AZSP33D

My experience with the RT660 275/40/17 on the 17x11 has been positive. After a dozen heat cycles (plenty of life left) I ran them at a test and tune and had a new set of 18’s with 285 and 315 Nankang CRS tires to swap in for the second part of the day. The overall grip of the CRS was a little better, but I think the precision confidence and turn in reaction of the RT660 was better. The sidewall is stiffer on the RT660, even with the taller sidewalls.

Regret for that new 18 combo: maybe I should have used the proper 25.6” tall 275 CRS in the front instead of the 285 CRS which was 1/2” shorter, so the front end geometry was better. Lots of tricky roulette with trying things, but the conclusion is that the 275 RT660 held its own. The 18’s are fine, my times dropped by about a half a second with brand new tires, but maybe not worth the $3K+ investment.

VikingTrad3r

Thank You very much for the comment!!

I will try putting the 275’s on the rear. i dind the tire compound to be incredibly sticky. The other thing is they like seriously high tire pressure. Like 45 hot.

I will mount these rear, and, take the time to pull my fx3 actuators off, and manually turn them full stiff. that should get me a new pb. 👍

MatthewMiller

Viking, I have a few thoughts. The car will start understeering again if you swap from the Toyos to the Falken 660s in back, because you'd be increasing traction only at the rear. If you can source a larger rear sway bar, you should consider at least bring it to the track along with the minimal tools required to change the rear bar (you probably don't even need a jack to do this). You can try the car with both rear bars. The larger rear bar will effectively shift some of that new rear grip to the front end in turns. Another option would be to buy two 17x11 wheels with 50mm offset for the front and shod them with 275 Falkens also. OE Wheels sells those cheap. Also, if you turn all your shocks full stiff, that might help the understeer at turn-ing and corner exit, depending on what the shocks have been doing on their own. No way to know that until you try it.

I'm inferring you're running 275/40/17 Falkens on 17x9.5 front wheels now. That's probably a slightly pinched fitment. The RT660 does like higher pressures than some other competition street radials, but the pinched fitment also exacerbates that. That same tire on a 17x11 in back won't want as much pressure. I'd target 35-36psi hot and see how that goes. As a sort of reference, I was running 305/30/19 on 19x10 front wheels on my Camaro for autocross use (another pinched fitment), and I kept them at 36psi hot (bleeding off pressure between runs).

ChumpVette

Getting around to finishing the brake cooling ducts while waiting on some electrical pieces to show up.

VikingTrad3r

Chump the cooling duct intakes look sweet.

3”?


————-.

If any of you have advice i am very receptive to learning!!!

Last lapping day of the season up here. Was a fantastic day. I cannot get over how incredible a factory z51 car is. Just mind blowing. I’ll past below the link to my new pb lap. Prior to this it was a 151.4. Now 151.04. And the best part is this happened with many other cars on track. There were several times where the detla shows i was well into the low 150’s.

All this with an overheating engine (i was having to short shift…u can hear it in the video…my coolant temps were 117C (242f). Blowby out the dipstick (im thinking unfortunately its the rings that are worn. No smoke out the tailpipe. Just the dipstick tube and onto the exhaust manifold shroud.

Tires have 11!! ELEVEN!!! hard track days on them. I have been running them with high psi. I left with 35psi cold. Ambient was only 17c (62.5f) but they were still well into the 40 psi hot. Dang the rubber got HOT. Finally on the 11th track day and last day of the season i chunked the front driver side tires on the outside edge. I have started to really employ trail braking, learning the modulation, and i think that just overheated that tires outside edge. Clockwise format. Right hand turns. Need More camber, but, i want a stock setup. Sounds crazy, will opt for bending the K member first.

You will see me blowing some apexes by a couple feet. This is happening as i get faster and faster (carrying a couple extra kph into a turn) its me behind the 8ball and i am missing turn in points, adjusting, adjusting, adjusting. There were two instances where my factory j55 brakes boiled coming into turn 2 (after the high speed right hander). You can either hit the pits, or, what i did was try to brake less. It did work. Less braking! I used to think guys were joking when they would say that. Nope, its how you go faster. Just takes seat time.

Lots of traffic on the course. We are all members, and all friends. Many of these guys i met a few years ago in a local endurance racing league and then may of us became members here. Great times.

I have committed to getting my caged C4 race car done by mid feb. So, all my other projects are being shoved to the back burner. Great season!!

If there are any aspiring youngsters out there who want to see how very little capital outlay and sweat equity can get you into an extremely capable track car out of the box, here was how i acquired, cleaned, and sorted this car for very little money.

(yes, still needs paint)

yakmastermax

Found a decent deal locally on some C5 magnesium wheels.

Thoughts on these for the track for my 85 Z51?

I would need to run some hefty spacers...

Is the weight reduction worth the hassle?

FAUEE

They're barely lighter than the aluminum ones, are staggered, and not worth it IMO. Run a square set of z06 wheels if anything (I'd go with z06 rears all around to open up brake and tire options).

I less you've gone all out chasing every extra pound that can be removed, IMO not worth it.

VikingTrad3r

agree. Staggered sux. a cheaper (albeit with adapters) option is c5 wagon wheel Rears all 4 corners. Also light. Very strong.

MatthewMiller

Generally I agree with the others: there's no performance merit to staggered wheels - these are staggered in both width and diameter - and the weight savings is completely insignificant.

VikingTrad3r

I cant find em.

would much rather weld in a simple sbc kit. They are available for LS. Other than buying a very expensive pan….has anyone found one for sbc’s?

I simply dont need an accusump. Just a bit more oili g control is all i need. Cheers.

MatthewMiller

I've never seen such a thing. All the oil pan companies that make baffled pans are putting the baffles in the section they add on to increase capacity and form the kickouts. FWIW, the Kevko 1091-RR is a better aftermarket pan than the Canton equivalent and runs $360 directly from Kevko.

Wogden

So ae the track season approaches I'm getting ready to pull the trigger on some new tires and getting rid of the Nitto 555. I'm currently running Grand Sport Wheels so 17x9.5 in the front 17x11 in the back but I have the original set of Z07 sawblades wheels which are 17x9.5 all around. Reading through some of the above comments it sounds like ditching the staggered setup might be a better track option and just going with 275 40 17s all around. It should open up more options for tires and make them easier to rotate if I want. Also ill now have two sets of wheel and tires. Track and street. Do you agree with my thinking?
I'll probably do at least 6 track days this year. Id like to get a season out of the tires if possible. Suggestions?
thanks.

bls72bmw

Wellll honestly- sell off the 17s and grab a set of reasonable priced 18" rims...and a set fo Goodyear Supercar 3s... A higher initial investment BUT a much better set up IMHO......

I bought some cheap 18" rims from OERims. They're cast. And I carry an extra set of rim/tires in the event I have an off and one of them cracks. But so far they have held up well.

VikingTrad3r

I 100% agree with ur thinking. Ive been buying cheap rims when they come up. 2 sets of amolds and 1 sawblade. i buy falken rt660’s. always have a set ready new. I keep my old ones so if im going to the track to show friends i put on a set with minimal tread left as im not pushing 100%.

square setup will spank the staggered. especially if rt660’s or better.

what year and suspension setup are you running?

Wogden

94 Z07 6sp coupe.

VikingTrad3r

If you are a stock car and enjoy it stock (i do) then yes i buy the rt660’s in a square setup.

If it were a race car or otherwise customized (i have one of those too, hasnt seen the pavement yet, not sure what tire/wheel combo i will run but it wont be stock) then as suggested u could swap out rims.

The rt660 tires are very confidence inspiring!! The square setup is divine.

Would love to see vids of your car on track 👍

yakmastermax

Good to know, as the 17x11" wheel is pretty common for a lot of us. Looking at the picture it also doesn't look that stretched at all really.

MatthewMiller

In general, I agree with having separate sets of track and street tires. I don't generally agree that narrower wheels are faster: wider is better, and I can always adjust the handling balance with different rear sway bar sizes if a wider rear tire induces understeer. However, the problem with the 17x11 is tire availability: there just aren't any good track tires in 315/35/17. You certainly can stretch a 275/40/17 onto it, but then you'd probably want a 245/45/17 for the front 17x9.5s just so you have matching stretch and steering response front and rear. I'm not sure that combo is faster than the 275/40/17 on 17x9.5 both front and rear, and you then have the ability to rotate tires between track days for better wear. So in this particular case, I'd do that instead, and save the staggered set for street tires (315/35/17 rear and 275/40/17 front, and the Michelin Pilot Sport All Season 4 is a great-performing all-season in these sizes). If you had a set of four 17x11s, I'd say use those on track with 275s, but you only have two.

For track tires on the 17x9.5s, you can certainly do the Falken RT660. It's a great-handling tire with lots of grip. It will eventually lose some cold grip with heat cycles. However, this may be less important for track duty because you'll get them hot after a single lap anyway. These are not the longest lasting tires for track duty, but it depends a lot on how hard you actually push (i.e. how much slip you generate in each direction). We don't have a good way to gauge that here. A set of these will be $1024. The older-but-still-nice Falken RT615K+ is still available for $860/set. It's a little slower than the 660, but still a fairly fast 200tw tire, and it should last somewhat longer as well. If lap time isn't super important to you (i.e. you're not in a competition), then these could possible cost half as much per lap as the 660s and still give you plenty of grip. Splitting the two Falkens in lap times is the Continental ExtremeContact Force. You'd have to run 255/40/17s in this tire, and those would be about 1/2" shorter in diameter. They would fit fine and perform well. These tires handle great and wear like iron. At $1040, they are similar in price to the Falken 660, a bit off their pace, but will outlast them without question. The Goodyear Supercar 3 is a great track tire in much the save vein as the Conti, but it's not available in a good size for you. As much bls72bms's advice to buy 18s and get the Goodyears, that's not a cost-effective solution as long as these three other options exist for your existing wheels. There's a great , and it's worth 11 minutes of your time to watch it and/or read the written report.

Wogden

@MatthewMiller
thanks for your input. I'm not competing, just doing HPDE and the occasional TT. Im still a novice and learning and really just out to have fun. That's why I bought the car innthe first place, for FUN!
Still on the fence between the two Falkens. Your comment about cost per lap makes alot of sense.
Shopping on Tire Rack they offer "Heat Cycling" to prep the tires. Do you think this is worth $15/ tire or is it snake oil?

MatthewMiller

Heat cycling is not snake oil, but you can do it yourself for the cost of 1/2-gallon of gas if you prefer. Once the tires are mounted and the wheels put on your car, you can go drive it in "spirited" fashion, especially in braking, for a few minutes to get them warmed up. Then drive home and let them sit for 24 hours. Now they're heat cycled.