This is how you measure exh manifold pressure.

[Michael@FP]

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This should improve the signal quality of my exh manifold pressure channel on the M800 without electronic signal conditioning! Running 4 taps into a damper chamber with the sensor instead of only one in the collector is a def improvement in data acquisition!

 

[Archer Fabrications]

Is this supposed to be similar to calculating boost? Or just pressure post CC? Whats the benefit here and what would you use the data for? Just to pick your brain.

 

[Black95TSIawd]

Looks sweet!

Correct me if i'm wrong, but thats not your standard FP race DSM manifold, is it? Evo perhaps?

 

[Archer Fabrications]

Looks like it to me?

 

[LandSpeed-DSM]

Research "turbine drive pressure" Kyle. It's a useful bit of information. I measure it as well as several others here.

 

[Archer Fabrications]

Googling now

Edit:
Ahhhh
In general terms, low drive pressures are preferable to high drive pressures (and associated higher EGT's). If the turbocharger turbine and compressor are more efficient, less drive pressure (actually, exhaust gas horsepower, or EGHP) is required to produce a given amount of airflow at a given compressor head (compressor discharge pressure minus compressor suction or inlet pressure). The lower the drive pressure for a given boost, the more efficient scavenging will be during valve overlap as well - ideally, drive pressure should be less than boost pressure, but that won't always be the case if the turbocharger is operating far off the best efficiency island on its map.
Source:http://www.dieseltruckresource.com/dev/turbo-drive-pressures-t47179.html

But what do you do with the data once you have it? Change a larger turbine housing if DP is too high?

 

[Boostdriven]

I've been logging drive pressure for years now, its one way of telling how hard you're pushing ## turbo to make boost at high rpms.

 

[Boostdriven]

But what do you do with the data once you have it? Change a larger turbine housing if DP is too high?

If you like faster spool up and lower end torque then smaller housing is the way to go but the down fall of it is that you will loose power in the higher rpms. The way I look at it is this, if you build an engine to rev to 8500 rpms and plan on reving it that high on regular basis then you want all the supporting mods to be able to make peak power at about 7800-8000 rpms. But if you rev to 8500 rpms and your engine is making peak power at 6500-7000 rpms then you're just wasting you motor unnecessarily

 

[Archer Fabrications]

I know the general benefits/down sides to larger/smaller housings, i was referring to, what do you do with the data once you habe it and your already on a brand new setup? Do you just start changing out parts? Or can you use this data to degree cams or aid in tuning?

 

[Greedy Pimp]

Looks sweet!

Correct me if i'm wrong, but thats not your standard FP race DSM manifold, is it? Evo perhaps?

Would like to know also, not on the website.

 

[Archer Fabrications]

Looks to me like a normal manifold that he modded, like anyone could drill 4 holes in the flange...

 

[LandSpeed-DSM]

I know the general benefits/down sides to larger/smaller housings, i was referring to, what do you do with the data once you habe it and your already on a brand new setup? Do you just start changing out parts? Or can you use this data to degree cams or aid in tuning?

Not to hijack Michael's thread too bad -

It's contextual. But you are on the right path with regards to housing/wheel sizing as well as cam spec and phasing.

I've measured it on a previous setup where the only major bits changed were the turbine housing and manifold, for example. Manifold changes were required because I went from Bolt-on to Open T3 to Divided T3 to Divided T4. Sometimes the results were counter-intuitive when you hit on a setup that compliments its self well the whole way through. Like the big T4 housing/manifold spooling as fast as the T3 setups but making more power over a wider rev-range at the same boost level.

Very general overview here while I'm on my break, from a phone so bear with me a bit:

Traditional turbo cams were/are made with little to no IO/EC overlap because of the pressure differential between the exhaust manifold and the intake manifold. This contaminated the charge, hurt VE because the incoming charge is now fighting the exhaust reversion, etc.

While different Boost/Drive ratios can tell you a lot about a setup when taken as part of a larger picture in terms of camshaft choice/phasing you can cam the car more like an NA with Boost/Drive near 1:1, or even like that of a Supercharged engine when Boost is Greater than drive though this is either uncommon or not talked about for competitive reasons.. I'll let you speculate.

Also consider these values (MAP vs. EMP) are not in a fixed relation ship, as the turbo accelerates from rest they will intersect on a gasoline application usually at least once.

It can tell you how efficient your setup is, it can suggest a bottle neck or non-ideal cam timing. You can not only change spool with cam timing adjustment, but drive pressure. If you take exhaust system back-pressure as well it can further help track down an issue or a place for improvement.

Some setups regulate wastegating based on drive pressure. I want to say Kevin Jewer has tried or currently employs this method.

There are myriad reasons for monitoring your drive pressure, but by its self it may not be especially helpful. You should make more power/psi boost if you decrease drive pressure.

 

[Boostdriven]

I've tested a number of different housings on my HX40 while logging drive pressure but I did it just for my owe information. Even though drive pressure is kind of a given number for each given housing but different data from different housings will give you a better understand of what housing does what which makes choosing a turbo for a particular setup easier.

Peak HP is determined by the efficiency of air going in and out of the engine. Logging drive pressure give you data so you can determined if peak HP is related to drive pressure or something else like cams or intake manifold. For someone who is just going to buy one turbo for a given setup and plans on running it for a long time then logging drive pressure is probably useless to them, its nothing more then just another gauge. But if you plan on experimenting with different turbos/housings then it could be a very useful piece of data, that's just my opinion.

 

[Greedy Pimp]

Looks to me like a normal manifold that he modded, like anyone could drill 4 holes in the flange...

Look closer, the exhaust manifold outlet is on the right side and seems to be twin scrool, so I would assume this is a new Evo manifold?

 

[synthetek]

Looks to me like a normal manifold that he modded, like anyone could drill 4 holes in the flange...

Turbo flange looks different, runners look different, looks like it has holes to bolt on a heat shield too.

 

[JFZERO ECLIPSE]

On the heat shield idea..... They couldn't consider that for those of us that have their manifolds?

I would die to have the factory manifold cover on

 

[bastarddsm]

I've seen setups like this, read wrong, the flow by the orifice can actually draw a vacuum on it.

 

[LandSpeed-DSM]

I love how everyone is speculating over the manifold

 

[bastarddsm]

That's not a dsm head or manifold!!!!!! I win!

 

[99gst_racer]

Very clean install. I wouldn't have ever thought to go through the flange like that.

This should improve the signal quality of my exh manifold pressure channel on the M800 without electronic signal conditioning! Running 4 taps into a damper chamber with the sensor instead of only one in the collector is a def improvement in data acquisition!

I'd love to see a before and after difference of the data that you gather. Meaning this configuration vs. from a single point on the manifold.

 

[tstkl]

I've seen setups like this, read wrong, the flow by the orifice can actually draw a vacuum on it.

I can't tell what type of fittings those are (look like swagelok compression), but its very possible he has a "pitot tube" extension in there to avoid this phenomenon, however I doubt it. This would cause other issues (inertia) and similar inaccurate readings.

With his set up he will have only one signal firing at a time, allowing pressure equalization from the other 3 cylinders. I would imagine closer to the collector would be more accurate. Realistically whenever you have a flow field, you have a pressure distribution, so the entire exhaust manifold is not at one pressure anyways.

 

[fallenauthority]

I can't tell what type of fittings those are (look like swagelok compression), but its very possible he has a "pitot tube" extension in there to avoid this phenomenon, however I doubt it. This would cause other issues (inertia) and similar inaccurate readings.

With his set up he will have only one signal firing at a time, allowing pressure equalization from the other 3 cylinders. I would imagine closer to the collector would be more accurate. Realistically whenever you have a flow field, you have a pressure distribution, so the entire exhaust manifold is not at one pressure anyways.

Agreed, I would think you would want to measure closest to the actual pressure head(right in the collector before the turbine wheel).

 

[Michael@FP]

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Here it is installed.

-Michael

Sorry don't have much time to comment on the technical aspects maybe this weekend.

 

[turbosax2]

Yup, definitely jealous that the stock heat shield bolts up. Wish the DSM manifold had that option!

 

[ViciousLord]

I recognize that bay