****** TTG35forT - Rev 2.0 ******
Yeah, I still have the G...thats reminds me, time for me to start it up and let it run for a while
10-29-2011, 12:00 PM
#244
I just want it done, and done right, and Roger knows that. I have not been too much of a hard *** because I don't want anything to go wrong and I have been too busy with other things this year to keep on top of them.
10-31-2011, 03:15 AM
#253
Hi Chris. I've been busy, and coming on to the site just reminds me how much I miss my car. Once I have my car back, I'm sure I'll be pumped and get more active again.
10-31-2011, 09:23 AM
#255
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Location: Texas, Arizona,Cayman Island
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Expensive mistake.
Last edited by XKR; 10-31-2011 at 09:28 AM.
05-21-2014, 10:54 AM
#257
Here is a long overdue update on my car.
First, it took a long time for Roger to finish my car. A lot of weird issues popped up, for instance a dead F-CON. I finally got it back 6 or 7 months ago. There are still some issues to iron out, but we are almost there.
It turns out the .64 A/R on the turbine housings of my GT3071R turbos, and my Greddy exhaust system, are a little restrictive for the combination of the 4.0L motor and C8 cams. At 16 or 17 psi of boost I had 640 ft. lbs. of torque by 4200 rpm, but then it drops off. With the mid-pipe on the exhaust removed, this helped, and we were able to get over 600 whp (about 614 if I remember correctly) around 6k rpm or so (without fully optimizing the timing yet), but still, I want the torque to hold longer.
So, very soon, we will be changing the turbine housings. The .86 A/R version of the turbo has a different turbine, so that housing will not work. It looks like we will be having GT28 .86 A/R housings machined out to fit my turbines.
Also, another issue popped up. I had both the inside and outside of the turbine housings ceramic coated, but maybe I should not have done so on the insides. When the turbos heat up on the dyno after a few full boost runs, the boost ramp up all of a sudden gets delayed. We think the turbine blades in at least one of the turbos is scraping against the ceramic coating when the metal in the turbine housings expands. We won't know for sure until we drop the turbos and inspect them.
The weird thing with the exhaust is that it worked perfectly fine with my 3.5 L motor, C2 cams and Greddy 18G TT kit. It relatively easily made 609 whp. But the fluid dynamics are a lot different with the new setup. The Greddy exhaust is 2.77", but the resonators and mufflers appear to drop down to 2.5", which appears to be too restrictive with the new setup. I now have the parts to put together a custom 3" exhaust system, using 3" resonators and mufflers. The mufflers are Magnaflow, but I don't remember if the resonators are Magnaflow or a different brand.
Other than the turbo and exhaust issues we will be addressing, I'm pleased with the performance of the 4.0L motor. I'm going to need new tires, however. The rubber in my tires has hardened with it sitting so long. At 305 width, they break loose when the turbos spool up on hard acceleration, even in fourth gear... 640 ft. lbs. is fun to play with, though.
Once we get the turbine housing and exhaust issues addressed, we can go for more boost. The motor has 8.5:1 static compression. We measured 7.7:1 dynamic compression (dynamic compression is lower due to the 272 duration cams). With this relatively low compression, we should be able to give it a lot of boost, even on 93 octane. If I can hold 600 ft. lbs. to 7k rpm, we should get over 700 whp. We will see...
My H2O/meth system is not hooked up right now. Depending on how we do on pump gas, we can install that if need be to get further. First, I want to see how new tires handle the power after we make the turbine housing and exhaust changes. If we are at their limits, no use in pushing for more hp. Yes, I can put drag radials on the car, but that would not be optimum for road course use, which I plan on getting back to when we have everything complete.
First, it took a long time for Roger to finish my car. A lot of weird issues popped up, for instance a dead F-CON. I finally got it back 6 or 7 months ago. There are still some issues to iron out, but we are almost there.
It turns out the .64 A/R on the turbine housings of my GT3071R turbos, and my Greddy exhaust system, are a little restrictive for the combination of the 4.0L motor and C8 cams. At 16 or 17 psi of boost I had 640 ft. lbs. of torque by 4200 rpm, but then it drops off. With the mid-pipe on the exhaust removed, this helped, and we were able to get over 600 whp (about 614 if I remember correctly) around 6k rpm or so (without fully optimizing the timing yet), but still, I want the torque to hold longer.
So, very soon, we will be changing the turbine housings. The .86 A/R version of the turbo has a different turbine, so that housing will not work. It looks like we will be having GT28 .86 A/R housings machined out to fit my turbines.
Also, another issue popped up. I had both the inside and outside of the turbine housings ceramic coated, but maybe I should not have done so on the insides. When the turbos heat up on the dyno after a few full boost runs, the boost ramp up all of a sudden gets delayed. We think the turbine blades in at least one of the turbos is scraping against the ceramic coating when the metal in the turbine housings expands. We won't know for sure until we drop the turbos and inspect them.
The weird thing with the exhaust is that it worked perfectly fine with my 3.5 L motor, C2 cams and Greddy 18G TT kit. It relatively easily made 609 whp. But the fluid dynamics are a lot different with the new setup. The Greddy exhaust is 2.77", but the resonators and mufflers appear to drop down to 2.5", which appears to be too restrictive with the new setup. I now have the parts to put together a custom 3" exhaust system, using 3" resonators and mufflers. The mufflers are Magnaflow, but I don't remember if the resonators are Magnaflow or a different brand.
Other than the turbo and exhaust issues we will be addressing, I'm pleased with the performance of the 4.0L motor. I'm going to need new tires, however. The rubber in my tires has hardened with it sitting so long. At 305 width, they break loose when the turbos spool up on hard acceleration, even in fourth gear... 640 ft. lbs. is fun to play with, though.
Once we get the turbine housing and exhaust issues addressed, we can go for more boost. The motor has 8.5:1 static compression. We measured 7.7:1 dynamic compression (dynamic compression is lower due to the 272 duration cams). With this relatively low compression, we should be able to give it a lot of boost, even on 93 octane. If I can hold 600 ft. lbs. to 7k rpm, we should get over 700 whp. We will see...
My H2O/meth system is not hooked up right now. Depending on how we do on pump gas, we can install that if need be to get further. First, I want to see how new tires handle the power after we make the turbine housing and exhaust changes. If we are at their limits, no use in pushing for more hp. Yes, I can put drag radials on the car, but that would not be optimum for road course use, which I plan on getting back to when we have everything complete.
Last edited by ttg35fort; 05-21-2014 at 11:39 AM.
