Anyone naturally aspirated with MAP readings at WOT?

[FMOS Racing]

I'm surprised how significant the vacuum readings on my white truck are at WOT. I think practically everyone running a PxS is boosted, but I thought I'd see if there were any other NA combos lurking out there that might have a data log I could poke at.

 

[siderbox]

I could check mine.....but I just took the engine out.
I'll look back at my logs to see what I have.

 

[core-rider]

Edit: Well I checked, but all mine seem to be post turbo install. The only one I have before turbo is just an idle log.


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[slow94]

I'm surprised how significant the vacuum readings on my white truck are at WOT. I think practically everyone running a PxS is boosted, but I thought I'd see if there were any other NA combos lurking out there that might have a data log I could poke at.

Well until recently my new motor was running NA and I was basically at 0.0 vacuum at WOT. But I'm not sure my motor can be a good candidate for comparison. 427 with a big solid roller.. it only pulls like 8 inches of vacuum to begin with.

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[Raymond_B]

I'm surprised how significant the vacuum readings on my white truck are at WOT. I think practically everyone running a PxS is boosted, but I thought I'd see if there were any other NA combos lurking out there that might have a data log I could poke at.

I've got some data logs before I installed the Novi, let me see what I can find.

 

[Raymond_B]

Looked at a couple of logs, around 6000-6200RPM MAP shows 98.2-98.3 kPa WOT just before gear change.

 

[ASAP]

I’m sure I do Jeff. I’ll see what I can find. How do you want ne to send to you?


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[FMOS Racing]

It can just be a snapshot, doesn't have to be anything fancy. I'll post a graph of mine this evening.

The white truck will drop down to the low 90s at WOT, measured at the factory vacuum tree. I want to put a 70mm throttle body on it and see what it does, but don't want to throw $300+ at something that won't make a difference.

I've been pretty surprised at how low the reading is. To me, that's a significant pressure drop. Like 2 psi of boost difference.

 

[oilwell1415]

Seeing a large vacuum in the intake at WOT may or may not actually be showing a restriction. The air is moving through the intake and the air outside is stagnant. Moving air will show a pressure drop over stationary air, so if you're trying to read the intake pressure from a place where air is moving at high speed you won't get an accurate reading.

 

[Raymond_B]

It can just be a snapshot, doesn't have to be anything fancy. I'll post a graph of mine this evening.

The white truck will drop down to the low 90s at WOT, measured at the factory vacuum tree. I want to put a 70mm throttle body on it and see what it does, but don't want to throw $300+ at something that won't make a difference.

I've been pretty surprised at how low the reading is. To me, that's a significant pressure drop. Like 2 psi of boost difference.

Does this help any?

 

[FMOS Racing]

Here's mine. That peak at ~4500 RPMs happens every time. At WOT, average MAP is 93.8, high is 100.6 at that peak, low is ~90 and happens immediately following the peak.

 

[FlatOut]

i just browsed thru an old laptop thinking id have a log of basically your exact setup (TFS stage 1, stock intake. full exhaust) but the only few i have saved from before the turbo was idle or cruise stuff.

 

[FMOS Racing]

I made a few pulls this morning messing around with the intake tube, having it installed, and then removing it.

I'm currently running the stock tube and filter box with an aftermarket oiled filter, and the 460/300 "cold air" inlet next to the radiator. I was curious if the stock configuration was a restriction at the ~300 hp level.

There was a little less than 1 Kpa difference between the average tube/no tube readings over a 2nd-3rd gear pull (I aligned the pulls by RPM in Excel, not eyeballing it in MLV), which is probably within the noise, though the "no tube" pulls were the higher ones. The more fascinating thing to me is that the "hump" shifted upwards about 200 RPMs, and that was repeatable. I have no explanation at all for that. Or for the hump in general given that my readings are in the throat of the intake, and there's no tuning effect that far out from the plenum.

I just need to get busy on the turbo setup. Then none of this matters. But it's fun to dig around in the data.

I tried to draw a conclusion from the average RPMdot of a 2nd gear pull, but then realized that difference could just be the slope of the road.

 

[slow94]

I made a few pulls this morning messing around with the intake tube, having it installed, and then removing it.

I'm currently running the stock tube and filter box with an aftermarket oiled filter, and the 460/300 "cold air" inlet next to the radiator. I was curious if the stock configuration was a restriction at the ~300 hp level.

There was a little less than 1 Kpa difference between the average tube/no tube readings over a 2nd-3rd gear pull (I aligned the pulls by RPM in Excel, not eyeballing it in MLV), which is probably within the noise, though the "no tube" pulls were the higher ones. The more fascinating thing to me is that the "hump" shifted upwards about 200 RPMs, and that was repeatable. I have no explanation at all for that. Or for the hump in general given that my readings are in the throat of the intake, and there's no tuning effect that far out from the plenum.

I just need to get busy on the turbo setup. Then none of this matters. But it's fun to dig around in the data.

I tried to draw a conclusion from the average RPMdot of a 2nd gear pull, but then realized that difference could just be the slope of the road.

Turbos make it all better. Just wrapped up my twin install.

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