IvanAtSPRacing
02-09-2005, 09:50 PM
After making 502 WHP with the twins S13 R&D car we decided to get some video of it on the street. We had been running 25.5 psi on the dyno and the clutch was slipping in 4th gear so we decided to turn the boost down. I turned the MBC out 1.5 turns and headed out for the street.
1st and 2nd gear were usless and third spun pretty bad also. After about half a dozen blasts down the road paying attention to keeping the car straight, I noticed the boost gauge was getting pinned (30+ psi).... oooppppsssssssss. I couldnt believe that a 25 degree drop in tempature could throw the MBC that far off. I turned the boost down to a respecable 24 psi and had some fun.
Since the little jaunt on the street, I noticed that when ever the car was left outside for a period of time and it got really cold, the motor had a tick to it, but when the car was inside the shop all night, when we started it in the morning, no tick. Various ideas were tossed out reguarding what the noise might be. Valve lash might be off, forged piston slap, rod knock were all brought up, but to me it just sounded different.
I needed to change the clutch on the car, I need to upgrade valve springs and retainers for cams I am planning on installing, and I really wanted to see how the motor was holding up, so I decided on pulling the motor and doing a full dissassemble.
We yanked the motor yesterday and dissassembled it today. Prior to pulling the head, we checked valve shim and found it to be in spec. Pulled the head off and pistons looked perfect. Pulled the pan and found everything in order. I was a little stumped as to where the noise might be coming from. Then I noticed it. With No.2 and 3 pistons at TDC I could see that No.3 piston sat just a bit lower then No.2. About 1/16" I flipped the motor over and looked closly at the rod and I could see that it was now slightly S shaped.
http://www.phatka-t.com/bentrod01.JPG
http://www.phatka-t.com/bentrod02.JPG
As you can see by the straight lines drawn on the pictures, the rods are bent both ways which basically shortened the length. I believe that the piston was slapping while the motor was cold due to misalignment.
The rods are stock KA S13s that have been shotpeened and have upgraded ARP rod bolts. I believe the HP level we were at (at 30+ psi) was in the neighborhood of 550 whp.
Just another informative post from your friends at PhatKA-T
1st and 2nd gear were usless and third spun pretty bad also. After about half a dozen blasts down the road paying attention to keeping the car straight, I noticed the boost gauge was getting pinned (30+ psi).... oooppppsssssssss. I couldnt believe that a 25 degree drop in tempature could throw the MBC that far off. I turned the boost down to a respecable 24 psi and had some fun.
Since the little jaunt on the street, I noticed that when ever the car was left outside for a period of time and it got really cold, the motor had a tick to it, but when the car was inside the shop all night, when we started it in the morning, no tick. Various ideas were tossed out reguarding what the noise might be. Valve lash might be off, forged piston slap, rod knock were all brought up, but to me it just sounded different.
I needed to change the clutch on the car, I need to upgrade valve springs and retainers for cams I am planning on installing, and I really wanted to see how the motor was holding up, so I decided on pulling the motor and doing a full dissassemble.
We yanked the motor yesterday and dissassembled it today. Prior to pulling the head, we checked valve shim and found it to be in spec. Pulled the head off and pistons looked perfect. Pulled the pan and found everything in order. I was a little stumped as to where the noise might be coming from. Then I noticed it. With No.2 and 3 pistons at TDC I could see that No.3 piston sat just a bit lower then No.2. About 1/16" I flipped the motor over and looked closly at the rod and I could see that it was now slightly S shaped.
http://www.phatka-t.com/bentrod01.JPG
http://www.phatka-t.com/bentrod02.JPG
As you can see by the straight lines drawn on the pictures, the rods are bent both ways which basically shortened the length. I believe that the piston was slapping while the motor was cold due to misalignment.
The rods are stock KA S13s that have been shotpeened and have upgraded ARP rod bolts. I believe the HP level we were at (at 30+ psi) was in the neighborhood of 550 whp.
Just another informative post from your friends at PhatKA-T