me and my evans:


this is actually a very long story with many twists that i will condence to the important nuggests of info :-) ......

So Im at the local track droppin the hammer on the yellow monster track car and after the first few laps the car trips out a little bit during a wOT straight, I pull in.... cant find anything wrong, but everyone tells me they smell coolant... im like , hmmm, no overheating, no coolant light... well lets check for coolant blow by under the car...

AHHHHH!!!!!!

coolant is all over under side of the car, on the right side of the engine bay by spark plugs... I'm freaking out, we jack the car up and search, cant find the dam leak source, its not leaking at idle or by revving.... we clean it up and I go out again to get cooloant to come out.... come back after on 1 lap and coolant all over the same post again....I and 2 other mechs are stumped, we tried fixing a hose, a sensor, a quick-disconnect coupler, all to no avail, ...it still leaked after 1 lap on each fix. :-(

I though, ****, this is it, the yellow monster id down for the count, it must be leaking on the hard lap because compression is forcing coolant out of a seal that blew on the engine housing.... its all over :-(

..but an expert mech, Matt Litchfeild, helped me to find the culprit of the leak, and neither of us were convinced it was the engine yet... so...

we got it to a lift and hooked a presure tested to it, bamb!!!... coolant just dumping out, but on the OTHER side of the engine bay where we saw it on the track!!! ??? WTF???... nothing is coming from that side anymore, instead its spewing from under the intake manifold on teh LEFT side??? so we take the UIM off and start to dig, .............BOOOYAAAA.... its a stupid 50cent rubber cap that capped the nipple on the engien bay that would normally goto the throttle body coolant line on a stock car. OMG!!!! was I relieved... we plugged it up with a high end fuel hose/bolt/clamp and put it back together, it ran fine, no leaks anywhere and I went back the next day to the track (it was a 2 day event) and whopped *** on my previous times, gettin the fastest time of the day in the second session ( http://www.aarrf.com/results/index.asp ).

so 2 big things to note here on coolant pressure:

First, one of the reasons the leak was hard to find is that I run evans at ZERO pressure, so at idle the coolant will not be forced out of a crack that is not big enough to let coolant by without some pressure.

Second and more importantly, RUNNING EVANS MAY HAVE SAVED MY ENGINE simply because a normal coolant setup would have instantly lost its boiling point capacity once the leak started, i could have overheated and cooked the engine during a hot lapping session, while focused on driving. Evans, on the other hand, has a rediculous boiling point even under zero pressure, so although I had a leak the coolant never changed temp because of it, keeping the engine safe...obviously if the leak was bad enough to draing the coolant so much that it cant transfer heat, then all bets are off, ...my leak was minimal, so much so that it never even got to the 'coolant light' level before I noticed.

...anyway, I am not saying for people to go one way or another, but i can say that I like evans for many reasons...so far.... it takes years of use to really know.

2)

 

Good deal. It could have been sooooo much worse.

 

yeah, could have been trajic so im happy it was nothin.

 

so the cap determines pressure? i.e, you use a 16lb cap, will it pressurize the evans? I'm running the AST elimination filler neck top thingy, it comes with a 16lb cap i believe, would that be appropriate to run w/ evans?

 

You can run NPG+ with or without pressure. With pressure it has even higher boiling point, but why would you need to. All pressure caps can be modified to run 0 pressure, just remove the rubber seal.

 

good point, was just asking how it reacted to be pressurized i guess...

 

Sold me, Damian. Good job!

 

I don't know if a pressure cap will increase the boiling point but it's great at keeping the funky coolant smell out of your garage.

I run a 7 psi cap initially to get rid of any water residual. Ended up keeping it on.

Cost is a concern but hell after you've lost 2 motors to coolant seals every 50K, you'll try anything.

Operating characteristics are different than standard mix. I changed my PFC ignition retard temp b/c I would see 240 in traffic with AC going full blast on a 90F day. KS Vented hood coming soon.

Haven't checked the oil temperature but is thinking about a second oil cooler or a larger main cooler.

 

Did you do this through the PFC Commander keypad or through an FC Datalogit? What temp did you choose for the Power FC to begin ignition retard?

 

Via Datalogit. My car hasn't seen track yet so I've set it for 115C. If I put it on the track, I'll probably go 120C. Set fans to run at 195 F.

Running AC will add 10 to 15F degrees on top of normal temp.

Running w/o the rear seals b/w the hood and firewall will add 10-20 degrees the faster you go.

It's been close to a year now and my coolant voltage measured with a probe in the coolant and another probe on the alternator ground still shows 0.08V. EG and W would show 0.13 to 0.2 volts.

When I first started my car, I had built my own AST. What I didn't realized was that there is a restrictor in the line at the bottom of the stock AST. So coolant basically bypassed the upper 2 inch rad hose and went through the 3/8 in. AST hose. The coolant temp went up to 260 at the filler neck but my stock gauge never moved. This was a year ago. No ill effect that I could see.

 

Ahh, FC Datalogit! With the Evans NPG+, GReddy FMIC/Koyo rad, I'll probably set Power FC to 130 C (266 F) before ignition begins to retard. Thanks.

 

yes, the cap determines pressure.
you can run the 16lbs cap with evans but you would be pressurizing the system for no reason, adding stress to the cooling system that is uneeed

 

hehehe :-)

well, thanks me after it all work out well and you can race all day with no cooling issues...then I'll take the 'good job' :-)

 

yeah, i need to check my cars on this too and reset the retard temp if needed.

 

You run 0psi on your daily driver damian? How about on the track car? Where can I get this 7lb cap?

 

Update coming after Labor Day @ Mid Ohio

 

Poman, where were you able to find a 7psi cap? I've found it difficult to source a low pressure cap.

 

These things amaze me. People are so quick to get rid of the throttle body coolant lines as a "reliability mod" and so they remove the hoses and then replace them with something that is still rubber If anyone is going to do stuff like this the proper way it to remove the entire nipple and put a pipe plug in there. Otherwise you're just fooling yourself.

damian, I know you didn't build the car

 

I don't have tye OEM cap as I'm using a Canton coolant reservoir ($69.00) with the standard large radiator cap. If you're using Pettit or the RX7 store AST, you should be able to use these standard caps.

 

I bypassed the throttle body completely with a hose that connects the outlet from the block to the nipple on the rats nest. Reason for this was the pain in the *** it took every time I removed the TB, I had to remove the coolant line. Be aware that there is a cold idle with a wax pellet that regulates your idle, which will cause your idle to fluctuate in cold weather.

 

So you kept the hose and now have a poor idle when it's cold. How's that not a step backwards? You remove your throttle body every weekend?

 

I've been trying to chase down this fuel smell so yeah the TB is off every other weekend.

Idle can be adjusted via Datalogit maps.

 

I thought this was really more of a power mod (trace amounts), vs reliability.

It is ok to use a short length of reinforced SAE rubber hose, with a metal plug, and hose clamps. Pipe plug method is most reliable.

It's not ok to use a blister pack vacuum cap from pepboys, made from unreinforced rubber, and designed for dry vacuum use only. And don't use these when eliminating the AST.

 

I just ran a line from the nipple on the back side of the block to the nipple on the back side of the water pump. Worked fine. The only reason I did this "mod" was so I could pull the uim and tb off faster.

STEPHEN

 

Most, mods are done poorly and end up not doing anything but reducing reliability.

Damian, I know you didn't build the car also.

I've seen so many reliability mods that have failed it really makes me wonder what people are thinking when they mod the car...