Vorshlag Motorsports Evo X MR Build (STU, TTB, One Lap?)
Mar 13, 2009, 07:54 AM
#77
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I had a really interesting morning I thought I'd share. Late last night Fair and I decided to install a new spring rate package for this weekend's events. Saturday I'm taking the car to a NASA Time Trial, Sunday "the Fairs" will be running the car at an SCCA autocross in STU, a good mix for testing. After seeing all the body roll at Harris Hill we decided to go from 450/550 lb/in to 700/800 rates. Now the car had slight understeer with this first combination, but I attribute some of that to running a skinny, worn out street tire versus the balance AND the nose heavy platform that the Evo is doesn't help. So if we fix the front, it's possible that we fix the issue. We don't like to change the opposite end of the car if we don't have to, I.E. fix what's broken. Most of the time you'd think more spring rate would make that end push more, but sometimes that's not the case. As a side note, we'll be switching to Yokohama AD08s in late April, running AD07s in the meantime. We have always loved Yoks for their R Compound-like turn-in and have had a 1st and 2nd place at Nationals on them too which doesn't hurt.
I drove the car home last night and it definitely felt aggressive to say the least, but not unbearable. I still want a suspension that I can drink a Starbucks in. Call me a snob, but I gotta have my coffee.
I had to meet AJ from Performance Speed Tech (shop at MSR) this morning to deliver a part for a customer. We met in downtown Fort Worth which is 65 miles one way for me. I figured it might be a good test for the new package. I revalved the front slightly and did nothing to the rear. The rear has been working well on soft settings so no need to go up. The front we were running at full stiff so with the increase in rate I upped the rebound valving. North Dallas to Fort Worth is a great test for a suspension. Concrete side streets, new concrete highways, old concrete highways, new asphalt and old, VERY old asphalt highways make up the trip. Not to mention downtown Fort Worth is a disaster of construction. You get a mix of every bump you could ever imagine.
The trip to Fort Worth was comfortable, still aggressive. Definitely not coffee cup worthy. The car was pitching more than I like, and it was pretty obvious the rear of the car was the likely problem since I had them full soft and 6 clicks on the front. After meeting AJ I turned the rears up 5 clicks and drove back to our shop down the same roads. It was a night and day difference! The car was super smooth, obviously stiffly sprung but you could definitely drink your favorite beverage now.
Why do I bring all this up? Aside from the fact that it proves that monotubes can do a great job of controlling high spring rates without beating you up, it comes back to all the chatter we hear about critical damping. Yes, the theory and practice of trying to find the "perfect" suspension via calculations works, it can never beat the actual practical testing on the street. With a simple turn of the knob, I was able to match the front and rear frequencies of the suspension without too much effort. I reached in the trunk, turned two knobs, and was done. I can probably tell you that 700/800 won't be the perfect combination in a spreadsheet (I didn't calculate it), but with some tuning and testing, it might end up being very fast. We'll see this weekend.
I drove the car home last night and it definitely felt aggressive to say the least, but not unbearable. I still want a suspension that I can drink a Starbucks in. Call me a snob, but I gotta have my coffee.
I had to meet AJ from Performance Speed Tech (shop at MSR) this morning to deliver a part for a customer. We met in downtown Fort Worth which is 65 miles one way for me. I figured it might be a good test for the new package. I revalved the front slightly and did nothing to the rear. The rear has been working well on soft settings so no need to go up. The front we were running at full stiff so with the increase in rate I upped the rebound valving. North Dallas to Fort Worth is a great test for a suspension. Concrete side streets, new concrete highways, old concrete highways, new asphalt and old, VERY old asphalt highways make up the trip. Not to mention downtown Fort Worth is a disaster of construction. You get a mix of every bump you could ever imagine.The trip to Fort Worth was comfortable, still aggressive. Definitely not coffee cup worthy. The car was pitching more than I like, and it was pretty obvious the rear of the car was the likely problem since I had them full soft and 6 clicks on the front. After meeting AJ I turned the rears up 5 clicks and drove back to our shop down the same roads. It was a night and day difference! The car was super smooth, obviously stiffly sprung but you could definitely drink your favorite beverage now.
Why do I bring all this up? Aside from the fact that it proves that monotubes can do a great job of controlling high spring rates without beating you up, it comes back to all the chatter we hear about critical damping. Yes, the theory and practice of trying to find the "perfect" suspension via calculations works, it can never beat the actual practical testing on the street. With a simple turn of the knob, I was able to match the front and rear frequencies of the suspension without too much effort. I reached in the trunk, turned two knobs, and was done. I can probably tell you that 700/800 won't be the perfect combination in a spreadsheet (I didn't calculate it), but with some tuning and testing, it might end up being very fast. We'll see this weekend.
Last edited by hancheyb; Mar 13, 2009 at 08:00 AM.
Mar 13, 2009, 08:09 AM
#78
It is better. I'm running 784 (14kg) all around and the car is very nice on the track I have a set of 12kg springs (672) that I guess I might throw on the front if ya'll smoke me this weekend 
(Imitation being the most sincere form of flattery and all).
I have a set of 12kg springs (672) that I guess I might throw on the front if ya'll smoke me this weekend (Imitation being the most sincere form of flattery and all).
Mar 16, 2009, 02:51 PM
#84
A couple poor videos of this car at the AutoX this weekend. Amy drove the living snot out of it.
1st run by Terry (in the middle of the video) - http://www.youtube.com/watch?v=bdITfcw5M2U
2nd run by Terry - http://www.youtube.com/watch?v=aq8KiXAWgfE
Sorry for the poor angle, etc, but I was having to work, so I just stuck my camera on a wall and let it record.
Make sure you wait for YouTube to process the videos so you can watch them in "HD."
1st run by Terry (in the middle of the video) - http://www.youtube.com/watch?v=bdITfcw5M2U
2nd run by Terry - http://www.youtube.com/watch?v=aq8KiXAWgfE
Sorry for the poor angle, etc, but I was having to work, so I just stuck my camera on a wall and let it record.
Make sure you wait for YouTube to process the videos so you can watch them in "HD."
Mar 19, 2009, 07:57 AM
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Well, I was hoping to have all the race results in before I posted an update from the weekend. Last Saturday Terry and I took the Evo to MSR for the NASA event. The weather was pretty bad when we got there. It was in the low 40s, still raining and misty. The track was super slick. We were there late, but no point in going out since the weatherman said it would dry out slowly. Time Trial is a "best lap" effort so there's no point in beating the car up.
And it was sloooow to dry. The track wasn't fully dried till our 4:30 session later that day. Our first afternoon session was almost dry. The car turned a 1:27 in still slick conditions. That was good for 4th in the group behind two Vipers and a ZO6. The last session had some more "big guns" come out and the guys with R compounds started showing their grip. We managed a 1:25.1 in the Evo which was good enough to win TTA, and be within a few tenths of being a front runner in TTS. While a 1:25 isn't super fast when you consider the Evo is 3600 pounds and we still have the Dunlop 245mm street tires (Star Specs), a 1:25 doesn't sound so bad. A lighter, raced prepped E36 BMW usually runs 1:24s on Hoosiers for a comparison. So given the cold weather, the drying conditions and the prep of the car, we were happy with the results.
The car felt really awesome pretty much everywhere. It could use more power, but turn-in, mid corner, and corner exit were all great. For once, it had a touch of oversteer which was nice and much different than our first event at Eagle's Canyon on stock suspension. I was getting pulled on the straights by all the TTS and up cars, but usually closed the gap in the tighter turns (thank you autocross!). The Evo was definitely fast in the turns making 1.28g according to the DL-1. It made 1.15g in braking a time or two. And an interesting side note, when you start making 1.28g in an Evo you have to fill the tank every session. The Evo is thirsty on the track. Even with 5/8 of a tank, the car will suck air at some point. With stock suspension we could make 2 - 20 minute sessions, not anymore.
Sunday Terry and Amy took the Evo to Pennington Field for a SCCA autocross. Amy ran in "Women's" and Terry ran in the "X" class. Both classes are PAX based. Since he's probably running different cars this year, he wanted to be in a class that allowed that. Amy smoked even STU Open with a 37.2. That would have won STU by 0.4s! Terry was a few tenths behind with a 37.4. Amy wrapped up the 10th spot in PAX in a field of 148. That's an encouraging result, but still the car was 1.5s out of 1st place in PAX which means we'll need to do better to place well at Nationals. Considering the level of prep, this definitely was a promising finish in its 2nd autocross ever (with shocks). The transmission comes through again with some 2-1 downshifts and 2-3 upshifts you'd never dare do manually. Thumbs up to the SST!
Needless to say, the new spring rates really helped at the track and autocross course. Terry said the car turned in so fast you had to rethink your driving. This is definitely a change from the first autocross at TAMSCC where it was a little sluggish.
New things coming soon:
- Race seats - get some of the "lead" out. The car is making enough grip now that even the awesome stock seats aren't cutting it.
- Yokohama AD08s - this should be worth a few tenths at least over our beat up Star Specs, most likely much more.
- Lighter and wider wheels - we'll probably get a 18x9 or 9.5 for the car, possibly 18x10s for the track wheels.
- Lighter brakes - see if we can't get some weight off the front with some Racing Brake goodies. The stock brakes are still marginal at best on the track.
Mar 19, 2009, 08:10 AM
#88
AMS makes a surge tank that will keep you from having to run > 1/2 a tank. @ $600+ I'll just keep filling up every session, but ya'll can afford it
BlackTrack says he can go out with just enough for his session and it keeps the car from starving itself.
BlackTrack says he can go out with just enough for his session and it keeps the car from starving itself.
Mar 19, 2009, 08:14 AM
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I knew they had one. That would definitely be protested in STU and since it isn't something we can easily change like boost and fog lights, I didn't want to do it.