Question for turbo guys

[RichFox]

In about 1979 I had my twin turbo 270 Gmc blowing through a 780 Holley and Jahns cast pistons. It was death on pistons. At the time I was working for the Plasma Spray people so I sprayed my piston tops with (as I remember) Metco 601 ceramic. At the same time I did my turbine housings and combustion chambers to keep the heat in instead of dumping it into the water jackets. I did the housings cause it looked neat. My question is, Do people still do that? I never hear about it any more. Why not? Seemed to work very well on the pistons at least.

[jl222]

In about 1979 I had my twin turbo 270 Gmc blowing through a 780 Holley and Jahns cast pistons. It was death on pistons. At the time I was working for the Plasma Spray people so I sprayed my piston tops with (as I remember) Metco 601 ceramic. At the same time I did my turbine housings and combustion chambers to keep the heat in instead of dumping it into the water jackets. I did the housings cause it looked neat. My question is, Do people still do that? I never hear about it any more. Why not? Seemed to work very well on the pistons at least.

  Been wondering the same thing, maybe it retains to much heat and causes other problems. We had a problem streching our valves at speedweek caused by something, even though the EFI showed plenty rich but maybe a little retarded and the supercharged air was cooler than ever. We've always ran water injection in the past and never had streching the valve problems, so were going back to water injection.
  Didn't WW2 engines chrome the valve faces [ I think they called it bright trey]?

                          JL222

[RichFox]

Don't know about chrome. I ran water also. It sure seemed like a good idea to coat the chamber. I know if a piston did melt it really let go, but they lived a lot longer than without the ceramic.

[4-barrel Mike]

Maybe if you ran a bigger turbo??



Mike

[jl222]

  WOW   Looks like a spare one in the middle. What are they for?

                  JL222

  Looking closer those might be centrifugals...hmm

[Dean Los Angeles]

Wow! You gotta think that thing is going to suck in birds and rocks.

How does it work when they are pointing in different directions.

Where do you put in the giant mail tube?

[1212FBGS]

looks to me like it could suck in an ex wife...... where's that thing at??
kent

[bbarn]

We'll get RobFrey to post something, this is right up his alley. I believe he did ceramic coatings on the lakester project.

[robfrey]

I don't know a everything about ceramic coatings but let me try my best.
We do coat piston tops and sometimes the ex housings but that is mostly for cosmetic reasons.
I have been using Swain Tech with pretty good results. I don't know how much it is helping as I've only not used it one time (piston coating). I figure it as insurance.
J222, you can melt ex valves and really raise egts by going too conservative on timing.
I've really had a lot of luck by using Performance Trends Engine Analyzer 3.9 to get my timing curves. I truly think it has been the difference with us keeping things together and making big power. I highly recommend this product. Kenny Duttweiler uses it so it must not be too bad.
I have yet to melt a piston or have any major problems. I have warped a few ex valves but we don't worry about this too much. We have learned not to shut down the engine too fast and that solved a lot of our problems. Now when we warp a valve, we just run her hard again and beat it flat again and it usually fixes it again as evidence of the leak down test. We have been using the Ferrea inconel ex valves with pretty good luck. We have also not ever seen any hint of detonation in the last three years.
I also highly recommend an on board egt gauge hooked up to a warning light. Set it at 1650°f for supercharged cars or 1800°f for turbo cars If you see the light, abort the run. Fix the MAP and try again.
Of all the things I've mentioned, the computer simulation with Engine Analyzer 3.9 will make the most difference on durability.

http://performancetrends.com/download.htm#eapro

I'm not big on water injection. Water make steam which displaces usable oxygen in the chamber and robs power but it will bring egt's down.

[robfrey]

BTW, Engine Analyzer 3.9 will give you projections of egts and I have found that to be helpful.

[jl222]

  Rob...good idea on Egt light how do you set that up [to light up at a certain temp]? We were only 2 deg less on timing than I used to run but going back. Sir Harry Ricardo did extensive reserch on water injection for use on WW2 AERO ENGINES with amazing results lowering intake temps [which shrinks the air and lets more air in] and testing water and steam seperatly showing the benifits of steam in preventing detonation. Look at chart under water injection thread. Aero gasolines go buy performance numbers 100 octane /130 or 100/130 means by running the engine at the rich setting gives you 130 octane
They also had 115/145 with water injection it gave them a performance number of 115/170

                JL222

                    

[robfrey]

John,
We used this egt gauge on the lakester. I was pretty happy with it's performance.

http://www.summitracing.com/parts/ATM-3647/

The steam will help detonation but so will a healthy icewater intercooler and you will not be displacing any oxygen.
What kind of air inlet temps were you seeing? We get our down to about 58f at the end of a long dyno pull. It's hard to detonate air that cold especially at 23 psi and 8.5 comp w conventional BBC heads. This combo does yield over 2000hp (at crank) with a real safe tune (about 11.5 to 1).

[RichFox]

At the time i was running turbos it was kind of before EFI. Don't think I had ever heard of it. I just had a sealed container with water in it and a line to the intake manifold. Got boost? Got pressure in the container which pushes water to a nozzle in top of the carburetor. Very simple but effective. Don't forget, at that time I pretty much thought most parts had to pay their dues as a OEM part before I brought it home from the junkyard for the race car.

[jl222]

John,
We used this egt gauge on the lakester. I was pretty happy with it's performance.

http://www.summitracing.com/parts/ATM-3647/

The steam will help detonation but so will a healthy icewater intercooler and you will not be displacing any oxygen.
What kind of air inlet temps were you seeing? We get our down to about 58f at the end of a long dyno pull. It's hard to detonate air that cold especially at 23 psi and 8.5 comp w conventional BBC heads. This combo does yield over 2000hp (at crank) with a real safe tune (about 11.5 to 1).

  Rob if you cool the air with water before the intercooler it shrinks the air allowing more air with oxygen in it. We also have a big icewater intercooler and were seeing 50 degree temps for about 30 sec then climbing to 140 degrees with air/fuel high 10s low 11s. and 36 psi

            JL222

[robfrey]

Hmmmm, The problem is that 140 degree air is occurring at the worst possible time.
That's why I like turbos because I can budget my heat via boost controller but keep in mind, I have not done this real successfully yet. Just saying "in theory".
You may want to look at the latest intercooler technology as things have changed recently. The cores have gotten smaller and only work if you exchange the water very fast, but as long as you have enough ice water, they won't heat soak. 36 psi is a lot of boost!