So this got me thinking. I am running larger intake tubing so there is less of a vac in the intake tract. Since the roots has the bypass valve that opens under vac, that means that it won't be opening as often. So I loose mileage on the highway, but have a more responsive blower.

 

You won't necessarily lose mileage as the engine is working less.

autospeed.com has a whole series of articles on airbox modifications.

 

You must look at it differently as you are mixing to different throttle states.

The engine is creating a vacuum when its turning, which is why when you have the throttle almost closed (so idle/cruising), there is a big vacuum behind (so between the throttle and cylinders). That opens the bypass valve, and lets the sc work less.

When you open up the throttle, so at wot, there is an open passage from the air filter until the engine (with the sc in between of course). If you have then any vacuum (especially after the tb and before the sc), it shows that the intake isn't efficient enough to fill the intake fast enough with air.

By spinning the sc faster, it will consume more power from the engine, so you will lose some economy, but can't tell how much on an eaton system.

 

So you got a larger intake to replace the one in the photo you posted earlier? What diameter is it now?

 

Well I am starting to piece together my 92mm MAF with my 4" tubing so I was test fitting some pieces and it got me to think about it.

 

Why are you using 4" tubing? I would think you are causing a bottleneck.

 

I assume by bottleneck you mean restriction.

The air is being sucked in, not blown in to the TB, which is the current restriction, so as long as the MAF can accurately meter the air, you cannot go too big before the TB.

It has been proven that a 3.5" intake tube yields substantial (15++ HP) over the stock 2.95" intake tube. The 4' ought to yield some additional benefit, especially given many of us are running pulleys and other mods which increase overall air volume flow.

I have attached a photo of my current intake vs the stock one.

92mm MAF vs 75
4" intake tube vs 2.95
4" to 3.5" 90 degree bend to 3.5 tube to 3.5" smooth sweep 90 degree bend into my now 82mm (3.25") TB

When I get my car back on the road in approx 2 weeks, I can tell you how much vacuum has been eliminated with my new intake vs the stock one by seeing the difference in my boost gauge. I will post again when I have that info

Which do you think will flow better?

 

To follow up, I saw a +2 lbs of boost increase with my larger MAF and intake with the same TB. This proves I reduced 2 lbs of vacuum in the intake at WOT. So all those who said I must have had zero vacuum in the intake and was wasting my time and had no clue what I was doing are hereby proven incorrect through this on video demonstration. I was using the same gauge with the same 82mm Maxbored TB. The video below was with a passenger in the car, and the trunk full of stuff, so probably 300 lbs over racing weight.

The 16 psi can be seen in my video of my 0-100 mph run which can be seen here:
Yes I know some people are annoyed that I provide and demand video proof as proof, but to reduce the amount of pontificating of who is correct or not, I'm raising the bar of evidence to something that is more difficult to fake or take out of context from some one else's car.

When I added the water/meth injection when injecting before the blower, I got +1 additional pound of boost, +2+1= a gain of 3 lbs over the stock setup.

I am consistently seeing 15-16 psi max boost. This is with a stock upper pulley, + 4 lb lower pulley, Steig ported 5th gen Eaton, and running water injection BEFORE the blower.

I like it. The car is A LOT faster, I can definitely feel the improvement with the extra 6-7 psi of boost over stock.

I've seen postings on this board saying the lower pulley will only give 15 hp. Simply not true. I've also seen it taken as gospel on this board that the boost will fall off at higher rpms, or that Eatons are already so inefficient they are maxed out stock, that if you add a pulley you will run too hot etc. That is all B.S. as proven by watching my boost gauge keep climbing to redline. This video was after 4 other runs trying to get better lighting, so after 4 back to back runs, if heat soak was a problem, then my car must actually be faster than this

When I added just the lower pulley with the stock intake, it was much faster than 15 hp could give. Then when I added this intake I and muppet labs designed and built, it is much much faster. When I get my dyno done I will get them to overlay the power curves on the same paper as my last car as a direct comparison.

Boost Gauge reading:
9-10 Stock pulleys and intake with maxbored TB
13 with lower pulley installed = a gain of 3.5 to 4 psi as advertised
15 with 92mm MAF/ muppet labs intake and high flow cats
16 as above + Water injection 375 ml/min injecting before the TB gives +1 additional lb of boost on the gauge
17 I briefly saw 17 psi when the temp was just about 68-70 degrees F out, so colder/denser air gave a little more boost

 

Yes, I added video proof.

 

I agree with your comments about the boost. When I had a ported Eaton with both upper & lowers pulleys & Snow water meth on a very cold day I saw just over 21psi of boost. I decided to leave the meth off in the very cold weather.

I spoke with Chris @ Pro M about the larger intake going into 90mm throttle & he said NO. You are running a smaller setup than I have so I still think it is a bottleneck. You are further restricted by the design of the Eaton intake that Jaguar uses. I think you may also be confusing the zero vacuum @ wide open throttle. The way it was explained to me is that you would have to tap in where the MAP sensor is to take the measurement. You are seeing similar results to what I saw when using the Eaton including the water meth raising the boost.

 

Just for clarification, I was not referring to you as being one of the people who said there was no vacuum in my intake track.

Your question was that the 82mm TB is the bottleneck of my system, and is a restriction, which is correct.

You running the water injection before the blower was the first time I had seen it done on our cars, so I simply copied you.

The point I was making in my post was that I was told that I had no vacuum in my intake to begin with and that going to a 4" to 3.5" would yield no benefit.

This is what I have proven false as I clearly have gained +2 lbs by using my intake design.

My response to your bottleneck question was that going larger before the TB was a benefit as shown by my results.

I am not convinced Chris at ProM really knows what he is talking about as he told me that unquestionably he could calibrate his drop in MAF sensor into the system I sent him emailed photos of, but then after I paid for it and mailed the intake to him, he told me he could not, and STILL refused to refund me for the un used drop in MAF sensor which he recommended to me, then he also had no clue about the IAT sensor and said theirs worked fine, which it obviously did not. So he has very little credibility from my experience.

I am happy so far with my 92mm MAF I bought from them, just not happy they have zero integrity of admitting mistakes or ignorance and still sticking me with the bill. He should have taken the return and credited it toward the 92mm MAF rather than just keeping all the $.
Like I said, zero integrity in his business dealings with me= no credibility that he knows at all what he is talking about, either he was trying to scam me, or he was talking out his *** and did not know it.

 

I just installed a vdo boost gauge but it only shows me 11psi and doesn't go any higher. I plumed it to the port that is on the plate right above the s/c (that feeds both aftercoolers). Now I didn't have a true "T" to use, as mine looks more like a "F" I am thinking that might be a part of my problem, but I am not 100% sure.

 

Do you have a pulley? My car stock showed approx 9.5 psi. The 4.2s have stock a larger lower pulley and thus have more stock boost than the 4.0s do.

I don't think it makes any difference if you use a t or y or "f" .

 

Yup, eurotoys pulley 1.5 pulley. Stock STRs should be at 13psi

 

I am totally not familiar with the STRs. Have you seen any other STRs at 13? Or is that just per the info given from Eurotoys?

I have yet to hear of any 4.0 XJR stock running over 10 psi, even though they are "supposed" to be 11.6 psi. The 4.2s with the larger lower, yes, but not the 4.0s.