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The viscous LSD in the car is junk. As soon as it gets any heat it becomes open and it doesn't do much resisting to begin with.
Torsen diff is my next upgrade, but I'll probably never do it. I was looking at the Z1 kit where they supply a whole unit and it's the better part of $4k for new gears, a new center, pumpkin, shafts, installed and setup shipped to your door. You could just change the center out but then you're off the road for quite a while as you do the conversion and get the lap set, etc.
It is easily the next biggest weakness of the car tho. As for cooling, I would go with your current plan. Buddy of mine with the z1 400hp kit races his car with just the NISMO diff cover and good oil and has never had problems with heat.
I think you're getting far enough in to race car territory already that a clunky diff isn't going to change much.
I think I've already destroyed any LSD properties on my vLSD. In the cold it starts fine, but once it gets to operating temp it barely does anything.
And from what I understand, the helical LSDs (Torsen, Wavetrac, Quaife, etc.) don't really make any more noise than a regular diff, assuming whoever installing it has it installed properly. The clutch style ones (Cusco, OS Giken) chatter a bit, but yeah #becauseracecar.
So a double post/quick update on the Z1 subframe collars (and I suppose the urethane diff bushing as well) from a quick session on the track.
Did 5 20 minute runs at Buttonwillow Raceway this weekend, and from what I can further tell from pushing the car on the track, the rear end does feel a TINY bit more settled through some of the rougher sections as well as when you hop curbs. I haven't made any other changes to my suspension nor alignment settings since the last time I was here sometime last year.
However, as previously stated (and similar to the results on the street), the main difference you will really feel will be in transitional throttle response - I could get on the power much sooner and with much quicker reaction times than I could before, even with the automatic. Obviously, the auto lags. But manually shifting it, and knowing when to apply power makes the best use of those two mods.
That being said, my brake calipers are now gold due to heat. It's pretty sweet.
I just signed up for my 1st track day this year at Road America with the Northwoods Shelby Club on Sunday, April 29th. I will try to avoid the parking lot and crowds of people so no Mustangs take me out.
Anyone else going to this event? It is long overdue for me since I did not get to do one single track day last year due to the bad Z1 tune that took almost a year to get sorted. Instead, I got to listen to all of you talk about how much fun your track days were.
New this year I will have digital temps for coolant and oil that I am very much looking forward to. My wife also got me a go pro for my birthday so I may have some video footage if I can figure it out.
I put in 4.083 gears last week and they are fun in town in the lower gears. I just hope I don't top out as Road America has some long straights.
Next week I am installing a new radiator and hoses. Then I have plans for my grille to bring in more air, a rain guard, motor mounts, subframe collars, swap oil, diff oil, brake fluid, brake pads, put on summer tires, etc, etc... Who knows how much of this I will actually get done.
Is there something wrong with your current radiator or are you installing a larger-capacity unit? That CSF triple-pass unit looks the bomb. Just hope it has better build quality than the two-row POS spec'ed for the 7AT.
Stock radiator is fine, but not for Road America. I am upgrading to Mishimoto since I have heard a few people complain about the CSF leaking. I was also leaning toward the CSF until I started digging into it a bit further.
Do any of you guys use a diff cooler or have you found other solutions for the heat this thing produces on big tracks with long straights?
The last time I was at Road America the rear diff got so hot that it melted the ABS sensors and I lost my ABS brakes. Not cool.
So now I have a Z1 larger capacity diff cover with cooling fins, run Redline 75w90 fluid, and plan to wrap my Stillen exhaust in heat wrap around the diff just for the track day. Hopefully all of this will work.
Also, now that I will be able to monitor oil and coolant temps, what temp is too hot. In other words, what temp do I see that makes me want to pull off track before something bad happens. It looks like my Nissan blue (long life) coolant I will be putting in tomorrow is good to 265 so do I want to pull off if I see 240?
I took a long drive yesterday on some country roads to add miles to the diff to break in the new rear gears. It looks like oil sits at about 158 degrees and coolant about 186 degrees. This is at 35-45 degrees air temp so that may change. I have an oil cooler so I think I should be ok.
From my time with overheating cars I've learned that getting the heat out is far more beneficial than getting cool air in. Nothing is better than a vented hood for this. It's not ideal with keeping the elements out, but will likely solve all of your front end heat problems. The negative pressure on the top of the hood, once accessed by venting, will draw more air in, vent that air out and keep it from going under the car. It does a lot more than most people think.
The better trick is where to place those vents. 1/3 up the length of the bonnet is best, as that's where the lowest pressure is, but the vent also needs to be behind the radiator, which often clashes. As you move closer to the back of the hood, the windscreen generates a high pressure region, which you want to stay away from. Then also the design of the vent matters. The best is to have a raised section in front of a hole, this creates more low pressure to suck air out of the vents. Race cars often have that sunk air slot, which is more to do with rule compliance than optimum cooling. It's better than no curved surface, but not as good as a raised lip.
See a few videos I did a long time ago with my 260z:
opening hood to demonstrate high pressure at windscreen:
Of course, a bigger radiator is not a bad idea, but is more of a bandaid than the vented hood.
As I said before, I think you're diff cooling will be sufficient, you've done pretty much everything except spend $1,000 on an external reservoir solution, which very few hardcore track junkies even have.
Nice! I suggest you copy this into the Review thread.
Do you have an external exchanger for the trans fluid? I'm sorely tempted but I doubt I'll track my G again. Never had shifting issues on the street.
Will do.
And no, the car currently does not have a trans fluid cooler nor a diff cooler - and I agree, they both are things the car sorely needs. I'm hesitant to track this car more than I already do, and that's limiting myself to one or two events a year, during the winter months to keep temps low.
Splitter, my second car was an old Datsun Roadster with a front-hinged hood. The latch wasn't all that good and it was fun to watch the hood rise as I went faster. Never had a cooling issue even when the latch worked but it was amusing none the less.
Startibartfast- thanks for the temps! I am so glad I can keep an eye on this now while on track.
Splitter- thanks for the videos. That is interesting to see the high pressure zone created by the windshield when you pop the hood.
I really hope the new Mishimoto radiator helps so I am going to do at least one track day with it before I get a hood, but I am definitely considering a vented hood.
I was thinking about a Carbon Creations carbon fiber vented hood or Duraflex fiberglass hood and either paint it or carbon wrap it. (I'm still trying to figure out if there is some way I can have a full carbon fiber hood without it looking weird on my white car- carbon wrap the roof to match?) They both look almost identical in shape and I believe I can close off the vents for daily driving.
I also really like the Autokits carbon fiber hood that has small vents behind the radiator and some larger vents off to the sides. I think it looks nicer than the other hoods, but of course it costs more and the vents are not as big so it probably would not work as well for getting heat out. It looks like the vents also seal up when not in use ie. street driving.
03-23-2018, 01:39 PM
