I used to think the same thing until I was informed otherwise.

This guy has thousands of sbf combinations using all different parts...he basically knows exactly what parts do what on whatever you're building.

They can be modified as much as anyone says they are but they still don't flow worth of squat compared to a 205/225cc head with 2.08" intake valves.

 

I agree and I disagree.

Tourqe is a function of displacement. It doesn't matter if the displacement comes from increased bore diameter or increased stroke. Two motors of the same displacement and numerical rod ratio, but one has a big bore and short stroke, and the other a long stroke and a small bore, will both make the same tourqe, all else but the bore and stroke being equal. A larger bore can better support large valve areas too.

I do agree that the horsepower potential is mostly the result of the airflow capabilities, and improved airflow potential may actually improve tourqe though out. Larger valves and larger ports don't kill low end on "large displacement" motors. They usually improve tourqe through out, just as long as the engine is large enough to swallow the air.

The 185's work fine on 351 based strokers for street use by my experiance. Now a race motor may want more, but for an everyday street high performance stroker, I think the 185's are plenty. The TFS R heads would also be plenty, IMO.

Too much cross section can be detrimental if it's not done right. It can and sometimes does, kill the port velocities. I know of a case of hogged out GT40 heads on a 351w, only making 160HP on a chassis dyno. Really.

I also know of a few 408 strokers making more than 700Hp with carefully ported Canfield heads, flowing well in excess of 300cfm.

 

I will dig up some information that may change your mind, I'll be back tomorrow.

 

Meanwhile, back on the ranch...........I'm driving around in my 393 with all the wrong parts, just as happy as a lark.

 

good for you, im glad youre happy :-) after all thats the important part- that youre happy with what you have, and that you didnt have to spend 3 times as much for race parts that would only make you disappointed because you spent 3 times as much for doing the same job, even if it would do the job a little faster, after all if you really wanted power you could have just swapped in a 460 and c-6, and with some exhaust port work, heads shaved a bit, headers, rv cam, and aftermarket timing chain set straight up- had some real power

 

Why didn't I think of that?

 

probably because youre in the small block forum and already had the small block, and wanted to make do with what you had... but hey- its too late now- money is already spent... oh well- next time you can go big block... im sure you wont want to go back to a small block after you feel 460 cubes... or even better a 545 ci like im building

 

i just come in here to try to decide how to build the 302 going into my maverick and my other 302 going into my pinto, and ask people why they didnt go with a 460 for their truck, because after all thats what theyre made for... small blocks are for light vehicles revving fast and high, big blocks are for trucks or for those that simply have to have fuel injection- small blocks are totally the way to go and you can work around small displacement by doing a stroker. but anyone building a carb truck- big block all the way!

 

Oh come on now, not once did I say you had the wrong parts. Apparently I am being misunderstood because SEVERAL times I have stated in this thread that you got what you wanted and it was cheap and you're happy and therefore all the more power to ya.

Another time in this thread I said that my point here was to simply say a couple things...

1. Your engine does not make anywhere near 400hp as someone else thought it would, and a touch on why that is.

2. That your goal was attained for short money =

3. bring up the topic for discussion that what you bought was not optimal for building the most low end power you can get (which A LOT of people think is what you did).

I knew it would be difficult to explain to someone that what they believe is not necessarily true in the real world, but I think most of the confusion is in the misinterpretation of what I am saying (hard to do over the internet).

The tq of the engine is mainly determined by the stroke. It has the leverage on the crank and here is a list of typical RWTQ numbers for different sized SBF's....

RWTQ should be at or greater through a manual tranny...

330rwtq for a 302-306
370rwtq for a 331
390 rwtq for a 347
390 rwtq for a 351
430 rwtq for a 373
460 rwtq for a 393
480 rwtq for a 408
500 rwtq for a 427
510 rwtq for a 434


This is with an optimized combination, give or take.

With that being said...

At this point I am hesitant to believe warwagon's 393 makes 400ft-lbs...as we don't know what it makes because he hasn't dyno'd it.

I've gone through a similar situation to what I am explaining because the first time around when I did my 393 it made only 220hp/330tq. I know why, not worth getting into...but I'm giving numbers and explaining that I have been through one of these builds before.


Now I will be paraphrasing some information directly from a cam designer Jay Allen. He has worked with 1000s of sbf combinations and knows what parts are out there...what does what...and so on. His living is based on his company Camshaft Innovations, which makes custom camshafts for optimizing combinations, rather than using an off the shelf cam that isn't right for whoever's particular engine.


*This is all within the context from Jay surrounding heavy truck motors not racing engines.

A 393 has a 3.85" stroke which is almost the size of a big block chevy and is about the size of a 460 ford. The stroke of the engine determines the volume in the cylinder head needed. The CFM of the head will tell you it's power capability. Warwagon's motor probably makes between 350-400ft-lbs of tq, which is a possible indication of the fact that the CFM is low and therefore the power is low (for what it could be).

direct quote "The people that think you need a small head for *velocity* and *torque* are the people who need NOT to be selling engine parts. Those are old school myths. You'll hear the *internet experts* chime in and tell you the heads are ok. The people that tell you this...ask them when have THEY actually built one for YOUR application. They'll shut up at that point or give you a bunch of worthless rhetoric."

This was in the context of the head being an AFR185 on a 408...in which he says are too small.

Here is some math he gave...

Lets take a 393 with a 185cc AFR head (much larger than the 69 351 heads warwagon is using).

393/185 = 2.12 cid per cc in the head

Thus...

347ci/2.12 = 163cc of head
302ci/2.12 = 142cc of head

"If I built a 347 SBF and I put a set of GT-40 heads on it, would I make good power? No.

If I had a STOCK 302 with STOCK heads on it and I did JUST a valve job, would I make good power? No.

Now head volume by itself is almost meaningless. But for argumentive purposes only. I use the Canfield 195cc heads on a 347 anyday, all day, everyday, and they kick butt."

347 / 195 = 1.78 cid per cc in the head.

393 / 1.78 = 220cc cylinder head.

Does that make any sense?

I posted it just for observation for ya.

I have seen Jay on many occasions state that larger components DO NOT kill low end power like people think, and if anyone knows that it would be him.

A lot of what I am saying is from Jay, I am no expert and do not claim to be...I am simply talking about this for the sake of discussion and learning.

To repeat myself for about the 3rd or 4th time.....am I saying warwagon did anything wrong or needs to change anything? no I am not.

Am I saying that he could of made more power than he did...yes...easily...but it would cost more and I don't think that is what he wants.

But it is common to see this low RPM RV style stuff for people looking to make lots of low end power...but they are doing it for the wrong reasons. They think they are making the most tq when they are not...in fact...they arn't by a long shot.

IF you wanted to spend more money...and you spent about 2-3 grand on a better top end...not only would you of made more low end tq and power...but you'd of made a @#%^ load more hp and tq overall (peak) and blown the doors off what you have now.

If you think your happy now...think of that same motor with 1/3rd more power. That's one of those things that does in a big way. But, again, it does what you want and it's 1500-3 grand cheaper...

 

I think I can do this more concisely. What your basically saying is that a larger engine can handle a larger intake port cross section, with your diplacement to runner volume ratio examples. This we can all agree with, as it pefectly logical. Since the swept volume in the cylinder is greater, the increase in port volume will not reduce the velocity of the flow.

There's a problem with the examples of greater tourqe being the function of greater stroke, because the displacement is also greater. Are the gains because of leverage, or the displacement?

Compare the tourqe of the 427FE to the 428FE. Both engines have the same tourqe output, although the 428 has more stroke. Another interesting comparison is to compare a 7 liter FE to a 427 Windsor stroker. The tourqe output will also be about the same ( As I recall the FE still had slightly more Tq, despite less stroke), but the FE will usually beat the Windsor in HP unless the heads on the Windsor can flow in excess of 300 cfm.

Any extra "leverage" that a stroker may have is actually very marginal. For example, a 347 has .4" more "stroke" than a 302, but the actual increase in "throw" is only .2". It would only be .12" in a 331. This could provide a marginal increase in leverage theoretically, but the rod that is providing the force behind the leverage is at a less optimal angle. The rod angle, at 90* crank rotation of the 302, is ~17*. On a 347 it is ~ 20+*. The theoretical advantage gained is lost, by the reduced rod ratio.

However, the total volume of air being pumped is greater, and it comes through the intake ports at a greater velocity at lower RPMs, all else being equal. This proves that it's mostly about airflow and air volume dynamics, not so much about crank leverage, and it also proves your argument that bigger airflow parts will work fine on bigger engines.

 

I agree on larger parts making more power and torque on a larger displacement engine. But it would still shift his power and torque curves up to a higher rpm. I know through my own experience that it wouldn't have bottom end torque that he has now with 205/225 afr's and a 2.08 intake valve and such. I have a '00 Mustang GT that I've put on ported stage 2 heads with bigger valves, ported intake, all the normal stuff to try and make a killer 4.6 2V engine. It doesn't make near the power and torque under 4000 as the stock engine and I even left the stock cams in it that had a pretty low duration from the factory. If I put the bigger cams in it to match the airflow of the heads its gonna shift my powerband up even higher, of course thats what I want in the stang, but not in a truck. For WarWagons rpm range, his usage for the truck, and his combination, I would say he's dead on. His motor is getting plenty of air. His carburetor , 525 cfm, is actually bigger than what Holley recommends on a 393 cubic inch engine with a max 4000 rpm range. Holley recommends a 470 to 570cfm vacuum secondary carb on his engine.

 

I'm givin' up on this one.

 

from my take on this,say his engine peaks at 375 lbs/tq at 3500.with some better heads/cam his PEAK would move up to say 475 at 4500.at 3500 the engine would be well over 400 lbs/tq.so it would make more torque at the same rpm as the smaller combo but peak at more at a higher rpm.

i think this is what mustanggt221 is trying to get across.

rollinhi95-i think comparing a 4.6 to a windsor is like comparing an apple to a cheese pizza.4.6's are torque defficient to start with,so any work to increase the power on these engines will move the power up.

 

Thanks for trying to help.

Rollinhi95, you can't say "I know through my own experience that it wouldn't have bottom end torque that he has now with 205/225 afr's and a 2.08 intake valve and such"....because you've never done it and don't have the experience to say so.

When I talked about useless rhetoric....thats exactly what you brought to the table when you're talking about your 4.6. Like I said, I'm no expert and don't claim to be, most of my information is coming from Jay (who has 10 times the experience of any of us). My guess on why your engine had that result is because you used the stock camshafts.

When you build a stroked windsor with a huge top end, you can either make it have all its power up top or save some of that bottom end by using an appropriate camshaft. In all likelyhood, there is no off-the-shelf cam for this type of stuff...and there usually isn't when it comes to custom engine building. When you use huge top end parts and still want low end...you've gotta use a camshaft that will make that happen. It's the key component here, not velocity and small port bullcrap. The right camshaft is what'll make it work and have that low end still. My guess is that if you didn't use the stock camshafts, and used different camshafts intended to keep low end tq, than you'd still have it. (but you wouldn't do that because it's a mustang not a truck)


Yes the motor I speak of would make more top end power...OF COARSE it would...BUT my point is that at RPM for RPM (pound for pound) it would still make the same or better power over warwagon's...


bronco521's first statement is what I'm talking about.

The bigger parts will push the peaks up further in the RPM range...but that doesn't mean you're just moving it. Your CHANGING it...you move the peaks higher in the RPM range but your still gaining power down low.

The bottom line here is this...if you want the most low RPM torque...building a low rpm RV style engine like warwagons is not the way to do it. This may be hard to believe, as it goes against most common belief, but the real way to make the most low end tq in this senario is to use those huge top end parts and have a custom cam that taylors the power the way it is desired.

If you had warwagons 393 on a dyno vs another 393 with 225 afrs and the appropriate cam/intake/exhaust...

The bigger 393 would make more tq at 2000 rpm...it would make more tq at all RPMs. Even though you'd have a peak tq at about 4500 rpm and be able to rev it to 6500...doesn't mean there isn't anything down low...in fact...there would be more than warwagons down low.

Interesting, isn't it?

It's a simple fact...the bigger top end would blow the doors off warwagons combination...can you really imagine 500hp/500+ tq out of the same cubes that warwagon is getting...what...250hp/350 or so tq? Thats a rediculous difference...

It will be hard to get it out of your head that you won't loose that low end power....but according to Jay...it's a myth and he proves the contrary every week by making camshafts for these motors.

 

Don't tell me whether I have experience or not, or I have never done it. You wouldn't know. I'm not just on here blowing wind to heat up an argument. This is what I do, I build motors, I drag race. Of course I don't have the experience of this guy your talking about, but I know what I done, and what I've seen. For the sake of getting banned or starting a flame war, I'll just take my experience and my honest opinions somewhere else.