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You said:



The above statement of cannot be used on a 4” bore is not true. Just stating facts. No where did I say it was the ideal % of bore size. In fact it was only brought up in this thread because that is how the M311 is advertised to fit a minimum bore size of 4.00”. So while you may not suggest doing so GM and others can and have done that. GM for a 13 year run actually…






The above head would work on an LSX 427 provided the internals and valves were up to the power level and would also work on a 376 or 416 too.
 

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Discussion Starter · #62 ·
FWIW no one with any smarts builds a performance engine with a combination like that.

FWIW 2.165” / 4.00” equals 54% and shrouding will cause choked flow at peak valve lift with that cylinder head.

GM also attempted to use the 1 5/16 valve with the 283 CID back in 1961, having a 3 7/8ths bore, and it didn’t work then either. They quickly took the heads off the market. Next year, in 1962, they worked real well with the 327 CID, having a 4 inch bore.

—————————————————————————

-some physical examples-
434 CID engine.
2.165 inch intake valve.
4.155“ Bore
8,000 rpm
15* Intake valve angle

2.165” / 4.155” = 52% Ratio & equals ideal inline 2-Valve performance ratio.

Made 898 fwHP.
We built that engine over 12 years ago.

NHRA Pro Stock 500” cid.
2.555” Intake valve
4.750” Bore
8* Intake valve angle; means intake ports are virtually pointing straight up, not low entry level, as with what you proposed as being okay above.

Splayed valves, where both intake and exhaust valves are angled towards the center of the cylinder.

2.555” / 4.750= 53.8%, but with an 8° valve angle, splayed crossflow heads, also having a very shallow combustion chamber.

1500 fwHP from NA 500 cid on gasoline.

I am really surprised you would come out with that statement Matt.

You’ve seen me give that same information out here, many times before. This time though, I forgot to say they would bolt on, but not perform well.

Same issue with a 4.065 inch bore, and the 2.204 inch intake valve.
Here GM agrees, and use the 2.204” valve with a 4.125 inch bore.

They flow OK on the bench with the 4.065” bore though.

Head will bolt on OK.
But car won’t perform well at the track.

You know all that, and I wonder why you would make such
a statement on a performance forum like this?
Sir which combo are you referring to
 

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Discussion Starter · #64 ·

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You said:



The above statement of cannot be used on a 4” bore is not true. Just stating facts. No where did I say it was the ideal % of bore size. In fact it was only brought up in this thread because that is how the M311 is advertised to fit a minimum bore size of 4.00”. So while you may not suggest doing so GM and others can and have done that. GM for a 13 year run actually…






The above head would work on an LSX 427 provided the internals and valves were up to the power level and would also work on a 376 or 416 too.
You wrote:
"The above head would work on an LSX 427 provided the internals and valves were up to the power level and would also work on a 376 or 416 too."

Yes, since these heads have sufficiently large runner volume,
and flow very well, they are perfect for a 416 cid.

On this forum, regarding the stroked 416 cid engines, everyone
knew the larger engine needed more air.

But most, if not all forum members paid attention to the
valve to bore ratios, and did not put the 2.204" heads on them.

To the above, I state: Won't Work!

And to my knowledge, GM never put a 2.204" valve on an LS Engine, having a 4.065" bore.

---------------------------------------------------------------------

So Matt, Regarding Performance Engines. . .
When do we pay attention to these ratios, and when do we not?

---------------------------------------------------------------------

I like anyone else on this forum, can only pass on my experiences.

I'll stick with the ratios. . .

-my experience here-

Not paying attention to them, and trusting flow benches here does not work.
They don't tell the entire story.

Why?

The standard depression used on flow benches is 28" of water.
But 28" of water, only represents 1psi @ atmosphere.

So then, (14.7 * 28) amounts to 412 inches of water.

Generally speaking 28" of water represents the mean flow of an engine.

It is favored to use as the velocity on the bench, is about 50%
of the velocity seen in a live engine, making it easy for one
to convert bench velocity, to live engine velocity, in their head.

But peak flow is much higher, as the piston approaches
around 70° movement on the intake cycle. And air can
only reach a certain elasticity as it is pulled through, or
around tight spaces.

If the valve is to large for the chamber, and fits to close to
the chamber wall, it will not provide for adequate flow area
during peak flow demands.

And this is why forum members stayed away from bolting
on the larger 2.204" valve, on their 416's.

So again. . .
Won't Work!
 

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Discussion Starter · #67 ·
Got it
Its not. That tangent all stemmed from the comment where an M311 has a minimum bore size of 4.00” which is what at 6.0L has.


The engines you have looked at have all been over 4.065” bore.
 

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While not ideal there are many many performance engines based on a 6.0 block with a 2.165 valve head that perform well for the more budget minded and it does work ( A built G8 would be an example here or an LS2 with LS3 heads, both of which are common). I agree about putting a 2.20 valve LS7 head on a 4.065-4.070 bore, even GM did not think that would be useful. No need to muddy the thread up further with this though I did enjoy the segway into a 4.070 vs 2.20 valve from 4.00 and 2.165. The OP is looking at an LSX 427 and using M311 heads on it.
 

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While not ideal there are many many performance engines based on a 6.0 block with a 2.165 valve head that perform well for the more budget minded and it does work ( A built G8 would be an example here or an LS2 with LS3 heads, both of which are common). I agree about putting a 2.20 valve LS7 head on a 4.065-4.070 bore, even GM did not think that would be useful. A friend just installed a straight up race engine in his car that has a 53.7% ratio Int Valve/Bore, I'm guessing I should get him on the horn and tell him that won't work. No need to muddy the thread up further with this though I did enjoy the segway into a 4.070 vs 2.20 valve from 4.00 and 2.165. The OP is looking at an LSX 427 and using M311 heads on it.
I believe this all depends on what you define as a race engine, Matt.

Yea, my father can beat up your father.
Give me a break!

Instead of serving out self serving rhetoric anymore,
please define the engine performance parameters you
use to define such an engine.

And by the way; any engine builder worth his salt, uses those ratios I cited.

Granted, as you roll the head over, and reduce the valve angle,
you can move past the 52%. I wrote much about that over the
past years for the forum members.

If you don't do that, and the combustion chamber is wrong,
your shit out of luck when you get to the track, with a DNQ.

Finally, GM built 25% engines for many years, and then when
they brought out the LS3, they moved well beyond that.

Please give me comment on that, instead of handing me
incidents where people could have done better by paying
attention to the proper ratios. . .

Let's move on to defining an engine via scaling it as a percent.

Then everyone will understand that you can turn a 25% engine
into a 28.5% engine, but not into a 37% or 42% engine.
***Which would you prefer. . .

You answer those questions with me, and we can move on from
you citing how people do things wrong.

People don't need to come up on this forum to learn how to
do things wrong, they can do that on their own.

As an example; Mr. Big, he is coming up here to learn how to build his next engine, correctly.

These people deserve more than. . . I know a guy who did this, or that.

An engine that powers a car down the track, and sets some record, qualifies that engine as a performer.

Now, what were the applied sciences and / or physics that provided for that power.

The above requires quantification via the applied math.
Not, I know some guy. . . .

Finally, I am offering you the above, not as a challenge to you,
but in an effort to help to bring clarity to this complex issue.

That begins with understanding and defining a 25% engine. . . .
 
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Lol.


I should have known you were already writing a long winded response when I edited the post to try and avoid some of that wind because I really didn’t need a response anyway.

Regarding the race engine though it has s 4.560 bore with a 2.45 intake valve. Id say that is what it is but its ok if you disagree.

My only point here has been that you absolutely can run a 2.165 valve head in the 11-15* angle range on as small as a 4.00”. Bore.

If you consider a number like 52.5% to be ideal then yes a 4.125 bore would be ideal.

Both will work

Neither won’t work.

There is nothing else I need to say about the subject.

Cheers!
 

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Discussion Starter · #71 ·
So after talking to AMS, I am going to keep things bigwilly smoke and go with the attached. After thinking to myself I want to drive this car n a regular basis and be fine driving for a while I chose this block. Thoughts
 

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Lol.


I should have known you were already writing a long winded response when I edited the post to try and avoid some of that wind because I really didn’t need a response anyway.

Regarding the race engine though it has s 4.560 bore with a 2.45 intake valve. Id say that is what it is but its ok if you disagree.

My only point here has been that you absolutely can run a 2.165 valve head in the 11-15* angle range on as small as a 4.00”. Bore.

If you consider a number like 52.5% to be ideal then yes a 4.125 bore would be ideal.

Both will work

Neither won’t work.

There is nothing else I need to say about the subject.

Cheers!
I don't have any real issue regarding your comments above.

In your opinion it will work.
In mine, no, it might not work.

So why gamble!

-----------------------------------------------------------------------------

Also, why deal with a 4.0 bore, when using a 2.165" valve,
when we are assembling a performance engine?

With a real race bred, performance driven engine, we desire to 'Maximize' the HP per CID.
Not just get the best we can.
And maybe that is where you and I defer. . .

Not going to make the power a properly scaled, larger bore engine will. . .

Racers had been attempting to put larger valves in those early LS Engines for years.

The LS3 Engine came along with it's bigger bore, larger valve,
larger cylinder head runner volume, and buried the old LS Engines.

Just as the earlier LS Engines, buried the SB1 Engines.
Then along came the NASCAR SB2, which buried all before it.

What we saw was; when the bores got bigger, and we held proper
ratios with the valve, we went faster.

When we attempted to cheat the ratios, we spent money for nothing.

That is a small thumbnail overview, describing my experiences,
dating back to the early 1960's.

In the early 1960's, it was simple.
We stated: put some compression in it, put a camshaft in it, and put a valve spring in it.

Then you took off your hubcaps, and removed the air cleaner, and raced the car.
If your car (most any street car) ran faster than a 14.0, you had a fast car..lol

The so called TRW Pop Up Piston was invented in my back yard, out off a
need for more compression for SB Chevrolet engines. This piston, was to
my knowledge, the first aftermarket high perf forged piston.

I grew up and began drag racing, just around the corner from Vic Hubbard Speed & Marine.
They were on Meekland Avenue, in the Cherryland District of Hayward.

Al Hubbard, the machinist for Vic Hubbard, contacted TRW and asked them to build, and also paid for the first pistons.

TRW didn't think there was a market for them, but Al changed their minds.

Down the street (Meekland Avenue) was Ashland Grinding (Ashland District), run by Chuck.
Chuck did most all of the high perf grinding, balancing, and stroking of the crankshafts for the racers in the SF Bay Area.

And I purchased one of the first three Super Flow 300 flow benches, back in the MID 1970's.

That's how much I have been in this sport, and how much I have seen this sport change. . . .
 
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So now that the 1001 debate.lol_ between Matt and I seems to have ended, I offer the following.

As is usual, John Wallace gives credit, to where the credit should be given.

When you read the text, please notice that the percentages which can be used, come from one of the most respected cylinder head porter, developers in the USA.
That is Darin Morgan.

This text was originally written some years back on Speed Talk by Darin.
That is where John copied it from.

If anyone on this forum would like to learn about cylinder heads,
please look for Darin's most informative YouTube Videos.

Darin's explanation of why we do not want to attempt to work around these ratios, is much more involved than was mine, as he was speaking to the forum members on Speed Talk.

For those that might be interested. . . .

Here is his explanation:
Anytime you increase valve size over the above stated Valve/Bore ratio you will see
a small gain in CFM but the discharge coefficient drops and takesyour power with it.

An over shrouded valve instills a host of nasty scenario's, the two worst beingdecreased discharge coefficient and increased reversion below and above intake tuned power band.

----------------------------------------------------------------

And here is how Darin explains calculating the Discharge Coefficient:

The " Discharge Coefficient " is the measure of how efficient a given area is in regards to volume flow verses area, divided by a theoretical maximum. I use the 146 cfm/SQin and not the 137 cfm/SQin that the SAE dictated years ago just because that's what all my data has been accumulated with from day one.
***Window Area is also called (as I do) 'The Curtain Area'.

Window Area = Valve diameter * Pi * lift

window area * 146 = theoretical maximum flow for that area
***Our heads will not get anywhere near flowing 146 CFM/ Sq" of flow area.
***The highest value I use is 135 CFM / Sq", and our cylinder heads won't get close to that.


Take your flow and divide it by your theoretical maximum.
This is the ratio of effective flow area to actual flow area

This is your discharge coefficient.


-----------------------------------------------------------------

And if your CD is better, the head will perform better, and
you can also use a smaller duration camshaft.

Now, as to advertising. . .
You all can believe anything you want to, it's your money..lol

But the text below, represents the world I live in. . .

Here is a random cut and paste I made, again from SpeedTalk.
Has anyone seen the new Brodix 12 degree head! Are they out of their mind!!!!!!! They put a 2.525 valve in a 4.600 bore and then have the balls to claim that it flows 570cfm. The only place it would flow 570 is in Disney Land. Why oh god would you want to put a 2.525 valve in a 4.600 bore. The D/C is Horrible. The efficiency is absolutely the worst I have ever calculated.

By the way, they don't flow 570.

If the applied sciences and / or the applied physics don't support
the claim, I simply will not use the product.

Cheers
 

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So after talking to AMS, I am going to keep things bigwilly smoke and go with the attached. After thinking to myself I want to drive this car n a regular basis and be fine driving for a while I chose this block. Thoughts

If you chose to do that at the very least have them do the ARP 2000 bolt upgrade but Id see if you could step up a notch on crank and rods from Eagle.
 

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Discussion Starter · #75 ·
If you chose to do that at the very least have them do the ARP 2000 bolt upgrade but Id see if you could step up a notch on crank and rods from Eagle.
This engine choosing is a headache ahhh man. I think I changed my mind again. My head is spinning at the moment. I think I’m going long block from texas speed.
 

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Discussion Starter · #76 ·
Never mind they are on back order.
 

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There are other sources
There are many many options and yes it can be unnerving, no doubt.
I can't tell you what to buy or what you need/want. I WILL suggest that you RELAX, mull it over a bit, it isn't the sort of thing that one should rush into.
 

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What Mr. Surly said is spot on.

If you aren’t racing, don’t buy a racing engine.

Know your budget, know your goals, and know yourself.


Sent from my iPhone using Tapatalk
To a certain extent. These engines make power even with minor mods so you shouldnt under buy either. With that said he does not need $1800 rods and a $2500 crank.
 

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Discussion Starter · #80 ·
Finally made up my mind. Talk to them for about 30 minutes. I know they got tired of me asking questions
 

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