Got some dyno time - what should I look for?

[SiCook]

Hi.

I hope this is the right place to post these questions.....

I\'m going to book some time on a local dyno for my Rex (not long to go now...) to do a power run and generally see how healthy it is...

I\'m used to running a turbo piston engine on the same dyno and know to make sure there\'s plenty of air flow, that it\'s warmed through and that it\'s allowed to cool before the engine is switched off.

For a rotary though, particularly the FD-3S - is there anything else I should be careful about?  I\'d hate to pop the engine on a dyno within weeks of getting the car.

On the other side though I do want to spend some time with it on a dyno to check ....erm..... stuff.  What stuff should I be looking at?  It\'s a standard FD-3S Type RS.  I\'d like a baseline power run to keep for reference to possible future mods.

While the Rex is on the dyno I may as well ask them to check on other things - what other things I don\'t really know - will they be the same things as for a piston engine, or are there particular things to check for with a rotary?

Lastly, I don\'t know how experienced the garage concerned are with rotaries so given that is there anything I should really avoid or anything I should really ensure happens?

Cheers,
Si.

[maximtaylor]

Make sure you keep printouts of your runs - try to get torque curve, hp curve, boost curve and air fuel ratio curve if possible and a few of us can no doubt look over them if you put them on the forum

Being that your car is stock, you should get somewhere around 220 hp at the wheels.

Other than that, with a stock ECU you can\'t do much to cure, but it would be good for a health check.

Just do the usual beforehand to ensure that car is ready for the dyno - fluids, plugs etc.

Regards

Max

[SiCook]

Thanks - will do.  The dyno draws a single graph and it\'s power in kW vs. road speed in kph.  In the past I\'ve used a spreadsheet to work out torque and bhp and the like.  For those I need to know gearing so I\'m looking around the site to find a list of gear ratios for the car.

The dyno doesn\'t give much up in the way of other information, but they\'ll have it plugged into other test kit that may help.

I think I\'ll take it to somewhere that can plot more than the power vs. road speed because for this car at least it\'s a clean start for me.

I\'ll take a scan of everything I can get hold of before I leave and post them for comments.

From your answer though I\'m guessing that there isn\'t anything particular to rotaries that I need to do or not do when I take it to the dyno?

Another newbie question to prepare you...  Again I\'m searching through the list for the answer, but just in case...   Ignition Timing on a Rotary...   It\'s straightforward on a piston engine, is at least the measurement of it the same on the rotary?  Do both plugs per rotor fire at the same time, or are they staggered?

Thanks,
Si.

[20B_boy]

They \'re staggered - hence you see discussion of \'split timing\' i.e. how many degrees apart the leading and trailing plugs fire...

Big subject - lots of different views, some guys seem to want to fight to the death over the subject (especially some of the \'no split=best power-brigade)...

[SiCook]

Scary - I think I\'ll stand back from the ignition for a good while then and just read up on it.  I\'m assuming the A/F ratio should be the same as for a piston engine, etc (not that I know the figure, but I can tell Mr Dyno Man if it should be the same or not)....?  I\'m used to a single turbo piston engine and that runs exceptionally rich, the claim being the overfuelling is used to cool the cylinders.   One of the best ways to recover power from that engine is to modify the fuelling to reduce the excess fuel being injected.

That\'s something I\'m not going to try on the Rex (yet (c:  ) but would the theory be the same?  Do they run very rich on boost....?

I\'m not looking for lots of power at the moment, although I know my time will come.  I\'m more interested in knowing the car is in good health and getting a good baseline for future modes.  Reliabiliy is what I\'m seeking at the moment.  In the future I\'ll be chasing useable torque rather than big BHP figures.

I know the car is in very good condition now, so the idea is if I dyno it now and get some plots/info on how it\'s behaving I should be able to use those as a yardstick to keep on top of things in the future and perhaps pick up on anything before it goes pop.

Are there wiring/engine/tech documents available for these cars?  I have collected Toyota workshop manuals for almost everything that is (was) in my \'2 and I\'d like to start doing the same for the Rex -  are they readily obtained?

Sorry - so many questions.....

Cheers,
Si.

[Fish]

Si, who\'s dyno are you going to be using?

Dan

[maximtaylor]

Si

Yes you have answered most of your questions yourself

Fuelling they do tend to run rich, around 11:1 when on boost is normal and what you should be aiming for.

FYI Aftermarket ECU\'s such as the Apexi tend to run at around 10:1 on a fairly stock engine - a proper throat burning ratio! Like you say put there for safety and cooling.

There is a set of pdf documents on

//www.iluvmyrx7.com

should you want them - remember though US site so LHD but most info is correct.

Regards

Max

[SiCook]

Thanks for the info and pointers.  The Dyno is T&M in Colchester.  I\'ve been there a few times for group power runs and single bookings with my \'2 (which is being collected and taken away on Monday).

They have a refreshing attitude of priorities, first one is a healthy well balanced engine, then they\'ll start to advise on getting more power.

I\'m going to take it there at least initially to get a comparison with the \'2 so I can gain an idea of how the power delivery changes between them.

A power run for both on the same dyno should give me a more subjective idea than the seat-of-the-pants-dyno that I so often use :rollin

Also as I said I want to get a baseline on the Rex and it seems like a good opportunity to do so.  The garage are into their rallying (if only I had the money) and it\'s always fun to hear the next installment.

I\'m off to read PDF\'s ...  (c:

(left handed smilies)
Cheers,
Si.