Engine/Transmission (1994 - 1998) 3K GSK lowered boost with #6 plate

[tgrfan2]

A search here and in the accessories area did not cover what I need to know. I recently had a DTT upgrade. DTT recommended the 3K GSK and up timing to 15. 5. We did this and I like the way the truck runs except that the max boost I get loaded now is 22-24#. It was 28-30# before timing adjustment from 14. 0 and adding 3K GSK. With the stock transmission, I had to limit boost to 22-24# to avoid slip in OD loaded so I am basically back at usable power loaded before transmission upgrade.

I checked with Mark at TST and he said that is why they don't recommend a #6 with GSK but to remove the hose to the waste gate and see if I get more boost. I get 30-32# with it removed so an adjustable boost elbow might help according to Mark.

I know many on TDR recommend the #10 with GSK. According to the chart the #10 only produces 570# in a 98 auto. I am used to the 635# rating of the #6 and don't want to go backwards with a new transmission. I tow against an 06 D/A Z and with a 2003 HO and want to stay ahead!

Would those that tow heavy recommend "fixing" the #6 with the adjustable elbow or would a #5 be a better choice? I did not find much difference in EGTs at 2000 rpm with the GSK change, but at 2700rpm under load or unloaded acceleration I can get above 1300 real quick so it would seem I am getting plenty of fuel at least at higher rpms.

Basically what I am trying to do is keep my power up at the normal cruising rpm of 2-2100 rpm and avoiding downshifts loaded (20-21K GCW) on most "normal" hills as I did before adding the 3K GSK.

Thanks for any help.

 

[K5IP]

This sounds familiar. My truck is a 95 5spd.

I have some base data on my truck from day one. I recorded max boost pressure at various RPM's (waste gate fooled) to have as a reference for future operation.

When I installed a 3KGSK I liked the increased RPM before defueling, but I also found that my boost, (and thus fueling) at various RPM was down about 4psi from the original data. I found that the GSK spring change can effect how the lever hits the plate and it was necessary for me to advance the plate (original in my case) about . 020" to return to the original boost conditions. I know the #6 plate is not recommended for 3GSK operation, but I suspect it is because of the lever/plate interface changes. You might try moving the plate, try . 020" and give it a try.

Rog

 

[Jim Fulmer]

Adjust the Gov arm up... ... . GSK changes this on all plates to some degree. Saying a #6 won't work is hog wash... ... a 12V is all in the tuning... ..... BOTW, read my signature.



Good Luck, Jim

 

[tgrfan2]

Thanks that does sound like my situation. I had wondered about doing that since I can keep an eye on my egts. i had the wife ride with me a while ago to watch the exhaust. I found I got boost and smoke at about 2700 rpm but the transmission also unlocked about that time so I was making more noise than go. No smoke occurred under hard acceleration in OD unlike before GSK install so I think Mark is right that the GSK affected the fueling in the normal towing rpm of around 2000. I like the extra rpm, but it really doesn't help me towing since the EGTs rise quickly above 2500 rpm. I may take the GSK back off the 98 and put it on my 95 where I can use the unloaded rpm if I can't solve the problem otherwise.

The truck is back at the transmission shop for some linkage and TPS tweaking so it will probably be next weekend before I can play with the plate.

 

[tgrfan2]

Adjust the Gov arm up... ... . GSK changes this on all plates to some degree. Saying a #6 won't work is hog wash... ... a 12V is all in the tuning... ..... BOTW, read my signature.



Good Luck, Jim

Thanks. I can make do with about 1/3 the horses you have!

 

[Jim Fulmer]

400 and below is much more fun! Over 600 is work!



Jim