Some gearing graphs

[Petrus]

Source; armstrongfamilyblog

Just increase the rev range.

C52 (C50M1 in the ZZW30)




C56




C60

[Roj]

Good info.

Someone kindly posted an XL sheet with various comparisons on a 2ZZ Conversion FB group just yesterday. It's quite useful. I'll try and figure out how to upload a file here.

[Dev]

Good work Petrus but  graphs could have been done better.

 Where it shows speed at 4k and 6k looks to be about the same. It should have parallel lines, one showing 4k and one showing 6k at their respective speed differences. It looks as though they read the same for the given RPMs.  There should be a dot on the slope at the very least. 

 Edit: after studying the graph it appears that I understand it better now. The point on the slope shows where the speed and rpms intersect between each gear as the engine speed drops off between shifts but it doesn't take into account drag and friction which slows you down during the shift.




 

[Petrus]

It´s one of the two ways I was tought them Dev. It is called the saw tooth graph.
Would have been more insightfull it the tips would be open ended at 9K with the vertical shift lines at the red line of the 1ZZ.

The second graph, which is a VERY usefull companion is a representaion of the power and torque curves calculated as function of the gera reduction. That way you can immediately see where you are in the useful power/torque band.
It is these which tell you if/when it makes sense to overrev or shortshift (in racing circumstance you nearly always want to rev as much as possible; after shifting you will hit the highest point the power graph and lose the least torque from shifting* as late as possible).

Not seen these of the 1ZZ. Imo road tests should include these as one of the basics. I remember that is sóme gear head mag(s) it was.
I am sure there must be a tool on the web nowadays.
HINT HINT 

If ´you´ have done any serious mods to the engine it makes sense to have a run n the dyno and plot these second graphs. It does not matter what the actual power/torque values are; it is about the curves.


The graph looks like this:



The high gear vs ´losses´ plotted in will show whether you could do with a lower/higher gear for top speed.
You can also factor in as much shift time loss in as you want.

*
unlike the power which stays the same, the torque at the wheels DRÓPS with shifting up:

[Mark A]

Thanks Petrus. So when Boris allows me to go to the pub again I can print this off and show all my mates that my 300bhp MR2 can achieve the 200mph barrier? Perfect 

[Petrus]

Thanks Petrus. So when Boris allows me to go to the pub again I can print this off and show all my mates that my 300bhp MR2 can achieve the 200mph barrier? Perfect 

If it has the gearing, you can plot the losses in and if it shows the power graph supersedes the losses at 200 mph than yes.
I suggest some aero mods though to get the Cw down otherwise 300 bhp will have a tough job ;-)  The Spyder has a disadvantageous shape for aero forces. It will probably get réal light and lose traction before it gets to that sort of speeds.

[Alex Knight]

Drag squares with speed.

If you had the gearing to achieve 200MPH, you'd need a LOT more than 300BHP to overcome the drag.

[Roj]

Someone* on a 2ZZ FB group posted a spreadsheet that can be used to compare different ratios of Toyota 'boxes. I asked if he minded me posting it here, he's not replied after a day, plus it was posted on a public forum for others to use, so I hope he doesn't mind

Toyota Gearbox Spreadsheet

Should be able to save your own copy and edit accordingly. Please leave this version as-is for others to use.


*Credit to Allan Jacquet from the UK MR2 2ZZ Projects group on Facebook.