ok...theres stipulation once again with my driving, i dont kno whos wrong or whether whos right...but is downshifting in any gear bad for t2s? or any turbo cars? cuz my friends are tellingsome stuff about boost surge when the rpms jump up or something like that...but something about downshifting they said is bad with the turbos and ****. but whats right..and whats wrong? thanx

 

I heard something similar from TurboGXL (someone told him this) and I wanna know if that's true or not. Doesn't make sense that it would be bad, unless it's done recklessly. I have the RX-7 book by Yamaguchi (sp?) and one of the co-authors was talking about driving the thing around the Nurburgring. I highly doubt that he didn't downshift the car (it was a turbo) driving it around that track and there was no mention of any danger doing so.
I've heard that downshifting hard into first will mushroom the brass retaining ring on the synchro (is this right TurboGXL?) and make it difficult to put the car easily into first gear. But I've heard that about alot of cars, not just the REX. There's some smart dudes on here and I'm sure one of em knows the answer.

 

I think that downshifting any car and especially high powered turbo cars from say 5th gear to 3rd gear on the freeway is hard on it- but driving hard is part of having a performance car to me.

Drag launches are very hard on the car and it doesn't stop people from doing it...

I read a letter to an editor once about a guy complaining his turbo kit-ed Civic blew up when downshifted to 3rd on the freeway and then redline shifted up. The Ed. said pretty much "well, duh that is very abusive what did you expect." Lucky for us our TIIs can take alot of this abuse.

 

I happen to think that we're pretty lucky with our wide powerband and high redline. If you're paying attention to what you're doing you shouldn't throw the car into a situation where you're over-revving the engine. I would also think that since these cars came from the factory turbo'd that you wouldn't run into some of the problems that are inherent with turbo'ing an NA car. Alot of the Honda guys just run out and slap a turbo on thier car without thinking about things like metal head gaskets, lower compression pistons, fuel requirements and the like. I've ran into alot of people that have blown thier engines (and learned stuff the hard/expensive way) because they didn't think ahead.
In fact... a guy I know with a civic did just that... he blew his head gasket when he downshifted from 5th to 3rd and stomped on the gas. Turbo boosted and BAM! 'Course he was upping the boost alot and not compensating for the increasing amount of air (and rapidly lowering fuel/air ratio).

 

I don't get it. Heavy compression braking puts stresses on piston engines, I assume rotaries too. But downshifting and accelerating... why would it be any different to accelerating? I still don't know enough about these rotes to comprehensively say it's bollocks, but unless someone can actually come up with a decent factual reason then I really wouldn't worry about it...

Charlie

 

Downshifting and accelerating does provide INSTANT boost, especially 5th to 3rd w/ open intake and exhaust. Your engine goes from producing 0 to 200+hp very quickly w/ this sudden boost onset. This puts mechanical shock on internal components and drastcally changes all the variables the computer/sensors depend on to run the proper fuel and timing maps, so there is a good chance things are not optimal until engine management can "catch up".

At least this is my understanding.

 

I like to downshift in my TII. But I will rev match my down shift. So if your a passenger you could not tell by feel that I have downshifted. The clues are my hand movment and the engine noise. I have downshifted to first gear from second at about 20mph at autox. I rev matched that.

But if your going down a hill I suppose brakes are much cheaper than engine and drivetrain compenents. So, hell I guess I should ride the brakes down a hill cause those pads come out quicker than a freaking engine

James

 

I do the same thing - done properly, it's very smooth. I just tap the gas, downshift into the higher rpm point and gradually give more gas. You're in the meat of your torque band, so you don't need to mash the pedal.

 

Yeah, I always rev-match as well. If my passenger could feel me shifting then I'm not on the ball! Besides... it's good practice for when you gotta heel-toe it!

 

when I downshift on the highway from 5th to 3rd I match the revs and gradually let the clutch out. as soon as it is engaged I hit it then, and pass the slow people by. With turbo 5th gear is strong enough for passing, but when you get those passive aggressive that speed up on you have to downshift

 

It depends on the hill, if you're on a long incline in the mountains, you realy do want to drop a gear or two rather than sit on the brakes, because you can fade them without realizing it, and then you discover that they're gone as you approace a switchback...

 

whenever im cruising around town i never downshift. if i have to brake i always throw it in neutral and slow down with the brakes. the only time i really downshift is to pass or to speed up for some reason. but then i almost always rev match before i do it. i didnt know that downshifting was really bad for the engine, i just always thought that it was alot of unecessary stress on the clutch.

 

yea, i rev-match too, it is better for your trans and clutch

 

Try an HKS, Blitz, GReddy or other Turbo manufacturer's SSQV (Blow-Off Valve). Relieves pressure surges between shifts, sounds cool, and makes your car more reliable when driving it hard. Cheap too.

 

That's the biggest load of BS I've ever heard. Your friends need to learn a bit more about engines and turbos than they picked up on TF&TF. For starters, the throttle is closed, so no boost or surge is even possible. Even if you're heel-toeing the blip on the throttle is tiny. Um, no. Your ECU can think considerably faster than you can. You put you gearbox in neutral every time you brake? Man that's crazy. You're worried about clutch wear but all you're doing is putting all that wear onto the brakes instead. Engine braking is basically free. Not using it is silly. It's not, it's a normal part of driving a manual gearbox. Modern ECU-controlled automatic gearboxes even do it for you!

These "downshifting" threads seen to come up quite regularly, and I scratch my head every time at the mass confusion and ignorance out there. Like I said, it's a normal part of driving a manual gearbox efficiently. I always enter a corner in the gear I want to be in as I exit, whether on a racetrack or turning into my street. And if you are worried about wearing out the engine and clutch, why'd you buy a performance car just so you could drive like a granny?

 

Yeah Nz what you said.

Me myself I always downshift it is just the way I learned to drive. I never go from 5th to 3rd though I will go 5th-4th-then 3rd but that is just me. And for some reason my car won't go into 1st until almost at a dead stop now I can force it into gear but I don't like the sounds it will make.