Sequential twin turbos vs simultaneous

[Ian C]

my turbos are spooling by 2,500 RPM and on full boost by 3,200 RPM, midrange response is better fuel consumption is far better, and turbo response is strong but smooth, no more waiting for 4,000 RPM until you can make decent boost

 

You wouldn't happen to have any datalogs or anything of that, only it's a rather different story to what anyone else who's gone TTC says and either you've done something special that everyone would benefit from or your arse-dyno is lying to you

 

-Ian

[heckler]

You wouldn't happen to have any datalogs or anything of that, only it's a rather different story to what anyone else who's gone TTC says and either you've done something special that everyone would benefit from or your arse-dyno is lying to you

 

-Ian

 

you can datalog mine if you want and then map it too

[Nic]

In TTC mine started to make positive boost around 2800-2900rpm, peak boost around 4k.

[tbourner]

Maybe it is just a case of resetting the ECU and running it for a week.

I always thought the ECU learnt within about 5 minutes of driving though.

[Tricky-Ricky]

You wouldn't happen to have any datalogs or anything of that, only it's a rather different story to what anyone else who's gone TTC says and either you've done something special that everyone would benefit from or your arse-dyno is lying to you

 

-Ian

 

I'll see what i can do;) obviously boost v RPM has a lot to do with engine load so it depends on what gear your in etc, all i have at present is a RR graph, will post it later or you can find it on my RR post, the only one that has a boost figure is the one i did with the bung still in, which robed me of 62 BHP and i would guess boost but if you look at the graph it will show 0.8 bar at 3,500 and thats with dyno loadings ie fourth gear,

i will have to ring SRR and see if they can mail me a full power graph with the boost on,

ass dynos can lie, but two boost gauges generally dint:p

[Tricky-Ricky]

Maybe it is just a case of resetting the ECU and running it for a week.

I always thought the ECU learnt within about 5 minutes of driving though.

 

AFAIK resetting the ECU will only reset the timing to suite the petrol grade your using but advancing or retarding the ignition should it detect knock, AFAIK it doesn't have two fuel maps?

[tbourner]

No but if you're not making any boost at 3k suddenly, the ECU will have to reduce the fuel going in and therefore it will 'learn' to use less fuel at 3k in future?

Not that this helps with making any boost of course!

 

I assumed that the particular VSVs that were modified (I don't know the actual mod very well) would cause both turbos to be allowed to spool at the time when no 2 would have come online before the mod? So therefore in a higher gear (4th for example) it is likely to make boost at lower rpm than in 2nd, I still don't think anything would be happening at 2500 though as the VSV hasn't opened the exhaust up to the turbos until much later.

[Tricky-Ricky]

Ok for Ian and the doubters:tongue: here is the link to the RR charts http://www.mkivsupra.net/vbb/showthread.php?t=92823

as you can see on the chart with only 300BHP there is is 0.8 bar at 3,500 RPM

attached are a couple of data charts, one is from the RR session, and as you can see there is 14 PSI at 3,180 RPM and on the other which is the RR there is nearly 11 PSI at 3,600 RPM but you have to take into account the loading, they are scanned as my laptop that i use for mapping is quite old:)

http://www.imagestation.com/picture/sraid222/p3e6b097d461c1f1ba680ce17c6a94bae/eb33701d.jpg

http://www.imagestation.com/picture/sraid222/pa07f366a3df71c372e949d871d35c480/eb33701e.jpg

 

The ECU can't learn as such, as the maps for fuel and timing are pre written, all the ECU can do is search within its maps using the also preset load maps to achieve the best fuelling/timing,

what it can do below 4,000RPM is as its running on closed loop it uses the lambda sensor to continuously keep the AFR values to 14.7 so it will use less fuel in TTC mode as its not seeing so much airflow into the engine as the first turbo is not operating, its only after 4,000 RPM that you can do anything about fuelling with something like e=manage etc as then the ECU will not continuously fight to bring the AFR back to 14.7

 

In TTC mode there is only one VSV left in operation and that is the waste gate VSV and this should have no bearing on things unless the ECU has a boost cut feature, other than fuel cut which is different, i have seen 1.4 bar before now:blink:

[Tricky-Ricky]

You wouldn't happen to have any data logs or anything of that, only it's a rather different story to what anyone else who's gone TTC says and either you've done something special that everyone would benefit from or your arse-dyno is lying to you

 

-Ian

 

As you asked, i included a couple of logs in my last post, as you can see my claim isn't bull, as for doing anything special, other than having the EGCV and the IACV wired open, no, did have the waste gate VSV eliminated before, but due to high boost in the cold weather, i switched it back, surprised you had no further comments.