Thunder Roadster Oil Cooler Line Sizing

[driftopia]

Looking for feedback on this.

I have noticed that on all Thunder Roadsters with the Yamaha motors, the oil cooler lines are 8AN. In my experience, 10AN is the minimum recommended for proper flow. Is there a reason to keep the line sizes so small on these engines?

I am working on improving the oil cooling of the motor as temps sit around 290 in sustained race conditions. I have already remounted the oil cooler in front of the radiator for a 5-10 degree improvement. A change to 10AN or even 12AN lines throughout should help with flow and add a bit of capacity. 

[Pat Conlon]

Chris, did you know our FJ forum sponsor is a guy named Randy Raduechel who happens to be the 2009 National Champion in Thunder Roadsters?

You're in good hands here....


http://www.rpmracingca.com/about.asp

Cheers

Pat

[driftopia]

Thanks, Pat. I will reach out to him. I'm finding that public documentation is scarce on these cars. I may end up being the guinea pig for a lot of the changes I am making, which I am perfectly ok with. And will share my findings with you guys.

Really, what I need is 20 more hp and better heat control to make the Yamaha motor competitive. As is, the car has one of the liquid-cooled heads, which is a pretty cool design. I just need to get the oil temp under control.

[JMR]

Getting oil temp under control in an FJ is a tall order. They run hot to begin with. Put them in an enclosed area and pin the throttle for 20 minutes and things get real interesting. I don't have much experience with the Legend engines other than working on a couple of heads. What I did notice was the threads pulled out of every cam cap bolt hole and the saddles and caps needed to be align honed. One head had oil spray bars installed in the cam cover which I guess helps but when the oil is as hot as the sun the benefit is diminished. Anyway....I hope you find a viable solution. As a side note I have -8 lines for my earl's cooler which I believe is 13 rows and as large as I could get in that space....no problems ever.

[RPM - Robert]

-10 wont help anything there isn't enough oil pressure to need that much line. We run two large coolers and one small cooler.

The large coolers are fed from the main side of the oil pump via the main oil galley. We run -8 on these lines.

The small cooler is fed from the oil pan and returns to the oil pan which is the secondary side of the oil pump. We run -6 on these. We run in central California with 110f plus days and the hottest we ever see even in those hot temps is around 240f oil temps. In the cooler months we have to tape the coolers off to get them to temp.

You need some head fans on that thing to get some air flow to the head. We also run a side duct underneath the header with a 3" naca duct the flows over the side of the cylinders.

Proper front ducting to the coolers will go a long way as well. The side of the ducting feeds the large oil coolers. The lower part of the center feeds the small oil cooler and the top of the center duct goes directly to the head/cylinders. In the second to last picture you can see the inlet of the side duct for the cylinders as well. I don't have a picture of it all done but the top gets sealed up as well. That way the only place for air to go is through a cooler or directly to the engine.

Sorry I would snap more pics but all of our cars have been converted to Hayabusa.

[driftopia]

Thanks, Robert. A little more context. I was rewatching race footage, and oil temps spiked at 290 but seemed to sit at 275-280. This was in Nashville with 90-degree temps. After this event, I moved the side mount oil cooler to the front of the radiator. My car has the liquid-cooled head jacket. Temps afterward were about the same at the Barber event. Around 95 ambient, but over 130 on track. (jack stands were melting into the asphalt because it was so hot.)

Temps stayed about the same in this configuration, but I didn't have the high spike. Coolant temp went from 140 to 150 with the oil cooler in front. At this point, I believe I should either run a second oil cooler or maybe convert to or add a laminar flow unit. I believe there should be enough room in the coolant loop to support more heat shedding this way.

As you mentioned, I need to look into the ducting now. The car has a fully shrouded radiator inlet box, but the naca ducts on the front do not go anywhere. Routing those properly should get me quite a bit of airflow over the top. And I will look into the fans on top of the engine. I have seen that configuration online a few times.

[RPM - Robert]

The side duct won't really help with that watercooled cylinder jacket. Especially if the water temp is already that cool.

That stock location in the side pod area on the passenger side was the first thing we changed on all of our cars. Adding a second and even third cooler would help quite a bit, especially if you get the ducting to force air right through them them.

Controlling the head temps will make the engine run a lot longer. They tend to blow head gaskets on the #3/4 cylinder exhaust side I've seen some get some hot the aluminum softens and the stud starts to "fall over" makes for getting the head and cylinders off a royal pain.

[driftopia]

Agreed. I may replicate a bit of your layout. Add a second oil cooler in series and use the lower NACA's to force air through them.