6 speed clarification question

[Marcel D.]

Since we are clarifying everything let me ask something else to our fearless leaders and rule makers.

Not too long ago it was submitted a rule change request to modify the 50 lbs extra that the k20 has to carry if we use a 6 speed. Claim was denied and the answer was what I think just as ridiculous as they come that we had to submit a back to back test with the same car and driver with the 6 speed and the 5 speed.

I tought that the illustrious rule comitee would have data backing the desicion to tag 50 lbs on the 6 speed and produce such data backing their desicion.

The 6 speed was design for the type s or a2 or the SI not the a3 so if you guys can produce data backing your rule it would make me very happy.

More to come after your answer.

[joe barile]

Since we are clarifying everything let me ask something else to our fearless leaders and rule makers.

Not too long ago it was submitted a rule change request to modify the 50 lbs extra that the k20 has to carry if we use a 6 speed. Claim was denied and the answer was what I think just as ridiculous as they come that we had to submit a back to back test with the same car and driver with the 6 speed and the 5 speed.

I tought that the illustrious rule comitee would have data backing the desicion to tag 50 lbs on the 6 speed and produce such data backing their desicion.

The 6 speed was design for the type s or a2 or the SI not the a3 so if you guys can produce data backing your rule it would make me very happy.

More to come after your answer.

 

Why ask this here?

[Marcel D.]

So I can get an answer and I understand the logic behind the desicion. Plus this is the hc NASA forum. Where else if not here to get a logic explanation.

[JW Racing]

So I can get an answer and I understand the logic behind the desicion. Plus this is the hc NASA forum. Where else if not here to get a logic explanation.

Agreed.

When I was told I need to provide data with my rule request it didn't make sense. In the rule request I stated there was not sufficient data on the RC behalf. So I was told I must supply the data. Am I to spend a day running a few sessions with a 6 sp and swap in a 5 for back to back tests? If there was no data on this how can a penalty of weight be issued when it was not justified? Basing a rule on someone's "judgement" and not actual data is not right.

I will happily do back to back tests, but not on my race entry dollar and if someone provides me with a 5sp, because I don't have one.

[speedengineer]

So I have a detailed acceleration model written in Matlab code that I developed last summer. It accounts for vehicle mass, drag, rolling friction, inputted dyno data, gear ratios, shifting times, road inclination, etc. I was curious how much a 5-speed would differ from a 6-speed, so I put them through this model. Everything was the same for both cases, except the gear ratios.

 

Here is the generic vehicle data I used for both cases:

tire_dia = 24.9*0.0254;                      % Tire rolling diameter, convert inch to meter
m = (2425 + 20)*0.45359;                     % Vehicle mass, convert lbm to kg
c_d = 0.33;                                  % Drag coefficient
A_front = 2.2;                               % Frontal area [m^2]
rho = 1.149;                                 % Density at 30 C and 100 kPa
f_rolling_nominal = -150*m/(2875*0.45359);   % Rolling friction force at low speeds, estimated at -150 [N]
shifttime = 0.400;                           % Upshift time in seconds
theta_inclination = 1.65;                    % Inclination of road in degrees.  Downhill is positive. ARCTAN(deltaH/distance)

The inclination angle is the slope of the Mid-Ohio back straight. The results I post further down include times to and max speeds achieved at the end of the Mid-Ohio back straight. Exit speed at the keyhole was specified to be 65 mph for each case.

 

 

Here are the gear ratios I used for each transmission:

% RSX-s 6-speed
gr(1) = 3.266;                             
gr(2) = 2.13;                              
gr(3) = 1.517;                              
gr(4) = 1.147;                              
gr(5) = 0.921;                              
gr(6) = 0.738;                             
gr_diff = 4.389;                               

% Base RSX 5-speed
% gr(1) = 3.266;                              
% gr(2) = 1.88;                            
% gr(3) = 1.212;                             
% gr(4) = 0.921;                             
% gr(5) = 0.738;                              
% gr_diff = 4.389;

 

The Results:

Speed after 2350 feet:

5-speed = 127.16 mph

6-speed = 128.79 mph

6-speed with 50lb extra weight = 128.31 mph

Time to travel the 2350 feet:

5-speed = 15.819 seconds

6-speed = 15.455 seconds

6-speed with 50lb extra weight = 15.5061 seconds

 

Average wheel hp actually put to the ground over the 2350 feet:

(dyno maximum whp used was 202hp)

5-speed = 165.79

6-speed = 177.43

6-speed with 50lb extra weight = 177.45

 

Distance that the the 6-speed 'pulled' on the 5-speed on the straight:

20 meters, or 66 feet, which is about 5 car lengths.

 

Basically, in acceleration the 50 lbs hardly hurts you at all compared to the huge benefit the 6-speed is over the 5-speed. With the 5-speed, the ratios are simply too far apart thus your rpm falls lower after a shift, thus you average hp that you can use is lower. Granted, the 50 lbs will hurt you a bit in braking and cornering, but even considering that, I don't think the 50 lbs penalty is an unfair rule at all.

 

 

A couple plots:

Blue is 6-speed, dotted red is 5-speed.

 

[Marcel D.]

Please clarify couple of points, first, are you taking in consideration the whole track or just acceleration on a measured distance, since we need to know upshift and downshift also.

Second, the horsepower that you are taking in considerations is way above what we are actually running, You are probably at least 25-30 hp above the real numbers. Remember that the 6 speed was build for the type S or the SI and those engines rev way higher than the A3.

And I would be very interested if you plug in a model with all the existing engines to see what comes out.

I'm not debating the accuracy of your model, but is like any experiment , needs to be proved by a different method and arrive to the same result.

[speedengineer]

Yes, it is just a straight away. I chose the length of the back straight at Mid Ohio. Downshifts are free since they're done under braking, although the extra weight would at least somewhat hurt you in terms of braking and cornering g's, which isn't accounted for by this model.

 

If you provided me actual hp vs rpm data for your cars I could run it through the model.

[Marcel D.]

Working on getting you all the info.

[Karl]

these gear boxes are also stock not optimized with a final drive, that could be a huge change to the outcome.

[JW Racing]

Can you try those calculations with a 4.78 final drive in both, and the civic si 5spd gear ratios not the rsx 5spd, and 165hp at 7500 redline. It's a huge difference between the two 5spds from a standing start.

[speedengineer]

Ok, I'll run the numbers one more time, but let's make sure we've got all the correct inputs first.

 

I will use the 4.78 final drive for both

I will use the civic 5spd ratios

 

Please get me hp vs RPM in an excel file, the shape of the power curve can make a significant difference.

What vehicle weight to you want used?

Shift delay times are also slightly important, what time to you want me to use. 0.400 seconds? 0.500 seconds?

What tire diameter do you want?

[slammed_93_hatch]

When this motor was originally classed they did not have the +50lbs for the 6speed.

 

Bob Gill (the first k20a3 in h2), and the only one at the time was using his 6speed ITR box.

 

After some a few rules requests the weight came down, but they added the 6speed +50lbs.

 

I finished my car shortly after that and ran the ep3 (civicSI 5 speed). We did some data comparison (on track). Graphed HP, and gearing etc.

 

 

I stuck with the 5speed, (had a 6speed i could have installed). And Bob was very interested in switching to a 5speed.

 

 

The 5speed is flat out faster than the 6speed.

 

 

In all your calculation don't forget all the "up-shifts" where you are not accelerating any longer. depending on the track this can really add up.

[speedengineer]

Upshifts are accounted for in my model. Yesterday I ran the model again with the updated final drive ratios, lower vehicle weight, slightly smaller tire diameter, and the ep3 ratios, and the times were very, very similar (still don't have actual dyno data from somebody yet though...).

 

Results will vary depending on the track. It all comes down to the speed at which you come off of each corner. If one transmission places you right at the beginning of the peak power area of your power curve, you get the best acceleration early-on in the straight, which has a huge benefit. If you exit a corner with the car bogging, or at high rpm and have to shift immediately, you will be at a disadvantage, regardless of the number of gears of the transmission. The differences between the two transmissions will be most apparent over long periods of acceleration where multiple shifts are made, especially in standing starts. It will also be more apparent at lower speed tracks since the gear ratios are identical in the top two gears of each transmission anyway.

 

The beauty of the model is that it isn't affected by driver consistency, or varying track conditions. In my experience, lap times can vary by up to a second from the cool morning to the hot afternoon. Changing a transmission over lunch and then searching for a 1/2 second difference when the conditions have changed and most decent drivers are only consistent to half a second anyway is mighty challenging!

 

...still waiting for some actual hp vs rpm data, and answers for what I should set the other inputs to.

[AustinG]

In relations to the data that JimmyC is commenting on, while driving on Thunderhill Raceway, Bob told me that it accounted for something like an additional 12-15 shifts for the 6 speed over the 5 speed. I was led to believe that similar data was found for Sears Point. While being able to get into the "sweet spot" for certain corners, the advantage was lost due to the requirement of the additional shifting throughout the course.

[JW Racing]

Thank you Austin and Jimmy C.

 

and the times were very, very similar

 

I rest my case, the 50lb penalty is not needed. I am however just going to save up for a 5 speed and just work around the rule since it will not be over turned. This way I can do a back to back session with a traqmate from NASA swapping the two transmissions and prove to the RC this is the fact.

[joe barile]

Thank you Austin and Jimmy C.

 

and the times were very, very similar

 

I rest my case, the 50lb penalty is not needed. I am however just going to save up for a 5 speed and just work around the rule since it will not be over turned. This way I can do a back to back session with a traqmate from NASA swapping the two transmissions and prove to the RC this is the fact.

 

 

One guy says that if you machine your 6th gear to make it inoperable, you will then have a 5 speed...

[speedengineer]

Using some hp numbers that JW Racing provided me, 2420 lbs for the 6 speed, 2370 lbs for the 5 speed, and a 24.5" tall tire, 400ms shifting time, with a starting speed of 65 mph. The 5 speed was actually faster in this case, because at a starting speed of 65mph, it ended up at a more favorable rpm for the first few seconds of the straight, which is critical. At a different starting speed, the 6 speed would have been faster, it will all depend on the specific track and the corner exit speed for each track.

 

Speed after 2350 feet:

5-speed = 124.91 mph

6-speed with 50lb extra weight = 124.62 mph

 

Time to travel the 2350 feet:

5-speed = 15.73 seconds

6-speed with 50lb extra weight = 15.82 seconds

 

Average wheel hp actually put to the ground over the 2350 feet:

5-speed = 159.40

6-speed with 50lb extra weight = 161.18

 

Distance that the the 6-speed 'pulled' on the 5-speed on the straight:

negative 4 meters, or about 1 car length

[speedengineer]

So I ran the numbers again, this time from 10mph to 1500 feet, to simulate a standing start. I was fully expecting the 6-speed to dominate here, but no! I am very surprised! Between the extra shift and the 50lbs added weight, the 6-speed just barely lost to the 5-speed!

 

Took the 5-speed 14.124 seconds, the 6-speed 14.167 seconds. Only a difference of two meters between the two cars at the end of 1500 feet.

 

Now, if you take the 50 lbs off the 6speed, then it only takes it 14.087 seconds, and then beats the 5speed by 2 meters instead.

[ILIKETODRIVE]

So I ran the numbers again, this time from 10mph to 1500 feet, to simulate a standing start. I was fully expecting the 6-speed to dominate here, but no! I am very surprised! Between the extra shift and the 50lbs added weight, the 6-speed just barely lost to the 5-speed!

 

Took the 5-speed 14.124 seconds, the 6-speed 14.167 seconds. Only a difference of two meters between the two cars at the end of 1500 feet.

 

Now, if you take the 50 lbs off the 6speed, then it only takes it 14.087 seconds, and then beats the 5speed by 2 meters instead.

Split the difference? 25lb weight penalty instead?

[JW Racing]

Thank you for the work Jason. I appreciate your effort in doing the calculations using my weight, tire size and hp.

 

Well there is your data RC, it appears there is not really a need for the 50lbs penalty for a 6spd. Since there is no actual data held by the board to prove otherwise, I think this is enough evidence to support my rule request. Majority wins - 6 people with data, vs 3 with none.. Jeremy, Sam, Spencer, please reconsider my request now that there is a model providing the data you want. Thank you kindly.

 

Justin

[Marcel D.]

sorry I'm still trying to figure out how to upload data, but JW has the same and good to know that he was able to get it to you.

Here is the video of the start at the speedway, I can't think of a longer straigh where we start , and we have all the engines represented.

White Integra B20, White and red civic B18C5, Yellow Submarine K24, Crx B16, and me k20 with 6 speed.

 

Prior to this event I dyno at 160 on a dynojet at bisimoto. The rest I don't know what hp they have.

[JW Racing]

Marcel you know I side with you right, but the committee has this video to see and I don't think we have a remote case with this simulation to get any rule changes for HP or for transmission for K series H2, bottom line. I had 2 more hp at bisimoto than this crx, didn't race that day but I wish I did. So what's faster his 5 speed vs my 6 would be hard to tell unless one car and driver tests it back to back. I don't think some simulation is going to sway any decision, we need rock hard evidence from a video and a data logger with the same car/driver/hp/chassis using both transmissions.

 

[AZELISE]

White Integra B20, White and red civic B18C5, Yellow Submarine K24, Crx B16, and me k20 with 6 speed.

 

Prior to this event I dyno at 160 on a dynojet at bisimoto. The rest I don't know what hp they have.

 

White integra with a B20:

ITR transmission with a 4.7 FD and 225/50r15 RA-1's. Fuel cutout at 7200 RPM.

I weighed in at 2360 at the end of the race (similar to the minimum weight for a K20 with a 6 speed).

Engine tuned to 152 whp on a dyna pack that measures within 1% of our local dynojets.

[Marcel D.]

Thanks Doug for the input , I must correct my post , bisi is a dynapack and the hp was 158 . My final drive is 5.08 with 235/40/17 which is 24.4 diameter I think.

Let's see if the others post on the numbers

[joe barile]

Marcel you know I side with you right, but the committee has this video to see and I don't think we have a remote case with this simulation to get any rule changes for HP or for transmission for K series H2, bottom line. I had 2 more hp at bisimoto than this crx, didn't race that day but I wish I did. So what's faster his 5 speed vs my 6 would be hard to tell unless one car and driver tests it back to back. I don't think some simulation is going to sway any decision, we need rock hard evidence from a video and a data logger with the same car/driver/hp/chassis using both transmissions.

 

 

...That still may get you nowhere. The "data" is irrefutable regarding the h4 civic/crx brake sizes, and still no attempt at parity. Keep trying though....