S4 Turbo Engine Max Power
11-05-08, 06:36 PM
#1
S4 Turbo Engine Max Power
Ok guys, searched for a while and came up with a lot of intercooler topics, EGR, Build threads, etc. I am wondering about the maximum power/boost of a S4 TII engine. Engine will have a small bridgeport on it. I heard that the rear iron is weak and will crack near the dowel pin area. Any info on this? 
11-06-08, 09:06 AM
#5
Engine, Not Motor
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Irons do not break due to power, they break due to detonation. Most broken irons can be traced back to massive and severe detonation, caused by wildly rich AFRs or ignition misfires due to EMS noise.
Over 400HP will not be an issue. I'm running more then that on my S4 block. Not saying that the S5 irons are a worthless upgraded because if you have them, use them.
Also don't waste too much time on a "small" bridgeport. Either half bridge it properly, or go to a full bridge.
You also don't need a bridgeport to make 400HP. I'd suggest sticking with a street port so you can get decent gas mileage and have a car which is much easier to tune (ie. it actually pulls vacuum).
Over 400HP will not be an issue. I'm running more then that on my S4 block. Not saying that the S5 irons are a worthless upgraded because if you have them, use them.
Also don't waste too much time on a "small" bridgeport. Either half bridge it properly, or go to a full bridge.
You also don't need a bridgeport to make 400HP. I'd suggest sticking with a street port so you can get decent gas mileage and have a car which is much easier to tune (ie. it actually pulls vacuum).
11-06-08, 09:16 AM
#6
I detonated the living daylights out of my s4 irons and never cracked them. People do have more problems over 400whp though, mostly because those motors are running on the edge. I have recently switched to s5 irons for this motor I am building. When comparing the casting around the dowel pin landings, I have concluded that these particular irons are about 20% thicker in that area (both front and rear). Not all s5 irons are made the same though. These particular ones came out of a JDM 91 turbo engine.
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