428 CJ Dyno Results....Inquiring Minds...

[Clois Harlan]

I have just returned from two hours on the Dyno:

My results are a little disappointing. I am running a 428 CJ bored .060 over with TRW 10.1 forged alum pistons, Lunati 512/292 hyd cam, Edelbrock Alum Medium Riser heads, Edelbrock Performer RPM intake, MSD FE Distributor, MSD 6AL ignition box and coil, 8mm Ford Motorsport plug wires. Champion 71 plugs , Holley 750 carb (I also tested the Edelbrock 750 and lost 28 hp)w/ Holley red elect fuel pump and regulator set at 6 pounds.

My first pull on the dyno was a solid 362 hp and 391 ft pounds of torque at 5800 RPM at the wheels. Torque was flat from 2000-5200 RPM and then fell off to 387 at 5800.

We changed the timing to 10 deg initial and all in by 34 deg 3300 rpm. We put in the two smallest blue springs on the dist and lost about 9 hp on the second pull. Next we switched to the two med silver springs and still lost 13 hp on the third pull. Put the med silver spring and blue spring back in the dist and made a forth pull and my hp came back to 363 hp at 5800 rpm.

Carb: Was perfect on the primary's but the secondaries were loading up and was not able to open the secondaries up completely. Went to the smallest spring avail for a Holley vaccuum secondaries carb and down sized my secondary jets to 74. Made several other pulls on the dyno and the best I could do was 371 hp and 393 ft pounds of torque. Chad told me that it is normal to loose up to 150 hp from the fly wheel to the rear wheels.

His suggestions were to go with a mechanical Holley or Demon carb (up to 850), Autolite plugs and change my air filter to a KN and don't oil it. I tried one of his KN air filters but my hood wouldn't close and I only gained about 4 hp on my last pull. I am going to think about another carb for awhile.

Any way those are my results which were better than the SS 396 before me (his best pull was only 323 HP and 335 pounds of torque. Still think there is another few horses for me to gather up some day.

[Jeff Frigo]

Chad told me that it is normal to loose up to 150 hp from the fly wheel to the rear wheels.

Actually, Chad is way off. A 15% - 20% loss is a generally accepted loss from the flywheel to the raer wheels. Maybe he is trying to make you feel better.

Your numbers are not as far off as you may think. Lets do this ass backwards. 371 rwhp equates to 449 fwhp if you fiqure a 17.5% loss. Add another 50 hp for losses in the side pipes and you are up to 499 fwhp. Torque comes in at 524 fw ft lb. These are numbers I would expect to see from your combination.

[Clois Harlan]

So Jeff would you be disappointed with these results? I had calculated the numbers based on orig hp and then the advertised add on hp etc and came up with around 500+ hp. The fact is the car is probably capable of doing a lot better than the driver is comfortable driving. Not so much at the drag strip but on road courses I need a little more experience. Racing slicks helped my confidence out a lot but I found out that when they let go it is already to late to do much about the situation.

Thanks for the input.

Clois

[Jeff Frigo]

Clois

When you look at the rear wheel hp, they do seem low, but if you recalculate like I did for you, numbers are good. I made 585 fwhp @ 6,000 rpm. with an engine with a lot more work on than yours and am very happy. Mine is a 27 with a 28 crank (454 inches) about $2,000 worth of porting and a bigger cam (.620 / .626 lift, 258 / 260 deg. @ .050). This is a pump gas motor, Edelbrock was very impressed with these numbers.

The other thing that most people don't realize is how bad stock side pipes are. Cut out the muflers and replace them with a set of Dyno-Max's. A 50 hp jump at the rear wheels would not suprise me.

[Clois Harlan]

Jeff I am impressed with your power. By any chance will you be at the Run and Gun in St. Louis?

I hope to have a little more hp by then. I know I don't have all the tools yet to win but I do want to be somewhat competitive.

Clois

[Whaler]

Hi Clois
Thanks for posting the results of the testing

Questions......

Are you using a windage tray?
Are you using a march pulley setup? Underdriven stuff is what I am getting at

What was your initial/original air breather for these runs?

I have really about the same engine except went with the RPM cam as put in the RPM edelbrock package. Opted out on their edelbrock carb and went with Holley 850 w/mechanical secondaries. Also a little different, I have the MSD 8 mm wires and am using accel 416 plugs gapped at .40

As I had asked before, I was really curious about your initial timing and advance set-ups for the MSD. I have yet to go there and do this fooling around so this is very helpful info for me

I know also on my car, that my builder made up a new sidepipe design and that when he tested it he got considerably more HP out of it over the old ones he was building for his cars. He claimed 40-60 HP

I know what you mean when you talk about fords original HP claims....345 HP on the std 428 . They also say they were kept down conservatively as well.

Keep us posted

Tim

[Jeff Frigo]

Won't be in St. Louis, but am going to the strip in the next couple of weeks. I will let you know. The trick to making hp is in the heads. Find yourself a good porting guy in your area. Should be able to get around 330 cfm on the intake side at .650 lift.

[scr11]

Jeff - Good point about the sidepipes. After having my custom 393 stroker on the Dynojet (chassis dyno), I was disappointed with my numbers as well (391 rwhp and 386lbs of torque). At first, I was perplexed. With a 15% driveline loss, that's only 460 at the flywheel. My motor was built with a 520hp flywheel combination. So, I was about 50hp (rear wheel) short of what we expected. I have stock Superformance pipes and I've been told the same thing - they probably cost me about 30-35 hp. Hard to believe, but those damn pipes are way more restrictive than people think.
Anyway, to boost my ego, I may go back to the dyno one day and remove the pipes and run with open shorty headers to see the real difference.
In the meantime, do you know where I can find any photos or sound clips with the mufflers you mentioned welded into the sidepipes? Does it look decent?

Thanks.
Scott, SPF#1230

[wilf leek]

Clois - those sound like good solid numbers, and if you still have good "streetable" engine, fine!
Headline HP figures mean little compared with how the thing drives - I stayed out of a "wilder" cam, intake and stuff to retain an engine that pulls whenever I want, from whatever revs I am at.
Did the carb set-up cure the stumble???

[Jeff Frigo]

Wilf:

Sorry, no pictures or sound clips. If you do a search, you will find much more info. on this topic than I have provided.

[Clois Harlan]

Wilf,

The carb did cure the stumble and I can drive it hard at any time without any hesitation. As it turned out I had a vaccuum leak in one of my plug off caps. I really have plenty of power for the street and most race events I will go to. Just a little testarone thing (I hope I spelled that correctly).

[Clois Harlan]

Sorry I had to check back on some of your questions. I have a windage tray but chose to take it out after pulling my pan about 8 times it became a hassle. I am using March pulleys on the alternator and water pump. I am also using a Edelbrock water pump. I am using a 13" chrome 2" air filter (nothing special-whole thing cost me $20) I do have a KN valve cover filter but I think that may have been a waste of money too.

Sounds like our engines are similar so if you go and have yours dyno'd let me know your results - just for comparison. I would be interested how many more horses you will get out your set up using a mechanical carb.

Clois

[wtcobra]

Clois-did you try the total timing at 38? It has been my experience that 38 works best most of the time on these motors, with all the timing in as quick as possible.

Wayne Turpin

[Jeff Frigo]

Mine made the most hp @ only 33 degrees, all in by 2,000 rpm. Remember, the more efficient the engine, the less timing it needs. Pro Stock motors only run about 20 degrees total.

[Whaler]

Clois thanks for the info

A call to George A. at Gessford gave me the following advice.

Initial at 10-14 deg. and total being no more than 30-34 deg. have it all in by 2500-3000 rpm for our 428's Lots of initial lead, as much as it can handle.
Primary and secondary opening about the same.

"We changed the timing to 10 deg initial and all in by 34 deg 3300 rpm. We put in the two smallest blue springs on the dist and lost about 9 hp on the second pull. Next we switched to the two med silver springs and still lost 13 hp on the third pull. Put the med silver spring and blue spring back in the dist and made a forth pull and my hp came back to 363 hp at 5800 rpm. "

So obviously going to the slower advance curves starting working against you....first 9 hp then 13 hp....going to the blue and light silver is one step away from being at the quickest advance curve which is two light silvers. Wonder how that may have worked out?

You have to work with what you have and what else can a guy do in the setup while powertuning??

Tim

[Clois Harlan]

Tim and Wayne,
Actually, we did run the initial advance up to about 14-15 degrees with the total timing at about 37-38 and we made more hp but we found that the old engine would diesel uncontrollably after shut down. We could make a little more hp at different set ups but we compromised other things. This is the best all around set up we could come up with for the street at this time.

Like I said I may try some other things later but for now I am going to park it for awhile and take a little vacation. My wife and I are off to Florida for a week or so. Hopefully, I can get by and see Enzo and Paula next week.

If there is anyone in this area wanting to put their cars on a dyno Chad at BJS Cylinder in Tulsa has the best price going. I spent a total of $120 for over two hours on the Dyno (14 pulls). Chad told me that the HP Performance guys from Omaha were down earlier in the week and that several of the local Nascar trucks are regulars. My only concern was that most of these guys wore Bow Ties!

Wayne, looking forward to seeing you at Run and Gun. David (Kansas City) and Lew (Milwaukee) and I just made our hotel reservations.

Clois

[Andy Dunn]

Hey Clois
those numbers look close to predicted but I think you might be able to find a few more HP like you said. Here are the possible numbers from dyno2000

I believe you stated the rear wheel results were
HP 371 @ 5500
TQ 393 @ unknown

Dyno2000 flywheel results were
http://www.cobralads.com/dyno2000/428_cj1.gif
HP 446 @ 6000
TQ 447 @ 5000

if we take off 15% for parasitic drag and 5% for sidepipes
HP 357 @ 6000
TQ 358 @ 5000

and that is an error of less than 5%.

CARB
I think you might find a few more HP with a new demon carb or high end holley. Here is an example
http://www.bgfuel.com/demoncarbs/demon_charts.htm

One thing to note, if you go with a road demon or a vacuum speed demon, you will not see an increase in peak HP, but you will see an overall power band increase throughout the range, but the peak HP will not change much. I believe that the low-end and medium Demon carbs with vacuum advance, go rich at the top as a safety precaution. Ryo and I saw this at Westech. John Baechtel explained it to us. If you want to achieve maybe 15-25 more peak HP, I would go with a mechnical speed demon or race demon, or higher-end holley. like the two nascar 830 models.
http://www.bgfuel.com/demoncarbs/products.htm
http://www.holley.com/HiOctn/ProdLin...C/0-80785.html
http://www.holley.com/HiOctn/ProdLin...0-80509-1.html

The trouble with these carbs is "price" and you end up paying $1000 for 20HP which may be worth it to some and not to others. You actualy gain more than peak HP though. It's amazing to see on the actual dyno the way the demon carbs can increase the width of the graph 15-20HP from 3000-5500.

TIMING
I personally don't think MSD spring adjustments have anything to do with "peak" HP and TQ on a dyno and here's why. These springs determine "when" the distributor is at FULL advance or "ALL IN". Here is the tech page from the MSD manual
http://www.cobralads.com/msd.gif

Even if an engine has the slowest advance rate (2 large silver springs) and the red bushing, the distributor is still all-in at 5500. If peak HP is at 5800, the springs had finished doing their job 300 rpm ago. In the case of your 428CJ, a medium silver and a blue, I believe this means the distributor was all-in at 3500, from that point onward, the engine is at total advance. I think what you were seeing in each run where springs were adjusted, is just common variations because of temperature, barometer, and engine heat. Someone please correct me if I'm wrong...I believe an engine wants the fastest advance curve possible (without detonation). This is to achieve the strongest overall powerband. TOTAL timing directly effects peak HP, not the timing acceleration curve?

SPARK PLUG
I am skeptical of 99.9% of spark plug tricks, but here is an interesting one from the August FF&MM. This trick is supposedly worth 5lb TQ on a stock mustang. If you look at the electrode on a plug, it is long. Cut it back and camfer it to be cenetered. In testing, this gave 5lbs TQ extra from 2000 an on in a stock mustang. MMFF confirmed the test. The author also wrote that he had seen up to 20HP when switching to Autolite AR133s in a stock 5L.



hope this info was interesting

Andy
http://www.cobralads.com

[ERA535]

Andy -

Consider that the need for the intial timing to be where it is so that the thing will even start...

The timing doesn't just bang over to maximum advance then.

It has to be variable and dependent on rpm because of one thing:

The flame, once started, takes a set amount of time to burn completely. The faster the engine revs the less time it has to do that so it has to start earlier - this is called advance - and the faster the engine revs the more advance you need - up to a point.

Pat

[Andy Dunn]

Right Pat, I agree. Maybe I am not making my point clear.

The "timing ramp" or "distributor advance curve" on any engine has no effect on peak HP or TQ. The "total timing" of a distributor does effect peak HP and TQ. By altering the "timing ramp" or "distributor advance curve" with the springs, changes the shape of the HP and TQ graph up to the point where "total advance" occurs. I believe proof of this is that some race cars are just lock at total advance to avoid trouble with the weights. Racer's would not do this if it effected their peak HP and TQ.

Page 101 of Smokey Ynunick's Power Secrets
First of all, our testing has shown that at engine speeds above 1500rpm, a racning chevy on gasoline requires a contant amount of advance. In other words, at racing speeds, there is nothing to be gained by utilizing the operating mechanism inside the distributor to provide additional spark advance. This mechanism is the primary source for timing irregularities, and when it is eliminated or made inoperative the distributor will provide an accurately timed spark to each cylinder. On the conventional delco type distributor, we usually disable both the centrifugal and vacuum advance systems and lock the mechanisms in the fully advanced position. Once this is done, the initial timing is set and the engine turns with a constant amount of advance at all speeds.

and Smokey would never do anything that adversely effected HP

thoughts?


Andy

[ERA535]

I wish you had quoted someone else!!

I have a lot of respect for Mr. Yunick.

I have always felt the lack of need for variable advance on a RACING engine was because they operated in such a narrow power band and at such high rpms' that variable timing was a waste of time. I agree with Mr. Yunick.

A street engine that has to perform at a wide range of engine speeds may be different?

Also - while the peak power may not be affected by the curve - I do believe that peak power may not be as important as power developed through the rev range..

I do have a question though - when was the Power Secrets book written? Could it have been before the advent of modern ignition systems?

Pat