HP from road racing LB9?
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Junior Member
Joined: Mar 2000
Posts: 21
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From: Baltimore, Md
HP from road racing LB9?
I have a LB9 in a 91 1LE(the 230 HP version). Car used in road racing only. Mods include Ed Wright chip, airfoil, open exhaust, all smog removed, coil, MSD. I'm looking at how my lap times and top speeds compared to different classes (AS mainly, but almost totally "stock" classes as well) and the costs of engine mods to run those classes.
Got a good handle on it all, but the only unknown is how much HP am I currently making??????
Thanks.....
------------------
91 1LE
305 LB9 5-Speed, Dana-44
AutoPower 6-pt Cage, Koni adjustables, Polyurethane bushings, MSD6AL, Crane coil, TPS Airfoil, K&N filters, Fastchip, Taylor Pro 409 wires, Grant, Airquip, Performance Friction, Jazz, Autometer, Centerlines, 10LB Halon
Got a good handle on it all, but the only unknown is how much HP am I currently making??????
Thanks.....
------------------
91 1LE
305 LB9 5-Speed, Dana-44
AutoPower 6-pt Cage, Koni adjustables, Polyurethane bushings, MSD6AL, Crane coil, TPS Airfoil, K&N filters, Fastchip, Taylor Pro 409 wires, Grant, Airquip, Performance Friction, Jazz, Autometer, Centerlines, 10LB Halon
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Joined: Jan 2000
Posts: 19,664
Likes: 313
91,
I'm guessing your season is just about over. Even with the manual, the "better" cam in the LB9 isn't quite enough to let it breathe well. Contrary to what you may have heard, you can install larger valves in a 305 with some success. One key is to keep the valve face margins small, and radius the front edges. You'd also need to unshroud the valves at the chambers sides a bit.
A dual-pattern cam grind favoring the exhaust can help. You have all winter to do your homework and research, then select a cam profile that is right for your RPM range. Roller-tip or full roller rockers will lower friction, provide more accurate and reliable valve action, and reduce temperatures.
You should also consider opening the restrictions in the intake plenum behind the throttle body, and try matching the plenum opening and intake base ports to the runners as best you can. Once you start changing the intake air flow more significantly, you'll need to do something about fuel delivery. An adjustable fuel pressure regulator will give you a little more control over that.
I hope you're running a much colder thermostat than the stock 195°F unit, especially with the aftermarket PROM.
All of these changes are relatively invisible, so unless the inspections are super-critical, you shouldn't have any difficulty qualifying in the class.
I'm not sure what Wright's programming is doing for you, but the lack of exhaust pressure and the airfoil are probably helping flow a little at upper RPM ranges. A wild guess would be a 10-15 HP increase over the stock configuration - peak.
------------------
Later,
Vader
------------------
"Make Me Bad"
Adobe Acrobat Reader 4.0
I'm guessing your season is just about over. Even with the manual, the "better" cam in the LB9 isn't quite enough to let it breathe well. Contrary to what you may have heard, you can install larger valves in a 305 with some success. One key is to keep the valve face margins small, and radius the front edges. You'd also need to unshroud the valves at the chambers sides a bit.
A dual-pattern cam grind favoring the exhaust can help. You have all winter to do your homework and research, then select a cam profile that is right for your RPM range. Roller-tip or full roller rockers will lower friction, provide more accurate and reliable valve action, and reduce temperatures.
You should also consider opening the restrictions in the intake plenum behind the throttle body, and try matching the plenum opening and intake base ports to the runners as best you can. Once you start changing the intake air flow more significantly, you'll need to do something about fuel delivery. An adjustable fuel pressure regulator will give you a little more control over that.
I hope you're running a much colder thermostat than the stock 195°F unit, especially with the aftermarket PROM.
All of these changes are relatively invisible, so unless the inspections are super-critical, you shouldn't have any difficulty qualifying in the class.
I'm not sure what Wright's programming is doing for you, but the lack of exhaust pressure and the airfoil are probably helping flow a little at upper RPM ranges. A wild guess would be a 10-15 HP increase over the stock configuration - peak.
------------------
Later,
Vader
------------------
"Make Me Bad"
Adobe Acrobat Reader 4.0
Last edited by Vader; Mar 31, 2018 at 09:43 PM. Reason: Updated links
Thread Starter
Junior Member
Joined: Mar 2000
Posts: 21
Likes: 0
From: Baltimore, Md
Vadar, thanks for all the info. I learn something everytime I get in this site.
Our last race this year is this weekend. All I have to do is finish and I win the Camaro Mustang Challenge Championship (my 1st year racing...). Then its decision time. I want to run AS but can't really afford to. CMC requires 230 HP max at the rear wheels. Thats why I wanted a idea of what I run now (nobody checked the cars this year). Can't stand the thought of spending the winter working on slowing the car by backing out HP.
Thanks again for the info.
Our last race this year is this weekend. All I have to do is finish and I win the Camaro Mustang Challenge Championship (my 1st year racing...). Then its decision time. I want to run AS but can't really afford to. CMC requires 230 HP max at the rear wheels. Thats why I wanted a idea of what I run now (nobody checked the cars this year). Can't stand the thought of spending the winter working on slowing the car by backing out HP.
Thanks again for the info.
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