7.3 Prechamber in 6.9 heads?

[txquigly]

Good evening all, new to this site, but not to Ford IDI motors. I'm building another 6.9, having in mind putting on an old style Hypermax system I have laying around. I was wondering if anyone has put 7.3 prechambers in 6.9 heads to lower the CR a little? Also, will a 7.3 PSD oil cooler (or tube assem.) fit the IDI? Which is the best oil cooler setup? Any input would be appreciated!

Quig

 

[icanfixall]

The precups will fit fine... No need to worry but do change all of them... don't mix and match a set of both in one engine or head... The psd oil cooler ends will not fit our blocks nor will the bundle. At one time we could buy either a non turbo bundle or a turbo bundle. Now all we can get is the turbo bundle.. It has 31 fins per inch so it cools the oil better and international and ford only has to stock one kind of bundle.... What makes you feel the 7.3 cups will lower the compression ratio.... Also welcome to the forum. Its best to ask questions before you attempt repairs on these engines.. We have plenty of experiance with doing most anything to these engines...

 

[txquigly]

I found this in a technical bulletin, I just don't know if would make enough difference to justify the cost.
Precombustion chamber volume -
6.9 = 18.34 cm3
7.3 = 20.42 cm3
My next full build will be based on the factory 7.3 turbo long block, but bored and sleeved back to 6.9 for cyl wall help. Custom cut & coated pistons and fully worked heads. BTW, where do you get the turbo oil cooler bundle you mentioned?

Thanks, Quig

 

[jonathan]

it seems like it would increase it not lower it idk

 

[429idi]

That would lower the c/r to about 20.5 if my calculations are correct. I have thought about doing this myself. It would let you run about 1.5lbs more boost with the same dynamic compression ratio at 1 bar. (16.5 instead of 15)

 

[icanfixall]

Both Ford and international are the only suppliers of any oil cooler bundles now. You may find some listings on ebay too...