Aftermarket Lid Options - MPI

random84 said:

The going price for aftermarket lids with bricks it seems. Even OEM LS9 lids are $2k I think (used).

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Similar to what some call 'Ported TB's', this all
makes absolutely 'No Sense' to me. . .

Where is the improvement in HP after spending all of this money????

These engines come with heads having large
volume / runners (~265 cc's) and small camshafts.

Much HP is gained by replacing the camshaft.

More HP can be gained via increasing the Minimum Circular Square Area (MCSA) just below the valve Inner seat ring, to ~87% and form a new valve bowl. Also, porting of the Short Turn / SSR is highly helpful (raising of the SSR / Short Side Radius). Then put the engine on E85.

Bingo, you have a Mid 700 rwHP to mid 800 rwHP
engine, depending on what you do with the Supercharger
and TB and mass flow recovery system.

random84 said:

Air temps. It's all about keeping air temps under ~140* F for the duration of a 1/4 mile pull, as the OEM calibration starts to pull timing. With E85 or meth it's certainly less of an issue, but then people start adding more pulley and `round we go.

So much like anything else, these $3k lids are really for people trying to squeeze every little bit out of their combo.

In my case, having the original Kong lid, it was just a more durable design than the GM product and able to withstand the higher boost pressure of the 2650 rotor pack, even if the IAT "gains" were minimal or the pressure delta slightly worse. With the GM lid and brick, I was crushing fins inward at around 17-18 psi.

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Jesse,
I certainly agree with your thoughts above..

You wrote:
The going price for aftermarket lids with bricks it seems. Even OEM LS9 lids are $2k I think (used).

But I don't see where paying $2k for a used OEM LS9 Lid is worth the money (JMHO)!

While there is certainly a lot of 'Bling' factor there, I think that
spending that money elsewhere, will deliver much more HP.

Hot Rodding has always contained two camps.
One that desires to go fast, and who follows the principle of "form follows function".

Back when we still saw Hot Rods on the street with flathead engines, we could see / hear the engine had been modified, but the paint job was never completed. This then developed into the 'Rat Rod' craze some years back.

Then there were those that painted their cars with many coats of Lacquer and chromed everything, never adding any performance item that would increase the HP.

We would then call out. . If it don't go chrome it..lol

Cheers

random84 said:

Air temps. It's all about keeping air temps under ~140* F for the duration of a 1/4 mile pull, as the OEM calibration starts to pull timing. With E85 or meth it's certainly less of an issue, but then people start adding more pulley and `round we go.

So much like anything else, these $3k lids are really for people trying to squeeze every little bit out of their combo.

In my case, having the original Kong lid, it was just a more durable design than the GM product and able to withstand the higher boost pressure of the 2650 rotor pack, even if the IAT "gains" were minimal or the pressure delta slightly worse. With the GM lid and brick, I was crushing fins inward at around 17-18 psi.

Click to expand...

Therein in lies the physics which many people fail to realize.

If everything else is constant, adding a more restrictive brick, or heat exchanger, will result in less pressure seen by the map sensor and lower IAT2 on that sensor. It’s a function of the ideal gas law, plain and simple.

So really, boost pressure and temps matter less then power output. But, if temps get excessive, timing is normally pulled which will result in a drastic step down in power.

When the 2650 came out, I specifically asked, twice I think, what the BSFC was.

Nobody even tried to answer.

Granted, probably nobody knew the answer but my intent was less about knowing the answer but my failed attempt to get people to understand that you might (likely) will make more (peak) power, but at a cost (independent of capital outlay).

The costs are in fuel, but also in power to drive the blower.

Unless the design of the blower is significantly better than the prior design (not likely), then the added mass alone (and friction) will cost more power (torque) to not only drive the bigger blower but to accelerate those larger rotors.

Let’s imagine the larger rotors weighed the same (highly unlikely)…even then it would cost more energy to accelerate those larger (and less dense) rotors because their center of mass will be further from the axis (think of a spinning figure skater (even a hot one) who moves her arms in and out.

So that’s where I was going with that unanswered question.

Since nobody here cares about using more fuel as long as you get more net power to the wheels, we can choose to not look at fuel consumption from a monetary cost perspective.

But some actually want to accelerate their cars faster, and for this, you need a higher net power over the range that the engine is operating during acceleration.

Which then leads me to this as my own rule of thumb, or perhaps assumption, since I don’t have quantifiable data…

On a 376” engine, I believe you will lose more power trying to accelerate and drive a 2650 blower than you will be able to gain when compared to a well ported 1900 blower over a 1/4 mile pass.

Now, run a 427 and an all out build and I would be hesitant to make that same argument. You have a lot more torque available, plus you have to opportunity to utilize much better flowing heads, so the 1900 becomes a major limiting factor in being able to efficiently transfer the incoming air into the cylinders.

Just food for thought.


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Karch said:

Therein in lies the physics which many people fail to realize.

If everything else is constant, adding a more restrictive brick, or heat exchanger, will result in less pressure seen by the map sensor and lower IAT2 on that sensor. It’s a function of the ideal gas law, plain and simple.

So really, boost pressure and temps matter less then power output. But, if temps get excessive, timing is normally pulled which will result in a drastic step down in power.

When the 2650 came out, I specifically asked, twice I think, what the BSFC was. Nobody even tried to answer.

Granted, probably nobody knew the answer but my intent was less about knowing the answer but my failed attempt to get people to understand that you might (likely) will make more (peak) power, but at a cost (independent of capital outlay).

The costs are in fuel, but also in power to drive the blower.

Unless the design of the blower is significantly better than the prior design (not likely), then the added mass alone (and friction) will cost more power (torque) to not only drive the bigger blower but to accelerate those larger rotors.

Let’s imagine the larger rotors weighed the same (highly unlikely)…even then it would cost more energy to accelerate those larger (and less dense) rotors because their center of mass will be further from the axis (think of a spinning figure skater (even a hot one) who moves her arms in and out.

So that’s where I was going with that unanswered question.

Since nobody here cares about using more fuel as long as you get more net power to the wheels, we can choose to not look at fuel consumption from a monetary cost perspective.

But some actually want to accelerate their cars faster, and for this, you need a higher net power over the range that the engine is operating during acceleration.

Which then leads me to this as my own rule of thumb, or perhaps assumption, since I don’t have quantifiable data…

On a 376” engine, I believe you will lose more power trying to accelerate and drive a 2650 blower than you will be able to gain when compared to a well ported 1900 blower over a 1/4 mile pass.

Now, run a 427 and an all out build and I would be hesitant to make that same argument. You have a lot more torque available, plus you have to opportunity to utilize much better flowing heads, so the 1900 becomes a major limiting factor in being able to efficiently transfer the incoming air into the cylinders.

Just food for thought.


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Click to expand...

Nicely written my friend..

You wrote:
"When the 2650 came out, I specifically asked, twice I think, what the BSFC was.
Nobody even tried to answer."

Interestingly, the BSFC is something we work with all the time on an Engine Dyno.

But I have only heard a couple of people that attempt to work with it on a Chassis Dyno.

It's a real simple calculation. . .



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

-NA engine on gasoline-
Good HP can be had if the BSFC drops to about 0.42.

Cylinder heads are a big part of this, as we would need to see about 2.4 fwHp per CFM to achieve that BSFC.

-example-
If the heads flow about 300 cfm, then we would desire to see the fwHp at 720.

Karch said:

Therein in lies the physics which many people fail to realize.

If everything else is constant, adding a more restrictive brick, or heat exchanger, will result in less pressure seen by the map sensor and lower IAT2 on that sensor. It’s a function of the ideal gas law, plain and simple.

So really, boost pressure and temps matter less then power output. But, if temps get excessive, timing is normally pulled which will result in a drastic step down in power.

When the 2650 came out, I specifically asked, twice I think, what the BSFC was.

Nobody even tried to answer.

Granted, probably nobody knew the answer but my intent was less about knowing the answer but my failed attempt to get people to understand that you might (likely) will make more (peak) power, but at a cost (independent of capital outlay).

The costs are in fuel, but also in power to drive the blower.

Unless the design of the blower is significantly better than the prior design (not likely), then the added mass alone (and friction) will cost more power (torque) to not only drive the bigger blower but to accelerate those larger rotors.

Let’s imagine the larger rotors weighed the same (highly unlikely)…even then it would cost more energy to accelerate those larger (and less dense) rotors because their center of mass will be further from the axis (think of a spinning figure skater (even a hot one) who moves her arms in and out.

So that’s where I was going with that unanswered question.

Since nobody here cares about using more fuel as long as you get more net power to the wheels, we can choose to not look at fuel consumption from a monetary cost perspective.

But some actually want to accelerate their cars faster, and for this, you need a higher net power over the range that the engine is operating during acceleration.

Which then leads me to this as my own rule of thumb, or perhaps assumption, since I don’t have quantifiable data…

On a 376” engine, I believe you will lose more power trying to accelerate and drive a 2650 blower than you will be able to gain when compared to a well ported 1900 blower over a 1/4 mile pass.

Now, run a 427 and an all out build and I would be hesitant to make that same argument. You have a lot more torque available, plus you have to opportunity to utilize much better flowing heads, so the 1900 becomes a major limiting factor in being able to efficiently transfer the incoming air into the cylinders.

Just food for thought.


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Click to expand...

Nice post, Steve.

I vaguely remember these topics being tossed around on the board. In my particular case, because I had what I thought would be a "better" TVS2300 with the LSA conversion I was happy for my daily. I would say "less rotating mass and plenty of boost with the TVS2300!" on my 400" build when the Kong 2650 first broke onto the scene... I think I was six months into getting the 2.3L ported by Jokerz at that time. Then it died while I was still seating the rings in the motor. Ergo, for me it was then an easy decision: 1.9L or 2650. and since I was essentially starting over, having already sold off the 1.9L; it was MUCH easier to just jump up to the bigger blower just because.

I have a smaller pulley in the garage I haven't gotten around to using, because 18-19psi on my "basic" pulley level with the 2650 is plenty (~850 RWHP on 93 pump) From what I remember - and I didn't get many good pulls on the ported 2.3L - it was something like this:

Heavily ported 1.9L on a medium build 376: 16psi and 650 RWHP (pump gas, 21-22* advance)
Converted 2.3L on a bigger 400" build: 16-18 psi but it died within 50 miles.
Out of the box 2650 on bigger 400" build: 19psi and 850 RWHP (pump, high compression but 21* advance)

Matt has extensive experience with the 2.3L on Corvettes, but getting them to work on the LSA is the issue. Even the other aftermarket variations never seemed to be all that successful - and then the cost jumps up similar to the 2650 offerings. IMHO for us LSA guys, it's an easy decision:

1.9L for everything 376
2650 for everything else.

Arguing about IAT2s vs efficiency vs rotor mass, etc is theoretically interesting, but realistically pointless given the variations in ambient temps/combos and cams, plus the limitations of the sensor... so unless we get a porter to weigh the rotor packs and we do a back-to-back swap, it will remain largely conjecture I think. I personally am confident that, on my combo, the 2650 was worth every penny over a 1.9L. The Kong lid is the only thing I really regret, but only because it was the more expensive option when I had to replace my intercooler and it was slightly less efficient from what I gleaned off my IAT2 and MAP readings. However, it has remained VERY durable and I didn't have to pull any timing.

rpol78 said:

When I was first looking at the 2650 I saw that it was more efficient than the 2300 or so Eaton says. I've always wondered how this played into the debate of HP to drive it, IATs, etc. They don't show anything like this for the 1900 vs 2300. Also they don't show the basis for their metrics. For example 18% less input power - is that with or without boost, does this mean it takes 18% less power to drive a 2650 than a 2300 or is it a delta from what they'd expect it to take to drive a 2650, etc.

From Eaton on the 2650:

R2650 advantages over R2300:

• 4% more efficient
• 15% larger displacement (2650cc versus 2300cc)
• 18% less input power required
• 25% more air flow at 18,000 RPM and 14 psi boost (2.0 pressure ratio)

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Please notice that everything above is referenced
to 2.0 BAR Absolute (ABS). Pressure Ratio.

This is because once you move these inefficient roots style blowers above about 19 psi, these blowers begin to produce to much heat.

So then, one would surmise that one would desire to use a blower large enough to produce maybe 19 psi of boost (nothing more) which would amount to a 2.29 ABS Pressure Ratio. This setup would also require a highly efficient mass flow recovery system.

Anything over that and your engine must rotate a
heavier assembly, and also fight inertia on the shifts.

This would be one of the reasons
the 2300 works on the 376 LS9 so well.

If anyone desires to move through the math, we can do that. . .

But we would not desire to put a 2650 roots style blower on a 2.0 Liter Engine..