Henry Cone
Enthusiast
Weight Reduction For \'96 - \'97 GTS\'s and \'97 RT/10\'s - Long
We decided to go after some weight reduction on both of our '96 GTS's as one of our winter projects. It turned out to be more involved than I originally thought but also provided more benefits than I expected.
The '96 - '97 GTS's and '97 RT/10's were the first of the Gen II cars. They all have cast iron exhaust manifolds as built by CAAP. Starting in '98 all cars received stainless steel tubing manifolds. This was apparently does primarily for weight reduction as no power changes were ever stated for the '98 + cars.
We were able to get used take off '98 + manifolds from Archer Racing for a reasonable price. Since it turns out that the joint between the manifold and the connecting exhause pipe (this is the piece with the flex joints and cats) is different from the original '96 exhaust I also got take off connecting pipes from Archer Racing. I also got the clamps that are correct for '98 + as the method used to connect the manifolds to the primary exhaust pipe is entirely different.
Since the take off primary pipes did not have the cats (they had been cut off and recycled) and since I already was going to have everything apart anyway we decided to upgrade the cats while we were doing everything else. Jon B provided 2 sets of Random Technologies hi-flo cats. These came with adapters for their inlets to match up to the stock primary exhause pipes.
Swapping the stock cast iron manifolds for the newer tubing ones was not too difficult. Since the header flange was much thinner on the '98 + manifolds the stock manifold bolts were now too long. They bottomed in the heads before they clamped the manifolds to the heads tightly. The low cost fix was to add 2 5/16" flat washers under the stock domed washer to make up for the difference.
It also turns out that the exhaust heat shields from '98 + are different from the earlier Gen II ones that were on our cars. We found this by damaging one of the shields on one of our cars. On the other car we got a set of '98 + take off heat shields, again from Archer Racing.
Since we previously had added the Borla system we removed the stock primary pipe and saved it (we now have the complete stock exhause systems for 2 cars in boxes for posterity). To match up the Borla system to the 3" outlet from the hi-flo cats we simply sawed off the portion of the Borla system right in front of the side sill mufflers as this is where the pipe size is reduced to match up to the stock cats. We then butt welded the hi-flo cats in front of the Borla mufflers.
We then sawed off the '98 + primary exhuast pipes (the part with the flex joint) right where the stock cats were originally welded in palce. We then slipped the 2 1/2' to 3" adapter that came with the hi-flo cats over this stock pipe (it is about 2 3/8" OD) and welded these pieces together.
We left the joint where the adapter slides into the front of the hi-flo cats unwelded to make installation and removal easier. We sawed some splits into the front of the hi-flo cats and used some 3" clamps that we got directly from Borla to clamp this joint tightly.
Again this set up allows us to remove or install the exhaust system in the side sills without having to removed the entire Borla system. We thought that this might be beneficial in case of future changes.
The net out of all of thie work?? Well the weights for the parts are as follows:
'96 - '97 cast iron exhaust manifolds = 43.0 lbs per pair
'98 + stainless steel tubing exhause manifolds - 17.5 lbs per pair
'96 - '97 stock primary exhaust pipe with cats and clamps - 35.0 lbs per pair
'98 + primary exhaust pipe with hi-flo cats and clamps - 23.0 lbs per pair
The net savings is 37.5 lbs!!!!!!!! Not a bad weight reduction!!
And the best part?? We dyno'ed my car during our Carolinas Region Dyno Day. It picked up 17 RW HP and 23 RW lb-ft torque (both SAE corrected) from this change. We had made no other changes to the car and ran it on the same dyno as last year before these changes were made.
Not a bad upgrade!!! So my car is now 37.5 lbs lighter and now makes 454 RW HP and 504 RW lb-ft torque with only K&N's, Mopar smooth tubes, a Borla cat-back exhauset, and this manifold and cat change!!!
We decided to go after some weight reduction on both of our '96 GTS's as one of our winter projects. It turned out to be more involved than I originally thought but also provided more benefits than I expected.
The '96 - '97 GTS's and '97 RT/10's were the first of the Gen II cars. They all have cast iron exhaust manifolds as built by CAAP. Starting in '98 all cars received stainless steel tubing manifolds. This was apparently does primarily for weight reduction as no power changes were ever stated for the '98 + cars.
We were able to get used take off '98 + manifolds from Archer Racing for a reasonable price. Since it turns out that the joint between the manifold and the connecting exhause pipe (this is the piece with the flex joints and cats) is different from the original '96 exhaust I also got take off connecting pipes from Archer Racing. I also got the clamps that are correct for '98 + as the method used to connect the manifolds to the primary exhaust pipe is entirely different.
Since the take off primary pipes did not have the cats (they had been cut off and recycled) and since I already was going to have everything apart anyway we decided to upgrade the cats while we were doing everything else. Jon B provided 2 sets of Random Technologies hi-flo cats. These came with adapters for their inlets to match up to the stock primary exhause pipes.
Swapping the stock cast iron manifolds for the newer tubing ones was not too difficult. Since the header flange was much thinner on the '98 + manifolds the stock manifold bolts were now too long. They bottomed in the heads before they clamped the manifolds to the heads tightly. The low cost fix was to add 2 5/16" flat washers under the stock domed washer to make up for the difference.
It also turns out that the exhaust heat shields from '98 + are different from the earlier Gen II ones that were on our cars. We found this by damaging one of the shields on one of our cars. On the other car we got a set of '98 + take off heat shields, again from Archer Racing.
Since we previously had added the Borla system we removed the stock primary pipe and saved it (we now have the complete stock exhause systems for 2 cars in boxes for posterity). To match up the Borla system to the 3" outlet from the hi-flo cats we simply sawed off the portion of the Borla system right in front of the side sill mufflers as this is where the pipe size is reduced to match up to the stock cats. We then butt welded the hi-flo cats in front of the Borla mufflers.
We then sawed off the '98 + primary exhuast pipes (the part with the flex joint) right where the stock cats were originally welded in palce. We then slipped the 2 1/2' to 3" adapter that came with the hi-flo cats over this stock pipe (it is about 2 3/8" OD) and welded these pieces together.
We left the joint where the adapter slides into the front of the hi-flo cats unwelded to make installation and removal easier. We sawed some splits into the front of the hi-flo cats and used some 3" clamps that we got directly from Borla to clamp this joint tightly.
Again this set up allows us to remove or install the exhaust system in the side sills without having to removed the entire Borla system. We thought that this might be beneficial in case of future changes.
The net out of all of thie work?? Well the weights for the parts are as follows:
'96 - '97 cast iron exhaust manifolds = 43.0 lbs per pair
'98 + stainless steel tubing exhause manifolds - 17.5 lbs per pair
'96 - '97 stock primary exhaust pipe with cats and clamps - 35.0 lbs per pair
'98 + primary exhaust pipe with hi-flo cats and clamps - 23.0 lbs per pair
The net savings is 37.5 lbs!!!!!!!! Not a bad weight reduction!!
And the best part?? We dyno'ed my car during our Carolinas Region Dyno Day. It picked up 17 RW HP and 23 RW lb-ft torque (both SAE corrected) from this change. We had made no other changes to the car and ran it on the same dyno as last year before these changes were made.
Not a bad upgrade!!! So my car is now 37.5 lbs lighter and now makes 454 RW HP and 504 RW lb-ft torque with only K&N's, Mopar smooth tubes, a Borla cat-back exhauset, and this manifold and cat change!!!
