IC 392 Stroker Motor Advice UT Results

cbmind said:
I spoke to Jim this morning. Legend!

He suggested stay away from dreams of a large displacement motor, and focus on moving more air through it. I.e., supercharger.

He suggested a minimum wall thickness of .110". More than that, and you'll get into overheating issues.

He gave a few key details of one 392 build he did, which I believe is Robert Searles' motor.

1. IC392
2. SB400 stock bore pistons @4.125"
3. Dodge slant six rods.
4. Remove as much rotating mass as you can. They realized 20lbs removed! Much of it from going to a forged aluminum piston and removing the bob weights from the connecting rods.
5. Bush the small end of the rods for a BBC wrist pin.
6. Offset grind the crank. The realized a displacement of 427ci.

As for heads, he mentioned MPG Head Service and their CNC porting program for IH heads.

He did say years ago he had the chance to talk to the IH factory engine designer, and that the designer agreed they were raspy motors. The designer said the best numbers they ever saw, wee from putting 304SV head bowls in 392 heads, among other things. These were the heads used on the factory backed Baja racers. That's pretty extreme and sweet at the same time.

I'll call him again soon, and pick his brain.

Thank you Zaed!
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Are these his recommended specs for a supercharger-friendly engine? And is/are there any particular shop or shops in the U.S. who are a good choice for building up such an engine and/or installing a supercharger on such an engine (under an oem hood)?
 
IH man_cave 007-ultra said:
Are these his recommended specs for a supercharger-friendly engine? And is/are there any particular shop or shops in the U.S. who are a good choice for building up such an engine and/or installing a supercharger on such an engine (under an oem hood)?
Click to expand...


I wouldn't say that.

His point about supercharging was that there was more to gain from supercharging, then anything else.

As far as builders, you just have to search. IHPA might do it. I don't know.

I used local enthusiast clubs to fined a machinist. They are managing the bulk of the work of the motor.

You can get on binder planet, and search posts by cycomick. He did a supercharged 345 using an Eaton m90 and multiport fuel injection. Years ago.

Best of luck!
 
Some bench racing cam selection results included.

Not bad for an old ag water pump cornfield motor.

CID is around 440.

Compression 10:1.

2" long tube headers.

411HP/ 560TQ NA. Absolute torque monster😁.

Steady climb from idle to 4500rpm, then dumps after that like a brick.

I want it to climb to at least 5250, but like everyone else, limited by the heads.

With 7PSI of boost, this brings me to my goal of 600HP or better. 10PSI max puts me near 700HP.
 

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Here's the cam card for the motor. Regrind of an OEM. See how it does.

Lift numbers will increase from higher ratio rockers.

This is one option by Delta Cam in Tacoma, WA.

Another one in the works from Camcraft.
 

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Waiting for parts to finish being coated.

Short block machining is done.

Head work is complete. Just waiting for new rockers to show up to assemble.

Final displacement is 440cid. 10.1CR.
 
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Thank you. Going to be rebuilding mine soon. Waiting to see how yours turns out. What cam did you go with? You get the heads to flow enough? you can message me if its easier. Thank You Roger
 
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