Mid 20s boost IDI !

[gamudslinger88]

Also I am currious to know if you can take more than 40 off a set of pistons. I live in georgia so we see 20 above at the coldest. would the piston be too thin at 50 or 60 thou.?

 

[Agnem]

Dave, Check the sticky at the top of this forum for our annual IDI gathering, or click the link in my sig. It's definitely in your neck of the woods. We'd love to see you there. Thanks for the info, and yes if your interested in a Moose Pump, shoot me a PM.

 

[Ironman03R]

I will agree that wraping the turbo and pipes will get more boost. I just did this, I wrapped everything but the manifolds with 2"X1/8" heat wrap and secured it w/ SS zipties. I have more boost than I did before, and less lag. I also painted the lower pipe to keep the wrap from rotting out. Every time I have checked it its been dry.
Now I start making boost @1000 and have 5-6psi at 2K unloaded.

 

[Optikalillushun]

when i go turbo im gunna have a spare set of manifolds ceramic coated, all the up and down pipes coated and probaly wrap them as well.

 

[FordGuy100]

when i go turbo im gunna have a spare set of manifolds ceramic coated, all the up and down pipes coated and probaly wrap them as well.

Ditto, I will eventually do that.

I think I have some boost leaks, as it wont make boost at 1000rpm's for me. If I get on it in 4th gear at 100rpm's it will start making boost by about 1150-1200rpm's, and then by 2000rpm's I'll have 5-6psi of boost.

 

[Dave Sponaugle]

A bit more info for you.
Ken at DPS has milled 120 thou off a set of pistons with the intention of more boost, probably with his twin turbo setup.
The only problems he had was getting it started, even when the temps were warm.
120 thou should drop the compression to somewhere in the 16 to 1 area.
80 thou puts you in the 18 to 1 neighborhood, close to what a Stroke runs in stock form.

I will also say that milling the pistons does drop the bottom end torque a little until the turbo starts spooling.
Not something that you would normally notice, but with the weighs I pull and the terrain I live in, I did notice it when starting out going uphill.
As soon as the turbo starts spooling that torque drop is changed the other direction though.


As for the pipe wrap, while the engine was down I painted everything with ceramic high heat paint.
The crossover pipe, the Y at the rear of the passenger side head and the turbo up pipe are all wrapped with header wrap.
As soon as I installed the wrap I soaked the wrap with high heat ceramic paint by spraying on a very heavy coat of paint, to the point it was about to drip.
I let that set up for several hours in the June sun while working on other things.
Then that evening the parts were dry to the touch, I re wrapped everything with a second layer of wrap.
And once again I applied a very heavy coat of ceramic paint till the wrap was well soaked.
I started with two rolls of wrap, and there was a little left over, so I started about an inch down on the down pipe and went down the pipe till I ran out of wrap, just enough to get below the cab where the down pipe is close to the floorboard.
I also soaked that with ceramic paint till the wrap was very saturated.

I did a low RPM smash the throttle in high gear while pulling a hill a couple weeks ago, as I remember 1200 RPM was where the boost gauge went past 10 PSI, so I can say that keeping as much heat in the exhaust before the turbo did help with low RPM boost since the turbo spools faster.

Running high boost on an IDI does take some extra measures on the exhaust connections between the heads and the turbo and some extra measures on the intake side between the turbo and the heads.
None of those connections were designed to hold pressure when the IDI was developed.
They work rather well until the pressure gets above 20 PSI or so, but above that they will leak.

 

[h2odrx]

Running high boost on an IDI does take some extra measures on the exhaust connections between the heads and the turbo and some extra measures on the intake side between the turbo and the heads.
None of those connections were designed to hold pressure when the IDI was developed.
They work rather well until the pressure gets above 20 PSI or so, but above that they will leak.

What extra measures would you suggest? studs?

 

[RedTruck]

Dave,

I just want to reiterate what a lot of guys have said here. Thanks for taking the time to explain your build with all your troubles, and your success.

Thanks,

Paul

 

[flatlander]

What extra measures would you suggest? studs?

Back up a few posts he explained the steps he took on copper gasket spray on the intake gasket, etc. . .

 

[h2odrx]

Yeah i do remember that now been a few days...

 

[FordGuy100]

Dave, what was the total cost for the last engine, the one in your truck currently? What did the maching cost and all that cost you? Just wondering, this might be something I should look into if its not to much money.

 

[Agnem]

Great information Dave. Thanks much.

 

[geonc]

Dave...AWESOME is all I can offer and now I'm over the thought of a 6.9 in my '96 OBS

You are truly a man of strong convictions
and vision

 

[icanfixall]

About milling 120 thous. off the piston tops. I talked directly with the Mahle engineers about this. They told me 15 to 20 off the tops at the maxium amount. The reason for this is the top ring will be too hot for long life. So I bought a set of low compression pistons and milled 14 thousands off the tops but I did this after I had tested all of them in my block for height out of the block. These pistons come up out of the block a maxium amount of 31 thousands. Mine are all 24 to 26 thousands out of the block and they are ceramic coated with Tech Line CBX. The low comp pistons have the pins machined 10 thousands higher in the pistons. All the Makle idi pistons have a dwck thickness of around 560 to 470 thousands. Taking off 120 thous is really close to 1/8 inch. I would think this would be just for pulling compition or racing. I wouldn't be comfortable running it as a daily driver but I'll be watching how this works out. I can still learn something...

 

[Diesel JD]

What about a custom set of slugs from the Caterpillar factory or somewhere else like that. I'd like a set of custom ones with the big pin boss and the turbo IDI rods. I don't know if I could stomach the costs though...