+ Register
|
Main Menu
Login
Fast Search Slow Search
Google Ad |
Browsing this Thread:
1 Anonymous Users
#56
Re: How do you guys get traction with high hp? And awd anyone?
L18_B110
Posted on: 2011/11/11 23:48
Quote:
real time data would be infra-red temp sensors. G force is simple accellerometers. There's heaps of affordable GPS timing systems with accellerometers available these days - every second guy at sprints/track days has them. Quote:
saw it a few years ago at the Aus Hillclimb CHampionships up here. He said it was using a Hilux transfer case, so its a locked 50:50 front:rear drive. Surprised me because transmission bind/wind-up should be an issue...  
#55
Re: How do you guys get traction with high hp? And awd anyone?
L18_B110
Posted on: 2011/11/11 23:42
lets get through your temp/overheating variables as well - a 155 won't have the same grip as a 195 when its dead cold launching from a standing start, or in the first couple of laps before its overheated, or in a short squirt through a couple of corners during general street driving (where tyres don't get excessively hot).
As I said, my example of the wider tyre was on the rear, so there is no scrub radius consideration! All I changed was the tyre width, not the wheel, so no change in track or offset which is why I didn't mention them. I have data that shows I was generating a fairly consistent 0.1-0.15 more G with the wider rear tyres on because instead of braking traction with the rear end, they just keep on gripping. You can throw in as many inapplicable variables as you want and theories as to why wider tyres don't offer more grip, but you'll have a dickens of a time convincing my accellerometer and timing system that wider tyres don't grip better.
#54
Re: How do you guys get traction with high hp? And awd anyone?
a12grunt
Posted on: 2011/11/11 15:06
Quote:
thanks for the pics, what a sleeper!!! If I ever get a Z it will be the ugly 2+2 with 103 inch wheelbase and will mod the roof to make it like the 2 seater instead. Also TB48 turbo six for that v8 and 2jz beating all nissan combo :) D, there is a reason most if not all the supercar beating tb48 turbo patrols running huge hp are in dubai...... money is not a limit And everything is compared to a 2jz(3 liter motor made in 1992),including tb48t, for a reason.... In regards to the tire temps, what type of equipment do they use to record such data as car is being driven?and where would the sensors be installed to measure the heat and wear in the tires and g-force on car? and there is a v8 4wd 240z in Victoria,Oz and it apparently handles very well.Many victorians might have seen it in easternats sandown before they closed/stopped the event.This 240z was very fast!!!Also runs wide rims/tires. Heres the link to one of its hillclimb events, http://www.youtube.com/watch?v=AQjXsvEhLyQ anyone knows which 4wd system he was running as it could help this thread?
#53
Re: How do you guys get traction with high hp? And awd anyone?
jmac
Posted on: 2011/11/11 10:40
I'm just going to leave it. you've asked the same question, about 'why not a 155' (albeit slightly differently worded) and I've answered it multiple times- that eventually you get to the point it just over taxes the small amount of tyre, it overheats or just plain tears it up, and it lets go. Oddly enough it _is_ actually proof that the tread is gripping as well. It's just that it ends up tearing itself (at the microscopic level) away from the tyre. I could just as easily ask 'well why not run tyres 2 metres wide?'
At 2 metres wide put more camber on that, and you'll get to the point that the outside half of the tyre never touches the ground during cornering. At that same camber level a thinner tyre can and will make full contact. I realise it's an 'out there' example, but it illustrates the point. Of course it isn't that simple, and that's what I'm getting at. you'd have to factor in where the weight is being transferred, and look at optimising it to hit the middle (more or less) of the tyre contact patch. You could also (demonstrably) get to a point with tyres where they are just so large (admittedly beyond the scope of any practical fitment) that it's impossible to get enough heat into them to make them work, in a competition sense. Take any sport bike, and with a competent rider, they will pull more g's for longer periods, under hard braking, than they can accelerate. The front does probably more than 90% of the braking? But oddly enough, using a smaller tyre than the rear. Now of course I'm deliberately doing an apples and oranges here. The rear tyre is bigger, so that (at similar overall treadwear rates for a given stressor on the same compound front and rear) the rear lasts the distance, since it is (overall) being used to transmit force for most of the time, the front doesn't come into play (relatively) much at all during the point of corner exit where the bike is mostly upright, and so on. You also want to factor in scrub radius changes, changes in offset and track (which I've mentioned). Like it or not, within sensible ranges, tread compound is important. As is suspension geometry configured to maximise download/weight transfer onto the tyre. They were the two points I made and I stand by them. Beyond that I'll agree to disagree. With regard to tyre temps, I used the term pyrometer, but I meant it as a more general term, I was just curious about tyre temps, of the previous set and subsequent set you used as the example. I wasn't nitpicking about _how_ they might have been measured. To which end, if you could expand upon whatever data you got on tread temps, I'll certainly read (but as mentioned I won't respond, it's clearly of no productive value).
#52
Re: How do you guys get traction with high hp? And awd anyone?
5zturbo
Posted on: 2011/11/11 9:12
Quote:
2 grand is a bit steep for a rear end set up like the r31 dont you think? Ive search all other the site and net, and found no cheaper alternative. Found a few guys converting to IRS and thats most likely my best and cheapest option. unless anyone else has a good option that can handle 350-400whp and launch on slicks (just incase I try them someday lol) ofcourse must be lsd
#51
Re: How do you guys get traction with high hp? And awd anyone?
1200rallycar
Posted on: 2011/11/11 6:29
sleeper? bet he's never heard it called that before!
#50
Re: How do you guys get traction with high hp? And awd anyone?
Posted on: 2011/11/11 5:45
I'd say you may loose some back seat room with the awd set up too and mounting points etc.
These guys race ca18 in rwd- see how they set it up . Why reinvent the wheel. They seem to be able to hook up with Tyres. Unless you want to mini tub it internally 
#49
Re: How do you guys get traction with high hp? And awd anyone?
5zturbo
Posted on: 2011/11/11 5:04
Quote:
well in that case cant really explain it either lol but are we talking about the same thing? back road racing for me usually means a set up race. example a challenge or what not. Usually just another way to show off your machine even though you know its fast. and ya I actually plan to track my bike this coming season. its on my to do list, and I wish I can track my car but the closest drag track is 2 hours away and only open to public on test n tune Wednesday. which means getting maybe 2-3 runs after spending 5 hours overall. alot of waiting in traffic to get there and waiting cuz every import likes to go lol ya looks like thats the way im leaning, did some major read and search of possible mid engine rwd set up but looks like I cant fit the engine back there without loosing the back seat... so back to square one. :(
#48
Re: How do you guys get traction with high hp? And awd anyone?
Rallytwit
Posted on: 2011/11/11 3:38
and I think you dont get it cuz its not for you. think of it this way A LOT of people dont get wtf we mod cars either in their eyes "whats the point?". different things work for different people.
btw im no way encouraging street racing, but i do my fare share of back road racing. and I do my fare share of mountain runs on motorcycle. Im sure people also dont get that to lol......................As someone who used to road race motorcycles I completely get riding quickly but what I don't get is trying to go reeeeally fast on the street, there is so much less traction available on public roads that the corner speeds are slower than yer basic warm up lap.................this is a particularly acute problem for me as my road racing background is in 2-stroke GP bikes, mostly 125cc but the occasional ride on TZ250's...........................if you haven't been on track with your bike, you must try it at least once, it's just an absolute scream.......you can slide the bike around like a hoon and not have to worry about what junk is on the tarmac...................with all that said I have threatened to put Super Moto Wheels on my KTM 300 (it's plated / street legal)............I'm also considering a new Beta 520 dual sport (you can slide a bike around on dual sport tires in a fairly alarming manner if you choose) OK back on topic: I can't remember exactly on shock settings for drags but I would imagine if you set the compression on the rear shocks a little softer and the rebound a little harder then the optimal road race set up that would help the rear bite. Sway bars selection shouldn't affect the straight line acceleration (anyone feel free to correct me if I'm wrong). As for ride height you could run the rear a touch lower / biased toward the rear, obviously it would have a little more understeer than the optimal road race set up. If you have a test n tune night at your local drags you could use that to dial in as much grip as possible............then maybe take it to a local autocross to make sure it still handles acceptable although once you round the first freeway on ramp you'll likely know . Grippy tires and a limited slip diff would also be a must as mentioned. Tom
#47
Re: How do you guys get traction with high hp? And awd anyone?
L18_B110
Posted on: 2011/11/10 23:34
Quote:
you shouldn't have mentioned it, because its completely wrong. the wider tyre will gereate more lateral grip and work better with more camber to optimise its contact patch during cornering. Same goes for if you upgrade from semis to slicks in the same width. More rubber on the road means more surface area interacting with the road and more grip. Again they like more camber as a result. Quote:
you're not even reading, just arguing your points over and over - as I said last time, "it's obvious that different types, brands and models of tyres offer different amounts of grip. No one's arguing that. But as per my example of the exact same tyre, you get the more grip from the wider widths. Thats removing all those variables" Quote:
as someone who actually uses slicks and semi slicks over the past 10 years, I like to find out what I'm paying $1600-2000 a set for. Kumho slicks and semis - come in 3 compounds. You choose which compound you want in whatever size you buy. Dunlop DZ03 made in 3 compounds. You choose your compound. Yokohama A048 - made in 3 compounds depending on size. Contrary to your assumption, Australian availability of compounds is such that bigger sizes come in harder compounds to suit larger heavier cars. Yokohama A050 - made in 2 compounds in each size. you choose. Bridgestone RE55S - made in 3 compounds. you choose. Toyo R888 - 2 compounds I know of - GG and GGG. Aus distributor network only has one compound available - GG. Can special order the softer GGG though. Toyo RA1 came in 2 compunds. Earlier RA1 (which were on the 230rwkw 1200 I had) had a UTQG of 40 and were the gun tyre for hillclimbing and wet conditions when they first appeared on the scene. Later tyres all had a UTQG of 100, which is the same as the R888 GG. Federal FZ201 make 2 compounds. You choose. there's more brands available, but you get the idea. Summary is no tyre manufacturer makes the wider sizes of their performance tyres in softer compounds as you claim. Even in street tyres, the model of tyre has a compound used accross all sizes in its range. EG all Kumho KU36 are 180 UTQG. All Federal 595RSR are 140 UTQG, etc etc. Tyre manufacturers don't waste money making several slightly different compounds getting slightly softer as the tyres get wider as you seem to assume. The production costs would be outrageous! Quote:
Like 99.99% of club level racers, I don't have a pyro. I use an infra-red temp gun to get surface temps to see if the camber and pressures are in the ballpark. Admittedly more useful for pressures which don't drop off very quickly, but still better than nothing for checking out camber. My current FZ201 medium compound hit between 55 and 65 degrees across the tyre surface - LF & LR around 65deg, RF about 60 and RR about 55deg at Lakeside IIRC. Quote:
what you came across as saying is that width has absolutely no influence on grip: Quote:
If a 195 has exactly the same grip as a 235, why wouldn't a 155 have the same grip as a 195? Given that tyre companies aren't making different compounds for each size of tyre, we should choose the appropriate brand/model of tyre for our intended purpose and then buy the narrowest size they have in that type of tyre because the wider ones have no more grip... its just not the case as my example of going from 235 to 255 in the FZ201 Medium compound shows.
You can view topic.
You cannot start a new topic.
You cannot reply to posts.
You cannot edit your posts.
You cannot delete your posts.
You cannot add new polls.
You cannot vote in polls.
You cannot attach files to posts.
You cannot post without approval.
|
