Engine/Transmission (1994 - 1998) Advise on EGT Reduction

[BrentL]

Can I get some advise on spending the next dime to manage EGT's on the 12Valve?



I still struggle to control EGT's above elevation of 6,000 feet while

pulling. Next attempts include the following:



1) High Tech Turbo compressor wheel upgrade to 60mm stage II



2) Multi piece Manifold w/improved flow



3) Remove or replace the muffler



4) TAG (Turbo Air Guide)



5) Replace Janetty #4 Fuel Plate



6) Change timing from stock to 15. 5 advanced



Any proven results or advice would be appreciated!

 

[propuller]

Advancing the timing from stock to 15. 5-16. 0 will help reduce egt's alot. I just had this done on my dads 12 valve (97 auto) & had the valves set & i cant believe the differance it made. The upper rpm response is awesome & the egt's dropped at least 200 degrees at wide open throttle.



Kurt

 

[DSiemens]

Ditto on the timing. Advancing will help on EGT reduction. I am using a PDR turbo on a 95 Ram. It spools quite quickly and helps to reduce EGT. You have a 5 inch exhaust with a 16 cm housing so there should be no restriction. I've not used the #4 plate, but I've used a #6 and a #10. If you are changing plates, go with a 10. It is more versatile. Timing adjustment, plate change and turbo mods will certainly help.

 

[britannic]

Above 6000' elevation where you're towing, the oxygen levels are lower and depending on the humidity, EGTs will increase, because there's less oxygen to burn the fuel and cool the cylinder. Timing will become more retarded as the oxygen density decreases, so advancing the timing is an excellent suggestion.



The TAG isn't going to lower your EGTs that much, according to what others are posting about it.



The single manifold has proven to be more than adequate for most applications - testing the Banks twin intake, didn't change things all that much.



For towing, you may prefer the #10 as it's a good match for towing and still gives excellent response and higher tq/hp.



Get the timing done first and then see where you're at.

 

[mikel]

Originally posted by BrentL

Can I get some advise on spending the next dime to manage EGT's on the 12Valve?



*snip*



2) Multi piece Manifold w/improved flow



3) Remove or replace the muffler



*snip*



6) Change timing from stock to 15. 5 advanced



Any proven results or advice would be appreciated!

Done the ATS manifold, didn't make a difference on my truck. Same results with going from 3" factory exhaust to 4". I don't see how just changing the muffler would be any different.



Changing the timing did help. I lost about 150-200 degerees going from stock to 15. 5



I tried the larger 16cm turbo housing, I think the EGT's climb a little slower, but they still get to where I let off, so I don't know if they max out at a lower temp or not.



All my driving is at sea level, sorry I don't have any first-hand experience as to how these things act at 6000 feet.



Good luck,

Mike

 

[BrentL]

Thanks for the input guys. Sounds like the timing adjustment is in order and will help a good deal.



Anyone tried the larger compressor wheel upgrade?

 

[Trizae]

just out of curosity, what does a stock 12 valve run EGT wise



I did my guages after i had the truck timed and the waste gate adjusted and spring kit installed



The highest i have ever seen is about 1225 at 75 mph, fifth gear (3. 55 axle ratio) with 7000lbs behind it,,,,,,,,, pulling a fairly steep grade

 

[SEmerson]

I can bury my 1600 in both trucks.

 

[wsmalley]

You already have all the flow you will ever need with that 5-inch and the straight-muffler. The TAG and multi-piece intake and exhaust are questionable at best. You safest bet as everyone has said is to advance the timing. You should be good with 18-20* or so. Drops EGT's, increases fuel mileage, increases top-end running, etc. The boost drop is probably a copmbination of defueling and your wastegate opening. As far as the compressor wheel, you would be better of waiting until you have the fuel for a larger turbo all around. The reduction would be negligible at best from just a compressor wheel.



Trizae,

1250 sounds about right for a stock truck. As I sit now I can go WOT in top gear, unloaded, and barely get over 1400*.

 

[BrentL]

Timing advance and valve adjustment is on the schedule for tomorrow. Does anyone know what 1/4" advancement is equivalent to in degrees?

 

[britannic]

IMHO and of course YMMV, it's better to be conservative with the timing - 15. 5-16* is easier on the engine and pocketbook over time.



WRT 1/4" adjustment: where are you measuring that? I would strongly recommend measurement of the plunger lift with a dial indicator. to baseline the engine before "guesstimating" the timing.

 

[BrentL]

I'm taking it into the Cummins shop. They say they advance them by 1/4" all the time and they run great that's all the detail I have until I take it in and talk with them in the morning. He said they don't measure the advance in degrees.

 

[britannic]

That's all very well, but they're presuming at least 2 things:



1. The base timing is 100% accurate as set at the factory - but we know better.



2. The timing has never slipped or been adjusted.



Just my 2c.

 

[BrentL]

Cummins says they will set it to factory spec, and then advance from there. I will try to get an answer on how many degrees before they do it. I would think someone there should know!

 

[JoshPeters]

If they tell you they can't tell you degrees, they are on crack. Many of us on here have timing tools, and if you go to Piers web page, he has a plunger lift to degrees advance timing spec page.



Josh

 

[BrentL]

Thanks Josh. I have the timing info printed and I'll take it to Cummins!

 

[britannic]

Sounds like they're just going to use the timing plunger pin in the camshaft gear and maybe use the pump's lockpin to baseline it. I wouldn't want to pay much for someone to do that and in any case, the timing can still be off by as much as +/- 3*.



I tested mine using the factory pin method and found it was 2* retarded from factory (12. 3*) when I rechecked it using true TDC and my dial gauge.

Originally posted by BrentL

Cummins says they will set it to factory spec, and then advance from there. I will try to get an answer on how many degrees before they do it. I would think someone there should know!

 

[Andy Redmond]

1/8" roughly = 1 degree of time on a 9. 25" vibration dampner. So 1/4" = two degrees right? Maybe someone will chime in and give us some geometry/trig. refresher courses if I'm far off.



Cummins often uses the $$$$ Spill-Port method, which is deadly accurate if the tech knows how to use it. Most Cummins places won't time out of data plate specs. for fear of big brother and the epa. Perhaps they are using the 215 spec. , say 13. 5 to 14. 5 on a earlier P pump with less timing per data plate, say 12. 5 for example. Basically a spill-port machine offers pressurized fuel and allows the tech to observe injection pump spill-port closure/opening by watching the fuel stream or lack therof at / near engine tdc while the engine is barred over. It has special adapters that replace # 1 delivery valve. Cummins service literature shows good instructions / illustrations on this method.



Most of us use the dial indicator method as it is portable and more affordable and offers reasonably accurate results if engine tdc is found.



Others use timing tape, piezo adapter (senses fuel pulses in # 1 injection line) and a timing light, then advance/retard appropriate amounts. Also a good method, but perhaps $500 + in good tools.



Pinning the engine and pinning the pump then advancing it (turning engine counterclockwise from tdc, with the gear loose, after backing off engine timing pin or known engine tdc mark) about 3/8" is advancing the timing 2. 5 - 3 deg.



Of course good points were raised, has it been done before, is pin/pin really the data plate's timing (were you at the dataplate spec when starting)? Is the pump tdc (pinned really 12. 5, 14 deg. etc. ) accurate? You don't know. Most that use this method believe their truck to be oe and are pleased with the before truck seemed ok before mods (didn't exhibit low power, white smoke etc. ) and after. They are after several degrees of advance and usually obtain it, if done properly.



Experienced techs can often listen to your engine and tell if its far outta spec retarded or advanced.



Most folks don't produce the ponies to justify the increased cylinder pressures from 18-20 deg. of time IMHO. If your name is Piers, Fulmer or Donnelly et. al none of this may/may not apply!



Good luck, Andy

 

[Turbo Thom]

The only things I did that changed the EGT's was a 14 cm2 housing, 4" exhaust, and a little less throttle. That dropped mine at least 150 degrees. I don't see that timing has ever changed temps to a degree that I could tell it. Maybe it does, I just didn't see it. I can still get it hot if I want to but why would I?



. . Preston. .

 

[blacksheepdiesel]

BrentL,



I didn't see anything in your sig about gsk? Don't know how it would affect egt's but it sure is more fun to drive! Also, I did notice that you have an auxillary trans. What gear(s) and rpm's do you have egt issues?



Trent