Exhaust Clearance

[feistl]

Hey guys,

As some of you are aware i am fitting a VT V8 into a FJ40 Landcruiser...

Anyway following on from the general advise from another thread i purchased some 2.5" mandrel bends from Rowville Exhaust and started to build the exhaust system today.

Question is, how much clearance should there be between an exhaust header and a chassis rail? The engine mounts are solid (I think they are standard VN-VT mounts), so shouldn't be as much movement compared to hydraulic filled...

On the passenger side there is plenty (Pics below)

http://i1224.photobucket.com/albums/ee369/feistl/IMG_5442%20Large_zpszjkjnkq9.jpg

But the drivers side is very close. Couldn't measure it, but id say around 5-8mm...

http://i1224.photobucket.com/albums/ee369/feistl/IMG_5471%20Large_zpsyssclzra.jpg

http://i1224.photobucket.com/albums/ee369/feistl/IMG_5477%20Large_zpszsxet9xe.jpg

Question is, is that likely to rub? I obviously dont want to build the entire exhaust system and then find it vibrates/rubs and causes issues.

(Ignore the first weld on the passenger side, i was having lots of problems with the welding rods (Blowing through plus was trying to weld 12 year old mild steel with brand new stainless steel... wasn't easy).

Cheers, Errol.

[IJ.]

Engineers will want a minimum of 10mm, if you find it does touch at that with the stock mounts you can use some type of torque limiter, in the past I've used Limiting mounts, Chain, a Hydraulic damper all with good results, all depends on the room.

[Smitty]

Engineers will want a minimum of 10mm, if you find it does touch at that with the stock mounts you can use some type of torque limiter, in the past I've used Limiting mounts, Chain, a Hydraulic damper all with good results, all depends on the room.

yep.. 10mm is a minimum

[feistl]

Thanks guys,

Would an engineering frown upon putting a 5mm plate between the engine mount and frame? If i raise the engine slightly at the front (heaps of clearance everywhere else) it should give enough clearance for the exhaust....

Edit - Also, does the 10mm clearance include the oil filter? As using the engineered Marks4WD kit the oil filter appears very bloody close to the chassis rail (im guessing around 5-7mm).

Cheers

[feistl]

I can weld the 5mm plate to the engine mount part, and there is more than enough thread on the bolts to fully engage the nuts (even with the spacer)

http://i1224.photobucket.com/albums/ee369/feistl/IMG_5502%20Large_zpsx44h8hrz.jpg

http://i1224.photobucket.com/albums/ee369/feistl/IMG_5496%20Large_zpsw3jhi8f8.jpg

[Thunder]

It is probably too late, but before you custom make extractors you should fit new engine mounts. Those ones look old and probably saggy.
When new engine mounts are fitted, the engine will lift and the new pipes may foul.
A few mm at the engine can correspond to 25mm further back.

[feistl]

Hey mate,

Not too late at all, thanks for the advise.

Those mounts look worse than they actually are... They are a solid rubber style so new ones wont make as much difference as if they were leaking hydraulic ones. But yes, valid point.

Also, (and i had this posted on a few other forums more suited to the 5L V8s) can anyone see an issue with putting an O2 sensor in the collector, then having a balance pipe connect ~2" further down in the first mandrel bend?

Apparently all V8s should have a balance pipe but i cant put it in the usual spot (EG between the cats and mufflers).

Would having a balance pipe so close to the collectors/O2 sensors cause issues?

Cheers

[Thunder]

These engine have lots of torque and stretch rubber engine mounts.
I had brand new 300ZX ones which were $250 each from memory, and looked strong, but we ripped them apart the first day out and ended up with solid alloy blocks.
New mounts may be higher than the old ones, and it pays to have them in first, as it is much easier and cheaper changing mounts than having to redo custom pipes.

A balance pipe isn't essential on a twin system and if you run a single system it isn't needed at all.
Usually on a 4x4 one side has fuel/gas tanks, so a single system is better.

Make sure you leave plenty of room over the front tailshaft as it moves a long way with the front diff when crawling over rocks.

[XUV]

You could put it in a press and squash it, or hit with a sledge, either either ... look under your holden/HSV before you judge