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MG MGB GT V8 Factory Originals Technical - No!!!! Engine went bang . . . quite badly!

Ok, I have the WORST luck with cars! On my first official outing in my new MGB GTV8TT, I'd managed to go the whole of about 12 miles when the engine blew up, quite badly. Lots of smoke and shennanigans ending up with a possible timing issue diagnosis from Mr. AA. Not good at all.

I just hope that Mr. Valve didn't say anything to nasty to Mrs. Piston, as although I have a spare stripped engine I can't afford a full rebuild, never mind a new set of pistons, rings and valves!

Anyone any good with V8s?!? Help please!

Laters

Olly
OT Hayter

'lo OT,

Smoke sounds bad! Was it just from the exhaust or from elsewhere in the engine bay? Were you making boost when it went pop?

Hope you get it sorted easily,
--
Olly
Oliver Stephenson

Smoke was coming from the engine breather system :-/

Car was on boost when it happened, yes. The engine has a known ignition problem and suffers from pinking under high revs. I think I pushed it a bit too hard and it may have leaned out and put a few holes in some pistons, or maybe dropped a valve or two :-(
OT Hayter

Ouch! Sounds like a compression test might be in order....
Rob Edwards

Yus indeed, sounds like you'll now have some chunks of pistons missing and a collection of extra aluminium in the sump! Unlikely to be a dropped valve I would say, although you may have had an exhaust valve head snap/burn off. That's what caused this:

http://homepage.ntlworld.com/oliver.stephenson/piston1.jpg
http://homepage.ntlworld.com/oliver.stephenson/piston2.jpg
http://homepage.ntlworld.com/oliver.stephenson/piston3.jpg

Luckily this isn't from one of my engines - it's from a top fuel dragster :o)

What's your static compression ratio on the Rover?
--
Olly
Oliver Stephenson

sounds a likely diagnosis to me :(

Ooops

Let us know how you got on
Stuart Robson

It's going off to be compression tested on thursday. Does anyone know a good engine re-builder? I'd like to attemnt it myself, but I'm a little wary having never done anything like this before!

If I do need a rebuild I may as well go for fully lightened and balanced with some low compression Landy pistons . . . at least then I can crank up the boost without worrying too much!

bleedin' cars!
OT Hayter

I'd get on Ebay quickly and pick up one of RPi's recon short blocks... (probably work out cheaper)
Stuart Robson

http://www.djev8.com/
michel

I'm glad the AA turned up eventually Olly - sounds like it wasn't anything we could have attempted by the roadside. Lovely car, and I hope to see it running one day.

All the best

Nick (the 928 owner)
N Carrington

Hi Nick!

Yeah apparently it's quite fatal, but I'll have to wait for Thursday to be sure :-(

Many thanks for stopping, not many people would do that in a random tropical downpour!

I've heard about these recon short blocks from RPI, but to be honest I will need the engine lightening and balancing anyway, and I want a more meaty cam and I can't really use the standard pistons I don't think, so hopefully I can shoehorn in some 8.1:1 land rover pistons. Don't know if that'll work yet tho.

cheers

olly
OT Hayter

Well an RPI engine will probably be pretty well balanced, and there's not much point building a screamer with a wild cam when you have two turbos - the rover heads don't flow *that* well anyway, so best to make a strong engine that can make good torque up to the standard rev limit. I dare say that one could trust an RPI bottom end.

How much boost were you running before, and what is the control method? Oh, and what are the turbos?

Cheers,
--
Olly
Oliver Stephenson

Olly
Sorry to hear your bad news, you didn't say whether the engine actually went bang and came to an immediate stop, just went rough and was still running or went rough and then stopped.The first is obviously the worst case scenario and could mean a totally wrecked engine,either of the other two is likely to be valve or a combination of valve and piston problems and the crank and rods may be ok and you just need a set of 8-1 pistons and rebuild the heads. I don't think trying to do a compression test is going to be a lot of help, as a minimum i would be looking at having the heads off to see what the damage really is and then making relevent decisions dependent upon available funds. It would be helpful if you could describe more fully what actually happened and out of interest what fuel were you using.
Kevin
Kevin Jackson

>I don't think trying to do a compression test is going to be a lot of help

Well, if you've already got the gauge, the test is quick & free, and it will tell you which hole has the problem and which head to pull!
Rob Edwards

Rob
I would normally agree with you, but was thinking that as we do not know the extent of the internal damage that attempting to spin it over may do even more damage, and that was the reason I asked Olly to expand on the circumstances of the blow up. Lets hope it not to serious and can be repaired at reasonable cost.
Kevin.
Kevin Jackson

Sounds like a nightmare!!!!
Any news on the damage?
Mark

Hi guys,

sorry I've been busy with my new house.

Right, the diagnostic was fuel contamination! God knows how that happened, the car has 3 fuel filters. Cost £320 to sort out, but there is a bigger problem . . .

The car is breathing so heavily there is constant smoke out of the main breather all the time - Beech Hill reckoned a piston ring or two are on the way out. The guy who owned it before me did his own rebuild and I don't think he did a goos job, infact he's been a bit unresponsive to emails so I basically bought a bloody lemon.

Anyway, I need you advice on doing a rebuild. I've got a complete stripped 3.5 motor lying in the garage, plus the one in the car.

I want to stick with 3.5 litre, probably go with 8.1:1 pistons and get the spare block honed etc. to +20 thou to ease things up a bit. I'm probably going to get someone like V8 Developments to lighten and balance everything (not too expensive) and Stage III heads with a slightly better cam and upgraded lifters. But since I'm skint that'll be after xmas.

In the meantime I just want to sort it to get it going - what's the best, quickest and cheapest thing to do?
OT Hayter

My short list of cheap to fix sources of oil post turbocharger conversion:

A turbocharged car needs a PCV valve designed for a turbo charged engine. A turbo WILL blow oil through a PCV intended for a normally apspirated engine. Also, the oil feed to the center section of the turbo should have a flow restrictor otherwise the oil pressure will push past the center section seals and you will burn ingest and otherwise consume oil.

Regarding cam selection, a stock cam is a good choice for a turbo engine. Backpressure in the exhaust manifold caused by the turbine will result in reversion of exhaust gasses into the combustion chamber with a "hot" cam due to overlap, same for the fuel charge on intake with the boost pushing it out the exhaust side. Excessive overlap common in hot cams is not a good idea for a turbo engine.

Turbo engines go kaboom for a variety of reasons. Most commonly:

too little fuel on boost;
too much spark advance on boost;
too much boost pressure;
too hot an intake charge;
insufficient cooling.

Is it carbed or fuel injected? Factory or aftermarket ECU? If factory ECU for a normally aspirated engine, then you probably have (or should have) some piggyback workarounds to correct fuelling (Hi pressure pump and an Adjustable Fuel Pressure Regulator) and pull spark timing on boost - like an MSD Box. Also a J&S Knock sensor & box would be a good idea. If using an aftermarket ECU, simply use oversized injectors and remap your fuel and timing curves.


Instruments are a good idea with a turbo install, particularly with an aftermarket or custom one. I'd want:

Boost guage (maybe with a max boostlevel memory)
02 guage (wideband for tuning);
EGT guage (another tuning aid and an early warning of impending doom);

Does the system include Intercoolers; wastegate control; Blow-Off valve; oil squirters on the underside of the pistons; forged pistons?

I'd want to know what was done to tune this sucker once it was installed. If that info was unavailable or unreliable, you should not go on boost without a wideband O2 sensor in the header.

Regards,

Brian C.
Brian Corrigan

This thread was discussed between 03/10/2005 and 21/10/2005

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