brentil
10-28-2007, 10:18 PM
Seems like a lot of speculation going on here, the thing is though this engine has been out for over a year now in the Solstice GXP and Sky Redline.
I thought I'd share my wealth of knowledge on the subject to get you guys going on the right foot since we've made a lot of findings over the last year. Feel free to post questions and I'll answer them as I have time. I'me the admin for SolForum and SkyRoadster so you can be assured the info I'm stating is as solid as it's going to come. Being who I am I've made some contacts with GM and have gotten to talk about this engine a good bit with them.
This is a seriously complex engine with a lot of very complex control schemes that make it react in a way to certain mods you wouldn't have really expected it too. We've found a lot of simple mods that involve air intake have been kind of counter productive (unless you can get the car tuned which isn't 100% available yet). CAI, inter cooler piping, boost controllers are very notorious for causing Limp mode (engine disables boost completely and greatly alters timing). So far only exhausts and intercooler upgrades have proven to be truly effective with this Bosch controller keeping gains over time and not causing the dreaded CEL. Once full tuning is available it shouldn't be as much of an issue but the Bosch controller and the control schemes for this engine are very complex.
The LNF uses what is referred to as a Torque based management system. The engine uses a 3 dimensional graph of torque values and controls the turbo based on torque demands. So say for your altitude and temperature the engine only needs to create 16 psi to fulfill the current torque needs the engine will stop at 16 psi. Usually people in higher altitudes see higher psi since they need to compress more at higher altitudes to meet what a car at lower altitude needs. This control system has been found to cause certain mods as mentioned to also not produce as much power as expected because the control system ends up limiting the car.
The Borg-Warner K04 Turbo is a small turbo with a very quick spool. Some Audi and VW cars also use this turbo (however a different trim level) in some of their cars. GM likes to throw out the "260 ft-lbs available at 2000 RPM" however the number I prefer to state is 250 ft-lbs available 1500 RPM. We've seen the numbers and proven them ourselves on dynos that this engine is a powerhouse off the line. However being a small turbo we're already very near the compressor map limits at 20 psi. If you're wanting to build big power (400+) on this car you'll have to switch out turbos for sure. The LE5 2.4L engine has been proven from various vendors like Hahns that 350+ is possible on a stock LE5 which has parts that are definitely not as strong as the LNF which is superior to the LSJ engine in several ways. After market tunes have shown the K04 can reach 23 psi on a regular basis along with a higher redline to reach about 300HP on a stock engine with just a tune.
BSR offers the PPC tuner and Westers has a tune out for GXP/Redline already. HPTuners has a beta release but it can't fully control the engine yet. The tuning is still very immature and not full featured at this time. Once this main item is nailed down we will finally start seeing the true ability of the LNF engine and mods for it. The BSR's tune pushes the car to 23 psi peak and raises the redline to 7000 RPM for 1st and 2nd gear. Their tune has been dynod at 265 HP to the rear wheels on a Solstice GXP which comparing various dyno graphs the RWD GXP shows about a 14% drivetrain loss. 265 + 14% = 302 HP. There is currently some rumblings about possible Stage kits from GM but nothing official yet. A couple weeks ago however was the SCCA Club Racing Nationals which the Solstice took 1st in SSB and the Solstice GXP took 1-2-3-4 in T2. Talking to the people who raced the Solstice GXP in T2 GM was on hand with their sponsored teams and were helping the independents with engine tuning also. T2 allows for unlimited boost in turbo/supercharged cars, and according to the people racing GM removed all of the Torque limitations and ratched the boost up to 26 psi on the stock engine and turbo. A quote from one of the racers at the SCCA Nationals;
The torque management nanny has been completely removed, and we are boosting to 26lbs. There is no partial throttle response at all, therefore no driveability. Even a slight lift gets the car bucking and snorting as if it's just plain pissed off you lifted. Power and torque are strong, but utterly unsuitable for the street. If we have a wet race, the stock tune will probably be necessary. We are also having some issues with keeping turbo hoses intact. With the additional power the race car is making, the balance has shifted to power oversteer. I had a decent lap going in one of our qualifying sessions until I spun the rear tires in third gear coming off the final corner to the finish. It takes some impressive torque to spin a 275 Hoosier A6.
They've shown that the turbo is capable of 26 psi for race like environments with cars prepared for those types of events. Who knows what this does to the longevity of the turbo/car though seeing as how these races are only an hour long.
Things to be aware of with the LNF engine.
Turbo builds boost to demand levels, so depending on your region you may never see the full 20 psi. Seeing 14~17 psi on average is normal and within functioning values. You're still making 260 HP without having to hit the max 20 psi.
Yes the clicking is normal from the engine. The LNF uses a cam driven fuel pump with a high pressure solenoid to provide the 2000+ psi of fuel pressure the direct injection system requires under load. The clicking is the solenoid opening and closing and is a common feature of all DI engines (Mazda 2.3L, BMW 3.0L, Cady 3.6L).
Check your Turbo and intercooler tubes and check them often especially with modified cars. GM used a couple of T-clamps but for the most part they're cheaper screw clamps and are known to pop off.
I've got a 3" cat-back with no muffler/resonators on my LNF, all be it on a Solstice GXP. This engine freakin rocks. You can expect some nice gains from going to 3" tubing. The removal of the exhaust doesn't help as much as moving to 3" the engine is much more flow limited right at the turbo then it is at the outlet side.
YouTube video of the exhaust.
http://www.youtube.com/watch?v=qvqSgeEu2gg
Here's my before and after dyno comparison chart. I gained 16 HP peak and 5 ft-lbs peak at the rear wheels from the exhaust alone. However if you notice I gained about 25 HP and 25 ft-lbs after the peak.
http://www.inner-ninja.com/gallery2/d/13310-6/DynoRun.jpg
I thought I'd share my wealth of knowledge on the subject to get you guys going on the right foot since we've made a lot of findings over the last year. Feel free to post questions and I'll answer them as I have time. I'me the admin for SolForum and SkyRoadster so you can be assured the info I'm stating is as solid as it's going to come. Being who I am I've made some contacts with GM and have gotten to talk about this engine a good bit with them.
This is a seriously complex engine with a lot of very complex control schemes that make it react in a way to certain mods you wouldn't have really expected it too. We've found a lot of simple mods that involve air intake have been kind of counter productive (unless you can get the car tuned which isn't 100% available yet). CAI, inter cooler piping, boost controllers are very notorious for causing Limp mode (engine disables boost completely and greatly alters timing). So far only exhausts and intercooler upgrades have proven to be truly effective with this Bosch controller keeping gains over time and not causing the dreaded CEL. Once full tuning is available it shouldn't be as much of an issue but the Bosch controller and the control schemes for this engine are very complex.
The LNF uses what is referred to as a Torque based management system. The engine uses a 3 dimensional graph of torque values and controls the turbo based on torque demands. So say for your altitude and temperature the engine only needs to create 16 psi to fulfill the current torque needs the engine will stop at 16 psi. Usually people in higher altitudes see higher psi since they need to compress more at higher altitudes to meet what a car at lower altitude needs. This control system has been found to cause certain mods as mentioned to also not produce as much power as expected because the control system ends up limiting the car.
The Borg-Warner K04 Turbo is a small turbo with a very quick spool. Some Audi and VW cars also use this turbo (however a different trim level) in some of their cars. GM likes to throw out the "260 ft-lbs available at 2000 RPM" however the number I prefer to state is 250 ft-lbs available 1500 RPM. We've seen the numbers and proven them ourselves on dynos that this engine is a powerhouse off the line. However being a small turbo we're already very near the compressor map limits at 20 psi. If you're wanting to build big power (400+) on this car you'll have to switch out turbos for sure. The LE5 2.4L engine has been proven from various vendors like Hahns that 350+ is possible on a stock LE5 which has parts that are definitely not as strong as the LNF which is superior to the LSJ engine in several ways. After market tunes have shown the K04 can reach 23 psi on a regular basis along with a higher redline to reach about 300HP on a stock engine with just a tune.
BSR offers the PPC tuner and Westers has a tune out for GXP/Redline already. HPTuners has a beta release but it can't fully control the engine yet. The tuning is still very immature and not full featured at this time. Once this main item is nailed down we will finally start seeing the true ability of the LNF engine and mods for it. The BSR's tune pushes the car to 23 psi peak and raises the redline to 7000 RPM for 1st and 2nd gear. Their tune has been dynod at 265 HP to the rear wheels on a Solstice GXP which comparing various dyno graphs the RWD GXP shows about a 14% drivetrain loss. 265 + 14% = 302 HP. There is currently some rumblings about possible Stage kits from GM but nothing official yet. A couple weeks ago however was the SCCA Club Racing Nationals which the Solstice took 1st in SSB and the Solstice GXP took 1-2-3-4 in T2. Talking to the people who raced the Solstice GXP in T2 GM was on hand with their sponsored teams and were helping the independents with engine tuning also. T2 allows for unlimited boost in turbo/supercharged cars, and according to the people racing GM removed all of the Torque limitations and ratched the boost up to 26 psi on the stock engine and turbo. A quote from one of the racers at the SCCA Nationals;
The torque management nanny has been completely removed, and we are boosting to 26lbs. There is no partial throttle response at all, therefore no driveability. Even a slight lift gets the car bucking and snorting as if it's just plain pissed off you lifted. Power and torque are strong, but utterly unsuitable for the street. If we have a wet race, the stock tune will probably be necessary. We are also having some issues with keeping turbo hoses intact. With the additional power the race car is making, the balance has shifted to power oversteer. I had a decent lap going in one of our qualifying sessions until I spun the rear tires in third gear coming off the final corner to the finish. It takes some impressive torque to spin a 275 Hoosier A6.
They've shown that the turbo is capable of 26 psi for race like environments with cars prepared for those types of events. Who knows what this does to the longevity of the turbo/car though seeing as how these races are only an hour long.
Things to be aware of with the LNF engine.
Turbo builds boost to demand levels, so depending on your region you may never see the full 20 psi. Seeing 14~17 psi on average is normal and within functioning values. You're still making 260 HP without having to hit the max 20 psi.
Yes the clicking is normal from the engine. The LNF uses a cam driven fuel pump with a high pressure solenoid to provide the 2000+ psi of fuel pressure the direct injection system requires under load. The clicking is the solenoid opening and closing and is a common feature of all DI engines (Mazda 2.3L, BMW 3.0L, Cady 3.6L).
Check your Turbo and intercooler tubes and check them often especially with modified cars. GM used a couple of T-clamps but for the most part they're cheaper screw clamps and are known to pop off.
I've got a 3" cat-back with no muffler/resonators on my LNF, all be it on a Solstice GXP. This engine freakin rocks. You can expect some nice gains from going to 3" tubing. The removal of the exhaust doesn't help as much as moving to 3" the engine is much more flow limited right at the turbo then it is at the outlet side.
YouTube video of the exhaust.
http://www.youtube.com/watch?v=qvqSgeEu2gg
Here's my before and after dyno comparison chart. I gained 16 HP peak and 5 ft-lbs peak at the rear wheels from the exhaust alone. However if you notice I gained about 25 HP and 25 ft-lbs after the peak.
http://www.inner-ninja.com/gallery2/d/13310-6/DynoRun.jpg