How does that make any sense whatsoever?
How are you going to measure turbo efficency (which is what you're trying to do with a DP gauge) with an inaccurate reading of what the turbo is putting out?
drive pressure
- Thread starter 06dmax
- Start date
How does that make any sense whatsoever?
How are you going to measure turbo efficency (which is what you're trying to do with a DP gauge) with an inaccurate reading of what the turbo is putting out?
Why? all thats really going to tell you is how well your CAC and plumbing is working. If you were running a gasser and had to keep the AFR's in check I would agree with you but that doesn't really matter on a diesel...at least not the variation between the compressor and manifold..unless you've got a serious problem
I don't have a DP gauge tapped in yet...
Totally agree with Harbin. Who cares about .10 of a difference in "turbo efficency reading?? AFR is what you should care about. If you asked for 30# boost and you only got 17# would you be happy because your more worried about "drive pressure/boost ratio??
My s366 stays pretty close to a 1 to 1 at 35ish psi until it gets above 3500rpms.. by 3800 rpms it is somewhere around 33psi / 45psi drive pressure iirc. But I'm only running a 2400-2450ish pulse tune (same tune that went 12.61... I also run some meth/water inj)
If you're not concerned about efficency then why are you monitering DP? I thought that is what this thread was about lol. If you're loosing 13psi in the intake tract then I think you're got a bigger issue then efficency. If you want to minimize your DP:BP ratio then you need to moniter your turbo's performance as accurately as possible and thats not the case when you're reading boost at the minifold/y-bridge.
Why should I care about AFR in relation to boost at the manifold? If i see issues with EGT or excessive smoke then I've got a pretty good idea I'm running a little rich. If I can't get it spooled then I'm probably a little on the lean side (or way rich but that will be obvious with the exhaust). Again if this were a Gasser I would agree with you 100% that MAP readings at the manifold are very important.
Thats a seriously quick time for 2400 pulse on stock sticks
Last edited:
I don't know how much more to explain. I want to know how much pressure is actually getting to the engine and how much pressure is coming out. It is not just a turbo efficiency thing for me. It is the total efficiency thing. Might be wrong, but it seems to be working great. :thumb:
I only monitered it for a day to test something. I'm also not loosing 13psi, I just used that as an example. Because you made sound like it wouldn't be a big deal to not acheive good boost aslong as you have a good boost/ drive ratio. I was agreeing that I care about my engine is getting the air pressure it asked for in the tune more than a perfectly efficent turbo. Its a stock turbo, get a aftermarket fixed geometry one if you want great ratios. P.S. I run less pulse than both of you
But what are you gaining realisticaly by reading at the manifold and not the compressor?
Sorry not trying to be a dick just realized I came off that way a little. I'm just generally interested in your train of thought..maybe there's something I didn't realize or think about.
Ben, but you can do that logging at the compressor... it's not going to be a very large difference unless you have a leak or blockage. Most trucks resort to the max vane table on big tunes anyway becuase the stock map doesn't read high enough...at least from what i've seen on most lb7/llys
Ben, but you can do that logging at the compressor... it's not going to be a very large difference unless you have a leak or blockage. Most trucks resort to the max vane table on big tunes anyway becuase the stock map doesn't read high enough...at least from what i've seen on most lb7/llys
With it in the y bridge, I know how much pressure is actually entering the engine so i can monitor how efficient the thing is as a whole not just my little charger. That is how and why I want it in the bridge. I could probably get more technical but the boost "should" be higher at the charger so it would improve my dp vs boost numbers anyways.
What does it matter? Their might be a 2-3 psi difference in numbers between pre and post intercooler. If all you're trying to do is establish a drive pressure to boost ratio the unaccounted variables would have more effect on the numbers than the 2-3 psi difference.
My gauge is tapped into the y bridge. Why? Because I can't tap a gauge into a rubber boot.
My gauge is tapped into the y bridge. Why? Because I can't tap a gauge into a rubber boot.
Thanks! The thing is, that's at high rpm... I increase pulse as rpms increase... all about top end power and low torque to keep the stock trans alive. so 2400+ at 3750 (where I set it to shift) is throwing some fuel at it, also the meth adds a little fuel too....
I tried to weight my truck when I was there, but the scale at Bandimere only goes to 5k I was told... I think my truck is fairly light as well.
Ultimately, your looking at the whole system. Manifold pressure takes into account everything, and is where I am tapped. Both on the exhaust and the intake.
If you want to look at the just the turbo, I would tap the top of the up pipes on the exhaust and the outlet on the turbo.
If you want to look at the just the turbo, I would tap the top of the up pipes on the exhaust and the outlet on the turbo.