how to make real HP with your IDI

[88 Ford]

88 Ford. I have a feeling you are calling me out .... If so I'm ok with that. Justin has done and will do for the idi what NOBODY else can or will do. Please ask Justin about D young's pump issues that Dennis got from him. I'm not here to destroy Justin's reputation at ALL. You seem enamored with him and what he has accomplished. Many are and that's not a problem for me and should not be an issue for anyone. when you push the limits things are expected to fail. Its how we find the limits. If I was to push the limits like Justin has and has done consistently I would take more readings from every possible location. But he does not as can clearly been seen in your post about installing a different pump and rolling it on the dyno timed by ear. Then finding it was 17 degrees advanced. This was MY concern when he first put power to the ground on the first big build with nothing but a boost gauge connected. I was actually shocked a person would put so much money and time into something and have nothing to show what was going on. No temp, oil pressure or pyro showing any IMPORTANT information. In the end that engine blew a head gasket because of the rush to install it he and his friend installed a piston backwards.

The
ricardo cup was at the bottom on the cylinder instead of at the top where the precup blows into it. He never did post a reason or a pic of that failure. Of course I saw it here as many others did. We all make mistakes and might be embarrassed about the. That is part of life. But please investigate what you are saying. Know your facts. In closing this post I continue to support what Justin does.

Gary, I was not trying to call you out by any means. I was just trying to let it be known that the engine that was dynoed was a near stock engine plus bolt-ons.

Yes Justin Anderson did throw the pump on and wing it but that is not normally how he does things from what I have seen. As for the other circumstance with the head gasket, that was Justin Wheeler aka NMB2, who did that.

As far as respecting what Justin has done for the idi, yes I do really appreciate it. Just like what Mel, Russ, and you have done for the platform before that. There are just different reasons people build their engines the way they do and I can respect that. I apologize if anyone took offense. I was just clarifying some stuff.

 

[79jasper]

there is definitely a lot of good info on this thread. does any one know why an IDI wont start well with lower compression? also has anyone tried to use a compound turbo from a 6.4, or would it not work.

I can't put it any other way, but it's because it's a diesel. Does compression ignition ring a bell?
Iirc, one of the 6.4 turbos is a vgt.

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[88 Ford]

Yes you are correct. The small turbo is a VGT.

 

[The Warden]

does any one know why an IDI wont start well with lower compression?

I can't put it any other way, but it's because it's a diesel. Does compression ignition ring a bell?

It's actually not that simple. 6BT's and PSD's start all the time with a 17:1 compression ratio, whereas an IDI with pistons shaved to bring it from 21:1 to 17:1 will fight tooth and nail to light off.

The way I understand it, an IDI with shaved pistons throws a hissey-fit about starting because of the precombustion chamber design. The glow plug heats up the air in the precup, but doesn't heat up the air between the precup and the piston...and, with shaved pistons, that's quite a bit more air outside of the precup to heat up.

By the way, here's a .WAV file of Ken's 6.9l with shaved pistons to bring it to 17:1 on a cold-start. IIRC that's with glow plugs AND a generous amount of ether. IMHO not practical for a daily driver http://dieselwarden.net/temp/69at17compratio.wav

I've always thought that a way to get around this would be to redesign the precombustion chamber...make it so that the fuel and air still swirl the way they're supposed to, but remove enough material to lower the compression ratio without modifying the pistons any. Doing this would get the compression ratio lower so you could stuff more air into the engine but would hopefully eliminate the cold-start problem. However, doing so would take quite a bit of design engineering and likely more than a little bit of trial and error (are the fuel and air still behaving the way they're supposed to for a complete and clean burn? Is there still enough material that what's there won't burn up?)...and, likely, a lot of $$ as well.

JMHO...

 

[79jasper]

Yeah, but can't really compare idi vs DI.
DI will always start easier.

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[icanfixall]

Any diesel needs temp to ignite the fuel. Its simple science. When you quickly compress air it will climb up in temp. So a fast cranking engine makes more heated air. Read about the temp diesel needs to ignite and you will find it to be 942 degrees. Now concider a very slow cranking engine trying it damndest to make compression which really makes heat. Think again about hand cranking our engine trying to make compressed heated air. It just can't happen. Also this is why a pushed or towed diesel truck will fire right off. Those pistons are making some heat and compression because they are spinning the engine faster than you can with bad starters or cables or mostly dead batteries. Now thats said. About the VGT.. They have a place but so far they have not been adapted to run on an idi. We have no way to control the gates. We don't have the computer or the oil pressure source. Could we??? Maybe. But once again we have a simple design and making it complex is not what most here want. We can cam these engines and we can change the governor springs to raise the rpm but that too has some issues. We are slinging lots of weight with the pistons and rods let alone the heavy crank. Just the dynamics of a piece of aluminum in motion suddenly stopping and then going the other direction is incredible. At least when the piston reaches tdc it has about 2 degrees of crank rotation where it can rest before it runs down to the bottom dead center which btw is much nicer to the piston because of the larger circle the crank is making. Hope I did not bore anyone with this simple explanation of the dynamics involved in making something run.

 

[79jasper]

But people have been putting the vgt on the 6.2/6.5 with great success for awhile now.
And even 12 valves.

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[88 Ford]

You could also control a VGT with an Arduino board. I have seen that as well.

 

[Koch13351]

Look up 91dirtydiesel on YouTube. He has plenty of videos of his IDI with Holset HE351VE VGT

 

[79jasper]

Yep. If'n I try one out on my powerstroke, that's what I'm using.

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[Ford F834]

The thing is, you can get a dual disc clutch with a NV5600. That would be a decent upgrade is the situation necessitated it. I definitely think you will be alright with a 13" clutch with your setup and RD150 though.

This is an interesting idea, but the real problem here is that you would have to be able to use the dual disc Dodge flywheel. Getting that to bolt up to our crank, match balance it, and then find a way to get the NV5600 to bolt up to the engine and a starter sounds like quite the headache if it's even possible. There may be more options than I realize because of the Cummins Ford conversions out there, but at first glance it looks to me like the juice might not be worth the squeeze. I bought Wheeler's drilled 6.9 SMF and 13" Southbend so we will see if it holds with the 150cc...

 

[Ford F834]

By the way, here's a .WAV file of Ken's 6.9l with shaved pistons to bring it to 17:1 on a cold-start. IIRC that's with glow plugs AND a generous amount of ether. IMHO not practical for a daily driver

Do you know how cold that 'cold-star' was? Are we talking negative digits, frosty morning??? What kind of cold start? And are you saying he was using ether AND glow plugs? Thought that was a big no-no!

 

[79jasper]

There's adapters now to put the NV on a powerstroke, so I'd say it wouldn't take too much to get one on a idi.

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[Ford F834]

There's adapters now to put the NV on a powerstroke, so I'd say it wouldn't take too much to get one on a idi.

I was poking around online and there are actually dual disc clutches for the ZF-6 also.... still the major problem is that we can't use the PSD flywheel.

 

[The Warden]

Yeah, but can't really compare idi vs DI.
DI will always start easier.

That's true, but he was asking why the IDI takes more effort to start, and your first response made it sound like all diesels have the problem.

About the VGT.. They have a place but so far they have not been adapted to run on an idi. We have no way to control the gates. We don't have the computer or the oil pressure source.

I've never really paid much attention to the VGT's that the newer diesel pickups use (other than understanding that you can't lug or run them too lightly for too long without sooting up the vanes), but if memory serves, the VGT that's on my VW TDI is mechanically controlled. It has a boost-actuated lever similar to a wastegate, except it manipulates the vanes instead of opening a wastegate. Does a turbo exist that functions in the same manner but at a larger scale i.e. one big enough to feed our engines? (I should note that this is just a thought exercise for me; I really don't have any interest in making monster power out of an IDI; reliability and fuel efficiency are more important to me)...

Do you know how cold that 'cold-star' was? Are we talking negative digits, frosty morning??? What kind of cold start? And are you saying he was using ether AND glow plugs? Thought that was a big no-no!

It's been a few years, but if memory serves, it was NOT a negative-digit frosty morning. I want to say that the temperature was in the 60's, but again, I'm going off an admittedly poor memory of reading a post from 10+ years ago. However, I'm 99.99% certain that temps were above freezing, and certainly not abnormally cold (I'm a native Californian; take that for what it's worth ). And, you're right that ether and glow plugs together are generally a big no-no, but this was an exception to the rule because it was such a bear to start. On the other hand, this is the same engine that Ken blew the bottom end out of...