New 427 Dyno Numbers : Learn from my mistakes!

[Shelbytexas]

I hope many will find this info and interesting - this is a follow -up to that previously posted. At issue was the 454 (427 with 3.98 crank) that produced only 301 Hp and 385 ft-lbs of torque.

Engine: '65 Center-Oiler with 3.98 Crank
Edelbrock Alum heads
2.19 / 1.75 valves
Police intersecptor alum. intake
DaVinci 850 Carb
Harlan Sharp Roller Rockers
2.5 inch exhaust
Flowmaster mufflers
timing: 10 degrees initial, 36 d total
Cam: Comp Cams Extreme Energy Hydrolic: .565 lift / 230 d dur @ .050
Car is a '68 Shelby Convert (3450 lbs)

HP measure was at the rear wheels through a toploader.

Measured HP: 301 @ 5200
Measured Torque: 385 ft-lbs

Luckily, at the dyno, the head gasket blew and I opted for Kieth Craft to rebuild my top end:

NEW ENGINE:
Heads: same with CK Stage II porting
CAM: Hydrolic Roller 236 / 242, .568 / .588

With this being the ONLY differences, new Dyno #s:

Measured HP: 406 @ 5700
Measured Torque: 480 @ 3600


SO, I PICKED UP 105 HP AND 95 FT-LBS OF TORQUE, EVEN BY GOING WITH WHAT KIETH CALLED THE "MILD" CAM. IT IDLES ALMOST IDENTICALLY TO THE PREVIOUS SET-UP, WITH THE SAME VACUUM (ACTUALLY A LITTLE MORE - AROUND 10 LBS AT 950 RPM).
THE HP WAS STILL CLIMBING AT 5700, BUT THE STOCK POINTS DISTRIBUTOR (NOW BEING REPLACED), WAS BECOMING VERY ERATIC AT THIS RPM. THERE IS CERTAINLY ANOTHER 10 TO 20 HP WHEN THIS IS FINISHED!

Of course I have to thank the Kieth Craft guys and Kieth who personally handled this "crisis". Next time CK will do my engine the FIRST time - it will be a LOT cheaper!

[rritchey]

Are these new numbers from a chassis dyno or an engine dyno? Either way, sounds like you are way ahead and on your way to some happy cruises.

[SCOBRAC]

So you have almost 475 at the crank.

[Dennis Kelley]

The race track and the Dyno rule. People over estimate their cars until you get to the track or the dyno. I had numerous tuning issues also. Those are great numbers. I like the torque especially. Get those points out of their. Repeat after me MSD.

[Keithc8]

These were rear wheel horsepower and torque numbers through the full exhaust system. With the new distributor and a little more tuning we may find more. I figure this would be about 525 at the flywheel. On the engine dyno the HP numbers are about the same as the torque but I believe the exhaust kills the upper HP numbers and possibly the distributor as well. Thanks, Keith

[HI Cobra]

Bet you are smiling big time now Shelbytexas.
Amazing what a difference knowledge and experience
can make!

[Power Surge]

That's a great improvement. I knew you'd pick up lots of power when you turned the motor over to KC.

What kind of chassis dyno was it? If it was a Dynojet, then 406 rwhp will give you about 450 at the motor. On a car like yours, it's about a 10% drivetrain loss. Lots of people have their opinions on drivetrain loss numbers, but being both an engine builder and chaissis dyno owner, I have seen first hand what the actual losses are. "My" loss numbers are as follows... manual with live axle- 10%, manual with IRS - 12%, auto with live axle -15%, auto with IRS - 18%. Cobra side exhaust also kills a ton of power because the mufflers are so restrictve to keep noise down, so be glad you have a full exhuast system.

[Shelbytexas]

MSD MSD MSD. Thanks for the input. I have purchased an MSD. Does anyone have a feeling for what 3 inch exhaust would do versus the 2.5 inch? The car does have headers. Remember, this is in a Shelby, not a Cobra...
Thanks!

[392cobra]

There isn't much chance you will realize your engines power with 2.5" exhaust.It just can't handle the flow.

I have a '67 rs/ss camaro with a 454 with 525-550 hp,4 speed.
It had a fairly new 2.5" exhaust and it felt retricted from about 4.5k rpm and up. I replaced it with a 3" mandrel bent exhaust with 3" core dynomax mufflers.
NO COMPARISON

The restiction changed to wheelspin from 4.5k up.

I don't know what the hp increase was but it felt like a whole different engine at every rpm.

Try it,you'll like it.

[392cobra]

Here are some guide lines.

http://www.torquetechexh.com/Web%20P...Which%2026.gif

[Shelbytexas]

Thanks 392 Cobra. I am a little surprised! Right now I have Flowmasters. What would you recommend? YEs, I want more power, but I would like to keep the noise level below the level of insanity. I have a freind with Borla mufflers. So loud you don't want to drive the thing....
Thanks for your help!

[cobraleonard]

Great success story ( but a BAD moment at the dyno I bet ). Seems to be more proof that the FE s do like the split dur/lift cams. I just read a post yeserday how they help overcome some of the restrictivness of the exhaust port . Could have been KC. I am just about ready to order my third one. The first one I bought , I thought was one of the best perfomance pieces I 've ever put in a car.