E36 S50/S52, single VANOS, and VANOS shims.

[aeronaut]

EDIT: To clarify for future readers, my original description in this post was way wrong.
NeilM summarizes the actual function of VANOS well in post #18 of this thread. And this
thread has a good description of why retarding intake cam timing at high rpm is
a good thing: "https://www.m5board.com/threads/how-does-retarding-cam-timing-make-more-power.53403/#post-539761"

************************************************** ****************
Making sure I understand this.

The basics:
On an S50/S52 single VANOS engine, VANOS changes valve overlap by changing intake cam timing.
In general, more exhaust/intake overlap increases high rpm power.
And less exhaust/intake overlap increases low rpm power.
So VANOS retards intake timing at low rpm and advances intake timing at high rpm.
Advancing intake timing increases risk of piston/valve contact.

Now let's talk modifications to cams and VANOS:
Adding a shim in the VANOS decreases the maximum amount of advance it makes to the intake cam, reducing the amount of overlap when compared to the normal (non-shimed) VANOS.

So, assume I put big cams in which help high-rpm power a lot, but if i don't change pistons I might have piston/valve contact, so I add a shim to the VANOS which reduces power at high rpm...but not nearly as much as the big cams add.

Did I get that right?

[mslevin]

Following for info, but yes this is my understanding as to how VANOS/shims work.

[pbonsalb]

Makes sense to me. Losing a few degrees of vanos is more than offset by wild cams. What are you thinking for cams?

[aeronaut]

I've talked to VAC (they love selling shit, but I get that), and Achilles (like 180 deg different than VAC), so am still sorting through it all. I'd be happy with my stock cams, but they are showing wear and I want to button this engine up and not touch it for 5 years. Above all else, reliability over HP.

Schrick 264/256 are "only" $1200 now. And Achilles says run stock springs and valves, and if I want to add margin, run a VANOS shim.
But, Schrick 276/270s are only $200 more, $1400. But that would require springs and valves and VANOS shim (if stock pistons).

Of course, part of me says to do valves and springs ANYWAY. But Achilles really says it's not needed. And Achilles says lifters are a problem too.

Rabbit hole!

[pbonsalb]

I run the 264/256. Zero downside to those. I don’t think they give up any low to mid range power. They also add only a modest amount over S52 cams. I think the dynos I have seen show around 10 rwhp. The 276/270 probably add at least 50% more but do trade low to midrange power. Also more likely to require valvetrain work and vanos limitation. On a 20-25 year old motor you track, you should probably refresh the valvetrain.

[aeronaut]

I run the 264/256. Zero downside to those. I don’t think they give up any low to mid range power. They also add only a modest amount over S52 cams. I think the dynos I have seen show around 10 rwhp. The 276/270 probably add at least 50% more but do trade low to midrange power. Also more likely to require valvetrain work and vanos limitation. On a 20-25 year old motor you track, you should probably refresh the valvetrain.

Good info. Sounds like the 264/256 is a good choice for me. Over the years, I've loved it when the P-car or Vette guy comes over and asks what engine I have, and I get to say STOCK internals, 212WHP on the dyno. Damn it, won't get to say that anymore. Maybe I'll come up with words like "no more than the HP it had in 1995". lol.

Yea, I probably should refresh valves & springs I know. I had pretty much convinced myself to. Until I talked to Achilles. They are saying almost the opposite. Run it, it'll be fine, even up to 7400rpm now and then. Just don't money shift.

[pbonsalb]

Achilles knows more than me about racing these motors. I think for a track car, the bigger cams would be preferable.

[aeronaut]

Achilles seems to really look at the S50/S52 as an all or nothing engine. He says to 'really fix' the weakness in the top end (which is valve/piston clearance) valves, springs, and pistons need changed to get the performance and clearance right. I like that they look at this as a system rather than a list of parts they're figuring out how to sell me. But then, it's hard for me to understand if there's an in-between solution that's good for me.

Here's where my head is right now (luckily this isn't about being cheap, but rather trying to pick the right parts for what I want).
One of the 2 following setups:

Option 1: 264/256 cams, lifters. Leave everything else as is.
Option 2: 276/270 cams, lifters, springs, valves, (VANOS limiter if needed) and increase redline to 7400. BUT, achilles will say this really doesn't FIX the risk of blowing up the engine (my paraphrase of 30 min discussion).

I'd love to have that extra 400rpm.

It seems Supertech valves and springs are the go to?

[jayjaya29]

Vanos shims will reduce LOW rpm power. Vanos is activated at low rpms (putting the valves closer to the pistons) and is turned off at high rpms. So if you shim your vanos to run big cams you will still see the full benefit of cams (high end power).

[aeronaut]

Vanos shims will reduce LOW rpm power. Vanos is activated at low rpms (putting the valves closer to the pistons) and is turned off at high rpms. So if you shim your vanos to run big cams you will still see the full benefit of cams (high end power).

So VANOS advances intake cam timing at low rpm?
This would increase valve overlap, which traditionally at least, decreases low rpm power.

- - - Updated - - -

Ok, I'm confused. But..just found this statement on TRM blog:

"If you are looking for more peak power, and it looks like things will respond well to retarding the cam more, that does a few things. Retarding the intake cam will move the power to the right..."

Retarding intake cam relative to exhaust decreases valve overlap, which according to the above statement, increases high rpm power.

[aeronaut]

Well, I guess it's a big it depends, I find all various statements on what affect valve overlap has on engine power location.

"Typically, narrower lobe separation develops peak torque at lower rpm and widening the separation [decreasing overlap] tends to build peak torque higher in the rpm range."
vs
"As overlap increases, this tends to make the engine idle quality more erratic or lumpy, while improving mid-range and top-end power."

[aeronaut]

Ok, SO, if VANOS advances intake timing in low rpm range, and retards it in high rpm range, then the most likely place for valve/piston contact for a high lift cam would be in lower rpm (or severe overrev). So, then, with cams that require a VANOS shim, that's really preventing piston/valve contact at low rpm.

And, found the post below. Which makes sense. Basically supports the fact that it's best for high rpm power if input cam timing is retarded. In short, at high rpm, ideally the cam would open sooner AND open later. But opening it later adds more power than opening it sooner, so with a fixed cam profile, retarding the intake cam timing has MORE affect than advancing intake cam time.

2nd post:
https://www.m5board.com/threads/how-...e-power.53403/

So, if this is correct, and if VANOS allows intake timing to retard at high rpm, my first post is allllll wrong.

[aeronaut]

Wait, if VANOS fully retards intake timing at high rpm, then adding a VANOS shim does NOTHING to protect engine at high rpm or over rev.

[jayjaya29]

Ok, SO, if VANOS advances intake timing in low rpm range, and retards it in high rpm range, then the most likely place for valve/piston contact for a high lift cam would be in lower rpm (or severe overrev). So, then, with cams that require a VANOS shim, that's really preventing piston/valve contact at low rpm.

Nailed it on the head.

[pbonsalb]

Option 1: 264/256 cams, lifters. Leave everything else as is.
Option 2: 276/270 cams, lifters, springs, valves, (VANOS limiter if needed) and increase redline to 7400. BUT, achilles will say this really doesn't FIX the risk of blowing up the engine (my paraphrase of 30 min discussion).

I'd love to have that extra 400rpm.

It seems Supertech valves and springs are the go to?

What does Achilles say about an ATI damper? Or do they just say the S52 crank and bore don’t like high rpm? I use 7200 rpm, but my car is a street car. Years ago I sold a used crank damper to a racer who said the dampers last a long time with a 7200 limited but fail sooner with 7400.

I have Supertech springs and retainers and +1mm inconel exhaust and stainless intake valves (extensive port work included deshrouding). Some say Supertech quality is spotty.

[aeronaut]

I forgot to ask about the damper, damn it. He didn't mention any issues with the damper at 7400, but if I call back I'll definitely ask.

- - - Updated - - -

Nailed it on the head.

Thanks, I'm catching on.

[aeronaut]

If not Supertech, then?
Ferrea?

[NeilM]

Ok, SO, if VANOS advances intake timing in low rpm range, and retards it in high rpm range

Not quite.

At low engine speeds, intake valves open late, ensuring smooth engine operation. As engine speed increases into the mid-range, intake valve timing is advanced by the VANOS, resulting in increased torque, improved drivability and reduced emissions. At higher engine speeds, intake valve timing is once more retarded, for better power and performance.

So low and high rpm valve timing are the same, while midrange gets advanced by the VANOS. (Timing changes are on/off, not continuously variable, with the single VANOS system.)

Neil

[pbonsalb]

That is what I understood. Retarded at idle, advanced above idle (but I don’t know the rpm) and then retarded again around 5000 rpm. What I did not think about until jajaya29 explained it is that the vanos travel limiter is affecting only the advance so it won’t take anything away from the power added by hotter cams.

[aeronaut]

Magic sauce!

Again, thanks for the insight.

[aeronaut]

What does Achilles say about an ATI damper? Or do they just say the S52 crank and bore don’t like high rpm? I use 7200 rpm, but my car is a street car. Years ago I sold a used crank damper to a racer who said the dampers last a long time with a 7200 limited but fail sooner with 7400.

I have Supertech springs and retainers and +1mm inconel exhaust and stainless intake valves (extensive port work included deshrouding). Some say Supertech quality is spotty.

Talked to Achilles again, he said they have no problem with the stock damper. I asked at what rpm it failed, and he didn't quite answer my question but seemed comfortable with 7400. He said as long as the stock damper is in good shape (balanced, not warped, etc), it would be fine. I also get the feeling he has the race engine mind set, as in, the damper would be fine, until it's not. So take all this with the understanding this guys builds race engines.

[21deep]

I’m so glad this thread came out. I’m actually in a similar boat here. I bought an 318is that has an M3 drivetrain (s52 with transmission, subframes, diffs, brakes). Anyway, it has a reground cam in it and I have no clue what the lift and duration is. The guy who built it also forgot what he put in there because he had several built e36’s. He unplugged the Vanos to deactivate it to prevent any problems. After I rebuild the Vanos with besian seals and anti rattle kit, I want to shim it so that I can use it again. Since I don’t know what cam I have, I’m having a hard time figuring out what size shims that I need. Any help or guidance for me?

[aeronaut]

Wish I could help, but a specialty machine shop can measure your cam profiles and give you duration and lift numbers. There are other ways, like measuring the actual valve/piston clearance, but that's not trivial.

[bimmerboy318]

Option 1: 264/256 cams, lifters. Leave everything else as is.
Option 2: 276/270 cams, lifters, springs, valves, (VANOS limiter if needed) and increase redline to 7400. BUT, achilles will say this really doesn't FIX the risk of blowing up the engine (my paraphrase of 30 min discussion).

Based on what I've read here... it sounds like an Option 3 would "fix" the money shift issue?

Option 3: 264/256 cams, lifters, springs, and Vanos limiter. Or if rebuilding motor, no Vanos limiter but valve reliefs on the new pistons. I'll be giving Achilles a call to discuss such an option. Because I think the weakness of the S5X motors is the money shift above all other things.

[ScotcH]

Based on what I've read here... it sounds like an Option 3 would "fix" the money shift issue?

Option 3: 264/256 cams, lifters, springs, and Vanos limiter. Or if rebuilding motor, no Vanos limiter but valve reliefs on the new pistons. I'll be giving Achilles a call to discuss such an option. Because I think the weakness of the S5X motors is the money shift above all other things.

It's a weakness of any interference engine ... which is probably 100% of modern engines. You probably can't get valve pockets deep enough to eliminate the issue, but it can be reduced for sure. I overreved my build m54 to 12900 rpm. There was no valve contact, but the vanos sprockets broke apart. This was with massive piston pockets, supertech springs, and solid lifters (which help with the valve float a lot). So it CAN be helped, but I think I still got very lucky that it didn't grenade the engine.

I think you you should not worry about the $shift, and just build the engine in a proven way ... it can happen, but if you back-hand the 3->4 shift, it's pretty unlikely.