300 CR/piston question
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Postmaster
Joined: Mar 2005
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From: Earth
300 CR/piston question
What's the stock CR for a 1986 300? And what's a good target CR if you were going to rebuild?
Also, will 4.03 bore pistons from a 302 or 351 work in a 300? I swear I've seen a SBF stroker motor built with 300 rods, could you use stroker 302/351 rods in a 300?
Also, will 4.03 bore pistons from a 302 or 351 work in a 300? I swear I've seen a SBF stroker motor built with 300 rods, could you use stroker 302/351 rods in a 300?
Postmaster
Joined: Jul 2003
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From: Pittsburgh
Yeah, but using 390 pistons requires a minimum .050 overbore.
You can use chevy 327 pistons if you get your connecting rods rebushed down to the GM pin diameter and that REALLY opens up your piston choices.
On a stock or stockish 300 I like 9.0-9.5:1. It's a nice number to run on regualr or midgrade fuel for a daily driver and it does help out a little in power, plus you can get the pistons off the shelf at Autozone or Oreilly's.
When I rebuilt my 300 I ran 9.0:1 and a 262 duration cam and it really woke it up even though i was still running the stock 1bbl and single exhaust.
Justin
You can use chevy 327 pistons if you get your connecting rods rebushed down to the GM pin diameter and that REALLY opens up your piston choices.
On a stock or stockish 300 I like 9.0-9.5:1. It's a nice number to run on regualr or midgrade fuel for a daily driver and it does help out a little in power, plus you can get the pistons off the shelf at Autozone or Oreilly's.
When I rebuilt my 300 I ran 9.0:1 and a 262 duration cam and it really woke it up even though i was still running the stock 1bbl and single exhaust.
Justin
Elder User
Joined: Nov 2005
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i have to agree with hoxii, while i can't give a specific number, if you go up much higher than maybe 9.5 or 10 then you run into problems with not being able to run anything but premium, if you can even get away with that, you dont want excessive pinging ruining your premium built engine
Postmaster
Joined: May 2002
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From: Broken Arrow, OK
Adding compression is almost as futile as adding displacement for power production, but it will help mileage and throttle response. There are probably a dozen or more 300 pistons out there with dishes anywhere from 0 cc up to around 35 cc. That gives you about 2 compression points to play with. I would look into something like that before I got too creative with random parts. You should be able to get into the 9.5-10:1 range without going to a piston from a different engine.
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Tuned
Joined: Oct 2004
Posts: 288
Likes: 7
From: Denver, Co
Hey silver
How do you figgure add compression dosen't add power?
And where are you finding these great 300 pistons?
Are they forged?
Have you ever priced a set of forged 300 pistons?
Ferrarri prices for 6-banger slugs
How do you figgure add compression dosen't add power?
And where are you finding these great 300 pistons?
Are they forged?
Have you ever priced a set of forged 300 pistons?
Ferrarri prices for 6-banger slugs
Last edited by HunterSThompson; Apr 9, 2007 at 06:26 PM.
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Postmaster
Joined: May 2002
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From: Broken Arrow, OK
I didn't say it wouldn't add more power, I said it was futile. There's no sense spending a bunch of money adding compression because you won't get your money's worth out of the effort. If you spent $400 to add 2 points of compression you might get a whole 10-15 hp out of it. Big deal. You could spend that same $400 on improving the breathing and get 3 times as much improvement. Just use the off the shelf piston that gets you closest to the desired ratio and live with it.
Where did I find pistons? Silvolite offers 11 different part numbers, including 6 hypereutectics.
http://kb-silvolite.com/spistons.php...=Ford&Div=Ford
Where the hell did forged come from? The word forged didn't appear anywhere in this thread until you pulled it out of the clear blue sky. If you are building enough of a 300 to legitimately need forged pistons you shouldn't be crying about the price of a set of custom pistons. The cost of a set of pistons will be a drop in the well. FWIW, yes I have priced them. They were about $450/set two years ago. That doesn't sound all that bad to me, especially considering you would have 10 times that much in an engine that needed them.
Where did I find pistons? Silvolite offers 11 different part numbers, including 6 hypereutectics.
http://kb-silvolite.com/spistons.php...=Ford&Div=Ford
Where the hell did forged come from? The word forged didn't appear anywhere in this thread until you pulled it out of the clear blue sky. If you are building enough of a 300 to legitimately need forged pistons you shouldn't be crying about the price of a set of custom pistons. The cost of a set of pistons will be a drop in the well. FWIW, yes I have priced them. They were about $450/set two years ago. That doesn't sound all that bad to me, especially considering you would have 10 times that much in an engine that needed them.
Elder User
Joined: Nov 2005
Posts: 733
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i'd have to agree, the only person i heard of blowing a hyper piston in a 300 was playing with over 20psi boost with a turbo and already high compression. forged looks cool on a spec sheet, but 99.99% of engines don't need them, they're expensive because there is not that big of a market for them. and if you're putting forged pistons in a 300, odds are you already uprgraded the con rods, so you could use any 4.000 diamater piston you wanted...
and have you ever priced ferarri pistons?
and have you ever priced ferarri pistons?
Tuned
Joined: Oct 2004
Posts: 288
Likes: 7
From: Denver, Co
dammmm sorry to ruffle your feathers guys
I just asked about these neat pistons Silver is so fond of - then asked if they were forged - then asked if he had priced forged pistons - where do you get off on that tirade?
I'm not the one wanting a 400 horse 6 popper.
Yes
I just asked about these neat pistons Silver is so fond of - then asked if they were forged - then asked if he had priced forged pistons - where do you get off on that tirade?
I'm not the one wanting a 400 horse 6 popper.
Originally Posted by NavyMIDN08
and have you ever priced ferarri pistons?
Last edited by HunterSThompson; Apr 10, 2007 at 12:01 AM.
Post Fiend
Joined: Jan 2004
Posts: 5,377
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From: Elkhart IN
Theres alot to play with dialing in a cr with decking the block and the head, along with thicker and thinner head gaskets of course. And of cours if your running a wild cam, that will have alot to do with your figured c/r and your actual c/r.
Tuned
Joined: Oct 2004
Posts: 288
Likes: 7
From: Denver, Co
uhhhhhh,
more compression on old rings - with the additional; dirt and debris likely to find it's way into the motor during the change a betting man might wager on,,,, any gains will be short lived.
And - port size could be smaller with the 240. That would be a noticable limit on the top end.
easiest gain would be to mill the original head - it's already paid for - but if the bottom end isn't tight and right - rings and bearings - it will be like shifting gears on a hand grenade - sooner or later,,, BOOM, tinkle, tinkle.
If it ain't broke,,,,
more compression on old rings - with the additional; dirt and debris likely to find it's way into the motor during the change a betting man might wager on,,,, any gains will be short lived.
And - port size could be smaller with the 240. That would be a noticable limit on the top end.
easiest gain would be to mill the original head - it's already paid for - but if the bottom end isn't tight and right - rings and bearings - it will be like shifting gears on a hand grenade - sooner or later,,, BOOM, tinkle, tinkle.
If it ain't broke,,,,
Last edited by HunterSThompson; Apr 10, 2007 at 07:10 PM.
Putting a 240 head on a 300 IIRC will give you somewhere in the neighborhood of 9.5 to 10.0/1 comp.