Small 'singles' questions

1) Will/are all singles be more laggy than stock turbos in parallel?

intuitively i'd think yes, in that they are capable of higher BHP and therefore the trade off is slower spool/more lag, but sometimes on here its said that the smaller ones can achieve good boost low down......

and following on from this....

2) Can you get a single capable of say 380bhp max (ie enabling the use of stock fuel system 'including' injectors) that spools faster than stock twins in parallel.......

Rush i belive is getting a T60 installed on complete j-spec stock fuelling with the addition of a SAFC i think.

Why would you need a SAFC with stock injectors?

Yeah i was thinking that as i wrote. I did suggest stick 550's in while he was doing it all. I'll have to ask him and find out.

Terry's T61DBB produces boost at ludicrously low RPMs and has the capacity to go to 550bhp if you have the setup to cope, so that might be worth considering with a really weedy wastegate spring

The stock ECU does some wierd stuff with a single turbo around 3000-4000rpm because a) it's not expecting such cool dense airflow off a big turbo and b) it is expecting the sequential transition to occur. Some form of compensating for this is a must.

-Ian

Well, unless the "small single" is actually "smaller" than the stock No 1 turbo it will be laggier. As the stock turbos are (individually) very small and make at best .8 bar on just one of them....

Well, unless the "small single" is actually "smaller" than the stock No 1 turbo it will be laggier. As the stock turbos are (individually) very small and make at best .8 bar on just one of them....

Yeah, but for some reason if you run them in parallel, as Scooter mentions, they take forever to spin up - they only get on song at about 3500+ rpm They only supply 0.8bar up to about 4000rpm anyway, above that if you are stuck on one turbo due to a sequential system fault you really know about it...

-Ian

Well, in parallel they take much longer to spool than a comparatively flowing single for a very obvious reason

 

The stock ECU does some wierd stuff with a single turbo around 3000-4000rpm because a) it's not expecting such cool dense airflow off a big turbo and b) it is expecting the sequential transition to occur. Some form of compensating for this is a must.

 

-Ian

But b) occurs when the stock twins are in parallel and no one advises any form of compensation then.......or do they?

if a single is used that mirrors the performance of the twins can you 'get away with it'......

.....if not are we talking a simple fuel compensating device ie lower tech than emanage etc......

Well, in parallel they take much longer to spool than a comparatively flowing single for a very obvious reason

so can i assume from the above that a single capable of the same max BHP (say 380) as the stock twins will spool up quicker than the stock twins in parallel........

BTW thanks for the input chaps.....

so can i assume from the above that a single capable of the same max BHP (say 380) as the stock twins will spool up quicker than the stock twins in parallel........

 

 

BTW thanks for the input chaps.....

Possibly. The manifold design is poor, it's a compromise forced by sequential operation and packaging. However, a single turbo capable of efficiently supporting 380 BHP will not spool as fast as the first turbo of the sequential set up working as Toyota designed it to

The stock ECU does some wierd stuff with a single turbo around 3000-4000rpm because a) it's not expecting such cool dense airflow off a big turbo and b) it is expecting the sequential transition to occur. Some form of compensating for this is a must.

 

-Ian

I noticed this when running in (E)TTC that when you get to about 3600rpm (transistion point) there is a momentary drop in boost despite being in TTC as no2 kicks in. Would that happen if a small single was fitted. Ie the stock ecu will still act as if twins are fitted in seq mode as they do in TTC?

(Sorry for the thread hi jack.)

I noticed this when running in (E)TTC that when you get to about 3600rpm (transistion point) there is a momentary drop in boost despite being in TTC as no2 kicks in. Would that happen if a small single was fitted. Ie the stock ecu will still act as if twins are fitted in seq mode as they do in TTC?

 

(Sorry for the thread hi jack.)

IMO the stock ecu is totally and utterly unsuitable for running a single turbo, as it is for running none sequential twins. The ignition and fuel maps are nothing like those required for a single. Fudging them is just that, a fudge.

I'd have to agree - I've run parralell for 6 months with Emanage and am going back to sequential - it's does some funny stuff in the middle, and I might as well have a single for all the lag. The noise is unbearable too - reallly resonates at 3-4 - that's bang on 72-85 mph in 6th - so you have to drive in 5th on the mortorway - or sit at a ton!

I'd have to agree - I've run parralell for 6 months with Emanage and am going back to sequential - it's does some funny stuff in the middle, and I might as well have a single for all the lag. The noise is unbearable too - reallly resonates at 3-4 - that's bang on 72-85 mph in 6th - so you have to drive in 5th on the mortorway - or sit at a ton!

Well sit at 100 then

Well sit at 100 then

I tried that.

Surprising, but even at 100 my paranoia overtook me!

am i missing the point here, why would you want to go to the trouble of a single install that isn't going to produce any more (or very little) power than a bpu twin set up, all it will produce is loads more lag than a sequential set up and like Ian C says give you the head ache of getting round the 4000 rpm switch over point

Yah, it seems like a strange plan tbh but I'm not gonna diss it immediately.

That was long enough I've already said parallel stock twins are a load of old poo, the only person I know who got any real results out of it was hong kong Nic, and that's because he put the effort in, got an E-manage and some crazy asian tuners to remap it around the parallel setup. We had an in-depth discussion about this and got some before and after dyno charts and I did try to highlight just how shite going parallel really was if you did no supporting mods. People still do it though Find attached the dyno chart with both parallel and sequential curves on it... Enjoy your 200rpm that's better than sequential, and enjoy your 2000rpm that's a whole lot worse (and a nasty boost spike in some cases too).

The boomy exhaust is also an issue. The only good thing I've heard is it saves fuel, but that's because your Supra now can't make boost until 3500rpm

The sequential system, when it works, is a fantastic design. If you aren't going for any more power, why mess about with it? And if you are going for more power, stick a fatter single turbo on than a salad eating 380bhp one

-Ian

Here's my dyno, I get positive boost at around 2900-3000rpm. The thing I like about the parallel set up is the liniar power delivery, yes I lose a little power low down, but mid rev range I think I gain a bit over the sequential set up and unless you're doing traffic light racing, mid range is where you want the power IMOO

As for saving fuel

am i missing the point here, why would you want to go to the trouble of a single install that isn't going to produce any more (or very little) power than a bpu twin set up, all it will produce is loads more lag than a sequential set up and like Ian C says give you the head ache of getting round the 4000 rpm switch over point

The reason is simply a cost one........i have stock ceramics on the lexus and if/when they went i'm not sure what i'd do.

Stock twins are expensive, used ones are a (big) risk so i was just wondering if small single was better than hybrids (which are seemingly more prone to failure from accounts on here) or stock steel replacements.

Big singles not really an options as costs above and beyond the turbo kit ie decat pipes, exhaust, ic's etc etc are even more than for the supra.

A T57-61 will out spool parallel stock twins. Once you've gone single you can chop and change turbo's on the T4 flange. A T57 wouldn't be a cheap option....there are no cheap options!

Here's my dyno, I get positive boost at around 2900-3000rpm.

I get at least 1bar at 2200rpm (could be 2000rpm, hard to tell with the torque converter as it's an auto)

The stock sequential can push a LOT of air at low revs if treated properly.

As for saving fuel

Mpg is even worse if #1 is boosted. Can't have everything...

I can't understand why someone would buy an engine that can build boost from very low and then go ahead and dump all that torque in exchange for *nothing*

Big single - yeah! you trade off low-down pull and complexity for a big kick and simplicity. That I understand.

The reason is simply a cost one........i have stock ceramics on the lexus and if/when they went i'm not sure what i'd do.

 

Stock twins are expensive, used ones are a (big) risk so i was just wondering if small single was better than hybrids (which are seemingly more prone to failure from accounts on here) or stock steel replacements.

 

Big singles not really an options as costs above and beyond the turbo kit ie decat pipes, exhaust, ic's etc etc are even more than for the supra.

Well, really there is no silver bullet here to be honest. If your turbos go you are looking at a fair wedge of cash for whatever route you go. I'd go for 2nd hand stockers off a low mileage car that have been stored properly if possible. Richard Harmon bought my stockers off me about 2 years ago and as far as I know they are still going strong

-Ian