G3Karl

iTrader: (1)

How do I bypass the coolant going through the upper plenum?

goon9

iTrader: (13)

ON a vg or ve?

Greeny

iTrader: (43)

VG goon.

CapedCadaver

iTrader: (8)

look back by where the bleeder bolt is near where the fuel lines go into the rail.. you'll see 2 coolant lines near to that bleeder and just join them together.

LvR

Pic?

maxitech

iTrader: (7)

You should also do it on the front. If no one has gotten around to it by the time it warms up I'll take pics of mine when I reinstall it. I consider it a seasonal mod in the cold climates.

LvR

again

By doing it in the front you refer to the TB bypass? (ie leaving the IACV operational)

Wiking

Whole operation is waste of time, but gives all horses sun service - if hood opened outside

http://www.cardomain.com/ride/748507/8

LvR

That diagram of Wiking's explains exactly why I am so confused - IMO the best you can do for the upper plenum is to bypass the TB heater section (leaving the IACV still connected) .................. the plenum has a lot of heat being transfered to it because of the fact that its connected to the head (major source of heat) by a honking slab of aluminum guaranteeing energy transfer to it.

Wiking

At WOT the airspeed is maybe 300mph. How much would it affect oxygen content = air mass (airtemp inside cylinder) ... even if TB was red hot? One degree?

At idle the effect can be measurable. Who keeps on idling?

LvR

Wiking - I am all with you ito gut feeling wrt airspeed and the amount of heat one can transfer to the airstream using an heated intake manifold.

However - ito empirical evidence on my particular vehicle and with my particular driving style:

First - realize that our VGs here in South Africa run with no O2 sensor - ie - mixture is map controlled. (don't ask me why - I am simply stating fact).

I have had a situation on this vehicle of mine that any timing setting above about 3 degrees BTDC, I have a very faint audible ping in summer (25C+) when the motor is under heavy load AND WHILE THE MOTOR IS HOT - NEVER WHEN ITS COLD

Now I would bet that just about everybody with some internal combustion engine knowledge will immediately comment "method of setting timing is wrong" or "carbon buildup" or "too lean" or "wrong/too hot a spark-plug is used" or "thermostat wrong" or "you cannot count" or "you cannot see or are dyslexic" or "funky fuel" or ................ yada yada yada

I have investigated all of those mentioned concerns and have been completely unable to point a finger at any logical cause yet despite all changes I tried this motor is stubbornly refusing to be feint ping-less when hot.

Now in the quest to get to a point of identifying what exactly influences the onset of this "slight/feint audible ping" (have to have the window open to actually hear it) I have fitted an in-car temp meter with a easily relocatable probe in the engine bay and have logged and identified the apparent only variable responsible for this "slight/feint audible ping" ............................ the intake manifold temp.

I have over the duration of 3 summers now determined that as soon as the temp of the intake manifold throat is higher than 58C, I can expect to hear the "slight/feint audible ping" when I step on the throttle and the engine is obviously laboring (eg turning a corner at 2000 rpm in 2nd or 3rd) ................. anything below that I get absolutely no audible ping.

Now I have bypassed the TB heating and that action alone delays the intake throat reaching 58C by about 25 minutes when starting from cold and doing normal in-town driving at 20C ambient. With the TB heating connected the throat used to reach 58C in around 15 minutes with an ambient of 20C under the same driving conditions and style.

I am actually driving currently with timing at 17BTDC, getting around 10.5km per liter (auto box) on the open road and around 8.2 km per liter in town
- imo quite respectable for the size/weight of the vehicle and its performance - also quite respectable when compared to other economy figures reported ion this board - that is all telling me there really is not much actually "WRONG' with the state of tune of the motor.

I have found that if I drive around in town with TB heating bypassed, the intake manifold throat temp goes as high as 68C (without bypass it quickly sits at around 84C). If I then get on the highway, and drive about 2 km+ at normal speed (100kph+) , the inlet manifold throat temp quickly drops to 52C (TB bypassed - or 70C with normal TB heating present) and then stays there (airflow through the manifold and surrounding airflow of the engine bay reaching equilibrium).

Understand that I am not saying that I am experiencing a huge power gain (or in fact any at all) because of intake charge cooling with a "colder" intake manifold while the TB is bypassed, but I am definitely seeing some "positive" effect because of the intake being cooler on the occurrence of my "slight/feint audible ping" thing on this particular motor - an effect I have not yet been able to fully understand or explain.




ITO the thread topic, the implication is that I am convinced I can completely rid myself of this "feint/slight audible ping" thing if I can cool the intake further and keep it always below 58C on this particular motor


All of that is just for giggles and to show that my gut feel (and yours too I would say) falls quite flat when empirical evidence is actually present.

Wiking

As said, I found no WOT difference (pwr, fuel consumption) when heater hose was pinched close. You at least have manifold temp readings, I had just feelings

I'd like to get air temp tables, measured in various conditions inside the upper intake - with a sensor isolated from the aluminum block. Drill a hole, stick temp sensor in?

I dont know about ping, not heard in my max; ign set to 17°, FSM setup is 15° ±2°, 95octane. At low rpm there can be issues you describe.

I guess the whole intake heating system is stupid-unnecessary dino from carb era, 12mths a year - is it??? I mean have you ever experienced any freezing like - in a carburettor throat, +2C /humid weather?

shoult

iTrader: (1)

They heat the TB and manifold to get the engine quickly up to operating temp for emission reasons. That's really the only reason it's there.

G3Karl

iTrader: (1)

Thanks for the info. I am looking at getting a cold air intake (modified honda accord model) and if I purchase it, I want to bypass the coolant lines going to the plenum and throttle body.

LvR

Well - IMO on the VG you can only bypass the TB heating - there is nothing you can do ito coolant circulation for the plenum .................... apart from draining all the water from the radiator - See the FSM VG coolant diagram attached



Wiking - I would really love to measure those temps for various operating conditions too, but I am not going to be drilling holes in any manifold of mine just for the heck of it. In addition, my problem in South Africa is that there are very few people even able/interested enough to make such an experiment worthwhile - and anyway whatever we will measure here for our vehicles will not be directly applicable to you guys with EGR and O2 sensors present on the ECU control system. I would think that on a carb fed system that could be a real concern - I have never seen ICE as such, but I am aware of a few Golf's with Pierburg carbs going completely bonkers when ice cold and with no heating to the carb base - it would seem the vacuum advance and retard ports in the throats get completely screwed by suspected ice formation in the small holes. On the Max with an injection system there simply is no liquid (partial/fully evaporated/mixed fuel as with a carb) present to help this ice formation on the butterflies along - so yes I think its a waste on a non-throttle-body injection based engine.

CapedCadaver

iTrader: (8)

all i got to say is don't bypass the iacv. it'll screw with your air-cut valve. uim and tb are fair game tho. mine are bypassed. my heat failed last week but that's not related to my bypasses, which have been in place since last july.

Wiking

All - Audi, Nissan Bluebird etc carbs will freeze solid (work only full throttle with 2nd throttle open, 1st frozen) without heated air input in certain conditions, if no add on alcohol in gas.

Air Cut valve heating can be bypassed: The input air tube to IACV can be choked to keep airflow always below 2000rpm (=no IACV-open failure danger).

So far I have not seen reasons why this system was created; emission just isnt that one. Also cannot see any benefits taking heating out...

Greeny

iTrader: (43)

X amount of degrees cooler air introduced into the combustion chamber= less detonation possibility

Wiking

If x is unmeasurable small - then one has to rely on x-feelings or the reasonable x-theory. Nothin wrong there...

Greeny

iTrader: (43)

Or this...

http://www.globaltestsupply.com/test...ture_Gauge.cfm

CapedCadaver

iTrader: (8)

well, reduction of air temp DOES work in terms of power, as Aaron's VE picked up 8hp/10tq after he installed his spacers. And my car, tho not dyno tested, can run some pretty low rpm with no trouble, possibly due to cooler incoming air. Maybe it's placebo but for whatever reason my VG-at-the-time auto did 16.3 in the quarter with just those spacers/coolant bypass and a HAI. That's about a half-second faster than it should be. Of course my car can probably do 15s now with the 5spd but that's a different story.

LvR

I have such an infrared temp meter but its quite useless when one needs to actually see the effect on the ingested air temperature going into the cylinder - I think Wiking is right and that what is needed is a thermocouple suspended just above the injector outlet stream in each of the tubes if you want measurements to be meaningful.





My gut tells me though that any heat added to the ingested air is a bad idea - in my case it eventually leads to a slight audible ping - so removing any possible heat from that must be a good idea - if it costs you nothing then its a very good idea and if you can measure or quantify such gains to be had from the exercise as Aaron did on a dyno then its wonderful. With an autobox in mine that is close to 300K km, I am not going to toy with a dyno though as I am not chasing outright performance - based on measurements, I just seemingly need the inlet charge temps to be as low as possible to get rid of an audible irritation.

CapedCadaver

iTrader: (8)

did you get a spacer kit for your engine? if not you may consider it, though not necessary. But it lowered my whole IM, TB, and IACV by an average of 20-25 degrees F (which is... 11-14 degrees c) measured after a 1-hour idle (both before and after spacers were installed). And idling is where the engine makes the most heat since the only time air moves through the radiator is when the fans come on.

LvR

Thought about it yes, but never did it - remember I live in this armpit of the earth called South Africa where everything you guys consider to be financially worthwhile in US, costs just about double+ here ................

If you can remember, I would be interested to know actual IM temps before and after IM coolant circulation removal and finally spacer fitment - eg specifically what is your current IM temp when driving around in town?

CapedCadaver

iTrader: (8)

all the work was done at once and the only measurements taken were at idle. some parts got as hot as 165 and went down to 140, others started at 140 and dropped to 120.

as for affordability, is the economy over there so different that $120 USD is a whole lot? For example how much is a new Maxima over there, or a gallon of gas? Last check it was $3.25USD for a gallon of gas in my city.

LvR

We currently run around 1USD to ZAR7.6

So the USD120 would be ZAR912 ................. before shipping.

When I last checked, I could eventually land it here for around ZAR1600.


Gallon of gas? - 4.5 litres at ZAR8.9 = USD 5.3 (4.5x8.9/7.6)



Price of a new Maxima here? - unknown as its not marketed locally, but for comparative sake a 350Z manual goes for ZAR420000 ie USD55300 here.

CapedCadaver

iTrader: (8)

yeah everything is a wee bit more expensive over there. about 40% more. but then again, the minimum wage here is $6.15 USD/hr, and a fairly average household income is $50,000USD

sonicii

You should be speaking US gallons, which is a little under 3.8L You also need to keep this in mind when our US friends speak of MPG...

LvR

Getting very OT now but see this for a typical minimum wage situation of around 50% of the country imo with the typical income around ZAR60000 or about USD9000 PA ................. but then again I am not sure we are comparing apples with apples. Personally I am financially much better of than that, but still simply cannot afford a new car - even something like a GOLF/POLO

On the gallons vs liters thing - ok at 3.8 l/gallon I get to 4.45USD per gallon here for fuel - my apologies

Wiking

It is in the infinite long shopping list. I was thinking sticking a thermocouple into upper intake - via vacuum hose inlet. First making a wire attachment hole in the hose and then plucking the 'leak'... Cheap tst.

Two ends in the airtemp -sausage:
- cold air better as oxygen content per cubic measure is greater
- hot air is better as fuel vaporizes and mixes better (=fuel droplet size smaller)

Gasoline Drop let:
When droplet size increases, non burned fuel increases. During detonation phase, oxygen is depleted around big droplets and the droplet core never burns... pumped to exhaust From any angle that is bad. (Icy weather, nearing -40 degrees, the old carburettor saab could burn 160Liters/100miles for the first frozen mile. uh? 3miles per gallon.)

LvR

That is imo generally only going to seriously affect carb-fed motors ( throttle-body-injector fed motors could perhaps suffer a very small influence too) because the quality of the mixture is totally reliant on the mixing of the air and fuel BEFORE it actually reaches the inlet valve/combustion chamber.

With direct injection or injection right at the inlet valve, the design parameters of the injector will hopefully ensure that atomization of the fuel is accomplished as a result of the perfect spray pattern/characteristics.

On our VGs, I don't really think that a lot of improved "mixing" happens as a result of a warmer intake charge due to the extremely short distance that such mixing can actually happen in between the injector pintle and the inlet valve on the head - there just is not enough time for the fuel to collect the heat in the charge and to "evaporate" in order to increase "vaporization"

Wiking

In 'both ends of the sausage' the time window is very limited. The nozzle spray partially hits the heated lower intake body which does have effect on the spray, droplet atomization.

Evaporation (=spray)as a process is also veeery cold 'business', any help in that position must be generally positive; otherwise I cant see reason for the costly lower intake heating structure. (The direct injection tech is possibly nearing perfection when too lean mixture gets one spray and is ignited.)

I think soot in engine, nozzle tip and its condition, spray pressure, is much more important than the air 'fifty degrees' variation. Still cant say your experience woulndnt be true - there are just a lot of variables not yet discussed.

LvR

Yet its always interesting to throw ideas around - isn't it?

Wiking

I guess zillion engineering hours are/havebeen projected at that 'small' physics question of droplet atomization. That doesnt say that all ideas have already been used -or- that commercial applications could be enhanced to be better.

Driving few miles 5000rpm before emission test ensures better results. One of the many reason may be injector exercise... eg. getting possible nozzle contamination blown out, getting the gunk out from 'braking' solenoid needles. Neither well heated upper intake cant be too bad for smashin droplets...

Diesel nozzles exhibit soot collection quite fast - in city low rpm drive. After 50miles on highway, the soot 'melts' away and spray form becomes even. The situation isnt the same, but checking pictures of VGE intakes, one comes to the conclusion that oil fumes should be ventilated somewhere else than into intakes... Does this have any effect on VGE nozzle tips and spray formation?