Higher compression 7AFE Options

[stephen_lee]

So I want to build my 7a with a little higher compresson (11-12:1) for a slight power increase and a nice increase in efficientcy and 'peppiness.' Upon searching I found little to no information about where I can get a set of high CR pistons w/o having to mod the rods and whatnot. So does anyone know who, if anyone. caries a higher CR piston for the 7a? If not, where i can get a good set of customs from? This is on a spare 7a so no big deal if i have to wait/ship my stock pistons. And does anyone know about rod bolts? I know thats one of the 7a's weak spots so if ARP has any bolts to fit that'd be great, or if anyone knows of some stronger bolts... I like to beat my engines so it'll have to be strong enough to handle my habits.

shorthand:
1.) Where can i get higher CR pistons for the 7a? (11-12:1)
2.) How can I beef up my rods/rod bolts?
3.) Don't flame about my building choices, I went this way for a reason.

[nik]

one question why not swap a 20v silver or black top in?

[stephen_lee]

7a has more torque at lower RPM, and better economy.
This 7a is going in my daily, so I want the nice low RPM torque and the 30ish MPG.

4age's do not have those qualities.
For my power celi my GT will have a 3s soon

[nik]

7a has more torque at lower RPM, and better economy.
This 7a is going in my daily, so I want the nice low RPM torque and the 30ish MPG.

4age's do not have those qualities.
For my power celi my GT will have a 3s soon

well when you bump your compression up your mpg will go down plus youll have to run higher octane gas to aviod knock

not on 100% on this but could do a couple things buy 4ag high comp pistons also maybe deck the block and or shave it. To up the comp

imo if you want to keep the mpg i wouldnt really do anything to up besides maybe a p&p and clean it up

[stephen_lee]

I thought a higher CR increases mpg due to better burn efficiency, it pulls in the same amount of fuel/air doesn't it? plus I use supreme anyhow, its cleaner around here

[RavenAegis45]

I thought a higher CR increases mpg due to better burn efficiency, it pulls in the same amount of fuel/air doesn't it? plus I use supreme anyhow, its cleaner around here

Well in a way yes but its not that simple. Increasing Comp on an engine designed with a lower comp still using the same Fuel system to inject the fuel will hurt MPG because its not deigned for such High Comp and the fuel and Air mixture will be sucked in at the regular compressions rate. Also even though your going to be using higher octane than needed usng the stock ECU settings will most likely cause knocking sine older cars knock sensors aren't that great. Plus your shooting a little highfor what you want. I suggest a little over 10.0 to 1, (11-12 is really high)

[zoik]

http://atomicspeedware.com/search.aspx?fin...amp;category=36
check this , arias has done some piston with high cr

[Bitter]

a .5 bump in CR won't even really be noticable. 11-12:1 is getting up there. 9.5:1 is stock. you can't just bump CR without other changes, the cams are ground to work with stock CR and the cam timing is set that was as well. you'd need different ground cams as well as adjustable cam gears to take full advantage of it.

my advice and the cheapest way to add a little 'pep' to the 7afe is...set timing to 13-15 BTDC and throw a wrapped ebay header on it along with a cold air intake. no earth shattering gains but its something you'll feel in the seat of your pants and way cheaper to do. also shouldnt hurt mpg any and you can get away with midgrade fuel.