321 Motors in non-sealed classes overheating

[DtwSailor]

I overheated twice this season, once in Jesup and once in Constantine this past weekend when trying to run the 321 in 20SSH. Testing continues as I'm not that hot of a driver to have a hot engine although I could think of myself as Smoking Joe Pater Junior!

I was fortunate enough to have the opportunity to run a hot lap on Sunday. I pulled the 321 powerhead that was heating up from the 321 tower and replaced with a 302 powerhead. Same setup, prop as Saturday's heating of the 321. The 302 did heat up as well, so I agree with TJ's thoughts and findings regarding the baffle in the tower.


https://www.apba.org/sites/all/files...0%202016_0.pdf

[DiGia54D]

Dan Parker's 321 overheated at the last NBRA race also

[Dparker]

Yes, been having problems with my 321 in Tabor City, Standish and at the NBRA race in Clarksville, Ark.
Running my entire prop shaft below 3/4" and still over heating.
Have talk to several from east side of the country to the west side including TJ, everyone having the same results.

[Matt Dagostino]

Thanks for posting SORC Chairman Brewster's memo here on Hydroracer...............this is a real issue for drivers wishing to run this engine in CSH/20ssh at the current class heights!

[90M]

I have to add our name to the over heat list at Franklin. I do not have alternative like some others to switch to another motor as we committed to the change from 302 to 321.

[DtwSailor]

I'm going to try to test a 321 powerhead on a 302 tower sooner than later to prove the theory and confirm the findings.

[pav225]

Are 321s overheating in 20ssH or CSH, or both?

[Racerkyle20]

I overheated in CSH at Castle Rock....

[DtwSailor]

I overheated on 20SSH and a new racer next to me was hot coming in from CSH on Saturday. I ran a smidgen below 3/4 on 20 and he was almost an inch on C. I think it's safe to say it's in both.

[Hydro doc]

We may have to lower the height on all classes that the 321 motor is used or redrill the intake hole.

[Ericwienczak]

I also had trouble this weekend with overheating. Didnt seem to be an issue in 300, but it was getting hot very quickly in 20 and C . We even tried running the motor deep way below max height for each class with the same results.

We got concerned so we stopped running the 321 and rigged up the 302

[tim king]

Could it possibly be that the 321 engine is just simply too tight? Because when the 302 first came out they used to overheat also. Maybe we could ask guedo499 how he got his 321 to not overheat. https://hydroracer.net/forums/forum/m...1-321-question

[GrandpaRacer]

The exhaust pathway on a 321 is longer, a lot longer, than a 302. I am guessing therefore the pressure in the tower due to exhaust gas is higher than a 302. That pressure is coupled to the cooling water passages through the Billy hole. It maybe causing a back pressure resisting the forward flow of cooling water. Just a theory.
John Adams

[Joe J]

My 302 runs at 298 degrees ( CHT) in C hydro. My 321 runs at 400 degrees (CHT) in 300 ssh. Obviously something is different.

Joe

[tim king]

Just out of curiosity at what temperature does the motor start steaming ?

[Shane_B]

I set my alarm at 410 F...

[Joe J]

At 400 degrees it is still pumping a strong stream of water out of the dumps.

[Ram4x4]

Out of curiosity, since the 321 was tested by a few folks prior to the decision to let it into 300, was there any heat issue during THAT testing? I don't recall seeing anything about it until recently now that people are getting and running them.

[DtwSailor]

The testing that I conducted last year was with the parity of the 321 with the 302 in the 300SSH class, meaning 2 bladed prop and 1 3/8 height. I can't speak for others. And if they did, we have to confirm it was not just the powerhead being tested but the tower as well. I think that is why it's hit or miss across the country. Those with conversion kits are not changing the tower. just my 2 cents. Of course I'm going to use this whole thing as why I'm not currently high point leader this early in the season...oh wait that's my driving skills....

[jeff55v]

Not to sound condescending, but have any of the overheated engines had their lower units shaped by a reputable person?
I know that correct shaping will increase flow to the water pickups.

[DtwSailor]

I ran 2 separate gear foots from the generosity of Nuncio and Sam Pilato. I trust that they would be shaped in such a way to alleviate that. I hope to do some more testing later this week based on schedules.