Project 24

[murrayis]

83.5mm

[GTScotT]

OK, so here it is.

16 Thou top ring and 20 thou bottom ring would be considered 'spot on' for street application.

18 Thou top ring and 24 thou bottom will be for race application.

Your bottom ring should be 4-6 thou larger than your top. The two motors I built recently I went 18 thou for the top ring and then 22 and 24 thou for the second, the motor that I went 24 thou on the second is notably free'er than the one with a 22 thou bottom ring and also appears to have slightly better blow-by. However the motor with 18 and 22 is as much more aggressive in feel as the other is free'er, and happier to make power. The 2 thou difference in bottom ring accounts for 10psi static compression in comparable motors.

Most advice I received from machine shops told me to go 15 thou top and bottom, with the occasional shop telling me to go for a larger top ring. CP themselves recommended the 4-6 thou increase to the second ring and this was confirmed with ONE respectable shop.. I ended up following their advice and making the top ring a little larger than recommended, but following the 4-6 rule for the bottom.

In your case, and if I were building it for myself, I would happy go 18-22 again.

[murrayis]

Yea Ok, I have been told about 15 thou for NA + 4 thou for turbo + 2 for NOS

I've also hears of having the rings are different sizes with the top ring the larger.

[GTScotT]

Don't do the top larger. Its old V8 theory and I reckon you will end up with pathetic blow by issues

Having first hand experienced the difference of two motors with larger bottom rings I can tell you a little more gap on the bottom improved blow by. That engine has pathetic ventilation and zero blow by issues. Factory and in no need of repair it pushed oil passed the GT30's seals because of poor ventilation, same motor and turbo now faultless. Black magic.

Bore x 0.0045" is rule of thumb which will equal .00158", call it 16.. I think 18 is going to be better with your choice of 4 or 6 thou extra on the bottom.

[murrayis]

Ok finally everything has been machined, Washed and measured! Picked up the Ikea kit this morning!

Ikea Kit:

Block:

I just need to gap the rings down and it's ready to Assemble! Thanks to Mendham Engineering!

[murrayis]

So I spent today cleaning the block and replacing all the Welche plugs and giving the block a lick of paint.

I think it turned out ok!

[GTScotT]

is naaaais

i laaaaiik

[murrayis]

So whats everyonea thoughts on stud installation? Do you bottom them out or bottom them out and then back them off a turn?

[Ben C34]

I always thought they shouldn't be bottomed out.

[GTRPSI]

They are bottomed out "hand tight"

If entering a water jacket use ARP thread sealant.

Run a thread cutter through all bolt holes to clean threads before instalation.

About ring end gaps, follow the ring manufacturers instructions.

As an example JE Pro Seal recommend the following...

Street Moderate Turbo/Nitrous top ring .0050" per inch of bore, second ring .0055" per inch of bore.

Higher boost, say 20-25 psi top ring .0060" per inch of bore, second ring same.

Get into the 35+ PSI game and is .0070" per inch of bore, second ring the same.

Key pont is a little too much ring end gap is OK, to little will break your rings and score the bores.

On lower boost levels a larger second ring end gap is benaficial, the abilty to bleed off any gas that passes the first ring is important as its the pressure differatial that seals the top ring, opening the second ring a little more is the key.

On higher boost levels this is neglatable, however i tend to give the lower rings and extra .004" for guaranteed seal.

[GTScotT]

Bottom them out and hand tighten slightly with an Allen key. It's a confusing topic for sure.

I originally thought hand tighten was to wind them in by hand until they bottom out, but after many discussions I came to the above conclusion.

[Rolls]

With different piston expansion rates should you adjust those measurements eg if the piston is say a cast piston that barely expands or an old style forged piston that has poor expansion rate and moves a lot?

[GTRPSI]

ARP paper work is as i posted, you can drive them in with a allen key as most have a allen key head but leave the end pressue at hand tight, therefore dont lean into the allen key......just let them softly bottom out, hence hand tight.

Piston ring end gap and piston material expansion is 2 diffrent things.

Rings expand on their own in the bore, they float in the piston regardless of its expansion.

Point being the more heat, the more the rings will expand, so therefore the more boost/nitros/hp you run, the more ring end gap you need.

A good way to explain it is ring manufacturers supply their own ring end gaps regardless of what pisons you run, piston manufacturers supply a piston to bore clearance regardless of the rings you run.

Each have their own expansion rate and clearance depending on the material they are made out of and what your desired outcome is.

Follow the ring manufacturers and piston manufacturers instruction for clearances and running situation, most clearly explain NA, Boost, Nitrous etc clearances per inch of bore.

Edited December 28, 2013 by GTRPSI

[murrayis]

Just putting the crank in and it seems one of the studs may be defective and is 2-3mm longer than the other short studs.

Does anyone know where I could source single arp studs?

Edited December 28, 2013 by murrayis

[scotty nm35]

Are you sure you cleaned all the crap out of the hole? Make sure you do as GTRPSI mentioned and run a tap through the thread, then clean them out with carb cleaner, just to make sure there is no oil or crap in the hole or the stud will hydraulically lock before bottoming in the thread.

[murrayis]

Unfortunetly one of the studs is defective with the nut only able to be wound down 1/3 the way.

[murrayis]

Crank is all torqued down and ready for the rods and pistons in the next few days.

[murrayis]

Spent a very hot few hours yeaterday in the garage gapping the rings ready to be installed today however cannot find my ring compressor!

[GTRPSI]

What did you end up gapping the rings to?

What boost are you planning?

[murrayis]

18 / 22 second rings were out of the box 22 so couldn't go smaller

Boost 2.2bar ish