Compression vs head gasket type

trikesrule · 17 Dec 2006, 10:19 (Ref:1792606)

One of our engines (inline six) runs 13.4 to one. Been using composite head gasket with steel rings (standard type) and blowing them regularly since the onset of unleaded fuel. Thinking about moving up to MLS with a glue/sealant. What are your thoughts........trikes

Notso Swift · 18 Dec 2006, 00:31 (Ref:1793184)

Well, my turbo car runs 9.3 plus 17 psi of boost on a standard head gasket, are you sure they are blowing from pressure? My effective ratio is the same (little higher) as yours, I run on Caltex 98, straight from the pump, no addittives. So I personally doubt it. More likely mild detonation. Re-tune it. Try and fit a knock sensor if it doesnt already have one to take out 1-2 deg of advance when you need tol.

EDIT Just remembered, you are in Tassie so you cant get really fresh fuel. Without getting those dedicated motorsport fuels you may be in trouble. Your 98 octane may be really 97, while for me it may be reall closer to 100 (which I have heard is the corrcect figure for most of the 98's)

trikesrule · 18 Dec 2006, 08:46 (Ref:1793327)

Hi notso Swift I've a feeling that fuel quality and the lack of a good ignition system may have all attributed to our head gasket problem. I've got many things to ponder. Yours and the other guys suggestions are great food for thought. This is my first full time season with this three car team and there is much to do. A fuel dude friend of mine tested all the Premium fuels after one decant and two decants. The results were astonishing. So what I read from u guys I combine that with what I've been shown recently and see if I can make more usable hp. What heat range plugs do u run? We're running SplitFire c which I'm told by Lynx is one heat range colder than std. Some where along the road I've forgotten the KISS principle...........trikes

knighty · 18 Dec 2006, 13:17 (Ref:1793509)

I cant comment on your fuel grade and ignition systems - but if you are searching for the ultimate sealing solution, here are some considerations for you

1) you might be lucky to find an MLS gasket that fits - but if you need to commission a custom run - forget it - the tooling costs millions

2) for high pressure and high temperature cylinder applications your best bet will be a wills ring - people dont understand these and are quick to dismiss them - the theory of operation is just so simple - in short - the higher the cylinder pressuer - there better it will seal........check out this link

http://www.busakshamban.us/busak.sha...nds.htm?wlb=13

the type you need are not gas filled but actually feature holes that will face the combustion flame, from memory I think the type you need is made from Inconel, obviously you will need to get the block machined accordingly - the compression will rise as you will not have the gasket thickness - so you could bring it back down by dishing the piston crowns a little.

ian_w · 18 Dec 2006, 17:08 (Ref:1793781)

The question is, why are you blowing head gaskets? It sounds like it may be due to detonation if its occured with a change in fuel type. Even if you fit a bullet proof head gasket the engine will still eventually be damaged by the detonation - erosion of the piston crown and combustion chamber. You really need to stop the detonation by either retarding the spark a little, lowering the CR, running the engine cooler, running a bit richer or finding some better fuel.

trikesrule · 18 Dec 2006, 20:44 (Ref:1794012)

A super efficient seal is a must I feel. I strongly suspect when our engine man fitted the head studs (his first time) he didn't cycle them correctly. See our team knew that unleaded fuels were coming in this season so as soon as we heard this we changed straight over to BP Ultimate (last season) and played with Octane Boosters. No head dramas at all last season. The only thing changed was the head studs. Now we've also improved the ignition - it's a nice big fat blue spark which doesn't degenerate into a orange spark with any part of the system. On the dyno we advance the dizzy until we start to get power drop off then retard two degrees and it should all be in by 4000 rpm. We can get MLS Gaskets for our engines but the guy at the shop say's to use a std composite with Hylomar. He reckons we don't run enough compression to warrant MLS. What are your thoughts guys? ........trikes

Notso Swift · 18 Dec 2006, 22:00 (Ref:1794073)

I am with IanW and still stick by my advice, DETONATION IS EVIL

ian_w · 19 Dec 2006, 19:30 (Ref:1795025)

It sounds like your ignition setting on the dyno may be a contributing factor. When you are close to optimum spark advance the change in torque with spk adv is very small so by the time you have seen the torque drop you are probably quite a bit over advanced and coming back 2 deg may not be enough. In fact it is also possible that the engine is damaged during your ignition setting procedure as you have over advanced it too much.

Your best plan is too run at a steady speed and take logs of torque as you advance the spark - this is much easier if you are on a engine dyno rather than a chassis rolls. Next, plot the results and with a bit of luck you should have a decent trend where you can pick off the spark adv that gives you maximum torque ( MBT in 'engineer' speak ). You should hopefully see from the data the curve is pretty flat, you don't necessarily want to pick the absolute maximum torque point but maybe a degree or two retarded from this and trade-off a few tenths of a percent performance drop for a significant reduction in cylinder pressures as well as extra detonation clearance.

Not running at the absolute maximum torque point may sound a bit counter intuative but I work on engines used in major International championships and this is how we map them. The lower cyl pressures gives everything just a little bit of an easier time, e.g. pistons, rods, bearings, cranks etc and the performance loss is bearly measurable.

Are there any other signs of detonation on the engine - lack of carbon on the edges of the head and pistons and general surface pitting?

You have also been talking about 'cycling' your head studs, I must admit that I've never heard of this and its not something we do at work. When you switched to the ARP studs, did you get a torque figure to use with them? Also, did you use plenty of anti scuff paste on the threads and underneath the head of the nut? If not, you may have had too much friction and not generated the necessary clamping load. With your composite gasket do you normally retorque after a few miles and was this done properly?

From my experience multilayer steel gaskets are the way ahead and would use them given the choice every time. Perhaps a change to this type of gasket and looking at some of the areas I have suggest may fix your problem.

I suppose the other obvious question is are both your head and block flat? Its not uncommon for the area around the head stubs/bolts to 'pull up' slightly over time, this means that when you clamp down your new head gasket you may not be getting the correct pressure on the sealing ring. I'd think about giving the block a very light skim.

trikesrule · 19 Dec 2006, 20:31 (Ref:1795081)

Thanks guys. You've been most helpful. It's time to make some decisions. We're racing new years eve. Will let u know how it goes.......trikes

trikesrule · 2 Jan 2007, 10:35 (Ref:1803283)

Hey guys Disaster on Saturday night again. The engine guy had the car for two weeks. I couldn't have the car until 1.30 Saturday arvo (race day) so it went out on the track not dyno tested. In Heat 1 it went like a scalded cat for three laps then the fluttery miss where it fouls the front plug returned. Finished third and slowing. Threw another plug at it. The rest looked a little rich. Heat 2 the same. Threw another plug into the same pot. Other plugs were slightly rich. Heat 3 the same until lap 3 then it blew the composite gasket out the side of #2 along the metal. The engine man and the owner came in the pits after the meeting where they copped a serve from me. Our run for the Championship looks a little slim now. But every cloud........ I've left them to sort it out.....trikes

trikesrule · 2 Jan 2007, 11:05 (Ref:1803308)

Saturday night three cars blew head gaskets. Things in common are 1 All the same engine brand. 2 All use the same fuel - BP Ultimate. 3 All use Octane boosters. We use Nulon Pro-Strength (13.4:1) so does 13.7 guy. Unsure about 12.1 guy type. 4 13.4 and 13.7 have the same engine builder. 5 All three heads came out of the same shop (where the engine builder just happens to work). 6 13.4 and 13.7 use electronic ignition 12:1 uses Points. 7 All have their Advance in by 4000rpm 8 degrees initial. 8 Ours is the only one with a steady timing mark. The other two jump around (wear in the dizzy?). 9 All blew between #1 and #2 along the metal to air and they all had evidence that between #5 and #6 was going too. But Wait Theres More........trikes

trikesrule · 2 Jan 2007, 12:14 (Ref:1803370)

Sunday 12:1 brings his car to my place, hands me a wad and say's 'fix it'. Whipped the head off. This is what I found. Gasket blown as above. Debri from old gaskets on the deck (with rust forming under these!). Apart from melted areas this gasket came off intact. Inlet/exhaust on the same side with these engines. Manifold gasket put on upside down. Mixture had a 3mm hurdle to jump (on the floor). Medium detonation on exhast side of #1 and #6. Tapped bolt holes, lots of crud in most. For the repairs I'll do what the majority say's. Today, had head checked for flatness - 3 thou warp. Chamber cc' at 44. C/R 11.9:1. Let the decisions come cause the clocks ticking. Racing in two Saturdays. New engine shop recommended a graphite head gasket. Anyone used one of these? The composite manifold gasket was about to blow between 5 and 6. Plugs are std heat range.......trikes PS I've got nothing to say about helping the opposition. Ian and Notsoswift I'm listening and I've got the reins now.

ian_w · 2 Jan 2007, 18:57 (Ref:1803876)

Sorry if I'm a bit slow but can you explain exactly where the gasket has failed - is it between cylinders or to the outside of the engine. Standing at the flywheel end of the engine and zero degrees being at the front, counting clockwise at what angle is the failure. Where is the failure relative to the inlet valve, exh valve and spark plug? What do the pistons look like? If you have some photos them send me a PM and I'll give you my e-mail address so I can have a look.

I've never heard of a graphite head gasket, do you have any more details or a manufacturers name. Other choices could be a solid copper gasket or Wills rings as somebody else suggested. However, before going to these levels it still sounds to me like you have a fundamental problem somewhere that needs fixing rather than just keep beefing up the head gasket.

You said the head was 3thou out, this doesn't sound great to me I would be tempted to have it skimmed. Have you checked the block as well, as I said before I'd also give this a light skim as it is quite common to get high spots around the head bolts that result in much lower head gasket loads than required.

How are you setting your fuelling mixture, hopefully with a Lambda meter or CO meter. You say the plugs look rich and are fouling - this sounds to me like you have the wrong heat range spark plugs. I would try one grade hotter ( lower number in NGK terms ). If you have just been setting fuelling on plug colour you could be miles out.

I set my engine up on the dyno with a lambda meter and it all ran fine. However when racing it would develop a slight misfire after a few laps and the plugs were a filthy black colour. Swapping from an NGK 8 to an NGK 7 grade fixed the misfire and the plugs looked a 'normal' colour as well. In my experience most people fit plugs that are too 'cold' - in fact for my engine most people thought an NGK 8 has too 'hot' and were recommending a grade 9!

trikesrule · 2 Jan 2007, 20:12 (Ref:1804215)

Ian reread the above for me you will find most ofthose answers already there Thanks. Remember I'm working on 12.1' car and not the team I work for. I seem to be out of the loop with what goes on with the usual team car. So lets forget about that one at the moment. As I said 12.1' car is at my place. So I'm starting from scratch with this one. The fuel mix will be set up with a sniffer up the exhaust but we're getting ahead of ourselves. Lets back track to diagnosing the problem. Last night I cleaned up the deck. Smoothed tops of the #1 and #6 pistons with a fine stone. Bottom tapped all the threads. The pistons 1 and 6 have pitting covering 1/3 of pistons surface headed toward left side (farthest from manifold) and 1/3 toward the exhaust. Gasket had melted and blown out ring and broken gasket along the ridge between 1 and 2. 6 was going the same way. I feel the upside down manifold gasket heavily attributed to 1 and 6 lean conditon but also suspect a combination of undiscovered sequences. I'll have a look at a Graphite gasket this morning. I can get MLS gasket no problems. Not taking any more off of head (re 3 thou out). Plugs are std heat range (6). I understand how the plug heat ranges work........trikes

johnny yuma · 3 Jan 2007, 01:33 (Ref:1804401)

How well do the manifolds line up with the ports when tight? I just spent some time on a 179 holden and the inlet manifold for multiple carb setup was fine but the set of extractors is not all that precisely made and had to be encouraged with some force to bolt to the head in alignment with the ports.
Giving the hot gas a fence to jump on the way out just as bad as inlet jump.

THE engine builder who left the gasket debris on the deck should be sent to Port Arthur for retraining.Hopefully with your overall cleanup the 12 to 1 will sing like a bird. Let us know.

trikesrule · 3 Jan 2007, 09:47 (Ref:1804595)

Johnny and Ian and anyone who would like in on this 12:1 engine. I was just cleaning and running through the head bolt threads - no I didn't snap a tap. After I was happy with the threads I was cleaning the Deck surface with a new smooth stone and around every hole including the pushrod holes the metal has pulled (someone mentioned this not so long ago, hey Ian). How much I hear you ask? the front thread on the right has pulled 6 thou and the rest are three to four thou. The 6 thou one has rise spread out over an inch circle. It's about two inchs away from where it blew out. Between the head and the block thats 9 thou in that area. Strip and shave the block????????? But the compression will shoot up. (It's comon to take 20 thou off the top). Might be time for another block/engine. What are your thoughts.......trikes

knighty · 3 Jan 2007, 14:04 (Ref:1805163)

this is no surprise......most modern diesels (with high cylinder pressures) now feature counterbores around each head stud tapped hole in the cylinder block........this is in order to prevent exactly whats happening here - dont skim the head yet - I would reccomend you machine your cylinder block threads out to suit.....if your stud size is say 12mm....go for counter bores about 1.5 to to 2 mm bigger than the thread OD (therefore 13.5 to 14mm drill size) and 6mm deep - I have just looked at some drawings at work and this is exactly how they are done on a high performance turbo-diesel engine running around 180 Bar cylinder pressures - which is way more than your engine will be running.......needless to say - be careful with your stud torque specs and you may even need to drill and tap out the studs further in order to get the required thread engagement - as a rule for this sort of fastner you want a minimum of 2 times the thread OD for thread engagement - so for 12mm its a minimum of 24mm thread engagement.

knighty · 3 Jan 2007, 14:39 (Ref:1805193)

I have just had a rummage around at work and looked at some thread engagement figures into cylinder blocks - and the more I think about it - the more I reckon your head studs do not feature enough thread engagement into the block - in short probably all the block head stud threads have yielded and the block is scrap - not good news - you may be able to save it with some thread inserts - but dont count on it.

not only do you need to counter-bore the deck face of the new block - but you probably need to either increase the thread engagement by by adding another 12mm onto the standard thread depth - which means new longer head bolts too.

I retract the 2 times diameter rule ......sorry for the bum steer.......and would now say be in the region of 3 to 4 times the thread OD as a guide to thread engagement on head studs.

trikesrule · 3 Jan 2007, 19:27 (Ref:1805452)

Thanks Knighty. This block is 2mm short on material in critical areas working with your Formulas and from what I've found I think your dead right. I'll ask around and try and find out if Holden ever made a block with thicker decks. Johnny this deck is 19mm. I need it to be up around 22mm. Ever heard of a thicker deck for a 202/3.3?........trikes

ian_w · 3 Jan 2007, 19:44 (Ref:1805463)

Quote:

Originally Posted by trikesrule

The pistons 1 and 6 have pitting covering 1/3 of pistons surface headed toward left side (farthest from manifold) and 1/3 toward the exhaust.

Don't like the sound of the pitting - very likely to detonation damage.

I think you are on the right lines with getting the block re-faced. Knightys idea of counterboring the top of the stud holes a few mm is a good plan.

You shouldn't need to take more than a few thou off the block to clean it up. If you are worried about the comp ratio getting a bit high you can just take a small amount off the top of the piston crowns to compensate.

ian_w · 3 Jan 2007, 19:53 (Ref:1805471)

You can get pressure sensitive paper ( commonly called 'Fuji paper' ) that turns progressively red the more pressure is applied. It is ideal for determining if you are getting good gasket sealing.

From a very quick Googling I found this info - www.spare.it/lllw_man.pdf

Notso Swift · 3 Jan 2007, 22:32 (Ref:1805619)

Quote:

Originally Posted by trikesrule

Thanks Knighty. This block is 2mm short on material in critical areas working with your Formulas and from what I've found I think your dead right. I'll ask around and try and find out if Holden ever made a block with thicker decks. Johnny this deck is 19mm. I need it to be up around 22mm. Ever heard of a thicker deck for a 202/3.3?........trikes

I’m not a dinosaur man my self, but what about the VK motor? I know there was a lot of strengthening work for the fitment of fuel injection.

Pitting sounds like detonation too me

Can I ask what carb/manifold setup you have? Because if it is a single with 6 branches or twin with 3 branches you are going to be struggling to get even A/F ratios in each pot. If you can’t use an engine management computer and have different spark advance at each cylinder then you may need different compression ratios. The best way to tell will be on they dyno with a Lambda on each exhaust runner.

Notso Swift · 3 Jan 2007, 22:45 (Ref:1805631)

Of course, the Holden motor, does it hve a propensity to run hot at various points in the block? If so that will not help.
I suppose what I am saying with this, and the above comment about AF in each cylinder, is be aware of an average figure fooling you into thinking all the numbers are good.

johnny yuma · 4 Jan 2007, 00:26 (Ref:1805714)

It seems wrong to persevere with the shagged head and block when they are so cheap to buy.Work might as well be done on a less stressed lump of iron.

The VK with injection has a virtual 12 port head-don't know about the head bolts but the manifold stud pattern is different.

Last night I was reading the Muscle Car story with Ian Tate describing the development of the XUI and unless I'm wrong sounded like threaded dowels were placed in the block the head placed over these and suitable nuts torqued onto the protruding threads [think sidevalve flatheads] so that the block only has one force on it.

trikesrule · 4 Jan 2007, 09:40 (Ref:1805891)

NotsoSwift Class rules say single throat downdraft Stromberg and each leg of the manifold feeds two cylinders and yes the mixture traditionally runs rich in the centre and leanish at the ends with 2 and 4 pretty right. Sucks hey. Ummm different compression ratios - now theres food for thought. I was wondering the merits of different heat range plugs (today). But anyway lets get this guys engine fixed first. RE Thiker Deck. Found out today the Blue block has a 25mm deck vs 19mm in the red block (which this 12:1 has). Somebody asked me to describe a Graphite head gasket - it looks very similar to a 'normal' composite just a lighter gray. The 'new' engine shop I spoke with recommended them. Said when he retoque engine(s) he hardly gets any more on the torque wrench. Also said has used them with 13:1 and they seem to be fine. Only used them on 4' and V8' so far. Personally I'm headed to a MLS for this 12:1 engine Yep Notso Swift I'm going to have to sneak up on (not quite) max torque on the dyno. Hope this chaps cooling system is ok. Ian I'll ask around tomorrow for some of that paper - sometimes it's good to at things to see whats going on ( I have used bearing blue inthe past - messy). Johnny was Ian Tate talking about head studs? And yes I agree about this iron being stressed but I have to go with what hes got as there isn't time to build up another head. I'll talk to him about a new block etc but I hear he has the car up 4 sale. Guess he's had a gutful.......trikes

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