2.0L Advantages?

[TunaTalon]

Tuna, this is good info. Have your mach calcultions take into consideration temperature? Since a boosted car commonly exhibits higher intake charge temp, the speed of sound in the intake manifold is faster. This is one reason why boosted systems do well with shorter runner intakes.

The c of an intake charge at 60*F is 1117.974 ft/sec. The c of an intake charge at 160*F is 1220.81 ft/sec. Of course, pressure has no effect on c, but that is almost a 10% increase in c.

Also, I think a wet shot would drastically lower that "wall" because c would drastically drop. But, a few around here have added a wet kit a seen a rise in power all the way to 8K. No head work .

Bigger valves seam to help greatly with 8500+ rev limits. Of course then, that's not stock 4g63.

Good point dsm-onster. Dropping the charge temperature 100 degrees F will increase the mach number by about 8%. That would raise the RPM for .51 mach from 8000 to 8640 RPM. This is also a good argument for bigger and better intercoolers.

When I started the document I knew that the speed of sound was different at different altitudes and conflated the altitude differences with the change in pressure. I wasted over two hours trying to “prove” that pressure does make a difference in the speed of sound. Oh well being old and stubborn has other advantages.

The mach number calculations in StrokeOrNot were from Wallace Racing - Mach Index Calculator (Reference 33). That calculator does not allow entering different temperatures. It makes the same assumptions for each entry and so isolates the effects only of valve size and lift. I started a more comprehensive home brew calculation in the ScratchPad worksheet of the Excel project but abandoned it because the scope of the document was already suffering from an advanced case of scope creep.

Bigger valves have a dramatic effect on the mach number because the open area increases with the square of the valve diameter. On my stroker I went with 1mm over SS valves and some bowl work to de-shroud the valves.

Oh, and the “wall” is more like a fence made of tightly woven from bungee cord.

 

[dsm-onster]

Dropping the charge temperature 100 degrees F will increase the mach number by about 8%.

Remember that mach value goes up for HIGHER intake temps. Therefore having hotter air allows one to run shorter runners to the *second* harmonic. Aftercooling makes longer runners neccesary because c goes down.

And c is not related to pressure at all. 50 psi or 5 psi or vacuum. This is because "the air pressure and the density of air are proportional at the same temperature". It's all explained fairly well in that link I posted. Do you have a list of different air velocities at different altitudes or something?

I was considering increasing valve size on my head. . . I am seriously looking at this now.

 

[90laserRSfwd]

Did you decide on a stroker or not yet ?

 

[T is for TURBO]

Definately.


Yes it is much harder on bearings than a 2.0 if you rev it to 8k. Unless you are planning on doing that pretty often however, I think the bearings will be fine. Stock 4G64 (2.4L) uses the same length stroke crankshaft and same rod length as the 2.3L, 4G64s seem to hold up well enough when they aren't rediculously abused. My 4G64 had ~143K on it when it was pulled from a totalled '03 Galant. Upon teardown and inspection, the bearings all looked pretty damn good.

I'm not saying that they won't be alright. I'm saying that they WILL be subject to more stress, regardless of rotational speed. There is no arguing it, it's physics. Also, a stock 64 motor can't be compared to a stroker motor for our cars because the strokers we put in our dsms are in there to put down lots of torque. Apples to oranges.

-Shawn

 

[delta448]

I'm not saying that they won't be alright. I'm saying that they WILL be subject to more stress, regardless of rotational speed. There is no arguing it, it's physics.

I agree 100%, longer lever arm...

Also, a stock 64 motor can't be compared to a stroker motor for our cars because the strokers we put in our dsms are in there to put down lots of torque. Apples to oranges.

How does that not apply? The 4G64 has the same critical dimensions as the stroker. The stroker crank is the 64 crank, also the 63 and 64 share the same rod length, so a stroker and a 64 have the same rod ratio. The 64 is actually capable of significantly more torque because of it's larger bore size (when similarly turbocharged obviously).

Did you mean it's different because of stress that the turbo system imparts on the stroker vs a N/A high-mileage 64? -My plan for the 64 is to eventually replace the 63 bottom end. -I can certainly agree that N/A is different, but I was trying to give an example of low bearing load, high mileage vs high bearing load, low mileage. Maybe I shouldn't have assumed that the bearing wear will be similar. I only meant to provide some assurance that the stroker will survive as long as it's handled responsibly, not to discredit you.

 

[90laserRSfwd]

It's easier on the transmission, shifting at a lower RPM, something that favors the stroker power band wise, although the added torque is harder on the trans. Just some more info for you in case you hadn't thought of that yet.

 

[T is for TURBO]

I agree 100%, longer lever arm...

How does that not apply? The 4G64 has the same critical dimensions as the stroker. The stroker crank is the 64 crank, also the 63 and 64 share the same rod length, so a stroker and a 64 have the same rod ratio. The 64 is actually capable of significantly more torque because of it's larger bore size (when similarly turbocharged obviously).

Did you mean it's different because of stress that the turbo system imparts on the stroker vs a N/A high-mileage 64? -My plan for the 64 is to eventually replace the 63 bottom end. -I can certainly agree that N/A is different, but I was trying to give an example of low bearing load, high mileage vs high bearing load, low mileage. Maybe I shouldn't have assumed that the bearing wear will be similar. I only meant to provide some assurance that the stroker will survive as long as it's handled responsibly, not to discredit you.

yes, that is what I am saying. I'm saying you can't compare N/A vs Turbo because in the DSM world, a turbo stroker is put together to make more torque. In an apples to apples and oranges to oranges situation, it all depeneds on the driver and maintance. But as the power levels increase with a stoker motor, so do the stress levels. The extra amount of wear that at 2.4 will see vs a 2.0 is neglagable in a stock for stock situation. But as the torque increase, the wear will be more aparant.

-Shawn

So I guess we agree?

 

[Defiant]

Than I think you need to let John Shepherd know that because apparently he's doing something wrong revving it passed 9k.

Just Kidding

Seriously though, please don't hurt me

When you put the money and development into your engine that John has in his, then you can rev away.

Or, you could take that amount of money and buy most of a house.

 

[slowgsr]

When i build a spare 4g63 i will be keeping stock stroke, i can more then meet my goals with it.