Stock Compression Ratio
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Melting Slicks
Joined: Sep 2002
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From: Union City CA
Stock Compression Ratio
What is the combustion camber CC rated at for a stock 84 corvette head? I'd like to change the heads now so I can take some advantage of extra $$, I will use these heads later on for when I drop compression for forced induction, but right now I'd like to know what is the combustion chamber Displacement so I dont run too high of a compression Ratio when I put them in. Thanks for replys :flag
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From: Framingham MA
Re: Stock Compression Ratio (Light84vette)
76cc is correct they were used on 78 - early 86 corvette. I wouldn't used these head for performance build up, they are thin so they can't be ported too much and are prone to cracking. Iron heads are also more liking to detonate, not a good choice for a SC.
If you keep the compression reasonable 9.0-9.5:1 you can run 10-12 psi of boost if your lower end is upto it.
If you keep the compression reasonable 9.0-9.5:1 you can run 10-12 psi of boost if your lower end is upto it.
Thread Starter
Melting Slicks
Joined: Sep 2002
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From: Union City CA
Re: Stock Compression Ratio (dgoodhue)
If I use an Iron head, and I out an intake-Arir Gap and put on two 670CFM 2bbl TB INjectors which support only 225HP each, will that increase my HP to at least 300HP? LIke a High FLow intake, headers, and high flow heads? Say stock compression b/c I'll change rotating assembly later on before I get the turbos on. BTW which head manufacturer would you suggest makes a high flow Iron head that is still somewhat smog legall? WHat is the main diff between a smog head and a none smog head?? :confused:
Also do you guys think an Aluminum head works better with turbo applicatuons or does iron heads work better? I will be using a 383CID 8.5 to 1 compression forged everything, and I plan on making 700ish HP FLY, any suggestions on heads and intake----High Flow ones :confused: ;)
Also do you guys think an Aluminum head works better with turbo applicatuons or does iron heads work better? I will be using a 383CID 8.5 to 1 compression forged everything, and I plan on making 700ish HP FLY, any suggestions on heads and intake----High Flow ones :confused: ;)
Melting Slicks
Joined: Jan 2002
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From: Atlanta GA
Re: Stock Compression Ratio (Light84vette)
aluminum ia always better... If your doing that much work... better get yourself some nice AFRs or something nice like it.... The problem with iron is they retain heat.... turbos create heat..... put them together and you can't nearly the same amount of boost because heat creates detonation... and thats bad.... Run like 8.5:1 alumunum heads, and a bottom end thatt can take the power and go from there
Thread Starter
Melting Slicks
Joined: Sep 2002
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From: Union City CA
Re: Stock Compression Ratio (StealDads67)
Thanks for that, I got all mixed up with the aluminum and iron head problems. I was told that iron heads make more power because they retain heat, but I can see why a Forced induction engine would need an aluminum head setup because there already packing a lot of heat so if they loose some it wont hurt.
Another thing wherecould I get some AFR's and how much do they go for? HOw many lbs can I Lose with them? ;)
Another thing wherecould I get some AFR's and how much do they go for? HOw many lbs can I Lose with them? ;)
Melting Slicks
Joined: Jan 2002
Posts: 2,784
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From: Atlanta GA
Re: Stock Compression Ratio (Light84vette)
Im guessing you could lose a solid 30lbs with them...... they are little pricey but are a great head... They can be had at about $1200 depending on what kind you get (ex. 190, 195, 210..... )
Check out there website... http://www.airflowresearch.com/
I love the homepage... the background music gets me in to mood to spend money and make my car faster hahaha
Check out there website... http://www.airflowresearch.com/
I love the homepage... the background music gets me in to mood to spend money and make my car faster hahaha
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Thread Starter
Melting Slicks
Joined: Sep 2002
Posts: 2,631
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From: Union City CA
Re: Stock Compression Ratio (StealDads67)
Yeah the music does kinda sound like that :lol: BUt anyway the heads are a bit pricely. but I did find some 195cc heads aluminum that flow 195cc, thats enough for me, but I cannot find any 76cc combustion chamber heads, aluminum that is. BTW I heard that aluminum heads dont make too much power as do Iron ones when you run NA. THis must be the other way around when you run with forced induction or am I mixed up? ;) :auto:
Melting Slicks
Joined: Jan 2002
Posts: 2,784
Likes: 3
From: Atlanta GA
Re: Stock Compression Ratio (Light84vette)
I have never heard of that.... I dont think that is true.... but I could be wrong..... I am inclined to think you will make better power with aluminum because your running cooler air... But if there is a difference I think it would be negligable.
...... If your going to take to motor out and build it up, you dont need the 76cc... Thats really big anyways... Find the pistions that you want and see what CC give you what compression and make a combo from that.....
...... If your going to take to motor out and build it up, you dont need the 76cc... Thats really big anyways... Find the pistions that you want and see what CC give you what compression and make a combo from that.....
Thread Starter
Melting Slicks
Joined: Sep 2002
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From: Union City CA
Re: Stock Compression Ratio (StealDads67)
If I use aluminum heads, 195cc and run 9.5 to 1 compression 350CID, 2.055 intake valve and 1.6 exhaust valve with the right amount of fuel delivered from a pair of 2bbl TB injectors which can support 450HP, HOw much could I see? Say if I use RPM edelbrock intake and some good size flow headers? :confused: is 375HP out of the question?
Melting Slicks
Joined: Jan 2002
Posts: 2,784
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From: Atlanta GA
Re: Stock Compression Ratio (Light84vette)
I would say go with a lower compression.. somewhere like 8.5:1.... your talkin Forced Induction correct? Are you turbo or superchargering?
You didnt say anything in your last post about that.... If your going N/A then you want high compression... 11:1 is suffiecent and still good on pump gas (with aluminum heads)
It also depend on the kind of cam you are running... Your going to have to deside what you are going to do there.... You have alot of planning to do. you have to know what you want to do first
You didnt say anything in your last post about that.... If your going N/A then you want high compression... 11:1 is suffiecent and still good on pump gas (with aluminum heads)
It also depend on the kind of cam you are running... Your going to have to deside what you are going to do there.... You have alot of planning to do. you have to know what you want to do first
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Joined: Dec 2002
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From: Charleston SC
Re: Stock Compression Ratio (Light84vette)
The 84 came with cast # 624 heads 76cc and their is no way I would use these heads on a High compresion or forced air Motor they are relitivly thin heads and are comonly cracked even with just normal operation with high milage due to the fact the 84 was desinged to run so hot from the factory.
Thread Starter
Melting Slicks
Joined: Sep 2002
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From: Union City CA
Re: Stock Compression Ratio (StealDads67)
I'm just going to do a Head and intake and TB injector swap for now for a little fun, my car gets capped on all the time b/c many other cars are faster then it. So I will use these heads and intake, but when it comes time to go for Turbos I'll changed the pistons for some dished out pistons, rods and 3.75 crank and all forged, oh did I mention I'll bore it as well to 383CID. When I do this I will lower the compression from 9.5 to 8.5 with the pistons, I just want to now what kind of power can I see with this swap---Aluminum Heads, specs listed above and air gap intake and 2 2bbl TB INjectors---450hp capacity of them both put together. So what do you guys think?
Oh and I'm ditching my HEads, thats what the whole topic is practically about, I dont know where you got misinformed about me keeping my stock heads, no never I;m ready to toss them in the garbage :yesnod: :yesnod:
Oh and I'm ditching my HEads, thats what the whole topic is practically about, I dont know where you got misinformed about me keeping my stock heads, no never I;m ready to toss them in the garbage :yesnod: :yesnod:
Melting Slicks
Joined: Jan 2002
Posts: 2,784
Likes: 3
From: Atlanta GA
Re: Stock Compression Ratio (Light84vette)
Well... no you did not mention it but I just figured that from when you said you were putting in the 3.75 stroke crank ;) You dont bore your way to the 383... its mostly the crank.... 383 is .030 overbore (4.030) and 3.75 crank
the bore only gives you 5 cubes
Anyways... All the power is in the Heads Cam and intake.... 450 would not happen with jus tthat... You need a cam if you want anything NEAR that power!.... and its still a high number to shoot for with the stock bottom end. I dont know what kinda numbers that intake set-up is good for, or what range its works in.... Your gonna have to figure that out....
Then your going to have to do headers and exhaust and change the fuel pump and a lot of other little things that add up, dont forget about these....
the bore only gives you 5 cubes
Anyways... All the power is in the Heads Cam and intake.... 450 would not happen with jus tthat... You need a cam if you want anything NEAR that power!.... and its still a high number to shoot for with the stock bottom end. I dont know what kinda numbers that intake set-up is good for, or what range its works in.... Your gonna have to figure that out....
Then your going to have to do headers and exhaust and change the fuel pump and a lot of other little things that add up, dont forget about these....
Thread Starter
Melting Slicks
Joined: Sep 2002
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From: Union City CA
Re: Stock Compression Ratio (StealDads67)
I think you misread my post but its okay, anyway I said the TBI have a capacity of 450HP, I only plan on making 350+HP from this setup, I will use a HIgh Flow intake and then fabricate a lid which will be feed by two 2bbl TBI's. So I was saying if I run a 350CID just for now with 9.5 to 1 compression with aluminum heads, yet again the specs are posted above and some high flow headers.
I just want to know if I could reach the 350HP mark or not with this. The 2bbl TBI's act like carbs so I think the intake and fuel delivery system should be pretty good for power numbers.
Also Will my stock drivetrain last for say 2-3months with this setup. Maybe 360HP and 380FtLBs of tq? OR will it all break up?
I just want to know if I could reach the 350HP mark or not with this. The 2bbl TBI's act like carbs so I think the intake and fuel delivery system should be pretty good for power numbers.
Also Will my stock drivetrain last for say 2-3months with this setup. Maybe 360HP and 380FtLBs of tq? OR will it all break up?
