HELP! Blew headgasket on dyno night before event!

Robert Venable · Post by **Robert Venable** » Mon Oct 16, 2006 5:29 pm

mattmartindrift wrote:White exhaust valves are heat, clean metal is water, steam cleaning rarely leaves that sort of color. It leaves nice clean metal since all of the water is flash evaporated.

I don't see how this is possibly, more heat normaly means more power. How would you produce more heat and more power from a combustion chamber that was not sealing well? And about the water, cleaning the metal you are right, with water injection. But he had coolant in his combustion chamber, not pure water or a mixture of alchol or methonal.

Bill Hincher · Post by **Bill Hincher** » Mon Oct 16, 2006 5:39 pm

extra water in the combustion chamber increases the compression because it takes up space, we used to see 6/71 GMC desiels run like a raped ape but have a headgasket blown, same thing with piston engine aircraft, when they needed an extra boost at altitude the would squirt water into the cylinder, later they used nitrous ,thats where Smokey Yunnick found out about Nitrous........flying B-17s over Europe

Bill Hincher · Post by **Bill Hincher** » Mon Oct 16, 2006 10:26 pm

All your points are well done >;o) and well thought out Matt.

Bill Hincher · Post by **Bill Hincher** » Tue Oct 17, 2006 7:53 am

from what I can read, the heat in the piston has to be delt with differently in turbo boost engines

this is from the book ' supercharged' by Corky bell

two ways of controling heat are viable, ceramic coating the piston top and oil squirting the bottom of the piston on the exhaust side.

Also the piston ring lands should be much wider then naturaly asperated engines

oil squirting is preffered . I wonder if a main bearing could be tapped and a spray system could be built.

On two stroke engines, we used to drill two small holes on each side of the exhaust port , in the piston skirt, below the lower ring to allow oil to spash up into the cylinder wall under the exhaust port, but in a two stroke the crankcase is under pressure and the 4 stroke is not

Bill Hincher · Post by **Bill Hincher** » Tue Oct 17, 2006 9:41 am

what kind of exhaust temps was he running at the hedder? its directly related to A/F ratio
Judging by his pictures, his turbo is closest to #1 cyl, the initial hedder length carries away most of the heat, that hedder may be the shortest to the collector
Injecter sizing could just be desguising the problem by dumping in extra gas and making it run cooler

Donno for sure, but the gasket blew OUT so you know it either has too much compression/boost or it cant get rid of the spent gasses fast enough and it backed up

Bill Hincher · Post by **Bill Hincher** » Tue Oct 17, 2006 10:28 am

well....the proof is always in the pudding >;o)

I guess its a matter of information. I like it when the guys with the most money dont win, the guy that makes the best choices does.
you seem to be very well informed, maybe the next dyno run will go well

Bill Hincher · Post by **Bill Hincher** » Tue Oct 17, 2006 2:30 pm

all I said was

what kind of exhaust temps was he running at the hedder? its directly related to A/F ratio

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mattmartindrift
Posted: Tue Oct 17, 2006 8:54 am

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And you're very very very wrong about EGTs EGTs are not directly related to anything, they're dependant upon AFR, and TIMING MOSTLY!!!!!
I'm just not understanding a lot of your rationale

Post by **DJpowerHaus** » Wed Oct 18, 2006 11:27 am

Message from Kevin finally:

quick reply so you know, when I blew up my VR6 the bad cylinder was washed clean just like your valves. I'd say it was from the coolant.

next time we run the car, we could read the fresh plugs to look for det and add fuel if necessary, no problem.

Bill Hincher · Post by **Bill Hincher** » Wed Oct 18, 2006 11:49 am

I agree with Matt about the timing controling the heat, the assumption here is, that all cylinders are doing equal work, but they are not. each one of your cylinders are complete seperate units connected by a crankshaft. The ECU is ' supposed ' to be grouped, but you cant tell. the ignition coil is signaled from the ECU and the injecter duty cycle is controled by the ECU ' individually' the only way to tell if the ignition signal is working properly is to degree the harmonic balancer ( after its checked for index) to all 4 cylinders and testing ignition advance control at all RMP ranges on each cylinder individually, same thing with the duty cycle to the injecters, they have to be checked one at a time, after the duty cycle is verified, then you can ' balance' your injecters to tune the engine , taylor made to its needs

Post by **DJpowerHaus** » Wed Oct 18, 2006 12:57 pm

My ECU does have the ability to trim fuel differently on each cylinder so I might try to fine tune it in the future. I'd be working off of comparing spark plugs though.

Bill Hincher · Post by **Bill Hincher** » Wed Oct 18, 2006 5:59 pm

I am not quite sure but I think it sequential up to 2500 RPM and then it switchs to batch, at least that is how the ones I have worked are, that way they fire twice over 2500 Rpm
The useful life of a transister is 10 years, there should be 4 individual drivers ( transisters) driving the injecters and 4 individual switchs (drivers) signaling the coil to fire ,
each transister is going to be slightly different and that driver could case major preignition is it is ' leaking'

Bill Hincher · Post by **Bill Hincher** » Wed Oct 18, 2006 9:52 pm

Check this site out, this guy has got it figured out pretty good, I know its about a stealth, but it is aslo how a Mits should be set up

http://www.stealth316.com/2-fuelinjection.htm

Robert Venable · Post by **Robert Venable** » Thu Oct 19, 2006 9:36 pm

What computer are you using??

Robert Venable · Post by **Robert Venable** » Fri Oct 20, 2006 1:40 am

Which do you preffer and why??

Post by **DJpowerHaus** » Tue Oct 24, 2006 11:16 pm

Autronics interface isnt easy for me to use, but when Kevin was using it.. wow. Its designed to NEVER require a mouse. A good operator like Kevin can zip around with the keyboard faster than anyone swtiching between a keyboard and mouse.

And my ECU has 4D tuning.. not sure what all of them are, but that's how it was described on the Autronic board before. I think later models when higher than that with maps for throttle position, temp, load, exhaust backpressure, etc etc.

Post by **DJpowerHaus** » Wed Oct 25, 2006 4:34 pm

Here is some info about the tune:

Target A/F Ratios:

Ignition Timing Map:

and for the curious this is how my engine is setup in the software: