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Charlotte had a good ES class with Peterson, Wayne, Minehart, Ellison, and Lindley. Initial conclusions: the 1989 944 just does not have enough wheel and tire for the weight.
The videos show that Day 1 the car was still a little bouncy and I was driving it like it was as wide as the Corvette. I got 2 reruns which helped a lot but was still 9th or 10th of 15.
For Day 2 I took 50% of the adjustment out of the Tarret front bar which was still on full stiff, left over from before the bump stops and found more optimum tire pressures for the surface. The car was easier to drive, if not quite as darty and had better grip. (I will try adding back 25%) No bouncing at all, the transition onto the bump stops is fine, the car is well-balanced and I finally drove close to the cones. I actually ran over the base of a cone once though I never knocked one out of the box.
I drove the final run yesterday about as good as I can drive. No mistakes, at the limit and my line was exactly as-planned. (As-planned may be wrong, however!) Still way off the pace of the top drivers/cars on a course that was good for the 944. I will drop 20 to 25lbs from the exhaust and get the anti-lock working but those are the only major things left, less head reconditioning.
Last year at Nats Day 1 on the corn side (dry) I was 1s off the pace of the top time in BS on a 60s course. If I give myself that 1s to the leader yesterday the car is about 1.5s off the pace.
As it is, 2.5s back from the lead on a 60s course would have put me out of the trophies in ES at Nats on the corn side last year. Not too far out, but out. That's the optimistic way of looking at it.
More realistically I was just a little faster than the Robinson brothers which would have put me right at the 50th percentile at Nats last year in ES.
Death To Miatas (and MR2s)
PS: Question- anybody think I could get a 245-40-17 RE71R on a 7" wide wheel and a 255-40 on an 8"? (Actually, the same sizes are available in Rival 1.5S)
Ed, I wouldn't read too much into results at zMax; that sealed asphalt gives a MASSIVE advantage to cars with low dynamic ground pressure. You're, what, about 3100lbs? And MR2 Spyder is about 2200? Same course anywhere else and the results could have been completely different. Same with balance; zMax appears to cause a large loss of traction to whichever end of your car is heavier: Front-engine cars tend to push terribly, and mid/rear-engine get super loose. The surface seems to favor Hoosiers and RivalS over RE-71R and RE-615k+, too.
PS: Question- anybody think I could get a 245-40-17 RE71R on a 7" wide wheel and a 255-40 on an 8"? (Actually, the same sizes are available in Rival 1.5S)
I ran 255/35-18 RE-71R on an 18x8 wheel for several years. Extremely difficult to mount, but worked. If I recall, some of the S2000 guys are running 245/40-17 RE-71R on 17x7 wheels.
Ed, I wouldn't read too much into results at zMax; that sealed asphalt gives a MASSIVE advantage to cars with low dynamic ground pressure. You're, what, about 3100lbs? And MR2 Spyder is about 2200? Same course anywhere else and the results could have been completely different. Same with balance; zMax appears to cause a large loss of traction to whichever end of your car is heavier: Front-engine cars tend to push terribly, and mid/rear-engine get super loose. The surface seems to favor Hoosiers and RivalS over RE-71R and RE-615k+, too.
I ran 255/35-18 RE-71R on an 18x8 wheel for several years. Extremely difficult to mount, but worked. If I recall, some of the S2000 guys are running 245/40-17 RE-71R on 17x7 wheels.
Thanks.
BTW, I'm thinking the car is ~2850lbs on low gas and no driver, but haven't weighed it yet.
I don't know exactly about the bump stops, but I'd also bet they leave linear range with very little travel, similar to reaching coil bind on a traditional spring. I think there's a real chance your wheel rate is spiking to near infinite in some situations, maybe a lot of situations.
I guess if you're real bored you could switch to bump springs, which would probably stay pretty linear in rate up to ~80% of travel, but even a 2" bump spring only has maybe 1" of actual travel until coil bind, rate dependent.
I don't know exactly about the bump stops, but I'd also bet they leave linear range with very little travel, similar to reaching coil bind on a traditional spring. I think there's a real chance your wheel rate is spiking to near infinite in some situations, maybe a lot of situations.
I guess if you're real bored you could switch to bump springs, which would probably stay pretty linear in rate up to ~80% of travel, but even a 2" bump spring only has maybe 1" of actual travel until coil bind, rate dependent.
I'm rating the bump stops after 1/2" of travel, so if a pair develop 200lbs of force at 1/2" total compression I call it 400lb/in. For 2 and 3 donut stacks they are all pretty linear up to about 3/4" of compression, which I figure is enough, but they're not bad even after that.
For instance, the green line on the attached chart is the curve for the 3 blacks (50A durometer) I'll be installing on the front struts.
As for bump springs I'm not clear on how to implement them legally. Glue (tack weld?) a spring together with two retainers and let them slide on the shaft? I don't know how they're usually done.
I took the car to a friend's house today for engine health checks. Compression was good at 200, 200, 205 & 205.
Leak down was ok also at 6%,4%, 6% & 9% (#2).
As I'm putting the spark plugs back in my friend pulls out a bore-scope. We look at cylinder one. (In this engine, like the 3.0 liter S2, cylinders 1 and 2 are siamesed together as are 3 and 4.) The piston looks good. Carbon in the middle but not around the edges. (I've done 2 Seafoam treatments.) The wall looks good with maybe a barely visible scatch or two. Then I see something strange: it looks like a drop of coolant running down the wall. Hmmm. My friend says he thinks it's oil. But, that's doesn't really make much sense to me and looks too thin to be oil.
I start the car and back out of his garage. He motions to me. There's a large puddle of coolant on the floor. More coolant has been trapped on top of the bottom panel and comes out when I back up more. It looks to have originated from the overflow tank vent line. (There's not a drop on my garage floor.) At our first event here in Huntsville some coolant came out in grid. At the time I figured it was just hot overflow from too much in the overflow tank, though I had filled it just to the mark.
Gotta be coolant pushed out by the 80psi leak-down pressure, right? Through the (failed) head-gasket?
Update on engine: bore scope shows all 4 cylinders have coolant intrusion to some extent. The good news is no white smoke, no overheating, no visible water in oil, engine runs fine, was unable to force coolant out with cylinder pressure or even hear any gurgling or see any bubbles. Still planning on a new head gasket sooner rather than later.
Update on setup: I changed the front bumpstops to get as close as possible to 2.2Hz with 1 yellow and 2 blacks on each strut. Ran local event today: increase in grip was evident. Front end moves and rolls some. I added a little more front compression and rebound at the lunch break. I won ES by a large margin and paxed 4th overall of 107. I expect to add a little more front bar for grippier surfaces.
The Grenada Pro-Solo was disappointing, but instructive. Saturday was a flood and I didn't have Contis. I must have been the slowest car in the entire event. Sunday I had 4 dry runs before rain impaired the last 2 of 6. I matched my local guys, the Goofy Gomers (both have PHDs, btw) on the left side, but screwed up the right 3 times. Even on the left I was depressingly far away from the top, about 1.5s from first and 1s out of the trophies on a 32s course.
I've bit the bullet. I have a set of Cup 1's in 17 by 7 and 8 coming. Will go to RE71R 245 and 255, assuming my tire guy can get them on. 7.3% wider tire patch, in theory. And it will get me to 56mph in 2nd instead of 51. Most of the fast ES cars are running 225s on their 6" wheels. With my 225 on 7 and 245 on 8 I've had only slightly more rubber for a lot more weight.
I don't want to make it sound like it's all the car, it's not. I think the car has about as much grip as the Gomers now, but probably less than the 225 folks. Last run on the left side I finally woke up a bit and drove it better, unfortunately it was raining again by then. This momentum maintenance thing is tough. Very hard to know the correct trade-off between carrying speed and adding distance. Still learning that. Basically, I use the brakes too much leading to periods where the car is not at the limit and has lost too much speed. I could see that others were adding only a slight amount of distance in order to produce a much higher average speed.
I ran into Sam Strano at Charlotte. He knows me from my Corvette-driving days. He asked, "What are you driving now, something weird I saw?" I told him I went to a 944 in ES to learn momentum maintenance. He said, "Well, you picked the right car for that!"
245/40 on 7 and 255/40 on 8, RE71R Bridgestones. Badly scuffed-up 17" Cup 1's I got cheap that I'll plasti-dip glossy white.
Tire guy said only slightly more difficult to mount than normal. Didn't charge me any extra.
It will be a while before I get to test them out. Missing the next local due to a trip next week.
These 17s seem huge. 9bs heavier per corner, wheel + tire. Gearing change is very evident, as is the faster response from the Stones. The "true 8" wheel" variation in offset gives it a little more rear track as well as compared to the widened 7" phone-dials where all the new width went to the inside. Edge of rear tire is now +10mm closer to the fender on each side. (Still legal with the 7mm spacer.)
Removed the cylinder head and took it to Memphis Motorwerks for reconditioning. The pic is of piston #1 mostly cleaned of carbon. I should have the head back next week. Little to no corrosion, not warped, so just a few thousandths skim of the surface is all that's needed. All valves cleaned up good. There was some pitting on the back sides of the exhaust valves. New guides, new springs.
The head gasket was in really bad shape, allowing coolant intrusion into the cylinders, as seen a few weeks ago by bore-scope. Some think you should wait until you see white smoke, poor leak-down or compression or other obvious signs. I don't think so. If you are losing any water in a 944 find out why. 944 fiber head gaskets should not go much beyond 100K miles in my book.
So I'll have a freshened engine for the Bristol events.
03-24-2019, 11:38 AM
