Blocking off the hose to the Wastegate on a Tdi300?

[Robmacca]

Gents....


A while ago a mate tweaked up my IP on my Defender and when I took it for a drive up a certain hill that I always use, I noticed that the boost had increased and now getting up to a MAX of around 19>20psi as per the boost gauge + it drove/responded much better - no problems...


Recently we had to remove the Turbo & Exhaust manifold off my engine so we could swap out a suspect Starter Motor (I've got a Non-Gen Mitsi Water/Oil Cooled Turbo). When we removed the Turbo we noticed that the wastegate lever was really stiff to the point that I doubt it was working. Anyhow, we freed the lever up so it was moving freely and re-assembled everything & I drove home. I went for a run up the same hill as before and noticed that the boost only really got to 15-16 psi this time. So I was thinking that maybe the wastegate had never been working before. To confirm my thinking, I did a little test in that I blocked off the hose to the wastegate and took it for a run up the usual hill and to my surprise, the boost was back up to 19-20psi.


My question is: If I was to block off the hose to the wastegate permanently, would I end up doing any damage to my engine?


The boost never goes over 20psi and it seems to drive/respond better with the hose blocked - Is it ok to leave the hose blocked off?




rob

[BigBlackDog]

The wastegate OPENs to let excess exhaust flow bypass the turbo, it is held CLOSED and pressure from the boost side controls it. Blocking the flow is essentially all a boost T does, by turning the T boost up it restricts the pressure into the wastegate control 'tricking' into providing more boost.
What you have is a normal functioning 300tdi turbo now, they are only meant to output 14 or 15psi factory, and that is what the turbo is designed around. I've been told by a reputable Land Rover fella that 18 is safe. The turbo only has a oil line bearing, so no rollers etc. I've seen replacement cartridges from the uk that they say are safe to 22 but on roller ball bearings (or similar) remember more boost equals more turbo rpm equals more wear. Running without the line also equals no protection, but maybe that doesn't really matter on a 300tdi

sorry missed the statement about non standard turbo. People seem to suggest over tensioning the head bolts when running more boost like a VNT turbo.

[Robmacca]

The wastegate OPENs to let excess exhaust flow bypass the turbo, it is held CLOSED and pressure from the boost side controls it. Blocking the flow is essentially all a boost T does, by turning the T boost up it restricts the pressure into the wastegate control 'tricking' into providing more boost.
What you have is a normal functioning 300tdi turbo now, they are only meant to output 14 or 15psi factory, and that is what the turbo is designed around. I've been told by a reputable Land Rover fella that 18 is safe. The turbo only has a oil line bearing, so no rollers etc. I've seen replacement cartridges from the uk that they say are safe to 22 but on roller ball bearings (or similar) remember more boost equals more turbo rpm equals more wear. Running without the line also equals no protection, but maybe that doesn't really matter on a 300tdi

sorry missed the statement about non standard turbo. People seem to suggest over tensioning the head bolts when running more boost like a VNT turbo.

Under normal driving, the boost is within normal range, its only when pushing hard up long hills but in saying that the egt's remain within limits.....

[SSmith]

With the wastegate closed it may choke it at higher revs, mine did under similar circumstances, but a different turbo.

It will, of course, shorten the life of the motor running it at higher boost but most say 18 - 20 psi (as long as EGT's stay within limits) the harm is minimal.

[Toxic_Avenger]

What turbo is fitted to the tdi300 from factory?
It would be an interesting thought exercise to look at a compressor map of this turbo and see what wiggle room there is with the pressure ratio, turbo efficiency islands and surge lines.

[Robmacca]

With the wastegate closed it may choke it at higher revs, mine did under similar circumstances, but a different turbo.

It will, of course, shorten the life of the motor running it at higher boost but most say 18 - 20 psi (as long as EGT's stay within limits) the harm is minimal.

Heading away this weekend so it will be a good time to see how it goes. As I said u really need to push it hard to get it to go above 17psi and that’s something that I try not to do very often.

[SSmith]

What turbo is fitted to the tdi300 from factory?
It would be an interesting thought exercise to look at a compressor map of this turbo and see what wiggle room there is with the pressure ratio, turbo efficiency islands and surge lines.Garret something (google it later) was stock on 300tdi

Mitsubishi TD04 iirc, was a common substitute before vnt/vgt became affordable. This is possibly what is fitted.

But right you are, curious.

[SSmith]

Heading away this weekend so it will be a good time to see how it goes. As I said u really need to push it hard to get it to go above 17psi and that’s something that I try not to do very often.Worth a try.
If it turns out that you are right, and it ran for a while without a properly functioning wastegate, then it cant be doing too much harm.

[Toxic_Avenger]

Garret something (google it later) was stock on 300tdi

Mitsubishi TD04 iirc, was a common substitute before vnt/vgt became affordable. This is possibly what is fitted.

But right you are, curious.

Wikipedia (Great source!) suggests an Allied Signal T25 Turbocharger. Allied signal is a Garrett brand iirc.

Rather than reinvent the (turbo) wheel, there is some great info in this thread (https://www.aulro.com/afvb/projects-and-tutorials/96492-300-tdi-td5-turbo-upgrade-post1159840.html#post1159840)too.

[rick130]

T250-04, off the top of my head.

The MHI TD04 is a much nicer, newer generation version.
MTQ use this in their Tdi updates.

Have the wheel specs for the Garrett somewhere


Oh, and a bit more boost with an MLS head gasket shouldn't be an issue.
I'm unconvinced on overtensioning the head although John/Bush65 suggested it, but that was when we all later the composite HG.
I'd be more inclined to just use an AMC head and the MLS head gasket and bump the boost up to 19psi or so.

[DiscoMick]

Don't block it. It is needed under extreme conditions.