3.9 defender 90 exhaust build advice please

Hi gents.

I have my 3.9 firing nicely now and running as smooth as can be expected without any exhaust.

I was wondering how to go about a build.

I have standard 1990 3.9 RRC headers and downpipes (all fit in nicely) but the 'Y' piece (again RRC) doesnt seem to fit in. It clashes with the transfer box hugely (both correct fitting and upside down).

What have you guys used?

I have a Flowmaster silencer i want to use (from the states) and was planning on fitting this to the Y piece possibly after a bypass valve but time/money and space may be against that.

Can anyone share some knowledge please?

Cheers in advance

Where does the y-pipe hit ?

Take a pic and post it up, can probs modify the existing pipe with a bit of flexi or with a trim and re-weld

I've got tubulars on mine with the round crossmember and ZF auto and have no clearence problems at all. can't tell you the make, they were on the car rusted to buggery when I got it lol

forgive my tardy reply time. Its been p*ssing down here all week and i didnt much fancy trying to fit the exhaust underwater

Ok.

I think i know what's wrong.

The 3.9 Y piece interferes with the transfer box or mount pretty much everywhere.

I have a 3.5 Y piece and that almost crosses the chassis straight across rather than like a true Y (i hope that makes sense?).

So my next question is how will the smaller bore 3.5 Y piece effect the 3.9? If at all really?

I cant photo it as my camera got a little wet (whoops!) so here are some web sourced shots.

There's also a Y pipe for an automatic 3.9 that's different again, it clears the auto gearbox /cross member.

I must have that then as although i have a manual the engine (and exhaust) was donated from a 3.9 auto.

I'll source a 3.9 Manual Y piece and see if that helps (IF the 3.5 one is no good)

3.5 has a smaller flange

richb77 said:

Hi gents.

I have my 3.9 firing nicely now and running as smooth as can be expected without any exhaust.

I was wondering how to go about a build.

I have standard 1990 3.9 RRC headers and downpipes (all fit in nicely) but the 'Y' piece (again RRC) doesnt seem to fit in. It clashes with the transfer box hugely (both correct fitting and upside down).

What have you guys used?

I have a Flowmaster silencer i want to use (from the states) and was planning on fitting this to the Y piece possibly after a bypass valve but time/money and space may be against that.

Can anyone share some knowledge please?

Cheers in advance

Click to expand...

If you want something better than a Flowmaster (i.e., with a better 'snarl' than even Borla) go to Magnaflow (I happen to have a slightly used one with pipe running from the Y back to the tail [I wish I had never taken it off as I think it is superior to the Borla system that I replaced it with])

Wolf

I've also got exactly this problem as y piece hits gearbox mount and goes through where cross member would be will keep a look out to see what the fix is

I have it fixed now.

The fix is simpler than i thought but possibly not ideal.

I have used the 3.5 manual Y piece i have to hand as although its a slightly smaller bore has no apparent impact on the engine performance and with the correct clamps the down pipes clamp it perfectly.

There is a 3.9 (larger bore) manual Y piece available but i wasnt willing to buy another for the sake of the slightly larger bore when as mentioned the 3.5 one seems to be perfectly ok.

As for the flowmaster...Having lived in the US and experienced both flowmaster and Magnaflow, i bought the flowmaster as experience proved them to be a little raspier & better quality (IMO of course).

Lets have a video of how it sounds then

Yes pics & sound:bounce:

I'll try at the weekend. But its a heartache as a sudden change in circumstances have forced me to sell up 95% done

I'm prepping for the new owner this weekend (Family member so not too heartbreaking!)