Club G40 Forum
Technical => Superchargers / G-Lader => Topic started by: Justin14100 on January 12, 2010, 02:13:33 pm
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Just looking at a bmw intercooler from a 318, just wondering if the G lader needs a bigger front mount, cause they dont make much heat so would it make any noticable difference?
Thanks!
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I checked this out when I had the R1 charger done, with chip and 65mm pulley, these and air filter were only mods with boost recirc plumbed correctly. I put thermocouples in the charger outlet, and engine inlet before the throttle body. With normal driving the engine inlet temp was not much higher than the ambient air, charger not working too hard and outlet temps were around 60°C. When driving hard charger outlet temp wasn't getting much higher than 100°C with engine inlet temp around 30-35°C. It shows how efficient the std charge air cooler is, and is why I decided not to change it (in my opinion the boost recirc mod and fitment of a catch tank will have little effect on charger outlet temps - just opinion I have no evidence to prove either way).
The company I work for manufactures automotive heat exchangers for OEM's. We have test facilities for these, including a performance wind tunnel, one of the boys tested mine (back in '02 I think) and said it was very, very good for it's size. I have the data for this if anyone wants it.
Obviously turbo engines are a different kettle of fish.
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I think the stock IC is probably ok with the 40mm G-Lader yeah. Cetainly not really up to th job with a bigger charger, eaton or turbo though. Well, depends how much power you plan on running.
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Just found a cheap front mount thats all, not planning on chasing power but on an R1 with toothies would it make a noticeable difference? would it pull harder ect? cause my intercooler when driving around off boost gets cold, but driving hard it gets pretty warm, just keep wondering with a bigger intercooler how much colder it would be, and if that would make it much / any better?
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might make a small difference to power on a dyno with a suitable remap (cooler intake temps allow ignition advance) but it's prob not going to be very noticable on road
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So better off getting a 51mm throttle body and cleaning my intercooler up good n' proper?
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and/or saving money towards a remap. remaps are great
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even on just a 65mm and an R1 small bits like that ect?
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The other thing with a larger front mount is that it may have a worse pressure drop through it (therefore less boost), but this depends on a lot of factors in addition to charge air temp. Main ones are: -
- fin pitch (how many fins per unit length, generally more fins = better perfomance but is gets to a point where the restriction to the air flow is too great and performance will drop off)
- tube size (bigger tubes have better charge pressure drop but are less thermally efficient)
- turbulator design (basically airways inside the tubes, can either be the profile of an extruded tube or extruded plates stuffed into the tubes). Used to increase the surface area for heat exchange. But like the fins, there is always a compromise.
The std CAC will probably be OK with the boost levels of G lader, higher boost levels can cope with the pressure drop for gains in performance. High boost turbos will benefit quite a bit from a front mount.
If you do decide to change, get the newest one you can. Although the basic design of heat exchangers hasn't really changed for years, newer ones will more than likely have more efficient materials and years of minor improvements. Also beware of cheap aftermarket alloy intercoolers, they may look good but some don't have proper airways (no slits in the fins). Check also the fins are properly brazed to the tubes, poor or non existant bonding will result in shite performance.
Sorry if I've been too wordy but this is actually a subject I know something about!
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nah its good to hear someone who knows stuff!
as you cant really get colder than ambient and you said casual driving almost took it to it then it should be fine then tbh!
was looking at a 1996 bmw one on ebay, 2nd hand though. only £35!
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I'm still contemplating fitting one when I get the car back together mind. At work we make a couple of different ones for Renault/Dacia Logan, I need to compare the performance data first though to see which one, if any, will be suitable (tanks could be used but custom ally ones welded on will be best). I won't bother if they're only a little better. And unfortunaltely I won't be able to provide any as for anyone as we're only allowed to buy 2 or 3 new units per year.
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Also meant to say that if your's isn't at it's best try straightening out the edges of the fins using tweezers. Boring and time consuming, and will make your eyes go funny, but it will help restore airflow though the core and you'll get back a little bit of performance. You'll never straighten all the damaged fins though.
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it'd be a good idea to put your cooler in a parts washer or blast it out with solvent to get rid of the 15+ years worth of gunge that'll be in it.
Very good advice from Puncharado there, do you fancy writing some FAQs on IC and rad tech as you obviously know your stuff.
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Good thread.
Sorry if I'm being simple, thermodynamics has always been by engineering achillies heel, but I'm not sure I understand why having a larger intercooler (more volume in boost sysem) would result in lower peak boost?
I can see why it would take longer to build up to full boost as there is a larger volume to fill and this factor would be governed by fin pitch, tube size etc. but once the system is up to pressure assuming no leaks I don't understand why boost pressure is not just a function of charger flow rate and inlet restrictions?
Is it basically the additional 'turbulence' (non laminar flow?) generated by the longer boost system? If this made an appreciable difference from such a small change in volume though what would this mean for transcontinental gas pipelines where gas is moving at pressure across thousands of miles?
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Good thread.
Sorry if I'm being simple, thermodynamics has always been by engineering achillies heel, but I'm not sure I understand why having a larger intercooler (more volume in boost sysem) would result in lower peak boost?
I can see why it would take longer to build up to full boost as there is a larger volume to fill and this factor would be governed by fin pitch, tube size etc. but once the system is up to pressure assuming no leaks I don't understand why boost pressure is not just a function of charger flow rate and inlet restrictions?
Is it basically the additional 'turbulence' (non laminar flow?) generated by the longer boost system? If this made an appreciable difference from such a small change in volume though what would this mean for transcontinental gas pipelines where gas is moving at pressure across thousands of miles?
Remember, there will always be the same air, but with more space to fill it would lower boost, but still the same amount of air though, its why GT inlets lower the boost pressure, cause there is more space to fill
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I donno if this helps but if you think of tyres, think of a mini moto tyre? and a full size bmw M3 tyre ( 255/35/19 ) or similar running both at 32P.S.I .
the mini moto tyre takes 3 seconds to fill to 32 psi simply because theres less space even tho its at the same pressure. where as bigger tyre almost ten times longer.
the g lader only supplies same amount of air to the engine all the time but when to extend it and make larger capacities it doesn't quite make same pressure.
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Good thread.
Sorry if I'm being simple, thermodynamics has always been by engineering achillies heel, but I'm not sure I understand why having a larger intercooler (more volume in boost sysem) would result in lower peak boost?
I can see why it would take longer to build up to full boost as there is a larger volume to fill and this factor would be governed by fin pitch, tube size etc. but once the system is up to pressure assuming no leaks I don't understand why boost pressure is not just a function of charger flow rate and inlet restrictions?
Is it basically the additional 'turbulence' (non laminar flow?) generated by the longer boost system? If this made an appreciable difference from such a small change in volume though what would this mean for transcontinental gas pipelines where gas is moving at pressure across thousands of miles?
Remember, there will always be the same air, but with more space to fill it would lower boost, but still the same amount of air though, its why GT inlets lower the boost pressure, cause there is more space to fill
Right, I've written a reply for this, but I had to think a lot and I'm not 100% sure everything I have written is correct as I've never studied thermodynamics. My work background has been to do with the evaluation and testing of heat exchangers, mainly environmental and durability, but also some performance testing. I’ve picked up what I know more from practical experience, and from discussing test results with the clever guys at work who really do know this stuff. There is one bloke in particular who has been responsible for CAC development, I will ask him to look over what I've written to make sure it's correct before I post.
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Not questioning that it would take longer to build up (car tyres) or that inlet restrictions will determine peak boost pressure (inlet fannymold) what I'm struggling to understand is why effectively increasing the length of the boost system by adding a larger IC would alter peak boost with all other things being equal.
Puncharado: cheers for taking the time, I look forward to your reply. Might have to bust out the old thermo text book in the meantime though, although it'll probably make as much sense as last time! lol
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Boost is not a scientific thing. Flowing a head will drop your boost gauge reading but will actually increase power.
You can talk about mass and/or Pressure.
PV=mRT
Pressure x Volume = mass (of air) x 287 (Gas Constant) x Temp
If a bigger IC was fitted then the pressure inside your intake system will fall.
However Temp will also fall.
As a result it will take longer for your system to 'fill up' but when it does it will be colder. Massive intercoolers contribute to 'turbo lag'. One method is to have a smaller exit than intake on the IC.
On the subject - Check out Yoof's boost pipes. Unless hes fiddled recently then he has the old PSD ones which are much better than most.
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Varley - To answer more directly.
boost is not real. Your boost gauge measures manifold pressure (which is why you have a negative reading sometimes).
And things don't stay they same. They cant. That in itself is thermodynaics.
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OK, spoke to a couple of guys at work and I've got a couple of things wrong with the original post that was here, now I've discussed it some seem obvous, others not so. So I've deleted it and will re-write it later, but this time I will get it double checked before I submit as a new post tomorrow.
Sorry to mislead you guys.
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Banging Thread, the fact that I am studying thermodynamics and seeing it discussed in this context is great :)
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Banging Thread, the fact that I am studying thermodynamics and seeing it discussed in this context is great :)
Bless. You still have not found Flowmaster yet ;D
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Just a wind tunnel mate ;)
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Spill the beans. Where are you?
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Leave my boost pipes out of this :P
Unless you're thinking of fitting an intercooler bigger than the surface area of the front end, the 'lag time' change will be insignificant.
For arguments sake the air required to make 170bhp is (very) roughly 500kg/h i.e an utter sh1tload! So the actual mass of air your charger is pumping out would take fractions of a second to fill most intercoolers, when you consider the volume differance between the two, and the mass of air being flowed, the 'lag' time becomes somewhat irrespective.
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This is a good thread and just have a question.
If you leave a standard IC on but want cooler air would getting a aquamist kit help? I know its alot more expensive but dont aquamist kits lower temp as well?
Could always get them other types of intercoolers that arent front mount, charge cooler?
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They are all charge air coolers (this is the term most often used by OEM heat exchange manufacturers and the car makers when refering to intercoolers), whether air/air or air/water. In theory water cooled CACs should be more efficient because the thermal coefficient of each fluid is vastly different (don't ask me figures!), so it's easier for water to take heat from the charge air. Air/air coolers are less efficient because even though there is a temp difference between the charge air and cooling air the thermal coefficient is the same. But all this ultimately depends on the design of the core, whether air or water cooled. Water/air CACs are not often used in mass market cars due to cost, packaging, the need for additional plumbing and the cooling water will often need it's own rad. Both normal engine coolant (with auxilliary rad) or stand alone (with seperate rad) supplies can be used.
Water spray kits will certainly help get your charge air colder, it increases the heat exchange in the same as why a wet hand feels colder than a dry hand or why your body sweats to keep you cool, the heat is more effectively removed from the surface.
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Thanks for that, that makes sense. I remember yoof selling a water charge cooler that had its own rad that went cheap but never got the chance to get in contact cause i would love one, but i am gettting an aquamist kit so i might not worry.
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Spill the beans. Where are you?
Sheffield University pal
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What is the AMRC like? Looking to do a masters in composite engineering you see.... ;D
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http://www.amrc.co.uk/
this is wot you mean right
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Going back to the question of why will a bigger intercooler mean less boost, im crap at thermofluid science but I might be able to add somthing.
Any system carrying a fluid will suffer a 'head loss'. This is due to the energy required to move the fluid being taken from its pressure. Flow rate must stay the same. So there will be a bressure differentia between the inlet and outlet of the IC. BUT, it will flow the same amount of air in as it does out, so I might be right in thinging that it will just create more pressure between the Glader and the IC, because the IC is acting as a sort of 'resistor'.
All a bit stabbing in the dark, I should have payed much more attention.