8lbs on a built 11:1 355
Thread Starter
Joined: Aug 2007
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From: Oshawa, Ontario
8lbs on a built 11:1 355 This will be a heated debate with alot of mixed reviews so before you get all hot and heavy just sit back and if you have some good points to say do so otherwise please keep the trashing to yourself. I had the intentions of running a single intercooler P600B 8lb kit on my car and did the research and found out not such a good idea on a stock bottom end. The FMU is **** and not to run it go with a bigger fuel pump and injectors which i was prepared to do. Anyway needed cash to fund the new motor and sold off the kit to a friend. My friend hasnt touched it and is debating to sell it since its been sitting in the box. I know a stock bottem end cant handle the power and compression was not the best for running at stock 10.5. I have my bottom almost built up and as most of you know its a stock crank with forged mahle pistons and forged eagle h beams running 11:1. The rings were setup for nitrous as thats what i had intended to work for down the road. Already got a walbro 255 and will upgrade to a bigger injector if i buy it back. With a bottom end built up can i run lower boost with a spot on tune? Car as it sits should be around 400rwhp and figure 6-8lbs would probubly set me in the 480-500 range when done. I will not go crazy with the boost as im sure it will be even worse on the street at 400rwhp vs stock let alone in the 500 area.
Im looking for answers as to whether or not even with a better bottom end can i still safely run boost on this motor and IF i were to buy it back what should i do to make it reliable and safe?
Keep the trashing down PLEASE!
Im looking for answers as to whether or not even with a better bottom end can i still safely run boost on this motor and IF i were to buy it back what should i do to make it reliable and safe?
Keep the trashing down PLEASE!
^ Good call. At 11:1, you're going to have a hard time running even 5-ish pounds of boost without detonation, or without having to run race gas.
If you're dead set on the heads you have, you could go for a thicker headgasket. Otherwise, try to swap to a set of heads with larger chambers.
Run some math numbers on the setup you have to confirm a close estimate of your current comp. ratio, and play around with headgasket thickness and/or head chamber size to bump the compression down to around 9.5-10:1. My 383 is set up at 9:1, and I run 15 psi @6500 rpm on all forged internals.
If you bumped down to 10:1, you could run 8# safely with a good tune and probably make upwards of 480-500 rwhp on pump gas.
If you're dead set on the heads you have, you could go for a thicker headgasket. Otherwise, try to swap to a set of heads with larger chambers.
Run some math numbers on the setup you have to confirm a close estimate of your current comp. ratio, and play around with headgasket thickness and/or head chamber size to bump the compression down to around 9.5-10:1. My 383 is set up at 9:1, and I run 15 psi @6500 rpm on all forged internals.
If you bumped down to 10:1, you could run 8# safely with a good tune and probably make upwards of 480-500 rwhp on pump gas.
Thread Starter
Joined: Aug 2007
Posts: 1,368
Likes: 10
From: Oshawa, Ontario
Heads were supposed to be 64cc when i got them and turned out to be 60cc so they have some milling done to them already and currently running a .030 gasket to get me up to 11:1 and iirc when i did the math on a .039 gasket it was around the 10.5 or 10.7 range. Ill be running 94 octane and will not run race gas this is a weekend get in and go warrior not a race car. Alot will have to do with the tune to get it to run right without detonation which i know will take time and money for an awesome tuner. Just throwing the idea around and seeing if my motor is up to the task of running small amount boost on pump gas and proper tune or im asking for trouble and alot of issues?
Last edited by 95mysticta; Feb 22, 2011 at 11:26 AM. Reason: spelling corrected
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From: CT/NJ
Heads were supposed to be 64cc when i got them and turned out to be 60cc so they have some milling done to them already and currently running a .030 gasket to get me up to 11:1 and iirc when i did the math on a .039 gasket it was around the 10.5 or 10.7 range. Ill be running 94 octane and will not run race gas this is a weekend get in and go warrior not a race car. Alot will have to do with the tune to get it to run right without detonation which i know will take time and money for an awesome tuner. Just throwing the idea around and seeing if my motor is up to the task of running small amount boost on pump gas and proper tune or im asking for trouble and alot of issues?
Boost and compression ratio are inversely related. The higher the CR, the less boost you can safely run, and vice versa.
You can run 11:1 compression and run like 3-4 pounds of boost, or 8:1 and run 20 psi for example.
I think at 8 psi, you're living a bit dangerously with the proposed setup. But I'm a conservative overkill builder.
You can run 11:1 compression and run like 3-4 pounds of boost, or 8:1 and run 20 psi for example.
I think at 8 psi, you're living a bit dangerously with the proposed setup. But I'm a conservative overkill builder.
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Thread Starter
Joined: Aug 2007
Posts: 1,368
Likes: 10
From: Oshawa, Ontario
Like i said im entertaining the idea of buying it back and never said im going to go through with it im asking for opinions first. Even i was skeptical just thinking about it but came to right place for more tech info from you guys to see what you think and or reccommend in this situation. Ill leave it and stick with the jug to be on the safer side and have less to worry about driving it and worrying about if it will hold while on it.
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Unless the combustion chambers can be reworked it isn't worth it, and even then who knows how much lower the CR would be. Even then the tune would have to be dead nuts and you would have to discipline yourself not to up the boost once you get bored with the power.
Thread Starter
Joined: Aug 2007
Posts: 1,368
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From: Oshawa, Ontario
Even from what ive heard the P600b kit is maxed out at 8lbs... thats why alot of people dont use if they are going for big numbers as you cant crank the boost up. In my situation i really dont want to go bigger if i did use the kit 500rwhp will be one nasty car and be more better suited for burnout competitions let alone street duty with the tires ill be going through. Bottom line it all comes up to the tune an tuner to see how reliable it can be or even it can be done period. Time will tell this summer how i make out getting the motor the way it sits in the car and tuned.
How reliable are the P600B Single Intercooled setups anyone??? I relize carrying a spare belt is a must but are the blowers and piping quality as ive heard mixed reviews?
How reliable are the P600B Single Intercooled setups anyone??? I relize carrying a spare belt is a must but are the blowers and piping quality as ive heard mixed reviews?
Last edited by 95mysticta; Feb 22, 2011 at 01:29 PM. Reason: spell check
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From: CT/NJ
E85 is an option if it is available in the OPs area and he wanted to convert. Doubtful that is the case though because he is in Canada. No corn farmer gravy train up there AFAIK.
You'll be fine just add a water/meth kit to your setup and run pump gas, I have a 383 sbc running 10.3:1 static with a p1200br and a huge air to air IC along with water/meth blowing thru a carb and I'm running 12# of boost.
You would be fine at 8 lbs. As with ALL boosted vehicles it's ALWAYS IN THE TUNE. Adding ported heads will help keep excessive cylinder pressures at bay. You have to have a good flowing exhaust. If you run a decent sized cam it can allow you to run more boost safely. Your combustion chambers need to be cleaned of ANY burs and hot spot areas, Colder plugs and you're in business. Make sure your A/F is in the 11.7 range and have fun. If you do run race gas like c16 you should be able to run 12-13 lbs.
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Joined: Feb 2006
Posts: 1,025
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From: CT/NJ
You would be fine at 8 lbs. As with ALL boosted vehicles it's ALWAYS IN THE TUNE. Adding ported heads will help keep excessive cylinder pressures at bay. You have to have a good flowing exhaust. If you run a decent sized cam it can allow you to run more boost safely. Your combustion chambers need to be cleaned of ANY burs and hot spot areas, Colder plugs and you're in business. Make sure your A/F is in the 11.7 range and have fun. If you do run race gas like c16 you should be able to run 12-13 lbs.
Ported heads keep excessive cylinder pressure at bay? Perhaps you could share some of the facts you based that conclusion on.
Put a big cam in it so all of the boost blows right thru? I guess that is one way to keep it from knocking, or making any power.
Switching from 82-83 MON pump gas to 117 MON C16 is only going to allow for 4-5 psi more boost? No wonder everyone is so allergic to race gas on here. The guy with the blow thru carb and meth kit is running the same boost...