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Stock 289 horsepower and rpm???

my68cs

Active member
Joined
Aug 5, 2006
Messages
28
Location
Eastern Oregon
I was just wondering how much horsepower a stock 289 with a 2bbl would have? My car now has headers with Flowmaster Supers 40s and true dual exhaust. And also, what's the highest rpm you could go without backing it off?
 

robert campbell

Well-known member
Joined
Apr 10, 2007
Messages
4,321
The 2 barrel 289 was rated at 200 horsepower at the flywheel. The 4 barrel 289 was rated at 225 at the flywheel.

Max RPM would be 5,000 to 5,500. The stock cam really stops giving any more power at 5,000 rpm. The stock hydraulic lifters will "float" at anything above 5,500 and you could risk valve to piston contact. Very dangerous!

I would not rev it past 5,000 myself. Risks breakage and would not really go any faster.

Sounds like you have got the exhaust side opened up. Want any suggestions on your next steps to go faster? Are they long tube full length headers? I have built many a small block.

Rob
 

rvrtrash

Well-known member
Joined
Apr 25, 2003
Messages
3,649
If I had to guess, I'd say it would be around 190-200 horse at the flywheel. As for RPM, I believe with a stock engine, you'd start to get valve float at about 5500-6000 rpm, but if it's getting a little tired that might be lower. Just my guesses of course.

Steve
 
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M

my68cs

Active member
Joined
Aug 5, 2006
Messages
28
Location
Eastern Oregon
The 2 barrel 289 was rated at 200 horsepower at the flywheel. The 4 barrel 289 was rated at 225 at the flywheel.

Max RPM would be 5,000 to 5,500. The stock cam really stops giving any more power at 5,000 rpm. The stock hydraulic lifters will "float" at anything above 5,500 and you could risk valve to piston contact. Very dangerous!

I would not rev it past 5,000 myself. Risks breakage and would not really go any faster.

Sounds like you have got the exhaust side opened up. Want any suggestions on your next steps to go faster? Are they long tube full length headers? I have built many a small block.

Rob




Exactly what are long tube full length headers?? And no I don't need any suggestions on how to go faster. I can get into enough trouble as it is. Thanks though!!
 

robert campbell

Well-known member
Joined
Apr 10, 2007
Messages
4,321
Typically long tube headers are tubes about 36 inches in length that extend down to the lower chassis and go into a "collecter" 3 inches in diameter. Each header tube is about the same length.

A shorty header is similar but the tubes are less than 24 inches in length and exit about mid engine and close to the firewall.

Rob
 
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my68cs

Active member
Joined
Aug 5, 2006
Messages
28
Location
Eastern Oregon
Typically long tube headers are tubes about 36 inches in length that extend down to the lower chassis and go into a "collecter" 3 inches in diameter. Each header tube is about the same length.

A shorty header is similar but the tubes are less than 24 inches in length and exit about mid engine and close to the firewall.

Rob

They are short headers. Why is that?? I know headers up the hp but I don't know how much. I know too that the exhaust is 2.5". I don't know if that would make a difference or not.
 

robert campbell

Well-known member
Joined
Apr 10, 2007
Messages
4,321
Short headers are a big step up from stock cast iron manifolds. They are called shorty’s. I have a set of JBA shorty’s on my GT/CS. The secret to big power is long tube (equal length) headers. They do make equal length shorty headers for newer Mustangs (1979 up) but to my knowledge not older Mustangs.

Long tubes with longer collectors have been tested against shorty’s and cast iron and they do make the best power in any motor. Combination of better scavenging and so on. At the same time all of this power comes at high RPM’s. 4.500 and up. In a mild build a shorty set will make as much low end and not much less high-end power.

You have great start and shorty’s fit better and do not create ground clearance problems that long tubes do. And if you have power steering they shorty’s do not need to drop the chassis mount point for the power ram. The best of all worlds in a mild build.

Next step for you is better heads, (lots of options) and a 4-barrel and a cam!!! The edelbrock RPM package is a great choice!!! I love to spend other peoples money!!! Do you want to stomp those Chevy’s??? See the 347 stroker thread that Paul Newitt started. Lots of good ideas that will work with a 289 or 302!!

Rob
 
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