Craigs New Datsun Sunny

2nd comp tester said noooooooo

pretty sure final plan is to build my spare block up with 87mm, or 88mm pistons if i have the balls, but make sure everythings 100% perfect clearance/spec wise with the help of a pro.

if it goes like this with 86mm and some fubarred rings, vtak and shit midrange map, 87mm built perfectly with proper vvl and 1 or 2 other goodies will be perfect for now.

big bore can wait a yr or 2
 
so your sending the block to me then :P

id just build another 86mm and put that in tear the old one down and see the damage.. dont bother paying for oversized pistons and shit for a 8mm overbore when you want to go 90 in the future its a waste.. build a normal comp 86 get it running abuse it and save for a big boy..
 
Was having a think Craig, did you check the following -

1. Piston protrusion to astablish the correct thickness head gasket required
2. Cylinder head and Block for warpage (were they skimed, if so by how much?)
3. Valve condition

All those could result in loss of compression.

Daniel
 
SuperDan said:
Was having a think Craig, did you check the following -

1. Piston protrusion to astablish the correct thickness head gasket required
2. Cylinder head and Block for warpage (were they skimed, if so by how much?)
3. Valve condition

All those could result in loss of compression.

Daniel
Click to expand...

1.5mm gasket was used which yielded even compression across the board for first few k miles til i noticed with this check

block and head were faced but only minimally to ensure flatness

valves were all cool too mate

its gotta be rings cos the compression readings went up to normal levels when the wet comp test was done, with the oil obviously sealing the little gaps in the rings. Anything else head/valve related wouldn't have shown up on the wet test so it's pretty certain to be rings.

Meh i'm not bothered, keep driving it, order some new parts - i'm tryna pluck the balls to go for 88mm on stock sleeves which a few people have done now, then some manley rods, new bearings. Be sweet.

just another monthly service for one of my frigging cars
 
Thats true yeah mate, guess it is looking like rings, if it was me i would get a new head gasket and some new rings ordered and just replace the rings, then see what happens
 
yeh i would but that means takin my engine out, dismantling it right down, gettin it honed again if the bores look ok, by which time it might be honed out a bit loose for the 86mm pistons. Also don't know if my pistons are ok to reuse anyway - by the time i've done all that, then ordered whatever i need new it'll be weeks down the line without a car that i need most days :(

Plus starting a fresh means i can get some forged rods which i shoulda done the first time, can get someone experienced to check specs n clearances with me, can maybe push it to 88mm for a few more horses and 2.1 - but most importantly have some peace of mind thats it all ok from the off.

I've never been totally satisfied cos the first 1-2k miles were on jez's road map, which lookin at my old graph was overfuelling, washing the bores and shit lol.

Fresh block, fresh build, fresh start. and i can do it while stil having use of the car :)
 
Raceworx said:
id be worried about it taking the head out if it went..
Click to expand...

Originally i said rape it, but after a few mins thought i said what you just said dude. Build a good but reliable bottom end and face the head when its all put together. Maybe drop the compression a tad to reduce the chance of knock a bit
 
Just a thought on the compression, would the increased compression result ina hotter burn or would it burn the same temperature as a stock engine?

Im just wondering about the ring gaps, hotter engine, bigger ring gaps needed?
 
true, but i set them to cp's suggested ring gaps for the 12.5:1 pistons so i'd hope that was accounted for.

although if it was knockin it'd be too hot i spose
 
next plan, nurse the car as it is atm, build up a spare block with 88mm pistons

then fingers crossed the old block is ok nick, bores etc and just needs a hone and some new rings, rebuild it with new rings and have it sit in the shed for when the 88mm one goes bang

:lol:
 
Quick question, how come everyone calls your car vtak, does VTEC switch both cams at same time and VVL does them independently, but yours is set to switch both at same time atm?
 
this weeks instalment....

clutch disc shat itself, suspected spring fuck up

no 88mm build now, no nothing. can't be arsed, lost interest pretty much

at best i'll re-ring my engine or buy another already built high comp bottom end and bolt it up nice n easy.

Granted in a few months i'll be eyeing up sleeve kits n stuff but for now i iz well pissed blaaaaaaad
 
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