Dez
Club Retro Rides Member
And I won't sit down. And I won't shut up. And most of all I will not grow up.
Posts: 11,712
Club RR Member Number: 34
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cylinder head temp gauges.Dez
@dez
Club Retro Rides Member 34
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Oct 25, 2014 18:33:17 GMT
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prior to my bmw TDS install, ive been warned by various sources i need to keep an eye on cyl head temps on this motor, as they're known to crack heads.
ive never bothered with one in the past on any cars ive played with, i always just assumed you could get a good idea from the water temp. but, if i were to fit one, where is the 'best' place to get a true reading? i would guess at as far away from the cooling effect of the water jacket/oilways as possible, whilst been as close to the combustion chamber as i can, as this is theoretically the hottest place?
also, am i missing something or is a cyl head temp gauge basically just a water temp gauge with some different words on the face?
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sowen
Club Retro Rides Member
Posts: 2,245
Club RR Member Number: 24
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cylinder head temp gauges.sowen
@sowen
Club Retro Rides Member 24
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Oct 25, 2014 18:43:35 GMT
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I can only speak for the air-cooled piston aircraft I work on and the cht probe generally goes into the head on the side of the combustion chamber. Would an exhaust gas temp gauge be more suitable and more easily acquired?
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Dez
Club Retro Rides Member
And I won't sit down. And I won't shut up. And most of all I will not grow up.
Posts: 11,712
Club RR Member Number: 34
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cylinder head temp gauges.Dez
@dez
Club Retro Rides Member 34
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Oct 25, 2014 18:59:03 GMT
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not sure, thats why I'm asking!
from what ive seen of the head temp gauges on ebay and the like, both gauge and sender look identical to a water temp gauge, and the scale is the same range, leading me to think its the same guage with different wors printed on it and a few extra quid on the price. none of them elaborate on where/how you should fit them though.
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sowen
Club Retro Rides Member
Posts: 2,245
Club RR Member Number: 24
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cylinder head temp gauges.sowen
@sowen
Club Retro Rides Member 24
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Oct 25, 2014 19:19:35 GMT
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I know from reading up on the Mercedes diesels they recommend egt gauges to monitor the temps to help prevent the pistons melting and other overheating issues, but never come across cht outside of aviation?
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Dez
Club Retro Rides Member
And I won't sit down. And I won't shut up. And most of all I will not grow up.
Posts: 11,712
Club RR Member Number: 34
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cylinder head temp gauges.Dez
@dez
Club Retro Rides Member 34
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Oct 25, 2014 19:25:39 GMT
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i could do it with egt, i suppose. what ive come across is a few people recommending keeping an eye on head temps if I'm tuning it as TDS are known to crack heads when pushed hard, and i assumed a head temp gauge would be the best way to do this. on an intercooled turbo'ed setup, i don't see how EGT would be particularly relevant to head temp, and by the time it had risen enough to be noticable, id expect it would be too late for the head anyway
id be better off keeping an eye on air temp after the intercooler, surely? as that more directly effects head temp.
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Oct 25, 2014 20:26:16 GMT
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id be better off keeping an eye on air temp after the intercooler, surely? as that more directly effects head temp. ^^^^ This would be my feeling on this issue... The heat of the charge would be the biggest factor affecting the cylinder head temps, so, if you can keep that low and monitor it, you have a greater chance of preventing the engine from grenading itself... An added bonus is the fact that the cooler the charge, the more fuel and air you get into the engine, along with a more efficient burn and more power from said charge...
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'96 Volvo 850T5 x2, '97 Alfa 145 Cloverleaf '96 Alfa 155, '91 XR2i 2.0 Zetec (sold), '88 BMW 520i slug (sold), '81 Escort Mk3 Project, '68 Mk1 Escort Estate, Berlingo Parts Chaser.
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Dez
Club Retro Rides Member
And I won't sit down. And I won't shut up. And most of all I will not grow up.
Posts: 11,712
Club RR Member Number: 34
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cylinder head temp gauges.Dez
@dez
Club Retro Rides Member 34
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Oct 25, 2014 21:14:38 GMT
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a mate was going on about a water cooling spray system for the intercooler if necessary to keep the temps down, so ive been musing on a inspired/idiotic system based on the twin washer bottle system e30s equipped with headlamp washers had, controlled by one of those adjustable fan controllers, but fitted to the pipework after the intercooler instead of the rad hose. charge gets too hot=turns spray system on. no idea if it would work, but if it would its better to have it automated rather than having to watch the gauge constantly and press a button to make it work. until i get it up and running and a gauge installed, ive got no idea what the actual temps involved would be, but as i understand it as long as the fuel isnt icing, it cant be too cold- hence car manufacturers going to cold climates to get their performance figures for their new models, because as you say, cold air makes em more efficient.
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Last Edit: Oct 25, 2014 21:18:08 GMT by Dez
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Oct 25, 2014 21:27:36 GMT
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A water injection system would keep the temps down, if you're going to the trouble of tuning a methanol injection system would be even better.
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Oct 25, 2014 21:27:47 GMT
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that's exactly what some subarus had, so not that hairbrained of an idea.
tbh though with a front mounted intercooler heatsoak "shouldnt" be an issue as it was on a top mounted interwarmer of the subaru boxer 4, you just need a proper setup of fuel and the right turbo and control system.
I've not heard much on tuning the M51D25, the limited amount I have heard is that the pump is nigh on flat out with just a chip so it sounds like the pump needs adressing first then possibly a larger TD04 bunging on from something like a subaru or a saab aero.
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Dez
Club Retro Rides Member
And I won't sit down. And I won't shut up. And most of all I will not grow up.
Posts: 11,712
Club RR Member Number: 34
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cylinder head temp gauges.Dez
@dez
Club Retro Rides Member 34
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Oct 25, 2014 21:39:48 GMT
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I'm already way ahead on that. theres another thread on here recently about bosch VE pumps.
basically i managed to ascertain the TDS pump has a 10mm head, but its a 10E, which is cutaway a bit near the top to allow faster filling, so its a bit better than a normal 10mm one. I'm going to a fully manual pump instead of the electronically controlled TDS one, and I'm going for a 12mm head. not sure what camplate i will use yet, i need to see some side by side to see which is more agressive.
standard turbo is a TD0411G4 on earlier cars, and a TD0413G04 on later cars.(basically, it has a very small hotside, 4cc) i plan to go up to the saab TD04HL15T06 to start with, with maybe a coldside upgrade later on if necessary.
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Last Edit: Oct 25, 2014 21:41:40 GMT by Dez
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Oct 25, 2014 22:06:17 GMT
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awesome is the early vs late turbo related to when they changed from top mount to underslung?
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Dez
Club Retro Rides Member
And I won't sit down. And I won't shut up. And most of all I will not grow up.
Posts: 11,712
Club RR Member Number: 34
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cylinder head temp gauges.Dez
@dez
Club Retro Rides Member 34
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Oct 25, 2014 22:12:11 GMT
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not afaik, theres no documented reason as to why they did it, or any stated power increase either?! i *think* it changed when they went from OBD1 (non-imobilised) wiring system to OBD2 with a transponder key.
e36 fitment is low mount, e34 is top mount.
i have a OBD1 e34 setup, so the 'best' one to have for engine swaps, but the smallest turbo.
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Last Edit: Oct 25, 2014 22:15:53 GMT by Dez
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Oct 25, 2014 22:24:10 GMT
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I remember in the early and mid 1980's Saab used water injection to keep intake temps low, to some degree of success as I recall.... I remember having a 900 Turbo with water injection, and the difference in performance to a car not equipped with it was quite considerable.... Might be worth researching it for your application Dez...
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'96 Volvo 850T5 x2, '97 Alfa 145 Cloverleaf '96 Alfa 155, '91 XR2i 2.0 Zetec (sold), '88 BMW 520i slug (sold), '81 Escort Mk3 Project, '68 Mk1 Escort Estate, Berlingo Parts Chaser.
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Oct 25, 2014 22:44:39 GMT
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Ford use CHT sensors in their Transit/Mondeo TDCi engines, fitted deep into the end of the cylinder head. Can't offer much more info other than they reduce power if temp gets too high and can fail without triggering a fault code.
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Oct 25, 2014 23:59:11 GMT
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Hi, some of this is going over my head! but I have some questions? What is the critical temperature? As stated lowering incoming air temp and water injection produce more power and so more heat, doesn't this make the situation worse? If you try to bring the temp down by reducing fueling will this not cause pinging ie, a rise in temp and pressure? Reducing boost by dumping or backing off the pedal may not be convenient if you are in the middle of some thing? Whatever method is used, how quickly will temp reduce?
Sorry for all the layman type questions, I am trying to keep up even though I am at the back!!
Colin
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Fungus
Part of things
Posts: 960
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There's a few temp gauges available for bikes that use fitting that go under the plugs, that'd probably be a decent reading?
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If you try to bring the temp down by reducing fueling will this not cause pinging ie, a rise in temp and pressure? Dez is talking about a diesel engine, so no. On a diesel, the fuel mixture is constantly varied by the accelerator pedal as the main method of controlling engine power. Inject more fuel to go faster, less fuel to go slower. Their air-fuel ratios vary wildly all over the place as you drive, but essentially the more fuel you burn, the hotter they will run. Petrol engines work differently because the air intake is throttled, so you are reducing the cylinder pressure by reducing cylinder filling, rather than air/fuel ratio.
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Dez
Club Retro Rides Member
And I won't sit down. And I won't shut up. And most of all I will not grow up.
Posts: 11,712
Club RR Member Number: 34
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cylinder head temp gauges.Dez
@dez
Club Retro Rides Member 34
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Oct 26, 2014 10:26:01 GMT
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as noted, its a diesel, so slightly different to the convention of petrol engines. basically everything is controlled by how much fuel you do/don't put in, and little else. it also means a bike temp sender that fits to a plug wouldnt work, cos i aint got none of them.
colnerov, id agree it would be a bit of a vicious cycle, to an extent. head gets hot, develop a way of cooling it, so you end up pushing it harder without issue, but then gets hot again cos youre pushing harder, so you then need to develop a way to cool it further... as i can see though, excess cyl head heat is the only real limit to what power you can produce from a hot diesel(providing you can get enough fuel in), so its worth thinking ahead about ways to reduce it.
greg, i can probably find a transit or mondeo to have a look at, cheers for that info. do you know roughy where on the head the sender is?
retroandproud, not sure ive ever seen water injection on a derv, will have to look into that. ive read propane injection can actually cool the charge on diesel, but to me id think the opposite would happen? thats something else i need to look into too.
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Oct 26, 2014 10:39:16 GMT
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I used to be quite heavily involved in rallying, and in 2001 M-Sport built a diesel Focus FWD recce car which was used on the Welsh stages. It was a 1.8 Endura DE running a reliable 220bhp, and it went like a stabbed rat!!! Not sure how they achieved it, but there are a few people I can check with to find out some info if you like? Might take a while tho', I'm fairly tied up with work stuff at the moment...
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'96 Volvo 850T5 x2, '97 Alfa 145 Cloverleaf '96 Alfa 155, '91 XR2i 2.0 Zetec (sold), '88 BMW 520i slug (sold), '81 Escort Mk3 Project, '68 Mk1 Escort Estate, Berlingo Parts Chaser.
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Oct 26, 2014 12:00:48 GMT
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Hi, sorry gents, that,s the dangers of posting while under the influence of alcohol. I was told that LPG does to diesel, what nitrous does to petrol. so as you say not sure that's a solution. I have just been thinking what about approaching this from the other direction, improve the cooling system so that cooler water comes into the engine and so cools it better or give the head its own supply of coolant?
Colin
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