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MISCELLANEOUS MODIFICATIONS
NOTE! NO NEW MODS EXCEPT DRESS UP ITEMS SINCE 2001
It's been a while since updating this page so I will try to update everything I did to the GN since 2000. My only outing to the track in 2000 resulted in my times actually getting worse instead of better. The biggest problem was having a problem building any boost on the line. With the gas pedal matted and the transbrake engaged I was only seeing a measly 3-4 lbs of boost. Spent most of that summer trying to get my lost performance back. I am by no means a tuning wizard but tried just about any advice people in the know gave me to no avail. The summer quickly came to end and I spent the fall and winter of 2000-2001 doing some other upgrades.
TRANSMISSION
First up was a new higher stall torque converter, bought an orange stripe 2800 rpm stall from Jack Cotton. I decided to also put in a hardened stator while I had the transmission out. Thanks to Jack Cotton for putting the stator into the trans for me! I put the transmission back in and some of the performance I was missing was now back. The higher stall helped quite a bit but it still wasn't quite where I wanted it yet.
ALCOHOL INJECTION
After reading a lot of posts about alcohol injection, I decided to try my hand at this modification. Found a great DIY kit by Steve Monroe and followed his guidelines for installing it. Go to my alcohol page to see more details on this. The results were well worth it!
INTERCOOLER
I also was torn between going with a new CAS stretch intercooler or modifying the stock one with a Duttweiller inlet neck. Decided the $$$ were not there for the new intercooler at this point so I went with the Duttweiller neck. Pretty easy modification and guess what? After I did this mod, just for the hell of it I did a transbrake on, gas to the floor deal in my driveway and lo and behold the boost shot up to 8 lbs and was climbing when I let off! Did just the neck mod fix things? Not sure but don't care, the problem was gone! Steve Monroe's website had a great page on how to do this yourself. I followed his instructions for cutting off the stock neck and had my welder put on the new neck. Took it home and carefully grinded the weld down, a bit of body filler, some sanding and a coat of paint and the intercooler looked like new without any hint of what was done to it.
ALUMINUM BUMPER BRACES
Next was changing out the heavy steel bumper braces with a pair of aluminum braces. Pretty easy way to take off about 37 lbs of weight and beats going on a diet myself! Took a couple of pictures to show each reinforcement brace on a scale and you can see a 17 lb weight savings for the front bumper. If you look at the full size pics you will see that the steel brace weighs a little over 27 lbs and the aluminum brace is just a tad over 10 lbs. I did this by myself but would really recommend an assistant as the bumpers with the steel braces weight a ton! The rear bumper brace is the heavier of the two and you save about 20 lbs by switching to the aluminum one. These can still be found in the junkyards and can be seen on ebay once in a while.
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POLYURETHANE DRIVERS SIDE MOTOR MOUNT
I decided to try out one of those new polyurethane motor mounts that recently came out from HRpartsNstuff. I only purchased the drivers side mount as this is the one that sees the most abuse. It cost $79. Installation was very easy except I drilled the holes for the block mounting part of the mount one size bigger so it was easier to get the bolts to thread in. They say for cars slower than 12.00 you no longer need the tie down strap but I'm not sure if I am going to take mine off or not. Not a cheap part but the quality of the workmanship is worth it. Took about an hour to do with the front bolt on the block the hardest to get to but it wasn't too hard. One bonus, I did notice that my power steering hoses were rubbing on the frame so I moved them enough to get some clearance.
Click
on the photos to see full size!
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CLEAR SIGNAL LIGHT LENSES
Got this idea off the www.turbobuick.com message board. Easy 2 minute modification gives your GN a whole new clean look. These clear lenses are off an 83 Regal and are still available from GM, about $35 each since they replace the whole signal light assembly.
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FORD 9" REAR
A Currie Ford 9" rearend was in the GN when I bought it back in 1995 and I finally burned up the posi unit at the last track outing I attended in 2000 so that was rebuilt. In addition I switched from the 3.70 gears that were in it when the car was purchased to a closer to stock gearing of 3.50. Thanks to Tony Scinto for the rebuild! Painted the housing up real nice with Russell chassis epoxy and reinstalled.
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Transmission time! I had previously installed a Level 10 shift kit which I was happy with but my last track experience convinced me to try one of those Stage Right trans brakes. I guess I just lack the coordination for making a good launch with these cars and my emergency brake launch technique was always good for a laugh. Can't wait to try out the trans brake this season. A transbrake will hold the transmission in 2 gears at once which essentially locks up the transmission so you can build boost without the hassle of trying to hold the car on the line with your brakes. Some people can do it that way but I never felt it was very consistent. UPDATE-I can now launch at 10lbs of boost with the trans brake. GN is now running 12.20's!
I had seen some posts on the GN-T-type mailing list about converting to a 4L60 bottom feed trans filter and decided to do this as well since the pan was already off for the transbrake installation. This was a pretty easy modification with the hardest part being the grinding down of the stock filter standoffs in the deep pan that I already had. The deep pan is mandatory for this filter switch and will NOT work with the stock pan. The theory here is that a bottom feed filter will not suck air when the car is launched while racing. The stock filter is a top feed, meaning the hole for the trans fluid is on the top of the filter. It can possibly be uncovered during a hard launch! Click here to go to the DRW transmission website to learn how this is done! I used GM filter#8657926.
