[jhein]

Originally Posted by PAUL K

I'm more curious about the quench dimension. If he makes 499.9 HP that may come back to haunt him.

LOL.

[25stevem]

If the dyno print out has a VE column what is that percentage at the rpm of peak Tq and Hp?

[Formulajones]

I doubt the carb is holding you back as your builder has stated, and it's highly unlikely the stock intake is holding it back either. Way to many 455 combos making 500 HP with that same intake system.
Not a huge difference between manifolds and headers at this power level, certainly not finding 80 HP with that change.
If you have faith in your builder let him spend more time with it and get things sorted before too much concern.
Making progress. Great feeling to finally hear it fire on the Dyno

[OCMDGTO]

Nice to know it's running and staying together. Numbers seem really low, maybe it's a stingy dyno? You might get it in the car and be pleasantly surprised?

[jhein]

Something is definitely not right. That's the kind of power I would have expected from the same parts in a 400 cid motor.

I guess we'll know more when I get the dyno sheets today. I'll post them as soon as I can.

Is it possible a dyno could be that stingy?

What kinds of things should I look for on the dyno sheets for clues?

[jhein]

Originally Posted by 25stevem

If the dyno print out has a VE column what is that percentage at the rpm of peak Tq and Hp?

What should it be?

[Formulajones]

Originally Posted by jhein

Something is definitely not right. That's the kind of power I would have expected from the same parts in a 400 cid motor.

I guess we'll know more when I get the dyno sheets today. I'll post them as soon as I can.

Is it possible a dyno could be that stingy?

Hard to say, but we've ran across that before. I remember the last 455 I put together for dad that had Kauffman ported round port Eddy heads that flowed 330 cfm on his bench, and Kauffman spec'd hydraulic roller 254/262 at .050 on a 110 LSA. It was a 10:1 pump gas engine and ran 2" Hooker Super Comp headers on it. Kauffman stated that combo makes 600hp and 600tq on his dyno.

We took it to a friend of dad's that had his own DTS dyno and right off the bat he said his dyno was stingy. He used it to compare his engines and compete in the EMC that was popular at that time and he finished well, so I knew it was a good setup.
We tried 3 different intakes on the engine, all with a 950hp carb. RPM Air Gap, Victor, and Torquer II and tried a couple different spacers on each. None of these intakes were ported in any way, they were right out of the box. To everyone's surprise it was the RPM Air Gap with a 1" open spacer that made not only the best average power, but had the best HP and TQ peaks. What was most shocking is that it peaked at just over 500hp but still made over 600tq. It wasn't anywhere close to Kauffman's projected HP claim but it did hit his torque claim. So is it that stingy on HP? I don't know.

I do know once installed in dad's car, weighing just over 4000 lbs. and in full street trim it ran easy mid 11's and I think the mph was 116+ so that falls in line with the dyno numbers. It runs the numbers I felt it should and that's what really matters.

[jhein]

Originally Posted by Formulajones

...It runs the numbers I felt it should and that's what really matters.

Well, hopefully he'll find something today, like maybe the secondaries not opening all the way or something.

Otherwise I can do some runs with my Dragy and see what I get. Of course, those results will be limited by my tires and crappy driver.

[PDC]

I’m curious to see what the headers bring to the table. I have often wondered about the exhaust flow on the box-stock Edelbrock D-ports. Edelbrock’s own testing on their own website reports 250 intake - but only 151 on the exhaust side for the 87cc D-port at .500 lift. If anyone would be motivated to provide the best possible flow numbers for the head, it would be Edelbrock.

Most on here report that untouched 6X will flow ‘around’ 170 on the exhaust side. The intake on the D-port E-head is a nice step up from an unported 6X or similar head. But I’m surprised Edelbrock didn’t make sure that their casting at least matched the factory head on the exhaust side.

I had a set of the butler prepped Edelbrock D-ports on my green car - their numbers were 290/210. And I had a pair of box stock Edelbrock D-ports on my red car. Both cars had Dougs headers and 3” Pypes exhaust. Noticeable difference between the cars above 4k.

Even though Big Red really ran out of steam by 4800, for a car to drive around town and enjoy, she made plenty of torque.

[25stevem]

The answer to the question in post 106 is that if the motor is making more corrected peak Hp then what it’s overall CID is then the stated VE better atleast be 100% or better.

The peak VE with a motor such as yours should take place at or about the rpm of peak Tq.

[Formulajones]

Again, depends on the altitude. VE changes based on the environment.

Here is a basic VE formula

Horsepower x 4235 / CID x rpm = VE

So you can look at any dyno curve and figure VE pretty easily.

In a nut shell, VE doesn't have to be, and likely will not be 100% or better for an engine to make more HP than it's size.

[Formulajones]

So if you go back and look at dyno charts that Cliff and I both posted, both having a fairly high correction factor for obvious reasons. Using that formula they both come out to nearly the same VE percentage.

Cliff's 455 came out to 89% VE and mine came out to 87% VE at peak HP. Both engines made more HP than their size.

[unruhjonny]

maybe you guys can clear something up for me;

I am more used to discussions on vehicle dynos (as in ones where the car is strapped down;
In the course of one of these discussions, inevitably elevation, conditions, and the applied "correction factor" to the dyno is always brought up.

Do engine dynos also use a correction factor?

I ask this because this tends to play too often into the "other" dyno discussions - where two cars which run the same, are dynoing (oh lets say) fifty horsepower different - and you know that it's entirely on the dyno.

... and this brings me back to what I tried to say before;
often people put too much weight on the actual numbers that the dyno spits out, and spend less time on absolutely optimizing everything, or using the dyno to super tune it.

Maybe I'm completely off here?

[Formulajones]

Yes dyno's use a correction factor, and that varies depending on where you are located, weather conditions etc... If you just use a standard number for everything they will be vastly different.

The same naturally aspirated engine isn't going to make the same HP at 6000 feet as it does at sea level. It just won't, the air is thinner up here. Correction factors sort of put that in a more level perspective for comparative purposes.

As a general rule of thumb for quick math, you lose about 3% power for every 1000 feet you go up in elevation on an NA engine. Go up 6000 feet and that's 18%. That's a pretty big change, especially when you get into 500-600-700hp engines, the worse it gets. 18% on a 700hp engine is 126hp.

[25stevem]

What was the peak air flow on your test and the CAT?

The ultimate dyno sheet in terms of the HP being made is your MPH on your time slip from a 1/4 mile pass.
Do you have any of those to share?

[mchell]

Originally Posted by jhein

Well, hopefully he'll find something today, like maybe the secondaries not opening all the way or something.

Otherwise I can do some runs with my Dragy and see what I get. Of course, those results will be limited by my tires and crappy driver.

Well…sometimes, it is what it is

For what it’s worth, I have NEVER left an engine or chassis dyno that met my expectations …

My first iron headed 455 build with ported 96 heads netted me a whopping 432 on the dyno if I recall. A buddy just dyno his stock build(mostly) 70 455(70 455 heads)and netted 387hp

Don’t get too worked up with dyno chit….

[R 70 Judge]

Slap the headers on it, tune it, and call it a day. I'm sure it is making at least 130hp more than your previous RA3 engine. That is a huge difference so don't get hung up on the dyno number. With the stick it will be an absolute blast to drive!

[jhein]

OK, before we get into the Dyno sheets, we have to have a couple glamour shots,

[Formulajones]

That's look great

[jhein]

Dyno graph with RA manifolds



Dyno sheet with RA manifolds