hey I just read another thread where ppl mentioned their speedo being off and losing 1-15 hp by putting 18 inch rims on a fc. I am planning on doing my 5 lug conversion and putting fd rims on. Will my speedo be off and will i lose any hp?

 

you wont loose hp... And the speedo shouldnt be off if you put the correct tire size on the FD wheels making them the same hight as stock wheels with tires.

 

Your speedo will be off unless you use the correct size tire.

You can use this calculator to test stock size versus various sizes you'll be running with your FD rims to see if it's any different.

http://www.miata.net/garage/tirecalc.html

 

Correct, you will not lose any horsepower. How much your speedo is off is dependent on the tire size you choose. However, due to the new tire and wheels possible larger mass(as well as being rotational mass), there could very well be a decrease in your vehicles acceleration despite there being no change in horsepower.

 

Very few racers seriously use 18s.. thats just for show.

There will be a big change in accelleration and handling: both will suck.

 

If you are going to put FD rims on, don't forget to use spacers and extended lug studs(if not using bolt on spacers).

 

HP losses are dependent on the weight of the wheel. For the clueless ones that say you don't loose any HP- Honda (as well as many others) have proved and published that figure a 5 DWHP (Drive Wheel Horse Power) loss for every 5lbs of wheel mounted on every corner.

So if you used 25lb 18 inch wheels, on a FC that had the stock 17 lb balony slicers, you would loose about 8-10 RWHP.

Or is you replaced those above mentioned Balony slicer wheels with the 'verts BBS wheels, you would gain about 5-6 RWHP.

This has been proven over and over... so again ignore the clueless ones who say there is no loss. Technically there is no loss of Flywheel HP, but there is most certinly a loss of drive wheel HP.


as far as wheel size, it will be dependent on what you are doing with them. For a street performance car 17 inch wheels are the absolute largest you would want to go. The suspension is not calibrated to be fast enough to control and respond fast enough for anything with less tire. Most AutoX drivers use either a 15 in (or a few use the 16 inch). Most long term FC owners use a 16 inch for a street performance driven vehicle as it is a good comprimise between weight, and tire size as well as the suspension is set up for a wheel of that size. Again lightness is the most important thing for maximum performance, both on the track and on the everyday roads. Lighter the wheel; faster the car is; faster the suspension is.

 

Rotational mass is very important. Same goes for the brakes and drivetrain items.

 

run stockers! no one wants to steal them

 

Ok so I have phone dials right now and when i put my fd's on (longer studs and 25mm spacer) should I experience a great lose. i know the fd's are bigger, but i know theyre very light weight. So what can I personally expect. i dont have the sizes and weights for both. If it helps they are the reinfroced fd wheels.

 

ummm...wouldnt the hubs need to be changed? phone dials are 4 lug and FD's where 5......

 

He mentioned that in his first post.

 

lol...good call.

 

phone dials are only 13.5 punds... couldnt find out how much fd wheels are

 

get some rota slipstreams, good looking and very functional, like 12 pounds for 15 inch! and 16 is 13.5!

 

im not a fan of aftermarket rims. I believe in keeping it mazda.