543 going to the dyno- with HP &TQ NOW

I have seen a few of these posts lately. I would love to see what you guys think it will make-

Mine is getting dyno'd on Friday

4.380 bore x 4.5 stroke
10.5 to 1 compression
Victor standard port heads- cleaned up and flowed 325 cfm at 550 lift
solid roller cam, 575 lift and 262 @ 50 110 LSA
T&D roller rockers
Victor intake
Holley EFI- with 1100 CFM TB
2 1/8" headers stepped

I'll take the bait.. 695HP/720 torque. What's it going in?

625/675.

Victor heads aren't my thing but if they are working correctly I'd expect to see something around 650/650. The cam isn't big enough to make big numbers so I'm assuming you kept it on the small side because it is a street car?

Yes, it is for a 1968 Barracuda 4 speed street car.

I replaced the Old solid roller that was .680 lift and 292 duration @50 with the smaller street friendly cam tht is in it now.

4.10 dana 60, 18 spine A833 and twin disc clutch.

I am hoping to see 650 + HP and TQ.


One more minor detail i negelcted.

Also.... its in the car and its a chassis dyno. I already did a remote tune with Richard Nedbal. Based on BSFC Nedball thought it would be a very powerful motor. 750+ HP.

I am going to see about adding some timing to see if it likes it. Its set at 34 now.

Why do you not like the Victors?

They are just a weird design. Lots of threads on here talking about the Victors. They do seem to work okay once they get all sorted out so if the engine is running for you and making power don't worry about it.

What chassis dyno?

Rear wheels/tires?

Exhaust after headers?

If a dynojet, my guess is-

630rwtq @ 4200

525rwhp @ 5500


If a Mustang dyno, -10%

If tubbed on huge wheels/tires, -40rwhp

If exhaust is smaller than dual 3" -or- any muffler design other than straight through. -40rwhp

I think it would be difficult to make 750 with 325cfm and that displacement/cam/compression so thinking it will sign off a bit early.

I agree.......and would be very surprised to see 750 from that combo on the engine dyno here.

I mean......”never say never”, but until I saw it do it here with my own eyes........ it’ll just remain in the “highly unlikely” catagory for me.

Okay- it went pretty well, no issues with the car other than inth 4th gear at 6500 rpms the tire grew and grabbed the edge of the quarter panel.... some minor damage.

Ill post the dyno graph later, my phone died. I sadly suck at taking pictures and only took a pic of the 2nd run screen. We did 3 pulls total and the third was the best, not by much more, but it was the best.

3rd pull it made 531WHP and 597 Ftlbs to the wheels!

Its a street car, i ran it with its exhaust on, 4 feet of pipe and summit turbo brand mufflers, and a air cleaner in place. 91 octane pump gas, straight from safeway gas station. 295 / 65 / 15 MT et streets

I guess its a respectable number.

The owner / operator of the chassis dyno says he consistanly sees around 18-21% HP loss through the drivetrain. If that is reasonable to assume it means the motor makes about 630 flywheel hp and almost 700 TQ.

The numbers are impressive to me
I’d love that torque.

Here is a pic of the first 2 pulls.... I didnt take a pic of the third run. but it was a little better.

Im not sure why each run got a little better, he let the car cool down a bit between runs and i drove it to the dyno. about 17 miles from my house. it was warmed up.

Also the first run the tire grabbed the passenger quarter panel and buckled it, lots of smoke and such. I belive that was why it was the lowest pull.

All pulls were in 4th gear.

I do like the torque from 2500 rpms to 5500 pretty substantial.


The trans is a 18 spline 833- what would you shift at to make the most efficent runs?

Shift it between 5000 and 5500

Take it to a track and find out what the cars likes as far a shift RPM, try 5500, then 600 and 6500 RPM
look at the 60 Ft. times and 330, 660,1000 Ft. and finally, the 1/4-mile times.
My last pump gas stroker motor made peak torque at 4500 RPM and peak HP at 5500 RPM on several different engine dynos but the combination like to be shifted above 7000 RPM at the track for best ET and MPH
Theory is one thing when it comes to our hobby and real world results can and sometimes don't follow theory, the only way to learn what works the best on your parts is to test, test and then test some more

Those are pretty good numbers.

I’d actually expect to see more than 630hp on an engine dyno.
Lots of losses in the typical street car.

You always shift after peak HP. You want max average horsepower going down the track.

Nice numbers! What was it SAE?

Less

I have found on a Dyno Jet its about 13 % loss from Net flywheel HP

My old pump gas Duster lost 30% HP due to drive train loss and the converter not being really efficient until above 6500 RPM
I ended up having to shift that motor above 7000 RPM to get the car to go as fast as it did
Don't be afraid to test at the track
The only thing that I rely on is the time slip and spark plug reading when it comes to testing and tuning