heres an interesting question...

[turbonator]

are the gm 6.2l/6.5l pre-combustion cups the same size as the 6.9l/7.3.....

 

[turbonator]

are the gm 6.2l/6.5l pre-combustion the same size as the 6.9l/7.3.....

i know that it was recardo that designed this style chamber, but i am not sure if the pre-cups were the same dimensions between the different engines.... if they are you 6.9/7.3 idi guys might see a huge improvement by using a set of late model 6.5l diamond pre-cups which were available only in 1996-to present... they have a larger "mouth" and are machined down inside to give the 6.5l a comp ratio of 20:5:1....

 

[icanfixall]

Might be something we should be looking into. Maybe this is a question that towcat could answer.... My first set of ported heads had plenty of work done to the precups throats. I may have done too much cleaning up to them...

 

[turbonator]

We have a 6.9L here, that we were thinking of scrapping, I will pull a head and verify the pre-cup dimensioning and post up later.

 

[flareside_thun]

If you don't get around to it I can take some measurements on the 6.9 here at school that's torn down.

 

[icanfixall]

The 6.9 and 7.3 cups are the same. The chevy 6.2 or 6.5 cups are whats getting the interest here...

 

[turbonator]

The 6.9 and 7.3 cups are the same. The chevy 6.2 or 6.5 cups are whats getting the interest here...

what i am wondering is if the pre-cups are the same dimensions to swap from motor to motor...(6.9 to 6.5 or vice-versa)

 

[turbonator]

If you don't get around to it I can take some measurements on the 6.9 here at school that's torn down.

thats a good idea, measure the external outside diameter at the top, and the external out side diameter at the bottom, height, if you want to really impress, do a volumetric measurement, and we will do the same here with a 6.5l turbo pre-cup...

 

[flareside_thun]

I'll see what I can do.....It's my baby for the school to sell and buy another engine to rebuild....I love doin this every once in awhile but couldn't do this all the time.

 

[towcat]

i'll need to find a 6.5 head to ****. unfortunately, I don't have any late model heads to pick through.

 

[flareside_thun]

If no one has a 6.5 head around...I'll make a call and see if he still has that one...probly scrapped by now...

 

[hawaiian808]

Any news?

 

[Agnem]

I have an easy to examine precup in the "cutaway head" that everyone who has been to an IDI Weekend has seen.

You must be registered for see images

 

[flareside_thun]

Can you do that Mel? Instructor won't let me yank the precups out.

 

[Black dawg]

6.5 precup

od at head surface 1.561
od inside the head 1.356
thickness of deck surface of precup.1875
overall thickness height of prechamber .855