Twin Turbo 928 fixed and back out there terrorizing the streets!
#556
that is insane power.... I'd imagine you could get more if you went to a stand alone ecu like some of the newer motec's.
#557
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The 703 was the last run of the day and everything was heat soaked. The next morning, wihout any changes, it put down 711_rwhp@ 688 lb/ft.
This has really kicked me in the @$$ and motivated me to get crancking on my turbo project again. Thanks for the motivation Tuomo!!
This has really kicked me in the @$$ and motivated me to get crancking on my turbo project again. Thanks for the motivation Tuomo!!
The eboost2 profiles were changed between the runs. The 711 axle hp run has a lower boost at 4000-5000 rpm range and slightly higher boost set point above 6000 rpm, although the back pressure was forcing the wastegate open in the upper end so not much could be done there. The 711 axle hp run consequently had a lower peak torque at 662 ft-lb (and less knock events).
#558
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My car is not strip or track ready yet, for three reasons. First, there are some traction control issues on first and second gears with my current tires. I need the boost profile selection to run automatically off the shifter and fit wider and stickier tires. Second, especially with wider and stickier tires, the g-forces are such that the stock oil control may prove an issue for the stock engine. Something needs to be done there. Third, for longer test stints, I need to have the transmission oil cooled. The engine cooling will also possibly become an issue for longer runs.
There are three check valves. One near the front of the car and one each at the pump outlets.
Right now, I don't think we'd make much more power with a more recent ECUs. Where do you think a modern ECU could make more power with the current engine?
#559
Nordschleife Master
more efficient ignition system capable of a much stronger spark can help.
Why 3 check valves? I only see the need for 2.
With stickier tires, you do run the risk of breaking things....
Why 3 check valves? I only see the need for 2.
With stickier tires, you do run the risk of breaking things....
#560
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#561
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In terms of the ignition system, since we're running 93 octane pump gas (not racing gas or ethanol) in a 9.4:1 compression turbo motor, we aren't experiencing noticeable misfires nor are we expecting any. Where's the benefit from a higher voltage ignition system?
In terms of the fueling, I am guessing that we have very good fuel atomization. The charge is hot, dense, and turbulent. Sequential injection is not going to give us significant cooling or atomization benefits. Also timing the pulse from injectors to fill the cylinde better is an insignificant drop in the bucket when you have a turbocharger force feeding the cylinder.
If there's something to be changed about the stock computers, it's that we would could use:
(1) more resolution at higher rpms
(2) the ignition and fuel grids to coincide
(3) individual cylinder fuel and ignition trim maps
(4) boost control integrated with ignition control and knock sensors
(5) traction control integrated to the ignition control and boost control
Those would help by making tuning easier and car faster on track. I don't think they'd help that much with the peak power dyno number. I might be wrong, though.
The third check valve is a legacy from when the car was running a single Fuelab pump.
I agree that changes may have to be made to counterbalance the increased risks from stickier tires.
#562
The tuning benefits that come from after market ecu units cannot be brushed aside. Knock control at the limit, fueling precision, etc create large differences.
#563
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Also timing the pulse from injectors to fill the cylinde better is an insignificant drop in the bucket when you have a turbocharger force feeding the cylinder.
Somewhere, deep in the bowels of Forum History is a thread in which there appears a picture of a 928 with 8 wide-band oxygen sensors and some accompanying discussion of the A/F variance across the cylinders. (That's all I remember: 8 O2 sensors, A/F variance. I don't remember who posted it, who's 928 it was (Simard?) and if it was NA or FI (and what flavor FI if FI.))
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Oh, BTW: 700+ rwhp!
#565
Todd
#566
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If there's something to be changed about the stock computers, it's that we would could use:
(1) more resolution at higher rpms
(2) the ignition and fuel grids to coincide
(3) individual cylinder fuel and ignition trim maps
(4) boost control integrated with ignition control and knock sensors
(5) traction control integrated to the ignition control and boost control
Those would help by making tuning easier and car faster on track. I don't think they'd help that much with the peak power dyno number. I might be wrong, though.
The third check valve is a legacy from when the car was running a single Fuelab pump.
I agree that changes may have to be made to counterbalance the increased risks from stickier tires.
1-5 are possible with a Motec or other ECU..... The peak may not change, but the curve may get more area.. Just my $0.02
#567
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But, will it give you better control of the air-fuel ratio? ... through the stock intake manifold in your case. Somewhere, deep in the bowels of Forum History is a thread in which there appears a picture of a 928 with 8 wide-band oxygen sensors and some accompanying discussion of the A/F variance across the cylinders. (That's all I remember: 8 O2 sensors, A/F variance. I don't remember who posted it, who's 928 it was (Simard?) and if it was NA or FI (and what flavor FI if FI.))
Contrary to other people's experiences, we don't get some cylinders knocking much earlier than others as we lean the fuel and advance the spark, so this is not the most pressing problem right now. We're in a minority with that opinion and experience. We're also in a minority thinking that the stock intake manifold is not the most pressing bottleneck in the turbo engine as currently in the car. All the current bottlenecks for more power are control problems, and after those control problems are solved two larger turbochargers are needed before we see any need to change the intake manifold. Eventually, it will have to go, too -- just not yet.
It was Todd Tremel who run the 8-sensor WBO2 test with an Autronic ECU and Hacker who posted about it. That was very useful information for them to share with the community. It's not a coincidence that Todd Tremel holds the current 93 octane pump gas, stock long block peak power record at 722 rwhp.
We don't have a practical way to run an 8-sensor WBO2 system on this car. It is very hot and very crowded in there around those exhaust manifolds, and the exhaust test ports in the head are very hot and very inaccessible. A more practical alternative for this engine would be to run the TFX cylinder pressure sensor system with pressure sensors in the spark plugs, which would allow for a lot more data collection than inferring the optimum fueling. The downside of this system at this point is that the cheapest model starts at $7k, install and debugging is time consuming, and our the stock ECUs don't have an individual cylinder trim so I am not sure we could do much with the info right away.
It's a good result, but nobody's popping champagne bottles here yet...
Here's my view: If one wants to blow many thousands of dollars on this engine, I believe that right now at this level there are much more cost effective ways to do that than to go to an aftermarket ECU, all new wiring, etc.
#568
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We're in a minority with that opinion and experience. We're also in a minority thinking that the stock intake manifold is not the most pressing bottleneck in the turbo engine as currently in the car. All the current bottlenecks for more power are control problems, and after those control problems are solved two larger turbochargers are needed before we see any need to change the intake manifold. Eventually, it will have to go, too -- just not yet.
I will gladly send bubbly when you get to 800
#569
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The cost of some standalone systems is very high, I do concur.
But some systems really are not that expensive.
VEMS for instance has tons of features, lends to MUCH better fueling control over stock system, switching to COP lower RFI, as well as the ability to run much larger gaps (think .045" up to 30 PSI ).
One of the key benefits as well imo is switching to MAP and being able to ditch the MAF. This gets you much more consistent fueling, no worry about turbulence in the air stream, among other benefits.
This system has dual knock control, built in EGT (with targeting), can have knock control, boost control, meth injection control, built in WB controller, and 3d map tabling with the ability to change the RPM columns to be able to get more resolution where you need it.
the cost for the brain, connectors (WB, knock, hall, injectors) is 730 euro or $955 usd. You will need to get an ign system setup on top of that, so say around $300. But all told, this is pretty cheap if you complete the install yourself. If you pay someone to install and setup for you, then it gets more expensive pretty quickly. But this system is more than capable.
But some systems really are not that expensive.
VEMS for instance has tons of features, lends to MUCH better fueling control over stock system, switching to COP lower RFI, as well as the ability to run much larger gaps (think .045" up to 30 PSI ).
One of the key benefits as well imo is switching to MAP and being able to ditch the MAF. This gets you much more consistent fueling, no worry about turbulence in the air stream, among other benefits.
This system has dual knock control, built in EGT (with targeting), can have knock control, boost control, meth injection control, built in WB controller, and 3d map tabling with the ability to change the RPM columns to be able to get more resolution where you need it.
the cost for the brain, connectors (WB, knock, hall, injectors) is 730 euro or $955 usd. You will need to get an ign system setup on top of that, so say around $300. But all told, this is pretty cheap if you complete the install yourself. If you pay someone to install and setup for you, then it gets more expensive pretty quickly. But this system is more than capable.
#570
Don't quote me, but IIRC, you the newest mega squirt MS3x should be able to handle all of those goals, without the need for an external ignition system. Also has fuel and ignition switching capability which could then produce essentially double the fuel and ignition map resolution.