Id probobly only run a 600-650 holley vaccume secondary but no more than that.

 

I was at WR #5 the other day. I must have missed it.

 

Yeah no doubt, AFR 185s and a slick intake would make great power! What do you have in the exhaust department? Get a custom grind cam if you can, they are a few hundred but make a massive difference from what they say.

 

185s I've been told are still too small....mainly for their cross section.

Recommended crosssection is over 2.5.

So 205/225s would be more appropriate.

 

Sounds like there is only one way to build a motor. Therefore I'd better call Comp Cams and let them know that they just need to reduce there inventory to one cam. I'm sure they will be glad to hear that. It will save them a lot of money.

 

If you're trying to say I am suggesting there is only 1 way to build a motor than you are incorrect.

Several times I've stated that your motor seems to be a good fit for your needs.

My simple point is that it's choking that many cubes and there is a TON of potential available...doesn't necessarily mean it's for you or that I am telling you you need to change anything.

My interest here is discussion and education.

My point is that larger induction will produce substancially more power with no side effect in low end power.

Optimal for that size engine is significantly larger induction components. Optimal gets you the most power and efficency.

Optimal costs a fortune.

 

Optimal is the key word here. This motor was built with one thing in mind......more torque for a minimum of cash. Compomises are surely to follow. Bigger is better to a point. Cam selection is the key to any build. Running a cam that torque peaks at 5000 makes little sense on a motor that will never see 5K. Even if the combo makes more torque at 3000 that my combo..........it won't be as throttle responsive, nor very economical, nor cheap to build. I believe we did well with the money spent. The dyno will tell the tale.

 

Was this a 5.0L or 5.8L based stroker?

 

5.0's only go to about 355ci's...5.8s can go to 427s.

A 393 is a 3.85" stroker crank, stock 351 rods, and stock 302 pistons, based on a 351 block.


I've said it many times in this thread that what you did seemed to be right for you.

Bigger is always better in this situation, the bigger the heads you can put on there the more power you'll make.

Cam selection is critical in ANY motor. But also important is the selection of head, intake, and exhaust to compliament eachother and make for a nice match of components.

I don't see how you can say your motor would have more throttle response.

You've said that a cam to a peak of 5000 rpm is no good on a motor that will never see it....well...in actuality...that cam would be appropriate if the rest of the components were up to the same task. If your head, intake, and exhaust combination doesn't work over 4000 rpm and you've got a 5000 cam (trying to keep it simple) than you've got a mismatch and the cam would be wrong.

There is no reason not to use larger components other than budget. The larger components will make more power at all RPMs and be more efficent.


Look at 408bronco's combination, something like 300hp and 400tq...but got like 8-9 mpg. He has some incorrect parts on it and choked it....it is a very inefficent engine, one that makes more power will do better on gas mileage because it will be more efficient.

 

If he ran larger port heads, larger valves, and all that stuff its gonna shift his horsepower and torque curves up higher in rpm's. The bigger heads and valves will kill bottom end torque. Smaller ports and valves speed up the velocity so you get that great throttle response off idle. No harder than he's cranking his motor its getting plenty of air, probably maxed out, but I doubt its starving for it. Now if he wanted to turn it up to 5500-6000 I can see your point for the bigger hot rod stuff.

 

That was my point way back in the beginning

 

Why is it so hard to understand this subject? Rollinhi95 hit the nail right on the head

 

I guess it's the old bigger is always better deal

 

This is the opposite of the point I've been trying to make.

This is an old wives tail...it does not reflect what happens in actuality.

Until you have put larger parts on it and verified via dyno...you have no evidence to suggest this.

I guarantee you if you do exactly what you say...it will NOT kill low end power...in fact...it will actually still increase power at the bottom end.

There is a quote from a particular cam designer who builds SBF combo's for his living...and his quote is "302 parts make 302 power"...

In other words, if you put 302 sized parts on a 393...it will make 302 level power.

Torque is a result of stroke...it is a given...if you have XX stroke you should get XX torque or more...provided the H/C/I/E parts are right. His horsepower is really really low and his tq is pretty low for the displacement. A 393 with a 3.85" stroke should make over 450ft-lbs easily...

These motors have outstanding tq outputs...with a tq band that is almost perfectly flat....about as flat as you get. A 393 with 205/225cc heads (that flow over 300 cfm per cylinder) along with the matching components...will make a tq peak around 5000 rpm and be able to rev to about 6500 but that doesn't mean you have to use it when you don't want to...and it doesn't mean that there is no power at low RPMs. A motor like this will make over 400 ft-lbs between 2k-6500 with a peak of about 500-550ft-lbs...your motor is said to barely make 400 peak. Not to mention the fact that this motor would have about 500+ hp that would rocket your truck to 13s or so in the 1/4mi. AND I bet it would be about the same in fuel consumption when driven similarly (except when nailing it). The reason? More efficient combustion.

What I've been trying to say here throughout this entire thread....is that bigger parts DON'T kill low end power, like many believe. His motor was cheap to build and it makes the power he wants.... but what I was looking to do was bring into the discussion the fact that IF he did go larger...it would be 10 times better than what he has. It would not only make about 100-150 more ft-lbs at peak...but it would have a better average tq and also more low end tq than what he has.

Those small parts don't make better low end tq than something with larger components. They actually make less power all around...but they're cheap.


And am I saying you need to change anything? No I'm not...

Just for the sake of discussion.

 

I guess we'll see what the dyno says. My objective was to get max torque right from idle to around 4000 max. The heads, combustion chamber and intake were major modified by a very knowlegable engine builder. I guess we'll see what I got for my money.