• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

porting precups

HANK1948

HANK1948

New Member
Messages
35
Reaction score
0
Location
Cohoctah, Michigan
After I bought the 6.5 N/A motor I noticed the precups were small(squares).
I have circles and my brother has some heads with diamonds. I started measuring the ports of the cups and found that the only difference were the width of the slot. The squares were .57 the circles were .625 and the diamonds were .700 so I took my squares and machined them to .75-.76 wide, hopefully
make more power.
 

Attachments

  • IMG00096.jpg
    IMG00096.jpg
    45.3 KB · Views: 134
  • IMG00098.jpg
    IMG00098.jpg
    28.4 KB · Views: 124
Cool man! Let us know what happens.

Just so you know, there is now a 6.5 performance area, need to back up to engine selection and you'll se it.
 
Coooooollll...I have heard about guys swapping heads like crazy, just to get the diamond precups, but I've never seen anyone actually modify the precups!

Nice looking machine you got too!
 
Could I suggest having them extrude honed to radius the edges and to smooth the interior transition (after machining)?

Hey when it's someone elses coin, I go all in!:thumbsup:

Regards,
 
Goldsburg said:
Could I suggest having them extrude honed to radius the edges and to smooth the interior transition (after machining)?

Hey when it's someone elses coin, I go all in!:thumbsup:

Regards,
Click to expand...

After I machined the shape I smoothed the transition with a pencil grinder then I sand blasted the port with a very aggressive grit and that smoothed out all the edges. Iam a machinist there is no such thing as a sharp corner we deburr or chamfer or radius everything:D
 
HANK1948 said:
After I machined the shape I smoothed the transition with a pencil grinder then I sand blasted the port with a very aggressive grit and that smoothed out all the edges. Iam a machinist there is no such thing as a sharp corner we deburr or chamfer or radius everything:D
Click to expand...

This tells me that you do quality work and have been doing this for a while!:thumbsup:

I wish that I knew more machinists like you...

Regards,
 
I took her for a good ride today and did a couple of 0-60mph blasts and WOW this thing pull like a raped ape all the way through, and when it gets close to 50 it seems to pull even harder. I dont even have the ATT turbo on it yet, Dennis was going to get one prepped tonight.

So when I get the turbo I cant wait this should hold its own with a Dmax:D
The last time I drove this it didnt pull like this, so the only thing thats a different is the precups.

So before I pull my GM turbo off I will hook my 8000 lbs Travel Trailer up and do a couple 0-60 blasts with it and time it and do the same with the ATT and see the difference!
 
Well, question is, how much is too much? Should try making them even larger if you have an old set kicking about... They limited the size of the pre-cups due to emissions I believe.

Obvoiusly not to many (none?) of us here are worried about the E-Word :)

Also read that the smaller pre-cups yielded in less power but more MPG. IE, 6.2 style.

MPG can be controlled by your right foot, however, easier said than done.
 
Matt Bachand said:
obvoiusly not to many (none?) of us here are worried about the E-Word :)

Also read that the smaller pre-cups yielded in less power but more MPG. IE, 6.2 style.

MPG can be controlled by your right foot, however, easier said than done.
Click to expand...

Exactly the 82 6.2's had the best milage but the slowest, very small pre cups

Emissions, when I am towing 20,000 lbs thats the least of my worries the more power the better:thumbsup:
 
HANK1948 said:
Exactly the 82 6.2's had the best milage but the slowest, very small pre cups

Emissions, when I am towing 20,000 lbs thats the least of my worries the more power the better:thumbsup:
Click to expand...

How much do you think is too much? How much more meat was in there for boring out?
 
You must log in or register to reply here.
Back
Top