Can you call Mahle back and ask pointed questions as to exactly what the reasoning was to recommend the tighter 2nd gap? Seems like we are only guessing right now why the tech said what he said.

Let me pose this question to you.
What would be more daily driver than a bone stock LT1? Mahle pistons with a .018" top ring gap and .022" second ring gap. (going from memory and might be off a thou or two). And low tension oil rings...
That's all stock and it works wonderfully. It's hard to find an aftermarket set of rings that are as good as the stock LT1 rings for less than $200 bucks.

So exactly why would Mahle recommend a tighter 2nd ring gap for a daily driver if the opposite works so well for the bone stock LT1 which is daily driven by so many?

It would be good info if you can get them to give the reasoning.
thanks,
Karl Ellwein

 

I think we are talking about trivial differences. It's the absolute gap that counts anyway, not the relative gap of one ring to another.

Rich

 

well, actually, I think the relative gap between 1 and 2 is important and affects the ring function. I have very limited experience with it but the 2 ring sets I put in with the 2nd ring gapped tighter than the 1st resulted in poor seal (quality speed pro rings by the way which had recommended the 2nd ring gap be made larger than the 1st).

As soon as I looked into it a bit further and asked around and took the plung and installed as per the instructions then the ring seal was noticably better.

So anyway, what exactly was the Mahle reasoning for going with tighter 2nd ring as opposed to their instruction sheet?

Anyone want me to call? I have tomorrow off and can give em a call.

What number did you have for them?

Karl Ellwein

 

I would love for you to call them because I really dont know what I am talking about, so I cant quiz them myself very well. The number I used was 888-255-1942. I went to technical question or something like that, and the tech for number 2 on the dialtone, cuz tech one was away. So, please let me know what you find out!

I have a 385 stroked LT1, 11.21:1 compression, 16cc dished pistons sb125040I16. I have the rings set up at .018 and .016 becuase they said I would get better scraping and better oil control as its a strictly daily driver. I guess it wouldn't smoke like a bizzich when I got on it was is real answer, along with great oil control.. So, if you could do that it would be great! Any more questions so you have all the info you need to contact them?

 

Cool! That's enough info I think. Thanks for the number. I build engines as a hobby and need to continuously ask these questions so that I can squeeze some valuable tid-bits out of the schooled builders, (and so as not to get set in any one school of thought).

Hey, right now things like plateau hone technique, ring selection and gap just amaze me to no end.

But related to your ring gap, more ammo for the larger-second-ring-than-1st-ring-gap is the fact that factory bone stock LT1's have Mahle pistons and high quality rings and the 2nd ring gap is larger than the 1st and they have superior oil control and very low tension while doing it. There has got to be something said for that.

Karl

 

It will be very interesting to hear what you find out! I will bring my laptop to work tomorrow, as that is where I am building the motor, that way I can check this thread to see when you list the answers. I am trying to get it all clearanced tomorrow, then pulled apart and all cleaned up for painting the block this weekend. Then monday it will all start goin together for good.

I too dont want to get stuck in one train of thought. But, the guys I work with said even at .016" on the bottom, there is a 99.999% chance that I would ever have problems with it. So, I am at a loss. We will see what you find out tomorrow! Thanks again!
~Cody

 

The absolute ring gap for the second ring is the variable. It's a misnomer to talk about it as if the relative gaps were what is meaningful. What we are really talking about is "how big should the second ring gap" be. No one is suggesting changing the top ring gap (I hope). For the engines most of you guys are talking about, opening up or closing the second ring by a couple of thousanths will make NO DIFFERENCE that you can detect. You are wasting a lot of mental energy. But have at it if it amuses you.

Rich

 

Very true
I agree, street application so no difference will be noticed no matter what school you enrolled in...

 

Rich, You are talking about an absolute gap but some of us are talking about the relative gap.
I did see a big difference on a very mild 383 LT1 stroker.
For years I had it (not in accordance with the new school 2nd ring gap larger prevents ring flutter theory). Never did have a good ring seal. Was workable but not good. The moment I went to the larger 2nd ring than 1st ring gap (with the same brand of speed pro rings) the ring seal worked perfectly. Same machine shop doing the hone, (Samakow Racing Engines). The dude, Terry Samakow, isn't a hack with honing cylinders.

Question. At what point are we allowed to concern ourselves with the best ring gapping technique? Do we have to be the 2005 Popular Hot Rodding Engine Master? (they all used the 2nd ring gap greater than the 1st ring school). For our lowly applications it just doesn't matter what rings we use probably? I say street engines need just as good a hone job and ring quality as any race engine. And if the rings are not gapped I.A.W. the ring manufacture instructions then they won't work as well and it WILL be noticed.

Karl Ellwein

 

Karl: I don't want to get into a pissing match. But you are wrong. You changed the gap on the second ring, and I am glad it worked for you. You would not have accomplished the same thing if the second ring were kept the same and you tightened up the top ring. All you have then is the wrong top ring AND the wrong second ring gap.

I find it hard to believe that a couple of thousanth difference in the second ring gap made a huge difference in how your motor ran. But it's rational to discuss what you observed and I respect it. Just try to keep the terms straight to avoid confusing people. Like I said, to the uninitiated if you keep talking about the relative gap between the top and second rings confusion may result and a mis-assembled motor could be the consequence.

Rich

 

Had a good talk with Trey at Mahle,
2nd ring gap should be wider than the 1st and it's because of all the reasons already discussed.
The .016" mentioned was appeasement.
And Rich is 90% right that it wont matter that much but also 10% wrong because it does matter at least a little bit.

Over the long run and for a street motor you'll have a better ring seal and just as good of oil control with the wider 2nd ring gap to the 1st ring gap.
(according to Mahle which matches the latest trend in ring gap theory).

So if you are trying to get the most out of your hot street project then maybe it would be best to go with the .022" second ring gap.

(it keeps the 1st and 2nd ring flat on the piston land by going with a wider 2nd ring gap relative to the 1st ring gap. Sort of a combustion gas relief that helps to resist ring flutter).

So whatever you want to do, at least you have some opinions.

Karl

 

grr, so .018 up top, and .020 or .022 on the bottom? does it matter? I would like to keep them as tight as possible, as they will wear eventually. I would like to know now, the block is dirty from clearancing and I can fit rings now before painting it.

Pm sent quickss

 

If they are a little looser that's probably better. Some people get crazy on tight gaps and it doesn't always make more power that way. I do like the looser 2nd gaps as well.

Bret

 

Just to throw my .02 into the bullring.

I gap the bulk of my N/A 383's at .018 Top and .020 2nd. 9 out of 10 are using moly tops rings and cast seconds.

 

cool. that is what I did, .018 up top, and .020 down low. Woohoo, see, it does help to bounce ideas off one another. Its just some people take things too literally, or seriously, and testosterone kicks in. hehe. So, woohoo, we did accomplish something here, be proud!