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Discussion Starter #1
Did anybody watch the new episode yet? They had a big stroker Dart Ford with a Vortech supercharger on it. They did a Dart 195cc as cast N/A then F/I and then switched to a Dart 225cc CNC'd head N/A then F/I. N/A made a BIG difference. F/I made 11hp more up top, and actually lost about 10hp down low.

With so much talk about heads on OUR engines, are we really ONLY gaining ~20 real world HPs woth a huge $$$ output for heads?
 

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That completely depends on how hard you’re leaning on the engine and what other mods you have.

On our blower type power adders, mass air flow through the engine while keeping boost and rpm in the sweet spot for the blow is where power comes from.

Heads will reduce boost but help move more air. Good flowing heads can also have an effect on burn rate and fuel air mixing for an even controlled burn. All of that can impact ignition timing.

There’s way more variables than just the blanket assessment that a head will deliver XXhp. We are trying to create a symbiotic environment where the cylinder heads, valve events, and blower are all in their efficiency island together while keeping the charge air as cool as possible to maximize charge density and limit the risk of preignition due to charge temps.

I’m sure Bruce will be along to quantify what I have claimed with numbers to make it a little easier to see the relationships between all the numbers.


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All FI is not created equal. You don't understand how our blowers work if you think heads don't matter.

Because these blowers can't pump effectively at higher PSI, blower has to be matched to engine flow of which heads play a part.

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Discussion Starter #4
I didn't say they don't matter. I've read hundreds of pages of builds on here. I've seen RD post TONS of info about 100% fill, MORE than 100% fill, how much more HP COULD be made with e85. That's why I wss wondering about real world differences.
 

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Discussion Starter #7
I should have put the "heads don't matter with boost" in quotes. Sorry. That was what they were testing in the episode. That wasn't my summation.I fixed the title. Sorry again.
 

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Discussion Starter #8
Let me ask you this. Is HP all that matters? How about efficiency?

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No, it's not REALLY all that matters. They DID make the 11hp with 1 less # of boost, wgich they said might help it run cooler.

I thought it would be a good discussion, just like on the show. Are PD blowers that much different than a centrifical superchargers or turbos?
 

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Yes PD blowers are quite different than the other two and IMO harder to make power with because the engine flow matters so much more. More "design" has to go into the build.

Their conclusion is a bit simplistic and probably meant to create controversy as that is what everything seems to be about these days.

It really depends what you are doing. Junkyard build, low budget, then no. Not shooting for big power, then no.

But if you want to truly build an engine well, you look at your goals, pick bore to stroke, match heads, valve size and cam, and in this case blower as well.

I have never done a cam on an engine without doing the heads too, but again, it depends what you are trying to do.

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Bruce could do a video of him analyzing their video like Gale Banks does.

 

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Let me ask you this. Is HP all that matters? How about efficiency?

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And how about torque, especially at low engine RPM?
 

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Yes PD blowers are quite different than the other two and IMO harder to make power with because the engine flow matters so much more. More "design" has to go into the build.

Their conclusion is a bit simplistic and probably meant to create controversy as that is what everything seems to be about these days.

It really depends what you are doing. Junkyard build, low budget, then no. Not shooting for big power, then no.

But if you want to truly build an engine well, you look at your goals, pick bore to stroke, match heads, valve size and cam, and in this case blower as well.

I have never done a cam on an engine without doing the heads too, but again, it depends what you are trying to do.

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Wow, great post!
I think we will just turn this thread over to you… LOL
 
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Did anybody watch the new episode yet? They had a big stroker Dart Ford with a Vortech supercharger on it. They did a Dart 195cc as cast N/A then F/I and then switched to a Dart 225cc CNC'd head N/A then F/I. N/A made a BIG difference. F/I made 11hp more up top, and actually lost about 10hp down low.

With so much talk about heads on OUR engines, are we really ONLY gaining ~20 real world HPs woth a huge $$$ output for heads?
Centrifugal blowers are not PD blowers as Arctic mentioned. Also the cam will either favor N/A setups more OR it will favor a blown setup more (and again a PD vs Centrifugal vs Turbo having differences).

But we also have factory cams that benefit a lot from extra exhaust duration and minimal overlap. A N/A cam may have more intake and more overlap because of reliance on atmospheric pressure, which would bleed off boost in a supercharged application.


Real world results on our platform, generally compared to factory heads and cam? 20HP gain across the board on ported heads. Aftermarket heads with cam, could be 40-50 HP with much of that in the middle of the power band. No one does a head swap without a cam swap - because it's a waste of money and potential!


A better comparison would involve cam changes for the blown application.

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Without seeing the episode, I'm guessing this "Big Stroker" had a middle of the road cam with longer intake duration and decent overlap, probably with higher compression, because that's "old school" and makes for better throttle response.

They then dyno and make good power.

Then they add the blower and make more power (but not nearly as much as they should). However, it's more power than the N/A setup so great, let's move on.

Except now they change heads, and ported heads probably favor gains on the intake, at the expense of exhaust, while they kept the same N/A cam that further prioritizes intake duration at the expense of exhaust duration. And that overlap? Under boost all that desirable intake velocity gets pushed right out the exhaust valve, which is probably why they lost torque and significantly limited any gains from the head swap. So yeah, they did it wrong.

That's my theory!
 

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Without seeing the episode, I'm guessing this "Big Stroker" had a middle of the road cam with longer intake duration and decent overlap, probably with higher compression, because that's "old school" and makes for better throttle response.

They then dyno and make good power.

Then they add the blower and make more power (but not nearly as much as they should). However, it's more power than the N/A setup so great, let's move on.

Except now they change heads, and ported heads probably favor gains on the intake, at the expense of exhaust, while they kept the same N/A cam that further prioritizes intake duration at the expense of exhaust duration. And that overlap? Under boost all that desirable intake velocity gets pushed right out the exhaust valve, which is probably why they lost torque and significantly limited any gains from the head swap. So yeah, they did it wrong.

That's my theory!
Big differences in the camshaft requirements for an NA Engine, Centrifugal Blower and an DD / PD Blower.

I have not watched the video.

Time vs. Money
Videos, as are the magazine articles, are always compromised in some way or another.

Blades just went from 625 HP to 710 HP with a change in heads.
Blades, correct me if I am wrong, but I believe that was the only change you made. . . Correct!

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

-as a general guideline-
For every CFM of air your engine inhales, your engine will produce ~1.0 fwHP.

-as a general guideline-
Your torque curve pretty much gives you a look at the CFM Flow Rate / Mass Flow Rate
that your engine is consuming. Piston Speed / Motion, is demanding a specific CFM at various crank angles, and the question becomes. . . Can your induction system 'Supply It'?

Peak Volumetric Efficiency (VE%) is found at Peak Torque Engine RPM.

As your Engine RPM is increased, you will understand that even
though the CFM Flow Rate / Mass Flow Rate is increased after
peak torque rpm, the Mass Flow Rates VE% is 'Decreasing'.

-in general-
PD / DD Blowers make huge torque improvements at lower engine rpm.

As the speed of the blower is increased, they become very inefficient.
Therefore, they are not the best blower to use to maximize fwHP

Expanding on what other forum members have stated above;
Our engine platform uses a small blower and a small TB.

Therefore, our engine platforms are running in a restricted form.
Therefore, low engine rpm torque will not be compromised, but fwHP will be.

Couple the two statements above, and one realizes why our dyno
charts show almost equal 'Peak Torque' and 'Peak HP' numbers.

Couple the above with Random's comment about requiring a
numerically higher LSA / LCA (Lobe Center Angle) value as we
simply can't afford to blow the mass charge out the exhaust side.

If this were not the case, we could run more positive overlap,
run a smaller exhaust valve, allowing one to run a larger intake
valve, if we moved the valve guides. We could also open the
exhaust valve a little later.

As it is, we have a low compression / low efficiency engine.

This means the 'Burn Angle' is slow. Opening the exhaust
valve early to compensate for the zero overlap requirement
means we are not burning all the fuel, as the burn angle
is so slow.

I am not going to attempt to go into depth here regarding the
various porting techniques regarding NA or any of the varying
FI methods, but later I will touch on how I approach building
an engine for a PD / DD Blower.

In my opinion, they would all require a different cylinder head!

So, reducing this all down; both the cylinder head and the
camshaft requirements would be different regarding all of
the variations seen regarding the various blowers.

In the case of the PD / DD applications; since these blowers
won't hold a high pressure ratio, then we must pay attention
regarding valve size to bore size ratios, where we need to put
the maximum sized intake valve we can into the head, which
is very similar to how we approach the building of an NA Engine.

At what engine rpm will we be shifting at?
We then extrapolate what the piston speed is.

That delivers to us the Piston CFM Demand at any
crank angle if desired, or we simply work with the
'Mean Piston CFM'.

Now we must look at the 'Supply Side'. . .

This leads us to what the bore size too valve size ratio must be?

This then tells one what size the port / runner must
be, and then that tells one what the camshaft requirements
must be. We determine what the camshaft requirements are,
after we verify the cylinder head flow on the bench.

Most likely none of that was done within this video, and it
appears from the comments within this thread that the
video has served to complicate, rather than clarify. . . .

Again, nothing new as 'Time is Money'..:(

Cheers,
RD
 
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Big differences in the camshaft requirements for an NA Engine, Centrifugal Blower and an DD / PD Blower.

I have not watched the video.

Time vs. Money
Videos, as are the magazine articles, are always compromised in some way or another.

Blades just went from 625 HP to 710 HP with a change in heads.
Blades, correct me if I am wrong, but I believe that was the only change you made. . . Correct!

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

-as a general guideline-
For every CFM of air your engine inhales, your engine will produce ~1.0 fwHP.

-as a general guideline-
Your torque curve pretty much gives you a look at the CFM Flow Rate / Mass Flow Rate
that your engine is consuming. Piston Speed / Motion, is demanding a specific CFM at various crank angles, and the question becomes. . . Can your induction system 'Supply It'?

Peak Volumetric Efficiency (VE%) is found at Peak Torque Engine RPM.

As your Engine RPM is increased, you will understand that even
though the CFM Flow Rate / Mass Flow Rate is increased after
peak torque rpm, the Mass Flow Rates VE% is 'Decreasing'.

-in general-
PD / DD Blowers make huge torque improvements at lower engine rpm.

As the speed of the blower is increased, they become very inefficient.
Therefore, they are not the best blower to use to maximize fwHP

Expanding on what other forum members have stated above;
Our engine platform uses a small blower and a small TB.

Therefore, our engine platforms are running in a restricted form.
Therefore, torque will not be compromised, but fwHP will be.

Couple the two statements above, and one realizes why our dyno
charts show almost equal 'Peak Torque' and 'Peak HP' numbers.

Couple the above with Random's comment about requiring a
numerically higher LSA / LCA (Lobe Center Angle) value as we
simply can't afford to blow the mass charge out the exhaust side.

If this were not the case, we could run more positive overlap,
run a smaller exhaust valve allowing us to run a larger intake
valve, if we moved the valve guides. We could also open the
exhaust valve a little later.

As it is, we have a low compression / low efficiency engine.

This means the 'Burn Angle' is slow. Opening the exhaust
valve early to compensate for the zero overlap requirement
means we are not burning all the fuel, as the burn angle
is so slow.

I am not going to attempt to go into depth here regarding the
various porting techniques regarding NA or any of the varying
FI methods, but later I will touch on how I approach building
an engine for a PD / DD Blower.

In my opinion, they would all require a different cylinder head!

So, reducing this all down; both the cylinder head and the
camshaft requirements would be different regarding all of
the variations seen regarding the various blowers.

In the case of the PD / DD applications; since these blowers
won't hold a high pressure ratio, then we must pay attention
regarding valve size to bore size ratios, where we need to put
the maximum sized intake valve we can into the engine, which
is very similar to how we approach the building of an NA Engine.

At what engine rpm will we be shifting at?
We then extrapolate what the piston speed is.

That delivers to us the Piston CFM Demand at any
crank angle if desired, or we simply work with the
'Mean Piston CFM'.

Now we must look at the 'Supply Side'. . .

This leads us to what the bore size too valve size relationship
must be. This then tells one what size the port / runner must
be, and then that tells one what the camshaft requirements
must be. We do this after we verify the cylinder head flow
on the bench.

Most likely none of that was done within this video, and it
appears from the comments within this thread that the
video has served to complicate, rather than clarify. . . .

Again, nothing new as 'Time is Money'..:(

Cheers,
RD
Heads and Jokerz blower. We wanted to maximize roots blower flow with the specs of Matt's Stage 2 cam.
 

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Heads and Jokerz blower. We wanted to maximize roots blower flow with the specs of Matt's Stage 2 cam.
That's right, thanks for replying Raymond!

Then if we increase the cylinder heads ability to flow more air / remove
restrictions, and the camshaft is correct, we then need to insure that the
induction systems components, which lead to the cylinder head, can
'Supply' an sufficient volume of air.

Cheers,
Bruce
 
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