20 replies to this topic

[zebwach]

Hello fellow vxers. This is more a question to people who have had the cms stage 5,or what ever you want to call it, carried out on their car. Ie a garrett 2871 plus the engine bits to allow it to breath and not blow up. What psi boost levels did you use to achieve the 370bhp ish levels? I ask as i my car is just about fixed again and i shall be going for mapping again in the near future. I plan on coming away with 3 or 4 maps to be used in different scenarios. 1/ average boost for every day use 2/ average boost with reduced initial torque for slippery conditions and for if my clutch or tyres are on their way out. 3/ max boost/power everywhere, for those pub bragging rights and cold, dry wintery conditions where temps aren't an issue. 4/ im not sure if its possible with the ecu, but maybe an option for a little extra fuel to be thrown in on the over run to make full use of my decat! Thats if the changes made to the poor quality parts supplied by cms have worked, if not then its back into storage while i save up for a different manifold and turbo. Fingers crossed. Cheers for you help.

[Goosenka]

Can you define " coming away with 3 or 4 maps to be used in different scenarios?"

[zebwach]

I have a standalone ecu that can change maps on the go. Its the Adaptronics unit supplied And fitted by chris from efi parts. Its amazing what it can do and has the added bonus of a cable operated throttle body.

[Goosenka]

Ah gotcha makes sense now

[Bumblebee]

I have a standalone ecu that can change maps on the go. Its the Adaptronics unit supplied And fitted by chris from efi parts. Its amazing what it can do and has the added bonus of a cable operated throttle body.

How are you finding the adaptronic,do you find the throttle. Bit on off?

[zebwach]

I didnt have long driving it before the headgasket went and it wasnt mapped past 5k rpm because cms supplied a downpipe that couldnt vent the boost that the engine was now being aloud to produce. But in answer to your question the power delivery is crazy smooth in comparison with the cms stage 4+ i was running before. Never any stutter and you get exactly the amount of power you request via your right foot. Ie, put your foot down half way and you get 50% power. Ill beable to give a full right up once it is mapped properly and i can post some graphs up to back it up. Anyone any ideas on boost levels or what the 2871 is capable of sustaining?

[Bumblebee]

Thanks for the info Are you using Chris for the mapping? I can highly recommend him as all my family have used him for a lot of years to Map there cars

[zebwach]

Yep, he mapped it before but couldnt complete it due to issues with hardware. He certainly knows his stuff. Im hoping he can fit me in at some point in the next couple of weeks.

[Nev]

Hi Zak,

From some research I did ages ago you can sensibly expect 370 BHP from a GT2871 with a Z20LEx, perhaps 380. I have overlaid several dyno plots below, the black line is a GT2871. Obviously every car will be different and the resulting power/torque depends on so many things, so you can only use it as a rough guide. Incidentally, the GT2871 plot was one given by Klassen a long time ago, still using the OEM ECU.



If you are using a Pro-Alloy CC, you might find the power is limited by the max boost the they recommend you run though it. On my car that's just 2.0 bar, you better check what your limit is otherwise over time the alu side walls of the CC may fail from metal fatigue due to constant changes of boost being applied.

HTH.

Edited by Nev, 04 August 2012 - 02:25 PM.

[zebwach]

That’s really good stuff Nev, thanks. I don’t suppose you know what boost levels were used to produce those figures do you?

It will be interesting to see how mine will fit in with those with the Dave/Duncan mega intake kit and the standalone ECU giving the engine that extra bit of freedom.

I blew up my charge cooler a long time ago! Iv currently got a super duper over the top carbo-tanium reinforced one!

2 bar is a lot of boost and certainly more than I envisaged it running. What kind of pressure is this turbo capable of and what pressure would you consider a reasonable amount to run before heat becomes a big issue?

[Nev]

That’s really good stuff Nev, thanks. I don’t suppose you know what boost levels were used to produce those figures do you?

It will be interesting to see how mine will fit in with those with the Dave/Duncan mega intake kit and the standalone ECU giving the engine that extra bit of freedom.

I blew up my charge cooler a long time ago! Iv currently got a super duper over the top carbo-tanium reinforced one!

2 bar is a lot of boost and certainly more than I envisaged it running. What kind of pressure is this turbo capable of and what pressure would you consider a reasonable amount to run before heat becomes a big issue?

Sorry, no idea about the boost levels used to create those maps

I suspect Duncans larger airbox/pipework will make quite a bit of difference, maybe a lot (like +25 BHP even) - such things become more and more influential as you go up in turbo sizes.

2 Bar isn't mega boost really, it's perfectly normal for a mid sized turbo. It's just that the OEM one is titchy so everyone gets used to that maxing out at around 1.4 Bar of steady boost. The GT2871 (depending on housing choice) is capable of a (usable/efficient) pressure ratio of around 2.6 bar, so providing your inlet pipework doesnt cause much of a resistance you can expect 1.6 Bar of steady boost, and a bit more on top of that if you really want to max it out.

I dunno what heat to expect, if you have the smaller hotside A/R snail you may get back pressure heat issue in the manifold and cylinder head due to the restriction of the snail. If you havent chosen the smallest A/R snail then you will likely be fine for heat, especially if you wrap it all with heat wrap.

Good luck with the CS hardware, hopefully their remedial work has finally worked.

[zebwach]

Strangely, the AR wasnt written on the housing. But from previous chats with CMS, the enphasis was always on minimal lag. It never crossed my mind at the time that this could cause further temp issues. Well it ran 345bhp just before the 5k rpm mark at 18-19psi last time. So im excited to see what happens when an extra 5 0r 6 psi is added on to that and its aloud to rev past 5k.

[Nev]

Strangely, the AR wasnt written on the housing. But from previous chats with CMS, the enphasis was always on minimal lag. It never crossed my mind at the time that this could cause further temp issues.

Well it ran 345bhp just before the 5k rpm mark at 18-19psi last time. So im excited to see what happens when an extra 5 0r 6 psi is added on to that and its aloud to rev past 5k.

From reading that, maybe your final map will get pretty close to (or creap over) 400 BHP then, cos making 345 BHP with just 1.2 Bar of boost leaves quite a bit of headroom for the turbo.

I can't remember, but do you have:

1: Oversize valves?
2: Strong valve springs?

Edited by Nev, 04 August 2012 - 04:08 PM.

[zebwach]

Nope, totaly standard head apart from uprated springs. I have swapped the head now though to a totaly standard low milage LEH one as my last head cracked. I think the exhaust manifold is meant to become a restriction at 400bhp, so cant imagine going past that. Im not sure at what point the uprated fuel pump runs out of puff either? Im waiting on delivery of some 630cc injectors to use along side my current 3.3bar pressure fuel reg. Will this be enough to fuel 400bhp? Any 2871 users out there that can shed some light on what boost levels they run?

[Nev]

630 cc injectors are ok upto around 500 BHP (running at 80% capactiy at that level). According to the pressure/flow values I got off Glencoe, the Sytec pump (if thats the one you have) should be ok upto about 425 BHP (+/- 25 BHP), so I think you will be fine on that front.

[zebwach]

Thats the one. Still a little close to the upper range of it. I cant afford to get any more power then, because I certainly dont want to eat in to my boot space with fuel pots and extra in line pumps! Just out of interest, what are the vxr (480cc) injectors rated to? Id rather keep them in if possible because of the better spray pattern.

[Nev]

I wouldn't worry about spray pattern TBH (it makes little difference in practice) and if you tried to keep your 480cc injectors you would almost certainly need to drive them > 80% duty cycle (even if you ran 5 bar of ppressure on the fuel rail). I am pretty sure Chris will confirm this when you go up there next.

[cnrandall]

I'm running 630 siemens on my and they are proper flat chat @ 420 @ the hubs and that's with race fuel with higher caloric value than road fuel. We found we maxed out the stock ones at 250 @ the hubs and the VXR ones @ 265 @ the hubs, all with the stock reg.

[Nev]

I think a lot depends on the BSFC of the mapper and the accuracy of the dynos (as I am sure we all know!). I know that Klassen manages to safely map to quite a low value (hence retaining relatively good fuel economy). When I got all the metrics/data from my dyno run and calculated the duty cycle from it, amazingly this was spot on 80% for the 630cc injectors at a certain point in the rev range (I forget where). I made a point of checking this, as I also was concerned about duty cycles (having originally bought 875cc injectors for the engine). However, I believe Zak is having his mapped by someone else and importantly won't have a MAF (ie the pedal mapped directly to boost demand) so I suspect the map will need to be richer as a result.

Edited by Nev, 05 August 2012 - 11:49 AM.

[zebwach]

Nev. This is true, i no longer require a MAF. But why does this mean i need to run it richer than i other wise would?