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1971chev 02-02-2013 07:40 AM

327
 
I just dynoed my 327 and came out with 300 rwhp and 360 ftlbs with 6 pounds of boost through a weiand 177. The motor is bored 30 over 9-1 compression ported double hump 64 cc heads, comp 292 h cam and ram horm manifolds. My question is why does the 300 seem low for this motor.

snakebit68 02-02-2013 08:12 AM

blower
 
What RPM did your peak HP come in at? Keep in mind that you'll lose 20-30% of you power in the drivetrain. Which means your engine with the blower is producing closer to 400 HP at the crank. Which isn't really too bad. Those smaller blowers aren't known for making any substantial hp gains. I think they're fun and look cool as heck, but for the money just dont provide enough bang for the buck. Have you ever been to the drag strip? If you go, take a walk through the pits and check out some of the cars...you wont find many with blowers on them. I've been racing for years and have only seen a handful of cars with them. But they certainly look and sound cool. I wouldn't be too disappointed with 300 hp out the back end of the car. Maybe a little fine tuning and larger jets could improve those numbers

1971chev 02-02-2013 08:17 AM

peaked at about 5800. The tuner said the cam has too much overlap and the ram horns are killing it. He was thinking it should have done 350 plus at the wheel. Im sure the 3.08 gears aren't helping.

vinniekq2 02-02-2013 08:27 AM

gears do not effect the horse power at all. The exhaust is the most important part to make power.The cam is actually a little small.May want to change to a blower friendly cam,1 3/4 inch primary headers and 3 inch or bigger mandrel bent exhaust.That should net 60 plus horses

snakebit68 02-02-2013 08:44 AM

blower
 
Yes, there are cams out there specifically designed to be run with a blower. Usually with far less overlap

cdminter59 02-02-2013 08:46 AM

327
 
Back in the day there was a 327/300 but that was at the flywheel. The engine needs some help breathing. A set of 1 5/8 full length headers and a free flowing 2 1/2 dual exhaust would help. Your compression is too low for that camshaft also. That camshaft needs 11.5:1 compression and a 200ccc set of heads. Your heads would be lucky to be 165cc. I don't see how you got 300 hp with the parts you rebuilt with.

snakebit68 02-02-2013 08:52 AM

heads
 
thats true...your engine needs to breathe and a good set of headers would net you the best gain for your money. But investing in a good flowing set of heads will really boost your hp and torque. You can do the headers without changing the heads...but you cant change the heads without changing the headers. All the flow in the world will do you no good if you cant move it through the exhaust

F-BIRD'88 02-02-2013 01:12 PM

What was the blower drive ratio?

More power: tube headers
More power Cam Crane F278-2. use good springs.

With a 9:1cr you will need a better high octane fuel to kick up the boost
but if when you do that, it will make a lot more power.

This blower is capable of high power.

You did well for what you go and a first effort. There is a lot more in it.

Again what was the blower drive ratio and indicated boost?

Note: chassis dynos can be very humbling. Especially depending on how they are calibrated and the setup.
Use for comparision to find more power by changing parts and tune. Not absolute numbers.
( it shows you what makes more power.)

1971chev 02-02-2013 01:46 PM

The boost was 6 pounds with stock pulleys, i think its 3.48 upper pulley.

F-BIRD'88 02-02-2013 02:00 PM

Quote:

Originally Posted by 1971chev (Post 1641803)
The boost was 6 pounds with stock pulleys, i think its 3.48 upper pulley.

You got lots of room to grow. The boost was a bit false high because of the exhaust. The engine cannot get rid of the exhaust so boost climbs and power gets choked off.

@9:1 cr you will need high octane gas to step on it much harder (boost)

Get some 110 for testing 2.10 to 2.33:1 drive ratio
Ditch the cam and the ram hornes.
Heads may be restrictive. The boost is higher than I would expect
( boost is a back pressure reading of what is not getting into the motor.
It cannot get in if it cannot get out.

Again use the chassis dyno to find power by tuning. Then run it down the drag strip.
MPH='s power

A 7.5:1 cr allows a lot more boost on pump gas. The 9:1 cr is going to limit it on pump gas.
Crane F278-2
Crane F280-2
www.cranecams.com
you are off to a good start.

Flow test on your "ported" heads. They may have a bad exhaust port. but headers first.

With a MPH from a few drag strip time slips you can quantify what the "300hp" chassis dyno number means.
Right now it is just a number. and highly variable. Lots of factors.
The point and only point of these dynos is to find 301 hp... 302 hp.... 325hp..... thru tuning.


Carb??? ignition timing?
On a chassis dyno the car's gear ratio and torque converter and tires are a huge factor. and more....
again a chassis dyno is for FINDING MORE POWER.

1971chev 02-02-2013 02:08 PM

Thank you for the input i am definatley looking in to the cam and headers for it.

Hogg 02-02-2013 02:10 PM

Quote:

Originally Posted by cdminter59 (Post 1641687)
Back in the day there was a 327/300 but that was at the flywheel. The engine needs some help breathing. A set of 1 5/8 full length headers and a free flowing 2 1/2 dual exhaust would help. Your compression is too low for that camshaft also. That camshaft needs 11.5:1 compression and a 200ccc set of heads. Your heads would be lucky to be 165cc. I don't see how you got 300 hp with the parts you rebuilt with.

You realize it has a supercharger on top, right?

F bird has some good advice.

peace
Hog

1971chev 02-04-2013 07:23 AM

Carb is a 650 holley air fuel is at 12.5 and timing is 31 all in at 2500 rpm

vinniekq2 02-04-2013 07:34 AM

650 is small,but will work. all seems in order still.get some exhaust under the car(I reiterate)

Waksabi 02-04-2013 10:09 AM

too much cam.


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