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Discussion Starter · #1 ·
I'm starting to order parts for my engine build I have a 99 cobra with a procharger I'm on a budget here so bare with me. What the best bang for the buck pistons on the market? I'm ordering also eagle h beam rods reusing my crank also my block and getting my block bored over .020 so what type of piston does everyone usually run and what compression ratio for boost? I might want to keep my stock c/r or maybe bump it too 10:1. Any other info would help just want to be lead in the right direction
 

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Depends on how much boost you want to run. For me I'm running CP -17cc Dish Pistons. These put me at 8.5:1 C/R. I am setup for a decent amount of boost. If you plan on running high boost, generally you want a lower c/r because it lowers knock limit and gives you more room in the combustion chamber for boost.

Setting up for boost, I generally like seeing 9.5:1 or lower. In my opinion, if you are going into the engine and you know you are building for boost then I would shoot for something near an 8.5 to 1 C/R so you can run a solid amount of boost; even if you don't right in the beginning - it at least gives you room to grow. With a lower compression, you can make your power with timing and control your detonation.
 

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Discussion Starter · #3 ·
Depends on how much boost you want to run. For me I'm running CP -17cc Dish Pistons. These put me at 8.5:1 C/R. I am setup for a decent amount of boost. If you plan on running high boost, generally you want a lower c/r because it lowers knock limit and gives you more room in the combustion chamber for boost.

Setting up for boost, I generally like seeing 9.5:1 or lower. In my opinion, if you are going into the engine and you know you are building for boost then I would shoot for something near an 8.5 to 1 C/R so you can run a solid amount of boost; even if you don't right in the beginning - it at least gives you room to grow. With a lower compression, you can make your power with timing and control your detonation.
i want to run any where from 12-16lbs of boost. An also i want to keep it at a c/r10:1 or maybe 9:1 is because i want to hit it with out waiting for boost to build i want to just hit it an go if that made any sense?
 

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i want to run any where from 12-16lbs of boost. An also i want to keep it at a c/r10:1 or maybe 9:1 is because i want to hit it with out waiting for boost to build i want to just hit it an go if that made any sense?
If you are thinking of running 16 lbs of boost on pump gas - I would recommend not running 10:1 compression ratio. I understand what you're saying - you want a car that performs well N/A and you want the boost to supplement it. It's true a Centri blower builds boost with rpm but I would take a lower compression engine just for the safety of it. You can definitely run a 10:1 c/r with boost but I would feel more comfortable if it had low boost which means less power unless you plan on running race gas all the time. If you are shooting for 16lbs then I would really recommend staying under 9.5:1. Based on what you are saying you want out of your car, I think between a 9.5:1 and 9:1 c/r would be great & give you room to expand. Detonation would be easier to control. And You can make decent power on pump gas. And most importantly, it won't feel like a dog when you driving around town.

Your Cobra's B Heads are around a 52cc so I'm thinking a -12cc dish piston would be great since that would put you around 9.3:1 c/r which is high enough that it would feel great when you're cruising around town but it can handle a good amount of boost/power on pump gas.
 

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Discussion Starter · #5 ·
If you are thinking of running 16 lbs of boost on pump gas - I would recommend not running 10:1 compression ratio. I understand what you're saying - you want a car that performs well N/A and you want the boost to supplement it. It's true a Centri blower builds boost with rpm but I would take a lower compression engine just for the safety of it. You can definitely run a 10:1 c/r with boost but I would feel more comfortable if it had low boost which means less power unless you plan on running race gas all the time. If you are shooting for 16lbs then I would really recommend staying under 9.5:1. Based on what you are saying you want out of your car, I think between a 9.5:1 and 9:1 c/r would be great & give you room to expand. Detonation would be easier to control. And You can make decent power on pump gas. And most importantly, it won't feel like a dog when you driving around town.

Your Cobra's B Heads are around a 52cc so I'm thinking a -12cc dish piston would be great since that would put you around 9.3:1 c/r which is high enough that it would feel great when you're cruising around town but it can handle a good amount of boost/power on pump gas.
yeah what im doing is the car is going to run on 93 an also have a race tune but mostly itll be running on 93 i also want my motor to be safe and not a dog on power because it will be driven quite alot and i have a 99 cobra i have the c heads on mine but for a 9:5c/r what pistons should i run? my heads are going to be stock not going to get them ported or anything just going to freshen them up with new valve stem seals might put 96-98 cobra cams and degreeing them but i dont know but for right now whats a type of piston to run for a c/r of 9:5 also people tell me go 5cc dish then other tell me 17cc dish and im lost i dont want to put in the wrong pistons
 

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Running 8:1 compression pistons on a Centrifical boosted car would be a mistake as the car will feel like a turd untill 3000RPM when the blower starts to kick in. MY 01 Cobra has a Vortech and a stock 9:1 short block. Most of the time, just running around town, the motor deos not see boost and if the motor had low compression pistons, street drivability would suffer.

When I rebuild the stock short block and strengthen it with forged rods and pistons, I will choose a flat top piston to improve the power and drivability when the motor is not under boost. A flat top piston will put my 01 Cobra engine around 10.5 :1. Perfect in my opinion for a Vortech boosted 4V.
 

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Running 8:1 compression pistons on a Centrifical boosted car would be a mistake as the car will feel like a turd untill 3000RPM when the blower starts to kick in. MY 01 Cobra has a Vortech and a stock 9:1 short block. Most of the time, just running around town, the motor deos not see boost and if the motor had low compression pistons, street drivability would suffer.

When I rebuild the stock short block and strengthen it with forged rods and pistons, I will choose a flat top piston to improve the power and drivability when the motor is not under boost. A flat top piston will put my 01 Cobra engine around 10.5 :1. Perfect in my opinion for a Vortech boosted 4V.
Do you need valve reliefs on flat tops on our motors? I can't figure out what compression ratio piston to run with my 98 GT pi swap MHS stage 2 heads and cams, long tubes full pi bolt ons, 70mm tb, Vortech V1 kit on 12# 93 octane 450 non intercooled going forged internals possibly terminator shortblock but I wanted to run an intercooler or meth and keep the compression ratio a little higher like the pi swap around 10/1 or so
 
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