So about these Pony Cars for ITR...

[Knestis]

What Ron said. Travis, I appreciate the effort but you are using a 4 valve, dual overhead cam motor as your "base" and then expecting other motors to have similar specific output. They don't.

There's a disconnect somewhere here, Jeff. The specific output math is being done as a ratio, relative to a bogey value set by this Integra. This really ought not be ONE specific make/model but a mythical car that represents our basic assumptions re: IT power gains but it's a useful place to start.

"Specific output" is merely the stock power, considering displacement (and in this case, number of cylinders).

K

 

[Knestis]

...272 rear wheel hp is not obtainable in IT trim. ...Anyhow, about the best that can be expected of the 1994/1995 Mustang GT 5L is around 235-250 rear wheel hp given the IT limitations and the inherit engine design. ...

...and let's not get bound up thinking that "WHP" in this situation is supposed to be REAL wheel HP. It's a new way of thinking of our "IT Power" figure. It's mythical.

K

 

[JeffYoung]

Kirk, I may be reading it wrong, but isn't the 19.44 number in Travis' formula a "bogey" power output per cylinder that is derived from Integra numbers -- a dual OHC, high compression, 4 valve motor?

If so, you simply can't use that figure as a basis for predicting the power output of 2v low compression motors, or rotaries for that matter.

There's a disconnect somewhere here, Jeff. The specific output math is being done as a ratio, relative to a bogey value set by this Integra. This really ought not be ONE specific make/model but a mythical car that represents our basic assumptions re: IT power gains but it's a useful place to start.

"Specific output" is merely the stock power, considering displacement (and in this case, number of cylinders).

K

 

[tnord]

Ron -

I agree that the shortcoming of the model is that it's going to have to "fixate" on a specific engine type. perhaps it might work better if i used a SOHC as the baseline for output/L/cyl?

i used 225 for the Mustang because i thought i read in your proposal that it was the max offered across years of the 5.0 mustang. anyway, i initially balked at the number my model spit out as well. but reading through your proposal i found that the number produced by the model isn't far at all from what you predicted as torque output. the proposal even recognizes that a consideration needs to be made for torque even though the power output may meet the 25% standard.

looking at it from the perspective i hinted at above in that "we don't care if you have a peaky motor with high hp, or a really torquey one that runs out of breath" the output number really could be looked at as potential HP or torque, depending on engine architecture. big bore short stroke vs small bore long stroke.

i dunno, i'd like to see how that power multiplier translates into min weight and see if it is close to what you proposed or not. i'm outside of my knowledge base here with the OHV V8 stuff, and very open to input.

 

[lateapex911]

Mythical yes, but it would need to function in the real world, and if used, it needs to not shake up the existing weights, as you pointed out.

Our current system is rather simple, is transparent regarding make and model for the most part, and is conservative by default.

If it's going to work, it needs to jive with reality to the same degree or more that the current system does.

 

[tnord]

What Ron said. Travis, I appreciate the effort but you are using a 4 valve, dual overhead cam motor as your "base" and then expecting other motors to have similar specific output. They don't.

i agree, and i just used the DOHC non-VTEC Integra motor just to get an idea of a "bogey" number that we may be looking for because off the top of my head, it best hit the current 25% assumption as closely as anything i knew of.

what people more familiar with engines, and those on the ITAC should do is come up with a more reasonable "bogey number" and i can re-run everything with that in mind. anyone know of a SOHC motor that hits the 25% right on the nose?

 

[tnord]

There's a disconnect somewhere here, Jeff. The specific output math is being done as a ratio, relative to a bogey value set by this Integra. This really ought not be ONE specific make/model but a mythical car that represents our basic assumptions re: IT power gains but it's a useful place to start.

"Specific output" is merely the stock power, considering displacement (and in this case, number of cylinders).

K

exactly. i'm not saying the 19.44 is the perfect number that works everywhere, it was just a generic number i came up with to see if my model was even in the ballpark.

i think it is.

 

[Ron Earp]

Ron -

I agree that the shortcoming of the model is that it's going to have to "fixate" on a specific engine type. perhaps it might work better if i used a SOHC as the baseline for output/L/cyl?

The model doesn't have to fixate on one standard. We just have a different modifer for each engine type, easy enough. This isn't going to work well if you assume from the outset you'll be able to use one normalization factor for all engine types. I would hope that the OHV Ford example just showed that to be the case.

 

[Andy Bettencourt]

Try this one: 1.3L 160hp.

Snafu.

It may work for a few cars but it has to work for hundreds. Sell me on how this is any better than what we have now.

 

[tnord]

certainly possible Ron, i'd leave that up to others whether that gets too complex, and opens the door too wide for lobbying on just what each type should make....and the consequential constant fiddling.

 

[JeffYoung]

Travis, just a quick thanks. THought I don't fully agree with you I do appreciate the effort and this is an intriguing idea.

In any event, lots of ideas here get torn apart without much appreciation for the effort. Thanks for taking the time to do this.

 

[tnord]

Try this one: 1.3L 160hp.

Snafu.

It may work for a few cars but it has to work for hundreds. Sell me on how this is any better than what we have now.

i thought of that....but dismissed it because rotaries always have, and probably always will require special attention. same as now.

but just for funzies....

the 1.3L thing is misleading no? isn't it really more of a 2.6L? using a "4cyl 2.6L" as the model, it comes up with a 31.95% adder and 171hp.

and i really don't know if it is any better than what we have now. my first post states as such, with the qualifier that "if we're going to go down this road, this is how i would do it." i think the biggest selling point for me so far, is that it treats all "types" of motors the same, and in my mind ends the whole arguement for yet another adder/subtracter for torque. should make the VTEC guys happy as well.

 

[tnord]

Travis, just a quick thanks. THought I don't fully agree with you I do appreciate the effort and this is an intriguing idea.

In any event, lots of ideas here get torn apart without much appreciation for the effort. Thanks for taking the time to do this.

no problem, it's getting me back in the racing mindset after a couple months sabbatical.

 

[Knestis]

The model doesn't have to fixate on one standard. We just have a different modifer for each engine type, easy enough. This isn't going to work well if you assume from the outset you'll be able to use one normalization factor for all engine types. I would hope that the OHV Ford example just showed that to be the case.

...but at least at first blush, this seems to be accommodated by the math that determines the ratio. There's NO NEED to assign different values because they're inherent to the specific power figure for each make/model. Assuming of course that we accept the first principle assumption that "some engines have greater IT power potential than others, and the higher the STOCK specific output, the less potential they have." Of course, we also assume it's a linear function, in this example.

ALL that the 19.44 number needs to do is equal "1" when divided by itself, as the denominator of the ratio.

...but WHOOPS. I had a simple spreadsheet error (6-cylinder Integra!) that dorks up the numbers I posted for ITA. Replace the above with...

Integra RS et al. - 2541
Miata 1.6 - 2058
CRX Si - 2019
Sentra SER - 2596

K

 

[Knestis]

Try this one: 1.3L 160hp.

Snafu.

It may work for a few cars but it has to work for hundreds. Sell me on how this is any better than what we have now.

NOT FAIR, Andy. We don't apply the current system to the Rotaries and you know it. We reverse-derived the ITS RX7 13B multiplier to make it fit.

Bzzt. Wrong. Sorry.

K

 

[tnord]

...but WHOOPS. I had a simple spreadsheet error (6-cylinder Integra!) that dorks up the numbers I posted for ITA. Replace the above with...

Integra RS et al. - 2541
Miata 1.6 - 2058
CRX Si - 2019
Sentra SER - 2596

K

that obviously won't work. both the miata and CRX is too low. SE-R and Integra look good though. this is before any +/- for DW and FWD right?

 

[Ron Earp]

...but at least at first blush, this seems to be accommodated by the math that determines the ratio. There's NO NEED to assign different values because they're inherent to the specific power figure for each make/model.

I think you do unless I have this all farked up, which is possible - I'm on DayQuil and drugged up.

In each of the examples the specific engine output is being compared to the Integra's specific engine output and this ratio is then being used to create a % gain for the engine in question. How far away from the Integra hp/L/cyl output the engine in question is will determine the modifier. This assumes that each engine can produce the same hp/L/cyl output as the Integra.

With the 5L Ford:

215hp / 5L = 43 hp/L. 43hp/L / 8 cylinders = 5.4 hp/L/cylinder. <===very low hp/L/Cyl

5.4hp/L/cyl ((5.4 - 19.44) / 19.44) / 3 * 100 = -24.07% <====very high modifier because the difference between the Ford and Integra is (5.4 - 19.44). If the Ford output was 19.44 hp/L/cyl then this modifer would be zero because the Ford motor acheived the same output as the Integra. With a zero modifer then the assumed again would be 25 - 0 = 25%.

25 - (-24.07) = 49.07, or a 49.07% gain. <==== Produces an unobtainable gain for the Ford because of the assumption that all motors can reach the specific output of the Integra engine.

215 * 1.49 * 0.85 = 272 REAR WHEEL HP <==== Not obtainable with a 5L Ford in IT trim.

 

[lateapex911]

OK, i'm not feeling particularly bright today...but. ....I'll make a fool of myself anyway.

Ron, even though that number is high, isn't the goal to incorporate torque in the equation, thereby eliminating it from the "adder" aspect?

So, if that number then gets multiplied into weight, would it come out where the process would put it WITH the 100 pound (or so) tq adder?

I certainly see the problems with outliers, (the rotaries are just too different to accommodate, and that's fine, we can continue with them as is..). Interesting exploration.

 

[Ron Earp]

Ron, even though that number is high, isn't the goal to incorporate torque in the equation, thereby eliminating it from the "adder" aspect?

Is that the goal? I hadn't seen anything about torque on this model. I was just following along with Travis and using the proposed mode and the horsepower/L/cyl. I think something like this could work, but it'd have to incorporate the fact that not all engine designs will be able to achieve the specific output of the "bogey".

However, since there are not that many engine designs in IT I don't think it'd be a big deal to have a few different specific output targets:

DOHC 4 valve
SOHC 2 valve
OHV
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[tnord]

ron you've got the math exactly right, but as i mentioned, i'm not dead set on the 1.8L 4cyl DOHC non VTEC Honda motor as being the "poster child" of effeciency per cylinder. you could certainly be right in that i've come up with a bogey number that is too high. just keep in mind that the number has nothing to do with the Integra specifically, but should just be a value that is a good middle-ground number to apply across all of IT. pretty tough to do, maybe impossible. it's just an honest exercise to see if what a lot of people are crying for is feasible.

also keep in mind that your 272 number does not necessarily have to represent HP, think of it as "output." i'm struggling with the methodoligy to make this work logically.....but the end result seems to be in line.

since HP and torque are so closely related, one just being a calculation of the other, what if we used the greater of the two values, no matter the measure as a starting point? and lets replace our HP/L/cyl language with output/L/cyl. perhaps the model works for all the other cars listed because they coincidentally have HP figures higher than lb/ft, as is usually the case with 4 and most 6 cyl. but when we run across an entirely different type of engine that turns that upside down, maybe we should just consider the greater of the two numbers? after all, we (well actually, just me) have already made the assertion that HP and TQ are to be treated equally.

....well, turns out that didn't work at all. it does bring the "adder" value down a bit, but results in silly expected tq numbers. like 350lb/ft silly. the thought process i still think has some validity, so i'll leave it up.

i think the model seems to work if i can find a good reason to start the calculation with a HP figure, but then accept that the number it spits out could be either HP or lb/ft. that's why i went down the path of starting with the higher of the two numbers and going from there. the V8s seem to be causing me some difficulty. surprise!