Curious to see how well she starts with that low of compression.

 

If I take another .020" off my pistons, it would only be .070" total, and about .055" down in the bore.

I took .080" off NMB2's pistons, and at very worse that could put me even with his numbers and at best about a 1/2 point higher. His truck started just fine, and IIRC even started in warmer weather without GP's. One thing people forget to consider about reducing the compression in these things, is how much faster they spin over. Couple that with a high pop pressure, and I don't think Ill have too much issue with starting.

 

Said everything i was going to say.

 

My only qualm about lowering compression this way on IDIs is decreasing the depth of the swirl bowls on top of the piston. Are you concerned about it at all?

 

I reduced it a lot with the first .050" I took off the top, and the Burn is 100% even on top of the piston, I'll see if I can get some good pictures of the top of a piston. I don't think another .020" will change things much, but we will just have to see. Id be willing to bet the drop in compression will have more of an effect on efficiency than the reduction of the swirl pocket.


As far as the piston goes, Im not doing anything that hasn't been done before. NMB2's IDI was a great engine, the only thing that did it in for him was an oiling issue that wiped out half the engine.


Im more worried about things like HG's, and Piston Structure/Wrist pins with the level im going to be taking this thing to. I think the block with a partial fill, and the main girdle is going to be as strong as it is going to get, The crank speaks for itself, the rods are the same as forged 7.3psd units, the 9/16" studs are leaps and bounds more beefy than the 1/2" 7.3 Stuff, My valve springs are 130lbs on the seat, new valves, Smith bro's Chromoly pushrods. The weak links in there are the Piston (Maybe not), wrist pin (Maybe not, especially with some RPM) and the HG. The HG is the biggest weak link based on its type. Im sure the heads aren't going to lift this time, and the O-rings are going to hold laterally, but what is it going to take to push them beyond those structural braces?

 

There were a few physics guys talking about it somewhere, that removing some of the expansion area would actually help things. That being said, no expansion chamber very obviously doesnt work as we seen in NMB2s build with the wee accident.

 

He was also running fel-pros on that incident as well.


That being said, the swirl pocket actually does something, even as small as NMB2's were, we know that.

 

I didnt even think of that lol

Now hurry up and get this thing together the suspense is killing me lol

 

I have plans for a all-out build someday and one of the items I want to do is filling it. Here's an article on a powerstroke with good pictures on the filling. Wide Open Performance also has some 1000 hp powerstrokes with filled blocks and cryo-treating on the rotating assembly.

 

Hmmm filling it would certainly help prevent cavitation.

 

Yeah, Ive done a bunch of research on it, The only decision left is which brand to use.


Im one of those people who doesn't buy into the snake oil of Cryo-Treating everything in your engine. Cryogenics only improve the grain structure of certain tool steels and chromoly's, and they have very little effect on steel forgings and none on castings. Would it hurt anything, no, but Im not going to waste my money on it.

 

Got the pump cam to the shop yesterday and they are going to probably have it done by Friday. They have to wrangle up all the RQV gov parts and bench it. Its going to be set to 350cc's with a 4k gsk. The Pump will be calibrated with 3000psi pop test nozzles and to keep things consistent with the IDI stuff, .5mm test orifices. It will most definitely need a little tweaking when I get the engine fired.


I also got my head fastener drilling jig burnt out, I just need to layout the holes and machine them for my drill bushings.


I might get a start on pulling the short block apart tomorrow, but that depends how well my other projects go.


I am also reconsidering running compounds at this point as well. I can get a 60/68/.91 and a 71/96/1.32 for less than I can a single FMW 68/83/1.10, so Ill have to think about that.

 

The little bit of reading i did, claimed that cryo actually helped the block, almost like a hard face if you will. Claimed that anywhere there was friction (cylinder) there would be less friction and wear.

 

Yup, keyword is "Claimed"...


That's the biggest issue I have with the whole process. Plenty of people willing to do it, plenty of people making claims, some of which are laughable, and almost no proof. The only substantial proof of cryogenics being fruitful is on things like shafts which are made of tool steels, and the cryogenics actually making a noticeable difference in grain structure, leading to a tougher shaft (Not harder, but more tough or able to take strain) The problem with cryogenics in things like forgings, is the grain structures aren't consistent. Cryogenics does not do anything for the consistency of the grain structures, it only "Softens" (I only use that term because I don't have a better way to describe what it does the the structure) the structure in its existing form.


I was really into the idea of cryogenics a long time ago, I thought it was a process that really helped things based on what I had read. Then I started researching it more, and I found that there are a lot of charlatans pushing it. One in particular likes to post on message boards under different names pushing the glory of cryo. If you actually read what metallurgists have to say on the subject (The scientists, not the salesman at your local heat treating company), The effects of cryogenics are very limited.

 

Are you concerned about any transmission issues with that much torque?