<VV> Ceramic Coatings Vol 45, Issue 78

Mon Oct 27 00:26:30 EDT 2008

> > > ------------------------------> > Message: 4> Date: Sat, 25 Oct 2008 21:53:59 -0700> From: kevin nash <wrokit at hotmail.com>> Subject: <VV> Ceramic Coatings Questions (Kevin Nash)> To: <virtualvairs at corvair.org>> Message-ID: <BAY109-W4480EE4FB83F6E3D48CBD7D3250 at phx.gbl>> Content-Type: text/plain; charset="iso-8859-1"> > > > From: virtualvairs-request at corvair.org> Message: 3> Date: Sat, 25 Oct 2008 13:58:38 EDT> From: RoboMan91324 at aol.com> Subject: <VV> Ceramic Coatings Questions> To: virtualvairs at corvair.org> Message-ID: <d4c.333801f1.3634b84e at aol.com>> Content-Type: text/plain; charset="UTF-8"> > Gang,> > I have been thinking of using ceramic coatings in a rebuild I am doing and I > have a few questions. These are as follow.> > 1. Since the head will be thermally insulated from the heat of the > combustion chamber, how will this effect the warm up period of the engine?> > 2. Since the pistons will be insulated from the heat, they will expand less > and/or slower in the cylinder. I believe that the expansion of the piston > is assumed to be a certain amount when the diameters of the piston and > cylinder are set. Is this an area of concern?> > 3. The engine I am rebuilding is a 180 turbo. Am I correct to assume that > I need to also coat components in the exhaust side of the turbo to protect >> them from the increased exhaust heat? If so, which components? Also, will the > thickness of the coating cause an interference problem between components > and/or balance problem on the rotating member?> > 4. I assume that the exhaust pipe components must be thoroughly cleaned > before the inner surface is to be coated. Is it practical to coat the inside of > the muffler considering that the inside can't be thoroughly cleaned?> > 5. If I do not coat the interior of the muffler, how much hotter will it > get with this setup and will the increased temperature cause a problem with > surrounding components and paint? Also, what reduced life span can I expect for > the muffler if it is unprotected?> > I guess that is enough for now.> > Thanks in advance,> > Doc> 1960 Corvette; 1961 Rampside; 1962 Rampside; 1964 Spyder coupe; 1965 > Greenbrier; 1966 Corsa turbo coupe; 1967 Nova SS; 1968 Camaro ragtop> **************Play online games for FREE at Games.com! All of your favorites, >> no registration required and great graphics ? check it out! > (http://pr.atwola.com/promoclk/100000075x1211202682x1200689022/aol?redir=> http://www.games.com?ncid=emlcntusgame00000001)> > Doc- I have been following the recent threads on thermal barrier> coatings ("ceramic coatings") with some interest, as I had had this done on my early turbo a few years ago> and had some problems with it- I had been meaning to reply to earlier> posts about this, but time constraints havent allowed me to do so> untill now. In my case, I had the combustion chamber, valve faces and> exhaust ports coated only, and had the true static compression set> at 8.2:1. The company that did this (Swain Technologies) recommended> that the timing be retarded 6 degrees, to compensate for the .6 of a point rise in effective compression ratio rise. The effective compression> ratio rise is due to the fact that the cylinder head traps more heat (because of the thermal barriers) and more heat on the compression> stroke will cause it to ping easier. In my case, my effective compression> ratio was 8.8:1 !! When I got my car back together, I really wished that> I had done something different than i did, as it was very prone to > pinging when not under boost. Under boost, it was screaming fast,> not under boost it would ping if i suddenly accelerated. No matter> how much I retarded the timing, it would ping, as it made the head> temperatures rise, and no matter how rich the carburator was, (i remember at one point getting only 13mpg just cruising along) that> mother would ping when i nailed it too hard. A friend of mine had> a late model turbo with thermal barriers in the combustion chamber> and had the same sort of problems ( and had tried unsuccesfully to> fix it the same way I had). If you want good success with your > thermal barriers, you will DROP your compression ratio from stock> 1 point!! if you try to keep the stock compression ratio and add the> thermal barriers, you will have weird pinging problems that you wont> be able to tune out!> I will answer your specific questions in a later post, as my fingers are > getting a little tired.> Kevin Nash> 63 efi spyder> > > ------------------------------> 

Okay, I'm back- answers to your specific questions:
1) The warm up period is shortened, but you wont be able to tell by
    looking at the head temperature gauge, as it is on the other side
    of the thermal barrier coating (t.b.c). I suppose that the right way
    to tell if a engine is warmed up is to install a oil temperature gauge
    and wait for the temperature to come into range, but my warm up
    method is to watch the oil pressure rise, and wait untill it peaks,
    then I drive, taking care to drive it easy untill i see the head     temperature get to 300 degs- then i figure, its warmed up
2. Yes, the pistons will expand less if you coat the top of the pistons,
    and ideally you would want to have the clearances reduced somewhat
    to compensate for that. How much the clearances should be reduced,
    I dont know, because it totally depends on the formulation of the coating, and only the coating company will know that.
3. No, you do not need to coat the inside of the exhaust turbocharger,
   nor is it recommended because of clearance and balance issues. 
4. For performance reasons, you should not coat the inside of the muffler,
    practical or not. By trapping heat within the muffler, you are creating
    additional back pressure. 
5. I dont know how much hotter your muffler will get, but consider- the
    hottest your muffler will ever get is when you are developing full boost- but that condition never happens unless the car is moving, so
the muffler and surrounding items are cooled off from the air flow from
the rear wheel well, and when the engine is running but stationary, 
the exhaust temperatures at the muffler never get very hot. Also,
since mufflers typically do not fail because of heat ( they eventually
rust from the inside out from water condensation) I would expect your
muffler life to increase, as the extra temperature would tend to dry out
the muffler more quickly! 

Kevin Nash
efi 63 spyder
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