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Which means "Evil Twin". Lets see your projects where you change boring into fun or create the fun from scratch.
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PostPosted: Thu Sep 12, 2019 1:06 pm 
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Another Fiero guy just said that TS recommended against a gapless top for his 3.5 V6 destined for boost... I'd love to dig into the data, but they apparently think that thinner gapless tops are not good for boost. I wonder if piston oil squirters help that out by dropping the temp of the piston, which is the ring's heat sink.


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PostPosted: Thu Sep 12, 2019 1:13 pm 
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Just got a response recommending a gapless 2nd. I think they don't like thin top rings period but I followed up specifically asking about top ring flutter or reason to use the 2nd vs top. Keep you posted


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PostPosted: Thu Sep 12, 2019 1:49 pm 
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mk e wrote:
Just got a response recommending a gapless 2nd. I think they don't like thin top rings period but I followed up specifically asking about top ring flutter or reason to use the 2nd vs top. Keep you posted


The responses were short and a bit cryptic but the recommendation for street engines is gapless second. Ring flutter is the most over-used term they hear and can't happen below 8700rpm....which seems odd that its rpm not piston speed unless he meant 8700 in my engine with a 78mm stroke, but I told him my redline is 9500 so I'm not sure what to do with this.

They recommend the gapless top for race only application but have a handful of customers using it on the street, I asked why but have not gotten a response.


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PostPosted: Thu Sep 12, 2019 1:57 pm 
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hold the phone...poking around the website I found this:
http://03baea6.netsolhost.com/news/tota ... pany-sold/

They were bought by an equity firm in June which usually never ends well for the company that gets bought


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PostPosted: Thu Sep 12, 2019 10:18 pm 
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The new ring set came, yay


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PostPosted: Tue Sep 17, 2019 8:56 am 
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I Chatted with Ed from Totlal Seal last night, he was out last week. What he said was the gapless top is the best, it makes more HP and 10-15lbs more cranking compression and 3-6inHg more idle vacuum.

Then he went on to say that they've found it also has a tendency to cause excess oil consumption. He said the increased vacuum sucks oil though the guides on many engines so with any application that they aren't certain about, like a ferrari engine built from weld, they recommend the gapless second.

I remember I read something on speedtalk that seems like the answer. When the gapless no leak ring is in the second groove, the volume piston to wall down to the top of the 2nd ring is part of the chamber volume in the CR calculation....so you see more cranking compression, higher idle vacuum just like you would with an increased CR, becasue using a gapless top does change the CR, at least at lower rpm where the top ring .003 end gap is plenty big for the space below it to be active. I guess.


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PostPosted: Tue Sep 17, 2019 11:22 am 
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I think you're plenty capable of figuring out intake valve stem seals well enough to deal with slightly increased manifold vacuum...


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PostPosted: Tue Sep 17, 2019 11:57 am 
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Yeah, I'm not really concerned about that. My concern is that it appears to change the effective compression ratio, at least at lower rpm, and I don't know how close I am to the limit with my guess, and now increase with another .010" coming off the decks....that will increase CR to about 10.9-11.0 I'm guessing. I'm just not sure how much higher pump gas will go without issues for lower rpm/higher load street driving....that is where my concern is and I'm not sure its worth the risk of finding out.

Edit: I'm still finding the vacuum and cranking pressures odd....it seems too much to explain with the volume change and the oil use doesn't seem to make a lot of sense. There is no such thing as a race engine pulling stock engine vacuum...don't know.


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PostPosted: Tue Sep 17, 2019 1:41 pm 
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My Northstar is running 11.5:1 with 0.035" quench on pump gas with a fairly mild (high dynamic compression) 266 duration intake cam. It runs fine on 93 octane. I haven't tried any other fuel. That engine has a 93mm bore. It'll accelerate uphill from 1000 RPM in 5th gear.

What's your bore size? I know it's smaller than 93. Unless Ferrari's implementation of the basic pent roof combustion chamber is somehow unintentionally terrible, you should be completely fine with 11:1.

I also don't see the issue that Total Seal is worried about... I guess they've been groused at by a bunch of rednecks who put old heads with worn out valve stem seals over barrel shaped bores in shortblocks rebuilt with a dingleberry hone or something.


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PostPosted: Tue Sep 17, 2019 2:21 pm 
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The bore is 86mm, but my 0.050" duration is only 246/250 lobe or more importantly 241/247 valve.

What kind of cranking compression do you see? I was at 160 and climbing with 1 as high as 175 as the rings were starting to seat. 160-180 seems like its getting up there for pump gas.

DM says BMEP will be around 240psi or 16.3bar which is pretty high. Back when it thought this as a 920hp engine is was saying 18bar....I'm not sure that is a pump gas number and was afraid I'd need to play with things to stop detonation. More better cylinder filling means higher cylinder pressures. I have an electronic throttle so I guess I could always watch the MAP and not let the throttle open when it's too high along with pulling out timing and adding fuel but I hate to have to play those games.

I'm just really confused about what Total Seal Ed total me....I would believe his numbers as standard to gapless rings (1st or 2nd) but I'm struggling to understand how its physically possible gapless 2nd to gapless 1st. No place on their website is there any actual data, at least not that I could find and none was offed when I asked so....I don't know what to make of anything they say.


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