Alternatives to BBTB

[Colby Colbs]

No before and after dyno?

[Talperian]

The previous dyno results with the M50 manifold were not done at the same shop. Below image is the previous dyno results with M50 manifold, It's still not really relevant because he went back again after this for another revision session and was able to squeeze out 289whp (I don't know what RPM).

The change in power/torque curves I believe are still valid to compare though.

I can see that peak torque occurs ~500rpm later with the s54itb/airbox setup and doesn't taper off as fast, maintains 225wtq@7500rpm. Whereas the m50 manifold dyno is falling past 200wtq at ~7100rpm.



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[Colby Colbs]

Would be really nice to see. I wouldn't expect 40whp from a throttle body and air box change. That's more power than I measured doing cams and revving higher with a big bore TB and custom tuning with a 3.5" MAF and a full exhaust. We measured 30whp and tq. Same dyno before and after.

[NOTORIOUS VR]

Useless info/comparison really... different dyno, etc.

I don't believe ITB's and that airbox adds 40whp... sorry

[someguy2800]

Would be nice to see a true back to back, but I am going to put my money on 321whp from a mustang dyno over 289whp from a dynojet every day of the week. Every scrap of evidence I see reinforces my opinion that the M50 manifold is not nearly as good as we, or at least I, once thought it was.

[Colby Colbs]

Would be nice to see a true back to back, but I am going to put my money on 321whp from a mustang dyno over 289whp from a dynojet every day of the week. Every scrap of evidence I see reinforces my opinion that the M50 manifold is not nearly as good as we, or at least I, once thought it was.

I don't think it's that good at all, just better than a s52 manifold. I've been a huge proponent on custom forward facing intake manifolds on these cars since about 2010 for good reason. Still, from the data I've gathered, that seems lofty.

[NOTORIOUS VR]

I am going to put my money on 321whp from a mustang dyno over 289whp from a dynojet every day of the week

In my experience, that is a bad place to put money.

Every scrap of evidence I see reinforces my opinion that the M50 manifold is not nearly as good as we, or at least I, once thought it was.

Maybe so - but for the data we have right now in this thread? All seems very doubtful to me that 40whp NA is at play here.

But would like to see the comparison on one car, on the same dyno on relatively the same environmental constraints.

[someguy2800]

In my experience, that is a bad place to put money.



Maybe so - but for the data we have right now in this thread? All seems very doubtful to me that 40whp NA is at play here.

But would like to see the comparison on one car, on the same dyno on relatively the same environmental constraints.

Well its not 40, its 32. After seeing how my car reacted to my intake manifold I don't have any problem believing 30 whp on a motor that really wants the airflow.

[Talperian]

Would it be helpful to overlay a completely stock untuned z4m s54 graph from that same mustang dyno over the s52 dyno? I have that.

For the record, noone ever said 40whp. It was 30whp across two different dynos...

What's important is the shape of the curve...If you look at the graphs closely, and do some simple math and consider the fact the car is now making peak power at about 500rpm higher... the results appear highly plausible to me.

I used to think that intake/runner geometry didn't matter that much either...my opinion has been changed by data.

Notorious VR, although I agree that having the stars align and having back to back dynos under the exact same conditions is ideal. I don't think the results can be discounted that easily, if that's the case we can discount about 95% of the dyno results in any given thread on this forum.


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[GG///M3]

Would it be helpful to overlay a completely stock untuned z4m s54 graph from that same mustang dyno over the s52 dyno? I have that.

For the record, noone ever said 40whp. It was 30whp across two different dynos...

What's import is the shape of the curve...If you look at the graphs closely, and do some simple math and consider the fact the car is now making peak power at about 500rpm higher... the results appear highly plausible to me.

I used to think that intake/runner geometry didn't matter that much either...my opinion has been changed by data.

Notorious VR, although I agree that having the stars align and having back to back dynos under the exact same condition is ideal. I don't think the results can be discounted that easily, if that's the case we can discount about 95% of the dyno results in any given thread on this forum.


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That would be great

[Talperian]

That would be great

Here you go!

This is a bone stock, untuned, s54 Z4M.

Graph is cut off at 7500rpm because that is all the s52 was revved up to, owner was nervous because he still has hydraulic lifters and a stock TV damper.

Looks like the s54 is making more torque/power down low, which is to be expected.



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[someguy2800]

Dashed lines are stock S54 and solid lines are S52 with cams and your ITB's right?

[M3poseur]

It’s still quite impressive for that old technology motor to produce that kind of power in NA. I might have to rethink my s54 swap option now.

That little bit of loss down low doesn’t bother me. Look at that torque curve after that though. It hardly have any drop up to redline. Very nice.

[Talperian]

Dashed lines are stock S54 and solid lines are S52 with cams and your ITB's right?

That is correct.

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[digger]

put it on a dynojet then its a meanginful number. for sure its going to make a fair bit more power topend thats how intake manifold like that work on an engine with this spec but to do a proper overlay needs to be same type of dyno.

You hear of operators of dynocom or mustang correcting their dynos to read like a dyno jet but running an actual dynojet eliminates the possiblity of BS.

the stock Z4M is lame its nosing over/plateauing at 6000rpm

[Talperian]

put it on a dynojet then its a meanginful number. for sure its going to make a fair bit more power topend thats how intake manifold like that work on an engine with this spec but to do a proper overlay needs to be same type of dyno.

You hear of operators of dynocom or mustang correcting their dynos to read like a dyno jet but running an actual dynojet eliminates the possiblity of BS.

the stock Z4M is lame its nosing over/plateauing at 6000rpm

I will see what I can do to make that happen. More dyno results will be coming in over the next few months.

The curves are just as important to me as the numbers.





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[NOTORIOUS VR]

The curves are just as important to me as the numbers.

as long as from the same dyno sure. Not when it's a completely different dyno the curves don't mean anything.

[pbonsalb]

It makes sense to me that an engine built to make power to much higher rpm than stock would benefit from more plenum and more throttle body area. Most of us with forced induction have not invested much in building for substantially higher rpm or ITBs or bigger plenum because we can just raise the boost 2 psi to gain another 40 rwhp. Certainly for those with bigger budgets who want more power, these mods are worth considering. In contrast, for the person who is staying naturally aspirated and wants the most power possible, these mods are essential.

[5mall5nail5]

It makes sense to me that an engine built to make power to much higher rpm than stock would benefit from more plenum and more throttle body area. Most of us with forced induction have not invested much in building for substantially higher rpm or ITBs or bigger plenum because we can just raise the boost 2 psi to gain another 40 rwhp. Certainly for those with bigger budgets who want more power, these mods are worth considering. In contrast, for the person who is staying naturally aspirated and wants the most power possible, these mods are essential.

While true if we look at the big, big dogs.... the lamborghinis and such doing 2500+ hp, they all have average sized plenums and single throttles. These are builds with billet blocks and no budgets. If there were any appreciable power to be made I am sure they'd consider it, no?

[NOTORIOUS VR]

It makes sense to me that an engine built to make power to much higher rpm than stock would benefit from more plenum and more throttle body area. Most of us with forced induction have not invested much in building for substantially higher rpm or ITBs or bigger plenum because we can just raise the boost 2 psi to gain another 40 rwhp. Certainly for those with bigger budgets who want more power, these mods are worth considering. In contrast, for the person who is staying naturally aspirated and wants the most power possible, these mods are essential.

NA is a different ball game altogether - and sure while better flowing parts that work on NA builds also in theory show gains in FI there are things like intake and exhaust pulsing and cam timing differences that are not as sensitive on FI tuning then they are on NA tuning. NA tuning is just so much more sensitive to little changes and optimizations (even to the point that injection angles/timing can make or break a power band).

Most of the time there is little difference to plenum sizing, etc. on FI unless what you're starting with is already really out to lunch on specifications. There is differences when it comes to plenum shape and runner length/diameter, etc.

Most aftermarket parts are built/designed around specific use cases - not broad use cases, and they often are designed/built to resolve a specific set of criteria as well.

[digger]

While true if we look at the big, big dogs.... the lamborghinis and such doing 2500+ hp, they all have average sized plenums and single throttles. These are builds with billet blocks and no budgets. If there were any appreciable power to be made I am sure they'd consider it, no?

its nothing to with single throttle butterfly size. it is runner diameter, length and taper and to a lesser extent plenum size / shape

[Talperian]

its nothing to with single throttle butterfly size. it is runner diameter, length and taper and to a lesser extent plenum size / shape

This!

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[someguy2800]

Yes, the runner is where all the magic happens. The plenum is just to get the air to the runner. Once the throttle is wide open the plenum is just an extension of the charge pipe (or atmosphere for an NA engine). If the throttle is properly sized then there is no difference in air pressure before and after the throttle once its wide open so there is no boundary or divider between them anymore and they are part of the same volume. Once the throttle is wide open then everything from the intake runner opening to intercooler core is now the plenum. If there is any restriction along that space that causes a pressure drop such as a sharp bend or other restriction, then that point is now the throttle. On a turbo car you could argue that once the manifold throttle is wide open, the compressor wheel is now the throttle since it is the gate keeper of the air.

[Def]

Plenum size does matter on all ICEs. It's not just a static chamber of air, it couples with each runner to determine how the resonant response of the airflow to each cylinder responds in the time domain. Think of it as acting somewhat like the mass in a mass-spring-damper 2nd order mechanical system.

That said, as people have pointed out, it isn't usually that noticeable on the behavior/power curve of a turbo engine because the power curve is usually dominated by things like intake/exhaust pressure ratios that are a much larger effect. You really notice the difference of having an additional 0.5 psi at the intake valve in a certain RPM range on an NA engine, but on a turbo engine that has an EBP/E-MAP of 25 psig while you're running 15 psig of boost - it's almost in the noise at that point.

[NOTORIOUS VR]

On a turbo car you could argue that once the manifold throttle is wide open, the compressor wheel is now the throttle since it is the gate keeper of the air.

I could see that becoming a meme