Bigjohn4300 Posted March 1, 2021 Share Posted March 1, 2021 Ive got some questions, concerning the correlation between boost, egts, gear and load. The truck in question is a 2004 CV 713 with a AI300/Allison 4500/4.64 rears. We recently did the EGR cripple (E-Tech exhaust manifold/full 5 inch exhaust/427 hp injectors and S467 YTS turbo, Pyro and boost gauges. Im much happier with the power of the truck, especially the initial rollout from a dead stop. When she is loaded, I notice that when she hits top gear and speed levels out (60-65), the EGTs get up to 900ish @ 1400-1450 rpms. If I downshift a gear, rpm and boost both increase and EGTs go down to 700-750 range. At WOT it will drop to the high 600s. Is this indicative of the turbo being too large? When we tag the excavator along (82k gross), we stay below 50 and she runs in the 700s. I know i was told to keep egts below 4 digits would be a good goal, so I downshift, or back out of the throttle a tad when it exceeds 900. Am i being too cautious at 900? Would a different (smaller) turbo have better flow at a lower engine rpm and keep egts lower without downshifting? Quote Link to comment https://www.bigmacktrucks.com/topic/66083-turbo-maybe-too-big/ Share on other sites More sharing options...
Joey Mack Posted March 1, 2021 Share Posted March 1, 2021 well, i'm curious.. because to me it sounds fine, but then again, I am not a good study on this, i just knew when I was running a bit hot and would adjust as I went... It' been a while.... looking forward to some more comments just caus' jojo 2 Quote Link to comment https://www.bigmacktrucks.com/topic/66083-turbo-maybe-too-big/#findComment-469802 Share on other sites More sharing options...
Popular Post mrsmackpaul Posted March 2, 2021 Popular Post Share Posted March 2, 2021 I dunno about your truck My stock standard 320 E6 will sit at 600 Celsius all day So I dunno whether your Fahrenheit or Celsius 600 C is 1100 f according to Google So dunno Paul 3 Quote Link to comment https://www.bigmacktrucks.com/topic/66083-turbo-maybe-too-big/#findComment-469803 Share on other sites More sharing options...
BGarofalo Posted March 2, 2021 Share Posted March 2, 2021 Can you clarify where you are measuring EGTS? Pre or post turbo makes a big difference in what is acceptable. Quote Link to comment https://www.bigmacktrucks.com/topic/66083-turbo-maybe-too-big/#findComment-469807 Share on other sites More sharing options...
fjh Posted March 2, 2021 Share Posted March 2, 2021 (edited) Sounds to be working the way it should ! Your observations are What I would expect The exhaust temp going up indicates to me that u have reached the point where the turbo is not producing ENOUGH air for the fuel being feed to cyls taking half a gear is the right thing to do ! if the temp climb is gradual everything is good But If the temp climb is relatively fast then you may have a boost leak! At this point you should see smoke behind you even when you have your foot right in it! Just my opinion Edited March 2, 2021 by fjh 2 Quote Link to comment https://www.bigmacktrucks.com/topic/66083-turbo-maybe-too-big/#findComment-469818 Share on other sites More sharing options...
OldRedMack Posted March 2, 2021 Share Posted March 2, 2021 Looks good to me, your just caught between gears at that range. Crusing rpm with my truck is 1650-1750 at about 600. Quote Link to comment https://www.bigmacktrucks.com/topic/66083-turbo-maybe-too-big/#findComment-469826 Share on other sites More sharing options...
Vmac3 Posted March 2, 2021 Share Posted March 2, 2021 Running too rich will increase exhaust temps. Also if your exhaust system has too much back pressure then you will experience very high exhaust temps. I had several truck over the years where customers were experiencing exhaust temps being too high and found that the baffle inside the muffler would restrict the exhaust flow out. But with your situation it seems normal. V 1 Quote Link to comment https://www.bigmacktrucks.com/topic/66083-turbo-maybe-too-big/#findComment-469847 Share on other sites More sharing options...
fjh Posted March 3, 2021 Share Posted March 3, 2021 Yup All relative ! If you have a restriction on the muffler side its the same result as a boost leak not enough air flow in Or out of the engine! for the most part! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/66083-turbo-maybe-too-big/#findComment-469887 Share on other sites More sharing options...
brettj3876 Posted March 6, 2021 Share Posted March 6, 2021 Your temps are fine. We run a little bit bigger turbo (s475 1.32ar) and have the same temps as you. As long as we keep it above 1400 the pyro stays below 1000. 1650-1700 on a hard pull she's right around 900-950 and on flat ground around 700 Quote Link to comment https://www.bigmacktrucks.com/topic/66083-turbo-maybe-too-big/#findComment-470124 Share on other sites More sharing options...
mrsmackpaul Posted March 12, 2021 Share Posted March 12, 2021 I noticed when out and about in Mrs Mack that on the Pyro guage it says something to the effect of "maximum 600 c°" which is over 1100 f So the 900 that was the original question is as we all thought and according to my Pyro guage perfectly normal and my bog stock 320 coolpower runs at 450 all day which is around 850 and gets up to 600 mark on a long hard pull Paul 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/66083-turbo-maybe-too-big/#findComment-470465 Share on other sites More sharing options...
Bigjohn4300 Posted March 17, 2021 Author Share Posted March 17, 2021 Ok, sounds like she is doing good, i thought she was getting a little too hot, but from the feedback, sounds like she is good. I still may try a slightly smaller turbo to keep the boost up more when she makes the 3-4 and 4-5 shifts, she drops down pretty low and takes a few seconds to build it back on those two, 5-6 isnt bad(smaller step) and your over 50 or so by then and backing out anyway. Quote Link to comment https://www.bigmacktrucks.com/topic/66083-turbo-maybe-too-big/#findComment-470869 Share on other sites More sharing options...
Bigjohn4300 Posted October 28, 2021 Author Share Posted October 28, 2021 On 3/1/2021 at 8:36 PM, BGarofalo said: Can you clarify where you are measuring EGTS? Pre or post turbo makes a big difference in what is acceptable. Post turbo Quote Link to comment https://www.bigmacktrucks.com/topic/66083-turbo-maybe-too-big/#findComment-482036 Share on other sites More sharing options...
Bigjohn4300 Posted October 28, 2021 Author Share Posted October 28, 2021 On 3/12/2021 at 2:10 AM, mrsmackpaul said: I noticed when out and about in Mrs Mack that on the Pyro guage it says something to the effect of "maximum 600 c°" which is over 1100 f So the 900 that was the original question is as we all thought and according to my Pyro guage perfectly normal and my bog stock 320 coolpower runs at 450 all day which is around 850 and gets up to 600 mark on a long hard pull Paul Ok, thanks, i had the recommendation of keeping it below 4 digits (1000f) to be safe but looks like now thats very safe. Quote Link to comment https://www.bigmacktrucks.com/topic/66083-turbo-maybe-too-big/#findComment-482037 Share on other sites More sharing options...
Bigjohn4300 Posted October 28, 2021 Author Share Posted October 28, 2021 On 3/17/2021 at 6:39 AM, Bigjohn4300 said: Ok, sounds like she is doing good, i thought she was getting a little too hot, but from the feedback, sounds like she is good. I still may try a slightly smaller turbo to keep the boost up more when she makes the 3-4 and 4-5 shifts, she drops down pretty low and takes a few seconds to build it back on those two, 5-6 isnt bad(smaller step) and your over 50 or so by then and backing out anyway. I had the TCM tweaked to add about 200 rpms to the 3-4 and 4-5 shifts, much better now! Quote Link to comment https://www.bigmacktrucks.com/topic/66083-turbo-maybe-too-big/#findComment-482038 Share on other sites More sharing options...
Bigjohn4300 Posted October 28, 2021 Author Share Posted October 28, 2021 On 3/6/2021 at 2:23 PM, brettj3876 said: Your temps are fine. We run a little bit bigger turbo (s475 1.32ar) and have the same temps as you. As long as we keep it above 1400 the pyro stays below 1000. 1650-1700 on a hard pull she's right around 900-950 and on flat ground around 700 Thanks, yes she is doing much better after raising the 3-4 and 4-5 shift points about 200 rpms. Quote Link to comment https://www.bigmacktrucks.com/topic/66083-turbo-maybe-too-big/#findComment-482039 Share on other sites More sharing options...
Bigjohn4300 Posted October 28, 2021 Author Share Posted October 28, 2021 On 3/1/2021 at 6:05 PM, mrsmackpaul said: I dunno about your truck My stock standard 320 E6 will sit at 600 Celsius all day So I dunno whether your Fahrenheit or Celsius 600 C is 1100 f according to Google So dunno Paul Farenheit Quote Link to comment https://www.bigmacktrucks.com/topic/66083-turbo-maybe-too-big/#findComment-482040 Share on other sites More sharing options...
Bigjohn4300 Posted October 28, 2021 Author Share Posted October 28, 2021 On 3/2/2021 at 8:32 AM, fjh said: Sounds to be working the way it should ! Your observations are What I would expect The exhaust temp going up indicates to me that u have reached the point where the turbo is not producing ENOUGH air for the fuel being feed to cyls taking half a gear is the right thing to do ! if the temp climb is gradual everything is good But If the temp climb is relatively fast then you may have a boost leak! At this point you should see smoke behind you even when you have your foot right in it! Just my opinion Agree that a half gear would have been nice, but the 4500RDS has some pretty big steps between 3rd and 4th and 5th, so we had it tweaked to hold each gear another 200 rpms at mid to 3/4 throttle ranges before shifting, holds boost good, egts stay below 1000 1 Quote Link to comment https://www.bigmacktrucks.com/topic/66083-turbo-maybe-too-big/#findComment-482041 Share on other sites More sharing options...
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