Interesting article in MM&FF this month

[NIKwoaC]

Some of you guys know that I'm a proponent of the "big head/small engine" argument, and this month there was an actually good article in MM&FF about just that.

I know magazine articles have to be taken with a grain of salt, but I thought this one was noteworthy, and I figured a few of you guys would get a kick out of it.

If you haven't already flipped through it, MM&FF ran four different cylinder heads on two engines, a 302/306 and a 302/363. The cylinder heads were all Dart Pro 1 units, in flavors of 170 and 195 (as-cast) and 210 and 225 (CNC). According to the article, the 225s peak flow at 325CFM.

All variables were held constant across the tests for either engine, like compression, cam, intake, etc.

Long story short, they managed to blow the 302 up before they could test the 170s (WTF!?), but they did test all the others. Oddly enough, they cut the 302 off at 6200 RPM for the tests (again, WTF!?) which is frustrating, but I think the test data is clear enough for what it is.

Bottom line, the three heads tested on the 302 made damn near identical power numbers from the start of the test (2800 RPM) up to 6000 RPM, where the 195s seemed to run out of air. Both the 210s and the 225s continued to post growing numbers up to the test cutoff at 6200. Both were 399 HP at 6200 RPM, and I'm sure they would have made well over 400 if they would have spun the engine further, but that's not the point. The point is that the low RPM power/torque numbers were unhurt by the "huge" heads.

They revved the 363 up to 7K, and it did exactly what you'd think it might. Same story, really. The bigger the head, the more power it made.

Thoughts?

 

[Notchbck93]

My only argument may be that the the air "may have become" lazy around town in part throttle situations running bigger heads. Resulting in an engine that doesn't as frisky around town as one has come to expect with VVT.

 

[NIKwoaC]

My only argument may be that the the air "may have become" lazy around town in part throttle situations running bigger heads. Resulting in an engine that doesn't as frisky around town as one has come to expect with VVT.

The author actually makes a comment along those lines in the article.

There's no evidence to support that argument wither way, as it's kind of subjective to begin with. What is part throttle? How do you measure part throttle performance? Is ANY engine really designed for performance at part throttle?

What I will say is this: You don't drag race at part throttle, and when I'm on the street, I don't want my car making 400hp when I'm at part throttle.

 

[BK_CAULEY]

My heads flow 325i 290e @ .050 and i have them on a stock bottom end with a stock cam. just saying.

 

[stykthyn]

You still have the p heads?

 

[BK_CAULEY]

You still have the p heads?

lol. negative there speed racer.. Got a good deal on a set of TEA race ported twisted wedges. they where specifically ported for a turbo application. i actually had to do alot of work to get my header primaries to line up and had to dremel the hell out of some copper gaskets to clear the exhaust ports. they started life as 205's and after another $1100 worth of valve work and porting they flow 344i and 295e at max lift( .70)

Edit: picture sent.

 

[stykthyn]

Was about to ask where the water jackets went....

 

[5.0Torx]

post the link. id like to read it if its online

 

[mob]

Why would this debate even exist? What exactly is "too much air". As long as you have enough fuel, the more air the better.

 

[NIKwoaC]

lol. negative there speed racer.. Got a good deal on a set of TEA race ported twisted wedges. they where specifically ported for a turbo application. i actually had to do alot of work to get my header primaries to line up and had to dremel the hell out of some copper gaskets to clear the exhaust ports. they started life as 205's and after another $1100 worth of valve work and porting they flow 344i and 295e at max lift( .70)

Edit: picture sent.

Badass! PM me pics too, or even better, post them up in this thread. I'm building up the 'ol 302 this winter and I'm looking at possibly doing 205s myself, or maybe a TEA warmed up set of FAC 190s.

post the link. id like to read it if its online

No can do, it's this month's article, which means it won't be online until next month.

Why would this debate even exist? What exactly is "too much air". As long as you have enough fuel, the more air the better.

There are still a good deal of people who hang on to the idea that you have to maintain "velocity" in order to have drivability or "torque down low". These people claim that big heads kill "velocity". I use quotation marks because these terms get used loosely. Very loosely.

 

[Venom351R]

I have not read the article yet but I do have the issue. Considering that strapping on 205's to a 302 is acceptable I dont have much issue now putting 240cc High ports on my 351

 

[skunk21]

Some of you guys know that I'm a proponent of the "big head/small engine" argument, and this month there was an actually good article in MM&FF about just that.

I know magazine articles have to be taken with a grain of salt, but I thought this one was noteworthy, and I figured a few of you guys would get a kick out of it.

If you haven't already flipped through it, MM&FF ran four different cylinder heads on two engines, a 302/306 and a 302/363. The cylinder heads were all Dart Pro 1 units, in flavors of 170 and 195 (as-cast) and 210 and 225 (CNC). According to the article, the 225s peak flow at 325CFM.

All variables were held constant across the tests for either engine, like compression, cam, intake, etc.

Long story short, they managed to blow the 302 up before they could test the 170s (WTF!?), but they did test all the others. Oddly enough, they cut the 302 off at 6200 RPM for the tests (again, WTF!?) which is frustrating, but I think the test data is clear enough for what it is.

Bottom line, the three heads tested on the 302 made damn near identical power numbers from the start of the test (2800 RPM) up to 6000 RPM, where the 195s seemed to run out of air. Both the 210s and the 225s continued to post growing numbers up to the test cutoff at 6200. Both were 399 HP at 6200 RPM, and I'm sure they would have made well over 400 if they would have spun the engine further, but that's not the point. The point is that the low RPM power/torque numbers were unhurt by the "huge" heads.

They revved the 363 up to 7K, and it did exactly what you'd think it might. Same story, really. The bigger the head, the more power it made.

Thoughts?

I read the article, pretty good. The large head theory works although the 210cc where pretty evenly matched with 225cc heads and really offered no power gains on the 302 they tested over the 210's. The 195cc heads are still a very good street head and on both motors had very good mid range hp, not hard to figure they would lose out on the upper end.

 

[NIKwoaC]

I read the article, pretty good. The large head theory works although the 210cc where pretty evenly matched with 225cc heads and really offered no power gains on the 302 they tested over the 210's. The 195cc heads are still a very good street head and on both motors had very good mid range hp, not hard to figure they would lose out on the upper end.

I think the 225s would have shown their worth if they would have spun the engine any higher than 6200.

But yea, it comes as no surprise that the bigger heads make more steam at high RPMs. What I'm really trying to point out is that the bigger heads did not give up any low RPM performance compared to the smaller heads, which is a common misconception.

 

[BK_CAULEY]

I make decent power down low. nothing to freak out about. but when boost hits its very nice.

 

[NIKwoaC]

I make decent power down low. nothing to freak out about. but when boost hits its very nice.

Do you have a progress thread or something for this car? I had no idea you had a turbo car. Last I heard you sold the 351 swap coupe...?

Also, you gonna post pics of them heads or what?

 

[90lxcoupe]

My only argument may be that the the air "may have become" lazy around town in part throttle situations running bigger heads. Resulting in an engine that doesn't as frisky around town as one has come to expect with VVT.

I dunno what VVT is, but my motor with "big" heads on it is about as frisky as i felt the first time i saw baywatch at 13 years old.... Theres no reason not to go big. and if it feels lazy, slap a blower on it...

 

[GTA_V6_Mustang]

I dunno what VVT is, but my motor with "big" heads on it is about as frisky as i felt the first time i saw baywatch at 13 years old.... Theres no reason not to go big. and if it feels lazy, slap a blower on it...

Variable Valve Timing

I would love to see what we could do on the new 5.0 with a combo of VVT and MultiAir. You would never need to change cams again.

 

[BK_CAULEY]

Do you have a progress thread or something for this car? I had no idea you had a turbo car. Last I heard you sold the 351 swap coupe...?

Also, you gonna post pics of them heads or what?

No i dont have a thread on it. And yes i did sell the coupe. Ive had this car for a while now. and i will get some pics up here in a little bit.

 

[Notchbck93]

The author actually makes a comment along those lines in the article.

There's no evidence to support that argument wither way, as it's kind of subjective to begin with. What is part throttle? How do you measure part throttle performance? Is ANY engine really designed for performance at part throttle?

What I will say is this: You don't drag race at part throttle, and when I'm on the street, I don't want my car making 400hp when I'm at part throttle.

Thinking in terms of a 2v 4.6, it seems that just about every mod takes from the bottom and adds to the top...solution is to regear.

I'm impressed that WOT hasn't given up anything down low on this pushrod set up, but I would still like to see a test on 1/4 power.

1/4 throttle certainly is measurable. In thinking of terms of 360 degrees and using a 180 start point, we know that half of 180 is 90 and half of that is 45 so you could say that 225 is the start point of the test. Take a TPS reading at that given point and when you do a dyno pull just keep it cracked at the 225 degrees. Of course, I don't believe any real measurements are ever taken below 2500 are they? This is the area that most people spend the most time in on the street.

Maybe a blind test like GM performed on the pushrod vs quad cam debate.

Throw two 302 set ups on two fresh rebuilds in two equal Foxes. A classic Cobra build with some thumper heads, Cobra/Xploder/GT40 style intake, and a Cobra style cam and then take another 302 with some 225's, a RPM II intake or victor and a cam to support the heads and intake. Pistons would have to be fly cut on the bigger cam/head set up of course.

Have them do a classic road and track review and see which one would be more enjoyable as a cruiser.

I would put money on the milder combo to be more "street friendly."


Now, seeing that I can't read the article yet, Did they simply swap cylinder heads and leave the same restrictive intake on?

 

[90lxcoupe]

Street friendly is a very loose term and my car with 205 heads and a decent sized cam is just as street friendly as my old gt40x/ecam combo.

I think they used a funnel web for the test.