Mike B Posted March 22, 2008 Share Posted March 22, 2008 Hi Everyone. Am currently getting the car ready for Marham, replacing an O2 sensor among other things, but I have a specific Q about EGT temps. Currently have the EGT probe placed in the DP... the manifold, turb and DP are heavily heat wrapped, my AFR's at a 3.5k rpm cruise, off boost is 14.1/14.5, full throttle is 10.7 +/- depending on boost level. On the dyno I see no higher than 650 degrees on a long 5th gear run (and motorscope's dyno has a huge run). On the road however I see 650-700 degrees from time to time whist cruising and mild use... and when it's at this temperature and I pull it will climb to 800 after repeated on off track type throttle use. what cruise egts do you guys get and at what afr's? do you get heat soak on heavily wrapped ex systems? The answer is to clear off a section of the manifold and put the sensor there, so I can tell exactly what is going on. To that end is there any danger in electronically welding onto the manifold whilst attached to the car? I'm thinking about ecu and sensor frying.... Link to comment Share on other sites More sharing options...
gledo1970 Posted March 22, 2008 Share Posted March 22, 2008 I'd get the egt probe fitted about 1" from the cylinder head on number one or number six runner as these are usually the weakest cylinders and so will have a higher exhaust temp than the rest. as for the welding the new boss on i would take the manifold off to make sure no swarf gets into the exhaust headers when drilling the hole and the welder will be able to make a much nicer job of welding the boss. if the manifold is stainless steel then it really wants tig welding with the correct rods matched to the manifold. you can use a mig welder to do this but there is more chance of cracking problems in the future Link to comment Share on other sites More sharing options...
gledo1970 Posted March 22, 2008 Share Posted March 22, 2008 also when welding on the car you can put a surge protector on the battery to protect ecu,gauges,radio's etc from current surge from welding Link to comment Share on other sites More sharing options...
Wez Posted March 22, 2008 Share Posted March 22, 2008 How far down the DP is the probe mounted? Cruise AFRs look ok and general rule is normally lose about 200deg through the turbo etc, which means your EGTs may be creeping on the high side. As a comparison my temps are roughly the same but in the collector in the manifold before the turbo. Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted March 22, 2008 Share Posted March 22, 2008 I would also say that if EGTs are reaching 800c then there a little high 150-200c lower is about right for down pipe, if you can drill and tap the exhaust housing of the turbo, that is also a good place, as for welding, i have done quite a lot of it on various cars and never blown an ECU,guess it depends how good condition your welder is, but you never now, if you have aftermarket ECU it might be worth disconnecting it. Link to comment Share on other sites More sharing options...
Mike B Posted March 22, 2008 Author Share Posted March 22, 2008 How far down the DP is the probe mounted? Cruise AFRs look ok and general rule is normally lose about 200deg through the turbo etc, which means your EGTs may be creeping on the high side. Right at the head. 2" behind the exducer. This is what I'm thinkig, but on the motorscope dyno, with maybe a 15 second pull from an idle temp of 300 deg I see 650 max, on repeated runs. Only on cruise where I get 600 will it climb higher. if you have aftermarket ECU it might be worth disconnecting it. I thought this was also a good idea, was my plan. Don't know if I am going to do it, like you say to drill the hole you really need to take the turbo off and that is an uber ball ache with my setup. Changing housings a few times has put me off the job for life, even though I now have the tools and know how. I should have done it last time I changed housing. I have an unreliable O2 ecu sensor at the mo, so when I get a new one I may check temps again, once the ecu has a new pair of eyes, then decide on what to do. Link to comment Share on other sites More sharing options...
jevansio Posted March 22, 2008 Share Posted March 22, 2008 I always thought the 200deg rule was rubbish, I was seeing 850 in the down pipe (2 inches from the turbo), I decided to have the probe mounted in the turbo, I instantly saw 1050deg. Whe my old turbo came off it was white (a sign of being too hot I believe). I guess the only way you'll be happy is to get the probe on the other side of the turbo. Link to comment Share on other sites More sharing options...
Mike B Posted March 23, 2008 Author Share Posted March 23, 2008 I always thought the 200deg rule was rubbish, I was seeing 850 in the down pipe (2 inches from the turbo), I decided to have the probe mounted in the turbo, I instantly saw 1050deg. Whe my old turbo came off it was white (a sign of being too hot I believe). I guess the only way you'll be happy is to get the probe on the other side of the turbo. that doesn't sound good.... was your dp and manifold heavily wrapped? Link to comment Share on other sites More sharing options...
Milton79 Posted March 23, 2008 Share Posted March 23, 2008 what ecu are you running? Link to comment Share on other sites More sharing options...
Mike B Posted March 23, 2008 Author Share Posted March 23, 2008 Vpro on closed loop; self learning. Link to comment Share on other sites More sharing options...
jevansio Posted March 23, 2008 Share Posted March 23, 2008 that doesn't sound good.... was your dp and manifold heavily wrapped? Yes, both are heat wrapped Mike. Link to comment Share on other sites More sharing options...
Wez Posted March 23, 2008 Share Posted March 23, 2008 My DP and heat wrapped and my manifold is cast which tend to hold a bit more heat anyway. Link to comment Share on other sites More sharing options...
Ryan.G Posted March 23, 2008 Share Posted March 23, 2008 Sounds like its too retarded on cruise Mike, At a AFR of 14.1:1 i would expect it to be alot lower. I have mapped some cars to around 15.5:1 - 16:1 on cruise before and they never go over 800c with the sensor in the manifold. Dont you have some kind of wierd ignition trim dial in the car? As i expect it retards globally so where you might have pulled timing for the new turbo its made it now too retarded on cruise Ryan Ryan Link to comment Share on other sites More sharing options...
Ryan.G Posted March 23, 2008 Share Posted March 23, 2008 Also disconnect the Neg side of the battery before doing any welding on the car. I would also remove the ecu to be extra safe as well. Ryan Link to comment Share on other sites More sharing options...
Mike B Posted March 24, 2008 Author Share Posted March 24, 2008 Also disconnect the Neg side of the battery before doing any welding on the car. I would also remove the ecu to be extra safe as well. Ryan Hi Ryan, thanks for that. Yes, I pulled the ign right back as a safety measure as the ECU saw a little det on some high speed dyno runs. Pulling the ign back made no difference to the HP, so I just left it there. I never get more than 650 on a cruise, and ironically 650 on the dyno, but maybe I should retard the thing only when I'm about to give it lots of welly (easy done on a dial in the glove box). I'll try the next time I have it on a long cruise. Thanks for the info, it is much appreciated as always Link to comment Share on other sites More sharing options...
Nic Posted March 24, 2008 Share Posted March 24, 2008 My EGT sensor is in the same place as yours Mike, max I see is around 700 degrees. Link to comment Share on other sites More sharing options...
Mike B Posted March 24, 2008 Author Share Posted March 24, 2008 My EGT sensor is in the same place as yours Mike, max I see is around 700 degrees. thanks Nic, like I say, max i see on the dyno is 650, but if I can get it to 650-700 on cruise, then spend a while at high load then it starts to creep to 800... the only way is to get the sensor shifted really. Link to comment Share on other sites More sharing options...
Wez Posted April 2, 2008 Share Posted April 2, 2008 Just to update on this as I monitored my EGT on a recent motorway journey, when cruising at 80 to 90 leptons my EGTs were a steady 600degC. My EGT probe is mounted before the turbo. Link to comment Share on other sites More sharing options...
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