True Twin Turbo Conversion???

He i remember reading about a year ago about something i think the poster called ' true twin turbo conversion ' It was a switch he fitted to make both the turbos to spool up at the same time so you ended up with a harsh surge of power instead of the smooth power the supra produces as standard. Does anyone remember this or know what to do?

http://www.internetwork.org.uk/ettc/ettc.htm

there it is bud

welcome to the club

what do you do if you got an AVC'r plumed in? i tried it before, and it just seamed to stop no1 spooling

are you sure it stopped spooling. when i did it i did notice it had a laggy feeling but was a lot smoother between the two so you may not notice the 1st one because of that!

I thought stopping no1 turbo spooling at 2k rpm was the idea of this conversion?

Where's the guide for it again?

Thats a GREAT link.

Anyone tried it? Whats the verdict?

Scott =op

i think its a love it or hate it kind of thing.

i didn't like it much!

Have you taken it out or do you just leave it switched off? Did you notice a difference in fuel consumption?

I quite like the idea of a switch.

Scott =op

no sorry, i didn't do the switch type because i tried it the vac way and decided it wasn't for me.

that link goes to a site from a member on here but i cant remember who it is!!

heckler rings a bell but i may be wrong

Thanks for the link but im a bit worried about doing this conversion! has anyone tried this? I melted some valves on my supra many years ago when one of the pipes on the valve (vsv???) split and came off. I got a rush of power and more turbo noise. I put the throttle down trying to work out what the problem was and 5 seconds later it split a boost pipe. I fixed the boost pipe still not knowing why the car was making bigger turbo noise ( the split valve pipe) and hammered it again. Under 10 seconds later i was running on 5 pistons and melted valves. Is this a safe conversion or not? I see you reconnect the pipe else where and not to air like mine had gone. Any help please.

try the vacuum way first to see if you like it

http://www.internetwork.org.uk/ttc/ttc.htm

sorry, didn't read all of that.

it works fine as long as its done correctly.

my car is set up like this and i really like it.

if its wet out you can drive it around easy as the turbos dont really come in till about 4k revs

I had it on my car. The switched version is ettc (search it you'll find it here or on supraforums) the non switched is just ttc. I had ettc. I tried it a couple of times and in my estimation it was a load of arse. On a bpu car the first turbo will spool so much quicker that you have full boost very early on. If you then delay that boost to help add to the second turbo's boost you are wasting your time and delaying your cars acceleration effectively introducing turbo lag where you didn't have it. I can see some benefit to a bone stock TT but how many of these are there around here? My car runs a single now and sometimes I really wish I had the BPU delivery that I had with twins.

I run my car like this all the time, and love it, better fuel consumption to, i got fed up with the nothing special first turbo boost coming in to early and then nothing until 4,000 rpm and finding that a let down, but its a very marmite thing;)

I dunno how to answer that. You get lower fuel consumption because you remove fuel from your daily drive. You remove fuel because you remove boost. You are removing boost by running in parallel mode rather than sequential. Basically you are slowing your car down. The 1jz mark3 had the parallel mode as standard and when they designed the 2jz mk4 toyota decided that sequential was a better way to go. I;m not going to argue with men that get payed ridiculously more than I do.

Here's the 5 min mod

http://mkiv.supras.org.nz/articles/andy.htm

Dont you get boost spikes with this? Im thinking of trying this but got put off when i read boost spikes.

no sorry, i didn't do the switch type because i tried it the vac way and decided it wasn't for me.

that link goes to a site from a member on here but i cant remember who it is!!

heckler rings a bell but i may be wrong

guilty

a) You'll need a boost controller to stop spiking to 1.5 bar

b) it's advisable to have the fuelling mapped for this mod.

I did it before going single and love this mod. Also it's very popular with the RX7 lads at the moment. Launches are easier and as already mentioned the fuel consumption is a lot better.

a) You'll need a boost controller to stop spiking to 1.5 bar

As counterintuitive as this sounds, it's true. I know we on here always say you can't lower boost with a boost controller, only raise it, but this is the one exception. The reason being, the stock ECU doesn't let the wastegate open until you are at 4000rpm+, because the boost pressure, in sequential mode, is controlled by the exhaust gas bypass valve to prespool the second turbo. However you can start getting on boost in higher gears well before 4000rpm - and without the wastegate opeining it's runaway boost, hence the spike. The boost controller replaces the stock wastegate controls and functions across the rev range, not just from 4000rpm+, so it stops this boost spike - although in my experience it needs to be a controller that is mappable around what revs you are at. It needs a lot less solenoid duty between 3k and 4k than 4k+ to control the spike and still offer correct boost control in the upper ranges.

b) it's advisable to have the fuelling mapped for this mod.

Definitely yes. The stock ECU does two things below 4000rpm - one, it fuels for a small turbo kicking out 0.7bar of hot air. Two, it runs relatively lean AFRs for economy reasons (14:1). Double up the turbos and increase boost to 1.2bar and the fuelling is really really inadequate and detonation is pretty much guaranteed. I know the "wire it up and let god sort it out" bods might not want to hear that but it's what I've experienced on every parallel mode I've ever been in. Needs about 30% more fuel in round that area than what the stock ECU provides.

On top of that though, due to more fuel and a cooler charge, you can wind on the ignition timing somewhat, which is a bonus

I used to miss the first turbo as well, and going in sequential setups reminds me of just how responsive they are. But then when they get booted from 2000rpm and you wait for the 2nd turbo, and wait... and wait.... I realise I do prefer the big single delivery rather than an artificial lag of 4krpm in every gear.

-Ian

Would a 1.2 Restrictor ring be suficiant for this mod or is it nessesary to use the Boost Controler?

Cheers Cass.

I dunno how to answer that. You get lower fuel consumption because you remove fuel from your daily drive. You remove fuel because you remove boost. You are removing boost by running in parallel mode rather than sequential. Basically you are slowing your car down. The 1jz mark3 had the parallel mode as standard and when they designed the 2jz mk4 toyota decided that sequential was a better way to go. I;m not going to argue with men that get payed ridiculously more than I do.

I was mealy stating my preference, and tell me something i don't know, personally i find the first turbo coming in so early a pain, it promotes wheel spin where you don't need it, especially on greasy town roads, and wastes fuel and i have always driven single turbo cars in the past, so i guess i am used to the power delivery.

Would a 1.2 Restrictor ring be suficiant for this mod or is it nessesary to use the Boost Controler?

 

Cheers Cass.

The restrictor ring works in conjunction with any boost control, so no it wouldn't be sufficient on it's own if you went parallel and in fact the spike would be even worse without the RR in place.

-Ian

The restrictor ring works in conjunction with any boost control, so no it wouldn't be sufficient on it's own if you went parallel and in fact the spike would be even worse without the RR in place.

 

-Ian

Cheers.