1G Engine Blueprint Data - Help with block and piston/rod combo path forward.

[athlete3344]

Hello,
I'm in the process of rebuilding a 1g block and need some help figuring out if I need to go 0.020 over or not. Additionally, I have a couple sets of pistons, but I'm leaning towards going new with the goal of overbuilding the motor even though I'm only expecting 300-350ish hp. I'd like to leave my options open if I decide to go with a larger turbo.

Cylinders are definitely egged/tapered and will need a minimum of a hone. I'm just not sure what to look at next - PTW gap, ring gaps, etc?.

I also don't know what to look at next for pistons/rods. Any feedback on the Wiseco 6559M855? These were pulled from an engine that had 2 rod bearing failures (previous owner likely rebuilt incorrectly).

Figured I'd make a post while I do some research as well. Thanks in advance for any input.

Procedure:
Set 3-4" mic to 3.3465" after checking calibration (it was dead on).
Zero bore gauge in mic.
Error for both tools +/- 0.0001
Take 3 readings at each cylinder location (top, middle bottom). Each of the 3 readings was at a slightly different area of the cylinder.

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Data:
Numbers are Difference = (Measured Cylinder Bore - Stock Bore)

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Measured Cylinder Bore
Added the above values to stock cylinder bore

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Pistons
I need to remeasure these with my 3-4" mic (I didn't have one at the time).

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[miliman13]

great spreadsheet!!!
these are my numbers if interested I have 85.5mm pistons too same brand mines are 9.0:1, when I looked for your model, I could not find the comp ratio.
to be perfectly honest I don't know what specific clerance your refering to, so heres a few.

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^ screenshot of another thread
Lastly i set my rings to 0.022 on the top and 0.024 on the bottom
I see 150PSI ice cold compression on all 4
at 25psi and 5-6k rpm I make 500 ft-lbs and 530 hp respectively

 

[athlete3344]

Me either - I need to watch a few more Jafro videos but Im mainly looking for next steps. 1st time rebuilding an engine. <3 my speadsheets, thanks!

I think maybe its pick a PTW, check some of the diameters of some potential pistons, and see if theres enough meat in the cylinder walls left to meet those PTW clearances after the hone?

 

[miliman13]

Me either - I need to watch a few more Jafro videos but Im mainly looking for next steps. 1st time rebuilding an engine. <3 my speadsheets, thanks!

I think maybe its pick a PTW, check some of the diameters of some potential pistons, and see if theres enough meat in the cylinder walls left to meet those PTW clearances after the hone?

Sounds good! Jafro is a great source too.

I knew what PTW clearances I wanted, and I made it clear to machines shop, I brought in my pistons so they can then hone it as much as needed to achieve those final 0.00XX values. all these numbers really depend on your intended use. I modeled my engine on the numbers used by veteran 4g63 engine builders-tuners @codeofdastreets

 

[jed344]

Very good data. Most times the bores are like this honestly. If you decide to pick a forged high expansion piston like a weisco, manley ect. These pistons require a much looser PTW then factory. Looking at your data a hone would make the bores straight again and get to the new PTW you would want. We always use a deck plate as that changes too the shape of the bores. This all assumes you have a good machine shop as we have in the past used a shop that left us quite not happy. Told him .0045 and we ended up more like .0045, .0047, .0049, .0053. This motor is still living a good life with a 6466 at over 40 psi but our pursuit of perfection knows .

A little easter egg here but for example weisco says .0035 piston to wall for there pistons. This number has to be even more if you plan to run even more boost/power but it does not tell you this as i recall on the info with the pistons.
Personally i always have done .0040 with any of these pistons as it is loose enough on a full wet block to make 700+ and run quite a lot of boost. When i refreshed these motors everything looked happy.
With even more serious or say a half fill i go to .0045 as again i have myself made just shy of 800 with this ptw on a half filled block and the pistons looked happy when i refreshed it.
.004 PTW the motor may slap for a few seconds on a cold day but then is fine. Larger then that they do tend to slap for longer but thats to be expected.

Ring gap also depends on the goals. Generally on a .0040 motor i will set around .020 and .022. When doing .0045 motor will go more like .022 and .024. The looser we go the more blow by but that's the price to pay to be sure ring gap does not close and touch.
The main clearance with something like a king XP or ACL tri metal we shoot for .002 to .0022 ideally.
I always make sure the rod oil clearance ends up looser then the mains. Most of the rod manufactures require .002 minimum oil clearance anyway. Usually end up around .0022-.0025. Sometimes a bit more.
These are motors we run with no squirters or balance shafts and 20w50.
Always check the rod big end side clearance. Many forget this and if this is to tight the oil cannot escape fast enough and it causes issues.

There is much more we do and have our preference with from over the last 15 years of experience but least these values for these specific things have not served us wrong yet anyway. I would have to grab a piston off the shelf but as i recall a .020 over weisco measures at the skirt more like 3.366. I could check as i have a brand new set of .020 over 6 bolt weisco pistons on the shelf to give you the exact width.

 

[miliman13]

.004 PTW the motor may slap for a few seconds on a cold day but then is fine. Larger then that they do tend to slap for longer but thats to be expected.


The looser we go the more blow by but that's the price to pay to be sure ring gap does not close and touch.

facts

 

[athlete3344]

Thank you so much for the feedback/knowledge Jed! I definitely need to do some homework but this is amazingly helpful. For what its worth, I live in FL and this will be a weekend/fun car.

 

[1990TSIAWDTALON]

Print one of these and record your work!
If I can find the PDF file, I'll post it so it's easier to print.
You can add in your info if you open them in "PAINT" or just write your info in.
Pops

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[jed344]

Print one of these and record your work!
If I can find the PDF file, I'll post it so it's easier to print.
You can add in your info if you open them in "PAINT" or just write your info in.
Pops

Adobe Acrobat

acrobat.adobe.com

Adobe Acrobat

acrobat.adobe.com

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I use essentially this same sheet to record everything. Very good idea.

I will also add just because there is more blow by that does not also mean the catch can fills up. We have found larger breather line's and good baffles in valve cover keeps the can quite empty. The spec's i use for a street full wet motor with correct breather set up will go a oil change and maybe have the catch can 1/4 full and its honestly just oily water that smells like e85. Mostly condensation inside the valve cover being sucked out i assume.

I had a motor we built 7+ years ago push a main seal out and soak a clutch disk. He then went to a appropriate sized breather configuration and the new main seal and the motor to this day is living a happy life at 550-600whp. Could be more honestly as it's on a PTE 6062 twin scroll set up now at 35-36psi .