19 psi and 1000 degree EGT

[david85]

I haven't seen the rotating parts of a 6.2/6.5 but I did get as far as the heads on a 6.5 and they felt like something you would find on a small block gasser. Seriously, just picking them up, it felt about the same weight as the heads in my F150's 302 gasser. I dread having to lift a 6.9 head off the ground.

It's a crime that so few have tried to build a serious engine out of the IH series IDIs because we know they have at least as much meat in them as the chevy/detroit IDIs.

 

[hce]

Hot rod had a little questions and answers with Heath diesels on 6.5/6.2. The reason he gave for the increase in compression ratio was to force more the air into the precup.
Given the above reasoning this is how I see it. The more air in the precup the more air available for combusion. In an idi you want almost all the air in the precup not below. Lowering the compression ratio by milling pistons will take air out of the precup, and put it in the cylinder. Air in the cylinder does not contribute to the burning of diesel in the precup.
To add to the confusion if we take a 21:1 cr engine at 10 psi of boost effective cr is 35:1
If we drop this to 19:1 it only takes 13 psi of boost to bring it back to an effective cr of 35:1 given intake charge temp, and adiabatic efficiency remains constant. There is more air, but is where it needs to be?

 

[phazertwo]

To answer the internal compression pressure... Yes... Boost increases this pressure and it does this lots. I read this somewhere but can't really recall exactly what it was but.... I think it said that for each 5 lbs of boost increase the pressure in the cylinders in increased by 1000 lbs.... I don't have any proof of this nor do I recall where I read this. Can any mathamaticions calulate this running pressure.... I wonder what the internal pressure is on a top fuel drag motor running 8000 hp and all that boost and type of fuel.... If our turbo can boost to 275 hp at 12 lbs then what is the top fuel motor doing... I do understand the flow thru our heads and the top fuel heads are way differant plus... They are not idi heads. I understand they run a spark plug but its only effective about 300 ft down the track. Then they burn off and the motor lites off by a glow plug effect....

Not a physics major but I will give it a shot.

This is my guess on how to calculate the pressure in the cylinder at TDC, with NO diesel.

So here in Denver we are at 5280ft which means that atmospheric pressure is 12.1psi. (sea level is 14.7psi). So with a NA engine I have 12.1psi x CR. Thats 12.1psi x 22.5= 272.3 psi

Now a turbo boosting at 10 psi
10psi+12.1psi x 22.5= 497.3 psi

15 psi
15psi+12.1psi x 22.5= 609.75 psi

Keep in mind that this is the force WITH OUT DIESEL!!! When the Diesel ignites it sees HUGE pressure increase! IF this is right, than its just a good idea of how much pressure turbo boost actually adds.

PZ

 

[oldmisterbill]

ok, I can appreciate you pushing trucks until they die a miserable death.... thats fine.
When I was younger I killed a few engines and broke a few transmissions. That 9000rpm drop of the clutch might have been the problem.... we'll never know since we can't actually find it or the flywheel....

Just please do me a favor Mr Young. When a new guy comes here and asks how far he can push things like timing, boost, egts, rpms, etc.... please do not speak with the authority of "I been doing it forever" (which roughly translates to, I've had this truck for 4 months and it's still running!) It's annoying, misleading, and well ****, it's just a bad idea, ok?

That is all I ask.
Thank you very much,
Drew

 

[FordGuy100]

Ah but does a boost gauge measure boost from atmospheric pressure, or from sea level pressure? If a mile has a atmoshperic pressure of 12.1psi, and it started measuring from their, your numbers would be correct. But I think boost gauges work by using sea level pressure, where sea level is 14.7psi, so 1psi of boost would register at 15.7psi.

 

[phazertwo]

Ah but does a boost gauge measure boost from atmospheric pressure, or from sea level pressure? If a mile has a atmoshperic pressure of 12.1psi, and it started measuring from their, your numbers would be correct. But I think boost gauges work by using sea level pressure, where sea level is 14.7psi, so 1psi of boost would register at 15.7psi.

I am pretty sure that a boost gauge measures pressure above atmospheric, weather it be at sea level, or mile high. It simply measures how much pressure is in the intake vs how much is out side. Same way a pressure gauge works on a air compressor.


PZ

 

[TWeatherford]

Unfortunately how much a 5 psi boost increase increases head pressure is a difficult one to answer. Lots going on.

A boost gauge reads difference between atmospheric and line pressure. If it read absolute pressure the gauge would read 14.7 psi all the time, or slightly less depending on your elevation. Since most read zero its just pressure above atmospheric you're reading.

I ran a few calculations, which I can post when I have access to a scanner, that suggest for ever 5 psi increased boost you'll have 300 more psi in your cylinder at TDC, which corresponds to about 2900 extra pounds pushing on your cylinder for that 5 psi boost increase.

At atmospheric pressure and TDC ~ 900 psi ~ 8500 lbs per cylinder
15 psi TDC ~ 1800 psi ~ 17300 lbs
25 psi TDC ~ 2400 psi ~ 23000 lbs

All of this involves a lot of assumptions, which most problems in real life involve. Don't quote me as being right, this is just what I'm thinking now.

 

[phazertwo]

Are you adding the pressure the diesel creates when it burns, or simply the pressure that the intake air creates?

PZ

 

[TWeatherford]

That is definitely just pressure before ignition. No idea what happens when it combusts.

 

[FordGuy100]

Considering 1 mol of a liquid will expand to 22.4 liters (generally), I would say there would be a great increase.

 

[hce]

That is definitely just pressure before ignition. No idea what happens when it combusts.

If that was the case I do not think my engine would run with injectors poping at 1700psi, Peak combustion pressure are around 2000 psi.
Take a look at this
150 bar = 2100psi
175 bar = 2540psi
200 bar = 2900psi

Top fuels develop around peak 8000 psi peak combustion pressure the exhaust valve is built purposely small so it can open against the 2000 psi left in the cylinder. Our IDI are now where near this.

 

[dyoung14]

On a side note my injectors are set to pop off at 2300


Now time for an update, i pulled the mountain i didnt hit 25 psi like i had hoped to, i only hit 20 but i pulled the hole mountain holding 20psi and had to work really hard to get the EGT's to 1100 degrees, and its 7% grade couple miles long, that was holding it to the floor all the way up the mountain


After that i decided to take my Ram-air intake off, i noticed i lost 2 psi of boost, and EGT's went up by 100-150 degrees

Ram-air dont work huh?

 

[DeepRoots]

on another note Mr Young.... it appears your truck is in dire need of an intercooler.
you'll loose 2-3 psi so it'll make it safer in that regard. It'll drop the egt's, and your power will grow greatly.

Drew

 

[dyoung14]

on another note Mr Young.... it appears your truck is in dire need of an intercooler.
you'll loose 2-3 psi so it'll make it safer in that regard. It'll drop the egt's, and your power will grow greatly.

Drew

I know i would love to find an intercooler i got a buddy of mine looking for one, but i would love even more to upgrade the turbo

 

[Goofyexponent]

I know i would love to find an intercooler i got a buddy of mine looking for one, but i would love even more to upgrade the turbo

I don't know the limits of the IDI....yet.

But if it were me, I would be watching how much air and fuel I put into an engine like the IDI. I would just hate to see you having to drive that PSD . I am not telling you how to drive your truck, and I am not going to start an argument, because it is afterall your truck and you should be able to do with it what you want to.

I am curious as to what your water temperature is while running WOT under high boost. My truck running N/A with the pump adjusted a two or so flats, will get warm if I REALLY hammer onto it. Hell, on a long hill I start to get a little warm due to the clutch fan being a bit on the bad side.

After the ZF swap gets done, I am going to be hounding Mel about his electric fan mod. He says it is the cats meow and I take his word on it. Might as well do a big alternator swap too!