What size restrictor is everyone using in the thermostat housing to slow down water flow and keep it in the radiator longer to cool it? Was planning to gut the thermostat and weld a washer in but not sure what size hole. Running a GSXR-1000.

All we have done for the past several years is cut the spring and plunger out of the unit and use the existing hole that is already there. Works just fine for us ,takes a little longer to warm up but much easier to ensure there's no air in the cooling system .

Not meaning to hijack this...ok...I am. Haha. But I'm running an Afco radiator in my ERC Lightning sprint. 2008 R1 on methanol. Not sure what's happening but there are no leaks. Ran hot laps last night, no issues...then came in from heat race and it was up to 245 and steam coming from overflow tube. Let it cool and checked coolant, and I lost maybe a half quart or so? It was full and bled of air before the night began. What's happening? Anyone got any ideas?!

Never had issues with it getting hot until last couple races last year. Like I said, no visible leaks anywhere.

Slowpoke,

Most of us run either a 5/8" restrictor, or simply use -12AN hose and fittings.

cmi...,

Can be really tough bleeding all the air out of the system sometimes. I have a funnel which attaches to my radiator neck with a special cap so no air can get in. I fill it up after the system is full, then bleed the lines in a couple of different places with the motor running. Then let the motor run and get up to temperature. If there is still air in the system, the temp will gradually go up to around 210-220, then it will spike very quickly, and probably be a lot of bubbling in the funnel at the same time. That means you still got air trapped somewhere. If nothing drastic happens above 220, then turn the cooling fan on to cool it back down, and you should be good. I leave the funnel filled with coolant on the radiator till the system is stone cold again before I remove it and put the cap on.

Bill, where does somebody get a funnel like that, or did you fab it yourself? Got any pics?

You can also buy a tool called an "Air Lift" that vacuum's the air out of the system before you fill it. We use this tool on cars at the shop all of the time and it works good too. I originally started this thread to get an idea on what most were using to slow the flow thru the radiator and based on all of the personal messages I have received as well as the post put up here it looks like 5/8 hole is the most common size that works. Thanks for the info guys.

Jim,

It's called a Lisle Spill-Free Funnel. Part #24610. About $25 on Amazon, but might be available in a local automotive store.

Bill

Nice setup; it's even in my color!

Thank you! I must have air in there somewhere. Found that funnel at Oreillys. It was 39.99 though. Comes with multiple attachments and a nice plug feature for saving unused coolant.

I bet it was it a pretty hot day??? You can cool these things with Methanol also. Just bump up the fuel pres about 4 or 5 PSI. See how it runs. The radiators are kind of small for these cars so we also use a coolant recovery system on ours. Take a Lucas or other plastic 1 quart bottle and zip tie it to your frame just behind the radiator, run the overflow tube cut at a 45 degree angle to the bottom of the bottle. When the radiator heats up the coolant expands into the bottle and then when it cools the radiator creates a vacuum and draws it back into the radiator a lot of times even during the race.

You must be pushing her pretty hard now because this problem usually doesn't exist until you start really getting with the program.

Honest Dad himself