Twin Spark Engines

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kterkkila
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Re: Twin Spark Engines

Post by kterkkila » Sun May 27, 2012 11:16 am

Giuliettaevo2, Yes, the guides and their seals are in good condition. I also don't think that this amount of oil could be gone through valve guides even with relatively worn guides with sufficient valve seals. But this is just my thinking.

The oil escape drills behind the oil ring must be a good idea and 16V engine doesn't seem to have much of those. On my 8V JE pistons, there are 6 or 8 holes, but maybe more would be better? Good proposal anyway.

I have also been thinking about lateral gas porting for top compression ring, which could change it's behavior, but this is again blind shooting without knowing what's happening.

Mike, In this engine, there's no oil coming out of breather. Now when it eats one liter per 6 hours or 210 laps on 1:35 long track (including pit stops) at full speed, it would be equal to 0.5 dl on 10 lap race, which would be quite hard to notice from dip stick. If revving around 7000, oil consumption is something like double. It also seems that oil consumption is bigger on longer runs when engine is really hot, so there's not much oil consumption on test sessions.

Just wondering, why some say that 22 m/s piston average speed is typical for endurance racing and 25 m/s for short races? Like this one:
http://hpwizard.com/mean-piston-speed.html

With 88.5mm stroke 22 m/s would be equal to 7460 rpm. So in my case
- 20m/s (6780rpm) -> oil consumption is OK
- 21m/s (7120rpm) -> oil consumption is too high, might survive on a race or not
- 22m/s (7460rpm) -> dead engine, around 1 liter per hour..
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Re: Twin Spark Engines

Post by kterkkila » Sun May 27, 2012 11:30 am

Kevin, The oils I have tried are Castrol TWS 10W-60, Motul 5100 MC 15W-50 and Motul 300V LeMans 20W-60. I wouldn't be surprised if some other oil would stay better on the engine, but there's no information available on that side. The 1 liter is OK, but 2 liters would be too much. If we need to add oil, it cannot be done same time when adding fuel. On some race track we have to drive slowly to separated service place which would mean losing around 5 min. On some other tracks there's no need to drive that much, but it's easy to use 2 min when doing anything under the hood.
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Re: Twin Spark Engines

Post by kevin » Sun May 27, 2012 12:33 pm

Well you tried the whole range of oil the guys use here so you have covered all those bases . But that consumption of 1 litre is not bad at all looking those kms you did at high rpm .
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Re: Twin Spark Engines

Post by MD » Sun May 27, 2012 1:23 pm

Kimmo,

The TS engine has an oil level sensor as you know. Why not live with the oil consumption and simply create a back up oil tank to top up the engine automatically by using the oil level sensor?

I would see this as only working when the car is stationary to keep the level constant but it could electrically be activated during refueling to save time.

All this with the proviso that it was not a rule breaker.. :D
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Re: Twin Spark Engines

Post by kterkkila » Sun May 27, 2012 2:41 pm

Funny idea, but actually I used that with Mazda racer 10 years ago :)

But it's not allowed.. I have been using the sensor to check if we need to stop for oil filling, but now the rules changed so that oil level can be checked while adding the fuel, so no need for that anymore.
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Re: Twin Spark Engines

Post by Mats » Sun May 27, 2012 11:19 pm

I have never seen a working sensor, do they even exist?
I'm moving my dipsick to that location because the turbo deletes the old placement.
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Re: Twin Spark Engines

Post by kterkkila » Mon May 28, 2012 10:05 am

Mats wrote:I have never seen a working sensor, do they even exist?
They are rare but from what I have got on my hands, maybe 2 out of 5 have been still working. The one I used last time was from 3.0 V6 164, because it was shorter. The system gave alarm if the oil level was below half. But that sensor also failed last summer and now I don't need the system anymore.
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Re: Twin Spark Engines

Post by MD » Mon May 28, 2012 10:54 pm

Kimmo

The link above doesn't want to load the page. Tried it a number of times, same result.
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Re: Twin Spark Engines

Post by Mats » Tue May 29, 2012 12:08 am

MD wrote:Kimmo

The link above doesn't want to load the page. Tried it a number of times, same result.
The HPWizard link? Works like a charm here... :?
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Re: Twin Spark Engines

Post by MD » Tue May 29, 2012 1:48 am

Typical response

Internet Explorer cannot display the webpage

What you can try:
Diagnose Connection Problems

More information

This problem can be caused by a variety of issues, including:

•Internet connectivity has been lost.
•The website is temporarily unavailable.
•The Domain Name Server (DNS) is not reachable.
•The Domain Name Server (DNS) does not have a listing for the website's domain.
•There might be a typing error in the address.
•If this is an HTTPS (secure) address, click Tools, click Internet Options, click Advanced, and check to be sure the SSL and TLS protocols are enabled under the security section.
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Re: Twin Spark Engines

Post by Mats » Tue May 29, 2012 3:01 am

Have you tried any other browser then Internet Destroyer?
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Re: Twin Spark Engines

Post by MD » Tue May 29, 2012 1:52 pm

Yes, Mozilla-Firefox. Same deal. It wont even open from search results.

Kimmo, could piston side thrust be an issue?

I would think what ever experiments you try, you would need to do it on an engine dyno so that you have controlled conditions. Elements like G forces could be eliminated to start with.

This is getting into engine development stuff that manufacturers go into and have the facilities. Cannot imagine your budget would stand for that.
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Re: Twin Spark Engines

Post by Duk » Wed May 30, 2012 3:27 am

MD wrote:Yes, Mozilla-Firefox. Same deal. It wont even open from search results.
Without want to deviate to much from the real subject, I think you are suffering from shite Australian internet. It happens to me sometimes when trying to view international websites and at all sorts of times of the day and night (occasional insomnia is a bitch).

The link works for me, tho.
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Re: Twin Spark Engines

Post by kterkkila » Fri Jun 01, 2012 9:41 am

MD wrote: This is getting into engine development stuff that manufacturers go into and have the facilities. Cannot imagine your budget would stand for that.
Yeah, unfortunately I have to go too deep on development.. I think it's time to design new pistons, again..
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Re: Twin Spark Engines

Post by kterkkila » Tue Dec 25, 2012 3:22 pm

Have anybody tried low viscosity synthetic racing oils on these old engines? How tight the bearing clearances could be? The main and rod bearing clearance specs are quite wide, meaning 0.004..0.047mm for mains and 0.027..0.062mm for rod big ends. The mains especially are allowed to be really tight. I understand that if going too small clearances, the cooling of the bearings will be reduced and there's less margin for flexing parts, and in worst scenario it's possible to spun the bearing on start up. But it's also understood that lower viscosity would be beneficial on terms on efficiency. The oil drag on bearings is one thing, the amount of the flying oil on the crank case is another and the need for the oil pump capacity is the third reason for looking possibility to go on thin synthetic. Maybe 0.01..0.02 for main and 0.02..0.03 for rods combined with 5W-40 or 5W-30?

Another question is, have someone faced any bearing lubrication problems on TS racing engines? It seems that main have been intact and rod bearing OK as well. I don't have drilled direct feed for the two main bearings which are getting their oil via crank, even if that seems to be a popular mod on these engines.

Is there any racing bearings available (material options, narrower, groove lengths, blue printing sizes etc..)?
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