4722 replies to this topic

[Nev]

@Hairy: Hmmm, EGTs at the head are probably 1000 to 1050 degrees centigrade on full chat, so maybe the inside of the silencer sees a couple of hundred degrees less than that? The mid brown colour of the baffle indicates quite a high temp though I think.

 

@Joe: I didn't have enough large sheets of anything thicker than 1.3mm lying around in the garage yesterday and wanted to finish the job in a day. Also the thing is already quite heavy.

 

@Ditonics: It's all/mainly heat (and cooling) related I think. When I park up I can hear it pinging and crackling to itself. I doubt the lumpy vibration at idle would hurt it, and at mid to high RPM the nasty exhaust pulses are unavoidable (which maybe did contribute, who knows). The baffle is quite large in surface area, maybe a smaller one would stop any harmonics (if there are any). Anyway I still think the main cause is thermal cycles and sheer heat. Inconel (or even lowly 321 stainless steel) might help matters, too late now though! Both the old and the new baffle are 304 stainless steel, (I checked them with magnet too whenever I buy it online). It was all welded with gas coming out of the torch, but not purged.

 

Anyway, took it for a traffic limited test drive today and it was remarkably quiet, probably cos the stuffing is currently is nicely distributed, without doubt it will get noisier as soon as it sees some proper revs and higher temps. I only took it to about 5000 RPM and the pressure gauge showed 0 PSI of back pressure.

 

Seeing as I hadn't been bothered to even drive the car since October I was nicely rewarded, instantly starting on the button and that special electric feeling these cars give you, not to mention the (over?) confidence they give you.

 

Also got to try the new front wheels for the first time, which were a bit more disappointing than I had hoped (in more ways than 1, as the seller knows...)

Edited by Nev, 19 January 2018 - 02:02 PM.

[Nev]

When I was grovelling around under the car the other day I noticed my 5mm thick adjustable stay bar (that holds the central exhaust in position) had snapped due to fatigue. So have fitted a new 8mm one which is a lot more meaty. However, this is only cures the symptoms rather than addressing the main problem, which is the excessive amount of engine twisting/rocking.

 

So I have finally bitten the bullet and ordered up some polyurethane (Shore A70) to beef up the front + rear mounts. I've always wanted to avoid doing this in the past as some movement of the engine is desirable, but in my case I'd prefer to suffer the NVH, faster drive-train wear and snappier "pick-up" than suffer any more turbo flange bolts bursting.

Edited by Nev, 22 January 2018 - 02:10 PM.

[Nev]

This morning I got under the car and pulled the rear engine mount out. I put the mount into a vice and then loaded it up in order to measure the angle of droop (with 3 half inch extension bars and 3 bricks) and hence the approx resistance. This will allow me to do the same once I've poured the polyurethane in and see if the modified engine mount is stiffer than the standard yellow inserts. I thought the yellow insert were pretty stiff TBH, so I'm starting to wonder if I've bought stiff enough PU.
 

 
 
Then I cleaned out the mount with a wire brush + toothbrush + washing up liquid and dried it. Then I made up a gaffer tape seal on one side to hold the liquid resin back and heated it a bit on a radiator.
 

 
 
 
Lastly I mixed up the two-part PU up thoroughly which did aerate a bit with small bubbles and poured it in carefully to try and eliminate any air pockets. I'll  leave it for a couple of hours to semi cure and then another 20 or so hours in the airing cupboard to fully cure.
 

 
 
All in all it took me about 45 mins to do it all. Tomorrow will be the acid test, where I can repeat the bar and brick torque test to see if the chemical bond and new PU is stiffness than the old yellow rubber inserts.
 
The 1 KG pack of PU (Shore A70) cost me £27 on the internet, and I've clearly bought too much.

 

I've never used PU before, it made me feel like The Man in the White Suit (a thought provoking 50's film).

Edited by Nev, 25 January 2018 - 12:15 PM.

[oakmere]

Did you not think about cutting all the rubber out first? I have done the same with tiger seal but was thinking about doing the same as yourself but removing all the rubber first. I think the yellows transfer way more vibration due to the way it wedges in the chassis part of a he mount.

[Nev]

Did you not think about cutting all the rubber out first? I have done the same with tiger seal but was thinking about doing the same as yourself but removing all the rubber first. I think the yellows transfer way more vibration due to the way it wedges in the chassis part of a he mount.

 

Yep, if my current effort doesn't turn out to be tough enough then cutting out all the OEM rubber and re-filling it with PU entirely could be my next step, though I'd have to think about the PU detaching from the bolt tube/guide and then being free to move sideways.

 

Another thought I had is to make 2 discs that act as end caps and weld them to the bolt tube/guide and the cast assembly. Then it would be totally solid, but I think the subframe would be highly stressed by this, so not a good idea.

 

How did you find your Tiger Seal jobby, did it firm it up a good deal, and did it stay in the assembly without detaching or tearing?

 

 

 

Edited by Nev, 26 January 2018 - 09:09 AM.

[Mattias]

Do you have a flexpipe on your exhaust?

[Nev]

Do you have a flexpipe on your exhaust?

 

Yep, a very long one, it's 30 CM, but could be better placed. It's part of the problem, but so is the 420 ft/lb of torque.

 

The original OEM rubber mount is so weak it is startling, hard to believe it would survive 10,000 miles.

[oakmere]

The tiger seal is still in an works well as much more OEM than the yellow inserts but a more direct feel. I didnt do any deflection test before and after though. I found the yellow inserts too much with non std cams.

[Nev]

Been a bit busy out and about today, but popped into the garage briefly this morning to do the bar + brick test. I'm a bit dissapointed as it only seems a bit more resistive than the yellow inserts; maybe something like 20% to 40% more.

 

It's tempting to re-install this and see what difference it's made (by installing my tiny cam in the engine bay and watching the amount the engine rocks). If it's still too much, I might try the same with the front engine mount.

 

Edited by Nev, 26 January 2018 - 03:16 PM.

[The Batman]

Can you post the vid? Will be interesting to see

[Nev]

This is the video I took a few years ago in March 2016 (not 2008 as the camera seems to say).

 

70 MPH pulls in 3rd gear on the low torque map (330 ft/lb) to about 6000 RPM if I remember correctly. Looking at this makes me realise how much the engine lifts at the bulkhead side - I think I might put some resin into that front mount as well.

 

Edited by Nev, 26 January 2018 - 07:04 PM.

[oakmere]

I did both front and rear with the tiger seal with noticeably less vibration than one mound with yellow inserts.

[Nev]

I did both front and rear with the tiger seal with noticeably less vibration than one mound with yellow inserts.

 

I'm not too concerned about the NVH issue, but that's good info for others, I can certainly see why the side contact of the yellow inserts would induce more vibration.  

Edited by Nev, 27 January 2018 - 09:02 AM.

[Nev]

I've put the rear mount back in, waiting for some dry weather to go and test it, with the camera installed in the engine bay if I can remember.

[2-20]

I did both front and rear with the tiger seal with noticeably less vibration than one mound with yellow inserts.

Same thing here.... Less vibrations but the engine seems to move less... With yellow inserts on aft mount i did notice a lot the nvh increase and i felt very little difference regarding " engine response". With 2 sikaflexed mounts it felt improvement in engine response and less vibrations.

Edited by 2-20, 28 January 2018 - 08:25 PM.

[Nev]

Fabulous sunny few hours today so took the car out in the morning. Put the camera in the engine bay and it does seem to be rocking back and forth a little less, though perhaps more than I'd like.

 

I couldn't really detect if the NVH had reduced without the yellow insert, partly due to having barely driven it in 4 months, partly cos the exhaust now sounds different and partly cos there is so much NVH anyway.

 

The exhaust note is quite nice now, the internal changes I made recently seemed to have improved this.

Edited by Nev, 30 January 2018 - 12:51 PM.

[ChrisS1]

You might have met your [straight line] match

[Nev]

Yep, that's Romanian Alex's car, I know him reasonably well and we have helped each other out over the years. His is C20LET based with a GT35, re-built and mapped by himself (as he runs a mapping workshop in Bucharest). It was circa 600 HP last time I heard and up for sale for about 40k euros if anyone is interested.

Edited by Nev, 01 February 2018 - 06:06 PM.

[Nev]

Been out in the black menace and had some fun in the (brief!) sunshine this morning; I seem to be getting the driving bug back a bit. Hopefully Spring will come early this year as I'm quite looking forward to some early morning runs once the sun starts rising earlier.

 

The new front wheels are deffo helping a bit, but will be better once I put the correct sized tyres on them. By coincidence I was talking to one of the Herts M.Sc. race car guys (Alex) on the phone this morning about wheels. He was trying to get some TD 1.2 wheels from them and apparently the company hadn't forgotten that I'd managed to bend one of them very badly on my car some years back. In the end I had to pay cost price for the replacement, but Alex told me they were very close to giving it me for free (but didn't!).

 

When I get back from my holiday I think I'll go up and see their VX220, as it has some interesting developments on it which appeal to me.

 

 

Edited by Nev, 06 February 2018 - 01:29 PM.

[siztenboots]

...

When I get back from my holiday I think I'll go up and see their VX220, as it has some interesting developments on it which appeal to me.

 

I thought their power target was very restrained given the proposed engine work