Turbo Idea

[Ironman03R]

I have a thought...
The limiting factor to these engines is high EGT's so what if a larger turbo was used with a bigger more efficiant compressor, with intercooler of course. I know everyone has their ideas of "Safe" boost levels, but from what I've been readin, 15-25 might be possible with head studs and a turbo thats not workin so hard to make boost that it looses it efficiantcy and super heats the air. Plus some more boost might be possible with water injection. I know a big turbo will make way more boost that a 7.3 could ever use so it would have to have a wastegate.
So I guess my question is will a higher volume of cooler air help to keep EGT's under control or make it worse. Im not in the middle of any extreme build up I'm just throwin ideas out there. There are a lot of engines out there that run way more boost with similar or more compression, I think the internals can handle more than we are givin it.

Opinions?

 

[tonkadoctor]

It can be done. Coller air in and free flowing exhaust can bring down EGTs a lot.

Many things will come into play with higher boost levels to keep things cool enough to not melt pistons

1. charge air temps can be brought back down with intercoolers
2. exhaust needs to get out accomplished with correctly sized exhaust systems
3. Quantity of fuel needs to be higher to make the power and not run too lean which will melt pistons..... accomplished with injectors & injection pump
4. High performance & extreeme performance diesels have lower compression ratios so they can cram more fuel and air into them to avoid lifting the heads because cylinder pressures are too high
5. Timing becomes critical to avoid igniting the mixture too soon and breaking parts

Some guys are even messing with the IDI engine precup chambers to achieve as close to direct injection as possible too to get more power.

 

[dansvan]

How do you run a diesel too lean? Don't they just shut off?

 

[f-two-fiddy]

Turbo design is allmost an art. If you use a larger turbo, especially with a diesel. Your going to run into more turbo lag. Since the diesel turns so slow.

 

[tonkadoctor]

How do you run a diesel too lean? Don't they just shut off?

No it won't shut off unless it isn't getting enough fuel to run. It will blow white or light blue smoke and feel like it has no power.

 

[Ironman03R]

Yeah I figure there would be lots of turbo lag, since I notice it with my factory turbo. Compoumd turbos would be the way to go to avoid that, but there would'nt be much of a point with such low boost pressures.
I wish I had the computer programing know how to set-up a variable turbo from a 6.0. When I was at Ford the diesel tech and I talkked about it, but couldnt figure out a "simple" way to do it.

 

[jauguston]

Too lean is a condition that effects gasoline engines. That condition description is not applicable to a diesel engines. The amount of air in a diesel engine combustion chamber is constant regardless of the amount of fuel injected. There is not a direct connection between the amount of air in the combustion chamber and the amount of fuel.

Jim

 

[93turbo_animal]

agreed you cannot lean out a diesel less fuel just equals less go

 

[swampdigger]

Coincidentally I've been crunching numbers for turbos this morning...

What surprised me, is that our big engines don't flow a lot of air because of the low red-line. A smaller high revving gas engine requires much more air flow.

In other words, larger isn't necessarily better. You have to find the "right" size. If your turbo is sized wrong, lots of things can happen, one of which is it'll generate too much heat, and spike your EGTs.

Also, a turbo will not increase airflow. It increases air pressure. The airflow your engine draws is fixed by features like your cam, intake, heads, displacement, etc. etc.

Interestingly, a near perfect match is a pair of T3s off a standard transmission Ford 2.3 turbo. Hmmm.....

 

[Ironman03R]

I'm thinkin more along the lines of the stock turbo only being efficiant to a certian point, like 7-10 psi. So, what if we had a turbo or turbos that could make higher boost efficiantly, w/o causing extreme air temps before it gets into the cylinders. Higher pressure in cylinders=more air being forced in right?

 

[f-two-fiddy]

You could bore the housing and add a different wheel. Maybe a different pitch.

Like I said, it's allmost an art form. If you look at modified turbo maps, you might find one that'll be suitable for this application

 

[jauguston]

Ironman,

My Hypermax conventional turbo will make 14 psi and do it with a EGT below 1200 degrees. I wouldn't be surprised if their "Pulse" kit would do even better. Take it out of the box and bolt it on.

Jim

 

[Cowboy_Customs]

Ya know, being in the cummins world for the past year here I have picked up quite a bit of knowledge on turbos now. I belive the best combo for our IDI's would be a factory H1C off of the 1st generation cummins trucks. The 1st gen cummins stock turbos are only putting out 15-20 PSI. VERY laggy yes, BUT, with a different exhaust housing that changes greatly. Using the stock compressor side, or even an HTT stage II or III (due to the stock compressors known for surge, which im dealing with now ) and a 14CM or even a 12CM wastgated housing, would be a PERFECT match. IMHO.
I just dont know how well it'll bolt up though. If money allows, I am going to switch out my turbo on the cummins to a Schwitzer s300, and Id be willing to test out fitment of the H1C on my IDI, (having a hard time selling it, I have a perspective buyer, but im kind of reluctant to sell my first diesel)

 

[jauguston]

Ironman,

What is your ultimate goal? Are you looking for more boost than a kit like mine will make or are you looking to cobble something together on the cheap, or do you just like to experiment? I like #3.

Jim

 

[Ironman03R]

I have too much time on my hands at work and think about to many ways to spend my money. I already have a factory turbo and am to the limit of my stock pump. I also have an intercooler on the bench just waitin to get the time to install it. Also planning on some port work when its time. I like to experament with different setups to see what can make more power. I like some of the ideas Im hearing, I have also looked at some cummins turbos, but like I said....I have too much time at work!