Applying the DV 128 formula on a Supercharged engine

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GARY C
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Re: Applying the DV 128 formula on a Supercharged engine

Post by GARY C »

F-BIRD'88 wrote: Wed Jun 17, 2020 7:53 pm
GARY C wrote: Wed Jun 17, 2020 7:45 pm FBird wouldn't using DV's 128 for a supercharger be outside of what it's intended for?

It could be done but it would only be guess work at best without test data to back the theory.
Remember and note that it is using the DV 128 method BUT BUT with a tweek . That TWEEK is not rocket science and is the tweek that makes the BIG difference in the right area on these types of engines VS the very similar N/A version .

The goal is the same as the goal of the DV 128 method intended goal.. To get a better working cam selection than catalog or phone line or ya pick the 114 lsa cam it will be fine.
This gets you a better cam for this purpose.

Nobody has put forth ANY PROOF that the DV 128 method does NOT work as intended most of the time on these typical street strip engines.
If you can knock it.. prove it.
If the DV method does basicly WORK pretty well most of the time. This will work well too . More usable torque right where you can use it.
BUT BUT you have no TWEEK DATA! Your right It's not rocket science, DV had dyno proven data that he used to formulate 128 for the SBC.

You can't have it both ways.
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Re: Applying the DV 128 formula on a Supercharged engine

Post by F-BIRD'88 »

GARY C wrote: Wed Jun 17, 2020 8:12 pm
F-BIRD'88 wrote: Wed Jun 17, 2020 7:53 pm
GARY C wrote: Wed Jun 17, 2020 7:45 pm FBird wouldn't using DV's 128 for a supercharger be outside of what it's intended for?

It could be done but it would only be guess work at best without test data to back the theory.
Remember and note that it is using the DV 128 method BUT BUT with a tweek . That TWEEK is not rocket science and is the tweek that makes the BIG difference in the right area on these types of engines VS the very similar N/A version .

The goal is the same as the goal of the DV 128 method intended goal.. To get a better working cam selection than catalog or phone line or ya pick the 114 lsa cam it will be fine.
This gets you a better cam for this purpose.

Nobody has put forth ANY PROOF that the DV 128 method does NOT work as intended most of the time on these typical street strip engines.
If you can knock it.. prove it.
If the DV method does basicly WORK pretty well most of the time. This will work well too . More usable torque right where you can use it.
BUT BUT you have no TWEEK DATA! Your right It's not rocket science, DV had dyno proven data that he used to formulate 128 for the SBC.

You can't have it both ways.

No i don't need to TWEEK data.. Tweek the formula to match the supercharged engine Where it will matter the MOST..

Adding new relevant good data WILL HELP then allow you to fine tune it..
But as a general rule of thumb if the DV 128 method works pretty good but n these types of simple engines This TWEEK will most likely ALSO work well. on these simple typical engines that are now simply supercharged.
(not turbocharged)
Last edited by F-BIRD'88 on Wed Jun 17, 2020 8:21 pm, edited 2 times in total.
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Re: Applying the DV 128 formula on a Supercharged engine

Post by GARY C »

F-BIRD'88 wrote: Wed Jun 17, 2020 8:15 pm
GARY C wrote: Wed Jun 17, 2020 8:12 pm
F-BIRD'88 wrote: Wed Jun 17, 2020 7:53 pm

Remember and note that it is using the DV 128 method BUT BUT with a tweek . That TWEEK is not rocket science and is the tweek that makes the BIG difference in the right area on these types of engines VS the very similar N/A version .

The goal is the same as the goal of the DV 128 method intended goal.. To get a better working cam selection than catalog or phone line or ya pick the 114 lsa cam it will be fine.
This gets you a better cam for this purpose.

Nobody has put forth ANY PROOF that the DV 128 method does NOT work as intended most of the time on these typical street strip engines.
If you can knock it.. prove it.
If the DV method does basicly WORK pretty well most of the time. This will work well too . More usable torque right where you can use it.
BUT BUT you have no TWEEK DATA! Your right It's not rocket science, DV had dyno proven data that he used to formulate 128 for the SBC.

You can't have it both ways.

No i don't need to TWEEK data.. Tweek the formula to match the supercharged engine Where it will matter the MOST..
Where will it matter most and how do you know considering you made up the formula before you tested it's results?
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THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
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Re: Applying the DV 128 formula on a Supercharged engine

Post by F-BIRD'88 »

GARY C wrote: Wed Jun 17, 2020 8:19 pm
F-BIRD'88 wrote: Wed Jun 17, 2020 8:15 pm
GARY C wrote: Wed Jun 17, 2020 8:12 pm
BUT BUT you have no TWEEK DATA! Your right It's not rocket science, DV had dyno proven data that he used to formulate 128 for the SBC.

You can't have it both ways.

No i don't need to TWEEK data.. Tweek the formula to match the supercharged engine Where it will matter the MOST..
Where will it matter most and how do you know considering you made up the formula before you tested it's results?

I have not made up the new version formula for supercharged YET . This the purpose of this thread to examine what is different and what Change will MATTER THE MOST.
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Re: Applying the DV 128 formula on a Supercharged engine

Post by F-BIRD'88 »

I say there are basicly 3 big differences between the N/A engine and the supercharged engine in this class .

1. The induction side is now pressurized thus the mass air flow is increased.

2. The combustion pressure and temperature is higher now by effect of forcing more air and fuel IN under pressure.. Thus the engine compression ratio has to be lowered to keep combustion stable.. (Detonation must be avoided)

3. There is MORE exhaust mass to get rid of.
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Re: Applying the DV 128 formula on a Supercharged engine

Post by GARY C »

F-BIRD'88 wrote: Wed Jun 17, 2020 8:46 pm I say there are basicly 3 big differences between the N/A engine and the supercharged engine in this class .

1. The induction side is now pressurized thus the mass air flow is increased.

2. The combustion pressure and temperature is higher now by effect of forcing more air and fuel IN under pressure.. Thus the engine compression ratio has to be lowered to keep combustion stable.. (Detonation must be avoided)

3. There is MORE exhaust mass to get rid of.
Actually 4, if you consider hood clearance. :)
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Re: Applying the DV 128 formula on a Supercharged engine

Post by F-BIRD'88 »

If you do not like the DV 128 method thats ok.

But you must prove it to convince me its wrong.
If you don't like the DV 128 method for what It is intended for,, You may not like this method either... Ghats ok.

But your car, your street supercharged engine and your budget does not care what you like. ....
It just wants a better cam choice.
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Re: Applying the DV 128 formula on a Supercharged engine

Post by GARY C »

F-BIRD'88 wrote: Wed Jun 17, 2020 8:57 pm If you do not like the DV 128 method thats ok.

But you must prove it to convince me its wrong.
If you don't like the DV 128 method for what It is intended for,, You may not like this method either... Ghats ok.

But your car, your street supercharged engine and your budget does not care what you like. ....
It just wants a better cam choice.
Thats funny right there, I don't care who you are.

What are your latest cpl of builds using 128 and what were your results?
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THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
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Re: Applying the DV 128 formula on a Supercharged engine

Post by F-BIRD'88 »

I do believe that Controled Induction's equation method is and will be BETTER.. I can see enough of what is going on there to see the smarts in it. VERY SMART, I say...

I believe that this will get you close .. Better than ya pick the 114 lsa dual pattern cam.
Last edited by F-BIRD'88 on Wed Jun 17, 2020 9:15 pm, edited 1 time in total.
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Re: Applying the DV 128 formula on a Supercharged engine

Post by F-BIRD'88 »

My overall builds and others have Generally suprisingly shown that there is Validity in a general Trend sense of the DV 128 method.. I sure cannot dis- prove it. Can You?

It fits what I have done and seen on these types engines pretty good. . Surprisingly good.
Good is better than bad .
Prove me wrong on any of this so far.
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Re: Applying the DV 128 formula on a Supercharged engine

Post by F-BIRD'88 »

"Thats funny right there, I don't care who you are"

If you do this for a living then I AM THE GUY you will try to knock down and insult to no end . I AM THE GUY that you will NOT let me observe your dyno sessions.

I got no problem with this)

If I was you I would not let me observe EITHER
.
I am the guy that you watch run at the drag strip. And cuss under your breath at. ..
I am not your $$$ Competition, yet I am the guy you watch

I am the guy that you won't let your friend or yoUR CUSTOMER ... run for $$Money$$$...

THAT'S fUnNY!!!!...
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Re: Applying the DV 128 formula on a Supercharged engine

Post by hoffman900 »

:shock:

Might be easier if you two just texted each other.
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Re: Applying the DV 128 formula on a Supercharged engine

Post by SchmidtMotorWorks »

F-BIRD'88 wrote: Wed Jun 17, 2020 7:53 pm
Nobody has put forth ANY PROOF that the DV 128 method does NOT work as intended most of the time on these typical street strip engines.
If you can knock it.. prove it.
DV said 128 is the most important thing in specing a cam (no qualifiers for what type of engine), was that claim true or false?

What carburetor and intake manifold is the 128 method intended for?

What header diameter and length is the 128 method intended for?

What exhaust system is the 128 method intended for?

What transmission type is the 128 method intended for?

Each of those parameters alter the cam choice.
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Re: Applying the DV 128 formula on a Supercharged engine

Post by gmrocket »

F-BIRD'88 wrote: Wed Jun 17, 2020 6:05 pm
CamKing wrote: Wed Jun 17, 2020 12:24 pm
F-BIRD'88 wrote: Tue Jun 16, 2020 3:49 pm UDHarold
Unblown engines don't start putting clean air and fuel into an engine until a little while AFTER TDC. Before TDC, the piston is moving upwards and pushing the exhaust gases out the exhaust port, there is no air/fuel intake until after TDC and the piston starting down on the intake stroke.
Well, Harold was 100% wrong, when he wrote this.
Airflow doesn't know where the piston is. It flows towards the lower pressure.
As the piston movers upward, the higher pressure in the cylinder moves toward the lower pressure in the exhaust port. As the pressure decreases in the cylinder, we reduce the valve lift on the exhaust, to increase the velocity over the valve seat, changing the pressure below the exhaust valve, and increasing the pull on the cylinder. This lowers the pressure in the cylinder, below the pressure in the intake port, so as soon as the intake valve opens, you get positive flow.

A supercharged engine works the same way.
The air flows from high pressure towards low pressure, no matter where the piston is.
Yes, of course you are right about relative pressure and air flow direction from high towards low(er).

But..... What he says about when and when in reguard to intake valve opening and exhaust valve does not disagree with that at all

Agree, the roots supercharged engine is basicly the same except the relative pressure in the intake side is higher. (boost)
Remember the exhaust valve is already closing as the intake valve opens . At low rpm a bit of cross flow is not actually a bad thing on this boosted engine.
This slight cross flow disappears as rpm rises and boost rises too. A bit of egr effect to tame liw rpm combustion speed and a bit of fuel criss flow to cool things as to engine comes on the power curve. In this engine the camshaft has a slighty wider lsa than the N/A cam, the intake events are near the same. The exhaust is either same or near same duration . The cam is advanced The real difference in this cam vs the n/A cam is the exhaust events. The exhaust events work with the new relative pressures to aid exhaust extraction and get the intake stuff moving IN on the overlap
2 things you got to remember: This engine has a low compression ratio and the cylinder heads are not great.
Better than stock , but not max in any terms.
The goal is torque in the usable rpm range with fair amount of boost, Not a nice idle, not a smooth ride , not a smooth power band. Its street racer not a street rod cruiser, nor a 12-14:1 cr 30 psi alcohol funny/promod motor.

Because the intake low lift flow is relative low you want to get the intake valve open at TDC so air can really move in ss the piston now decends
. Getting the intake valve open at tdc requires starting that job before tdc (intake opening)
Whut?

You’ve got it about as backwards as you could get it.
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Re: Applying the DV 128 formula on a Supercharged engine

Post by F-BIRD'88 »

SchmidtMotorWorks wrote: Wed Jun 17, 2020 10:47 pm
F-BIRD'88 wrote: Wed Jun 17, 2020 7:53 pm
Nobody has put forth ANY PROOF that the DV 128 method does NOT work as intended most of the time on these typical street strip engines.
If you can knock it.. prove it.
DV said 128 is the most important thing in specing a cam (no qualifiers for what type of engine), was that claim true or false?

What carburetor and intake manifold is the 128 method intended for?

What header diameter and length is the 128 method intended for?

What exhaust system is the 128 method intended for?

What transmission type is the 128 method intended for?

Each of those parameters alter the cam choice.

But only in a minor way.... and DV does qualify the engine type and purpose. Very clearly.

Your problem is you want to deny that and find a way to make it much more complicated than it is.

Your shiny shoes add no value.
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