IcarusX8

I dont know about that, but I always engine break anyway.

Rumboo

Engine braking shouldn't burn more fuel, cos you're not injecting more than idling fuel when your foot is off the accelerator. You're just using the resistance from your engine's compression to slow down.

However, if you're blipping the throttle while downshifting to save your syncro, and are crap at it like I am, then you would be using a little more fuel. Also, when you engine brake, if you slow down too much then have to accel a little to reach the stoplight, then that's also using more fuel.

psionix

Can you elaborate abit on the downshifting to save syncro part? What do you mean by being crap at it?

I always have this notion that if the rpm is high, more fuel is burnt.
I normally downshift to slow down (resulting in higher rpms) while using a little bit of braking to "save" the brakes.
Friends I have simply drop to neutral and apply the brakes or just apply the brakes alone.

RotoryMadness

When I went to buy my 8 I looked at many cars. Test drove them all from Mustangs, to 350Z's. Top pix's
RX8 Of course
BMW M3
C6 corvette
350Z
The 8 won because of the styling inside and out. Handling, it's a drivers car often equaling cars with more horsepower on a closed course ie. 350Z and BMW M3. The car has one of the best chassis around. And it's not a economy or mid-size family car with a overpowered engine ie. Civic si, or STI.
Now I'm not knocking these cars, my personal pref. I want a sportscar that was built from groune zero to be a sports car.

Rumboo

ohh, i see my sentence has double meaning... sorry!

"While downshifting, if you're blipping the throttle to save your synchro, .."

gotta rush off to work, otherwise 200 passengers will curse and swear at me... more on that later!

lootster

What i understand from a advance driving instructor is that more drivers tend to use engine brake more then their foot brake in order to save thier brake pad which is ironic ......as cost of repairing gear box wear and tear is very much higher then replacing brake pad.
Brake pads are meant to wear in order to stop the car so just use them

Rumboo

If the high rpm is because you are using the accelerator - ie, injecting fuel to move the car, then more fuel is used. If the high rpm is a result of the inertia of the moving car turning the wheels, with the new gear ratio translating that into faster crankshaft rotation and higher engine rpm, then all that energy is coming from the kinetic energy of the moving car, not the fuel.

In hybrid cars, regenerative braking is, in effect, engine braking, where the forward motion of the car is converted by the electric motor into electricity, thereby slowing down the car. While this actually generates useful power in the electric car, this energy is simply wasted in an internal combustion car, but at least we are left with the other useful effect of slowing down.

Eggshell:
Hi rev w/ accelerator = more fuel
Hi rev w/out accelerator = idling fuel


When downshifting, if you release the clutch without revving up the engine while the clutch is depressed so that the gearbox internals match the wheels, you will feel a jolt as the two synchronise. Your synchromesh is doing that job for you all on its own, hence, greater wear on syncromesh. To avoid this, either get a VW/GT-R DSG gearbox ( ), or do the double-declutch procedure (shift neutral, blip throttle, then downshift)

In other words, you know when you release the clutch after downshifting (w/ foot off the accel) and the rpm goes up to a certain number? That is the rpm you want to rev the engine to in the first place before you release the clutch in your new gear position.

If you don't want to bother with double-declutching, you can just blip when the clutch is in, and release the clutch in the lower gear you want. Your synchro will still have to do some work, but at least it just has to fight against the inertia of just a few gear cogs, rather than the entire inertia of your rotors/pistons, crankshaft, etc..

2 things:
First, you will need to blip the accel rather than apply sustained revs, so that the car will actually slow down once the clutch is released, ie, the revs must be falling when you reconnect your drivetrain at the precise moment it reaches target rpm. Otherwise, you would just be maintaining speed.
Secondly, because of the time required to operate the pedal and gearshift, you will need to blip slightly higher than the target rpm so that the first point I mentioned can be carried out. How much higher depends on how quickly you can shift and re-clutch. If you are slow, you need to blip higher.

If you do it right, you will achieve effective engine braking with a lower gear without the uncomfortable initial deceleration which you get when downshifting and re-clutching at idle rpm. In fact, you won't even feel anything except a smooth constant decel.

This is effectively the toe-heel technique, except that for the toe-heel, you're braking with the brake pedal at the same time. In a race, this is advantageous because you're in the correct gear, within your optimal power band, and ready to accelerate immediately as you exit a bend. Also, you won't jolt the car and upset the balance while downshifting, cos it's so smooth (when done correctly).

Any gurus are most welcome to correct my misconceptions... quickly, before i destroy my transmission!

PS: this is not thread-hijacking, cos the OP brought this topic up!

Rumboo

If you can double-declutch perfectly each time, then you definitely save the brakes and won't wear out your transmission, but how many of us can do that?

I think it's more for conserving your brakes during a race rather than daily driving. Also, they say keeping your car in gear will help with controllability, but again I think that's more for racing..

Also, our rotary doesn't engine brake as effectively as a piston engine.

psionix

@Rumboo, thanks heaps for such a detailed and long elaboration. Since you mention that the rotary doesnt engine brake as well as a piston, might as well just save the trouble of messing up the syncros and just use the brakes. lol

All these times I had been engine braking without heel-toeing. Bad. Think I shall do the (shift neutral, blip throttle, then downshift) procedure next time. But blipping the throttle means using more fuel. hahahaha.

So its like i am in gear 3,
foot off accel, depress clutch
shift to neutral, blip throttle to ideal rpm (is the clutch still depress or I release?)

I presume I should release since its called double-declutching right?

depress clutch again and downshift to 2
release clutch

Am i doing it right?

Rumboo

Close... i think it's :
foot off accel, depress clutch
shift to neutral, release clutch
blip to ideal rpm + a bit more, for reaction time
depress clutch, shift to 2, release clutch

in other words, blip should occur while clutch is engaged, but gear is in neutral.

i may be wrong, cos i'm self taught, but it seems to work for me.. check out this video in slow motion and see if it looks like that's what the driver is doing.

http://www.teamsmr.com/movies/Footbox%20Small.wmv

takes a bit of practice, though! Start without heel-toe first. Overrev, and the car actually accelerates when you finally re-clutch. Underrev (or shift too slow) and the normal engine-braking jolt occurs. I just try it for fun.. something else to play with in an MT

psionix

thanks for the link. it helps loads in explanation.

muscleman

RX8 and the Sti is totally different. One is NA and the other Turbo... How to compare...

RX8 is a drifter car with killer looks... Sti is a sprinter with a design you either hate it or love it...

I had driven RX8 before and now drives a WRX. I still prefer the sleek design of RX8 but I love the power of WRX.

Coupe 07,
Do you sell the latest VSD X concept?

littletonysg

rx8 is also a sprinter depends how u mod it, anyway all cars are sprinters. its whether u got the iron b**ls or not.

CoupeM

Er...how is an sti a sprinter when there is a huge lag while waiting for the turbo to spool?? I thot u getting cibic type r how come now get wrx?? hatchback ah?

psionix

hmmm, i tot turbos are pretty well made today that the spooling doesnt take long? But its true that in the STi, you can really feel the eyes being sucked back into the sockets. Not too sure if its because your eyes cant take the ugly interior or not thou :P

I just found my first job. The pay is decent so my RX8 dream isnt too far away. Yeah! Hope I past the medical check up today

muscleman

07 WRX (sedan). Hatchback very slow. Civic type r slower than Rex. Rex has more potential for modding and best of all modding is cheap...
I have test driven the type R, it is not as fast as wrx and very uncomfortable. My wife does not like it. What to do?

Turbo lag? yup, a bit. But once the Rpm is above 3K, it is damn fast.
5.9sec from 0-100.

muscleman

The interior you can always give it a make over. I have give my WRX exterior carbon-fibre treatment and interior cubic-printing treatment. Beauty lies in the eye of the beholder.

You might as well wait for the new facelift RX8, it is much nicer and I believe they have sorted out the common problems of RX8. I hope so...

Unless they come up with a supercharged RX8, then I will buy RX8 again.

Why not consider other cars such as hatchback? Golf GT or GTI? best looking hatchback around? or wait for the Lancer hatchback ralliart with twin clutch sst, 240 bhp and 343 Nm torque?

CoupeM

eh muscleman..welcome to the subaru club...i oso driving wrx...sti...kekekeke...but we all in wrong forum. :P

muscleman

I thought you are driving a RX8 or a hyundai???
I'm here to see whether got good lobang on DEFI... and to read interesting posts.

CoupeM

me???
no ah...all along my real car is a vios. hahahahahahaha

muscleman

And you lost to SSS? You deliberate let SSS win, right?

psionix

Yah I did try to consider the Golf GTi, but its much more exp then the 8. The reason why I compare the CTR, RX8, and STi, is because they are all around or less than 100k.

CoupeM

vios veri slow leh plus i gt weight penalty. help me tia the sss leh. he stay in punggol...

virus

Hi Bro,

Depends what you are up for ...my point of view:

Looks- nothing beat the RX8, looks cool, babe magnet, handling wise ok..50:50 distribution, especially the new design looks cool...

Tracking - Trust me CTR kick ***....and bang for bucks..the stock suspension beats all other brand...i can't remember the link, Tsuchiya (drift king) was testing a CTR with different brands of suspension on the track, Participants like aragosta, cusco, tein, ohlins etc...all the track timing lost to the CTR with Stock suspension.

Powerwise- No doubt among the 3 cars, STI 300Ps, if u are able to get the STI 2.0L JDM spec 310ps with 8500rpm redline, twin scroll turbo. Local STI 2.5L single scroll turbo.

Hope this helps

littletonysg

supercharged rx8 already have, onli u never see properly. btw u in the wrong forum, wrx forum not big enough ah