4722 replies to this topic

[Nev]

Got to do some little jobs today:

 

1. Tidy up the garage, it is absolutely filthy with metal dust everywhere.

2. Invent some sort of shield to go over the butterfly flap bush, as it won't like dirt going into it.

3. Check for witness marks of any pinprick leaks.

4. Lower the exhaust brackets by about 2mm each to get the box to stop clunking.

5. Invent some way to stop the silencer moving slightly from side to side.

 

 

Edited by Nev, 17 March 2017 - 09:04 AM.

[Nev]

Got to do some little jobs today:

 

1. Tidy up the garage, it is absolutely filthy with metal dust everywhere.

2. Invent some sort of shield to go over the butterfly flap bush, as it won't like dirt going into it.

3. Check for witness marks of any pinprick leaks.

4. Lower the exhaust brackets by about 2mm each to get the box to stop clunking.

5. Invent some way to stop the silencer moving slightly from side to side.

 

 

 

[fezzasus]

I recall the original exhaust having a welded washer (or similar) on the exhaust hanger so stop horizontal movement of the box. however looks like you've already addressed it

Edited by fezzasus, 17 March 2017 - 02:01 PM.

[Nev]

I recall the original exhaust having a welded washer (or similar) on the exhaust hanger so stop horizontal movement of the box. however looks like you've already addressed it

 

I looked at it for 30 seconds this morning and did much the same, by installing some washer spacers on the hangers. All sorted now.

 

There were a few minor sooty witness marks from a couple of leaks but nothing that couldn't wait for a year or 2 when I next take it off for some reason.

 

I think I will chop another CM off the tailpipes as they seem to be sticking out a bit, but I need to buy my own linisher first to clean up and square the ends.

 

All in all, the job is done now, pretty sure it will scrape under the 105 dB static noise check at Castle Coombe. Hopefully the high rev noise will be safe too, especially if I install a 90 degree tailpipe bend (pointing away from the trackside microphone) as Joe suggested.  

Edited by Nev, 17 March 2017 - 02:07 PM.

[ditonics]

My full 3" Tullet system with a baby sports cat weighs 15.8Kg for your reference.

That's turbo to tip.

 

Edited by ditonics, 17 March 2017 - 02:16 PM.

[CocoPops]

93 dB(A) and 100 dB© at idle. Once on the power you can hear the effect when the valve opens up. It's liberated the 50 or 70 odd HP (that I guess) was lost from the last silencer.

All in all, the job is done now, pretty sure it will scrape under the 105 dB static noise check at Castle Coombe.

Static is done at 3/4 max revs, so although your idle is under, is 3/4 max revs really only going to add 5dB?

[Nev]

My full 3" Tullet system with a baby sports cat weighs 15.8Kg for your reference.

That's turbo to tip.

 

Thanks for that Simon.

 

I would guess my downpipe to the silencer is about 8 Kg, so my whole new system weight would be around the 21 Kg mark. So 16 Kg vs 21 Kg isn't quite as much of an increase as I thought.

 

At the end of the day it means I can at least drive around without annoying my neighbours so much and get on the occasional track day hopefully. Also, it attracts less attention on the road which will help reduce how many stares I get. I still remember being followed closely by a police car for about 15 miles last year through a load of villages, whilst I tried to nurse it along at 30 MPH and kangarooing in high gears to keep the noise down.  

Edited by Nev, 17 March 2017 - 02:17 PM.

[The Batman]

Just lie. I say mine only revs to 6.8k

Edited by The Batman, 17 March 2017 - 02:15 PM.

[ditonics]

lie is the way forwards, my gauge has a red line at 6500 so thats my limit isn't it Mr Marshal. 

[Nev]

Just lie. I say mine only revs to 6.8k

 

Indeed, it's funny but every time I've had a noise test at CC they only ever asked me to rev it to 4500 RPM. If they ask what the max revs are I'll just say 6000 where the OEM setup fizzles out.

 

In fact I could get the laptop out in 60 secs and set the hard limit to 6000 (or whatever) and then demonstrate it to them. And then switch it back to 8000. I could also release my counter-opposing spring, so the valve will be totally closed at 4500 RPM for max silence, this is one of the key advantages of a dynamic silencer.

Edited by Nev, 17 March 2017 - 02:23 PM.

[Nev]

Just been out for a second test of the exhaust and managed to heat the bulkhead up so badly that the rivnuts have all melted out and my metal baffle plate fell out.

 

This has happened because I still haven't re-wrapped the stupid exhaust manifold after it had a weld failure last year. I badly need to do this in order to get engine bay temps down before I drive it tomorrow morning.

 

On a plus note though, I took the engine upto 6000 RPM and only registered 1 PSI of backpressure, a nice success in that respect.

Edited by Nev, 18 March 2017 - 06:25 PM.

[ditonics]

Stuff some old nimbus round it as a temp measure while your do your testing. If you have some lying round that is.

[Nev]

Stuff some old nimbus round it as a temp measure while your do your testing. If you have some lying round that is.

 

I have loads of Nimbus, but unfortunately all that does is point the heat back into the engine bay once it's already escaped. I really need to stop the heat getting out of the manifold to start with. Wrap is amazingly cost effective at doing this IMO - very under-rated stuff.

 

Will put some gloves on and do it tonight, though it will be yet another awkward job I don't look forward to.  

Edited by Nev, 18 March 2017 - 06:08 PM.

[Mopeytitan]

For testing can you not make a sort of chute for it to almost direct it out of the engine cover?...

[The Batman]

What exhaust stuffing did you use? Just wondering if that can handle the extra heat form a wrapped manifold

[Nev]

For testing can you not make a sort of chute for it to almost direct it out of the engine cover?...

 

Hmm, the OEM one has this sort of setup, but it's not all that effective in my engine bay as I have huge amount of fresh air turbulence (mainly from underneath where the floorpan is currently removed), so the hot air gets blown about before it gets to rise upwards.

[Nev]

What exhaust stuffing did you use? Just wondering if that can handle the extra heat form a wrapped manifold

 

Mainly stainless steel swarf/cleaning pads, hopefully that wont melt!

 

But also used a bit of normal glass wadding which will brittle up fairly quickly I expect.

 

If it requires it, I can alway cut the silencer open, restuff it and weld it up again.  

Edited by Nev, 18 March 2017 - 06:33 PM.

[CocoPops]

What about a reverse idea? Snorkel above the roll hoop, forcing air down past the manifold and out under the diffuser area? Would need channeling but would cool the air around manifold and then send it out the back.

[Mopeytitan]

I was thinking the same but from under, so grabbing air from under the car directing it upwards past the turbo and manifold out the top

[Nev]

I was thinking the same but from under, so grabbing air from under the car directing it upwards past the turbo and manifold out the top

 

Quite a novel idea, I like it, but I am working with some MSc auto guys from Hertfordshire Uni on an under car project at the moment, which stops me from doing that.