied down over repeated rolling bumps (ie, the other dampers got a bit 'floaty', which is going to be fixed with a little more high-speed rebound damping) and the stiffer spring rates meant the car rolled less. So, the floatyness is being fixed, and the extra roll I don't mind at all. Over small, square edged bumps, the xidas were slightly harsher. Most importantly, and really the only reason I'm changing, is that these other dampers had noticably more travel.
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09-17-2012, 01:01 PM
#289
The reverse rake you have is comical. Hard to imagine the car ever working to it's full potential set up like that. I wish I had know you were planning to run such an odd set up, I would not have recommended the Xida's. You're not running enough preload for the weight and the tall ride height in front is messing with the roll center and roll center axis. It will bottom, steer funny and bounce around up front no matter what band aids. The Xida's work great when used on a Miata with more of a standard track set up.
Bottom line, glad you found your other custom dampers are closer to ideal for your unique application and set up. Looks like fun!
Bottom line, glad you found your other custom dampers are closer to ideal for your unique application and set up. Looks like fun!
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09-17-2012, 01:16 PM
#290
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Not entirely sure how the reverse rake or fractionally altered weight distribution would make much of a difference to the small bump performance or the total travel, which are the two things the others dampers have over the Xidas. The reverse rake situation is simply the best compromise we could find for the travel issues I had. Nothing to do with the lowered sump, or, believe it or not, our ability to set up a car.
The reason these short race dampers don't work for me is because I'm running a high ride height on extremely poor (by American standards) roads. I chose the wrong product for the job. I still believe Xidas are probably the best dampers available for track work and well-surfaced street driving.
The reason these short race dampers don't work for me is because I'm running a high ride height on extremely poor (by American standards) roads. I chose the wrong product for the job. I still believe Xidas are probably the best dampers available for track work and well-surfaced street driving.
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09-17-2012, 02:27 PM
#291
Not entirely sure how the reverse rake or fractionally altered weight distribution would make much of a difference to the small bump performance or the total travel, which are the two things the others dampers have over the Xidas. The reverse rake situation is simply the best compromise we could find for the travel issues I had. Nothing to do with the lowered sump, or, believe it or not, our ability to set up a car.
The reason these short race dampers don't work for me is because I'm running a high ride height on extremely poor (by American standards) roads. I chose the wrong product for the job. I still believe Xidas are probably the best dampers available for track work and well-surfaced street driving.
The reason these short race dampers don't work for me is because I'm running a high ride height on extremely poor (by American standards) roads. I chose the wrong product for the job. I still believe Xidas are probably the best dampers available for track work and well-surfaced street driving.
Full stiff = position #1 / full clockwise to first detent. You'll probably need damping set somewhere between 4-7 all around for your roads.
Try running more preload and taking out all spacers. I think your spacers are fouling things up.
Your roads are what these were built for, not just smooth race tracks.
Edit: Just looked at your order. You have 450/300. You need more spring. I'd suggest 550/350.
Fix that rake. 4.5" front, 4.75" rear. It will work, trust me.
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09-17-2012, 02:56 PM
#292
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I don't have any spacers on the front, and only 10mm spacing at the rear. If I run any more preload at the back, I run out of droop travel.
We've tried most positions on the dial. 6 all around works quite well… 3 seems to work better.
Hitting a single 10" kerb with stiff springs is, I believe, a different situation to the conditions that I'm bottoming under. I'm running the softest springs you supply, and until we raised the rear up another 10mm last week (which all but cured the bottoming, but left me slightly short of droop) the car bottomed over repeated whoops in the road. Ie, where the road has unevenly subsided towards the edge, leaving an absolute roller coaster of tarmac. So in certain situations, especially under power at speed, the car lightens up over one rise, hits the next, lightens up, hits the next, etc. It's a huge test of a car - a new RS6 had the same problem. All at more than 70mph. Winding up the damping to try and control the bounce and keep the car stable made the dampers too firm in most other situations.
Now that I've raised the car with preload, like you've suggested, and nearly cured the bottoming, I'm running out of droop on similar roads. I'll have to take a video some time to show you what I mean.
We've tried most positions on the dial. 6 all around works quite well… 3 seems to work better.
Hitting a single 10" kerb with stiff springs is, I believe, a different situation to the conditions that I'm bottoming under. I'm running the softest springs you supply, and until we raised the rear up another 10mm last week (which all but cured the bottoming, but left me slightly short of droop) the car bottomed over repeated whoops in the road. Ie, where the road has unevenly subsided towards the edge, leaving an absolute roller coaster of tarmac. So in certain situations, especially under power at speed, the car lightens up over one rise, hits the next, lightens up, hits the next, etc. It's a huge test of a car - a new RS6 had the same problem. All at more than 70mph. Winding up the damping to try and control the bounce and keep the car stable made the dampers too firm in most other situations.
Now that I've raised the car with preload, like you've suggested, and nearly cured the bottoming, I'm running out of droop on similar roads. I'll have to take a video some time to show you what I mean.
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09-18-2012, 01:29 AM
#297
The reason the dampers are bottoming is you don't have enough preload. We roll over rounded 10" high kerbs at 100mph and don't bottom. If you're hitting 3-5" rounded bumps at 70mph and bottoming severely, you don't have enough preload and maybe have the damping set too soft.
Full stiff = position #1 / full clockwise to first detent. You'll probably need damping set somewhere between 4-7 all around for your roads.
Try running more preload and taking out all spacers. I think your spacers are fouling things up.
Your roads are what these were built for, not just smooth race tracks.
Edit: Just looked at your order. You have 450/300. You need more spring. I'd suggest 550/350.
Fix that rake. 4.5" front, 4.75" rear. It will work, trust me.
Full stiff = position #1 / full clockwise to first detent. You'll probably need damping set somewhere between 4-7 all around for your roads.
Try running more preload and taking out all spacers. I think your spacers are fouling things up.
Your roads are what these were built for, not just smooth race tracks.
Edit: Just looked at your order. You have 450/300. You need more spring. I'd suggest 550/350.
Fix that rake. 4.5" front, 4.75" rear. It will work, trust me.
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09-18-2012, 03:05 PM
#298
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I just tried running various damping settings on the Xidas again. No luck. As I said in a previous post, I'm basically looking for tarmac rally dampers, except my priority is comfort over speed. Tarmac rally dampers are not short in body and in stroke.
I'm going with longer dampers, more stroke, slightly softer springs. It works.
I will fix the rake as soon as the new dampers go on. The ComedyRake is definitely screwing with the dynamics of my car. Hopefully proper rake with bring the rear of the car a little more into play mid corner too.
Emilio, when I first set up the car, I followed your alignment and rake settings to the letter because I trusted that you know how to set up a car, and I still trust you. What i don't believe is that Xidas were designed for terribly-surfaced road driving. They're race dampers that work very well on the street. If you designed a damper from scratch for extremely bumpy road driving, you can't tell me that you wouldn't use a longer travel design.
I'm going with longer dampers, more stroke, slightly softer springs. It works.
I will fix the rake as soon as the new dampers go on. The ComedyRake is definitely screwing with the dynamics of my car. Hopefully proper rake with bring the rear of the car a little more into play mid corner too.
Emilio, when I first set up the car, I followed your alignment and rake settings to the letter because I trusted that you know how to set up a car, and I still trust you. What i don't believe is that Xidas were designed for terribly-surfaced road driving. They're race dampers that work very well on the street. If you designed a damper from scratch for extremely bumpy road driving, you can't tell me that you wouldn't use a longer travel design.
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