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10.5 :1 compression ratio??

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They are for engines that run E85. If you run E85 all the time, you'll love them. If you run 91 octane, you'll hate them.
 
i bough a set of 10.5 :1 cp forged pistons without knowing alot about compression ratios on turbo application and ive heard alot both good things and bad things and im a little bit conserned now to be honest, a friend told me to get bigger cams, i was running bc 272/272 he told me to run like 276's or 280's so the engine could "breath" better.. i dont know ..
 
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i bough a pair of 10.5 :1 cp forged pistons without knowing alot about compression ratios on turbo application and ive heard alot both good things and bad things and im a little bit conserned now to be honest, a friend told me to get bigger cams, i was running bc 272/272 he told me to run like 276's or 280's so the engine could "breath" better.. i dont know ..

I think you should start by detailing what you have on the car already. Fill out the vehicle profile. Then explain what you would like to use the car for. 280s in a drag car make a lot of sense. 280s with a 16g and you use the car to get groceries are gonna leave you disappointed. Go into detail on what you have now and what you want to use the car for. It'll be very difficult to help without that info.
 
As above. We can't tell you anything without knowing what you want from the car. BC 280s aren't enormous, but not the best choice for a daily driver. And I hope you didn't buy a pair of pistons - you need a set of 4.
 
I think you should start by detailing what you have on the car already. Fill out the vehicle profile. Then explain what you would like to use the car for. 280s in a drag car make a lot of sense. 280s with a 16g and you use the car to get groceries are gonna leave you disappointed. Go into detail on what you have now and what you want to use the car for. It'll be very difficult to help without that info.

As above. We can't tell you anything without knowing what you want from the car. BC 280s aren't enormous, but not the best choice for a daily driver. And I hope you didn't buy a pair of pistons - you need a set of 4.

Thanks for the reply man, just created the car profile , i bought them 10.5:1 basically without knowing how compression works now im trying to build the best i can with what i have, the car will be mostly for going to car meets in the weekends that kind of thing . I know that a lot of it will depend on the tune .. i just wanted a clean car with couple of nice mods that could keep up with v8's mustangs LOL but reliable.. i already did all the maintance, gaskets, oils ,timming components water and oil pump etc
 
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Thanks for the reply man, just created the car profile , i bought them 10.5:1 basically without knowing how compression works now im trying to build the best i can with what i have, the car will be mostly for going to car meets in the weekends that kind of thing . I know that a lot of it will depend on the tune .. i just wanted a clean car with couple of nice mods that could keep up with v8's mustangs LOL but reliable.. i already did all the maintance, gaskets, oils ,timming components water and oil pump etc

This tells us pretty much nothing about what you're trying to do, unfortunately. I would suggest going with something in the 8.5:1 area, since the 10.5:1 pistons require a big supporting cast to work properly, and it doesn't sound like you want to do something drastic. Basically you have to commit to running E85 all the time for it to work, and that really only benefits you if you're going for big power numbers, with a big turbo. If you run this high compression on 91 octane fuel, you will be severely limited in the amount of ignition timing and boost that you can run - the risk of detonation is significantly higher on this compression, and that could be the end of your engine.
 
Thanks for the reply man, just created the car profile , i bought them 10.5:1 basically without knowing how compression works now im trying to build the best i can with what i have, the car will be mostly for going to car meets in the weekends that kind of thing . I know that a lot of it will depend on the tune .. i just wanted a clean car with couple of nice mods that could keep up with v8's mustangs LOL but reliable.. i already did all the maintance, gaskets, oils ,timming components water and oil pump etc

I am not familiar with fuel in Puerto Rico but using the US government alternate fuels map, they say you have 0 E85 stations available there. That is gonna make 10.5:1 insanely expensive to run if not impossible if you have limited access to good fuel. As stated above, those pistons probably aren't for you. And if messing with v8s and going to meets is the extent of your desires for the car a built motor probsbly isn't even necessary. Do the basic maintence like you have said, get ECMlink and supporting fuel mods and enjoy the car.
 
Hello guys im new here this is my first post so far.. have anyone ever ran 10.5:1 compresion ratio? If so.. what was your set up amd results thanks!
i bough a pair of 10.5 :1 cp forged pistons without knowing alot about compression ratios on turbo application and ive heard alot both good things and bad things and im a little bit conserned now to be honest, a friend told me to get bigger cams, i was running bc 272/272 he told me to run like 276's or 280's so the engine could "breath" better.. i dont know ..
I run 10.5:1 with 91 low quality gas on my 2g. You can run with 91 gas but at least you need to have a method and ability to adjust the ignition timing properly and should spray some w/m if you would exceed the stock boost level, otherwise you would be hearing knocks everywhere.
And just FYI, if the CP 10.5 pistons you mentioned is their off the shelf kit, then those would be around 10.0 on DSM. And the CR is calculated as using a 1.0mm thickness gasket. So if you use a popular MLS, such as cometic .051". the compression ratio would be around 9.8 on 85.00mm pistons. It would be around 9.5 with a 1.5-1.6mm thickness gasket.
 
I run 10.5:1 with 91 low quality gas on my 2g. You can run with 91 gas but at least you need to have a method and ability to adjust the ignition timing properly and should spray some w/m if you would exceed the stock boost level, otherwise you would be hearing knocks everywhere.
And just FYI, if the CP 10.5 pistons you mentioned is their off the shelf kit, then those would be around 10.0 on DSM. And the CR is calculated as using a 1.0mm thickness gasket. So if you use a popular MLS, such as cometic .051". the compression ratio would be around 9.8 on 85.00mm pistons. It would be around 9.5 with a 1.5-1.6mm thickness gasket.
I see.. i have a 70/63 turbo im not thinking on going past 15lbs of boost, also have adjustable sproker on it.. will it be "safe" ? To be honest i didnt take in consideration the type of fuel.. and would bigger cams help with 10.5 :1 comp? I currently have bc 272's
 
A "thick" HG will mess with the normal "Quench" area in the combustion chamber, so I would advise like the others did and find a set of lower compression pistons. I run 10:1 on my E85 motor and 9:1 on my 91 octane gas motor and really wish that motor was a 8.5:1 motor for more timing advance. That high of compression will limit you on timing, as already stated. I can only run 4*-5* without water meth but I will be running E85 on that motor also, and I can usually run more than 17* with E. Just an opinion.
 
I see.. i have a 70/63 turbo im not thinking on going past 15lbs of boost, also have adjustable sproker on it.. will it be "safe" ? To be honest i didnt take in consideration the type of fuel.. and would bigger cams help with 10.5 :1 comp? I currently have bc 272's

A turbo like that is wasted if you only use it for 15 psi (I assume you are referencing an eBay GT35R knockoff, which I wouldn't recommend). All of the lag of a big turbo without the power. Cams will tame it down a bit, but I would bet you start running into knock with your intended goals. It's just not worth it.
 
A turbo like that is wasted if you only use it for 15 psi (I assume you are referencing an eBay GT35R knockoff, which I wouldn't recommend). All of the lag of a big turbo without the power. Cams will tame it down a bit, but I would bet you start running into knock with your intended goals. It's just not worth it.
I see.. i understand and thanks for all the replies to all of you.. is just that my tunner told me high comp + low boost and that 70/63 will spool fast and have that poeer avaible fast , having forged internal would run with less stress and would be more reliable if ran with low boost .. so.. im guessing it all comes to the pistons i bought.. i think ill have to do some changes thanks you all
 
I see.. i understand and thanks for all the replies to all of you.. is just that my tunner told me high comp + low boost and that 70/63 will spool fast and have that poeer avaible fast , having forged internal would run with less stress and would be more reliable if ran with low boost .. so.. im guessing it all comes to the pistons i bought.. i think ill have to do some changes thanks you all

Your tuner is wrong. A high compression ratio makes more power off boost, but it doesn't speed up spool by any significant amount. The car will be much more fun with low compression, smaller turbo (FP 68HTA, FP Green or similar) and 23 psi on that forged bottom end. And it will be worry-free fun, since you don't have to worry about knock in any situation.
 
Your tuner is wrong. A high compression ratio makes more power off boost, but it doesn't speed up spool by any significant amount. The car will be much more fun with low compression, smaller turbo (FP 68HTA, FP Green or similar) and 23 psi on that forged bottom end. And it will be worry-free fun, since you don't have to worry about knock in any situation.
How could i make the best out of what i have? Or should i stock build the other 1g block i have sitting around..? Thanks for all your replies i shouldve done a little more research
 
A stock 6-bolt engine from a 1g can take a lot of abuse, it doesn't necessarily need to be forged. What is your power goal?
 
A stock 6-bolt can take that if it's in good condition and has a good tune. For 400 whp, I would go with the FP Green or HY35/HX35. Either should be pretty close to 400 whp at 23 psi or so, which should be safe on pump gas. Some cams like the GSC S2s would take away a bit of spool, but would make sure you hit your target HP goal.
 
As Cal said your off boost power will be great, so your daily driving and fuel economy out of boost will make you happy. I chose a higher compression for the off boost response, and I forgot the math equation but simply bumping up the compression it’ll make the same amount of power with I think 3-5 less PSI. With slightly better boost response and the ability to get better results on a smaller turbo before maxing it out is a pro.

In your shoes though I would go with a slightly lower compression since you don’t have that great of pump gas in your area.
 
As Cal said your off boost power will be great, so your daily driving and fuel economy out of boost will make you happy. I chose a higher compression for the off boost response, and I forgot the math equation but simply bumping up the compression it’ll make the same amount of power with I think 3-5 less PSI. With slightly better boost response and the ability to get better results on a smaller turbo before maxing it out is a pro.

In your shoes though I would go with a slightly lower compression since you don’t have that great of pump gas in your area.
Thanks for the advice i really apreciate all your comments
 
A stock 6-bolt can take that if it's in good condition and has a good tune. For 400 whp, I would go with the FP Green or HY35/HX35. Either should be pretty close to 400 whp at 23 psi or so, which should be safe on pump gas. Some cams like the GSC S2s would take away a bit of spool, but would make sure you hit your target HP goal.
Sounds like it could be a good option to install back the stock pistons and crank the boost at a safe zone.. looks like i have some work to do.. ill keep you guys update maybe upload a video when i finish the build
 
I see.. i have a 70/63 turbo im not thinking on going past 15lbs of boost, also have adjustable sproker on it.. will it be "safe" ? To be honest i didnt take in consideration the type of fuel.. and would bigger cams help with 10.5 :1 comp? I currently have bc 272's
Nobody can tell if it's safe or not without knowing your tuning ability but I would say no, it's not safe unless you know how to handle this kind of case. I am not talking about only that boost level is safe or not, I am talking with including every general thing to consider.
 
I would echo what others have said. Be honest with yourself with how you plan to drive the car. If you only plan on running 15 psi and you want a fun car that is plenty fast with good spool, stick with lower compression and a smaller turbo. These cars are very fun with a turbo that is operating in its efficiency range. I got that wrong with a couple setups early on.

What octane level do you normally run in Puerto Rico?
 
I would echo what others have said. Be honest with yourself with how you plan to drive the car. If you only plan on running 15 psi and you want a fun car that is plenty fast with good spool, stick with lower compression and a smaller turbo. These cars are very fun with a turbo that is operating in its efficiency range. I got that wrong with a couple setups early on.

What octane level do you normally run in Puerto Rico?
91, but its pretty easy to find other types of racing fuel
 
Well I have 8:5:1 pistons and will be running e85 on a long rod 2.0. Also forged internals with no squirters.Things you have to throw in thier are piston size, machine work ( like milling the head and block) and your head gasket and turbo size. Thier are alot of variables depending on parts used.
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