engine overheating

[Benno88]

Hi all,
We have a issue with my gen 1 Stohr running a k8gsxr overheating. Currently when racing we are getting 217 deg water temperature.

I'm trying to isolate the issue to being either a problem with flow or the effectiveness of the radiator/problem.

The exit for the radiator on the gen1 is quite small so I'm wondering if anyone has had a flow problem with theirs? (I.e. we're exit constrained) Or if it's another problem all together.

So before I start pulling the system apart and replacing thermostats etc etc or cutting bodywork I'm just seeing if the flow may be a known issue?.

Thanks

[glenn cooper]

Hi Benno - I seem to recall a few of the O1D Stohr's having extended/hooded entry on the front body, to help start the entry of air earlier - like little hoods rivetd on w/ straps to locate. I will see if I can get some pics.
Have you searched on the sportsracer forum?

Are you wet or dry sumped? The reason I ask is I have seen guys run a very wide Peterson "Flower Pot" dry sump tank directly behind the water rad - which to me seems "questionably located"(!), ie blocking the exit flow.

I know it's winter now, these temps were recorded in what type weather?
Is this a recent thing?
Can you hear water bubbling, or puking to the catch tank?
Reason I ask if it's recent and you observe other things like above, are you certain it's running hot, or maybe the data system temp sensor drop down menu has the wrong sensor type selected. I had this happen, so bt,dt!

How old is the rad, that car might be 10 or 11 yrs old.
Fins in good shape?
Totally sealed off?
What size - is there room to go bigger?

Pics of your setup?

Just a few questions/amswers,
Regards, Coops

[Benno88]

Hi Glen thanks for the response.

Ok car is wet dumped and it is a fairly sealed section on the exit side of the radiator, I say fairly sealed as we haven't applied foam to the joins on the bodywork to complely seal it butvtge gaps are minimal.

I think the issue is fairly old it's just not really been picked up on until this year when we are now running 2 seconds a lap faster than last yr.

I think the temp sensor is correct because when we reach 106 deg c the fluid bubbles and burps out to the catch can, so we are running at the absolute to limit on temp. However our oil temp is really low .(another issuse but that's easily fixed)

I'll try post a pic of the radiator but it is quite large in my opinion and very thick.

The weather on the day was about 24deg centrgrade so fairly cold...

[Purple Frog]

On occasion the internal block off plate in the rad header (that separates the top half from the bottom will fail. It is easy to check for with the rad off the car. (I sort of doubt it is your issue, but I have seen it happen)

Have you put a light behind it and attempted to look through to see how open the air passages are?

That rad is thick with a lot of layers of tubes, which is a bit harder to flow air through. But worse if there is debri in between all those inner layers of tubes which you won't see just looking at the outside.

Like Coop said, are the forward facing fins smashed over by debri strikes?

Is your rad pressure cap failing? You can test it with a pressure tester.

[glenn cooper]

Oopsie - I thought you were referring to a Stohr sports racer, hence my O1D model designation.
If you have not already, you can throw out about HALF of what I mentioned...
(This IS the FB/F1000 section, right? Right!!)

When the Stohr FB first came out I remember guys running w/o the complete rear bodywork to test for whether that offered a cooler water temp. I believe it did.
I will call a buddy in my town tomorrow who was driving that car and see what he has to say.

It looks like the car when run the prev year and 2 sec's slower had no issue, so not even gonna mention if there may be a bubble in the system where it might not have bled out correctly, but these cars should be self bleeding, by virtue of having the swirl pot being the highest point of the cooling system...

[ghickman]

No expert on the Stohr FB cars but as I recall Wayne and co. added some scat ducting to flush out high under hood heat in the engine bay. I think these may have been added on at one time?

Something that seems odd to me is that you mentioned your oil temp runs very low. These engines are very much oil cooled as they are water, they have oil squirters behind the pistons to cool them. Kinda rare to see low oil temps but elevated water.

[Benno88]

Thanks for the input guys.

I like the torch idea as I have flushed the veins out before with a hose and noted a lot of sand coming out (my fault beached the car in the kitty litter after touching a white line in the wet...) However I didn't check that I could see through. And it's a quick simple check.

The leading edge of the fins are not damaged or bent.

[vandiemen]

Suzuki's limits for the stock GSXR engine are 120°C (248°F) maximum radiator top tank temperature while using a 123 kPa (17.5 psi) pressure cap and 50/50 antifreeze/water coolant mix. If you're burping water at 106°C (223°F) then your pressure cap may not be holding pressure. We've seen a lot of pressure caps that won't meet their stated pressure rating; caps rated at 20 psi that actually open at ~10 psi when brand new. This can also happen if the filler neck is machined incorrectly and there's insufficient compression of the radiator cap's spring. We've run into that problem, too.

[glenn cooper]

As a quick fix for the above, I have utilised an additional rubber gasket on top of the stock one to add more tension to the spring (Preloaded that bee-otch!)

[James Michael]

You might consider putting flow "slots" in the bodywork behind the radiators on the lower bodywork that has the floors integral. This allows for better air flow through the radiators. When I 1st got my Stohr temperatures were out of sight (230-250) and this solved this issue.
James

[Benno88]

thanks james, i had a close look at the car yesterday and that looked like a really good spot for air to exit. We are testing tomorrow so something i can play with

cheers

[Benno88]

it ended up being 4 small leaks and a lot of blocked parts... will be installing a new radiator this week generally an old radiator...

Thanks guys