05RollaXRS

RCF: intake, headers, tune and 4.08 gears
Supra: Tune, intake, downpipe exhaust

Not sure why he has 4.08 gears as it hurts high speed acceleration and way too short, but good to watch anyway.

tekjunke

Nice! thanks for sharing.

cvt

So crazy that the Supra is rated at 335hp when they dyno so much higher.

Was expecting the RCF to crawl ahead but good on the Supra to hold it.

vbb

iTrader: (3)

Clearly I haven't been paying attention, but I've not heard of anyone regearing an RCF. I wonder why that was done?

05RollaXRS

I believe, he put the 2IS IS350 final drive in it. The ISF guys have been doing it to get better partial-throttle response/torque and it makes the car a bit faster at low speeds. However, it is well known the acceleration suffers at high speeds because you are closer to the overdrive gears.

MoarLow

iTrader: (2)

No contest. Supra can get tuned for much cheaper than an FBO RC-F. MHD tunes goes for about $400 for a stage 2. Downpipe and spark plugs are cheap. Intake and exhaust won’t do much.

05RollaXRS

As stated, Supra has a tune on it and mickey, which I believe he means mickey thompson slick racing tires. The RCF is not FBO either since it is on stock exhaust. Just headers and intake with RR tune. It is a run-what-you-brung.

Though, I agree if you go all-out on the Supra, a turbo inline-6 engine will always come out much ahead as there is only so much one can do to a high-strung N/A V8. The cap is 460 - 465 whp.

ProMover

The RCF looks like it has an aftermarket exhaust though. Aren't those some burnt tips sticking out the back?

05RollaXRS

Yeah, they are burnt blue tips. It was not mentioned in the list of mods, but yeah at least the tips are not OEM.

cvt

Caps?....ain’t nobody got time fo dat!....lol

https://www.rr-racing.com/RR-Racing-...rcfscr1001.htm

05RollaXRS

LOL true. I meant, naturally aspirated.

lobuxracer

iTrader: (2)

The math does not support this contention at all. One thing matters - where are you in the engine's powerband? At high speeds, it's very easy to be in the thick of the powerband, so gearing is inconsequential.

vbb

iTrader: (3)

In cars, like the Porsche Cayman GT4, that have gearing that is way too tall, I can understand why people regear. Until this thread however I had never heard of anyone complain of the RCF's gearing ratios and especially not to the point of going through the hassle of swapping out the gears. It seems like a very strange mod to do for this car and I'm curious as to what the person was attempting to achieve. I take it the owner of the car is not on the forums because I'd love to hear his reasoning.

05RollaXRS

RCF gearing feels quite tall for its rev range, which is very wide. 2nd gear ends at 119 KM/H and 3rd goes to 100+ mph. Initially, I was turned off by the fact that you cannot use much of it in city driving, but I have "learned" more about how to use the powerrband more in sport+/manual. I came from my Corolla XRS, which could get to redline 3 gears easily while merging on to a freeway. at 75 mph or so. In RCF, by the time you get to redline in 3rd hear, you are doing 110 mph or so. Using paddle shifters to downshift every time the speed is dropping. That way, even at slower speeds you are in the higher rpms. Also, the full exhaust has also helped by adding a lot more sound everywhere in the rev range and also made the car more lively with added torque/HP. On the highway, for instance if I wanted to get into the left lane and pass a few cars, I would downshift to 2nd instead of 3rd at around 70 mph or so. That way, I can play with 2nd and 3rd before letting off.

Now, as I have understood it more, I have grown used to the long gearing. Also, the exhaust has helped immensely. The 2020 RCF shorter gearing is nice (from 2.97 to 3.16), but I think most people would not notice a difference. Another easy way of playing with the gears is by trading some circumference for some more width. For example, going on the rear from 275/35/19 to 295/30/19. That will give you more width and shorter overall circumference, which leads to overall shorter gearing. That is a much safer and cheaper way to get shorter gearing without taking the whole differential out etc.

lobuxracer

iTrader: (2)

With 8 available ratios in the gearbox, the differential gears are only impacting how long it takes to get into the meat of the power in 1st gear. After that, it's pretty simple to stay on the boil and apply the most power you can. Shorter diff gearing will get you to the bottom edge of the powerband more quickly, and that's when the party ends. If you are drag racing, that might be important. Anything else, not so much. A lot of this is just like brake pads - a high friction pad will feel like you are stopping more quickly because you put less effort into the pedal to get a much more aggressive response, but the reality is, in a panic stop the pad's friction is unimportant as long as it can lock the wheel, and just about any pad will do this, even the super cheap ones.

I had a long drawn out argument with a good friend over this exact subject when I was considering putting lower differential gears in my IS F. He said it wouldn't make a significant difference, then pulled out the math to prove how right he was. If we only had 3 or 4 gear ratios in our transmissions, differential ratio selection is far more critical, but as the number of gears increases (approaching CVT), the less important the final drive ratio is.