Have been wondering, if I drop 100 pounds off the car(weight or rotation mass) + tune which seems to add about 30-40hp + regear, could I likely get acceleration to 4 secs or just under?

My main concern is regearing the car, not much documentation on that. I know someone swapped for the rc 350 3.13 gears but not sure which parts exactly are needed for that or what other more effective regearing options there might be.

Not interested in Supercharger so far.

 

RCF is already a tested 4.1 - 4.2 seconds stock. With exhaust alone (and good launch, good grip/sticky tires), getting high-3s or 4.0 seconds is entirely possible. Here is a thread you would want to read. A full bolt-on + tune RCF makes about 55 whp more than stock (about 70 HP @ crank).

The Ultimate RCF Dyno Thrash session! - ClubLexus - Lexus Forum Discussion

I did a lightweight Lithium Ion battery and I did a before/after on OEM battery vs the battery I have and I lost 30 lbs of weight. If you do lightweight brakes/rotors then you could lose another 35 lbs total rotational mass loss. You don't need to do final drive swap, if you get all of that power from bolt-ons and tune. I have intake/exhaust and soon RR racing tune. It already revs so fast that I slam into rev limiter so quickly that I don't wish for shorter gearing. I always know which gear to downshift to at a given speed.

 

I believe that it is entirely possible with weight loss alone, even more with a tune i think, RCF fuji edition has same engine, not sure if same tune or not though, but saves 150lbs over regular rcf i believe, and its high 3 to 4 flat, so i believe if you follow the blue print of the fuji which is mostly focused on weight loss you could achieve it. Keep in mind that putting your car on a diet will be very costly, so question then becomes is the investment worth it to just knock of a few parts of seconds, per my experience with this car and most that i have owned is we should stop nip picking and enjoy them as is, just my 2 cents.

 

You should look at two piece rotors. You can look at loosing almost 30lb of spinning mass. Every time I've gone with two piece Giro Discs on my vehicles there is a difference that can be felt.

You can also look at lighter wheels. Those two things alone should be a noticeable affect when driving since you are loosing rotational mass. If you have money to burn you could always get a Ti exhaust system from the midpipe all the way back. You'd shave off another 50+ish lbs. Lightweight battery would shave 20-30lbs..etc. Then it would be up to you how light you wanted to try and make the car. It's big anyways so personally I think rotational mass is where it's best valued. I love the hand polished wheels so I wouldn't change them, even though several people here have and reported a much greater weight savings. I'm 100% doing Giro discs shortly. Plus they just look so nice.

-Nigel

 

Power to weight ratio is an important factor. Reducing weight will have some level of impact. The cost trade off for reduced weight is factor that only you can decide. You could spend a lot for upgrades and weight reductions. I would guess it could get expensive real quick. Please keep us informed with what you end up doing

 

How fat is your wallet? Lighter wheels can cost 10K ($US) or more for 4 depending on how extreme you go with carbon fiber--be interesting to have a $ per pound saved chart for weight savings and a $ per horsepower gained chart so you can maximize the gains for your particular pile of dough.

 

I would get a draggy and test the car in its current state. I think you will be in reasonable proximity to your goal. It's possible tune/exhaust and a little weight would break the 3.99.

-Justin
RR Sales

 

I am actually considering headers, are the gains compromised if I were to get UEL or El headers with the stock exhaust? Or is aftermarket exhaust needed for the msot gains?

 

You need both headers and full exhaust to maximize gains. You will still get gains with just headers, but not nearly as much with both of them together. Good thing is, headers give you the best gains so you still end up with significantly more with the stock exhaust. I believe headers give around +30 whp and exhaust around +18 whp so in total 48 whp (or around 60 HP at crank).

 

You will not see any performance benefits with EL over UEL. We probably sell 15 sets of UEL to every 1 EL. But as 05RollaXRS suggested, you really need a good catback to compliment the headers for full gains. 50 wheel hp is the number on a tune, header and exhaust. 15 of those come from the catback.

Here is a link to our RCF dyno session where we made 100 pulls testing many combos.

​​​​​​http://blog.rr-racing.com/news/2022/...-on-lexus-rcf/

-Justin
RR Sales