To Vanos or not to Vanos...

[lifeiskaos]

nv for boost if you are too cheap to have it tuned, too scared of tuning an on/off switch, or too stupid to unplug vanos

fixed.

I don't mean to be a dick, I just do not understand why everyone says NV are boost friendly, besides the extra 2 PSI you could run before you need to lower the compression

[z31maniac]

I was only referring to rattly, 15 year old vanos units.

That can be fixed with $30 in seals or $150 for a Dr Vanos unit.

You're right. Definitely a reason to avoid them.

[Wh33lhop]

That can be fixed with $30 in seals or $150 for a Dr Vanos unit.

You're right. Definitely a reason to avoid them.

I've heard of some instances where the Dr Vanos kit works, some where it doesn't. It's one less thing to worry about, but I don't really care enough to argue further. I already conceded that by the numbers, the TU is the better motor. I settled for the NV because one popped up close by, I like the high-end motor feel and the vanos rattle that I'd read about wouldn't be an issue.

[shiboujin]

fixed.

I don't mean to be a dick, I just do not understand why everyone says NV are boost friendly, besides the extra 2 PSI you could run before you need to lower the compression

First off, WOW the amount of things you guys blindly believe is INSANE!

single vanos is cake to tune. It's Just hook it up to a nos switch at X rpm and have at it. Tuning is no different.

NV motors are 10.5:1 CR while the vanos motor is 11:1 (iirc). To make the NV motor have some pep, BMW put in longer duration cams. NV motors also have the strongest (IE heaviest) rods they have ever made for an inline 6. They also have dual valve springs stock (M50tus do not).

Otherwise the motors are the same. Stock hp and tq output is almost identical on peak numbers. M50tus tend to have a higher over all curve (read: low end).



If you want my opinion on what to get? Get the motor for the easy swap. You can always fuck with it later.

I chose the NV because it was simpler to boost with less mods (lower CR, dual valve springs, thicker rods). Vanos had nothing to do with it.

[Wh33lhop]

NV CR is 10:1, TU is 10.5:1.

But yeah.

[xwill112x]

First off, WOW the amount of things you guys blindly believe is INSANE!

single vanos is cake to tune. It's Just hook it up to a nos switch at X rpm and have at it. Tuning is no different.

NV motors are 10.5:1 CR while the vanos motor is 11:1 (iirc). To make the NV motor have some pep, BMW put in longer duration cams. NV motors also have the strongest (IE heaviest) rods they have ever made for an inline 6. They also have dual valve springs stock (M50tus do not).

Otherwise the motors are the same. Stock hp and tq output is almost identical on peak numbers. M50tus tend to have a higher over all curve (read: low end).



If you want my opinion on what to get? Get the motor for the easy swap. You can always fuck with it later.

I chose the NV because it was simpler to boost with less mods (lower CR, dual valve springs, thicker rods). Vanos had nothing to do with it.

/thread

[shiboujin]

NV CR is 10:1, TU is 10.5:1.

But yeah.

ah there you go lol.

[e30polak]

Take out FI/Vanos/Vtak/whatever, custom tuning on a dyno isn't cheap, regardless of your setup.

Osh tuned my car for $300 in the GB we had. ;)

Tune is way better then the Turner one for the same mods.

He normally charges $500 NA and $1100 boosted!

[lifeiskaos]

First off, WOW the amount of things you guys blindly believe is INSANE!

+1. Danny said it best

single vanos is cake to tune. It's Just hook it up to a nos switch at X rpm and have at it. Tuning is no different.

+1

NV motors are 10.5:1 CR while the vanos motor is 11:1 (iirc). To make the NV motor have some pep, BMW put in longer duration cams. NV motors also have the strongest (IE heaviest) rods they have ever made for an inline 6. They also have dual valve springs stock (M50tus do not).

1) wh33lhop corrected your specs, but same idea
2) sure, stock nv cams might be more aggressive than vanos, but s50 cams are bolt on ;)
3) i'm not sure why heavy rods = strongest, but weight aside, the vanos m50 has longer rods (140mm vs 135mm), which put less stress on the cylinder walls, due to the rod ratio. In any case, if i had to choose a rod for a high HP engine, I'd choose an s52 rod over a nonvanos m50 rod any day
3) if dual valve springs were really better, don't you think BMW would have used them on s50's and s52's?

Otherwise the motors are the same. Stock hp and tq output is almost identical on peak numbers. M50tus tend to have a higher over all curve (read: low end).

low end = faster spool = more area under torque curve = :nice:

If you want my opinion on what to get? Get the motor for the easy swap. You can always fuck with it later.

Agreed





Like I said before, if you are keeping your engine 100% stock, meaning no thick headgasket, I can sort of understand why you'd want a NV, simply because of it's lower compression ratio. There are good arguments for each engine, and everyone will always have different opinions. I'm just tired of reading people be so quick to say "NV is more boost friendly". To be honest they're both boost friendly. Just know what you're getting into so you don't end up regretting it.

[416stroker]

single vanos is cake to tune. It's Just hook it up to a nos switch at X rpm and have at it. Tuning is no different.

Exactly

+1.

3) i'm not sure why heavy rods = strongest, but weight aside, the vanos m50 has longer rods (140mm vs 135mm), which put less stress on the cylinder walls, due to the rod ratio. In any case, if i had to choose a rod for a high HP engine, I'd choose an s52 rod over a nonvanos m50 rod any day

Just want to add on the benifits of the 140mm rod in the TU
The longer rod in the TU benefits by reducing piston speed which allows it to turn more rpm's safer. Slower piston speed generates less friction and reduces pumping losses due to better ring seal. It also allows the piston to remain at TDC and BDC longer allowing for more cylinder filling and more complete combustion. which in turn helps the TQ curve out and frees up HP.

3) if dual valve springs were really better, don't you think BMW would have used them on s50's and s52's?

S5x have conical correct? there better

[shiboujin]

1) wh33lhop corrected your specs, but same idea
2) sure, stock nv cams might be more aggressive than vanos, but s50 cams are bolt on ;)
3) i'm not sure why heavy rods = strongest, but weight aside, the vanos m50 has longer rods (140mm vs 135mm), which put less stress on the cylinder walls, due to the rod ratio. In any case, if i had to choose a rod for a high HP engine, I'd choose an s52 rod over a nonvanos m50 rod any day
3) if dual valve springs were really better, don't you think BMW would have used them on s50's and s52's?

I was talking about easiest to boost meaning you have to fuck with it as little as necessary. If you wanted an upgrade, you can run a NV with dual intake cams.

I didn't say heavy rods were strong. I said these are proven to be the strongest rods but as a result of how they did that, they are heavier. I've seen numerous bent tu rods but I have yet to see a bent NV rod. Again, you can upgrade rods but my point is drop in and go.

M50tu/S50/S52s don't use dual valve springs to keep valve train loss to a minimum. S50/S52s have stronger single valve springs. but again, you'd have to swap them into an M50tu. If you really wanted not to worry about valve float, don't fuck with newer M stuff, get some titanium single valve springs.

low end = faster spool = more area under torque curve = :nice:

You make it seem like you just proved me wrong. You also make it seem like vanos is godly. honestly, Vtec (*GASP*) is much more advanced than our single vanos. Dynos have proven that the M50tu sacrifices up high for the over all power curve. Which is why you READ and LEARN about motors before you pick one. Some people want peak power. Some want over all curves. To each his own. Don't just spew back "facts" you've heard around forums.

Like I said before, if you are keeping your engine 100% stock, meaning no thick headgasket, I can sort of understand why you'd want a NV, simply because of it's lower compression ratio. There are good arguments for each engine, and everyone will always have different opinions. I'm just tired of reading people be so quick to say "NV is more boost friendly". To be honest they're both boost friendly. Just know what you're getting into so you don't end up regretting it.

0.5:1 CR difference is a really really dumb reason to pick one motor over another for boost. Just get a thicker MLS and some ARPs. IMO M50s are more boost friendly than M50tus out of the box. If you want to drop in and boost, M50nv are easier all around. Less swap work, just slap on an MLS and some studs and go. It will take higher boost with no modifications.

Again, I'm not talking upgraded rods, cams, or getting M3 stuff. If you dropped an M50 in car A and an M50tu in car B, shoved the same CFM/boost into them, the M50tu would pop first. If you want to build a motor, there is more to look at. although the only diff there is vanos vs no vanos bs to deal with (cams mainly).

How about this, I'll post my dyno graph on my stock NV with only an mls and arp studs. Lets see what the dyno looks like with a similar setup vanos. altho I'd like to fix my cracked manifold first lol.

[lifeiskaos]

I'm done arguing about this. I said there are good arguements for both, I'm merely trying to share more info so that people aren't swayed by the "followers" that NV is the best for boost. Not trying to prove I'm right, just sharing my opinion.

[5mall5nail5]

I've been linked to this thread and want to clear some things up.

A lot of people are talking about compression ratios and cam profiles and such and have no idea what they're talking about (to put it plainly) :)

The NV is 10.0:1 because the LACK of knock sensors. The ECU is smart enough to control and adapt fuel and timing but without knock feedback its a little risky to put a 10.5:1 motor in a street car in 1992 without knock control where the fuel is 92 octane on average (think left coast).

Because both motors are 2.5L but one has 140mm rods and the other 135mm rods. In theory the longer rod ratio is preferred, there's less axial load.

Both are 24v heads, one has an adjustable intake profile. This is on or off here guys, its not PWM modulated or oil pressure driven... it's on or off. Whats not on or off about it is the conditions when it runs. It is not simply a WOT switch, or an RPM window switch. It's a confusing mess of TPS vs coolant/intake temp vs rpm vs MAF load vs.... so to say "it turns on at X and off at Y" is severely simplifying the equation.

The reason I like the NV motor is that it has/had mechanically beefier rods than the M50TU. Yes both are forged and the M50TU probably weighs a gram or two lighter, but I slept at night knowing how chunky the rods were. I also like the lack of vanos because quite honestly my turbo configuration is not really one that would notice a 10 ft lb torque bump below 4500 rom. Running a larger turbo I could care less what my power looks like at 3000 rpm. The cam profiles are different because the M50TU is able to manipulate the profile while running. It runs a more consdervative 228 deg (i believe) duration camshaft while the NV runs a 240. The M50NV is much lumpier at idle while the M50TU is much smoother. This means low RPM power and comfort are there on an M50TU and then it bumps VANOS and it can flow up top too.

It doesn't matter what you pick you can make power with both. I run Wiseco pistons and eagle rods in an M50TU block with an M52 crank with 135mm rods and a NV head. I am looking for a M50TU head only because aftermarket valvetrain parts are cheaper and more common. Some of the reasons for both sides of this argument are a little ridiculous. Yes VANOS is/can be noisy. Yes it can fail. Yes its expensive to fix and yes it can get mechanically stuck. The benefit that I've seen of running VANOS seems very very minimal. So, in my case, I did without it.

[Danny]

+1. Danny said it best

I did?

Cool.

[lifeiskaos]

Thanks Captain Bandwagon.

Yep, you did. Because that's what I think when I see people say "NV for boost"