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Old 02-02-2013, 11:54 AM   #1
GretchenGotGrowl


 
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Drives: 11 F150 EB/13 Sonic RS/15 Z06
Join Date: Sep 2010
Location: Little Rock, AR
Posts: 7,129
Twin Turbo LFX Impressions

I've had the car for a week now and though I would start a thread to log my impressions as we tie up all the loose ends.

First of all, we got all the plumbing the way we wanted it this time. These EFR turbos are amazing. They have an internal bypass that recirculates the blow off. We left the old BOV on, but I've yet to hear. The turbos handle it very well at 14 psi when doing monster burn outs so I don't see it ever being an issue. The nicest thing about the recirc is I don't lose any boost when shifting. At the track it would spike (more on that later) right when it got past the 40-50% TP (more on that later) and then keep it between 13.5-14.0 psi all the way down the track.

As for the spike, well we think it is because of the selonoid. The EFRs are supposed to come with built in ones, but mine didn't for some reason. We think our selonoid is just too far away from the turbos. These things spool so fast that we just can't get a signal to them to open the built in waste gates fast enough. Now, the spike is not as bad at the track where I get some traction as it was on the dyno and the street. However, we are so close to the edge on fuel right now we are going to keep the boost down until we can get it fixed.

The throttle issues is a weird one any may be the hardest one to fix. When we launch we are commanding 100% throttle but it will only give us about 40-50%. We must be missing some tables because everything we can see suggests that shouldn't happen. If you look at the time slip I posted you'll see it in the 60'. I could pull a 1.7x with the old car using my street tires. We couldn't pull better than a 1.8x with slicks with this car. Once it gets past that point the car takes off like a rocket and pulls hard all the way down the track. We added 5% to the duty cycle on the boost and it just pulled just the same, only harder. The power band is so wide and the recirc so good that you hardly feel the shifts. It's what I imagine an all electric race car must feel like.

Now for overall impressions. One word ...WOW! This feels like a car that came from the factory with turbos. You can't hear them from outside the car (well, except when you let off from WOT), and barely hear them inside. It has power at the touch of the accelerator once you are already moving. When we get the throttle issue fixed then it will be that way from a dead stop. The 3200 stall feels fine for street driving but may be a bit tight for the strip. Finally, we haven't worked on the street tune much so we are only getting about 24-25 MPG on the highway at 75 MPH. We know it is fat so we'll be working on that in the next few weeks.

While doing this I decided to go ahead and get all the BMR bushings (front, too). The thing simply rides on rails now.

At the strip, what can I say. Watch the video Nitroman28 took. We are losing at least .3 sec just because of the throttle problem. This is on a full weight car running less boost than we did for our 500 RWHP dyno pulls. I think I've got a good shot at breaking into the 10s.

We've got a few things to do. Obviously the throttle issue and a good street tune. We have also got to move the wide band further back. We aren't sure if it is the higher boost or lack of exhaust manifolds, but they are just getting too hot in the recomended location. We are going to put a heat sink in just to be safe. Aaron is working on an auxillary fuel system I'll let you know more about later. This will get us some extra fuel to the intake manifold as well as have a nitrous fogger system built in for the giggle juice guys. The prototype will probably be fabbed up in another week or two, but testing and tuning will probably take a while so just be patient. If all the calcuations are right, it should support a 175 shot and give us boosted guys enough fuel to go safely up to about 600 RWHP. All theory at this point.

Finally, gotta say the guys at GPI (Aaron, Ryan, James) and Saheen Racing did a great job. The car really feels like it came from the factory like this.
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