high compression

[15 sec gs]

i was searching around the site and im not really finding what im looking for. I was wondering how high compression i can run safely on stock fuel maybe upgraded injectors. will i be fine at 11:1, and where would i be able to find half decently priced pistons.


thanks in advance
mike

 

[talon4lifetsi]

I've dealed with them for year and look at there package deals.

extremepsi.com

 

[15 sec gs]

the highest i can find on there is 9.0:1 i kinda wanted something a little higher

 

[c4uldr0n]

11:1 on a non turbo with 93 octane would probably still ping a little, I'd be concerned unless you had something to monitor you knock and or a tuning device to alter your timing a little.

 

[15 sec gs]

whats the highest i could go with no worries?

 

[c4uldr0n]

It can seriously vary from car to car. What are your goals with the car? Do you want higher compression for more HP, better low rpm torque, is it a race car? Give us a little background and maybe we can better assist you.

 

[15 sec gs]

well everyone turbos there car and i just want to make a sick nasty non turbo, i do race the car alot, i would like to make high hp and i was told this is the way to do it...correct me if i am wrong

 

[TSITuner4Lyfe69]

n/a is not the way to go Turbo is and you dont wanna turbo a high compression motor its pointless without rods and built motor kinda like a honda WORTHLESS

 

[c4uldr0n]

You can make a fast n/a, and you can also make a fast turbo. Ultimately you can make more power with a turbo. I'd say if you want to pick up 20whp, you can do it with your n/a with intake, exhaust, cams. If you want 50+whp, I'd say go turbo. N/A can also be very expensive, just as much as high horsepower turbo.

-c4

 

[TunaTalon]

i was searching around the site and im not really finding what im looking for. I was wondering how high compression i can run safely on stock fuel maybe upgraded injectors. will i be fine at 11:1, and where would i be able to find half decently priced pistons.


thanks in advance
mike

You’re asking a simple question about a complex process. An engine’s tolerance to higher compression ratios depends on several factors such as ignition timing, fuel octane, fuel/air ratio, intake temperature, combustion chamber shape, and piston shape.
If you go outside of the normal and tested box you will be on your own.

If you have the skills of the Corvette design team you may be able to approach the 10.9:1 compression ratio available for the new ZO6. The phrase “don’t try this at home” comes to mind here.

To learn more about the combustion process I can recommend subject 7 of http://www.jcmmachine.com/PDF files/JCM Tech Report ch 4 to 9.pdf.

In that article you will find:
For a typical carbureted engine, without engine management.

Compression Octane Number Brake Thermal Efficiency
Ratio Requirement ( Full Throttle )
5:1 72 -
6:1 81 25 %
7:1 87 28 %
8:1 92 30 %
9:1 96 32 %
10:1 100 33 %
11:1 104 34 %
12:1 108 35 %

 

[talon4lifetsi]

You could build the motor with alittle less compression and take the easy way out and throw some nitrious on it. Alot easier that way also.

 

[15 sec gs]

isnt nitrous really really bad for your motor dont forget this is my dd

 

[c4uldr0n]

And you want high compression pistons on your DD?

I'd say do this:

1. Make a budget
2. Create a timeframe
3. Set a hp/tq goal

-c4

 

[JayRolla]

The fastest N/T 2g is only laying down 175whp and that is with a lot of money and modding. In my opinion your going to spend so much money you could buy a turboed dsm and be done with it.

 

[15 sec gs]

yeah i kinda see where you guys are coming from i thought i would be able to put out alot more horse power with a non turbo but i guess not i guess ill have to get my shit in gear on 80 days untill the high school challenge at maple grove