UK-POLOS.NET - THE VW Polo Forum

how much would i need to wrap a manifold?

Why do you want to do it?

You will collect too much heat in the headers and overheat the valves...unless you have a tuned engine...


Its utterly pointless given the flow of air over them keeping them cool!

don't no a great deal about engines, but i thought that this was a good thing to do to a manifold?

I was wondering about this too. Is the raceland manifold ok in the GTI engine bay? The original has a heatshield but I assume it doesn't fit with the raceland

I'd also like an explanation of why it's bad - I thought it kept hot air out of the engine bay and out the back of the car instead.

Yes, the theory is that the wrap keeps the heat inside the exhaust so that more of the hot gasses are passed out of the back of the car rather than allowed to heat up the engine bay.....

It is also added in some instances to reduce underbonnet temperatures and prevent damage to anything else....so in my kit car, the headers are wrapped to prevent the exhausts melting the brake servo....


However... My understanding is that, adding wrap to the headers can significantly increase the temperature of the exhaust ports on the engine causing all sorts of prolems on an engine that is designed to run with cool exhaust valves....Unless you are going to remap the engine to allow for this increase in exhaust temperature...its not a brilliant idea!

You may also damage the cat if you increase the exhaust gas temperature too much, and also give eroneos readings from the o2 sensors...


I can see douzens of reasons against it, and none for....Your engine bay doesnt get that hot with a standard exhaust because there is good airflow when the car is moving...



An interesting point to note is that, standard mild steel exhausts conduct heat better than stainless steel ones, so a standard exhaust would in theory get hotter on the outside...... But given that most stainless steel pipes are large diameter than the mild steel alternative, they flow more air and therefore keep cooler...


You wont get a power gain from adding the wrap, you wont really make much odds to the underbonnet temperature (and anyway, whats wrong with a warm engine bay?)....

If its bling factor you want, there are safer ways to get bling points

Word.

seriously ppl go out and buy a book called how 2 tune ohc engine! its in hallfords and most book shops and its a rearly good read " not overly complicated ither!

But 2 answer your question yes heat wrap is good cramice (cant spell) coating is even better! Hot air moves faster than slow air FACT this helps a thing called scaviging (were both the inlet and exhaust valves are open at the same time) helping 2 draw more air and fuel into the cylinders ( bit like a vacume! more air more fuel bigger BANG faster polo gti! lol

No 2 answer some of the rather odd things people have posted!
1) no it wont burn out the valves infact the oppersit it helps 2 cool the valves by pulling more cold air into the cylinders on each stroke and by getting the hot exhaust gasses out quicker!

2) The lamba probe / o2 sensor will be fine in fact it helps! O2 sensors r designed 2 work 2 stupid temps (cant rember the figer off my head) just look at big 600 hp cosworth (were i spend the other half of my time) they put 02 sensors cms behind the turbo 2 aid mapping and these turbos get so hot the go seethough! (seriously look on u tube it will take ur breath away) and they dont fail every 2 mins! hOW IT HELPs !! At vw we change hundreds of 02 sensors biggest fault we have and 99% of these r down 2 carbon building up on the sensor faces causing them 2 fail! this is down 2 the amount of people who use there cars only for short trips not alowing the exhaust 2 get hot anothe 2 burn of the carbon deposits! see when this is going lol hot exhaust = clean exhaust !! happy polo gti

3) cats burning out this rearly made me lauf! cats dont start working till they are stupidly hot like take ur skin off! infact thats the basics of how they work get hot then burn the nastys that are left over in the combustion process!
So a hotter cat = a more efficient cat this nastys dumped into the atmosphire!
And i nearly forgot alot of faliurs on cats r due 2 carbon build up! infact i once bought a 6n polo cheep cos it would start then cut out! after a bit of digging i traced it 2 a blocked cat so full of carbon the exhaust couldnt get though! so i disconected the exhaust and she ran perfectly (just VERY nosiy lol)

Any other things u like me 2 explain if i know i will!
Hope this helps now get wrapping! lol

o and sorry about my spelling not my stong point but i hope u all get the jist!

It really depends what you read......Cant be arsed to get into an argument over it...

You can make your own decisions wether is good or bad for your engine, car etc...

But IMHO its not going to provide any improvement whatever to a standard(ish) NA engine.....

What ive read! lol
Dont think i got all that out of one 10quid book do u? lol (othough the book is rearly good if anybody wants 2 learn about this sort of thing!) try 5 years at collage- uni studding (not spelling though lol) then 4 years training at vw!

Never said it will give him more proformance chances r he wont even notice it! but will it emprove the efficiancy of his engine, give him a longer lasting exhaust system, help him lower his cars emissions maby even increse his mpg. yes it will! Not by any massive increse but anothe 2 warant paying £15 quid on some wrap!

And sorry i missed were u got your infomation from??

Also if this is an aftermarket stainless steel manifold like the Raceland that we are talking about, exhaust wrap will cut down on, if not eliminate, the ticking that they sometimes produce. Just ask olop_chris or iceypolo!