993GT2 gets bling boost controller for +50bhp gain
Discussion
As we push the boundaries of boostmeistering turbopork further into the unknown IMOM's GT2 came under the spanner this week to have its wayward boost performance sorted for good.
To cover a little of the history of this ongoing project, VC, JC & DeR have had their 993TT engines fettled with turbos, injectors and remaps and have all suffered (to some degree) with the anomalies of the motronic boost control system, ie hitting the overboost limit occasionally.
What happens is as a result of a slow response speed allowing "flash" overboost at peak torque to spike the boost/MAF limit, thus bringing in the onboard boost limiter. Whilst essentially annoying on the road, on the track it could be dangerous if it came in mid bend, so the problem had to be resolved.
With DeR's turbo we managed to fool the system by carefully sizing some of the control pipework, but for some reason we could not get this to work on IMOM's GT2, probably due to the larger K24 turbos. In any case following our previously unsuccessful & exhaustive (all night 5am) attempts to get the Motronic system to do the job properly it was time to have a rethink and come up with a permanent guaranteed solution.
We resorted to fitting the most sophisticated aftermarket boost controller we could find along with a pair of new billet recirculation valves to prevent premature boost leakage back into the intake. Once hooked up correctly the new controller looks at vehicle speed and throttle position whilst the engine is under load and through clever electronics it learns the boost response through the gears and actually anticipates the rate of change, so trimming the control valve's duty cycle to ensure the preset boost level is maintained at all times. Clever stuff indeed, the results speak for themselves.
The boost controller has two settings. For the high boost mode we dialed in 1.0bar. Under load on the dyno it maintained this perfectly with a peak boost flash of just 1.03bar to finally give 775Nm & 544bhp. After several further runs this huge torque peak at 4500 gave a couple of hiccups (overboost), so by dialling in less duty at this rpm we maintained the power level and trimmed the torque to 755Nm for perfect repeatable runs under load. This compares favourably with the previous best of 490bhp/700Nm under Motronic control.
For the low boost setting we dialed in 0.9 bar which pulled the power back to 520bhp & the torque to 720Nm, figuring that IMOM could adopt this map should the Motronic decide to hiccup on track for some reason.
Once the high setting has been proven we intend to dial in the low option for a mild torque but high top end, circa 500bhp which would be ideal for the wet. Hopefully IMOM will give us all some feedback after testing in a week or so's time.
To cover a little of the history of this ongoing project, VC, JC & DeR have had their 993TT engines fettled with turbos, injectors and remaps and have all suffered (to some degree) with the anomalies of the motronic boost control system, ie hitting the overboost limit occasionally.
What happens is as a result of a slow response speed allowing "flash" overboost at peak torque to spike the boost/MAF limit, thus bringing in the onboard boost limiter. Whilst essentially annoying on the road, on the track it could be dangerous if it came in mid bend, so the problem had to be resolved.
With DeR's turbo we managed to fool the system by carefully sizing some of the control pipework, but for some reason we could not get this to work on IMOM's GT2, probably due to the larger K24 turbos. In any case following our previously unsuccessful & exhaustive (all night 5am) attempts to get the Motronic system to do the job properly it was time to have a rethink and come up with a permanent guaranteed solution.
We resorted to fitting the most sophisticated aftermarket boost controller we could find along with a pair of new billet recirculation valves to prevent premature boost leakage back into the intake. Once hooked up correctly the new controller looks at vehicle speed and throttle position whilst the engine is under load and through clever electronics it learns the boost response through the gears and actually anticipates the rate of change, so trimming the control valve's duty cycle to ensure the preset boost level is maintained at all times. Clever stuff indeed, the results speak for themselves.
The boost controller has two settings. For the high boost mode we dialed in 1.0bar. Under load on the dyno it maintained this perfectly with a peak boost flash of just 1.03bar to finally give 775Nm & 544bhp. After several further runs this huge torque peak at 4500 gave a couple of hiccups (overboost), so by dialling in less duty at this rpm we maintained the power level and trimmed the torque to 755Nm for perfect repeatable runs under load. This compares favourably with the previous best of 490bhp/700Nm under Motronic control.
For the low boost setting we dialed in 0.9 bar which pulled the power back to 520bhp & the torque to 720Nm, figuring that IMOM could adopt this map should the Motronic decide to hiccup on track for some reason.
Once the high setting has been proven we intend to dial in the low option for a mild torque but high top end, circa 500bhp which would be ideal for the wet. Hopefully IMOM will give us all some feedback after testing in a week or so's time.
Sh1t - I need to ring 'Cool Hand' Wayne to come round and fix my 'spike' on the morrow...
I look forward to headbutting illicit numbers, unhindered by respiratory hiccups!
Schnell, schnell!
Is all this 'blown' technology cooking yon swede, Ninester?
Edited to say: "Bleedin' gorgeous GT2, btw!"
>> Edited by derestrictor on Wednesday 11th May 19:50
I look forward to headbutting illicit numbers, unhindered by respiratory hiccups!
Schnell, schnell! Is all this 'blown' technology cooking yon swede, Ninester?
Edited to say: "Bleedin' gorgeous GT2, btw!"
>> Edited by derestrictor on Wednesday 11th May 19:50
Yes, the same system will fit onto the 996TT and should give similar results. The value of fitting the kit depends on the control quality of the 996 DME w.r.t. boost with the proviso that the DME has been mapped correctly to cope with said boost level.
In the case of all of the above mentioned cars, they are all running a fine tuned version of the same map with large injectors, so we know that the fuelling & ignition are sorted before we twiddle the boost. I suspect that 550 bhp will be the upper limit of the stock MAF/rpm algorithm, so from here on it will get more involved, but up to this level the controller is the way to go.
Ah yes JC, I was forgetting myself for a moment, IMOM's feedback will probably be limited to single sylable expletives from the general direction of the nearest bar once you two get together again .....
In the case of all of the above mentioned cars, they are all running a fine tuned version of the same map with large injectors, so we know that the fuelling & ignition are sorted before we twiddle the boost. I suspect that 550 bhp will be the upper limit of the stock MAF/rpm algorithm, so from here on it will get more involved, but up to this level the controller is the way to go.
Ah yes JC, I was forgetting myself for a moment, IMOM's feedback will probably be limited to single sylable expletives from the general direction of the nearest bar once you two get together again .....
blingmeister, some caution on "A" and "B" setting on Apexi AVCR from Harvey Smith and Andy Forrest
"As I have found, you are wasting your time trying to get the self learn to work until you input all the correct info and in particular to the etc section. Once that in and correct the self learn works well.
Previously came across a case where "Settings A" would overshoot and generally not control boost to a fine degree. The info was put in "Settings B" and it worked precisely. "A" was still wandering about unacceptably but "B" was OK."
and
"Just finished the AVC-R on my WRX. Settings A holds 1.5 bar perfectly but Settings B will not hold 1.2 bar reliably and vice versa. Weird. It was Andy F. that discovered the differences in the A and B settings on the STi in the first place.
Try both settings."
http://bbs.22b.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=7;t=000435#000018
"As I have found, you are wasting your time trying to get the self learn to work until you input all the correct info and in particular to the etc section. Once that in and correct the self learn works well.
Previously came across a case where "Settings A" would overshoot and generally not control boost to a fine degree. The info was put in "Settings B" and it worked precisely. "A" was still wandering about unacceptably but "B" was OK."
and
"Just finished the AVC-R on my WRX. Settings A holds 1.5 bar perfectly but Settings B will not hold 1.2 bar reliably and vice versa. Weird. It was Andy F. that discovered the differences in the A and B settings on the STi in the first place.
Try both settings."
http://bbs.22b.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=7;t=000435#000018
verysideways said:
Colin - would these boost controllers be any good on a standard 993TT? I love the lag free performance of the K16's but i'm sure the thing can run more than 0.8 bar without batting an eyelid right?
VS
DeR's K16's (albeit with modifications) have pushed 595bhp on the dyno so don't be too quick to pan the stock turbos. I do know that with a stock ecu or stock injectors the Motronic boost controller can cope well enough but to answer your question: yes, the system would work on a standard car but it is a guess as to how much boost that it could safely run without other mods.
The real benefit of this system comes in when you are pushing 1.0 bar and posting over 500bhp following a remap and larger injectors, at which point the stock boost control system is nigh on impossible to get working correctly. My guess is that JC, DeR & VC will form an orderly queue once IMOM has sampled the goods.
Only in the sense of accurate reporting[slightly sarky Colin!] I have never yet suffered the dreaded problem JC and RG have , though over a curry last Monday Russell almost convinced me i had, Lat month,Mine had the almost statutory dump valve split diaphragm , so changed both also waste gate actuators and actually had two rotten Lamba sensors overiding things
ninemeister said:
...there will be no need to fit K26's unless you are aiming above 800bhp and you want to do it the hard way.
[Hugo Drax mode ON] Herr Belton, you theorise with the...tedious inevitability of an unloved season. [Hugo Drax mode OFF]
Can you imagine 800bhp? Can it be done whilst retaining some semblance of useable, road-bourne legality?
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