Bushy

Guys, I'd like to run a survey of the EGT's we're seeing on our trucks...<br>Can you do a couple quick tests and post your results ???<br><br>First, state what your max governed speed is during the test.<br>Second, make sure your signature show's you current set-up.<br><br>From a normal (easy) start, up thru 4th gear for the stick guys (4th is 1:1 I believe) and hold till governed speed .....<br>EGT= *F?<br><br>From a wild hard-butt pull thru the gears into 4th right up to governed speed.... <br>EGT= *F?<br><br>Auto guys duplicate this using 3rd gear as your top gear...(1:1)<br><br>Do you see a point were the EGT's rate of climb jumps beyond what you'd call a &quot;steady easy climb&quot; ??<br>Is there a difference between the two types of runs?<br>If you can remain at WOT in 1:1 ratio, does your EGT's stabilize at a max *F or does it start to drop?<br>If it drops how much?<br><br>Thanks guys,, I'm doing a bit 'O research here and any help is appreciated.<br><br>I think jbolt did some drive pressure tests if I remember right.... have any of you guys done this on your trucks...??<br><br>BTW, Jbolt, can you tell me what type of fitting/pressure line you used to do this... It couldn't have been normal plastic boost line... way too hot for that I'd think..<br><br>Thanks guys, I really appreciate your time and tinkering...<br><br>Bob.

Redleg

Bob, if I understand everything, I run W.O.T. all the time on the freeway. I commute an hour to work. Truck tops out at 80-81 on level. EGT stays at 950*, Boost around 14 I think. Both go up with a grade, egt drops some going down a grade, boost goes right to the basement. Stomping on it from 0, I never saw it get past 1150*/24-25 psi. As speed increases, boost comes down, EGT drops to the 950 after topping out. Regular accelleration, the needles jump right up as well initially, but tend to follow accelleration til I reach cruising speed. <br><br>Haven't pulled a load yet. No overdrive. No intercooler. Oversize headache rache to catch the wind. 4:10 gears I believe. No blue wool or flightless, aquatic birds.<br><br>What did I forget?<br>Don

Jbolt001

Bob-<br><br>I have not done pressure tests. I did some air temp tests pre and post intercooler using a thermocouple mounted in a boot. Those tests were not accurate due to the slow response time of the thermo couple I used. I also had problems with the fitting blowing out of the boot at WOT. I now have a faster TC and better mounting method but I have not taken the time to do any more testing.<br><br>Are you wanting to measure pressure loss across the intercooler or pressure at the exhaust manifold?<br><br>Jay

Lil Dog

I'll have to be more scientific Bushy but usuall I can't get to full boost or EGT in 4th gear empty. Max so far is around 1100°F at about 2800 Rpm and 24 PSI boost. But this is at an ambient temp of about 18°C. I haven't tried at high summer temps yet.<br><br>I do notice that with my setup, with my trailer, up a slow grade. If I am over-geared and under 1500 RPM I can get 15 PSI boost but EGT is swinging up to 1000 fast. As RPMS increase the EGT goes down under the same load. Too much fuel...LOL...<br><br>In 2 weeks I will be towing a 27' trailer for my move to the central country and should be a better test. I will post my results..<br><br> Jbolt:<br>This is the expensive way, but you really need to use RTD's not TC's to get a quicker temperature measurement. Problem is RTD's usually run for about $250 a sensor and $1000 for the readout.. [undecided]<br><br>J-eh

Holsteinman

[quote author=Redleg link=board=9;threadid=15936;start=0#149699 date=1055749232]<br> <br><br>Haven't pulled a load yet. No overdrive. No intercooler. Oversize headache rache to catch the wind. 4:10 gears I believe. No blue wool or flightless, aquatic birds.<br><br>What did I forget?<br>Don <br>[/quote]Don, If your truck came from the factory with the 3 speed auto it would have the 3.07 diff gears. As far as I know 3.07 is the only gear you could get with the 3 speed. If you had a 5 speed you could get 3.54 or 4.10 gears. Don I do not know what size tires you have but with 4.10 gears you would be lucky to do 60mph. With 4.10 gears doing 80mph and lets say 32&quot; tall tires you would be turning something like 3500 rpm on the engine. <br><br>Paul

formula

I posted a while back with results of drive pressure readings and how it was relating to charger efficiency. That was with a H1C and a 14cm wastegated housing. Above 25psi boost, the drive pressure started to climb rapidly.<br><br>With the PDR HX35 I had run a 14cm, which turned out to make EGT rise too fast and too far. I went back to the 18.5cm and EGT is much better and mid and top end power is much improved. Now, as for how high EGT am I seeing......If I mash foot to floor from a stop, by the time I run into the governor at 2800rpm, I'm getting to about 1400 deg. If I drop it into OD and keep on it, it'll get to about 1450 and then start to drop back as I hit about 95mph. Today I held it WFO on the highway in OD, speedo burried 100+, 1050 deg, 30psi, 2750rpm.<br><br>Here is an interesting bit of info that I feel goes too often without consideration........ You all notice that if you run the engine at too low an rpm that your egt will be high and you won't have any power. There are a couple of reasons for this. First, and most importantly, the turbocharger is not operating efficiently. It needs airflow to make boost, efficient boost at that. So, if you see that you're getting 15psi of boost at 1500rpm, that's no where near the air that you're getting with 15psi @ 2500rpm. Next is the timing advance mechanism in the injector pump. This mechanism advances the injection timing as a function of engine speed. It works like this.....as rpm increases, the internal supply pump pressure increases. As the supply pump pressure increases, it forces the timing piston on the bottom of the pump to move against it's spring. As the piston moves, it contacts a lever that is attached to the cam roller ring. The cam roller ring is rotated against the direction of pump rotation, thus the start of injection timing is advanced. This has the exact same effect as when you turn the pump to advance the base timing. Now, this advance mechanism is at max travel some point after 2000 engine rpm. So, if you're below this rpm, then you'll see higher egts due to less than full timing advance.<br><br>Oh, and another thing to add to the pile...... boost threshold vs. lag. Sometimes lag is mistaken for being below the boost threshold rpm. In order for a turbo to make any boost at all, it requires a particular exhaust gas flow. The minimum rpm at which you can effectively produce boost is thus the boost threshold. Since I've got an auto, it's not as noticable, but I can't produce much boost at all below 1400rpm. So, the fact that if I hit the throttle from an idle and have to wait for boost isn't really lag, because the engine isn't flowing enough air to spool the turbo in the first place. If I'm cruising down the road at 2000rpm with no boost and then hammer down, the brief time I have to wait for the turbo to spool is really what lag is.<br><br>With my current setup, I keep OD locked out below 50mph. Conditions permitting, I like to run the engine at 1800+ rpm at all times.<br><br>OK, so I got a bit off topic :P <br><br>Sean

PumpDaddy

I've seen 1150, unloaded, but nailed, up hill, 85 MHp, and backed out of it, just to by a dummy that wouldn't move over. Had around 4900# in the bed last week and saw 1200 pulling a hill coming back from MS, but it was nailed again. MY QUESTION is who is going to pay for the speeding ticket if I mash it to the floor and hold it , I'd LOVE to

Bushy

Hey, great response for only one day ... thanks guys.....

Now formula, you're on the same road as me you raskal...
Lag and no drive pressure ARE often confused or missused..

I'm looking at a few things,.. drive pressure(s) at the turbo inlet vs Boost with #'s up into the 40+ PSI boost range.
Second, how much boost differential is there across a NON-LEAKING intercooler, and how does that relate to drive pressure(s)/EGT's.

Have any of you bothered to go to the work of porting/relieving the stock exhaust manifold?? or the inlet of the exhaust housing???

hey formula, why did you go to the 18.5cm rather than the 16cm??

so many questions, so little time....

Bob ~ Pastor of Our Lady Of Acceleration Church..

Bob.

formula

[quote author=Bushy link=board=9;threadid=15936;start=0#150090 date=1055826435]<br><br>Now formula, you're on the same road as me you raskal...<br>Lag and no drive pressure ARE often confused or missused..<br><br><br>hey formula, why did you go to the 18.5cm rather than the 16cm??<br>[/quote]<br>Ah, but Bob, shouldn't I be asking you why you have not tried out a 18.5cm? <br>Well, I needed something bigger because the 14cm was running too hot, even with the wastegate open full. I chose to use the 18.5cm because I had one sitting in my garage. It now runs much better on mid and top end. I think I'll be keeping this setup for a while, it is working out quite well. If someone wants to lend me a 16cm I'd give it a try and post my results.<br><br>Sean

Redleg

[quote author=Holsteinman link=board=9;threadid=15936;start=0#149899 date=1055799295]<br>[quote author=Redleg link=board=9;threadid=15936;start=0#149699 date=1055749232]<br> <br><br>Haven't pulled a load yet. No overdrive. No intercooler. Oversize headache rache to catch the wind. 4:10 gears I believe. No blue wool or flightless, aquatic birds.<br><br>What did I forget?<br>Don <br>[/quote]Don, If your truck came from the factory with the 3 speed auto it would have the 3.07 diff gears. As far as I know 3.07 is the only gear you could get with the 3 speed. If you had a 5 speed you could get 3.54 or 4.10 gears. Don I do not know what size tires you have but with 4.10 gears you would be lucky to do 60mph. With 4.10 gears doing 80mph and lets say 32&quot; tall tires you would be turning something like 3500 rpm on the engine. <br><br>Paul<br>[/quote]<br>3.07.... and the mileage I get???? And no, I don't drive like a bandit all the time. The tags under the hood and door are gone, so I can't check that way. My truck was a cab and chassis though, wonder if maybe 3.54 was offered? I'm running 235's now. Before, with 215's and no mods, it might get close to 80 on level, but took a week and a day to get there.

furious70

AFAIK 3.07 with the 3 speed was it.<br><br>Can somebody give me a treatise on exhaust psi vs. boost psi in a diesel motor? I have a good understanding of how they relate in a gas motor, and what exh psi to run for a given result, but am unsure if the lack of a throttle blade makes the discussion different for a diesel?

Monty

First, state what your max governed speed is during the test.
Second, make sure your signature show's you current set-up.

max governed speed: 2950


From a wild hard-butt pull thru the gears into 4th right up to governed speed....
EGT= *F?

1350

If you can remain at WOT in 1:1 ratio, does your EGT's stabilize at a max *F or does it start to drop?
If it drops how much?

no, stays at a steady 1300-1350

formula

[quote author=furious70 link=board=9;threadid=15936;start=0#150310 date=1055880081]<br>AFAIK 3.07 with the 3 speed was it.<br><br>Can somebody give me a treatise on exhaust psi vs. boost psi in a diesel motor? I have a good understanding of how they relate in a gas motor, and what exh psi to run for a given result, but am unsure if the lack of a throttle blade makes the discussion different for a diesel?<br>[/quote]<br><br>It's a similar scenario, given that you're using exhaust gas turbocharging on both engines. You always want to try to achieve a boost:drive pressure ratio of 1:1 or greater. Detonation is not much of a concern as it is in a gasser due to the fact that a diesel engine only compresses air. Basically, though, what it comes down to is that in order to make power you need to burn fuel. To burn that fuel, you need air. More fuel = more air = more boost. (aside from flow enhancements such as head porting, etc.) How much air you need will determine what kind of turbocharger setup you will have to run.<br><br>Sean

Bushy

I need Way More Air.......<br><br><br>As for boost psi/drive psi etc.... one sucks and the other blows.... sorta...<br><br>Hey formula, I'm &quot;air challenged&quot; at the moment... ;D

Jbolt001

Hey Bob will this do?