Like BradH said, those computer programs are a joke. Take it to the track and run it.

well, my last experience with the engine was not a good one, so engine dynos are out. chassis dyno maybe, now my plan is to get it out to the track next year. it still needs an alignment and gear change. I think my good weather is gone for the season as well. I agree, a time slip is always the best.

Like Dwayne said, sometimes those programs are real close. My 408 was off by 12hp.

Definitely not what I said.

Several years ago I ported a set of SB rpm heads and sold a roller cam to a Moparts member for his bracket race challenger with a 419 stroker in it.
He was looking to improve his combo to run solid 10's.
He messed with it for a full season...... Never got his 10.
Converter changes, gear changes, all kinds of small stuff..... Car was stuck in the low 11's.
Motor hadn't been dyno tested....... No telling what it actually made.
He was thinking of making some pretty significant motor combo changes in his quest for 10's.

I told him that his motor combo should be making 575hp.
But without knowing the quality of the machine work, etc...... Perhaps it wasn't making what it should.
He was convinced the motor was just not making the power it needed to for him to get into the 10's.
I suggested that before he pulls it all apart, to just take the motor out and have it tested, so at least he could see what it had, and how the car was running compared to what it "should" run.

He couldn't find anyone near him who was set up to test a Mopar, so he crated it up and shipped it to me.
He sent his headers, carbs, timing light, etc.

I put it on the dyno, warmed it up, set the timing with his light to where he said it worked best....... And made a pull.
576hp

There was nothing wrong with the motor, he had things that needed sorting out in the car.

Armed with that info, he approached the lack of performance as a "car" issue, not a motor issue.

New converter over the winter, trans redone, wiring, fuel system upgrades, etc.

Put the motor back in just as it was when he pulled it out.
10.80's off the trailer......... Ultimately that combo ran 10.60's.

Later on, a little more porting, bigger intake valves, and a more aggressive cam had it running 10.40's at around 3450lbs.

Not really what I said there either.

I use the power/speed charts and calculators to gauge how good or bad the car is at making use of the available power.

If you don't know what the power is to begin with, then they aren't all that useful
IMO.

From what I've seen, the "typical" street/strip or bracket car should be able to run within 10% of what the Moroso chart shows for power and weight.

If the motor makes 500hp, the car should be at least able to show 450hp on the Moroso chart.
Really good cars will be much closer to 100%...... And once in a while a combo will show better than 100%.
But, without dyno numbers....... You don't know where you really are.
Is your combination 100%, 90%, 80% efficient?

Isky has my cam card on file and I will shoot ya my specs later.......run it no matter what anyone says and enjoy what I do daily..........haulin ass, docile on the street and easy 9's..........

You think another 50hp is going to change that?
I wouldn't count on it.

If you want to be scared, better start formulating a plan for around 850-900hp.
Start saving for that turbo kit.

I'll admit that when I first test drove my hemi, it shocked me. It makes somewhere around 825-850 hp...the 440 it replaced made a little over 600 hp. That was a big jump.

If an engine is going to let loose, it's going to do it in the car just as easily as on an engine dyno.

Did you trace your engine dyno incident back to the root cause? Such as:
1. Dyno operator not experienced and/or did something stoopid that hurt the engine like over-heating it
2. Engine built properly, but had a legitimately unexpected parts failure on the dyno
3. Engine not built properly and that reared its ugly head on the dyno

I've done four engine dyno sessions over the last 20 years. A couple of them encountered no issues at all. One in particular definitely helped identify some issues with the valve train that would have been far less "convenient" to have run into driving the car miles from home.

You've run faster than I have by a couple of tenths, so I'm sure you'll figure it out. However, some of the things you said -- like the above comment on engine dynos -- leave me scratching my head.

LOL! yur probably right. After riding sport bikes, it would be tough.
Sorry for the misunderstanding.

thanks Dom

Dont forget, Doms car runs in the 9's but its considerably lighter than yours is.
You add on that weight its no guarantee yours would.
Before i ran a cam somebody with a different car/ combo/ weight runs i would give that more thought.
Its all about YOUR combo and what it might like.

No I never did. It was my 5th engine I have put together. not a pro engine builder, but I built it with more attention to detail than any of the previous motors. I still don't think it was my fault, but who knows. The shop owner and I do not get along after he charged me for flowing some heads that had flow numbers the matched the indy flow sheet perfectly, every number at each lift.I get along with his son who runs the shop and is a good tuner I thought. I dropped the engine off 3 days ahead of time so he could get it hooked up. Fired it up and had to shut it down because a plate he had between crank and output shaft was rattling. don't know how long it ran like that before I got there. fired back up 80# oil pressure once hot, made 5 pulls and it cam apart.
https://youtu.be/hgoORq5ryWw
I now understand they blow up a lot of motor on that dyno.

well, I currently have a cam it that was spec'ed for the motor.

I've done four engine dyno sessions over the last 20 years. A couple of them encountered no issues at all. One in particular definitely helped identify some issues with the valve train that would have been far less "convenient" to have run into driving the car miles from home.

I had the same thing happen to me, and I was very glad it was on the dyno.
My Hemi is not living up to my expectations using the ET / MPH calculators ,so it will be going on the dyno .

Mark

True so let's see a chassis dyno w/it as is then try my cam and I was 3200+ went I went my first 9.79 at 135.59 lean as hell............I like to lead not follow............

well, that's about 180# difference. Your motor would run circles around this 511. I think your cam and more compression is the answer.

I had it ground for me by me and couldn't be happier and generally when someone suggest a cam for you, they fall short on duration and lift imo and NEVER say street driven...........MOPAR's like fuel, compression and go faster 99% of the time IF you have the right gear and converter then there's the carbs........More is usually better as well and no 4150's on Big Blocks either............

I'm sure that 276/281 roller would really spike up the cranking pressure numbers.

Not sure on that Fast cos I only have 175 cc but may need to check again and may even add some timing since the RPM's have a crappy stock-like chamber...........