7 replies to this topic

[Dynamo]

After a slight spinkle of rain this morning, this afternoon was bright sunshine, which made for a great day at Spa with Autotrack/LOT. Lots of Porsches, Lamborghini's and Lotuses with a couple of VX220s through in for good measure. Unfortunately fellow VX owner Stu-7 had a mechanical problem with his car today, meaning he can't attend tomorrow. If anyone wants his place and can get to Spa tomorrow, contact him on 07809 198628.

[Stu-7]

After a slight spinkle of rain this morning, this afternoon was bright sunshine, which made for a great day at Spa with Autotrack/LOT. Lots of Porsches, Lamborghini's and Lotuses with a couple of VX220s through in for good measure.

Unfortunately fellow VX owner Stu-7 had a mechanical problem with his car today, meaning he can't attend tomorrow.

If anyone wants his place and can get to Spa tomorrow, contact him on 07809 198628.

Cheers Adrian,
As it turned out, it was a snapped actuator arm.
With the help of GWR (on site) we got it repaired the y'day morning and refitted it to the car but it still wasn't boosting at all so it looks as if the unit has failed completely.
On the way home early yesterday, I had a chat with Mark @ Courtenay and he concurred. Whoever had fitted before I bought the car had fitted it very badly. The actuator arm (pictured below - after refitting y'day am at the circuit) has a brass collar in the middle so it can be extended to fit other cars. You are supposed to screw the 2 bolt-ends securely against each other but in this case there was a big gap and it created a stress point and ultimately failed.



Posted a short review here:
http://www.lotus-on-...ad.php?tid=6690

[siztenboots]

Similar thing happened to me at Castle Combe on Saturday, the lock nut at the top of the threaded shaft came loose, this then allowed the retaining nut at the bottom of the thread to fall off due to vibration, causing my wastegate to stay open. It was fixed with the help of Steve Williams and some new 6mm thread 10mm head pair of nuts from Merlin Motorsport. I now have two nuts at the bottom of the thread locked to each other for additional security. With all the exhaust gas bypassing the impeller via the wastegate, the exhaust has a completely different sound, no overboost, and only 8-9psi at the top end from 4.5krpm onwards , almost vtec like.

[Stu-7]

Similar thing happened to me at Castle Combe on Saturday, the lock nut at the top of the threaded shaft came loose, this then allowed the retaining nut at the bottom of the thread to fall off due to vibration, causing my wastegate to stay open. It was fixed with the help of Steve Williams and some new 6mm thread 10mm head pair of nuts from Merlin Motorsport. I now have two nuts at the bottom of the thread locked to each other for additional security.

With all the exhaust gas bypassing the impeller via the wastegate, the exhaust has a completely different sound, no overboost, and only 8-9psi at the top end from 4.5krpm onwards , almost vtec like.

Interesting.
As soon as it happened my exhaust note dropped about 5 octaves as well. Much deeper. I actually thought the exhaust was blowing it was that bad.
When we refitted the mended arm, nothing changed - it may be too tight, which would explain why the system is boosting, but only at higher revs.

Question - When the arm breaks , or in your case, the nut falls off - I thought the wastegate is subsequently jammed closed, no?

Ie: Exhaust gases > Turbo > turbo spins > system builds pressure > when system reaches a pre determined point (static pressure is about 15psi) the actuator arm opens the wastegate ...........is that right?

[siztenboots]

Similar thing happened to me at Castle Combe on Saturday, the lock nut at the top of the threaded shaft came loose, this then allowed the retaining nut at the bottom of the thread to fall off due to vibration, causing my wastegate to stay open. It was fixed with the help of Steve Williams and some new 6mm thread 10mm head pair of nuts from Merlin Motorsport. I now have two nuts at the bottom of the thread locked to each other for additional security.

With all the exhaust gas bypassing the impeller via the wastegate, the exhaust has a completely different sound, no overboost, and only 8-9psi at the top end from 4.5krpm onwards , almost vtec like.

Interesting.
As soon as it happened my exhaust note dropped about 5 octaves as well. Much deeper. I actually thought the exhaust was blowing it was that bad.
When we refitted the mended arm, nothing changed - it may be too tight, which would explain why the system is boosting, but only at higher revs.

Question - When the arm breaks , or in your case, the nut falls off - I thought the wastegate is subsequently jammed closed, no?

Ie: Exhaust gases > Turbo > turbo spins > system builds pressure > when system reaches a pre determined point (static pressure is about 15psi) the actuator arm opens the wastegate ...........is that right?

Oh yes, forgot about the octaves, it sounded very deep as I crawled down pitlane exit.

I think the wastegate failsafe open by a spring, and this then opens a seperate bypass channel that bypass the impeller, as I at first thought I could hear a whooshing noise, "boost hose come off " i thought, then I realised the exhaust was sounding like it had a hole in it, and I thought maybe the v band had come off the precat to turbo flange.

you adjust it so that when holding the wastegate closed against the spring, you then tighten the top nut and bottom nut to give the actuator a certain amount of preload, on mine it originally had about 6mm of thread left which is factory standard afaik, check with courtenay.

[Stu-7]

Similar thing happened to me at Castle Combe on Saturday, the lock nut at the top of the threaded shaft came loose, this then allowed the retaining nut at the bottom of the thread to fall off due to vibration, causing my wastegate to stay open. It was fixed with the help of Steve Williams and some new 6mm thread 10mm head pair of nuts from Merlin Motorsport. I now have two nuts at the bottom of the thread locked to each other for additional security.

With all the exhaust gas bypassing the impeller via the wastegate, the exhaust has a completely different sound, no overboost, and only 8-9psi at the top end from 4.5krpm onwards , almost vtec like.

Interesting.
As soon as it happened my exhaust note dropped about 5 octaves as well. Much deeper. I actually thought the exhaust was blowing it was that bad.
When we refitted the mended arm, nothing changed - it may be too tight, which would explain why the system is boosting, but only at higher revs.

Question - When the arm breaks , or in your case, the nut falls off - I thought the wastegate is subsequently jammed closed, no?

Ie: Exhaust gases > Turbo > turbo spins > system builds pressure > when system reaches a pre determined point (static pressure is about 15psi) the actuator arm opens the wastegate ...........is that right?

Oh yes, forgot about the octaves, it sounded very deep as I crawled down pitlane exit.

I think the wastegate failsafe open by a spring, and this then opens a seperate bypass channel that bypass the impeller, as I at first thought I could hear a whooshing noise, "boost hose come off " i thought, then I realised the exhaust was sounding like it had a hole in it, and I thought maybe the v band had come off the precat to turbo flange.

you adjust it so that when holding the wastegate closed against the spring, you then tighten the top nut and bottom nut to give the actuator a certain amount of preload, on mine it originally had about 6mm of thread left which is factory standard afaik, check with courtenay.

Ah ok. When you say "impeller" do you mean the poppet valve?

So what you are saying is, as soon as the wastegate detects a lack of preload it will bypass the main poppet valve so that exhaust gas can escape?

[siztenboots]

I meant turbine wheel not impeller. The wastegate channel completely bypasses it , the valve is controlled by the actuator shaft.

[siztenboots]