Jacque Vizard Memorial 302 Dyno test

[David Vizard]

Some interesting guesses here with one right on the money but before going into that let me make a few points here which may help when you are estimating the torque and HP of your own builds.

First torque output from a conventional SB 289 -347 short deck Ford with a CR in the 10/1 range. Because of typically low swirl values and the fact that the shorter deck also means slightly shorter intake runners on a conventional two or single plane intake low and mid rpm torque is harder to make than with a SB Chevy of 302 cubes.

Look at tests done by Ford specialists with a rep for producing good motors and you will find that for a 306 (0.030 over 302) torque output for a pump gas motor ranges from about 373 to 400 lbs-ft with 385 being common. This covers the range of 1.22 to 1.31 lbs-ft per cube. so for a torque guess the 1.31 number should have been a guide assuming you thought I might know what I am doing (if not a lower guessed number would apply). So If you used a good figure for torque i.e. the 1.31 lbs-ft number then you would have come up with 400 lbs-ft. but trust me only a small percentage of true street (that is with Vac sec carbs vacuum advance etc.) SBF's make that kind of torque on 87 octane pump fuel. So let’s say that 400 lbs-ft is peak torque.

Now for HP. How would you make a guess on that. First take a look at the cam and estimate what rpm it might deliver peak power at. The cam here is a special Comp profile ground to my event specs. It has 270 degrees duration on both intake and exhaust. Allowing the fact that AFR produce some damn good heads we can sy that such a cam would probably produce peak power at about 6100 rpm.

If we have a number for peak torque a good estimate of peak power can be had by multiplying peak torque by 0.9 then multiplying that answer by estimated peak power rpm and dividing that by 5252. Let’s see how that works out. HP = 400 x .9 x 6100 /5252 = 418 hp.

So 400 lbs-ft an 418 HP would have been a good guess assuming I could spec out a build at a level that compares well to top engine builders. If this motor makes better than that maybe it’s a build that a prospective SBF enthusiast would like to replicate.

Tonight I will put up the power/torque graph as it will appear in the SB Windsor Ford book I am working on.

[ap72]

I followed a simmilar line of thought but used 1.5 instead of 1.31... This is David Vizard after all.

[David Vizard]

I followed a simmilar line of thought but used 1.5 instead of 1.31... This is David Vizard after all.

Thanks for the vote of confidence.
DV

[woodaca3680]

I pretty much followed your explanation to arrive at my answer based on the numbers i would expect if i had built that engine.I guess i need to buy that SBF book.

[David Vizard]

408 hp 385 pound feet torque

your guess was a very viable one but just not quite high enough.
DV

[GARY C]

Can you show us the full cam specs? as well as both dyno sheets 4* vs 6* advance? It would be nice to see the overall power curve.

[David Vizard]

Can you show us the full cam specs? as well as both dyno sheets 4* vs 6* advance? It would be nice to see the overall power curve.

Gary, this was a build to show what can be done with info rather than a dyno. It was built with off the shelf parts and assembled as I intend to detail it in the book. The average guy does not have a dyno. Just a few guys will go on the dyno to prove the build out but won't have spare cams or an expensive belt drive to optimize the cam. this motor was put together based on what I know of the characteristics of the heads camshaft etc. If someone follows the build to the letter then they will get the results I did with no more than a good carb tune. The book is after all about building with a limited budget.

DV

[GARY C]

Can you show us the full cam specs? as well as both dyno sheets 4* vs 6* advance? It would be nice to see the overall power curve.

Gary, this was a build to show what can be done with info rather than a dyno. It was built with off the shelf parts and assembled as I intend to detail it in the book. The average guy does not have a dyno. Just a few guys will go on the dyno to prove the build out but won't have spare cams or an expensive belt drive to optimize the cam. this motor was put together based on what I know of the characteristics of the heads camshaft etc. If someone follows the build to the letter then they will get the results I did with no more than a good carb tune. The book is after all about building with a limited budget.

DV

I assumed the info I asked for would help the average guy understand the benefit of using COS cams and following your builds...Although I have read and for the most part followed everything you have written and my last 4 builds have had cams specked via your software (successfully I might add) if I have no data to study and learn then my knowledge stops me from building something outside of what you write about.

[David Vizard]

Can you show us the full cam specs? as well as both dyno sheets 4* vs 6* advance? It would be nice to see the overall power curve.

Gary, this was a build to show what can be done with info rather than a dyno. It was built with off the shelf parts and assembled as I intend to detail it in the book. The average guy does not have a dyno. Just a few guys will go on the dyno to prove the build out but won't have spare cams or an expensive belt drive to optimize the cam. this motor was put together based on what I know of the characteristics of the heads camshaft etc. If someone follows the build to the letter then they will get the results I did with no more than a good carb tune. The book is after all about building with a limited budget.

DV

I assumed the info I asked for would help the average guy understand the benefit of using COS cams and following your builds...Although I have read and for the most part followed everything you have written and my last 4 builds have had cams specked via your software (successfully I might add) if I have no data to study and learn then my knowledge stops me from building something outside of what you write about.

Gary, that last part on your post left me confusssed!!!

DV

[David Vizard]

Well here it is - the power curve for the JVM 302.
The correct answer for the peak outputs was 411 lbs-ft and 431 hp and it all starts from 1500 rpm up and the vacuum is about 14 inches.
This is an off the shelf build with no special machining or hand work and can be built at home with a regular set of Craftsman tools.
The principle reasons for this engines success is that the combination has great comparability and that is something I try to instill in my students during my university seminars.

For this build the key factors toward success was firstly the selection of good cylinder heads (some interesting F/bench data if anyone is interested). Secondly giving the heads what they and the displacement/CR needed in terms of valve e vents and thirdly great machining and bore prep like most engine shops are not using.

[MadBill]

Wow, EthylCat, you blew it by a whole 1 lb-ft. and 1 HP! A dyno would be a waste of time for you!

[ou812]

This is an off the shelf build with no special machining or hand work and can be built at home with a regular set of Craftsman tools.


For this build the key factors toward success was firstly the selection of good cylinder heads (some interesting F/bench data if anyone is interested). Secondly giving the heads what they and the displacement/CR needed in terms of valve e vents and thirdly great machining and bore prep like most engine shops are not using.

David, would you mind letting us know what special bore prep your doing cause I'm confused about the first statement and then the fact that your doing the bores "special"...Just curious...
Brian

[EthylCat]

[quote="MadBill"]Wow, EthylCat, you blew it by a whole 1 lb-ft. and 1 HP! A dyno would be a waste of time for you! [/quote]

Woohoo! This means my system kinda works. I have several engines out there that I have run the same way data wise that have never been dyno'ed so I am happy that I may have gotten close to what I designed them to make. OR I am a blind squirrel that just happened to find a nut.

I do not deserve any credit really. I use a combination of Dynomation 5, Engine Pro, Pipemax , a little experience and some gut instinct. Give the credit to the smart guys that designed the software. It is actually pretty amazing how good all three are. I just have kinda figured out what numbers are most accurate and what numbers from one should be entered into the other to arrive at a final answer. They all have there strong points.

More credit goes to Mr. Vizard for building such great engines and then sharing the experience, specs and results for us to learn from. Thank You Sir!!!!!

I also use the three programs to pick out cam specs since no single one gives me all the info I want. Mr Vizards information is going to help my inputs to hopefully improve my decision making. The process is hardly as set in stone as Mr. Vizards, ,Chris Straub, Mike Jones or any other cam specialist, but I think I am moving forward.

One of my next projects is to go thru all of my sims using the 128 method to see how it matches up to what I have done in the past and hopefully see the trends which require slight movements up and down with that number.

Congrats David on such a fantastic build and you can count on me to be first in line for the Ford book when it is complete.

[novadude]

I'm going to buy the Ford book and I have no intention of ever building a Ford.

[David Vizard]

This is an off the shelf build with no special machining or hand work and can be built at home with a regular set of Craftsman tools.


For this build the key factors toward success was firstly the selection of good cylinder heads (some interesting F/bench data if anyone is interested). Secondly giving the heads what they and the displacement/CR needed in terms of valve e vents and thirdly great machining and bore prep like most engine shops are not using.

David, would you mind letting us know what special bore prep your doing cause I'm confused about the first statement and then the fact that your doing the bores "special"...Just curious...
Brian

Sorry, this was a dig at those folk who said I should leave out (among other things) bore prep as this has been done to death. Really - i have not seen anything like my method in any other books but I do know it is used in some of the worlds most successful engine shops. Having said that the most radical bore preparation is off the cards here. Maybe down the road I can tell you about some F1, BTCC motors and the like that is still under wraps. What i can tell you is that it is close to mind blowing.
DV