Seems that people think removal of the heat shield on the top of the OE manifold causes the hood paint to have problems. I removed mine years ago when I removed my first set of broken studs and never put it back (bolts snapped, didn't feel like fixing properly). Anyway, my hood paint has definitely bubbled / flaked off in that area in a few spots.
Why is this any different... or better yet, why would a top mount not put more heat to the hood than stock.
Well the thinner (generally) material of the tubular top mount manifold would shed heat faster.
That coupled with the fact that whatever turbo you are running is going to have a larger, less restrictive turbine wheel and housing.
Which means less heat generated.
I have definitely noticed this on my car, previously with the car waiting at traffic lights in the rain, steam from the water could be readily seen coming off the hood.
Now with my hybrid complete with upsized turbine wheel this no longer happens.
The trade off is how much closer to the hood and spark plug wires does the new manifold come.
And also the slightly smaller diamter pipe required to retain some low end spool would also cause a heat increase.
But as mentioned that can be countered with heat wrapping, turbo beanies & or ceramic coating.
As I said earlier to me it still does not make sense to build a new manifold unless the chosen turbo simply cannot be made to fit where the stocker once did.
Seems that people think removal of the heat shield on the top of the OE manifold causes the hood paint to have problems. I removed mine years ago when I removed my first set of broken studs and never put it back (bolts snapped, didn't feel like fixing properly). Anyway, my hood paint has definitely bubbled / flaked off in that area in a few spots.
Why is this any different... or better yet, why would a top mount not put more heat to the hood than stock.
Some people have done it and it is feasible obviously, but there's a lot to consider when it comes to how capable the owner is and/or how expensive it will be. A top mount generally will be way more expensive since you have to fabricate a custom manifold, or try and adapt another to work with our heads.
Plus there's the location to consider; our cars are already nose heavy, is it smart to put a heavy turbo up as high as possible in front of the engine? I don't know if it would make any difference in handling really, but it just doesn't make sense to me personally. Not to mention a location like that makes it hard to brace the weight of the turbo, unless you put a brace on the manifold.
I think the only real advantage for our cars in using a top-mount manifold is it would make the turbo easier to access and service.
removing the heat sheild on the stock really shouldnt hurt the paint on the hood.. if you guys remember the problem that i had with my turbo.. in glowed red that basiclly lit up the engine bay.. my hood got hot for sure but i dont have any problems with my paint..
Some people have done it and it is feasible obviously, but there's a lot to consider when it comes to how capable the owner is and/or how expensive it will be. A top mount generally will be way more expensive since you have to fabricate a custom manifold, or try and adapt another to work with our heads.
No need to fabricate anything when plenty have already done it for us. The d16's are a very close match but you have to buy from the correct source. zlyricist comes to mind as he bought a d16 manifold that is a piece of garbage IIRC? But thats what you get for $99 delivered and i think he got it more out of desire for lulz rather than thinking he'd get a dope ass lovefab manifold robotically tig welded. He knew what he was getting when he got it.
Quote:
Originally Posted by Ragnarock01
Plus there's the location to consider; our cars are already nose heavy, is it smart to put a heavy turbo up as high as possible in front of the engine?
Hmm good point! Ask Honda and Acura and DSM and all the rest who have done the same thing. Ur arguing moot points bro!
Quote:
Originally Posted by Ragnarock01
I don't know if it would make any difference in handling really, but it just doesn't make sense to me personally. Not to mention a location like that makes it hard to brace the weight of the turbo, unless you put a brace on the manifold.
Again, we're far from the only car with a turbo near the headlights. As said, you could brace it on the block- not the head. The block is cast. You'd be a fool to brace it on the head just the same as it's foolish to think that hanging a big turbo from a manifold is any better than holding it from underneath. Heat rises too and I'd be willing to wager that you'd have slightly increased performance, less lag time, and a happier drive just due to using the heat a little better routing something up that wants to go up rather than down when the heat still wants to go up. I'm sure if you tested lag time along with back pressure, temp of the scroll, boost consistancy....I'd be willing to bet that pretty much everything would be better and not just on the butt dyno.
Quote:
Originally Posted by Ragnarock01
I think the only real advantage for our cars in using a top-mount manifold is it would make the turbo easier to access and service.
performance too!
Quote:
Originally Posted by compnut21
and at the same time mine had the shield and the paint is [fizzle]ed. i don't think it matters much.
6 in one hand half dozen in the other. I've seen bad hoods with no turbo and stock placement of header with heatshield. bad ideas are bad ideas. I'd want to keep it low enough that it wouldnt change much at all. But, there is always the option of heat shields and of course using your noodle when you design it in the first place.
I'm not trying to argue moot points, just wondering since I honestly don't know. To me it just comes down to what lets you fit the turbo in the easiest without sacrificing performance or loads of money, and for most people with our cars, it doesn't make sense.
And if it's about keeping your exhaust nice and hot, then isn't a shorter path with a nice thick manifold that retains heat, better than a long, curvy and thin manifold that will shed heat faster? I seriously doubt radiated heat will have as much energy or effect on spool-up as any heat the exhaust is already carrying. And when it comes to flow, why make the exhaust go down, then up, then down again when you could make it all just go down in the first place?
To me it just comes down to what lets you fit the turbo in the easiest without sacrificing performance or loads of money, and for most people with our cars, it doesn't make sense.
It doesn't? It makes perfect sense man, it just hasnt been done.
Quote:
Originally Posted by Ragnarock01
And if it's about keeping your exhaust nice and hot, then isn't a shorter path with a nice thick manifold that retains heat, better than a long, curvy and thin manifold that will shed heat faster?
depends. The stock manifold is designed pretty well- except for when you start to go above and beyond the stock turbo. A turbocharger is the first thing the airflow from your head finds when it comes out of the cylinders- this is a natural creator of backpressure and you want to avoid that as much as possible. I havent done any testing on the F2 manifold but I have with other manifolds and getting rid of uneccessary backpressure is a positive thing no matter how you look at it. If you have longer piping you allow more volume to leave that much easier from the head and its as simple as that.
Quote:
Originally Posted by Ragnarock01
I seriously doubt radiated heat will have as much energy or effect on spool-up as any heat the exhaust is already carrying.
Give that same idea to someone who has a log manifold and dynos 50-75 hp more with nothing changed except a manifold thats designed justa LITTLE BETTER. Piping length can have somewhat of an effect on spool but not as much as you'd think, unless you do it completely wrong.
Quote:
Originally Posted by Ragnarock01
And when it comes to flow, why make the exhaust go down, then up, then down again when you could make it all just go down in the first place?
The head design is lacking as it is. Most if not all properly designed aftermarket manifolds will show less backpressure than the stock cast iron piece. I've seen this many times myself. You can make a tester very easily too.
I know that having longer exhaust headers can net more horsepower, since the pulses line up and have more space to sort them selves out and prevent gasses from another exhaust port from pushing into it's neighbor, but I haven't been able to find any good arguments about having the turbo on top or on bottom.
I can see what you mean about the heat though now that I think about it more. At least if the pipes curve down first, that rising, radiated heat stays around the turbo rather than floating above it with a bottom-mount.
I would love to see some definitive numbers on this; a comparison between a top and bottom mount manifold with equal-length runners would be the best, but I can't find any tests like that (so far).
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PARTING A LOT OF 2g STUFF
