This is topic can I run 10.5:1 compression??????? in forum Tech Talk at Northern California Ford Owners  .


To visit this topic, use this URL:
https://californiafords.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=6;t=003116

---

Posted by 19falcon66 (Member # 2433) on :
 
Hey I was wondering if I can run 10.5:1 compression and still use pump gas not realy shure what to think I was told i could but I thought I would ask around and see hat other people think.

"Wonder if heavens got a ghetto and a drag strip"
 

---

Posted by 93mustangt (Member # 680) on :
 
Yes you can but you need aluminum heads.
 

---

Posted by 4.6 EATIN GM'S (Member # 1633) on :
 
why would u need aluminum heads i had 11.1 on a old chevy set up with iron heads
and yes u could run 10.5:1 on pump gas i have 10.5:1 on my new motor and im going to run 91 octane for it
just dont plan on supercharging it
 

---

Posted by 19falcon66 (Member # 2433) on :
 
i'm not going to supercharge it i am going to be runnong li ke 150 shot of nitrous and i will be using aluminum heads since it will be cheaper since i got a brand new short block.
 

---

Posted by 4.6 EATIN GM'S (Member # 1633) on :
 
u shouldnt have no problems then
 

---

Posted by 93mustangt (Member # 680) on :
 
Oh i thought that with that compression you would have to run aluminum heads i guess not.So if i were to rebuild my motor i could run 10.5/1 without any worry of it pinging?Would i still be able to run the same timing?
 

---

Posted by SIR Paint Job w/ '84 TercelOnYoMama (Member # 1708) on :
 
if your car has computer controled timing then you can run a bit more compression than you can with a mechanical dist.
 

---

Posted by 93PONY (Member # 60) on :
 
IMO it really depends on the cam.

You can build a 11 to 1 compression motor that runs on pump gas if the cam is small enough. & you run into detonation on 9.5 to 1 motors with a good cam...

Compression ratio means very little. Cylinder pressure is what matters.
 

---

Posted by st5150 (Member # 51) on :
 

quote:

---

Originally posted by 93mustangt:
Oh i thought that with that compression you would have to run aluminum heads i guess not.So if i were to rebuild my motor i could run 10.5/1 without any worry of it pinging?Would i still be able to run the same timing?

---

quote:

---

Originally posted by st5150:

quote:

---

Originally posted by 93mustangt:
Oh i thought that with that compression you would have to run aluminum heads i guess not.So if i were to rebuild my motor i could run 10.5/1 without any worry of it pinging?Would i still be able to run the same timing?

---

Aluminum heads "effectively" lower the compression ratio by drawing heat away from the combustion chamber. For example, a 8.8:1 iron headed motor would "act" like a 8.0:1 motor if the iron heads were replaced with identical aluminum castings.

93PONY- can you spec me a cam to fix my leaky power steering rack? Its getting kinda annoying.

---

Actually, Aluminum heads disipate heat faster & allow you to run more cylinder pressure on a given octane....it does not lower your compression....

No cam for you!
 

---

Posted by st5150 (Member # 51) on :
 
Which is why I said ""effectively"" and ""act"" in my post. Read what I wrote again and let me know if I wasn't clear on something because once again you just said what I said, but in a different way
 

---

Posted by 93PONY (Member # 60) on :
 
Nah. It's all about cylinder pressure....not compression. 2 different things....related, but no the same.

However in this instance, we are both saying you can run more.....cylinder pressure with aluminum heads given the same octane.
 

---

Posted by st5150 (Member # 51) on :
 
I never said cyl pressure and compression were the same thing


 

---

Posted by 91sleeper (Member # 779) on :
 
You guys are like two little kids fighting for who gets the credit.
 

---

Posted by st5150 (Member # 51) on :
 
Obviously the guy who has a twin turbo cobra won the credit card fight and not the guy with the stock LX
 

---

Posted by 93PONY (Member # 60) on :
 

quote:

---

Originally posted by st5150:
Obviously the guy who has a twin turbo cobra won the credit card fight and not the guy with the stock LX

---

That guy always wins.... Although he doesn't have any parts on the credit card.
 

---

Posted by mustanggt5091 (Member # 444) on :
 
You shouldnt have any problems. I run 11.1:1 compression on my car ( with aluminum heads ) and can still run 89 octane without knocking and pinging. I run a fuel injected motor so It may be a little different. I can tell you my brothers chevy 400 has 10.25:1 compression and runs fine with 91!
 

---