c0rbin9

iTrader: (2)

I have driven several stock FDs and they all require a big, deliberate blip to match revs when downshifting. Much more than naturally-aspirated cars and even some turbocharged cars.

Curious if anyone else has experienced the same thing, and whether intake/exhaust would improve response.

Manny_Apex

iTrader: (1)

The biggest difference between my RX-8 and my RX-7 is the stock DBW in the RX-8 vs the cable throttle in the RX-7. Now I have a lightened flywheel in my RX-7 so the difference is probably less noticeable than stock FD's, but that would be my guess.

gracer7-rx7

iTrader: (16)

Agree with light weight flywheel and possibly tuning

GoodfellaFD3S

iTrader: (213)

From memory the factory FD OEM flywheel is extremely heavy, like 23 pounds. Every FD that I own gets a lightweight flywheel at the earliest opportunity

c0rbin9

iTrader: (2)

Thanks for the replies y'all. Lightweight flywheel makes a lot of sense, only reason I bring up intake/exhaust is because someone mentioned it making a big difference in an older throttle response thread.

BLUE TII

iTrader: (9)

Tuning.

I already had lightweight flywheel, intake, exhaust, disabled the throttle dashpot (revs fall faster) and abled/disabled the double throttle (no change).

Then when I put in the Knightsports ROM tuned ECU the throttle response got much better.

I imagine they put a heap of timing and fuel in the low load cells to help throttle response.

I was finally happy w/ FD throttle response.
Had to blip the throttle between up shifts (not revmatching downshifts) to bring the rpm back up. Thats how good the throttle response was/how poorly the FD transmission shifts.

Haha- I have a feeling that one wont be any easy fix, though I have a brand new Mazda trans waiting to go in.

Sgtblue

iTrader: (16)

Use care going with a lightened FW on a street driven car. I’m happy with mine, ((IIRC, 11 lbs w/o counter-weight) but I think it would be easy to go too light.

arghx

iTrader: (3)

When people say "throttle response" they mean different things. Some mean the level of G produced after hitting the gas pedal, which takes into account n/a torque, and the way the engine builds boost. Other people mean how quickly it revs when the car is in neutral or with the clutch pedal depressed.

What vehicles are you comparing it to? Did if they have electronic throttle? Were they stock? The design of the throttle linkage is part of it. Just like a modern electronic throttle car has pedal mapping, throttle cables have pedal mapping too, but they are fixed characteristics of the throttle linkage design. So an FD for example has a two stage throttlebody that opens the primary ports first, and then the secondary ports as you put the throttle down more. That can contribute to the feeling of needing to hit the gas pretty hard to rev the car up. An Rx-8 has electronic throttle and controls the secondary ports with a separate valve that is mechanically unrelated to the throttlebody.

Stock flywheel is 19 lbs for the FD vs 23 lbs on the FC (I just Googled it). Google also tells me that a Civic Si of that era had an 18ish pound flywheel. My V8 Challenger had a 24 pound flywheel.

The stock flywheel of the FD is very light and the car revs and stalls easily if you compare it to a modern car. Compared to my manual challenger or manual mustang it's much more free revving. Also when you lighten the stock flywheel on an FD you typically can increase your risk of stalling on decel. I'm not saying there aren't work arounds to that, but the FD is a hard enough car to drive as it is, if you've regularly driven anything manual from the past 15 years.

DaleClark

iTrader: (55)

There's a lot of things that can change how the throttle feels.

First is the cable. If the cable is worn out and has a lot of friction inside the sleeve it moves it, that will increase the effort. If it's adjusted at the throttle body poorly you could have a lot of slack in the cable that has to be taken up before the throttle plates actually move. I've also seen dumb stuff like a floor mat all wedged up under the pedal that bogged it down (which is crazy unsafe too).

Second is the TB itself, if it's gummy and sticky it may not open as easily as it should.

Third is tune. A good tune and the car running properly goes a long way. Good spark plugs, good spark, healthy engine, healthy electrical system. With an aftermarket ECU having a good tune and it set up well is huge.

Finally is the flywheel, going with a lighter flywheel can change how the car feels as it revs up and rev-matches.

Dale

j9fd3s

iTrader: (3)

engine mounts make a big difference too, although there is an NVH penalty for going stiffer

Neo

iTrader: (4)

In general, modern day vehicles with e-throttle are a total PITA to make proper rev matches when you’re downshifting. That’s just the way they’re designed. Not sure why though.. probably has to do with fuel efficiency.
As far as I’ve seen, nothing matches naturally the way a cable operated throttle does. Regardless of vehicle.
By simple comparison, rev matching with my 8 compared to the 7, I have to push the throttle down harder and further in the 8 to get the same result I would get just barely touching the throttle on the 7.
Before everyone says tuning will fix that, I doubt it. I had a tune on my NC Miata and it was slightly worse than the regular mapping on the 8. Benefits of the rotary and it’s willingness to rev. The Miata engine, despite having some bolt ons, comes nowhere near as rev happy as the rotary. That’s just the way things are.
However, in terms of throttle response, the mechanical throttle on the 7 is a thing of beauty. So much more feel and natural instinct compared to these e-throttle pedals.

neit_jnf

iTrader: (17)

ACT Pro-lite flywheel may be too light for street imo. It stalls sometimes before the PFC catches it at idle and I've failed at adjusting it.
But I also have a port matched UIM with double throttle removed and a RC Engineering big bored throttle body so idk...

Manny_Apex

iTrader: (1)

Honestly just depends on the person. I've been fine with it for the most part, whether canyon carving or going to the grocery store. The only time I really struggle with it is the school zone on base. At 15 mph in 1st gear, buckle in cowboy because she's a bucking bronco.

j9fd3s

iTrader: (3)

i put mine on a scale and its not light, i think its only a couple of pounds different than the stock one.

the PFC can be a PITA, but if you haven't changed the FC settings to 1180, you should. it seems to be a magic number, and then the idle speed setting needs to match the actual idle speed, or the ECU gets cranky.

Sgtblue

iTrader: (16)

It’s not always just the weight but where it’s located on the FW. If the mass is closer to the center (w/the counter weight) I think it makes a big(ger) difference.

Thanks for the PFC tip…it’s been along time since I’ve changed anything…I don’t really have any issues. But I’ll have to check things.

j9fd3s

iTrader: (3)

its kind of off topic, but if you unplug the BAC and turn off the idle timing in the PFC you get the mechanical idle speed, and the idle setting in the ECU needs to be higher than that, or it does weird things

for example my car with the idle controls off/disconnected would idle around 760rpm, and setting the idle speed to 780 fixed just about everything. turns out i had a leak(s, seriously my throttle body is like a colander), and fixing those dropped the idle more, but i have the lighter flywheel, so 770rpm is a little nicer imo.

stealth fuel saving tip too, lower idle = better fuel consumption.

DaleClark

iTrader: (55)

For what it's worth IMHO light flywheels are $100 worth of cool that costs $400 and a pain in the *** to install.

If you're in there? Sure, go ahead and do it if you have the money. It is neat. But it's not life changing.

If you have a PFC and have problems with stalling FC-Tweak can help that out big time, he's figured out how to do good "fake" dash pot.

Or just having a real working mechanical dash pot. If you don't have one or it's bad you'll have stalling, even on a stock car..

Dale