Ring gap help !!

[ChiTownJDM]

Okay , so this is my first time gapping rings and I need a little help!

Piston - CP 87mm 8:5:1 comp
rods - BC rods

So , cp recomends on the sheet .0035 gap on the rings. But I am turbo, so doesn't this mean I need to open them up more? . I was reading and saw online

Sport compact turbo/notrious 450+

Oil rings - .015 - .050
Top Ring - .0050 - .0055
Bott ring - .0055 - .0060

Those are the gaps I should use? What's this inch per bore I keep reading about ? Cause I'm 87mm not 86mm so +1mm bore.

[hanzbrady]

Follow CP's sheet, they know what they're doing. Those ring gaps you listed are massive so unless you're building a race only engine that you're expecting to get super hot I wouldn't use those.

I personally did something along the lines of

.022 top
.024 bottom

on my personal car.

[ChiTownJDM]

Follow CP's sheet, they know what they're doing. Those ring gaps you listed are massive so unless you're building a race only engine that you're expecting to get super hot I wouldn't use those.

I personally did something along the lines of

.022 top
.024 bottom

on my personal car.


What kinda power? My motor is fully built,. Building the car for drifting up the motor is over kill.

[hanzbrady]

What kinda power? My motor is fully built,. Building the car for drifting up the motor is over kill.

My motor is set up for about 500hp, but even on Dave Briggs's SR we never got into the .030's as far as ring gap is concerned. The gaps you listed is along the lines of1000hp alcohol no coolant drag engine builds.

[KAT-PWR]

My engine that's been in car boosted for 30k miles has .018, .020.
300-400whp forever 5% leak down

My high horse power spare I believe is .02, .022 (600hp goal)

[bardabe]

CP reccomends the following.

"SPORT COMPACT: Turbo/Nitrous applications to 450 - 750hp

Top Ring = .0050 - .0055
Second Ring = .0055 - .0060
Oil Ring – Actual Gap = .015 - .050"

these measurements are per inch, so to determine your ring end gap you'll have to take a dial bore gauge. measure the exact bore of each of your cylinders and then multiply by said number. so a close example would be

86mm = 3.3858"

3.3858 x 0.0050 = 0.0169" of piston ring end gap on the tight side or
3.3858 x 0.0055 = 0.0186" of piston ring gap on the loose side.

everyone has their own preference of ring end gap, I just wanted to clear that up for you so that you don't run a massive gap and ruin your build.

[ChiTownJDM]

You guys rock !! Thank you! I ended up doing
.018 Top ring,
.023 Bottom ring .
.015 oil rings.

Thank y'all for being so helpful!!!

[jedi03]

I followed cp numbers to the t...no issues on daily driven vehicle!