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Not to sidetrack illwillem but do you monitor trans temp and what is an acceptable temp to see before becoming a problem?
I have done 3 track days in 85-90 degree temps, usually run 3 sessions of about 15-20 min which equals around 9-10 laps,
coolant temp gets to 205 degree(obd fusion) and stays there and oil temp gets to 5-6 bars on gauge... The trans temp is more concerning to me as
I see temps in the 230 range...
Not to sidetrack illwillem but do you monitor trans temp and what is an acceptable temp to see before becoming a problem?
...
Trans temps surprisingly are nowhere near a problem for me on track. I have warnings set for 215 and shut down set for 230 based on the service manuals thresholds for the ATF dash light. Even tracking in 105 deg heat I've not come near the warnings. I am pulling temps right out of the exit of the trans cooler which feeds the valve body, I know the OEM temp sensor is submerged in the overflow fluid that sits in the pan so there could plausibly be a temp differential i'm just not seeing based on location but even so I wouldn't expect the delta to be that big between the two.
The one thing I am seeing in the data is a drop in oil pressure in the brake zones at the end of long straights. Its consistent so im not worried about imminent failure, but it drops as low as 25psi at 4800rpm. Lateral loads don't cause any drops, something to keep an eye on.
I also picked up a pressure sensor for the coolant system, I have the overhead in the logger and the sensor is relatively cheap so im going to start to log that data. This way ill be able to tell if there is a HG issue or if there is a bad radiator cap this should also help with testing the new radiator. As for now im going to be testing the new rad caps at the track tomorrow. it will be a huge facepalm if one of the new ones immediately solve the heat issue.
Honestly, no not really. That single bumper vent isn't going to flow more air than a seal duct system, not enough to get me from where I am now to a car that runs 20* cooler under load. The majority of the flow for that vent is also just flowing air directly onto the radiator vertical and cross supports. As far a t-stat i remember swapping it out to an OEM lexus part but I can't find any pictures of me actually doing it. Strange. Im going to order another one and throw it in just to be sure. I can take a look but does anyone know what the OEM ISF one opens at? and is there a replacement one that is know to fit and opens only slightly lower? im not a big fan of this- but im curious if there is any out there people have been using.
@illwillem Although I respect your engineering approach to make the duct ...
... My opinion is to run a few sessions without it at all (no box) and compare your realworld data... Also open up the blocked off areas of the upper grill.
The fluid inside may be waiting longer to cool down with the top half blocked off and the duct pulling in air that might just not be recirculating enough inside the air void. Also did you keep the OEM duct work for the front brakes?? I know your shields are gone from what I recall reading..
The CCS-R ran the 25hrs of Thunderhill with nothing fancy at all, but it was cold AF !!
My thoughts go back to the CCSR as well. It has done endurance races. Is that cooling system substantially different from OEM? I have never looked at their cooling system.
Maybe it’s apples to oranges since your running in such a hot climate?
My thoughts go back to the CCSR as well. It has done endurance races. Is that cooling system substantially different from OEM? I have never looked at their cooling system.
Maybe it’s apples to oranges since your running in such a hot climate?
The CCS-R's run OEM Rad & Cooling fans with open grills.
To my understanding the a/c condenser is gone and any supplemental oil cooler was added behind a cut away larger fog light section. Nothing large at all in front of the radiator.
Also the overflow coolant bottle was moved to where the battery box location.. The small light weight battery was moved behind driver seat. All CCS-R were developed using a LHD platform.
Aside from the USA one swapped out with an RC F motor, the rest are OEM setup on engine & trans.
Essentially to prove their bullet proof worthiness on the Streets & Tracks
Through these endurance tests, this was how the RC F received additional oil coolers in front of the wheels. Freeing up any unnecessary air flow restrictions.. They must know it works..
Through these endurance tests, this was how the RC F received additional oil coolers in front of the wheels. Freeing up any unnecessary air flow restrictions.. They must know it works..
Joe Z
Yeah I believe that the oem cooler is actually pretty good. Koyo is probably comparable becasue of the volume increase. Moving stuff out from the air flow path is probably the biggest gain. Another major bonus for the CSSR at the Thunderhill 25h is its typically 35-40* degrees tops. I have been 2 times and have never been so cold. There is also the old OEM racecar trick of saying "its all stock, look at our reliability", Hell thats corvettes bread-and-butter PR, where anyone who knows anything knows its total BS. I personally know a few mechanics on race teams that have told me as much (no one from the CSS-R's team though)
So did a test day at BW yesterday. temps were 60's in the AM session and mid 70's later in the day.
Did peak past 216 all day, ill have to check data though. I didn't switch out my new radiator cap after I saw this one was working. I did notice that the blow by was much worse running Buttonwillow raceway than it was at Chuckwalla I have a hunch that this track is just much much harder on the car.
A 1:53.1 is extremely fast on a street tire regardless of car. I am pretty happy with how this ISF is turning out, its blowing some peoples minds at the track that a 4door Lexus can be this fast.
^^ I'm sure you had a Fun day.. I spent quite sometime with the Chief Engineer Yaguchi-San, on several different occasions. I have much respect for the F brand and what has come out of it.. Also I have sat in some key future F models many years back and it was nice to see some of the improvements translated into the RC F / GS F..
He has since (recently) retired but we hope the next set of engineers carry on his legacy..!!
Ideal Race Track setup...
Some key videos from many years... I'm very confident with the message they were delivering..
The IS F "Skunkworks" project started in a body of an IS300 / Altezza and then part 2 moved into the 2nd Gen IS 250 / 350 chassis.. Creating the IS F "Prototype". With uncertainty if it would ever be built.
Also before the IS F CCS-R came to birth, his team early on built the not widely known
Picked up some of the Figs, solid bearing lower control arm bushings.
While the RR racing stuff was light years ahead of the OEM flobby-doo bushings the G's that the car is pulling now under braking is is causing the hardened rubber to compress and walk. How much so is evident by the witness marks on the brass shaft.
If you extrapolate the angles of deflection the foot and a half or so to the contact patch it makes sense that the car feels a bit squirmy under braking. If there were no such thing as the solid bushing I probably wouldn't even have tried to 'fix' this myself. The RR racing stuff is just fine, but since there was a solution available- and 'off the shelf' improvements are rare i figure these are a no brainer.
Out of curiosity i aligned the car after install. Yes there was a slight change in Toe. If you ever do USRS its probably not a bad idea to throw the car on a rack to get straightened out again.
Another thing I got was the Element fire extinguisher. If you haven't read about these check em out. pretty awesome stuff..
Clean install down at the drivers side seat rail.
And lastly here's the data on the oil pressure drop under braking. Its pretty dramatic...
It drops under braking to 18PSI at around 4300RPM (red trace is RPM and blue trace is oil pressure) You should see a correlational to the traces with rpm and pressure, with sudden drops in the red line are throttle lifts and should be mirrored with similar dive in the pressure to drop. What we are looking at here is the deviation on the deepest valleys in the blue are not correlating with the RPM valleys. They are ONLY appear after the straights while under the brakes. (i didnt grab a pic of the brake psi trace overlay but you can see this to be true by the plus mark on the track map showing this is happening in braking zones)
19PSI at the braking zone at the end of the straight.
Not sure what im going to do about this, if anything, it may just be one of those things this engine does. ill keep testing the oil and see if the motor is consuming itself. i should have seen it by now if it was.
My brothers LS7 has lowish oil pressure. We thought it was a problem, but then we learned that LS7s do that (especially at idle). My only point is that it surprised me and I was not comfortable with it, but it is perfectly healthy for that engine. Maybe that’s the case here.
So went to Streets of Willow Saturday, weather was nice and mild in the morning session but track was still a bit dusty from the overnight winds. After a few false starts of getting blocked on some really fast laps I had to settle for a 4th lap try to get a clean run. Its unfortunate because by then the a052 tires were already over pressure and down on peak grip. In that condition I still managed a 1:21.1. That's a legitimately fast lap when stacked up against times from ANY car, even on full slicks. Looking at the data of the first session there was a low 1:20 high 1:19 on both of the fliers where i was blocked on the last complex. In fact my best 'rolling lap' if the start finish line was moved to where i got blocked was a 1:20.4. Production car record there iirc is a 1:17 (new 720LT) for reference. New tires and a clean shot a low 1:19 high 1:18's is very conceivable.
Session 2 is always slower- Streets pavement does weird things when it gets warmed by the sun. I felt like I was driving harder and still managed a 1:21.3 and 1:21.5 back to back after some inconsiderate traffic interference. Overall pretty happy with the set up, the car slides and works its tires for sure but I like that type of balance when its manageable. The new solid figs bushings are a HUGE change in braking stability and very recommended to anyone that seriously tracks. I have one more event on these tires as they are getting a bit long in the tooth before I switch then out. I'm going to try a staggered front and rear set up next 295/30F 295/35R
Side note I got absolutely zero blow by accumulation the whole day, which confirms my suspicion that Buttonwillow is just hard on the car by nature. I was also keeping the revs lower than normal and really working on using the Tq of the motor to pull out of corners and limit wheel slip. That may also have something to do with it.
I learned a long time ago, when you are grip limited, it's easier to go fast in a higher gear. You can just mash the throttle, and let the power curve do all the work for you instead of paying attention to your throttle input to manage sliding. I clearly remember watching Bruce Sass do this on a motard at Second Creek Raceway way back in 1984. Watching him was a clinic...
Did you change anything with the radiator or ducting? Temps look really stable in this vid.
I learned a long time ago, when you are grip limited, it's easier to go fast in a higher gear. You can just mash the throttle, and let the power curve do all the work for you instead of paying attention to your throttle input to manage sliding. I clearly remember watching Bruce Sass do this on a motard at Second Creek Raceway way back in 1984. Watching him was a clinic...
Did you change anything with the radiator or ducting? Temps look really stable in this vid.
Thats exactly what i have learned over the years. Its been hard for my Honda-driving ape brain to comprehend 'loud sounds do not necessarily indicate faster speeds.' Radiator set up is the same. I did wrap some DEI heat barrier around the 1/2 inch hose that feeds the radiator overflow in its new location. It runs down the head above the headers, i figured it couldn't hurt. I believe that the temps I was seeing were brought on in large part by track the car hard in temps over 100F. As it cools down i think it should be fine, will need to address it before it starts getting hot again.
10-21-20, 01:01 PM
