manifold - how hot ?

woodyracing · 1 Oct 2002, 15:39 (Ref:393150)

anyone know how hot the outside of a manifold gets on a typical hot hatch road car such as an XR2i ?

Also how hot could the radiator get on the outside of the casing ?

Im wondering because I had an air ducting tube which was melting when it was touching the manifold. The ducting is the tough brown race stuff which is rated 700 degrees C (i think). Its the same type and size as what ive seen on Austin Martin race cars.

KC · 1 Oct 2002, 17:03 (Ref:393260)

I presume you mean the exhaust manifold and not the intake manifold temperature. I know on the drag boat I crew cheif we get header temps around 250 degrees F using alcohol for fuel. Gasoline would be higher than that. I would imagine 100 degrees F more would not be uncommon. If you have a lot of valve overlap on your cam it will be higher as more fuel is burning in the exhaust manifold. There are also temp spikes at the bends in the exhaust. More heat is concentrated at the bends in a manifold and header and these can probably exceed the temp resistance of your air duct tubing.
Radiator temp should be near the water temp.

woodyracing · 1 Oct 2002, 18:39 (Ref:393354)

ok thanks, yeah i did mean the exhaust manifold. My new air duct rests on my raditor, it seems ok so far.

MA2 · 2 Oct 2002, 18:39 (Ref:394237)

Depending on how hard the engine is run, how lean the fuel mixture is, and the header material and thickness, temps can easily get up over 1600 F during hard running, with maybe around 6-700 F at idle.

woodyracing · 2 Oct 2002, 23:41 (Ref:394480)

Farrenheit ?

anyone remember the F to C equation ?

**Adam43** · 3 Oct 2002, 08:57 (Ref:394732)

F=C*9/5 + 32

IIRC

THR · 4 Oct 2002, 17:31 (Ref:395915)

the rad wont get that hot.. 100c tops.

the exhaust will get very hot... if you wrap an exhaust in that white insulating stuff itll glow red easily. but will keep your underbonnet temps down a LOT so its really worth doing, and will give ya a few more BHP.
dont let anything touch it just to be safe

woodyracing · 6 Oct 2002, 21:53 (Ref:397145)

cool, i didnt know that stuff glows red. I was going to get some but the sales guy at my local tuning garage talks rubbish and said it wouldn't do much for a road car. Anyway ive done all im going to do on my road car now, apart from my air ducting pipe.

THR · 7 Oct 2002, 11:07 (Ref:397425)

oh.. naa, the actual wrapping stuff dont glow red.. but the pipes do under it.

ISK · 15 Oct 2002, 20:28 (Ref:405162)

Just as a matter of interest... The exhausts of current F1 cars are made of an extremely expensive metal called 'inconel'. At 10,000rpm they glow bright orange. At max power (18,000ish rpm)they have passed through white hot and become translucent. The temperature can exceed 2000 deg C. Steel exhausts would have turned to jelly at this temperature. Cast iron exhasts would have melted ages ago.
Incidentally, when I was doing my training, we had a reliant robin engine strapped into a dyno so that we could put our thermodynamics theory into practice. we calculated that the engine gave about 48 hp, but even the manifold on that used to glow red when we ran at max power.

THR · 16 Oct 2002, 15:25 (Ref:405801)

u watched the prog on discovery channel to then!

JR Ewing · 16 Oct 2002, 15:54 (Ref:405825)

Quote:

Originally posted by woodyracing
cool, i didnt know that stuff glows red. I was going to get some but the sales guy at my local tuning garage talks rubbish and said it wouldn't do much for a road car. Anyway ive done all im going to do on my road car now, apart from my air ducting pipe.

Sounds to me like the only honest such person there is.

There is no way you can tell the difference on the road.

This reminds me of the Splitfire advertising furore when they showed a picture with two sparks and insisted it happened that way and then looked bl**dy stupid in court when it was pointed out that it was a physical impossibility!!

Most (if not all) Max Power type addons are absolute ****e, eg. Fuel power valves, hi-tech plug leads, exhausts.
Most reduce power!!

woodyracing · 16 Oct 2002, 17:58 (Ref:405942)

umm, i have Splitfire plugs, uprated HT leads, stainless exhaust, superchipped etc etc. The rolling road showed the 'max' power has gone from 120bhp to 150bhp and its definatly quicker (not a huge amount though).

The power band has moved into the higher rev range though so its pretty docile at low revs. A lot of revs are needed before it gets a good power surge. ( i think this is mostly caused by the exhaust system )

As for exhaust insulation wrap, they claim to reduce under bonnet temp by 90% (i think) and since i have a free flow air filter which sucks air from under the bonnet (and my cold air pipe now) it must reduce induction temp, hence more power. My car is certainly much faster when the outside temp is cooler like in winter.

JR Ewing · 17 Oct 2002, 08:20 (Ref:406306)

The chip and the exhaust will be having the effect. Splitfires!!
But really all you doing is moving the power curve around.
The chip can overfuel (economy will go down) but your engine will be limited by the air it can get in. the filter will help a bit but you are constricted by the inlet manifold.
Is your XR2i a Zetec or the CVH, which has an adjustable fuel pressure regulator as standard fir from the factory?

woodyracing · 17 Oct 2002, 09:21 (Ref:406339)

Its a Zetec. I asked about an uprated fuel regulator (an FSE 'power boost valve') but they said i wouldn't need one since i had the chip fitted.

boyracer · 22 Oct 2002, 07:23 (Ref:409960)

Just a note on the exhaust insulation wrap.
Certainly good for under bonnet temps. and on a car with the intake manifold siiting directly above, even better.
However this does appear to have an adverse affect on the metal structure of the extractors that you wrap up. The repeated heat cycles, along with the increased magnitude of the heat cycles (due to the insulation stopping the pipe radiating a large % of the heat) the metal actually starts to harden and thus become more brittle.
Have had this happen to a friends car. The extractors got so brittle that they started to crack.
Nothing more from this post, just letting you know that there are always 2 sides to the story.

THR · 22 Oct 2002, 11:40 (Ref:410119)

didnt think about that...
outta interest, do u know wot it was made out of? stainless, carbon, steel?

boyracer · 24 Oct 2002, 03:42 (Ref:411839)

Was carbon steel, however would probably happen with stainless as well. Though stainless has higher melting point (?) would probably happen to a lesser extent.

THR · 24 Oct 2002, 11:53 (Ref:412051)

Stainless is stronger, right git to machine! so i guess that would help things a bit.
It might happen to that too tho! not sure.

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