I Want My Skyline To Rev

[rev210]

Just to add some more info to the stock intercooler theory debate:

To be fair my old Gtst had the ducting and free flow out the back of the factory unit, unlike probably everyone elses. I feel I could help replicate the results or perhaps better, if anyone wanted to have a go.

This may show what ducting can do for an intercooler?

*Torque isn't an issue, could you make more with a FMIC? don't know really, perhaps with a better intercooler core 'period' it should?

- My old Gtst made 170rwkw at only 4800rpm 10-11psi. Limit of 4800 was due to an injector issue at 5,000rpm and above.

- This run was done with the bonnet 'down'

- The power figure was on the last run as we were fault finding, so heat soak didn't really hurt anything even though it was a hot day.

I also had my turbo outlet pipe 'to intercooler' thermal wrapped along with the dump pipe. I also improved the factory turbo heat shields, added extra bits to them and futher insulated the internal part of them with thermal tape. Not that it does a hell of alot but, every little bit counts. Looking under the bonnet of my cars has never been much of a show.

It would be nice to see a little more info on the R34 and how far it can go, we have an example or two from Sydneykid at the 220-230rwkw point but, a flow bench test (with all the pipes from turbo to throttle body) back to back with a popular FMIC kit would be interesting too.

Edited November 23, 2006 by rev210

[J_Red33]

Yes it does sound like your set up was well optimised, unlike my own with no ducting.

Torque in itself isn't an issue, it's maintaining it. Torque is relative to power so the less torque you have for a given rpm the less power it will equate to (same torque at higher rpm = more power). I will have to scan & post up my dynograph to show you what I mean. Basically right front the get go at around 2500 rpm till about 500 to 600rpm later (my graph only shows wheel speed I'll have to actually calculate it out) it stays fairly flat. After this though is starts to progressively drop off throughout the rev range, except when the boost level increases, after which it just drops off even faster.

I have been running the stock controller again as after I stuck a newer design replacement dump on (the old 1 cracked), the boost just went sky high with the ball & spring POS I had installed & hit boost cut. I couldn't turn it down enough.

My peak power is somewhat later than your own was at roughly 6000 to 6200 rpm since everything is running fine, but the power curve at this point is looking rather flat due to the torque drop off. It doesn't look a lot different to what a stock 33's dyno graph does, just with much higher figures, though a little flakey at the top end.

I would have thought it would be a bad idea to insulate the pipes after the turbo, as the air that comes out of the turbo will probably be hotter than the air in the engine bay. After the intercooler may be very useful though to stop cooled air heating back up, as well as wrapping the exhaust as you said.

I have no doubt the R34 SMIC flows & cools better than an R33's, but against a deacent FMIC I reckon it would still be way lower. From what I've read before 220 -230KW is about it's power limit. Still it would be good to see some actual bench flow figures as well as measurements of temperature changes of all 3.

Edited November 24, 2006 by JazzaR33

[rev210]

wrapping the 'hot' side is because it tends as you say to be hotter than the engine bay. With that in mind I try to keep it's extra heat sealed in and let the intercooler take care of the business of getting the heat out. If you can reduce the engine bay temps as a whole it lowers the heat soak that everything cops. So things like the plenum etc are a little cooler. Not to mention reducing the number and severity of burns you get working in a hot engine bay

No harm wrapping the 'cold pipe' all the same.

Edited November 24, 2006 by rev210

[mokompri]

I would have thought it would be a bad idea to insulate the pipes after the turbo, as the air that comes out of the turbo will probably be hotter than the air in the engine bay. After the intercooler may be very useful though to stop cooled air heating back up, as well as wrapping the exhaust as you said.

im in the opinion that wrapping the cold side is a fruitless idea, the speed at which air travels through there means it wont aborb enough heat for any measurable temperature change. there was a thread where SK had some experience with this and had some numbers to back it up.

im also in the opinion that wrapping anything after the turbine, dump pipe onwards, does nothing for power, unless its to stop heat soak under the bonnet - it doesnt help with exhaust flow, if anything its a step backwards imo

[J_Red33]

Under sustained full throttle there's no way that wrapping the cold side has any measureable affect, however under light loading it may be another story, but it's all a matter of how insulating the pipes themeselves are in the first place.

If the pipe material has poor thermal conductivity or is fairly thick it probably wouldn't do a lot, in constant heavy driving. However with thick piping, they may warm up a bit if driven only lightly for a sustained period & may possibly take several seconds to cool back down. Thin piping would actually cool a lot quicker with the intake air rushing though.

I'm not sure how SK did his testing (haven't seen the thread) but for track work I'd agree that it would be useless. This may actually be more useful on the road.

I wouldn't expect any power gain with the exhaust wrap either, but it would help with the engine temps. But then again why do they do ceramic coating of exhausts? Even manufacturers have done this so maybe there's something to it.

[rev210]

The factory cast alloy intake/ cold pipes are pretty thick and do stay hot for a while since there is enough mass to hold onto a bit of heat, so there's probably a little to get by wrapping them, no harm since they look pretty ugly. Less of an issue if all the pipes are thin though.

Just on the cooling side it's also worth throwing some slightly longer bolts with some washers onto the bonnet hinge to give you a little gap at the back to aid the air getting out.Bit of an old school mod that one but, one that works very well. The good thing about my old R32 GTR was Nissan must have thought that one ahead, they have a rubber seal that you can remove covering the gap the bonnet position already has, you just take it off and hey presto! . I noticed an intake temp drop of 2 degrees on the R32 GTR ,which is pretty good.

Most of the other cars I did it to being much older grabbed some even bigger gains (7-8 degrees).

[toffy]

R33 manual diff ratio is also 4.111 & more than short enough. If you make the engine more responsive from the bottom end, you will definantely not want shorter gearing than a 33 already has. 1st gear is only good for 60 & second for 100 & cruising at 100 in fifth still has it reving at over 3 grand. I've always thought if I can't find a six speed to suit my 33 I'll be trying for a taller diff as first is just so short that the stock engine can't spin up fast enough & it revs too high when cruising. If you shortened the gearing that would only make it worse, not to mention fuel economy also goind down the drain.

You would also loose time in having to do more shifts to get to the same speed, not worth it IMO.

Do all the other engine mods & it'll pull like a train in any gear anyway.

my r33 has a 3.79:1 diff ratio and its a factory manual , and yes ive seen it with my own eyes

[mokompri]

Under sustained full throttle there's no way that wrapping the cold side has any measureable affect, however under light loading it may be another story, but it's all a matter of how insulating the pipes themeselves are in the first place.

If the pipe material has poor thermal conductivity or is fairly thick it probably wouldn't do a lot, in constant heavy driving. However with thick piping, they may warm up a bit if driven only lightly for a sustained period & may possibly take several seconds to cool back down. Thin piping would actually cool a lot quicker with the intake air rushing though.

I'm not sure how SK did his testing (haven't seen the thread) but for track work I'd agree that it would be useless. This may actually be more useful on the road.

I wouldn't expect any power gain with the exhaust wrap either, but it would help with the engine temps. But then again why do they do ceramic coating of exhausts? Even manufacturers have done this so maybe there's something to it.

that may be true about light load, but at the same time under light load and no boost the temps out of the compressor will be ALOT lower to begin with. so you have to wonder again if there is anything to be gained.

ceramic coating of say the turbine housing and exh. manifold will be beneficial because you want to retain energy, not expel it - which is what you want to do once you get to the dump pipe. the reason why manufacturers do it, is either to stop rust or keep engine bay temps down - with the latter being important to stop ancillaries melting in the engine bay, its not a performance thing.

rev210 once mentioned i should look at motorsport and note that its used (heat wrapping, ceramic coating), and therefore must be beneficial to performance.. i look at the pinnacle of motorsport - F1, and i dont see it.

[rev210]

mokompri,

How hard did you look at F1 or Indy Car?

It's probably pretty hard to get info on it to be fair as it's such a small bit of tech on such a big operation like F1.

Zircotech was one name involved in developing a range of technologies on contract for various race teams around the world, they are largely an organisation that develops technology for licencing. The ceramic coating has been used in the formula 1 space.

They outline the reasons in basic form here;

http://www.zircotec.com/exhaust.html

It's a very interesting website in general.

HPC , a fairly popular brand name ceramic coating place has had involvement in a couple of the Indy Car and other teams over the years, in the exhaust coating products area.

The physics I think I alluded to in our previous discussion are based around the emissivity and how the trapped energy effects the gas/air density and hence increases it's flow.

Emissivityis the ratio of reflected Vs absorbed engery at the same temperature. A true black body has a ratio of 1 so for applications trying to keep the energy within the diameter of the object a lower ratio is the goal. By having trapped a greater amount of energy inside the object the thermal efficiency is greatly increased and therefore air/gas density is kept lower and gas flow veloctiy is higher.

Strangely this is a good part of the reason why the 'hemi' chamber head works better than a conventional style ,it has greater termal efficiency in it's abillity to keep thermal energy in the chamber to lower exhaust gas density further and thereby get it out the exhaust valve quicker. You can get a conventional head to flow just as well on the bench in terms of numbers but everyone one knows once it goes into action the Hemi head based motor is going to make more power with everything else being equal. You can make this even better from a performance point of veiw by ceramic coating bits in the combustion chamber to trap more heat in. Tops of pistons combustion chamber and valves etc. Quite a bit of data on the power increases in that space too.

Just thought that might add a little to the discussion from the side.

It is a very hard thing to completely understand all the same (I'm not altogether full bottle and I don't think I ever could be) but, the evidence seems to support the theory that it is a performance thing too.

[J_Red33]

Complex explanantion, but I get the picture .

I more basic terms, ceramic is a poorer conductor of heat than Iron or alloy etc & basically acts as an insulator to help prevent heat absorbtion by the engine parts that are coated with it.

Because of this the gas remains hotter as it's fed out the engine & via the turbine, creating greater flow due to the fact space that the gas requires is greater.

Keeping the engine cooler any way possible means greater efficiency so there has to be some sought of power gain there. Contradictory to what I said before I know, but this makes perfect sense after looking at it a bit more.

Edited November 27, 2006 by JazzaR33

[mokompri]

mokompri,

How hard did you look at F1 or Indy Car?

It's probably pretty hard to get info on it to be fair as it's such a small bit of tech on such a big operation like F1.

Zircotech was one name involved in developing a range of technologies on contract for various race teams around the world, they are largely an organisation that develops technology for licencing. The ceramic coating has been used in the formula 1 space.

They outline the reasons in basic form here;

http://www.zircotec.com/exhaust.html

It's a very interesting website in general.

HPC , a fairly popular brand name ceramic coating place has had involvement in a couple of the Indy Car and other teams over the years, in the exhaust coating products area.

i looked at a few pictures of F1 engines and its obvious that they have no coating at all, nothing better then visual evidence. most notably on the renault and toyota engines are pics that i found. the thing with F1 is, if its a worthwhile modification, ALL the teams will run it, so i dont see any reason some may run it and people like renault and toyota wouldnt (couldnt find any pics of new f1 engines running a coating).

nice website and ive noted a few interesting points from it. the company says they are involved in F1, but dont mention any specifics/teams, for all we know it could have been a test run in the 70's.

heres a quote on their website (press release/plug section) from someone in le'mans who ran it on a judd engine, this is what they had to say

Engine bay temperatures were reduced and we did not have a single exhaust manifold problem

thats it. note it doesnt mention any increase in power at all, simply a reliability mod.

heres another quote from someone who used their stuff:

The Zircotec coating is proven to significantly reduce engine bay heat build up, even offering better engine performance. “The more heat and energy you can keep in the system, the faster the turbo will spool up, making the car more responsive,” explains Iain Litchfield, managing director of Litchfield Imports who are using the technology on their 415bhp Impreza Type 25. “We’re finding it’s bringing the turbo up to speed 300 or 400 rpm sooner, which you can really feel in the crispness of the throttle response.” In addition, lower air intake temperatures increase charge density and can lead to power gains.

When applied to an exhaust system, the Zircotec coating inhibits the radiation of heat from the surface of the material, holding the heat inside. Testing on race cars has shown reductions in under bonnet temperatures by up to 25ºC, in one example even preventing a previous problem of melting spark plugs.

again there is no mention of an increase in power, but rather a faster spool which would be indicative that it was used on the exhaust manifold and turbine housing, areas where retaining energy is a good idea - and then again alluding to under bonnet temps.

and then another quote from their website:

Applied to the exhaust manifold using a high-temperature plasma spray, the Zircotec coating greatly reduces the release of heat, helping to protect the finish of the manifold, the engine and other components in the engine bay. The coating can also be applied to turbo housings, cam covers, heat shields and other metal components.

no mention about power increase, or exhaust flow.

then the only tech data, or anything closely related to numbers backing some performance increase is this:

relating only to under bonnet temps.

infact the only thing they mention about there exhausts having some good effect directly for exhaust flow are these 2 quotes:

greater gas velocity - more engine efficiency

reduced back pressure and increased high velocity gas flow to create a supercharging effect

some real technical stuff there ! somehow gas velocity is directly related to engine efficiency ?! and then somehow we have a 'supercharging effect' by retaining energy in spent gasses, then they falsely claim increases in gas velocity - where physics dictates they will mearly be able to maintain velocities.

all in all, it looks to me like another company just trying to push their product with vague claims and supposed relations with motorsports, and why wouldnt they ?

The physics I think I alluded to in our previous discussion are based around the emissivity and how the trapped energy effects the gas/air density and hence increases it's flow.

Emissivityis the ratio of reflected Vs absorbed engery at the same temperature. A true black body has a ratio of 1 so for applications trying to keep the energy within the diameter of the object a lower ratio is the goal. By having trapped a greater amount of energy inside the object the thermal efficiency is greatly increased and therefore air/gas density is kept lower and gas flow veloctiy is higher.

Strangely this is a good part of the reason why the 'hemi' chamber head works better than a conventional style ,it has greater termal efficiency in it's abillity to keep thermal energy in the chamber to lower exhaust gas density further and thereby get it out the exhaust valve quicker. You can get a conventional head to flow just as well on the bench in terms of numbers but everyone one knows once it goes into action the Hemi head based motor is going to make more power with everything else being equal. You can make this even better from a performance point of veiw by ceramic coating bits in the combustion chamber to trap more heat in. Tops of pistons combustion chamber and valves etc. Quite a bit of data on the power increases in that space too.

Just thought that might add a little to the discussion from the side.

actually you never alluded to black body radiation at all, and rightly so as its not really applicable here. you alluded to viscosity and incorrectly put it in the context of gasses, where it only exists in fluids. the discussion basicly came down to 2 factors, the loss of heat in the gasses meant we ended up with a denser gas which means a pipe of a certain diameter will flow more mass because its denser. the downside and other side of the coin was, that with the loss of heat the gas loses energy and velocity, which is also true.

so then it was a toss up as to which of these effects was more beneficial. and since then i put some numbers together from the common gas laws, and found that a denser gas is more favourable to a faster gas in terms of flow capacity. heres the data that show this;

the kelvin temperature is directly proportional to the kinetic energy of a gas. so that means with the temperature halved, the kinetic energy is also halved. now the speed of the gas/molecule is related to its kinetic energy or temperature, but not proportionally. kinetic energy = speed^2 or speed = kinetic energy^0.5.

not needing absolute numbers, we will use relative ones and apply 100 as the kinetic energy:

speed = kinetic energy^0.5

10 = 100^0.5

now we halve the temp/kinetic energy and we get:

~7 = 50^0.5

so by halving the temp (K) of the gas, we have gone from a speed of 10 to 7, 30% loss in speed/flow.

then we consider the density argument, these are the common gas laws:

V = kT

P = kT

V = volume

P = pressure

T = temperature

k = a constant of proportionality

what this tells you is, that halving the temperature of the gas halves the volume it takes up. which means you have doubled the pipes flow capability. which also means, it outweighs the loss of speed the gas has incurred. plug any numbers in the equations and the denser gas will always be ahead in terms of flow.

what you say about combustion chambers doesnt apply here either, its a part of the engine which benefits from energy retention as it still has use for it, much like retaining energy/heat in the exhaust manifold and turbine housing is beneficial. the exhaust is all about expulsion of energy.

EDIT: here are the sources i used for the gas laws etc

http://id.mind.net/~zona/mstm/physics/mech...emperature.html

http://www.answers.com/topic/gas-laws

Edited November 27, 2006 by mokompri

[rev210]

Hi,

The F1 exhausts are now made of inconel which if polished has a very very low emissivity .Not a great deal of need for the coating there. Although it might help. Why did they go for inconel?

here is a pic of a renault motor I found from the 2005 season 'coated'. As you say some are & some (polished inconel aren't).

I think we agree about the exhaust manifold and turbine all the same

The zicotec web page I linked mentions power increase if you look down near the bottom of it.

[Abo Bob]

Without wanting to take away from your well thought out post (which I enjoyed btw), I just wanted to suggest that while halving the temperature of the exhaust gases by not insulating (to use your example) might flow double the gas through the given exhaust manifold, or to try to be more precise, double the molecules, I don't see how this will impart more energy to your turbine as it passes through it.

Double the gas taking up the same amount of physical space but at 30% less velocity? Surely this is not helpful.

..

Unless the greater density of gas passing through the turbine somehow has more torque and therefore gets the turbine up to speed faster than the higher velocity, lower density gases, in which case the only benefit of this method is faster spooling, although there is now less restriction on the exhaust side so perhaps you would have a cleaner charge in the cylinders, particularly with big overlap cams.

But I don't think it does.

Shit, count the commas!!

I know a racer who swears by the stock extrude honed and coated exahust manifold for RB26 because it (allegedly) spools the biggish turbos faster, even if it might be a restriction compared to other possibilities at higher revs. They have proven that swapping some bottom end for top end power does not always get you a faster ET.

[mokompri]

Hi,

The F1 exhausts are now made of inconel which if polished has a very very low emissivity .Not a great deal of need for the coating there. Although it might help. Why did they go for inconel?

here is a pic of a renault motor I found from the 2005 season 'coated'. As you say some are & some (polished inconel aren't).

I think we agree about the exhaust manifold and turbine all the same

The zicotec web page I linked mentions power increase if you look down near the bottom of it.

straight from wiki:

Inconel alloys possess several properties making them well suited for service in extreme environments. Inconel is very resistant to oxidation and corrosion. When heated, inconel forms a thick, stable, passivating oxide layer, protecting it from further attack.

Inconel retains strength over a wide range of temperatures. This makes it particularly attractive in high temperature applications where aluminum and steel would "soften"

that probably explains why iconel is used. F1 being F1, they would have taken insulation to the extreme if there was any gain to be had imo. btw there is no pic in your post

Without wanting to take away from your well thought out post (which I enjoyed btw), I just wanted to suggest that while halving the temperature of the exhaust gases by not insulating (to use your example) might flow double the gas through the given exhaust manifold, or to try to be more precise, double the molecules, I don't see how this will impart more energy to your turbine as it passes through it.

Double the gas taking up the same amount of physical space but at 30% less velocity? Surely this is not helpful.

..

Unless the greater density of gas passing through the turbine somehow has more torque and therefore gets the turbine up to speed faster than the higher velocity, lower density gases, in which case the only benefit of this method is faster spooling, although there is now less restriction on the exhaust side so perhaps you would have a cleaner charge in the cylinders, particularly with big overlap cams.

But I don't think it does.

Shit, count the commas!!

I know a racer who swears by the stock extrude honed and coated exahust manifold for RB26 because it (allegedly) spools the biggish turbos faster, even if it might be a restriction compared to other possibilities at higher revs. They have proven that swapping some bottom end for top end power does not always get you a faster ET.

no no you have me all wrong, re read what i said

i said its not worthwhile retaining heat from the dump pipe onwards. certainly as i said, you want a high pressure sparse gas with as much heat as possible in the exhaust manifold and in the turbine housing, and a denser cooler gas from the dump pipe onwards. this gives the greatest pressure differential pressure across the turbine, which gives it its power.

like i said, energy retention in the exhaust manifold and turbine housing is good, because it still has work to do (spin the turbine), but once it hits the dump pipe its a matter of just expelling energy and matter as quick as possible.

[Abo Bob]

Oh right, yes I agree there. I thought we were talking about hpc coating exhaust manifolds.

[discopotato03]

Very topical points here .

1) Large front mount intercooler will always flow more air and have less restriction . Best of British . Large FMIC's are not all the same and some bloody awful . How many times have you seen the large glitsy bling IC with shallow end tanks and fittings with a short shot basically at the core tubes in line with them . Air is like most things - it has mass and the faster it moves the less it wants to change direction so many of the bling or should I say Ka Ching coolers don't effectively use much of their core area . Some auto manufacturers ie Nissan with the GTR and Porsche (sp?) go to a lot of trouble to make their tanks feed and collect from the core tubes properly and is why they work . So not every big intercooler is a good one . First a good intercooler has to have little resistance to airflow because cooling efficiency means little if it can't pass the gas .

2) Thermal issues . There will always be a tug of war between getting best use of hot expanding exhaust gasses for the turbocharger and keeping the engines structure long term reliable . Provided you can keep the heat in the gas it has a chance to maintain high velocity . Provided you can control the temperature of things like pistons valves head manifolds turbines/housings you have a say in their useful life . I believe ceramic thermal barrier coatings have the ability to shield to a degree components that feel the fire so they suffer less of the thermal lashing that kills components over time . Thermal wrapping exhaust manifolds seems to pay off probably because the gasses need to be directed to a central location and ducted into a turbine housing so a lot of heat is concentrated in this area . It probably has the greatest potential to remove heat than any other component which is why over the years so much effort is thrown at competition exhaust manifolds .

I feel that a lot can be gained from removing the restrictions in our production based engines so that they don't really need to be run in high states of tune to get impressive power . Having a lot of heat is one method , having less restrictive gas paths is another .

Cheers A .

[Roy]

hehe...you are all science geeks

[mokompri]

Having a lot of heat is one method , having less restrictive gas paths is another .

could you elaborate on that?

roy, science is for cool people :sorcerer:

[Roy]

Wrong, when studying science you are everything but cool, my blood pressure is normally through the roof