Also it is heading to Van Nuys next weekend for Spring Fling.
Stock exhaust manifolds vs headers
- Thread starter tandart66
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tandart66
Active Member
I want to have the peak power band around 3.5-4.5k rpm and 5.5-6k redline (Im used to alot more high revving engines than the SL6 so if this is too high I apologize). I'm not sure what cam specs to use, I plan to have a custom grind by a local cam specialist and all of that is still up in the air. Since my machinest hasn't yet determined how much overbore the block needs to just clean it up, I haven't yet run any compression calculations.
Peak power (hp) or torque ? That's stock mild manner range, Stock is around 4,000 so anything above will start to increasing the powerband, 4,500-5,000 rpm is a good streetable peak hp rpm and peak torque is generally 1000-1500 rpms lower.
You have typically 500 or rpms about peak hp where power starts to drop off dramatically especially with poor flowing heads.
tandart66
Active Member
I was looking at hp, I had no idea that it makes peak hp that high! Generally what cam specs would be optimal for that rpm range? I'm heading to the machine shop today to talk with my machinist, so hopefully we can figure out what needs to be done to reach that 9.5:1 CR, and get a cam grind to match.
You got a pretty lite car so that's good, what gears are you gonna run and you going to add a decent stall?
You probably want something in the 210-225 @ fifty intake duration, kind of depends on you.
Just keep in mind it is only 225 cubes so it will never be a power house without forced induction. Also the head sucks on the slant so don’t go crazy with a cam, it will be gasping for air without lots of head magic.
I would look at Oregon Cams 2106 or 819 grinds with the latter being a bit more aimed at higher rpm. Ask to have the LCA ground at 106 for both these grinds. The poor head flow needs a low LCA to make max power under the curve (Vizard). I have one with the 2106 at 106 LCA and 8.9:1 and the next one will be a 4 speed OD with an 819 at 106 LCA at 9.4:1. Those compressions give you about 185 PSI for a cranking compression for those cams/compression ratio about all I would run for my driving. I took 0.060 off the head and once assembled the pistons will be measured in the hole and the head chamber volume required to hit 9.4:1 calculated and the head decked until that volume is achieved
Mine is getting oversized valves and with the 819 helps with a bit more at higher RPM.
The Dutra Duals will help tremendously IF you put the Y collector behind the transmission cross member where it will give it a big kick in torque down lower (2500 RPM). All you need is 1 5/8 from the duals to the Y as you are only feeding it with 3 cylinders. You may get a tiny bit more power with larger pipes but the aggravation of running larger than 1 5/8 is barely worth it. Doug said headers will perform marginally better at the dragstrip at WOT. For the most power under the entire curve the split front and rear banks of three with a Y as far back as possible is best. He had one near the rear axle and he said it pulled hard down at 1800 RPM
I would look at Oregon Cams 2106 or 819 grinds with the latter being a bit more aimed at higher rpm. Ask to have the LCA ground at 106 for both these grinds. The poor head flow needs a low LCA to make max power under the curve (Vizard). I have one with the 2106 at 106 LCA and 8.9:1 and the next one will be a 4 speed OD with an 819 at 106 LCA at 9.4:1. Those compressions give you about 185 PSI for a cranking compression for those cams/compression ratio about all I would run for my driving. I took 0.060 off the head and once assembled the pistons will be measured in the hole and the head chamber volume required to hit 9.4:1 calculated and the head decked until that volume is achieved
Mine is getting oversized valves and with the 819 helps with a bit more at higher RPM.
The Dutra Duals will help tremendously IF you put the Y collector behind the transmission cross member where it will give it a big kick in torque down lower (2500 RPM). All you need is 1 5/8 from the duals to the Y as you are only feeding it with 3 cylinders. You may get a tiny bit more power with larger pipes but the aggravation of running larger than 1 5/8 is barely worth it. Doug said headers will perform marginally better at the dragstrip at WOT. For the most power under the entire curve the split front and rear banks of three with a Y as far back as possible is best. He had one near the rear axle and he said it pulled hard down at 1800 RPM
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