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11K views 82 replies 15 participants last post by  Jon Lesko 
#1 ·
Starting this year off on a different note.
LSX 434 Built by Precision Racing Technologies 11.1
SPS Haymaker Heads
Frankenstein Billet Intake
ID1700's
Nick Williams Boosted 102
Twin Precision 6870's
Precision 64mm Blow Off-Valve
Precision 46mm WasteGates
Going to do a Fore Fuel system with Tripple 285 pumps
Sticking with the Mcloed Clutch for now. Hopefully we will start on the turbo kit soon.
 

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#7 ·
There are a lot of factors concerning Comp ratio, right?

The video link that was floating around with Brian Tooley discussing chamber softening for ex. He states they ran a motor a full season racing on (this is from memory):

High 12.XX:1
2X psi boost
e85
28 degrees spark advance up top

Just a data point...I just like learning :)
 
#11 · (Edited)
I agree!

Higher boost generates (should generate) a higher mass flow.
A higher mass flow means more fuel can be used.
The above in turn generates a higher 'Mass Charge'.

The 'Burn Time' of the 'Denser / Heavier' mass charge is
increased as the compression ratio is lowered.

This means one can't open the exhaust valve as quickly
as the cylinder heads exhaust port might require to
evacuate the cylinder of the exhaust gasses during
what we call the 'Blow Down' cycle.

Higher 'Static' compression helps burn the mass charge
more quickly then does a low compression engine.

This is called 'Thermal Efficiency'!

And finally;
Better exhaust ports don't require excessively large
exhaust duration lobes / camshafts..:D

Cheers
 
#10 ·
Some good info below from some..:D

A couple of other thoughts for consideration:
Longer duration camshafts many times require higher compression ratios.

The above is connected to your so called 'Dynamic Compression Ratio',
which in turn is connected to the camshafts intake valve closing event or (IVC).

The quality of the fuel definitely must be considered here,
if the 'Dynamic Compression Ratio' or 'Trapped Compression',
which is linked to the 'Mass Flow Rate' is going to increase
as engine rpm increases.

I am assuming it will with twin 6870's..lol

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

What kind of 'Sticks' out with Tank's proposed build to me though,
is the use of twin 6870's with only a 102mm TB?

Being as Tank has a custom manifold, I would suggest that he consider
rethinking the required TB inlet's area (supply side), so that it might
meet the demand of the twin 68's a bit more sufficiently.

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

Also Tank;
What size intake valves do you have in those heads?
What are the runner volumes?
What is your proposed shift rpm?

Let's not blow this one up Russell..<Big Wink>..lol

Cheers
 
#12 ·
Duck what tb would you recommend going with? I"m open to change.

So the heads are inconel exhaust valves, chambers were softened, intake valves are 2.125 67cc 11 Degree Valve Angle. 264cc/106cc
I will prob shift around 67-7000 little tough with a manual to nail that down. Cam specs are 239/253 .612/.614 118+5
 

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#15 · (Edited)
How much HP are you desiring to make Russell?

That's what will determine how much air the engine will require. . . .
And how large an TB will be determined by how much velocity your TB will handle. . .

Those heads are going to begin to go turbulent around 322 cfm.

So let's say they are going to support an engine flow of about. . .
=> (4 * 322)= 1288 cfm before they go into compressible flow.

Compressible flow is 'NO' problem for a good turbo.

1288 cfm is good for about. . .
=> 863 fwHP.

So now you have one more Turbo left..LOL
How much more do you want now. . .:p

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

The 102 mm TB has a diameter of 4.01".
and 12.68 Sq."

If you divide the 1288 cfm by the 12.68"
your arrive at 101.57 cfm / Sq."

The velocity will be 2.4 times that value.
So the velocity will be 243.79 fps.

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

Flow testing of a 'Particular' 102mm TB showed it choked at ~1660 cfm.

Choked value is assumed to be ~350 fps.
350 fps is equal to about 146 cfm / Sq.".

A 102mm TB has 12.68 Sq." of flow area.

So. . .
=> ((1660 * 2.4) / 12.68)= 315 fps.

So the 102mm TB choked 'Not' at 350 fps, but at 315 fps.

That means it flowed. . . .
=> (315 / 2.4)= 131 cfm / Sq."

The 'Discharge Constant' would be. . .
=> (131 / 146)= 89.7%

For a short explanation of the discharge constant see my signature. . . .

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

I would move that 131 cfm / Sq." down to ~110 cfm / Sq."
for a 'Max Perf' / street / strip car.

That would generate a velocity of ~264 fps.

So if you wanted 1500 fwHP then you would be desiring
for the TB to flow ~ (1500 * 1.5)= 2250 cfm.

If you divide that by 110 cfm / Sq.", you arrive at
20.45 Sq." of required flow area.

That would mean a TB of about 130mm. . . .

More HP would mean more TB area required. . LOL

Cheers
 
#17 · (Edited)
That would be to support a 1500 fwHP engine Russell
for a max perf street / strip car.

I would go even larger if it were just for the track. . .
never seeing something less than maybe 5000 rpm's.

Also. . .
I read through your post again that contains the camshaft info.
Was that a camshaft you purchased for the PD Blower?

Cheers
 
#19 ·
Throttle body size means very little when you have 30+ psi of pressure drop across it. I’ve seen 2200hp with a 90mm without breaking a sweat.
 
#21 · (Edited)
On what Mike. . .

Only on the Internet. . . . .
Not on Gasoline on a good Engine Dyno..LOL

I don't just sit here and make this stuff up!

0.55 Mach is great.
0.628 Mach is about the best I have seen.

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

One must defeat these simple principles:

The High-Perf industry states that 146 cfm / Sq." is the most
one can flow through a well radius having an area of 1 Sq."
at a depression of 28" of water.

Regarding Compressible Flow Bernoulli states:
This occurs for air flow when the absolute pressure ratio is 0.528, i.e. when the
downstream absolute pressure (P2) is 52.8% of the upstream absolute pressure (P1).
Sonic Velocity occurs for air flow when P2 /P1 equals 0.528.

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

Anyone know how to defeat the above. . . .
I know where you can get a well paying job. . LOL

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

Let me break it down then you can respond:
You got at the best 14.7 psi pressure on the inlet side of the 90mm TB.

Explain to me how your going to move 2200 fwHP
or (2200 * 1.5)= 3,300 cfm or air through an
90mm orifice that has an area of 9.8757 Sq."?

That would be. . .
=> 3300 / 9.8757)= 334.1532 cfm / Sq."

That would be. . .
=> A velocity of. . .
(334.1532 * 2.4)= 801.9676 fps velocity on a flow bench @ 28"

That would be. . .
=> (2 * 801.9676)= 1,603.9352 fps velocity in the air.

That would be. . .
=> (1603.9352 / 1116)= 1.4411 Mach

So maybe your using 'Rocket Fuel'..:eek:

===================================

Below is a post I made sometime back on this forum
regarding Bernoulli and compressible flow for reference:

-what is compressible flow-
This occurs for air flow when the absolute pressure ratio is 0.528, i.e. when the
downstream absolute pressure (P2) is 52.8% of the upstream absolute pressure (P1).
Sonic Velocity occurs for air flow when P2 /P1 equals 0.528.

Sonic velocity refers to the speed of sound and a mach number is associated with that.
In an IC Engine sonic velocity is considered to be ~55% of the speed of sound.

Most in the industry tend to agree that the value of 1116 feet per second represents
the speed of sound when referencing that phenomena with an IC Engine.

Some simply use the value of 52.8%, which correlates with the value of 0.528 given above.

As an example;
When P2 is 14.7 psia and P1 is 27.84 psia,
sonic velocity / velocity choke occurs through the orifice.

As P1 further increases there is no further increase in the velocity of the air flowing
through the orifice, but an increase in mass flow can be generated by a Supercharger as
it will compress the air molecules together thereby increasing the density of the air.

The density ratio increases at the square root of the pressure.

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

So if we add 1-BAR of boost, we have a pressure ratio of 2-BAR Absolute.

If we square root the value of 2, we arrive at a value of 1.414.
So we effectively have now added 41.4% air mass to the engine.

But to double the density we would need to have 4-BAR of Absolute Pressure,
as the square root of 4, is equal to the value of 2.

Take care Mike!
 
#22 · (Edited)
380” yates head sbf with a 101 turbo, 427” yates head sbf with a d3r procharger, 400” edelbrock headed pontiac with twin 94’s. All running on C16 before Q was available. In 99-01 worked at a shop in Alabama (Youngs Performance) that dynoed and tuned most of the first big turbo and procharger motors. We were the go to for all the heavy hitters in outlaw 10.5 and NMRA racer at the time. A 90mm was as big as was available and I don’t remember ever thinking we were hurting anything because of the throttle body. We used 4” charge tubes on everything too.

I’m not making this up I’ve seen it in reality over and over on the dyno.

I don't have tons of digital pictures from back then, but here's a picture of one motor. This was Don Walsh Jr's first procharger motor from back when he raced NMRA Pro 5.0. It was a 4XX" max effort sbf from Bennet Racing with a d3R procharger. If my memory is right it was one of the first to break 2000hp. It has a 90mm accufab. I was the machinist that built all the blower bracketry, motor plates, crank drives etc. We dyno-ed and tuned motors for Steve Petty before pro-line existed.


That's me at the lathe.
 

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#23 ·
380” yates head sbf with a 101 turbo, 427” yates head sbf with a d3r procharger, 400” edelbrock headed pontiac with twin 94’s. All running on C16 before Q was available. In 99-01 worked at a shop in Alabama (Youngs Performance) that dynoed and tuned most of the first big turbo and procharger motors. We were the go to for all the heavy hitters in outlaw 10.5 and NMRA racer at the time. A 90mm was as big as was available and I don’t remember ever thinking we were hurting anything because of the throttle body. We used 4” charge tubes on everything too.

I’m not making this up I’ve seen it in reality over and over on the dyno.

I don't have tons of digital pictures from back then, but here's a picture of one motor. This was Don Walsh Jr's first procharger motor from back when he raced NMRA Pro 5.0. It was a 4XX" max effort sbf from Bennet Racing with a d3R procharger. If my memory is right it was one of the first to break 2000hp. It has a 90mm accufab. I was the machinist that built all the blower bracketry, motor plates, crank drives etc. We dyno-ed and tuned motors for Steve Petty before pro-line existed.
Nice story and thanks for the insight and info.
I really do appreciate it..:D

I know of no way to get an orifice to flow at 1.44 Mach
in the automotive sector be it intake or exhaust.

The flow in the automotive industry is characterized as 'Subsonic Flow'.

I know of no sector within the automotive field that
deals with flows at or exceeding Mach 1.0.

On the exhaust side they use 'Nozzle Theory' which helps to accelerate
'Hot' gases to much higher speeds then I spoke about in my earlier
post to you, as I was only speaking about the intake side at that time.

They are using those sciences now in the automotive sport on the
exhaust side, to help exhaust ports flow around 200 cfm / Sq."

That flow number would then be associated with a velocity of 960 fps.
That would be equal to Mach 0.86.

But that is happening on the exhaust side, with the help of
heat and pressure to help 'propel' the exhaust gasses of some
highly sophisticated engines to approach the speed of sound.

These 'Race Teams' have budgets in the millions of dollars
each year to spend on R&D.

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

The above response is only meant to generate a reference
point between the two of us.

From reading your posts over the years, as well as participating
in some of your threads, I recognize that your not a person
that would post something up as you did without reason.

But I can't explain how an IC Engine could inhale air, at or near
the velocity of Mach 1.0, never mind exceed it by ~44%?

Steve / Karch gave a 'Like' to your post.

Steve / Karch works with the measurements of airflow,
within a much broader sector then I have.

Maybe he has some info to share?

Thanks again for your post, as posts like this,
from people like you make me think..lol

Cheers,
Bruce
 
#38 ·
I have a customer running a 2” meter downstream of a pressure reducing regulator, and he is trying to increase the flow to double what it is currently.

He’s running up against choke flow, so I suggested he move the meter to upstream the reducer, thereby increasing the gas density greatly, from 40 psig to 250 psig.

This is the stuff I do everyday, and, strangely, it’s fun for me.


Sent from my iPhone using Tapatalk
 
#48 ·
Damn. They should change the plates from ST KNG to DTH TRAP.

Sent from my SM-G965U using Tapatalk
 
#51 ·
Those 434 Engines were not LS Engines Daniel
they used variants of the GM 18* Cylinder Heads.

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

But to answer your question regarding the LS 7 heads. . .

Yes, as the LS 7 heads have a much better port layout
then does the LS 3 heads.

But you do require an adapter plate on the intake side
if your going to use them on the LSA.

While the adapter plate does not present any flow issues,
usually it is just easier for most to go with the big bore
Mast Heads on these LS Engines.

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

The LS-3 head was originally designed for the 427 CID Engine.
But it did not satisfy the flow requirements of the engineers.

So they went back to the drawing board, redesigned the head,
and that is what we are calling the LS-7 head today.

Cheers
 
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#54 ·
First off, I am so thankful that so many brilliant minds with such diverse levels of experience are so active on this forum. I've never learned so much, and I do appreciate everybody putting in their anecdotes that ultimately help us all make more well informed decisions when modifying our cars. Second, Russell, this build looks totally badass, and I will be following closely; also, that billet shift linkage you sent me for my car has been nothing short of spectacular. Every shift, solid. Now, I do not wish to hijack this thread, but while it seems all our brilliant minds are in one place, I have a question, which is probably painfully obvious to most all involved, but I am far from experienced in this realm. Right now, I am running my car NA, but when I had the engine built, the builder constructed it for a twin turbo application. Of course, the rebuild process on my car was lengthy, and I have since changed my mind, in that I am now looking towards following the Red Baron, and throwing on a ProCharger; either F-1A94 or F-1X, I haven't decided yet. My question is, would the cam I have (which was custom ground for a twin turbo setup) need to be replaced; or since it seems the centrifugal supercharger operates in a similar fashion to the turbo setup, will I be okay as is? Feel free to PM me advice, so as to keep this thread clean. Thanks!
 
#63 ·
Grab some Hydramat
 
#71 ·
Right up there with rear control arm bushings Rando, fat chance.

Had a pm about how these would be incorporated. Send me a pic of the bottom of a fore fuel pump?
 
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