14 replies to this topic

[svanh1993]

hey guys currently building my new motor for my satria old one finally let go with the high compression set up and 14 psi nearly lasted two years lol .un opened motor and a setup i fabricated my self .
now for the new engine build
1993 lancer gsr 4g93 dohc motor
goodies I have so far
4g93t complete motor no bolt one

brand new maxspeeding 800hp rated forged rods with ARP 2000 bolts. measures 133.5mm center to center and 21mm gudgeon pin hole
by working it out with this rods I'm hoping to go arias Honda b16 forged pistons I'm fairly confident it will work as they are 1mm lower from top to center of the gudgeon pin skirt may need to be trimmed ? gsr run a 19mm so is 1.5mm difference than the 21mm but may work as gsr pistons are taller
what did you guys have work with 21mm gudgeon pins and 133.5mm rod bighole center to gudgeon center ? my machine shop is willing to machine the tops if need be but hoping it will work out in the end ? hoping the valve cut outs may line up fine
new felpro 2 piece mls head gasket forgot the thickness
brand new seals for the head can seals the lot
sticking with the old turbo for now gt2871 was fun on 14psi and its efficiency is around 22psi so 20 will be a lot better for it
new 565cc injectors
and got some new ARP 3sgte head studs
I'm stuck on main studs and main bearings I hear acl restarted up the shop so will be available again from now .
are evo main studs the same that it may be a upgrade for stronger main studs ? chasing something like ARP or equivalent. want a strong bottom end as eventually will throw a gt30 in some cams and maybe 1000cc injectors and e85

upgrading a fwd gearbox to handle the power ATM its a standard satria gti box open diff f5m22 and will be needing stronger cvs
fuelpump will be a wwlbro gs450 455lph e85safe pump .what do you guys think ? also will be running a evo 6 ecu and patch loom for the new setup
pistons are my main concern and main studs
cheers alex

[doo doo]

So you bought the rods with the 21mm little end option? And you want a high comp motor?

Edited by doo doo, 14 October 2016 - 03:43 AM.

[svanh1993]

yes have the 21mm option but will be going a 8.5.1 to 9.5.1 compression with 20psi can wind more timing in then and even more when I go full e85 my old setup was high compression at 10.5.1 on 98 and 14 psi factory rods

[leadfoot]

the longer rod should help it rev but your in somewhat unchartered teritory i looked at longer rods with honda pistons but didn't end up going that path. also you can't use ANY advertised cr on the honda pistons as their combustion chamber size is probably different. for the record my cp pistons are a 10cc dish and are supposed to be same as stock gsr returning an 8.5:1 cr

 

[svanh1993]

yeah I understand with the combustion chamber volumes being different it will affect compression ratio just half wondering if it will stick past the block on these rods ?

[doo doo]

It looks lke there are 2 honda b16a pistons- one has a compression height of 29.9mm (PR3) and the other has a comp height of 30.7, or thereabouts. The 4g93 comp piston comp height is 30.8mm, so the second piston will fit without too much a problem with regards to piston deck height and desirable quench heights. Depending on what thickness of headgasket you use. The rods with the extra .5mm length over stock plus the extra .1mm in comp height means you might need to machine up to .6mm off the quench are of the piston. You won't really know exactly till you dummy assembly measure it all up anyway, if you get the block faced then there's that to be considered too.

 

I have some b16a honda pistons here (the ones with the 30.7 comp height) and I wouldn't recommend skimming them too much anyway- there doesn't seem to be a lot of meat under the top and you don't want to decrease the distance between the top of the top ring and the piston top too when turbocharging. Turbo pistons usually have enough there to remove a bit but the na pistons not as much.

 

You got a dome measurement in cc's for the honda piston and a dish measurement in cc's for the 4g93 piston to calculate your comp ratio? The dome fits no problem in the 4g63 head chamber, I don't have a 93 lying about to check but imagine it will be fine. Valve sizes look sinilar too- the valves fit in the pockets- but you might find the angles and placement are a bit different. Some fly cutting may be necessary......

Edited by doo doo, 14 October 2016 - 02:30 PM.

[svanh1993]

thanks mate you have been heaps of help on knowledge I have been talking to my engine builder a set of pistons I have in mind are arias forged Honda VTEC turbo pistons think they are a 8.9.1 can have a look later so my options seem like either skim .6mm off the piston or add it with a thicker head gasket maybe a custom one piece gasket may be the go as the one I purchased was the mivec one and I'm sure its only like .8mm or so its fairly thin

[doo doo]

Yep sorry I edited my post and doesn't make as much sense as i meant. If you use the pr3 honda piston with a comp height of 29.9mm and the .5mm extra length rods you won't need to machine the pistons, just headgasket thickness should suffice to get your desired quench height. Even a .8mm headgasket would get you a quench height of 1.1mm or so. Depends how high you want to rev it as to how much you want there. I wouldn't get a one piece custom head gasket done unless you plan on o-ringing the block.

The 30.7mm comp height honda pistons would need the skimming of the quench pads up to where the dome starts. If it's a turbo piston then there should be adequate top ring land area for a .6mm or so cut. The valves will be closer to the piston too- checking the valve to piston clearance on either setup will be pretty important anyway, as well as checking the piston flycuts match the valves adequately.

 

Edit- sorry, misinformation on the headgasket info- a 1.1mm head gasket would get you a .8mm quench for the unmachined 29.9mm comp height pistons using a .5mm longer rod, rather than the other way around.

Edited by doo doo, 15 October 2016 - 03:30 AM.

[svanh1993]

I'll have to get the measurements of this headgasket I have ATM is there a way I can measure it with the verniers perhaps ? or does it need to be fully compressed

[doo doo]

Most accurate is to measure it compressed, but if you can find an adequate sized flat section without raised sections for the verniers that'll give you an idea. 

 

Looking at piston options, something with specs like this- wiseco K542M815AP- which has a comp height of 29.85mm and a dish of -2.4 will give you a deck height of +0.1mm. Using a 1.3mm headgasket will get you a comp ratio of about 9.3:1 and a quench height of 1.2mm. Although with a faced deck and decked block that will change a little. You'll need to cc the combustion chambers and dummy assemble the pistons to check deck height before you'll know for sure what ,measurements you have. Then you could knock .1 or a bit more off the pistons to compensate if needed, or if you wanted to run a thinner headgasket. Thinner headgasket will bring the valves closer to the pistons also so it'd be worth dummy assembling the head and checking that too so you know what that looks like.

 

You could also go with something like this- wiseco K566M815AP- which has a dome volume of 5cc and a comp height of 30.1. If you machined the piston 0.3 or so to give zero deck height and use a 1.3 headgasket you'd have a comp ratio in the region of 10.1-10.5 depending on combustion chamber volume (10.1 for a 47cc chamber and 10.5 for a 49cc chamber). 

 

Just check the dish volume for the turbo vtec pistons as they'll drop the comp ratio by using a dished piston. 

[svanh1993]

I'll see if I can find a link of the ones I'm looking at

[svanh1993]

https://ariaspistons...ID10,7603241605

something like this perhaps

[doo doo]

Sure, the comp height is about 30mm so it'll stick out 0.25mm- 0.5mm with those rods depending on block deck height. As they're a flat top it'll be pretty easy to machine them down to 0 deck height or a bit lower.

 

What quench height do you intend to run?

 

0 deck and a 0.8mm headgasket should give you between 9.1:1 - 9.4:1 depending on how many cc's your head has, whereas 0.3mm negative deck height should give you 8.9:1- 9.2:1 with the same chamber cc variatons and gasket thickness, plus a safer quench height.

Edited by doo doo, 15 October 2016 - 12:46 PM.

[svanh1993]

head is stock casting ATM will have valves and springs redone over time but for now just the head with a light port work will be okay unless it really needs the stronger valve springs I think the headgasket is either a .6 or .8mm can't remember all I know is its a gti headgasket in mls which works for the gsr too

[doo doo]

The honda pistons will need to be skimmed regardless I think, so you really need to weigh up whether you want to pay extra for the machining or see what it costs to get some custom order cp's with the specs you need. Then your valve pockets, pin and comp height will be in spec straight out of the box. You could speak to Brad at Spool Imports about that as he should be able to organises that sort of thing and already sells CP 4g93 pistons.

 

What quench height do you want to run buddy? I ask it because if you want to run a .8 gasket and zero deck you're really pushing the limits to how small a quench to run, ideally you'd machine the piston down a bit more to increase the distance, but you're going to get the valves closer to the piston that way too.