Quarter mile query

[colm_mcm]

The plan is to fit 15" steel wheels with 195 50 R15 tyres for the quarter mile.



Questions for those with the cognitive capacity/online calculators are:

This will surely help my time, it's hardly likely to be slower than standard wheels?

the speed limiter kicks in at 180kmph, I'd hope to be doing 95mph (should be thereabouts for an early 14's time?) at the finish line, will the limiter think I'm doing 112mph or over with this tyre size?

Is it worth fitting the delimiter (have one) just for the 1/4 mile, heard they can be a bit dodgy. can I disconnect the speed sensor to fool the limiter somehow?

Or should I just chill?

[Dragonheart]

Thought the limiter kicked in at 200kmph, ie 121mph?

[colm_mcm]

well, the clock only goes as far as 180

[Bernard]

I think DH is right, the limiter will bring you back to 180kph but doesn't kick in 'til you pass it.

For piece of mind take a look here (bottom of page), there doesn't seem to be a huge amount of inaccuracy with different wheel sizes...

[colm_mcm]

I may want to go lower profile than that then. I want better gearing, smaller outer radius is the way forward I think

Have access to an accelerometer 1/4 mile 0-60 thingy,

will give it a blast before the day to make sure there actually is a benefit.
(on my own private test track of course)

[Dragonheart]

My clock goes to 200 but it is aftermarket, but I always thought the standard clocks went to 220. Prob wrong, that was prob another aftermarket one so. But I'm pretty sure the limiter is def 121mph, even thinking back on Tokyo drift remember the cops wouldnt attempt to catch the RX-7 cause they could only do 180 and the rex was able to go higher, and I dont think they can delimit in japan can they? And yes, I know its only a film!

[TopCat]

Pretty sure the limit on all Jap cars is 112mph. Heard it again recently in relation to the Nissan GT-R. Has a GPS that recognises when its on a race track and takes off the limiter. Sweeeet....

[optical illusion]

AFAIK all Jap cars are limited to 180. My car came with a delimiter, and of the two guys that had it before me, one of them did well over 200 in it (you can check the overall max speed on it)

[Myfeckin FTO]

The plan is to fit 15" steel wheels with 195 50 R15 tyres for the quarter mile.
.........................
the speed limiter kicks in at 180kmph, I'd hope to be doing 95mph (should be thereabouts for an early 14's time?) at the finish line, will the limiter think I'm doing 112mph or over with this tyre size?.......

....Is it worth fitting the delimiter (have one) just for the 1/4 mile, .................

Have you test fitted the 15inch steelies? Do they go over brakes etc ok? Correct offset and bore etc?

You'll be doing very well to have a 95mph terminal speed - And if you can get this speed you'll likely be doing late 14's (depending on your launch time). The difference between a 215/40 R 17 (1896.89mm) and a 195/50 R15 (1809.56mm) is still actually just 4.6% so your speedo will read 99.4mph when you will be doing 95mph - so the delimiter is unneccessary.

See - http://www.carbibles.com/tyre_bible_pg2.html
for more info in relation to tyre profile calculator.


On another note - tyre type will be important - what tyres are you running on your 17's and on the 15's?

Also can you check the weights of the 15inch steelies against the weights of your 17's (with tyres)? I'd be very interested to see what the differences are.

[Sebastian]

acording to my gps , car cuts at 186 km/h
thats on my private road of course.

[Bernard]

acording to my gps , car cuts at 186 km/h
thats on my private road of course.

Mine's derestricted

[Muad_dib77]

I didn't get near the limiter on my runs last year...

[colm_mcm]

The tyres on the 17"s are 215/40 R17 Yokohama Grand Prix's,
I haven't got the steel wheels yet, but I can use some 16" original alloys if they're going to give simlar results, theyre likely to be wider than any 15" wheels too.

Maybe a low profile 16 is the way to go, not hugely common though.
With 15 it's very easy to achieve the smaller outside diameter.

First things first, get the steel wheels then see!

[Dean]

acording to my gps , car cuts at 186 km/h
thats on my private road of course.

Mine's derestricted

Did you go back in time?

[Myfeckin FTO]

.................
Maybe a low profile 16 is the way to go, not hugely common though.
With 15 it's very easy to achieve the smaller outside diameter.

First things first, get the steel wheels then see!

In an ideal world - I'd give a couple of scrap yards a call (or MOC forum) and see if I could pull a couple of aftermarket lightweight 15inch alloys from a Colt/Mirage etc and stick a couple of Toyo R888's on - Camskill do a really good deal on these - http://www.camskill.co.uk/products.php? ... 2b99s661p0 - could then use for trackdays etc as well.

From a practical perspective if you are going to buy rims/tyres then its possibly just better to buy a grippy set of tyres for your front 17's that you can continue to use esp if your 17's aren't significantly heavier than standard 16's.

At the last couple of 1/4 miles where I ran the FTO I ran my everyday 17 inch rims (215/45) but spent the money on good rubber (Potenza RE0500 which I could use on a daily basis). Grip is gonna be one of the bigger factors in launching an FTO.

Don't bring a set of brand new tyres to a 1/4 mile - they'll need at least 500miles on them first to wear in.

Colm - Camskill have offers on F1 Eagles and Toyo T1R's in your 215/40 17 size
http://www.camskill.co.uk/products.php?plid=m4b0s103p0

[kevinod]

IIRC, with the limiter it's when you hit 120mph it brings your speed back to 112mph.

[colm_mcm]

Food for thought.

The Yokohamas have loads of tread left on them, and are very grippy, don't want to shred them to bits on the track.

MfFto, aren't Colts 4 stud?

[Myfeckin FTO]

.........The Yokohamas have loads of tread left on them, and are very grippy, don't want to shred them to bits on the track.

MfFto, aren't Colts 4 stud?

You won't shred tyres to bits on a 1/4 mile as you'll never get that much heat into them and the FTO won't eat tyres like a powerful RWD or 4WD monster.

My bad - Colts are 4 stud - I was thinking about the platform and presumed Mirage and Colt had similar set-up.

Still a search on ebay/MOC etc for a set of 15 inch rims - 5 x 114.3 with correct bore and offset might turn up a set of cheapish rims that two members on here could share cost and take 2 rims each.