A small single turbo with a difference...

There's been a lot of chat about grip and power lately, and for most people - myself included (when I have the spare £) RLTC is the way to go!

However, my girlfriend asked an interesting question earlier. Since it's nearly always the 2nd turbo that does the damage when it comes online, she said would it be possible just to switch it off? If it could be done electronically then you could have a button on the dash!

It seemed silly, then I thought about it and it's just controlled by valves, would it be real easy to stop number #2 from working - just for those really slippery days? Can it be done electronically?

Why not just regulate your right foot more?

It probably possible but I can't see the point.

Like, on my mates starlet turbo, they come factory with High and low boost button

I know I know, but it's that transition isn't it. Foot set, revs rising and power holding nicely, bam the 2nd is it and the back end has stepped out - as it is, you have to take your foot off just before, wait for it then feed it back in, not very progressive either way!

it was just a thought, she said it from a passengers perspective...

So either run in TTC or have an ETTC mod done. Then you'll find the delivery alot more progressive, the only downside (if you consider it a downside) is the lack of lowdown grunt that you have as the first turbo is locked in with no2 so you begin to make progressive boost at about 2900rpm with full boost by 4000rpm.

In run in ETTC all the time now especially in this weather and I haven't been caught out yet whereas in seq mode i would always spin up at about 80mph in 3rd geat as no2 came on line

ahh ok well I hadn't thought about that option too carefully before.

So ETTC, I take it that is an electronic TTC mod that can be switched as you drive, or have I got that completely wrong? How much would this cost then? Is it easy to fit?

If you know what you're doing is relatively easy. However I had mine fitted.

See here for details of how to do it.

http://www.mkiv.com/techarticles/ettc/index.html

This is why I went single...I don't like the transition either. Single's IMO are more predictable.

of course I'd like a single too, just considering my budget at the mo though, RLTC is first on my list.

Cheers for the link class one, that mod is essentially free then and looks like you can wire it in at the ecu, well I did the Thor VFCD at the ecu without too much trouble so this looks quite easy, a job for when I get some spare time

Like, on my mates starlet turbo, they come factory with High and low boost button

ehh yeah but thats one turbo, hes talkin about switching off one of the turbos at the touch of a button, not setting from high to low boost, completely different so basically nothin like ur friends starlet turbo! lol

front wheel drive 140bhp and rwd 320+bhp,hmm bit of a difference

This is why I went single. Single's IMO are more predictable.

And faster than Hybrids!

Well if you can effectively switch the number 1 turbo off untill much further up the rev range then you should be able to move the second turbo range much further up the rev range as well effectively switching it off. I don't know if its down to the HKS cams changing the whole power delivery but mine just doesn't seem to have this 2nd turbo surge. My aristo however does. Its a bit of a PITA when you've been used to constant power surge from the offset. I find to utilise the power you have to take it high up the rev range and then spend the rest of your time constantly changing gear or initially in my case constantly hitting the rev limiter.

ok but #1 not actually switched off until higher in the rev range is it in TTC. It's just that once set up in parallel TTC, rather than sequential they spool up later, together, making a more progressive boost rise and hopefully safer delivery - well that's the theory isn't it for TTC? that's my limited understanding anyway.

I don't know of any way of moving the second turbo to actually come in much higher up the rev range, don't think that is possible is it unless you adjust the actuator for #2, sounds iffy. I was originally thinking of maybe you just disconnect the valve that starts turbo #2 electronically. I'm liking the ETTC mod idea now, I'd like to at least experiment to see how the car drives both ways and the extra safety in the winter, bonus!

Turbo's have a boost threshold. Unless you restrict airflow the turbo's will come in when they come in.

Using ETTC/TTC is you're only option for more pretictability...otherwise go by an NA.

Well all TTC does is move the No1 turbo up the range so they both spool together. So if you can do that I can't see a reason why you can't move the No2 up the range instead. I'm not sure how the Ettc works so maybe it doesnt work as simple as that lol.

Then try the TTC mod first, see how you like it then install ETTC if you do.

It's a 5 min job and even a numpty like me could do it!

Well all TTC does is move the No1 turbo up the range so they both spool together. So if you can do that I can't see a reason why you can't move the No2 up the range instead. I'm not sure how the Ettc works so maybe it doesnt work as simple as that lol.

Well you can stop the turbo's working all together, it's called a boost leak!! The TTC conversion stops the First turbo getting the air supply it should...instead they have to share, just as they do over 3700...

FWIW I think this is pointless. I've never heard of people wanting to introduce lag before, it's nuts! Try using stock boost that'll calm it....put the cats back in too for more backpressure.

i would always spin up at about 80mph in 3rd geat as no2 came on line

80 mph? You are on a private test track when you do that, right?

Puting the "is it pointless" question to one side for a second, would placing a switch in line with the IACV VSV accomplish what is being asked for? There seem to be a number of "2nd turbo not boosting" threads that are linked to the IACV not opening and thus not spinning up tubby No2.

(check the newbie status in my title and heed it's warning before trying anything I suggest!!!)

Cheers,

Chris.

So either run in TTC or have an ETTC mod done. Then you'll find the delivery alot more progressive....

Are you on drugs? I'm guessing probably not but thought I'd better ask!

In normal operation my number 2 spins up quite suddenly depending on how I'm accelerating, if I've been around high #1 boost for a while it's fine - it only spikes when #2 comes on if I floor it from very low revs and never lift through the range.

With ETTC switched on, no matter how I drive I get NO boost below 4k EVER and the 'spike' introduced as both come online is about a gazillion times worse!!!! First time I did it on a straight road in perfect conditions the wheels spun in 3rd (with 285 tyres remember!!!). I could hear my turbos begging me to switch it off!!!

ETTC is a crock of shite and should be left well alone.

(IMO)

I can maybe understand what you're saying, if you've got an auto car, and you (foolishly) give it too much throttle so it kicks down and brings No.2 turbo online at the same time

But with a manual, you're completely in control. If it's wet and/or slippery on the roads, just keep your foot off the bloody throttle

Things like RLTC are a great backup for when it all goes tits up in an unexpected situation, but to drive like a prat hoping that the TC will compensate for your stupidity, is just asking for trouble with a capital T.

As others have already pointed out, it is possible to alter the wiring to stop one, or both, turbos from working, even to install a switch in the car for ease of use.

My understanding is that said switch is already fitted, and resides under your right foot. Its far more progressive than any on/off variety and is always in the mode you require at any given time

If you want to experiment with power delivery differences between sequential and TTC setups, by all means go ahead, but FFS don't use it as a way to compensate for poor driving skills

We all drive too fast at times, sometimes (mostly) we get away with it, occasionaly we fcuk up big time, but hopefully if we do, we've got the balls to admit "I was driving too fast/with too much throttle etc." NOT "That 2nd turbo just kicked in, and I had no chance" :thumbdown

I can maybe understand what you're saying, if you've got an auto car, and you (foolishly) give it too much throttle so it kicks down and brings No.2 turbo online at the same time

 

But with a manual, you're completely in control. If it's wet and/or slippery on the roads, just keep your foot off the bloody throttle

 

Things like RLTC are a great backup for when it all goes tits up in an unexpected situation, but to drive like a prat hoping that the TC will compensate for your stupidity, is just asking for trouble with a capital T.

 

As others have already pointed out, it is possible to alter the wiring to stop one, or both, turbos from working, even to install a switch in the car for ease of use.

 

 

My understanding is that said switch is already fitted, and resides under your right foot. Its far more progressive than any on/off variety and is always in the mode you require at any given time

 

If you want to experiment with power delivery differences between sequential and TTC setups, by all means go ahead, but FFS don't use it as a way to compensate for poor driving skills

 

We all drive too fast at times, sometimes (mostly) we get away with it, occasionaly we fcuk up big time, but hopefully if we do, we've got the balls to admit "I was driving too fast/with too much throttle etc." NOT "That 2nd turbo just kicked in, and I had no chance" :thumbdown

... Can it be done electronically?

yes.

You'll tap into 3 VSVs: EBV, IACV and EGCV

If these actuators are not allowed to move, the second turbo will not come online.

The trouble is that the first one is online, so if you insist on pushing the revs over 4Krpm you would be overspeeding it, and if you try to redline it you may damage it.

The autobox operation, fuelling and ignition will also be substandard, because they usually assume that the second turbo is operational.

As said though, it's a pointless excercise when you could use your right foot more carefully.

If the road is so slippery, why on earth are you going full throttle, or over 120mph(when 2nd turbo comes fully online in the auto)?

In this weather, I don't do WOT. Asking for trouble. I mainly use ETTC as a fuel saving measure because now I get and extra 80 or so miles from a tank of fuel as a starter.

And as for spinning up at 80mph i did say about and it was only an indicated speed from my crap inaccurate JDM speedo! (ACPO guidelines 10% + 2mph) so I was probably doing about 71?!!!!

As for boost spikes, I'm aware of the potential damage that they can do to the tubbies so keep an eye on my boost gauge and use the excellent traction control feature that links up between my right foot-arse-brain which usually works quite well. The car has only got the better of me once, last year on the way to Rockingham on a roundabout on a patch of diesel at about 20mph! Back stepped out but got it back again!

Each to their own i guess, when the roads dry up I'll be switching back to sequential.

Does switching between TTC and normal not require a little driving for the ECU to catch up with what you've done? I seem to remember reading an article saying that the fueling etc would take a while to adjust to the new setup?