Does anyone know what would be considered normal cat temperatures at WOT and what would be high Thanks
What are you looking for? I'll try to get some logs tomorrow. Pick a few rpms. I'll try holding there on fairly level ground. Then maybe some other scenarios? like WOT through a couple of gears? I watched them a long time ago but got what I thought were high readings. I can't remember but as high as 1450 and maybe higher sometimes. Anyway my understanding was that EGT was more of a monitor thing. Like you tune your engine and note the EGT at optimum. After that or after mods you want to adjust to get to the same or if it just changes you know something's wrong or it's time for a tune up.
I have read some of your old posts where you said that when you were getting on it that it went up into the 1700's. I had logged Cat Temps and EGT with the Diablo and got around mid 1700's and was wondering if it was normal, it seemed high but maybe not
Ok, I got some logs. One thing was that I looked at settings on the PC where you configure the log set and there were two PIDs for PreCAT and PostCAT temps. Then when I went to leave in the car I figured I'd just configure the logging on the device and those parameters weren't there. What was there was CAT temp Bank 1 Sensor 1. So I did the logs with that. If it's actually monitoring CAT temp them I'd expect that to be higher than EGT right before the CATs due to the catalytic reaction going on in there. I'll try configuring PreCAT temp on the pc and download the profile to the DashHawk but I suspect they may show as N/A on the device. They did have some inconsistencies on the last Beta between the PC and the device but maybe it's just a menu thing on the device firmware and not that it didn't show those after identifying the car and deciding they weren't applicable. anyway... Started logging right out of the driveway with the engine cold. I was making my way over to the freeway on 25-35 mph side streets. Engine is all warmed up now and we're crusing about 70 mph on the freeway. Here is the detail on the one short WOT burst in the above. Continuing on the freeway I did a few short WOT bursts in fairly close succession. Picked up a few things at the store and this is on the way back. Another moderate WOT burst.
Thanks that looks about what I get also on the Diablo, my cord is broke on my dashawk, I need to get a new one, I'd like to see if the temp is the same on both sides but the Diablo doesn't do bank 1and 2 it just says cat temp
Yea, DashHawk has both sides but I'm wondering just how the PCM gets this number? When I had my cats off I didn't seen any wires coming out of anything but the narrowband sensors. So where is the temperature gauge?
Dave, Al, Here's what I found so far. First off I do run a EGT gage and the probe is located at the collector. In open loop prior to the car reaching operating temps. The calulated value that the Preditor reads is incorrect as far as EGT temps. I do suspect it is true and correct as far as the preheater function of the sensor though. After reaching operating temps, the two values are within 50-100 degrees at all times. And of course just to point something out, the readings are a calculated value and not a true measurement. Not, here's where it gets interesting. When I ran my comp 268 camp, my EGT's averaged between 900-1100 degrees for normal driving. When I switched to my Maxhell cam with a large amount of overlap, my temps skyrocketed to 1300-1500. We tried a little bit of tuning to bring these back into what I considered a safe value. And it worked to a certain point, but not did not entirely eliminate the (IMO) issue. After I switched to the Spartan cam, which by the way has much less over-lap but still more then the 268. My temps now average between 1100-1300. I find this interesting that with more over-lap the temps increase when logic would seem to dictate a decrease in temps. Now to date, the highest EGT reading I've seen is 1600 degrees (with the maxhell) which had me sucking up the leather. But, I did tear down the motor not long after that and did not see any related potential damage. BTW, these reading are all in closed loop. Now I'm know the basic specs of Al's cam and I feel his very high readings are directly related. BUT, will it cause a problem. I don't know. I get differing opinions about what a safe operating level actually is.
Al I really can't say I remember looking for that during the shift.........hahahaha!. I've been a tad more concerned with my AF's then anything else. And besides, with my PLX unit. I have the values set in there to compare my AF's against my EGTs and warn me if I'm detonating. Not that I know if it really works.......but it sure sounds good huh. :grin:
I just watched a log where basicaly cruising on the highway between 65-70mph and around 2000 rpm EGT's were high 1400's and the cat temps at times were 200 degrees cooler and around 25-35mph it went from 1250-1350, and cat temps were around the same
Bringing back up an old thread...have we learned anything else on this? My WOT temps were topping 1800...I pulled some timing and added a little fuel...was seeing 13.0 AFR...Haven't rechecked yet though.
Holy crap! I completely forgot all about this... in fact, I have no recollection of it at all (only that CAM was going to do a write-up on it some time :grin. I am still way interested. I don't remember that last response either. Wouldn't it make sense that you're likely to see higher temps in the collector with more cam overlap? Isn't there likely to be some combustion still happening as the previous charge gets flushed out the exhaust? I would expect the temp difference due to overlap to be less if measured at the exhaust port? There's some cooling going on as the gases get to the collector? With more overlap you're getting some combustion still happening in the header and so higher temps measured at the collector (compared to the same chamber temps and less/no overlap). If you measured at the exhaust port I would expect the reading to be closer to the chamber temp and less difference with overlap or not. Of course, measuring is not easy to compare. At the port you're getting a significant fluctuation at each exhaust stroke and cooling inbetween. At the collector you have 4 pulses in the same amount of time so less fluctuation but cooling in the header getting there. Also it's more of an average temp for the 4 cylinders and isn't likely to catch a problem or difference happening in just one of the cylinders. I'll have to get some more logs now and see if the modeled readings differ at all between bank 1 and 2. (DashDAQ now so the logs won't be quite as pretty (LogWorks 3) as the previous DashHawk logs).
old cam overlap @ .050" -4.49 new cam overlap @ .050" -.52 I'm seeing higher temp numbers now...although I'm far from tuned, i wasn't with the other cam either.
i know with my current set up, i see cat temps ranging from 1100 - 1400 during "normal" driving..... just at 1600 underwot conditions..... i have yet to install my egt gauge, but my understanding is that the cat temps, albeit calculated, are relatively close....
I gotta figure out why i'm pulling 8 degrees of KR at WOT with 12.4 AFR and 20 degrees of timing as target. I may have more compression than I thought, need to run some race gas and see what happens.
