All,

Need help understanding why my trucks performance mods are not giving it the performance enhancements that I’m after.

SETUP: 1996 Auto with DTT 93% torque converter, livestock valve body and master overhaul kit, TST #8 plate (230 hp, 605 torque) in factory position, AFC slide full forward. No Cat, has flow through style muffler, and 4” pipe all the way back. I ran the truck for years with this setup and it worked great. Pulling my 5th wheel on steep interstate hills the boost would hit 32 lbs and the cruise would always hold 74 mph (2000 rpm). The truck would always have enough power to hold the speed. When pulling my 4WD on a 16’ trailer I learned how to pass going uphill!

Well like others I thought I could improve further on a good thing: I had the timing adjusted to 15.75 deg (CPL 2174, 4.85 mm plunger lift), and a 3000 RPM Governor Spring Kit installed. I have checked the timing myself to verify that it was in fact set correctly.

Here is what its doing ever since the timing was bumped and GSK addition: The max boost used to come in early like 32 lbs by 2000 rpm. Now the only way the truck pulls 30-32 lbs boost is with the overdrive locked out and letting the rpm’s get to about 2600. It now only pulls 20-24 lbs in drive at 2000 rpm’s. What this means is now the truck does not have enough power to pull steep interstate hills with the cruse control set. It gets behind going up the hill then over shoots when passing the top. The engine will now freely rev to redline…so the GSK seems to be working. I just don’t like the fact that the max boost has been slide so far to the right and is no longer accessible in drive while on the interstate. I have really thought about removing the GSK. Can the GSK be adjusted to allow more boost at lower RPM while still allowing the engine to rev to around 2800 rpm when overdrive is locked out? I’ve checked the fuel pressure and it is 24 psi at idle, 33 psi at 2500 rpm, and 30 psi with foot on floor during speed run. I’ve also tried moving the TST #8 plate all the way forward. This did not help with moving max boost to lower RPM only created a problem where the engine would “buck” when I put the pedal down while towing. I moved the #8 plate back to the factory position.

Would appreciate advice from any of you that have been there done that and found a good solution!

Thanks,

Don Ferguson

 

Have u checked where ur gov arm hits the plate? the 'buck' sounds like the gov arm went under the plate when u had it forward and then jumps back on the plate and thats why u had the bucking.

I have a 3gsk, and I can hit 34psi pretty much anytime if I put the pedal down, but thats with no load. With a load it doesn't really depend where my rpms are, it depends how deep my foot gets in the pedal. So that makes me think it's not the gsk, but more ur gov arm, plate posistion, or mabye the boost line got loose, or the timing changed it.

 

After I put my 3K GSK in I also had trouble hitting the high boost numbers in overdrive, I solved that problem by going to a custom ground plate (similar to a zero) now 40 psi in any gear is no problem.

 

Thanks for all the good advice guys. I wish I'd had done the timing and GSK in two steps but then you know what they say about hind sight!

One thing I did notice right after the GSK install was that it takes more force to mash the pedal down. Is this expected? I'm getting full travel of the cable and it's not sticking....just takes my force.

Can the addition of the 3K GSK change the relationship (adjustment) between the Gov arm and plate? The #8 plate is now back in the same place as it was prior to the GSK and timiming (when it was making better low end boost).

How does a Zero plate stack up compared to the TST #8 plate? Or compared to a #10 or 100 plate?

Don

 

0 plate is pretty much a full fueling plate. The only difference between a 0 and a 100 is the 100 has alittle lip at the bottom that holds off full fueling down real low (tranny saver), the 100 or 0 should be a nice upgrade from the 8 plate.

 

Thanks for the reply Box5!

 

just doi what i did and yank the plate out , lol.... i can touch 45 psi with the stock turbo (uhoh ) i can do that in any rpm, any time loaded or unloaded. I also have a few other supporting mods though.....

 

So did you put your stock plate back in?? In factory position, or full forward??

 

no i haqve the afc removed, and the plate removed!!! it runs so good! lol, its really smokey though, thats the only issue that i have... With the big injectors i wold say i should upgrade the charger because it does not cool the egts and 45 psi(usable up to 35psi and that is pushing it) is a bit too much but i dont push it that hard due to the fuel consuption at wot.....

 

i purchased my fuel plate in person at TST in columbus, indiana. i was talking to them about a 3k GSK and they said the only fuel plate they sold that they would recomend for use with a GSK was thier #4 plate. they said the others wouldn't fuel right with the addition of a 3 or 4K GSK. if you bought your plate from them, they will trade you for another for way less than the cost of a new one.