recurring race engine problem help


D

dave benson

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Jul 24, 2008
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Hi, below are some pictures of my B16A2 civic engine which as you can see on the pictures has been picking up on the piston/bores for some reason. This is the second time this has happened, the first time it was blamed on a missing oilway plug in the head after its original build, but this time after a rebuild there is no obvious reason.
The engine has covered around 400 competitive miles gaining three class wins with no problems, oil pressure is great and still is, got hot once on the start of the North West Stages, went into safe mode for one mile but didn't boil or lose any coolant, in fact the standard gauge didnt go into the red, the capillary one said 115 degrees
Brief spec is standard block/crank/oil pump, steel rods, JE forged pistons, 11.5 cr, ACL bearings, ported/modified head, vtec removed, toda cams, jenvy throttle bodies with cold air feed and pipercross 600 airbox and filter, omex 500 ecu, mapped on rolling road, tony law manifold and 18 row mocal oil cooler, using Valvoline racing 20/50 mineral oil.
It's been great but at Weeton a few weeks ago it started to blow blue smoke from the exhaust on the start of the later stages, was fine on the stages and still managed 7th OA, but it was obvious a problem was brewing.

All four pistons/bores are the same, with wear on both thrust faces

Thoughts anyone ?
 

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Who built the engine ? Is it the same spec and damage as previous failure ?

Any datalogs ?
 
i built it, piston clearances were set at the JE spec of 2.5 thou

the problem is the same as previously

no datalogs
 
Ok. Without sounding too general it does look like the pistons got too hot in there , whether that was due to a bad map or fuel delivery is hard to tell .
 
despite all the pistons/bores showing the same damage, only one has a black plug/combustion chamber( the one burning oil !), the other three plugs are a nice pale brown colour.

if it was bore washing would the plugs be brown ?

could it be the cold start ?

or could it be doing it when on the rev limiter i,e spark cut but still getting fuel , which happens quite a bit !!!
 
Be surprising to get bore wash second time around , was that not taken into account building/mapping the second time ?
 
If you were experiencing bore wash your plugs would be black, what were your ring gaps? Has the bore been checked for ovality?
 
it was only mapped the once, the original problem was put down to the lack of oil pressure when i first tried to start it due to a brass factory fitted oilway plug that was missing(not taken out by me)

its not been checked / measured yet, its at the machine shop waiting

ring gaps were set as per JE piston spec sheet, can't remember as it was a year and a half ago

i'm thinking the cold start may be too aggresive and then its fine once warm as the plug colour is not too bad ?

or when its on the limiter, probably a couple of times per mile

it's took 400 miles at between 5000-8500 revs continuously to happen
 
Same block as the first failure? Have you checked the cylinders for ovalness? Oil squirters all free and clear?

Have you always used 20w50 oil?
 
As said somewhere above that has got very hot and ran lean, I have pulled apart a few engines with the same symptoms, what do the piston crowns look like?
 
rs250nut said:
As said somewhere above that has got very hot and ran lean, I have pulled apart a few engines with the same symptoms, what do the piston crowns look like?
Click to expand...

the block was a different one, i will be using another one next time

piston crowns are fine, just a small amount of carbon

rings are not blue or burnt, the top one is very sharp and has lots of minute chips out of it, which you can only see with a magnifier

the oil i have always used is valvoline racing 20/50 as that is what i used in my old car(205 with a samba engine) as it ran the same oil in the engine and gearbox and stood up to the heat well, maybe this was an error and the oil isn't good enough or to thick ??

planning on swapping to silkolene pro s 5/40 ?????? or 15/50 ?????
 
10w50 or 60!

are the piston 81mm? might be worth going 81.5mm to get a nice new square bore!
 
So I rebuilt the engine but didn't change the ARP con rod bolts and after 40 miles whilst leading the 1600 class it threw a rod at about 7000 revs

Doh !

So I rebuilt it again with wiseco pistons this time, new rods / bore / shells etc
Took it to get the map leaned off to eliminate bore wash, did 100 miles to run it in, did a small event and after 50 miles the bore scratches have started again on the thrust faces !

The air filter was brand new and oiled, now running silkolene 15/50 pro race and I was trying my hardest to change gear at 8000 revs with the limiter set at 8400, temperature on stage never went above 90 degrees

What is going on !?
 
Are u running oil squirters?

If it were a lean tune, you'd have scoring above the top compression ring.

What's the scoring on the bore like?
 
import_trung said:
Are u running oil squirters?

If it were a lean tune, you'd have scoring above the top compression ring.

What's the scoring on the bore like?
Click to expand...

Here's some pics of the marks after 100 road miles plus 50 stage miles

I am running oil squirters and the clearances / ring gaps were set buy the engine builder to the specs on the wiseco spec sheet
 

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Another pic, I know it's not bad at the moment but it shouldn't really be doing it at all !
 

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are those arp head studs? there is a very well know honda engine builder in ireland who won't use arp studs and nuts for the head or the crank as he has found they distort the blocks.

was the block bored from 81mm? was a torque plate used with those studs if so?
 
Eoghain said:
are those arp head studs? there is a very well know honda engine builder in ireland who won't use arp studs and nuts for the head or the crank as he has found they distort the blocks.

was the block bored from 81mm? was a torque plate used with those studs if so?
Click to expand...

im not saying your wrong but what about all the fellas running turbos alot just uprate the headstuds with no problem.
 
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