Heat exchanger sizing

[pcatterall]

Still trying to get to grips with this issue. I think my exchanger on my 4108 may need replacing soon so I have started a couple of threads seeking advice.
I now think I am flogging a dead horse trying to repair/replace the old SERK unit so I'm looking at a bolt on universal replacement and accepting that some plumbing alterations will be needed? ASAP offer a Bowman EC 100 as a replacement ( 54 HP engines) but it looks physically much smaller than my Serk. I imagined that the best comparison was to see what the surface area of the cooling tubes was and the Serk worked out at 855sq" ( 0.33"x12"x60tubes x pi) It seems large but I guess it was fitted for a good reason. I cannot find that sort of detail about the bowman product so am at a loss as too what I should be looking for.
have we a 'Mr brain' on this subject please?

 

[Daverw]

There are a number of companies who repair shell and tube heat exchangers for many industrial applications, would be worth speaking to them, retuning is common if you can get the end plates off

 

[LittleSister]

I would imagine that Bowman have been in the game long enough to know how much of what sized tube is needed for what sized engine.

They also seem to do a specific combined manifold/heat exchanger/header tank for the 4108 - Ref No PE108-3483 - if that's of interest. http://www.ejbowman.co.uk/lang/en/products/MarineHeatExchangers.htm

 

[scottie]

Was the Serk properly selected in the first place you refer to fitting a bolt on unit which suggests that it may ot have been.
Bowman do know what they are about.
Many Perkins of that ilk were not produced as marine units but came out of a van etc and marinised so would not all have factory specs.

 

[pcatterall]

Was the Serk properly selected in the first place you refer to fitting a bolt on unit which suggests that it may ot have been.
Bowman do know what they are about.
Many Perkins of that ilk were not produced as marine units but came out of a van etc and marinised so would not all have factory specs.

The existing Serk looks like the one on a previous 4108 and on others that I have seen. It is just held onto the rear of the engine by a stainless SS clamping device.
My first thoughts were just a like for like ( in size terms) replacement with re-plumbing limited to just the connectors. I found an American firm selling simple exchangers ( up to 80hp)
but, again, these seemed small at 500"sq compared to the Serks 855.
As you say the Serk may have been fitted on the basis that too big is safer/better than too small.

I Like that combined header/exhaust/engine cooler( £646) but have no issues with my header or exhaust ( and have good spares) so I will continue looking at just replacing as near like for like as possible.

I would like to just strip down the existing one but as 'my' boat now has multiple owners timing is critical, she cant just be off the road for a long period!

Thanks again