Twin Turbo LFX Impressions

[GretchenGotGrowl]

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.

[lscamaro]

Congratulations!! This is truly remarkable. Its amazing what youve done with this car after everyone simply said it just couldnt be done! Hopefully all the little issues get ironed out to see that 10 second pass!

[soloknight6]

Wow...

[simt3k]

You can do bro! 10 sec V6 will surely shut those asshole V8 Drivers right the **** up.

Not that all V8 Camaro drivers are assholes, just the few

[GretchenGotGrowl]

Originally Posted by simt3k

You can do bro! 10 sec V6 will surely shut those asshole V8 Drivers right the **** up.

Not that all V8 Camaro drivers are assholes, just the few

The car guys don't give a #h1t, they like to see anything run fast. Most of the guys you see at the track think it's cool. Gives an opportunity to talk about what future V8s are going to look like. I can't wait until GM makes a 4.9-5.0 L V8 with all the tech they put into this engine. I know I'll want one!

[GretchenGotGrowl]

So a little background. We had just got finished with another round of changes and tuning the LLT right before CFest last year. We were making a good solid 445 RWHP despite the broken ring lands. First trip down the track and it fell on it's face about the 1000' mark. Never got it to go past that point under full power after that.

First pass down the strip this week and right at the 1000' mark the car upshifts to 4th and falls flat on its face. It immediately downshifted and the power came on like a rocket. So, I'm coming back on the return thinking "here we go again." We looked at the logs and just couldn't figure out what the F*** was going on. I did leave stabilitrac on because the track hadn't been used in over a month and they warned us to take it easy the first few passes. We decided to run it with all the nannys off and my happy face was on! Not sure what it is, but at least the solution is simple.

[Indy Bumble Bee]

Exciting news and can't wait for updates along the way

[V6owner]

Great write up! Glad you got it running great! Matt and Andrew are also trying to figure out the launching on these LFX's. it's crazy weird. I took Andrews down the track and when I foot brake it to launching it just bogs like crazy then it just takes off like a bat out of hell

Where is this video you speak of?

[GretchenGotGrowl]

Originally Posted by V6owner

Great write up! Glad you got it running great! Matt and Andrew are also trying to figure out the launching on these LFX's. it's crazy weird. I took Andrews down the track and when I foot brake it to launching it just bogs like crazy then it just takes off like a bat out of hell

Where is this video you speak of?

Kinda got lost on the other thread. Here it is.

http://youtu.be/or-E2aUrwEk

[Rhino79]

Car certainly exceeded my expectations for first outing. It was great that the only wrench we had to turn was the lug wrench! Shift point tweaking was the only thing needed on the tune!

I think the mileage issue has some to do with the lower compression but we can work on some fueling and timing at part throttle to help offset that.

[GretchenGotGrowl]

Originally Posted by Rhino79

Car certainly exceeded my expectations for first outing. It was great that the only wrench we had to turn was the lug wrench! Shift point tweaking was the only thing needed on the tune!

I think the mileage issue has some to do with the lower compression but we can work on some fueling and timing at part throttle to help offset that.

Yeah, the wide band worked perfectly from the time I got on the interstate until I stopped for gas in Conway. The whole time is was reading 13.4-13.8 so I'm pretty sure its fat on PT. Not too worried about it...how many 4000 lb 500 hp cars get 24 MPG at 75 MPH???

[KMPrenger]

Loving this write up!

Originally Posted by GretchenGotGrowl

So a little background. We had just got finished with another round of changes and tuning the LLT right before CFest last year. We were making a good solid 445 RWHP despite the broken ring lands. First trip down the track and it fell on it's face about the 1000' mark. Never got it to go past that point under full power after that.

First pass down the strip this week and right at the 1000' mark the car upshifts to 4th and falls flat on its face. It immediately downshifted and the power came on like a rocket. So, I'm coming back on the return thinking "here we go again." We looked at the logs and just couldn't figure out what the F*** was going on. I did leave stabilitrac on because the track hadn't been used in over a month and they warned us to take it easy the first few passes. We decided to run it with all the nannys off and my happy face was on! Not sure what it is, but at least the solution is simple.

I've heard others in the past say they would launch with TC on, then hit the button and turn it off once they've started moving on down the strip. Based on your findings this sounds like a good idea

[GretchenGotGrowl]

Originally Posted by KMPrenger

Loving this write up!



I've heard others in the past say they would launch with TC on, then hit the button and turn it off once they've started moving on down the strip. Based on your findings this sounds like a good idea

Had TC off but left Stabilitrac on. I'm not sure how mine would do with TC on at launch. Figure with the stall I wanted to get everything my tires could handle out of the launch.

[KMPrenger]

Originally Posted by GretchenGotGrowl

Had TC off but left Stabilitrac on. I'm not sure how mine would do with TC on at launch. Figure with the stall I wanted to get everything my tires could handle out of the launch.

I agree with your setup, or really with using slicks on any car that TC should be off, but with something closer to stock, TC on at launch seems to work fine.