Targa Rotorua

Discussions relating to Turbochargers, Superchargers, Induction, Engine Mods, Exhaust Mods, and other items specifically to make your MX5 or Roadster put out more power.

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Euen
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Targa Rotorua

Post by Euen » Wed May 15, 2013 9:53 pm

Unfortunately my time on Targa Rotorua was cut short on Sunday morning by a little demon inside the engine tapping on the inside of the block.

Getting ready to pull the engine out but to cheer myself up I decided to hang my new Maxim Works header on the head to see how it fitted.

Pretty!
Attachments
Maxim1.jpg
TG Sports, classic roadster - modern technology. NA1800, 99 head, 11:1 +2mm Wiseco pistons, Link LEM, Alloy f/wheel, JR headers.

Furai
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Post by Furai » Wed May 15, 2013 10:59 pm

Dam they look nice!

MrGrey
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Post by MrGrey » Wed May 15, 2013 11:28 pm

Image

authentic
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Post by authentic » Thu May 16, 2013 8:16 am

Make sure to spray and wipe them down with brake cleaner and paper towels before first start up!

Kieran
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Post by Kieran » Thu May 16, 2013 1:52 pm

Why, if you don't and it gets stolen you can always tell its yours :lol:

SLYDIT
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Post by SLYDIT » Thu May 16, 2013 9:32 pm

wow i think this is the first engine long block failure ive ever heard of in NZ of a non mega boost turbo car. i wonder if its th famous #4 thrust bearing issue?
RED '90 TURBO.
SCARING PRIUS DRIVERS SINCE 2002

Euen
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Post by Euen » Thu May 16, 2013 9:47 pm

Nope. Took the head off tonight and it looks like something has got into No 3 cylinder. Small amount of damage to the chamber on 2 as well. There is still something embedded in the head on No 3 which is likely to be causing the tapping we could hear. The air filter is still intact so I can only assume something has dropped out of the inlet manifold. Will dig into that over the weekend to see what I can find.
Attachments
P5160248lo.jpg
No 3 combustion chamber
P5160252lo.jpg
Scratches on No.3 bore
TG Sports, classic roadster - modern technology. NA1800, 99 head, 11:1 +2mm Wiseco pistons, Link LEM, Alloy f/wheel, JR headers.

WideOpenThrottle
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Post by WideOpenThrottle » Fri May 17, 2013 8:05 am

That looks very much like what happened to mine at Puke! I had the same score marks down the cylinder walls too! Engine detonation from running too lean was suspected with my earlier turbo set-up!:D

Damage was to 3 & 4 cylinders which run the hottest and leanest from factory.
Attachments
engine detonation 001.JPG
engine detonation 003.JPG
1989 NA 1650
1998 NB 1800
2005 NC 2000
1990 Landcruiser
Surfboard
Push-bike
Hiking shoes

punkoutnz
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Post by punkoutnz » Fri May 17, 2013 10:37 am

Looks to me like a piece of ring has escaped and been thrashing around your cylinder. Or at a long shot, check something silly like your throttle body screw hasn't jumped out of place and ended up in the cylinder.
Cool sunroof bro...

WideOpenThrottle
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Post by WideOpenThrottle » Fri May 17, 2013 11:40 am

If you see tiny flaky bits and mini pit marks on the top of your piston then its been detonating i suspect.
1989 NA 1650
1998 NB 1800
2005 NC 2000
1990 Landcruiser
Surfboard
Push-bike
Hiking shoes

BRM
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Post by BRM » Fri May 17, 2013 6:01 pm

Was wondering where you were on Sunday, then saw you trailering our of Rotorua as we were coming in for end of day.

SLYDIT
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Post by SLYDIT » Fri May 17, 2013 9:46 pm

are those the exhaust valves broken? if it is i would bet that the combination of AFR and timing is causing your exhaust gas temps to be too high and weaken the valves. may pay to get a EGT probe on number 4 when you do your next tune.
RED '90 TURBO.
SCARING PRIUS DRIVERS SINCE 2002

REDBEN
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Post by REDBEN » Fri May 17, 2013 11:35 pm

When It comes to rebuilding the head purchase the Mazda GTR BG8R exhaust valves they are sodium filler and have a higher resistance to the heat and are a direct swap
1991 NA6 Mariner Blue with a twist of BP

Euen
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Post by Euen » Sat May 18, 2013 7:15 pm

Valves are all ok. The dark patch on one in the photo was just some oil on the valve. AFR is set to between 12 and 13:1 so shouldn't be an issue. Have stripped the inlet manifold and throttle body and no sign of missing parts. Throttle spindle/screws have been araldited to try and stop it falling apart although that is only usualy an isue on high boost which I don't have. No sign of detonation damage to the piston or rings fighting their way to the top. Will have a better idea once Glendene Engine Reconditioners have had a good look at it this week.
TG Sports, classic roadster - modern technology. NA1800, 99 head, 11:1 +2mm Wiseco pistons, Link LEM, Alloy f/wheel, JR headers.

harlansmart
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Post by harlansmart » Sat May 18, 2013 9:17 pm

Sorry to hear of the engine mishap but you will make it better than before!

Good idea this Ben, I just learned about that, always though they were solid before! - 2low2c showed me the other day in one of his Honda race engines valves that were special Honda racing ones filled with something like sodium for hot applications.
REDBEN wrote:When It comes to rebuilding the head purchase the Mazda GTR BG8R exhaust valves they are sodium filler and have a higher resistance to the heat and are a direct swap
Harlan

WTB: NZ New MX5

Black Darth Vader Turbo Miata

SLYDIT
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Post by SLYDIT » Sun May 19, 2013 6:27 pm

Mate I'm tellin ya your problem is exhaust gas temps. You can have afr within spec and still have sky high EGTs
RED '90 TURBO.
SCARING PRIUS DRIVERS SINCE 2002

Euen
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Post by Euen » Tue May 21, 2013 10:13 pm

Well, it wasn't exhaust gas temps or detonation. Seems that the a couple of valve guides had started to disintegrate. Not sure why, but they are cast iron ones and will be replaced with bronze ones. Engine was probably due for a refresh anyway. 5 years of competition takes its toll.
TG Sports, classic roadster - modern technology. NA1800, 99 head, 11:1 +2mm Wiseco pistons, Link LEM, Alloy f/wheel, JR headers.

SLYDIT
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Post by SLYDIT » Fri May 24, 2013 6:53 pm

Euen wrote:Well, it wasn't exhaust gas temps or detonation. Seems that the a couple of valve guides had started to disintegrate. Not sure why, but they are cast iron ones and will be replaced with bronze ones. Engine was probably due for a refresh anyway. 5 years of competition takes its toll.
because of EGT's.
RED '90 TURBO.
SCARING PRIUS DRIVERS SINCE 2002

Euen
I am quitting my job and going 5-ing
I am quitting my job and going 5-ing
Posts: 619
Joined: Tue May 23, 2006 9:42 am
Location: North Shore

Post by Euen » Mon Jan 06, 2014 10:36 pm

Well, engine is finally back where it belongs. Fired up without problem and sounds good.

5 years of Targa and other hard work had taken its toll and so it got a fairly comprehensive rebuild.

The pieces of valve guide (inlet side so unlikely to be EGT) had damaged the pistons badly enough that I had to go new pistons. 3 bent inlet valves, new valve seats, new bronze valve guides and new Supertech valve lifters. These are the shim under bucket type however because of a bit of a mix up with the supply, it was found that the shims were unnecessary and the buckets were machined to provide the correct cam clearance meaning that I now have one-piece lifters. This is becoming more common on a lot of newer engines.

Another problem we found was that the adjustable cam pulleys had started to crack. I have gone back to the standard ones for the time being.

Still have to reset the CAS timing and then get it tuned again.
Attachments
WP_000734lo.jpg
TG Sports, classic roadster - modern technology. NA1800, 99 head, 11:1 +2mm Wiseco pistons, Link LEM, Alloy f/wheel, JR headers.

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