CID/RPM/CFM/HP

[novadude]

My tests on stock un molested 062 GM vortecs is 228 cfm @28" (more than one set tested)

My current self ported GM 062's with Manley 2.02 x 1.60's are right at 250-255cfm @28"
I did not do a MAX race full effort on them.

Yup Randy is pretty sharp no doubt but he does not do himself any favors. Sometimes.

i should have kept my old Nova like Randy's.. a great car for Drag Racing.

"My tests on stock un molested 062 GM vortecs is 228 cfm @28" (more than one set tested)"


That's exactly what I've seen, although I did have one go 240 one time factory stock, but I did not test every port. I'm a big fan of Randy and his kid.

As an additional data point for stock out-of-the-box 062 heads with factory valves and valve job, here are my flow numbers:

Lift Flow
.050 44.9
.100 76.6
.150 105.6
.200 135.8
.250 166.8
.300 189.8
.350 210.0
.400 227.2
.450 230.6
.500 227.8

Pretty much in-line with what everyone else has already said.

[skinny z]

Not knowing your exact cam specs., I think I am pretty close where the horsepower @ rpms will peak, yep.

At this point in time, I don't know them either. Some of it depends on the limitations of the heads and the resulting RPM range I should target. If 5500 is the limit, then that moves my choice in one direction. If 6200 is possible, then my choice will move in another.
All things considered, I was making peak power with the 355 in or around 5500-5700 and while performance was adequate for what I was doing, the combination didn't work as well as it could have at the drag strip. I had mentioned earlier that I didn't want to turn this thread into a "build a drag car this way" deal, but I will say that with the additional torque and HP of the added cubes, if nothing else, it should help my 60' time and lift my trap speed somewhat. The gearing will be more appropriate then.

[skinny z]

As an additional data point for stock out-of-the-box 062 heads with factory valves and valve job, here are my flow numbers:

Lift Flow
.050 44.9
.100 76.6
.150 105.6
.200 135.8
.250 166.8
.300 189.8
.350 210.0
.400 227.2
.450 230.6
.500 227.8

Pretty much in-line with what everyone else has already said.

I've got a little something on the Vortecs at least. Although from the looks of it, I'm missing the arguably strongest point of the OEM head and that's the flow from .050" -.200".

Flow.jpg

Tests done with a 4.030" fixture bore.

[randy331]

Your worrying too much about CFM, but just CFM wise you have enough to make 500 HP, but you really should be looking for, how to optimize and improve what you have to run the goal you have, with the budget you have.

A 383 will make more HP/CFM than the same heads/intake and cam will on a 355, but it will be less HP/cubic inches.
It will also make it at a lower RPM which will most likely be a plus on a less than optimized street car.

Randy

[skinny z]

I appreciate all of the input from everyone.
I've been down this road a few times and have generally kept things on the conservative side. I think my favourite was a stock Vortec headed 353 with 10:1 (measured) and Comps XR276HR (w/ 1.6 RR). Despite a crippling exhaust, it was an everyday mid 12 second car (at nearly 3700 lbs) and knocked down well over 20 mpg (carbureted). I changed things up after that and have been living with this latest combination (the RHS heads, 10.2:1 and the XR288) but never got it out to test. By all accounts it felt quicker and it did get the best highway mileage of any SBC I've owned (I'm big on MPG) but the shortblock, I'm pretty sure is toast. As I had mentioned, I don't feel the package was optimized. At 10.2:1, the cam installed on a 106 ICL produced a DCR of 7.8:1. Moving it up to 102 ICL brought it up to 8.0:1 but that was more or less a crutch for the lack of compression. That's basically a non-issue now.
So that brings me here and my asking the questions of the original post.
Now that the theoretical is out of the way (for the most part anyway), I'll to concentrate on the rest. Seeing as I have most everything else, really all that's left is a camshaft.

[F-BIRD'88]

Look at the 1/4 mile MPH not the ET to see how much power you are making.

Look at the real MPH from real time slips (in Edmonton) not corrected MPH....unless this is just a dream exercise .

.

The purpose of moving the cam is to see if it helps car acceleration. The theoretical or even actual cranking
compression test means nothing to the end goal.

its nice to dream

[skinny z]

Look at the real MPH from real time slips (in Edmonton) not corrected MPH....unless this is just a dream exercise .
its nice to dream

I think you're missing something regarding corrected MPH and ET.
What if, for example I have a personal best of 12.64 @ 106.82.
Later that month, same car, different track goes 12.92 @ 104.87.
What am I to do? Re-tune?
However looking at the corrected data: First time slip corrects to 12.46 @ 108.38. Second time slips corrects to 12.48 @ 108.65.
Re-tuning wasn't necessary. The car ran what it was capable of given the DA of the day.
That's why I'll "dream" and keep a record of corrected ET and MPH.
For the record the DA for the 1st slip was 1321. The DA of the 2nd slip was 2855.

You will never operate under these conditions.

I have in fact operated at altitude densities of 150' below sea level.

Going from 660ft actual elevation to sea level at a sea level track or the equal of (density)... will not result in 2 tenths ET.

I'll give you that. 1300 ft is worth about 2/10ths and 3000 ft is about a half a second. The MPH goes up proportionally as well. That would follow your logic regarding trap speed vs HP. More horsepower nets greater trap speed. Better air equals more horsepower. Better air, more trap speed.
I'm looking forward to racing on the coast next season. I just hope it's a nice cool dry evening...

[vortecpro]

Look at the real MPH from real time slips (in Edmonton) not corrected MPH....unless this is just a dream exercise .
its nice to dream

I think you're missing something regarding corrected MPH and ET.
What if, for example I have a personal best of 12.64 @ 106.82.
Later that month, same car, different track goes 12.92 @ 104.87.
What am I to do? Re-tune?
However looking at the corrected data: First time slip corrects to 12.46 @ 108.38. Second time slips corrects to 12.48 @ 108.65.
Re-tuning wasn't necessary. The car ran what it was capable of given the DA of the day.
That's why I'll "dream" and keep a record of corrected ET and MPH.
For the record the DA for the 1st slip was 1321. The DA of the 2nd slip was 2855.

You will never operate under these conditions.

I have in fact operated at altitude densities of 150' below sea level.

Going from 660ft actual elevation to sea level at a sea level track or the equal of (density)... will not result in 2 tenths ET.

I'll give you that. 1300 ft is worth about 2/10ths and 3000 ft is about a half a second. The MPH goes up proportionally as well. That would follow your logic regarding trap speed vs HP. More horsepower nets greater trap speed. Better air equals more horsepower. Better air, more trap speed.
I'm looking forward to racing on the coast next season. I just hope it's a nice cool dry evening...

1320 divided by 106.82 = 12.35
1320 divided by 104.87 = 12.58
1320 divided by 108.38 = 12.17
And this is only a jumping off point you can do much better


The DA does not matter here, talking about cylinder heads is one thing, in my opinion the main focus should be learning how to make the rolling car work, because you are not utilizing your HP, just advice.

[skinny z]

1320 divided by 106.82 = 12.35
1320 divided by 104.87 = 12.58
1320 divided by 108.38 = 12.17
And this is only a jumping off point you can do much better
The DA does not matter here, talking about cylinder heads is one thing, in my opinion the main focus should be learning how to make the rolling car work, because you are not utilizing your HP, just advice.

I understand that. And thanks for the interesting breakdown.
Yes. This was about making HP with small heads however the topic veered off a little and I was demonstrating my affinity for the correction factors. Then I it turned it into my vehicles performance which at the start, I had deliberately avoided so as not cloud the issue as I've manged to do here.
I'll be the first to admit that this is not a drag car. It's just a car I take to the drag strip. Typically I'm mostly interested in the MPH as it reflects what I enjoy most about cars and that's engines and engine performance. It's ET however that catches most people's attention. I've an 11 second street car. The new Demon runs 9's. And so on.
That said, even with the older engine, not this current 355 with the ported heads and 288 but rather the out of the box RHS Vortec heads with a custom roller of 274 degrees version, it still made some steam. It has gone an uncorrected 107.65. And as you point out, "learning how to make the rolling car work" with a better converter, some gearing and decent traction it would be a low 12 second car (there's that ET reference again) and the jump to 11's would be a simple step involving a 385. Maybe even with the untested 355 that's going to be laid to rest (maybe).
Anyway, all of this is appreciated. And thanks again.
As far as the heads and 385, I've got some work to do before moving too far along with it. Mainly determining the cost effectiveness of reusing the old block and getting a reciprocating assembly or buying a complete shortblock altogether. It might even be that if the 355 isn't too wasted, perhaps a re-ring and re-bearing (and possibly a better spec cam) will be the order of the day.
Maybe that's a subject for another thread.

[F-BIRD'88]

This car is a Street cruiser. It will nevrr get close to running at that chassis eficietcy..

It will never see A 1320 factor..

More likr 1360 to 1380.

That is about as good as it will do without gears and converter and drag car setup.

You can see what this cars factor is by looking at the real et and mph from his time slips.

Not corrected data... Real actual warts and all.
This eill tell the tale of hat this car is going to do with more power.

eg: 1360 to a 1380 factor
11.90 et goal on all street cruiser trim

1380 ÷ 11.90 = 116 mph

1360 ÷11.90 = 114.3 mph.

This is not a drag car and he won't make it be...
It will never show a 1320 factor..

If he would post the real car data not corrected bs
i can show real close what to expect with the new power but same car.
It is going to need a 116 to 118 mph to get in the 11's.

In that car,, in Edmonton not 150' below sea level.


ha ha.... keep it real.

1360

[cgarb]

My car is a 1313 factor...10.26@128mph. I bet a good many stock and superstock cars can beat a 1313 factor. That is pretty cool to think about though.

[skinny z]

This is not a drag car and he won't make it be...

You might be right. But I miss your point entirely.

If he would post the real car data not corrected bs...

He did.

[F-BIRD'88]

I get the best car anylisis with the complete data from some
actual time slips of THAT CAR . Uncorrected....
true right from the time slips....

It does not matter if the previous or current motor is or was
less powerful than the new plannedm motor is..

This ain't Randy's Nova.... Nor your drag car...

It is a inefficient "street cruiser" And in Edmonton you ain't
runnin at sea level....

"well I would have beat you if we were at sea level"

[skinny z]

I get the best car anylisis with the complete data from some
actual time slips of THAT CAR . Uncorrected....
true right from the time slips....

Uh, I'm not looking for analysis here.
Perhaps another thread? But this isn't the place.
This was about small heads and 385 CID. It still is actually. Nothing more. Until I opened my big mouth and got it all turned around.
I'm sure you understand.
Thanks just the same.
With any luck, I'll post here again with either the old engine refreshed or a 385, or maybe even a supercharged LS. Then I'll invite the locals for some introspection (as it pertains to my car that is).

[F-BIRD'88]

Why don't you just do it right the first time and supercharge your 355?
You will SPEND A LOT less money. and actually hit reliable 11 sec et's in that car.
And only have to do it once .

How many motors are you going to build? 3-4....