Cracked rear iron S4
10-28-2007, 09:36 PM
#1
Senior Member
Thread Starter
Join Date: Oct 2004
Location: Oklahoma City
Posts: 233
Hey guys got a question. I know the S4 rear plates are weak but this just amazes me.
Let me give you a little detail on the motor and the situation. Car is a 88 10th AE. 1000 miles on the motor. Good sized street port and exhaust port. Turbo is a 60-1 w/ 84. A/R. Full 3inch 304 stainless exhaust. Front mount intercooler. No a/c, p/s, OMP blocked running premix. Engine management is a Haltech E8. Coils are LS1 coils set up direct fire. Injectors are 550 and 1680.
Anyhow we had our Fall BBQ and Track day I ran the car about 12 times around the track. Wish it was more, but since I was organizing it I couldn't run as much. Always shifted by 6200 rpms since the motor is still new. Max water temps wer 209F. Max intake temps at the elbow before the throtal plates was 122F. No issues until the last trip around.
Car had cooled down. I started it up let it reach 190F. Coming out of the first turn, in 2nd gear, I laid into it shifting again around 6000 rpms give or take 100 rpms. Boost was at 16 psi, A/F was 10.9-11.1, leading timing at 13* trailing split at 12*.
I had 1/2 a tank of gas w/ 1/2 101 and 1/2 91. Air intake temps were 105F and water temp was 192F. Turn was a right hand tight turn so no fuel starvation of the pump. Just before shifting into 3rd I saw the oil pressure drop and smoke everywhere. Got it off the track as fast as possible. Car still idled perfectly and the low oil light came. Shut it down as soon as possible while getting of the track. After inspection I had cracked the rear dowell area below the oil pedistal.
The motor is out of the car and on th engine stand in short block form. Rear plate will come off tomorrow. At this time it does not seem any seals are broken.
Anyone have any ideas???? I am going to try and upgrade to a later s5 iron. I have a S4 rear plate in the garage and may use it until I brake it. I would like to keep this from happening again. Any help is much appreciated. Pictures are on my other computer and will be uploaded tomorrow.
Thanks,
Brad
Let me give you a little detail on the motor and the situation. Car is a 88 10th AE. 1000 miles on the motor. Good sized street port and exhaust port. Turbo is a 60-1 w/ 84. A/R. Full 3inch 304 stainless exhaust. Front mount intercooler. No a/c, p/s, OMP blocked running premix. Engine management is a Haltech E8. Coils are LS1 coils set up direct fire. Injectors are 550 and 1680.
Anyhow we had our Fall BBQ and Track day I ran the car about 12 times around the track. Wish it was more, but since I was organizing it I couldn't run as much. Always shifted by 6200 rpms since the motor is still new. Max water temps wer 209F. Max intake temps at the elbow before the throtal plates was 122F. No issues until the last trip around.
Car had cooled down. I started it up let it reach 190F. Coming out of the first turn, in 2nd gear, I laid into it shifting again around 6000 rpms give or take 100 rpms. Boost was at 16 psi, A/F was 10.9-11.1, leading timing at 13* trailing split at 12*.
I had 1/2 a tank of gas w/ 1/2 101 and 1/2 91. Air intake temps were 105F and water temp was 192F. Turn was a right hand tight turn so no fuel starvation of the pump. Just before shifting into 3rd I saw the oil pressure drop and smoke everywhere. Got it off the track as fast as possible. Car still idled perfectly and the low oil light came. Shut it down as soon as possible while getting of the track. After inspection I had cracked the rear dowell area below the oil pedistal.
The motor is out of the car and on th engine stand in short block form. Rear plate will come off tomorrow. At this time it does not seem any seals are broken.
Anyone have any ideas???? I am going to try and upgrade to a later s5 iron. I have a S4 rear plate in the garage and may use it until I brake it. I would like to keep this from happening again. Any help is much appreciated. Pictures are on my other computer and will be uploaded tomorrow.
Thanks,
Brad
10-30-2007, 09:59 AM
#5
Senior Member
Thread Starter
Join Date: Oct 2004
Location: Oklahoma City
Posts: 233
I have decided to use my RE front and Rear housings and build a hybrid using the RE intake. That should beef it up more and I'll run some different plug wires.
How many rear plates have you broke j9fd3s?
How many rear plates have you broke j9fd3s?
11-03-2007, 01:53 PM
#6
Senior Member
Join Date: May 2002
Location: California
Posts: 22,465
Originally Posted by rotaryinspired' post='886698' date='Oct 30 2007, 07:59 AM
I have decided to use my RE front and Rear housings and build a hybrid using the RE intake. That should beef it up more and I'll run some different plug wires.
How many rear plates have you broke j9fd3s?
How many rear plates have you broke j9fd3s?
1, car was na too
actually paul broke it....
12-12-2007, 11:17 AM
#7
Senior Member
Join Date: Jun 2003
Location: Grand Prairie, TX
Posts: 917
Originally Posted by j9fd3s' post='886666' date='Oct 29 2007, 08:23 PM
ignition... as an example, changing to new ngk wires from old ones, fixed a lot of misfiring on my old t2 and misfire = broken rear housings
+1
B
04-25-2008, 10:30 AM
#8
Member
Join Date: Apr 2008
Posts: 33
You have to dowel the motor, you are putting all the power through 2 dowels, 500hp through a surface area of 1sq cm, it's not enough. We dowel nearly everything especially anything over 300rwhp. We have only had one failure with a dowelled motor cracking and it didn't crack where yours cracked it cracked from the stationary gear hole up and down 70mm per side, a hit with a hammer split the plate in 2 vertically through the centre. The clutch slipped and the motor over reved and the rotor hit the housing.
Get a good dowel job and never worry about it again
It dosen't matter which plate you use they can crack on only 2 dowels
Get a good dowel job and never worry about it again
It dosen't matter which plate you use they can crack on only 2 dowels
07-25-2009, 07:03 PM
#9
Junior Member
Join Date: Aug 2007
Posts: 17
I know i know im really bringing this thread back from the dead..lol but i figured why waste the bandwidth by creating a new thread? So i had a question about these rear irons..i just got a set of the rare thick dowl pin area plates with triangular gusset on the rear dowel. The dowel pin area casting is more then twice as thick on these plates then the old style S4 plates plus the rear plate has that gusset. My question is, is it even possible to crack the dowel area on these enormous casting plates? this motor is gonna be pushing over 600whp which is why i got these plates, but after seeing these plates i dont even think its necessary to dowel the motor because these castings look very very strong..so has anyone ever cracked one of these like the shitty old ones??
11-08-2009, 10:05 PM
#10
Senior Member
Thread Starter
Join Date: Oct 2004
Location: Oklahoma City
Posts: 233
I have one of those exact same plates now. When pushing a lot of power and running it hard I would say anything is possible. I did not dowel the new motor. I did not feel the need. No problems so far w/ lots of abuse.