Re: My Mk111 Restoration - 136/8620(TBY232L)

[Toby]

Fitted:
New Holley 750cfm
SS headers after wrapping

[colin7673]

I am sorry to ask this question and to some it might be a stupid question, but I really would like to know the answer as I can't work this one out.

'Why would you wrap your headers'

Surely if your headers are unwrapped it would allow the heat to escape, (I know into a hot engine bay), but if you wrapped them, then where does the heat go?

[Toby]

This was done on advice as some of the benifits include a reduction in engine bay heat build up and improved engine performance. There will be those on here who can no doubt provide a more detailed technical explanation of the merits of wrapping or otherwise. Lets see where this question goes?

[Jorrocks]

Pretty sure it increases the scavenging effect of the headers.

[Keith]

Pretty sure it increases the scavenging effect of the headers.

For the benefit of we less technically minded:

Explain please, Mr Jorrocks, first. what scavenging means, and then how wrapping the headers increases this effect? (Especially as wrapping has no effect whatsoever on compression and valve timing).

[Jorrocks]

Who? Me? Oh crap.... Sure I've read somewhere that a higher gas temperature increases gas speed out of the engine. Quote: 'In automotive usage, scavenging is the process of pushing exhausted gas-charge out of the cylinder and drawing in a fresh draught of air or fuel/air mixture for the next cycle'
I understood scavenging to be more of a 'pulling' effect governed by tuned exhaust / expansion chamber dimensions amongst other things. Is that completely wrong?

[RockyUSA]

I would suggest (and the reason I wrapped my exhaust pipe from the manifold to about a foot under the floor of the vehicle) is that you can potentially reduce exhaust heat transfer inside the bay, and shift it to the pipe under the car.

The pipe under the car will typically be in the airstream.

I am certain the overall effect is small.

In addition, I live in a very dry climate, and don't have to worry about the insulating tape soaking up water.

Rocky

[Grant]

scavenging is the process of pushing exhausted gas-charge out of the cylinder and drawing in a fresh draught of air or fuel/air mixture for the next cycle'
I understood scavenging to be more of a 'pulling' effect governed by tuned exhaust / expansion chamber dimensions amongst other things. Is that completely wrong?

Hi Eric .... I think you'l find that scavenging un-burnt fuel and burning it for the second chance/time by the use of tuned exhaust's is more related to the 2 stroke-cycle engine as apposed to the 4 stroke-cycle engine

[Toby]

Rear quarter lights fitted following new seals and re-chroming

[kenny38]

When I had my extractors (headers)fitted I asked about wrapping and the "old" guy told me that the heat dissapation effect would be minimul and use of wrapping would or could cause the headers to rot out. He said in all his years he never was proved wrong especially in Queensland where it is steamy. I had these fitted 25 years or so ago and they are still strong without wrapping. The engine runs cooler and increased power. Kenny38

[Toby]

Windscreen now correctly installed with rechromed trim and new rubber seal from Rejen, delighted with the result no sharp edges to shred your skin. New reed valves to the scuttle drains, the inner arch drain to be trimmed to fit before wheel arch liner fitted

[KaranMK2]

Really good work. Great to see. I also thanked Paul for assisting me with my car.

Karan

[Toby]

Thanks Karan, thankfully there are good people out there only too willing help with these cars

[Toby]

Spare wheel carrier ftted after cleaning and powder coat

[KaranMK2]

A proper job!!! Great stuff and stick with it..it will swell you with pride at the end.