Change Thompson Filter Relocation to 10an

Roadrunner · Postby **Roadrunner** » Wed Feb 24, 2021 2:14 pm

Hey, so I have a Thompson oil filter relocation kit on my SE and every time I hear people talk about oil lines it's to say "10an minimum" for ideal pressure. The Thompson has 8an lines.
The fittings on the blocks are 3/8NPT. Can I just get a 3/8NPT to 10an adaptor and hook larger lines up or is 3/8NPT smaller than the ID of 10an and would therefore create a 8an sized restriction making the up-sizing of the lines redundant?
AN and NPT I.D measurements make my head hurt.

Lokiel · Postby **Lokiel** » Wed Feb 24, 2021 7:13 pm

https://www.pegasusautoracing.com/document.asp?DocID=TECH00096

TLDR:
Male Thread Size AN Size* Equivalent Tube Size (Nominal OD)
9/16-18 6AN 3/8"
3/4-16 8AN 1/2"
7/8-14 10AN 5/8"
1 1/16-12 12AN 3/4"

The general consensus on MT.net for oil cooling is at least 10-AN hoses or don't bother which eliminates the FM kit and many others.

But if it's just an oil filter relocation key, why not use it as it is?

Lokiel · Postby **Lokiel** » Wed Feb 24, 2021 7:14 pm

Deleted - double post

greenMachine · Postby **greenMachine** » Wed Feb 24, 2021 7:24 pm

So what size are the passages in the kit hardware?

Not much point in putting bigger lines on if the hardware is choking the oil flow ...

Roadrunner · Postby **Roadrunner** » Thu Feb 25, 2021 2:52 pm

Lokiel wrote:
But if it's just an oil filter relocation key, why not use it as it is?

Because as you said, the general consensus on MT.net is at least 10-AN hoses due to pumping losses with smaller hose. Plus the other consideration is that I'll likely be adding an oil cooler in the future and for simplicity I could keep using the Thompson set up and just plumb the cooler into the return line from the filter.

greenMachine wrote:So what size are the passages in the kit hardware?
Not much point in putting bigger lines on if the hardware is choking the oil flow ...

That I have no idea, probably the same size as all relocation blocks, with non of the info available other than the inlet port sizes?
I can only assume that the restriction of the short passages in the block is less than the restriction caused by the length of too small a hose. Which is why I was wondering if I could just put 10an lines on. But I guess a restriction is a restriction no matter how short it is. Probably best to just get new relocation block with larger connections when the time comes for a cooler and just run this as is and stop think so hard about it :lol:

greenMachine · Postby **greenMachine** » Thu Feb 25, 2021 5:02 pm

The Thompson kit has one advantage, in that it catches the drips! So that might be a reason to look into keeping it, and whether it can be modified to improve the flow - ie drilled out. You'd only really need to drill the filter block, the relocation adapter could be replaced with one suited to bigger lines.

I have not heard of actual instances of problems arising from the original kit, but there is no doubt the small lines are a restriction, especially when the oil is cold. If there have been problems, they might have talked about them on the big board, though they used to worship them there and may not have been ready to admit any issues (human nature :roll:

). I have seen nothing on MT.net about them, but then I haven't been looking. In the short term, just don't hit the rev limiter when the oil is cold - which you should not be doing anyway!

:mrgreen:

RS2000 · Postby **RS2000** » Thu Feb 25, 2021 5:30 pm

I'd say use the block you have got. If you use 10AN hoses with it, the 3/8" NPT adaptor will not be a problem due to it's short length.

Luke · Postby **Luke** » Fri Feb 26, 2021 2:28 pm

I had one on my previous SE.
10 years and no issues.
Never even changed the seal once on the block as it never leaked.
That included plenty of track time.
I did not have an oil cooler though and used the lines supplied.

Definitely a major plus of how clean a job it was when changing the filter.
The one(cannot remember brand) on my current SE makes a huge mess each time behind the headlight. Side mounted!!!

greenMachine · Postby **greenMachine** » Wed Mar 10, 2021 7:50 am

Luke wrote:The one(cannot remember brand) on my current SE makes a huge mess each time behind the headlight. Side mounted!!!

Same.

Pro tip: Cut the bottom out of a fruit juice bottle (2/3l), about 2cm from the bottom. Position that under the seal to catch the spill. Job done.

:mrgreen:

Roadrunner · Postby **Roadrunner** » Thu Mar 11, 2021 8:55 am

RS2000 wrote:I'd say use the block you have got. If you use 10AN hoses with it, the 3/8" NPT adaptor will not be a problem due to it's short length.

greenMachine wrote:So what size are the passages in the kit hardware?

These 2 comments got me thinking so i removed the oil filter and measured the I.D of the pipe that the filter spins onto. It's just shy of 12mm. I didn't think to measure the length but it's got to be at least 30mm long - typical fitting length.
That would be the same for any filter block as its determined by the oil filter thread size and this short restriction doesn't effect anything on blocks with 10an inlets.
So yes, when it comes time for an oil cooler, I'll get a new engine side block with 10an fittings, run 10an hose to the Thompson block with a step down to 3/8npt and then 10an to cooler and back to engine.

I'm suprised no one makes a filter block like the Thompson block but with 10an inlets that can be mounted flat on the frame rail. Almost all others are side mounted or raised. The Greddy being the exception but it's mounting bosses aren't right through so needs to be raised up and screwed in from underneith.