I was ALWAYS under the impression that a twin screw was better for IAT's. Now I'm confused.

 

Supposedly twin screws are more efficient at making boost due to their internal compression design. Where as a roots rotor has more surface friction with the air charge as it packs the air charge into the manifold. (at least how I understand it) However, according to the combined gas law (PV/T=K), any form of compression in the manifold is going to produce heat. In my case, internal compression between the rotors is 15psi. My manifold pressure is only 11.7, therefore, in theory, the intake charge should be cooling off as the gas expands inside the manifold. None of this takes the intercooler circuit and manifold design into account though. I feel that Magnuson and even Whipple just do a better job of packaging the intercooler and cooling the air charge than KB. I can't tell you how many posts I have read regarding the IAT issues with the KB 98-04 Corvette kits (which is essentially what mine is with a longer drive shaft for truck accs). I am still not convinced that my IAT's are actually as high as what's being reported. Like Pat said, I should not be able to run 20+* on 93oct E10 without meth, but I have always been able to run that much timing without KR. I had it up to 24* on the previous setup when it was at 12psi.

 

An aftermarket heat exchanger made a tremendous difference on my vehicle. On the dyno running a 1.85 ratio on my 2.6L, I would see 170*+ iat on the dyno. Installed the GT 500 heat exchanger with fans with a 2.0 ratio, I would see 117* idling, cruising before and after pulls. On the street, I never was missing power again after the HE install. Now with a 2.5 ratio, IAT's are right around 137*.

 

How is the rebuild going? LS fest this year?

 

Truck is running great but I'm still tuning on it. I plan to hit the local 1/8 mile Saturday for some shakedowns if the weather cooperates. I was planning to do LS Fest again this year but have not heard anything from Truckin' about them doing Throwdown there again though. All my contacts from last year have moved on from the magazine. Still debating if I want to come and do the drag portion only, all around or just come watch and enjoy the weekend.

 

Well the track got rained out on Saturday so noting ground breaking to report with the truck. I was able to accomplish something I have been trying to do for a while. I added an extra air temp sensor in the inlet tube piped in thru the unused EGR port. Building the pull up circuit and physically adding the sensor was the easy part. What I had to think about was the custom pid in HPTuners considering the temp sensor curve is non-linear. Using an external input in HPT you can add the data index from the sensor to use as a lookup table. This data table function is not available with a custom pid using PCM parameters so I had to get creative. Thru a good bit of digging on the interweb and piecing things together, I found a way to plot the data in excel and have it spit out a polynomial equation I could intern use as a function for a custom pid. Basiclly you tabulate the data, plot it with a scatter chart, plot a trend line and have excel display the equation. Excel will take it out to a 6th order polynomial but HPT evidently has a character limit for the function so a 5th order was a accurate as I could get it. The higher the order, the more closely the trendline follows the data. A 3rd order gets it close but was about 7* high in the middle of the curve (about where ambient temp was Sunday when testing it). As you can see from the screen shot, it is pretty close to the other temps with the engine cold, KOEOff. My thermometer in the garage was showing 89* at the time of the screen shot, late in the afternoon.



I haven't driven the truck since installing the sensor but I am hoping this will provide some good data to see what my actual IAT increases thru the compressor are. I am expecting to see significantly higher than ambient inlet temps due to my intake/filter setup pulling in underhood air. However, if my inlet temps are close to ambient, it proves that there are some definite improvements to be made to the intercooler system.

 

Finally got to the track for some shakedown passes. There was a long rain delay but got three passes in. I was a bit disappointed in the truck. Best was 7.40@95 with a few issues. I have a boost leak causing fluctuating boost from 11 to 14 psi. The intercooler system is also being pressurized so I think I know where my boost leak may be. Just need to pull the blower and manifold and do a pressure test on the ic.

Started new thread with issue for opinions... https://www.performancetrucks.net/fo...harger-531374/

 

I took the trek up to Bowling Green, KY for the Holley LS Fest again this year. The truck had some bugs to work out which I worked on all day Friday and Saturday. Weather was pretty hot and humid both days. I think I heard some say the DA was 2600' Saturday. Things started coming together Saturday afternoon as it clicked off a 11.48@117.5. On the next pass to back that up, I broke a belt due to a loose tensioner pulley due to the bolt ripping the threads out of the tensioner arm. By time that was repaired the track was shut down for the evening. Therefor I did not fair to well in qualifying.
Sunday morning the air was a bit better and it was time for eliminations in the LSX Rumble index. My index was an 11.50 which I though I was going to be close to based on the end of the day Saturday. First round, I'm up against an LS swapped Eclipse that is dialing in a 10.50. I leave first and he passes me half track so I knew he was going to break out horribly so I stayed in it to see what the truck would run. Pass was great with a 1.707 60', 7.28@96.89 1/8mile, 11.31@120.77
http://youtu.be/YlHlfxCNTDE

Second round my opponent red lights so I say in it again to a 1.707 7.36@99.68 11.407@122.22
http://youtu.be/F31T2g8oRDo

Third round, truck leaves great and I am watching the other lane come up fast. I time it just right, let out just before the traps and barely cross the line first. Unfortunately, I broke out just a little worse than he did with a 1.67 7.31@97.84 11.34@120.91. That pass had the makings of a record pass in the 11.20 range.
http://youtu.be/QCe4UjTlNBk

The truck still has a few issues to iron out and the tune has some room to be tweaked a little so I think I am on track for the 10 second pass I have been wanting once we get some good air.

 

Damn, almost 100 mph in the 1/8th. That's haulin.

It looks like you're still running 20s up front??? Swapping to 15 or 17" skinnies alone may get you near 10s if that's the case.

 

They are 18x8 with 255/55/18 but I will be getting the 17x4.5/15x10 6-lug Racestars once they come available. Still debating what tires I want to run when I do get them though. I still have some suspension work to do too. I think a 1.5x 60' would get me real close to if not in the 10's.