General Question?

[billetbirdcage]

Sidebar question, i see all / most of the big boys run Fords, why is that?

My only experience with Fords are really not racing related, but high performance engines. They always seemed to be softer on the low end, and pull for days on the top end. Which in retrospect thats kinds what were after.

Opinions are gonna vary on this, but the major factor IMO is this:

It's not really about the brand (ford, chevy, mopar, and etc) but the research put into one basic combo for a dirt late model. Roushe/Yates just happened to be the one that was willing to go all out and combine that with their existing engine experience it ended up being a ford. It could have just as easily been Hendricks or someone else with a different brand of engine.

That being said, the RY45 is thoroughly tested and a ton of the expense is done for you if you just follow the parts they use 100%. I think the problems you see with the fords from other builders is because they start or just do their own cam design (trying to improve) and don't do the testing needed like the spintron testing. If you just use the Roushe/Yates parts (I do mean down to the tee or one small thing like valve locks, or anything with a slightly different weight or frequency) then it can beat up the valve train and cause a failure. Many aren't going to spend the money for this, I know I've had it done and it's not cheap and one change it needs to be done again.

Again the failures with the fords whether it be bad parts here or there or other engine guys trying to improve it without doing all the steps is in my opinion more the later. Again not throwing any builders under the bus, but IMO at first there wasn't many failures besides the bad part deal that happened and it got worse lately as more and more builders started doing the fords and the previous builder having to many customers that wanted something better then what everyone else was getting thus started changing stuff. Just my opinion some based on fact and some based on assumptions, but then again what do I know I'm not an engine builder, lol.

I can tell you the RY45 will run a lot more laps and turn more RPM safely then any of the other engines I've been around and look absolutely perfect when it comes apart for a freshening. I know guys running 30 to 50% more laps then they was able to on their other top named engines.

[Kromulous]

One of these days i am going to have the time and means to do this sort of thing, Dyno motors all day, build race cars etc. I cant wait !

So the leading candidates for TQ falling off to soon to make good power, is the Cam, Carb and timing either valves or ignition.

I heard it said once that an Engine should make 2* the flow numbers on the Intake runner at max lift, and if its set up properly (Cam Carb Timing) it should make 5% more. Its eery how close we are to that, its at 2 times the max lift flow, but not the 5% so i guessing something is off. We shall look on to it more.

As for the Fords, they look stout on the track i will say that. Although Coronett seems to be making a bit of a surge with there 10* stuff lately.

LOL another thing i thought of, Dyno testing on a roller, in car deal, how much parasitic loss can i count on? 10%?

[billetbirdcage]

Torque falling off: Can be a number of things, typically a short stroke big bore doesn't do it as bad as a long stroke and smaller bore. This is why we have spread bore engines to allow larger bores then was possible with the std bore spacing of 4.4" on a STD SBC.

1. Stroke/bore combo
2. Cam small or wrong for desired RPM
3. Head or intake system too small to feed that large of a CID engine
4. Sub par ignition
5 Sub par fuel system, this one might surprise you. I've ran engines on the dyno way back when we used the Holley mechanical pumps on the engine with alky. Motor just didn't make the power I thought it should so I used the dyno's electrical fuel pump system and the engine gained 30+ HP. It was running out of fuel with the mechanical and you couldn't here it. I was having issues with the fuel meter so I wasn't getting fuel numbers (this was back before the wide band O2 sensors was popular to get A/F readings) So I wasn't getting A/F readings and if I had I would have seen it but you couldn't here it at all on the dyno and sounded fine.


Head CFM per HP possibility is actually more like 2.5HP per CFM flow, but that is with a high end engine as a general rule 2 to 2.35 is close for an average race engine potential. Way back in late 90's the weld tech 18 degree head flowed 344 and on a 358 guys made 760 to 780 which is in that 2.2 to 2.3 range. Also keep in mind Air flow isn't the end all, it's air speed and cross section and a number of other things. You can make more power with a head that flows less a lot of times, so be careful with flow numbers alone. If you need a read/info on that stuff look for Darin Moran articles or his posts on some forums.

If you look at HP per cubic inch: again varies but the most elite of elite naturally aspirated barely makes 3HP per cubic inch and that's a drag pro stock engine. A cup engine has never gotten close to 3. A basic guide line is 2 per cube is pretty good and 2.5 per inch is dam good for a circle track type engine and likely a small CID and extreme RPM deal. Most of your large CID LM stuff is in the 2 to 2.2 range.

Rear wheel dyno's vary a lot as well as engine dyno's, but you should see around 15% loss with a bert/brinn and a Q/C to the rear tires.

Hope that helps!

[fastford]

Jack Cornett put ford on the map when it comes to dirt late models in the 90,s , along with bloomer.......

[billetbirdcage]

Krom, here is a couple of articles you may find interesting and worth a read.

https://www.enginelabs.com/engine-tech/project-spinal-tap-ii-the-valvetrain-dynamics-of-11000-rpm/

This next one more shows some of the newer stuff being done on the elite type engines with cam core and lifter sizes, bore spacing and etc.

https://www.enginelabs.com/engine-tech/the-equal-8-inside-dan-jesels-new-clean-sheet-12000-rpm-v8/

Anyways figured you might like them.

[Kromulous]

Whoa, a lot to take in there, great articles !

Gonna take a while to crunch all that info. I was running the numbers on our engine, with those formulas, and its really close.

I was also reading about ports, and how some will "choke" if there not designed properly. I think it was a Vizard article.

That Jesel-8 i bet is a beast !