[Supras] #5 cylinder damage, bhg

[berniek at technicaldevelop.com]

PS:  Also moved the oil pickup back to the rear kickup in the pan.  Had to
remove most of the rear baffle to do it.


Bernie


> Fred:
>
> Sounds as if you had foreign material enter the cylinder.  I'm somewhat
> concerned about the HKS air filter I'm using because the foam pores are so
> large.  I had a '90T I was going to upgrade after having it since '92, but
> rust here in the northeast, and the fact that it had 156K miles on the
> clock discouraged me.  It was starting to need upholstery work as well.
> Then it had a BHG (original gasket, with 72 lb-ft torque.
>
> To make a long story short, I sold it as-was, and got a '91T from Houston,
> no rust and 103K miles.  Seemed to run well, but was low on power.  I
> figured I'd get the jump on a BHG by installing a Cometic, lapping the
> block with a circular lapping plate driven by a small gearhead motor.
> After getting the head off it was obvious that it already had suffered a
> BHG and was repaired.  But #1 cylinder was scored, and the piston did not
> come up to the deck, so it may have hydrolocked during the BHG and bent
> the connecting rod.
>
> By that time I had already started to freshen a JDM engine I got.  I
> reused the stock bearings as they were fine.  No bearings had any wear,
> including the thrust sections (it came from an automatic, but mine is a 5
> speed).  I reused the stock pistons thinking I never had any reason to go
> above 15 PSI boost.  Well, now that is 17, but I don't dare go higher.  I
> did consider forged pistons, but Weisco due to the longer skirt for less
> rocking and the fact that like stock pistons, the wrist pin is offset
> 1/16" toward the thrust side to keep it a little quiet.  That is not true
> of JE pistons.  I also have a 57 trim CT26, but with the wastegate passage
> bored out and no turbine clipping.  Mine was also done by Performance
> Techniques.
>
> Did the head myself also, as the valves just required lapping (took the
> head and block to be surfaced at a shop, though).  Also refinished the cam
> journal caps for correct clearance (they always wear, especially on the
> last exhaust side).  Made valve spring shims from bored out washers, and
> set clearance using shims and buckets salvaged from scrap heads on ebay
> (they were cheap, but heavy to ship) and some surface grinding of shims.
> The engine went togther well, with the Cometic gasket, ARP studs, 550cc
> injectors, Lex, Walbro, '98 mounts (very strong).  Now also have a
> recirculated Raptor BOV, Treadstone IC (like Spearco), homemade 2-1/4"
> hardpipes.  Engine does have piston slap until the thermostat opens,
> expected.  Also have 3"  Random Tech and HKS exhaust pieces.
>
> Man, lunchtime is over.  Gotta get back to work.  Let me know if you need
> anything additional I can help with.
>
>
> BernieK
>
>
>
>> There was scoring on the exhaust side of # 5 piston skirt and cyl wall,
>> the
>> oil ring and # 2 ring were kind of stuck just above the scoring. Not
>> sure
>> if
>> it was caused by the scoring or that caused the scoring. This motor
>> always
>> had kind of a piston slap odd noise when held about 2000-2200 rpm  in
>> neutral.
>> But it drove out fine for 60k miles with the noise, I got the car with
>> 94k
>> on it years ago.  Cylinder didn't hydro lock, just kept losing coolant
>> after
>> the last hard 16psi run on the stock head gasket.
>>
>> What bearings did you use when you rebuilt yours, I have used cleveite
>> 77
>> many times in small and big block chevys but this is my first time going
>> thru a 7M. I am now considering forged pistons, if I can find a good
>> deal
>> on
>> them . Jims post makes sense.
>>
>> I like the performance techniques turbo, I had my CT26 done 7/06, 57
>> trim,
>> no clip, bored out inlet housing.
>> Any suggestion would be appreciated
>>
>> Fred
>>
>>
>>
>> ----- Original Message -----
>> From: <berniek at technicaldevelop.com>
>> To: <fbnetrazor at hotmail.com>; <supras-request at supras.com>
>> Sent: Tuesday, February 12, 2008 4:46 PM
>> Subject: Re: #5 cylinder damage, bhg
>>
>>
>>> Just curious as to what happened.  Did the cylinder hydraulically lock
>>> from coolant due to the BHG?  Or was the damage there before the BHG
>>> from
>>> running too much boost with stock pistons?
>>>
>>>
>>> BernieK
>>>
>>
>>
>
>