Ooooo. Nice. A warm drivetrain for our race car will add about 3hp. Most people do the dyno day, their car sits in the lot, its their turn, strap it down, 1..2..3 pulls and done. The car isn't even warmed up yet. About a 3 hp difference from ambient drive train temps to nice and hot. For our pulls we do them all about 130F at the differential. Why 130F? I dunno. It's hotter than ambient and makes more power. About 150-160F is the most we've ever seen on the dyno and thats during tuning with long, long, long, long runs.

So.....yes you can run a better fluid and make a few more with a hot drivetrain.

FYI: The NASCAR boys actually have a qualifying oil. Not hard to find. Joe Gibbs makes a ton of this stuff for that market. Great comment.

 

Sorry dude. Fail. Look at the slope of the curve after 8,000 rpm. Dead giveaway for what they did to the motor.

 

Since the tone on here by some of you is getting nasty, here is the answer.

The dyno sheet is from a stock Star Mazda series car. Series II Renesis. Dry sump. Header. Motec. Manual throttle body. Stock injectors. Stock, stock, stock, stock stock.

Q: NOW, WHY DID IT MAKE MORE POWER????

A: The drivetrain makes less drag.

Moral of the story? A dyno doesn't record what your just your engine makes, it also has to go through your drivetrain. For the stock engine we have measured any where from 20 to 17% power loss when running motors testing on an engine dyno pulling 268-270hp. It just so happens that this transaxle driven open wheel car has less drivetrain restriction. The dry sump really does nothing on these motors other than controlling and insuring oil supply and/or that the oil pickup in the oil pan can actually capture or pickup oil. There is not the kind of benefit like a pistion car get. The manual throttle body is to run a high quality TPS sensor and not the flybywire Mazda model. The throttle body is the same size as ours. Motec engine managment allows for a zillion tuning options so it's really not the tune that gets this extra hp. I'm certain engine management products supported on this forum could get pretty dern close to what the more expensive and robust motec systems do. There are just tons of expandability, inputs, programs and features that make these things very valuable to race teams.

 

Eric,

Would it be accurate to say that most of the drivetrain loss we have is fluid based rather than weight based? I know they both have a component, I am thinking that the water pump pushing coolant around, transmission fluid churning, and diff fluid churning is probably a greater loss source than the weight of the metal bits.

Mainly thinking that from your over-8k comment. Metal doesn't produce more drag the higher you go, but I could see fluid doing so.

 

I see it as our engine spinning the driveshaft/differential much faster through a 75w90 gear oil, compared to a lower revving turbo 4, v6, v8, everything else.

I bet Honda S2000's face equal hurdles when tapping out a stock engine build.

The power seems to taper off at the perfect spot though.

 

I will be honest I didn't get the direction of the thread but I do now! Love it actually

Building our car I have the luxury of weighing 4 carbon fiber drive shafts and came up with about 13.1lbs up to 13.5lbs. I obviously used the lightest. I was wondering however if you have tried or used the steel driveshaft? I am 90% sure it is actually much lighter than the carbon fiber BUT it most likely twists more which could be a larger negative than weight. I am thinking WAY outside the box here but I did think about this during our build... Any thoughts or better first hand knowledge? (I am still a newbie with these cars...)

Stephen

 

Steel wont be lighter but Aluminum could be.

 

You should have held out longer. I was really enjoying reading all the silly comments from the forum experts ....

 

Socrates method would also question whether that dyno was from a renesis engine. That was never mentioned--only assumed!
lol.
OD

 

It was only an assumption if you are blind ...

 

http://www.mazdatrix.com/getprice.asp?partnum=3191-708A

one pound lighter, wonder how much that translates into power? Not much at all I suspect.

 

Pretty sure it's friction based. Once again the RX-8 is not a unique animal. There is tons of info on the internet about drivetrain friction---more than I'll ever know X a zillion billion gillion.

It's pretty standard that professional and pretty serious amateur racing teams have some of their drivetrain parts processed. There are two prevailing procedures that are currently used in the circles I run it: REM and WPC. Google them. There are measurable gains and some series allow for this. Some do not. Typically you do your entire trans and your ring and pinion. Others go as far as ceramic and/or very low friction wheels bearings. Why? Rolling resistance but also better heat properties, quality etc. Again, it's not just about the engine is it?

 

Here that brother Mark. It felt like we were headed down a bad road. Lots of.....interesting posts.

 

I would ask the favor of Team addressing this one. Lighter isn't always better and this is going to also confuse people. I'm going to say this again----lighter isn't always better. May I suggest we keep this thread going and have people comment on this? Mark----you have a much more qualified background that I do if you want to take this over.

Hope you all liked this brief journey. As you can see---there ain't much more in these engines contrary to what some people think. I trust this might shed light on realistic power expectations if you spend way too much money to get there.

Happy Rotoring.

 

Done.

Very cool stuff...

 

In drive shafts...lighter is always better....if strenth is the same.

I have a buddy that makes custom shafts for drag cars and such. He was always impressed with the RX-8's driveshaft. He said the reason they likely went to CF was that the RPM the shaft was expected to function in was severe...if it was heavier the harmonics would have ripped it apart...even if it was balanced perfectly.

 

I don't want to get off topic, but I would love to see this type of thread for Eric's 2 rotor 13B fuel injected street port with custom Drummond slide throttle intake with p-port exhaust and Yaw injectors.** Also the what are the drive train losses with the sequential trans setup?

 

Uh, no. I know for a fact that this engine was completely unmodified. I was present for its tear-down.

 

My first guess was going to be the motor was in a NC miata (less drivetrain loss with a shorter driveshaft right?) and my dads guess was a formula Mazda pro series car.


Glad to be thinking along the right track.

 

It doesn't really matter since you never stated any number of other pertinent data points, and using even some of your own past commentary it still doesn't matter even then. I was surprised you felt the need to even respond at all for the same reasons ....

 

No one asked.

I only posted that dyno because it seemed to me that Eric's concern, to some extent, was that people were going to raise the BS flag on his plot, when he said:
I was just pointing out that seemingly high specific outputs are not atypical in GrandAm racing, where the I presume his plot came from.

 

As he eventually stated, it was a Pro Formula Mazda racecar run on the same chassis dyno as most of the other dyno stuff he has posted (the one 270 hp engine dyno being the exception).

 

but team, why is lighter not always better?

 

Here is a hint: http://www.youtube.com/watch?v=o_w3oZsoxrg

 

I would have expected the answer to have been more obvious since he's posted it numerous times

Reminder to self, do not drink and post .... ugh