Race day looking pretty UP for me. Need Opinion on something.

[Onefast99gsx]

Tonight after work I wanted to run my car out to the pretty much vacant Cty. Rd and do some more 0-60mph runs since i had a few more gallons of straight 116 oct. in the car. I made 4 good pulls and each one was better than the previous. I never thought the car would launch so hard that it would break loose and twist a bit sideways.

The 5th and final run I get out on a cross road a little better shape. Pretty heat soaked, intake temps at 100* and coolant at 210*. I wanted to do one last launch. Each time i was adding a bit more timing, more boost and a little less fuel. Probably still rich for race gas but safe. I was about 11.9:1 on dsmlink. Boost gauge showed around 20.5psi. Still low for what it should be but... i'm tuning. Don't want to go too far all at once.

So i lauch it and dam it launched hard. My amp and speaker gave loose and got slammed up against the tailgate area. Dsmlink shows a 0-60mph of 3.56 seconds. It was pretty dam good so i stayed in it and decided to 1/4 it. I ended up running a 12.72 et on gtech. Dsmlink shows a bit better than that but lets just say it's a 12.7.

Where i need the opinion:

My rev limiter is set at 8k rpms. 7bolt 2g motor. At the top of 3 gear a bit before the 1/4 mile, i started to bounce off the limiter for about .25 sec which hurt et a bit. Let just say this is a 12.0-12.5 right now as she sits, based on that..would you guys up the limiter to about 8300 and stay in 3rd gear or keep limiter where it's at and shift to 4th. I just don't know the rpms limits of the 2g. What's your experience on shifting? Stay 3rd or goto 4th.


DAM she felt good!!!

[Shane@DBPerformance]

Go into 4th, if your running faster than mid 13s you usually have to go into 4th gear. Do you have spring and retainers in the head to run high RPMs. I would be scared to make good HP and run higher than 8000RPMs on those tiny rods. RPMs in general are harder on rods than HP. What MPH did the DSMLink say? I would think you would have to go into 4th for a little bit, unless your not trapping that high or you have big tires.

[Onefast99gsx]

Thanks Shane. That's what i pretty much thought. I don't wanna risk blowing the motor for the sake of a few hundred r's. Stock springs and retainers. I want to keep the limiter at 8k and just shift at around 7800 then and go into 4th. Dsmlink shows just over 110-111mph where she's bouncing the limiter.

Question for you: 50trim, Magnus, 272's, FMIC, 1g tb, etc... 20.5 psi of boost, intake temps at 100*, Coolant at 210*, heat soaked everything, 89* outside temp. I was getting 39lbs/min. Is that low considering the variables or about right? I guess i'm just wondering at what point will i see about 45-47lbs/min?

Thanks for the great help.

[Onefast99gsx]

I may have found the answer to my own question on the dsmlink forums. Based on a fews peoples experience 39-40lbs is about right for that boost. Just as i thought intake temps play a big role too. I'm sure humidity plays a factor too. We all know how hot it was today.

Found this too: (averages)

T25 - 25LB@15PSI
14B - 29LB@21PSI
Small 16G - 30LB@20PSI 32LB@22PSI 33LB@24PSI
Big 28 - 33LB@17PSI / 34LB@20PSI
Big 16G - 35LB@24PSI (w/cams)
EVO 16G - 37LB@20PSI
GT30 - 38LB@18PSI
50 TRIM - 44LB@23PSI
TDO6H 20G - 40LB@20PSI / 47@25PSI (w/cams)

[Shane@DBPerformance]

You might want to ask Brian aka SlowWhite about the lbs/min. It sounds about right to me, but I am not an expert on what to expect for lb/min in the DSMLink software. Back when I had it, everyone wasn't obsessed with it like now and I had a hacked 2G MAS, so my values were not accurate. It would probably take around 27psi to see 45-47lb/min.

[Onefast99gsx]

Thanks Shane. I will touch base with Brian. I should add that i'm running 19" Racing Hart C5's. They're a bit on the heavy side. I'm trying to decide whether i should even bother testing the difference between two or just dump the C5's for race day and run stock 17" GSX wheels. I'm sure the 17" will help with the mph some not to mention the 60 foots.

[JET]

The main difference with lighter wheels is that you put a LOT less shock on the drivetrain at launch. That way you don't break as much stuff. There are some performance differences, but they aren't huge. The extra sidewall on the 17's will help your launch though.

[Onefast99gsx]

Thanks Jet. That sums it up. I never would have figured the first part and i'm glad you brought that up. I would have been under the assumption it was 100% performance rather than the important things like saving the tranny, axels, etc. I'll have to get the 17's back on it and see how they grip. When i got the car, they came with Vredestein(spelling?) tires. I never even heard of that make until i got the car.