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More pwr fr stock hpi s25
- Thread starter Magonsterz
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Chris
Well-Known Member
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- 285
- Location
- Lafayette, Louisiana
Maybe a little late, but I just joined this board so forgive me. hehe
I wrote up my own article based off of that S-25 porting guide...pictures included. Here it is guys. PM me if you want the Word doc.
Here we go with the specs...
The sleeve first:
Brass coated with chrome...easy to grind.
For 160-degree duration raise the top of the exhaust port .012". The top of the port will be ~.530" from the top edge of the sleeve.
For 165-degree duration raise the top of the exhaust port .025". The top of the port will be ~.517" from the top edge of the sleeve.
For 170-degree duration raise the top of the exhaust port .035". The top of the port will be ~.507" from the top edge of the sleeve.
It should be noted that if you go for 170 degrees, then grinding will need to happen on the roof of the exhaust port of the block/case. At this point the port is larger than the opening in the block.
Flow grooves on the transfer ports:
Each transfer port will receive a groove running from the *inner* corner of the transfer port to the bottom of the sleeve angled towards the exhaust port (check the picture)...this is viewed with the exhaust port facing you. It's important to match the blocks' internal angles so this is how to do it. Mark a line on the inner side of each port (nearest the exhaust port) straight down to the bottom of the sleeve. From that line, mark another .220" inward again towards the exhaust port. From this inner line to the inner edge of the transfer port will give you your proper angle. Sounds hard, but is really quite easy. Again reference the pictures.
Bevel on bottoms of boost ports:
Can't put this into words really...check the picture.
Piston skirt notch:
Aluminum part and easy to grind. .540 x .375 is certainly not right...so I'm going with .540 x .175 which will suffice. This is just to clear some room for flow at BDC. Check the picture. You want to center your notch at the wrist pin. Don't get it skewed to one side or the other.
Con-rod knife edging
Aluminum part and easy to grind. Simply put...grind a sharp edge on the connecting rod. Most of the work is already done, so why not finish the job?! Follow the angle already cut into the rod.
Crank timing
This was the hardest for me because there's no good picture to show exactly what to cut! So I just stuck the crank back into the motor housing and rotated the crank to see what was going on. Easy enough, but unlike the other pieces the crank is made of steel and is much harder to grind. You'll need a sharp bit for this part. Again the picture is worth 1000 words.
Remove .098" from the leading edge of the port to increase timing to 210 degrees. Also, smooth out any rough edges you may find inside the port. A mirror finish is *not* needed, but certainly helpful if you wish to spend the extra time. These pictures are un-finished and not polished yet.
Lastly:
Head shims. The (3) shims create excessive clearance. Removing 1 or 2 shims (make sure and check this), will increase compression. If you burn up glow plugs quickly, then replace 1 shim at a time.
I wrote up my own article based off of that S-25 porting guide...pictures included. Here it is guys. PM me if you want the Word doc.
Here we go with the specs...
The sleeve first:
Brass coated with chrome...easy to grind.
For 160-degree duration raise the top of the exhaust port .012". The top of the port will be ~.530" from the top edge of the sleeve.
For 165-degree duration raise the top of the exhaust port .025". The top of the port will be ~.517" from the top edge of the sleeve.
For 170-degree duration raise the top of the exhaust port .035". The top of the port will be ~.507" from the top edge of the sleeve.
It should be noted that if you go for 170 degrees, then grinding will need to happen on the roof of the exhaust port of the block/case. At this point the port is larger than the opening in the block.
Flow grooves on the transfer ports:
Each transfer port will receive a groove running from the *inner* corner of the transfer port to the bottom of the sleeve angled towards the exhaust port (check the picture)...this is viewed with the exhaust port facing you. It's important to match the blocks' internal angles so this is how to do it. Mark a line on the inner side of each port (nearest the exhaust port) straight down to the bottom of the sleeve. From that line, mark another .220" inward again towards the exhaust port. From this inner line to the inner edge of the transfer port will give you your proper angle. Sounds hard, but is really quite easy. Again reference the pictures.
Bevel on bottoms of boost ports:
Can't put this into words really...check the picture.
Piston skirt notch:
Aluminum part and easy to grind. .540 x .375 is certainly not right...so I'm going with .540 x .175 which will suffice. This is just to clear some room for flow at BDC. Check the picture. You want to center your notch at the wrist pin. Don't get it skewed to one side or the other.
Con-rod knife edging
Aluminum part and easy to grind. Simply put...grind a sharp edge on the connecting rod. Most of the work is already done, so why not finish the job?! Follow the angle already cut into the rod.
Crank timing
This was the hardest for me because there's no good picture to show exactly what to cut! So I just stuck the crank back into the motor housing and rotated the crank to see what was going on. Easy enough, but unlike the other pieces the crank is made of steel and is much harder to grind. You'll need a sharp bit for this part. Again the picture is worth 1000 words.
Remove .098" from the leading edge of the port to increase timing to 210 degrees. Also, smooth out any rough edges you may find inside the port. A mirror finish is *not* needed, but certainly helpful if you wish to spend the extra time. These pictures are un-finished and not polished yet.
Lastly:
Head shims. The (3) shims create excessive clearance. Removing 1 or 2 shims (make sure and check this), will increase compression. If you burn up glow plugs quickly, then replace 1 shim at a time.
Chris
Well-Known Member
- Messages
- 285
- Location
- Lafayette, Louisiana
The thing screamed on top-end. I grew up under a rail with a SBC so I just *loved* the sound of that thing making such RPM's. It really did roll man!
I never got to try it with an 086 or similar pipe so it had more I know it...
Chris
Well-Known Member
- Messages
- 285
- Location
- Lafayette, Louisiana
Thanks man!
I should note this was my mock-up job...these were the piston/sleeve I had to damage to remove.
The crank was also unfinished at this point, and for some reason never took pics of the new finished pieces. :duh:
Thanks again!
SunkenMetal
Member
- Messages
- 1,395
- Location
- Houston Texas
Nice Right up Go-To, so yeah i don't think anyone is thinking new guy status.....+Rep
Chris
Well-Known Member
- Messages
- 285
- Location
- Lafayette, Louisiana
How's that rep points stuff work?
I don't mind taking my licks to get to where I need to be...I *am* the new guy here basically. dance kitty
SunkenMetal
Member
- Messages
- 1,395
- Location
- Houston Texas
Here is a link to the explination....https://www.hpisavageforum.com/forums/showthread.php?t=5361
basically we give eachother rep points the little green bar, and use the points to buy gifts for people....
Chris
Well-Known Member
- Messages
- 285
- Location
- Lafayette, Louisiana
Thanks!
Yes, I should've warned people that you can pooch your motor in a hurry if you don't know what you are doing.
These specs are for an S-25 *only* BTW.
Chris
Well-Known Member
- Messages
- 285
- Location
- Lafayette, Louisiana
Thanks. VERY cool!
SunkenMetal
Member
- Messages
- 1,395
- Location
- Houston Texas
No Problem, thats what here to do, help eachother out....
