aftermarket heads
Thread Starter
Member
Joined: Jul 2000
Posts: 179
Likes: 0
From: Lake Oswego, OR, USA
aftermarket heads
If i get aftermarket aluminum heads for the 350 i'm getting, will they raise my peak torque if i keep the stock compression ratio?
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1991 Z28 305 5spd 1LE, TES headers, dual cats, 3 Chamber flowmaster, Comp cams .488/.495 212/218 the usual street racer with a stock chip.
Gained 20HP by porting and polishing my EGR passage.
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1991 Z28 305 5spd 1LE, TES headers, dual cats, 3 Chamber flowmaster, Comp cams .488/.495 212/218 the usual street racer with a stock chip.
Gained 20HP by porting and polishing my EGR passage.
Joined: Mar 2000
Posts: 43,187
Likes: 43
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
It's not an easy question, because there are a lot of different aluminum aftermarket heads out there, and torque is affected by a lot more than compression ratio.
For instance, AFR 220's would tend to reduce low end torque vs. AFR 190's, even though they both have the same chamber size and therefore would have the same compression. Valve size can affect torque, etc.
So, you'll have to be a little more specific before a real answer can be given to your question. But, aluminum transfers heat more readily, so power (which starts with torque) is actually reduced when the compression ratio is the same as a cast iron head, all other things being equal.
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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. Cat-back from '91 GTA, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker headers & y-pipe, 3" Catco cat & 3" cat-back).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Edelbrock 1901 Q-Jet, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).
For instance, AFR 220's would tend to reduce low end torque vs. AFR 190's, even though they both have the same chamber size and therefore would have the same compression. Valve size can affect torque, etc.
So, you'll have to be a little more specific before a real answer can be given to your question. But, aluminum transfers heat more readily, so power (which starts with torque) is actually reduced when the compression ratio is the same as a cast iron head, all other things being equal.
------------------
82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. Cat-back from '91 GTA, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker headers & y-pipe, 3" Catco cat & 3" cat-back).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Edelbrock 1901 Q-Jet, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).
Member
Joined: Apr 2000
Posts: 307
Likes: 0
From: Frederick, MD USA
Whoa! How did you gain 20 hp by porting the EGR pasages??? I've never even heard of this before..Tell me more!!
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I am looking to buy Edelbrock T.E.S. headers with the y-pipe. I am also looking for a 3.42 - 3.55 posi disc rear. cheesy@fred.net is my e-mail, send a letter if you can help!
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- Red '88 IROC 305 TPI T-5 w/3.08
- Accel 300+ Ignition
- Accel 300+ Pro Sleeve Plug Wires
- AC Delco Rapid Fire Plugs
- Dual Friction Stage III Centerforce Clutch
- Energy Suspension Transmission Mount
- Flowmaster Force II 3 Chamber Cat Back Exhaust
- Gutted Airboxes
- Hypertech Stage II PROM
- Hypertech Airfoil
- Throttle Body Coolant Bypass
- Best Maryland (40 degrees) E/T 14.686, 60' 2.205, 1/8th mile 9.461, 1/4 mile MPH 93.91
- Best Florida (80 degrees) E/T 14.88, 60' 2.163, 1/8th mile 9.540, 1/4 mile MPH 92.74
- Best 60' 2.163(Florida)
- TPiS AFPR set to 42psi using Accel Fuel Pressure Gauge (Installed after Maryland run)
- Aluminum Driveshaft (Installed after Maryland run)
I am looking to buy Edelbrock T.E.S. headers with the y-pipe. I am also looking for a 3.42 - 3.55 posi disc rear. cheesy@fred.net is my e-mail, send a letter if you can help!
Member
Joined: Apr 2000
Posts: 307
Likes: 0
From: Frederick, MD USA
Back to the top..I wanna know more about this!
------------------
I am looking to buy Edelbrock T.E.S. headers with the y-pipe. I am also looking for a 3.42 - 3.55 posi disc rear. cheesy@fred.net is my e-mail, send a letter if you can help!
------------------
- Red '88 IROC 305 TPI T-5 w/3.08
- Accel 300+ Ignition
- Accel 300+ Pro Sleeve Plug Wires
- AC Delco Rapid Fire Plugs
- Dual Friction Stage III Centerforce Clutch
- Energy Suspension Transmission Mount
- Flowmaster Force II 3 Chamber Cat Back Exhaust
- Gutted Airboxes
- Hypertech Stage II PROM
- Hypertech Airfoil
- Throttle Body Coolant Bypass
- Best Maryland (40 degrees) E/T 14.686, 60' 2.205, 1/8th mile 9.461, 1/4 mile MPH 93.91
- Best Florida (80 degrees) E/T 14.88, 60' 2.163, 1/8th mile 9.540, 1/4 mile MPH 92.74
- Best 60' 2.163(Florida)
- TPiS AFPR set to 42psi using Accel Fuel Pressure Gauge (Installed after Maryland run)
- Aluminum Driveshaft (Installed after Maryland run)
I am looking to buy Edelbrock T.E.S. headers with the y-pipe. I am also looking for a 3.42 - 3.55 posi disc rear. cheesy@fred.net is my e-mail, send a letter if you can help!
Thread Starter
Member
Joined: Jul 2000
Posts: 179
Likes: 0
From: Lake Oswego, OR, USA
Maybe i should changed that...
------------------
1991 Z28 305 5spd 1LE, TES headers, dual cats, 3 Chamber flowmaster, Comp cams .488/.495 212/218, 187 head castings with bigger valves, self-burned eproms.
Gained 20HP by porting and polishing my EGR passage.(some people take this seriously)
All work done by myself, and proud of it!
Find a .bin on the internet and want it burned? I'll do it for you!
------------------
1991 Z28 305 5spd 1LE, TES headers, dual cats, 3 Chamber flowmaster, Comp cams .488/.495 212/218, 187 head castings with bigger valves, self-burned eproms.
Gained 20HP by porting and polishing my EGR passage.(some people take this seriously)
All work done by myself, and proud of it!
Find a .bin on the internet and want it burned? I'll do it for you!
Member
Joined: Apr 2000
Posts: 307
Likes: 0
From: Frederick, MD USA
Oh..you were kidding..sarcasm is tough to detect on the Internet dude. Damnit! I wanted 2 tenths from porting my EGR passage! Oh well..
------------------
I am looking to buy Edelbrock T.E.S. headers with the y-pipe. I am also looking for a 3.42 - 3.55 posi disc rear. cheesy@fred.net is my e-mail, send a letter if you can help!
------------------
- Red '88 IROC 305 TPI T-5 w/3.08
- Accel 300+ Ignition
- Accel 300+ Pro Sleeve Plug Wires
- AC Delco Rapid Fire Plugs
- Dual Friction Stage III Centerforce Clutch
- Energy Suspension Transmission Mount
- Flowmaster Force II 3 Chamber Cat Back Exhaust
- Gutted Airboxes
- Hypertech Stage II PROM
- Hypertech Airfoil
- Throttle Body Coolant Bypass
- Best Maryland (40 degrees) E/T 14.686, 60' 2.205, 1/8th mile 9.461, 1/4 mile MPH 93.91
- Best Florida (80 degrees) E/T 14.88, 60' 2.163, 1/8th mile 9.540, 1/4 mile MPH 92.74
- Best 60' 2.163(Florida)
- TPiS AFPR set to 42psi using Accel Fuel Pressure Gauge (Installed after Maryland run)
- Aluminum Driveshaft (Installed after Maryland run)
I am looking to buy Edelbrock T.E.S. headers with the y-pipe. I am also looking for a 3.42 - 3.55 posi disc rear. cheesy@fred.net is my e-mail, send a letter if you can help!
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