So I prepping my car for nasa time trials. Right now, I'm sorting out the cooling system and getting it ready for sustained high-rpm use. Knowing that the water pump tends to cavitate at about 6500, I want to do the whole underdrive routine with the pulleys. Now, I'm not 100% sure I want to run a lightened crank pulley. That being said, will the Gspec (N1 replica) water pump pulley be enough on its own. I know the UR pulleys work in conjunction with the undersized crank pulley and oversized water pump pulley. From what I have read, the Gspec WP pulley is supposed to be even larger the the UR WP pulley, leading me to believe that it could work by itself (meaning keeping the crank pulley stock).

Any ideas? I need the engine reliable to the 7800rpm fuel cut.

Thanks in advance.

I might trust that for a one-off track event, but I would not have that as part of my plan for something to be used frequently for track events.

What are your reasons for not wanting to run the UR crank pulley? Dozens of cars have run them in wheel to wheel racing (which is harder on the car than time trials) without issue.

Koyo radiator, pulley, and get an oil cooler. Anything less on a car that is regularly tracked and you will have issues. Likely spun bearings or other problems...

FWIW have you already completed HPDE to be able to run TT?

Get your bearings/pistons/rings WPC treated. After this you might not need an oil cooler, but your engine will be more reliable.

Koyo radiator, pulley, and get an oil cooler. Anything less on a car that is regularly tracked and you will have issues. Likely spun bearings or other problems...

FWIW have you already completed HPDE to be able to run TT?

Understood. I'm already planning on the radiator and oil cooler, I wouldn't consider anything less. But I am talking specifically about the water pump cavitation issue and whether the larger WP pulley underdrives the pump enough, or is the crank pulley a necessity.

And to your question, no I have not completed HPDE yet. I know I need too before TT. I'm just planning ahead :) I will be attending numerous HPDE events starting next season. In the mean time, I am making sure my car is squared away.

I might trust that for a one-off track event, but I would not have that as part of my plan for something to be used frequently for track events.

Please explain. Are you suggesting I go another route? Right now I was planning on the usual radiator, oil cooler, pulley setup. The only other setup I had put thought to was going with an electric water pump.

What are your reasons for not wanting to run the UR crank pulley? Dozens of cars have run them in wheel to wheel racing (which is harder on the car than time trials) without issue.

Call me paranoid, but I do believe there is some truth to the whole dampening effects of the stock crank pulley. I'm not 100% opposed to running the UR crank pulley, rather I'd simply like to avoid it if I can. That is why I posted this thread in the first place. Do I need/should I run the crank pulley? I have one lined up to buy at a good price, I'm just trying to make up my mind on the matter. I'm just focused on reliability and I am worried the crank pulley might bring about some ill effects. Perhaps, i'm over paranoid. I really do want to run the UR crank pulley, for more reasons then just the underdriving effect, I just thought it would be smart to avoid it if I can.

Get your bearings/pistons/rings WPC treated. After this you might not need an oil cooler, but your engine will be more reliable.

agreed...but probably wont happen...at least not to the car's current engine.


To all, thanks for the input! By all means, keep it coming. I have every intention of taking a humble approach to my venture into track driving. I'm confident in what I have already come to know in terms of cars and more importantly, my ability to drive. However, like with anything, there is always much more to learn.

Here is another question I have been dwelling on. Power steering. Keep it or toss it? I have driven my friends B13 (also destined for the track) which has the power steering removed. There is a lot I liked about the feel of no power steering, but I will admit, there were some situations where I felt it hindered my driving. Perhaps, with time one gets used to it. Any input on the matter?

did he have a non p/s rack?

I recently put in a non p/s rack on my car. Still fairly easy to turn, at low speeds in parking lots I can still steer with one hand. A car with a p/s rack and no p/s is a bitch to turn.

Real engineers and wheel to wheel racers alike all run the UR crank pulley! I wouldn't hesitate!

I asked about HPDE as you will be doing more strenuous driving getting through the HPDE groups ...

I would also highly recommend ducting for the radiator and oil cooler. My water temps dropped about 15 degrees just because of ducting.

did he have a non p/s rack?

I recently put in a non p/s rack on my car. Still fairly easy to turn, at low speeds in parking lots I can still steer with one hand. A car with a p/s rack and no p/s is a bitch to turn.

His car still had the p/s rack, just with all the other p/s components removed. I have heard this is not the best way to do.

I had thought about using a manual rack, but wasn't keen on the longer steering ratio. Thats good to hear that the manual rack makes that big a difference. How is it driving at speed? What bugged me about driving my friends B13 was the excessive torque steer and how much the steering jerked in mid corner bumps. I did feel however, that there were some other issues with the setup of the car that might have caused the harsh steering. Don't get me wrong, I fully expect the added feedback with no power steering, and I expect a little more fight behind the wheel, but what I felt in his car seemed a bit over the top.

Real engineers and wheel to wheel racers alike all run the UR crank pulley! I wouldn't hesitate!

I asked about HPDE as you will be doing more strenuous driving getting through the HPDE groups ...

I would also highly recommend ducting for the radiator and oil cooler. My water temps dropped about 15 degrees just because of ducting.

Thanks for the advice. I think I'll go ahead and pick up a UR pulley along with the gspec WP pulley.

Real engineers and wheel to wheel racers alike all run the UR crank pulley! I wouldn't hesitate!

I asked about HPDE as you will be doing more strenuous driving getting through the HPDE groups ...

I would also highly recommend ducting for the radiator and oil cooler. My water temps dropped about 15 degrees just because of ducting.

+1^ My car has been running with the UR full pulley set for many years, IDK where people get this crank pulley phobia, I have two cars with the same pulley setup. I have run 60 minutes in 80+ deg weather sustained 80+ mph average at NJMP, no cooling issues with pulleys, Koyo, and redline Water Wetter with a 75/25 water/coolant mix. I only use the 25 % coolant for corrosion resistance properties. Oh, and NISMO caps on the rads.

I am a little surprised however my GTi-R radiator isn't so mighty as my Koyo, that car runs consistently hotter. The car with the Koyo also has the front end cut open with the Sunny bumper for max airflow, so that may be it.

Got to get the air in like the man says, I was amazed at how piss poor the airflow was on a USDM stock front end, you've got to open that up.

The license plate holder has been cut out and replaced with a screen for better airflow:

http://www.sr20forum.com/gallery/data/1293/medium/Preflight021.JPG
http://www.sr20forum.com/gallery/data/1512/medium/DSC00262CR.jpg

when you compare that to the stock front end, you have to wonder:

http://www.sr20forum.com/gallery/data/1507/medium/IMGP0912.jpg

Please explain. Are you suggesting I go another route? Right now I was planning on the usual radiator, oil cooler, pulley setup. The only other setup I had put thought to was going with an electric water pump

Glad to see you are well educated on the cooling mods required. What I meant that if it was just one day at the track and you didn't want to spend the money on pullies, you could take it easy (Short shifting and driving short stints) to keep the temps down, but if you are going to beating on it time after time, invest the money.

I think it has been all but proven that the U/R crank pulley is safe to run in race conditions. SR20s in race cars fail because of excessive oil and or water temps or over-revving and not much else.

Glad to see you are well educated on the cooling mods required. What I meant that if it was just one day at the track and you didn't want to spend the money on pullies, you could take it easy (Short shifting and driving short stints) to keep the temps down, but if you are going to beating on it time after time, invest the money.

I think it has been all but proven that the U/R crank pulley is safe to run in race conditions. SR20s in race cars fail because of excessive oil and or water temps or over-revving and not much else.

Yeah, I pretty much have to build this car right from the start. I have every intention of driving this car for what its worth. I gladly toss this car around and put it though it's paces every chance I get, so if it's going to last on the track, it needs to be built with reliability in mind.

Thanks again for the help everyone.

Another side note: As far as oil coolers go, what size should I be looking for? I was looking at Setrab pn#50-125-7612.
Series 1, 25 row, M22 ports
Standard, Air-Cooled Oil Cooler
Fluid Capacity: 0.28 qt (0.26 l)

Is that too large? Would I run into pressure drop issues?

Yeah, I pretty much have to build this car right from the start. I have every intention of driving this car for what its worth. I gladly toss this car around and put it though it's paces every chance I get, so if it's going to last on the track, it needs to be built with reliability in mind.

Thanks again for the help everyone.

Another side note: As far as oil coolers go, what size should I be looking for? I was looking at Setrab pn#50-125-7612.
Series 1, 25 row, M22 ports
Standard, Air-Cooled Oil Cooler
Fluid Capacity: 0.28 qt (0.26 l)

Is that too large? Would I run into pressure drop issues?

I would use the 619 with -10 lines. In order to avoid pressure loss you want to use straight A/N fittings if possible. The less AN bends you use the better, this includes the free flowing constant radius fittings, they cause slight pressure drop. Many times using them is unavoidable, however the ideal setup is as few of them as possible.

If the car is street driven then a thermostat is recommended....

I would use the 619 with -10 lines. In order to avoid pressure loss you want to use straight A/N fittings if possible. The less AN bends you use the better, this includes the free flowing constant radius fittings, they cause slight pressure drop. Many times using them is unavoidable, however the ideal setup is as few of them as possible.

If the car is street driven then a thermostat is recommended....

I had considered the 619 as well. The only reason I ask about the 125 is because I can get one brand new for $80. So, keeping that in mind, is there any reason the 125 won't work?
Is there a benefit to the longer 19 row design, compared to the more square 25 row design. Is it simply a matter of capacity? The 619 hold .40 Qts while the 125 only holds .28 Qts.

As far as the the lines and fittings. I already plan on the -10 lines and I am determined to use nothing tighter then 45° bend fittings. We'll see how that goes.

The only way to know for sure is to give the smaller cooler a try. Honestly though most people are using the 619 or something really close to that. On hot days the smaller cooler may not be up to snuff, but for that price you could always upgrade I it wasn't enough. I simply tend to be a proponent of doing things once.