2.1 to 2.0 yeilded 55hp and 80 ft#'s torque on Dave's dyno, also went from 9.6@141 to 9.3@152 both the dyno and track #'s are on the AMS GT35r at same boost levals. David does not hold back a thing tuning my car, both were perfect safe max HP tunes.

Actually I guess you didnt read my post.

I stated in another post in this thread the fact that there were hardly any 2.1s in existence so its hard to really get any conclusive data in general. I guess I have ill-concieved notions about the motor's reliability since the only 2 people who had them running were blown up, even though 1 wasnt built by a shop and the other was used by a harsh drag racer, CB. Why are you saying you want to see physical and mathematical proof in my response...I stated " I really have not seen any conclusive data from anyone running them whatso ever" Im the one saying there really is no data so why are you asking me for it?

Going by DB's posts, I think he shares the same OPINION as me.

Thank you for the input Curt, appreciate it.

I am only speaking from what I have seen so bear with me.

I am sure if I do the math as some of you have that I will find the piston speed is lower with a 2.1 liter engine. That makes it harder to explain the broken rods and spun bearings that have seemed to happen more often than not.

Often times when firmly established principles appear to be contradicted by empirical evidence, we are quick to dismiss the principles as inaccurate hence unimportant. We accept that which is closer to physical, over what is more metaphysical and abstract. We do this because we would rather not view our understanding as erroneous or incomplete.

What we should do really, is look harder to include more factors we might have left out, or look for the inaccuracies in our old logic and experiments. When finally we understand both why certain things are happening, as well as why others are not, then that specific dynamic is considered completely understood and we can finally move on to other things. We reach this understanding by study and discussion. We may not always reach an answer, but even progress is halted, we should consider it only temporary and be ready to resume when additional logic or evidence comes to light. We should not dismiss everything before that point.

Better to say...

"I have not come to a conclusion on this issue because I haven't figured it out" or "I conclude that [thesis], but welcome any logic or evidence that is whole enough to be an alternative explanation"

..rather than.......

"Paper/concept/theory aren't accurate/worthy, so I don't care about them"

=========

For what it's worth.. the higher up in professional racing you go (rough guide being cost), the more you find it tends toward conceptual. The lower you go, the more empirical things are. Regardless of whether a level is closer to pure empiricism or at the other end, pure scientific theory, you find that the ones who retain base empirical requirement for racing, while constantly expanding their understanding of the dynamics (theory) and applying it, are the ones who progress to higher levels.

All of us currently use a mix of theory and empirical evidence - proportion of each varying. All of us face problems and we need to work together to figure things out and not dismiss theory when convenient, and yet at the same time, use it in other situations for credibility.

I say "us" and "we" because it includes others as well as me. This message is more general than it is meant for you.

you are very correct, but thats a part of engine dynamics the average-joe does not really have control over. there are so many factors like piston ring tension, ect. anything that can add to overall load and forces being put on the internals of the engine. but, basically speaking, lower mean piston speeds on paper does equal better reliability, ect. but truthfully there are too many variables. tthe thing about these failures everyone seems so worried about is that they were probably run up to a higher RPM than the 2.0's. depending on by how much, you may be at an overall equal or even higher load placed on the rods, crank, ect. heck, even runing an aluminum pulley vs a crank harmonic dampner could increse wear or lead to engine failure. too many if's for me to drag this thread out.

what i do want to say is everyone here that is against the 2.1, you are focusing on basically 2 failures. who knows how many people have a 2.1? not you, nor do I. and there have been PLENTY of 2.0 failures that cant be traced back to anything as well. purely, based on factual data, a 2.1 can rev higher reliably, and i am a fan of that. i personally wouldnt buy an engine built by a retailer in the first place. when i build an engine, i double and triple check everything, every clearance, torque, ect. and i cant be guaranteed that by buying a pre-built engine. i want to build a 2.1 eventually, once i get an evo and have the cash to build a block up. i do have some evidence, not on evo engines, but actually the toyota 3SGTE. the fastest Alltrac in the country uses a 2.1 long rod variation, makes over 900 hp to all four wheels, and is driven every day. both 2.0's and 2.1's have been proven and i would run either one, i would never run a 2.3/2.4 stroker. ill post a few exerpts from articles about long rod engines, hold on...

This is out of HOT ROD magazine, but the concepts still apply.


Again, not from the import world, but Smokey Yunick, who was a very succesful engine developer for racing was quoted to say:
granted, thats for a racing engine, but it does shed light on the fact that it is more reliable to run a long rod setup for higher RPM and RPM's that are sustained within the upper region of the rev limit (like a road course car)


Heres a good link to read:
http://e30m3performance.com/tech_articles/engine-tech/rod-ratio/kin2.htm

this expands on the idea its not all about the extra reving capability, and that you dont get a whole lot of extra reving capability out of just piston speed alone. what makes the 2.1 so good is the fact the rods are at less of an angle, and the piston "dwells" longer closer to TDC to let more air get in and out of the cylinder.

heres the rod ratio's i calculated out for a 2.4,2.3, 2.0, and 2.1"

2.0: has a rod ratio of 1.695
2.1 has a rod ratio of around 1.84
2.3 has a rod ratio of around 1.55
2.4 has a rod ratio of around1.6

for the 2.3 and 2.4 i gave them the best ratio's i could find that people can get with them, as it seems they can be built slightly differently.

for a performance engine, you want to be at least at a 1.7 or above according to most engine builders. food for thought...

The only way to settle this is at the track. Oh, I guess it's settled then;)

I second that!

Lmfao

if i had financial backing to build a car like you do Dave, i would be all about settling it at the track with a 2.1 built by yours truly. as of now, im still searching for that right evo to build ;) . but, as you said, the 2.0 is still much better to work with than a 2.3 or 2.4, and allot of people have proven that, including you, Shep, ect...

Average Joe still has control over bore and stroke.
Trade engine speed for stroke and at a given power, all loads are reduced except for one and only marginally so. It is repeated at a lower rate.
Trade engine speed for bore and at a given power, all loads are reduced. There are other dynamic tradeoffs, but none relating to loads alone. One of the remaining can be disregarded totally on a high massflow turbocharged engine.

Actually I was referring more to inertial and combustion loads.

This is true.

Given free gearing, it is power that gets you down or round a track, so maybe you should focus on power and power width?

I have responded to all the points you have listed, in previous discussions. The magazine is oversimplifying things and perpetuating outdated information.

This reduction is mostly rod tension and compression, and some for the crank at non dead center crank angles. Mag never mentions tradeoff but overall net reduction of sideload, or ring package design challenges as compression height is reduced.

Examine the technical regulations and you'll realize why (approved blocks, block heights). Talk to the guys developing the engines and they'll tell you they would like to run shorter decks, shorter rods.

Mag doesn't mention forces that rise as square of engine speed. They are not normalizing for power to isolate real effect. Comparison invalid.

Doesn't mention the miniscule degree change for fairly large drop in rod ratio.

Here the magazine is plain wrong. It cuts peak piston speeds, but not average (mean) piston speed. The only factors in mean piston speed are stroke and engine speed.

Here the magazine mentions the poor-port-crutching I mentioned earlier.
In bold, you see them contradicting themselves.
The last bit about the camshaft is a red herring becuase you can do anything you want with it whether on a high or low engine speed or rod ratio engine.

This was decades ago when heads were horrible and they needed to crutch the ports. These days outside of 4V and pneumatics, the limit is valvetrain.


Power is the target, not RPM. RPM is a by product when rules limit displacement and power is still required. I can list you some very successful road race engines that had/have rod ratios like 1.5 and ~1.4. Not just road race but endurance road race.

What happens at the track is not a pure comparison of 2.0 to 2.X engines . It is a comparison of a multitude of factors (business, rules, money, management, etc.) , so there has been nothing proven about 2.0 to 2.X .

If we compare 4G63 drag accomplishments, yes you win hands down. Those achievements are something you definitely can be proud of, but don't forget there are others who won't even step down to play in an arena they deem low brow and low tech. (Not me, or I wouldn't be on this forum). It is these same people who rely heavily on paper.

ShaunSG, you seem to know quite a bit, ill tell you that. while i agree that the first article does oversimplify things, that is only because it is a magazine read by the public, of which most do not understand much of engine dynamics. heck, ive read books and articles galore, and i still dont know anything comapred to allot of people.

i think for you, i oversimplified my responses. the fact an engine with a higher rod ratio can rev higher is great, the reason i like it is it extends the usable powerband by technically being more durable and able to rev higher and faster. same or more power over a wider powerband is definately a plus, especially for the motorsports activities i participate in.

as for the Dwell issue you dismiss, i have read a few sources that have mentioned the same thing. i dont fully understand the dynamics of that situation, but they say it happens. please elaborate. i just sketched a rough diagram out and it seems the speed would definately be slower at the top of the bore, and that it would dwell longer there due to the changed anle of the rod. could this be what they are reffering to? Here is the graph from the link i provided that maps out piston acceleration, doesnt this prove that the piston does in fact move slower at and near TDC, which proves their point?
http://e30m3performance.com/tech_art...io/accel-1.gif

Also, please list the specs on the engine(s) which have a 1.4 rod ratio. i am sure there are exceptions to the rule of thumb on acceptable rod ratio's, and maybe they can be explained by their size, bore, stroke, ect.

even though you also dismiss the effects of long rod engines as bandaids for poor ports and bad head design, i still believe that benefits would arise from a long rod setup.

I might be out in left field here, but I'm not sure the statement about having more time to get air in and out of the cylinder on the long rod motors can be accurate. The amount of time air can move in and out of the cylinder should still be limited by intake and exhaust valve open time which is a function of cam specs and RPM. Just thinking out loud.