blown 944

Thought I'd post my results for those who are interested in how the Lightning MAF reacts using a straight 4" pipe rather than the 3" reducer pipe. If you all can recollect , there was some discussion in the "C-tune" thread about how using a sharp recucer from the MAF to the turbo may cause some voltage alteration due to the airflow being distorted.

So I made a 4" MAF pipe to test this out. Josh had mentioned it and he was absolutely correct (as usual ). There is a difference. With my old setup (Lightning MAF-reduced to 3" pipe then expanded back to my 4" turbo opening) I was seeing voltages of 4.7 plus out of my MAF sensor, it was not super smooth and occasionally spike even higher.

Now I am setup with a straight through 4" pipe without any reduction and at the same boost levels I am seeing a max of 4.5v and it is super smooth.

So the results are in and Josh once again had a great idea!!!

toddk911

It is annoying how he is always right, right??? Lol. Josh kicks ***!!!!

Actually, after that discussion on the other thread I was also looking at piping to do the same. Although my turbo is 3" so I was looking to do a gradual 4" down to 3" and also maybe scrap the lightning housing and re install in the new piping but I was going to check with Josh to see how re installing the sensor might have any ill effects.

So with 4.5v you were right about our set ups as that puts you and I almost spot on the same MAF v readings as I see about 4.4-4.5. That is of course unless my piping is causing higher readings also. I go from the MAF to a 3.5" to 3" coupler to 3" elbow right to 3" turbo inlet so not really drastic. Because technically 90mm is only about 3.5 inches.

Do you/Josh think it is the sharp changes in piping diameters causing the erroneously high readings or just from going from 4" to 3" and back to 4" in your situation?

blown 944

I think it was the sharp transition. I don't think that it had anything to do with opening back up to 4". The turbo pulls most of it's air through the compressor wheel rather than the surge openings.

CyCloNe!

VERY NICE!

toddk911

What is the diam of that IC pipe?

95ONE

Todd, it looks like 3" to me!

blown 944

It is 3", maYbe overkill, but at some point I plan on having 3" all the way through after the turbo outlet. Hopefully soon if I'd get off my a$$ and install the big IC...

Next up though, is to measure the exhaust pressure after the downpipe and then make a 4" exhaust. I have everything to do it now so hopefully soon.

toddk911

It's like you are in my head. lol

I have some 3" right now and couplers ready to go in but I wasn't sure it would help much going 3" and then back into stock IC inlets and then back out to 3".

Your thoughts?

I also need to reduce backpressure but was thinking more with the cut out vs. full time 4" but still on the fence.

blown 944

Todd, I don't think it makes any difference if the stock IC is used. I just did it b/c I had some crap laying around (yes crap and it looks the part, this is for you Bruce ) and it didn't seem to slow spoolup so I left it. I was also tired of having to find the pieces to adapt from a larger turbo to the stock IC pipe. I will start over again with new material, when I get around to the larger IC install.

I suppose what I could do, is to take an airflow reading with my current stuff and then (if I have the parts) throw on stock pieces and see if there is any differnce. I seriously doubt it though.

blown 944

in regard to the exhaust, I'm actually thinking just the opposite as you regarding my exhaust. I want to tie my WG back in and I'm going to add in a bullett muffler to quiet it down even further. Having a cutout is only in the works for my gold car if that.

toddk911

After seeing how crazy the backpressure goes up (50-60psi!!) with higher boost I really wanted to open up my exhaust as well. I still have stock DP and then 3" from cat back with wg dump.

Scott H

How much of that pressure is due to the KKK hotside? I thought I remember reading that the KKK hotside was crap and that even a T3 would flow better.

Paulyy

Reason why im going with a gt30r/Tial hot housing route, but yes the kkk to suffer in alot of back pressure.


you could always put a muffler on the wastegate and have it dumped. i've been thinking of dumping mine at the back with the 2" pipe i've got laying around.

cutouts i've read tend to leak after a while.

blown 944

Pauly I have thought about that. I'm not sure at this point which way I'll go. Right now I want to focus on the main exhaust.

In regards to the KKK super 75. I'll never understand why a P trim wheel would be a good idea stuffed into an 8 hs. By what I have read it hits 1 bar at just below what I was using a .58 t4 hotside. I had logged 1 bar at 3700 rpm.

Now if it were me and I were thinking about keeping that setup I may be prone to look at a 44mm wg and even then, you would have to rework the crossover to wg pipe due to teh weld inside only being 40mm or less. Also I think that you would be boost limited.

With all that said it probably doesn't feel too bad at sea level. Up here though it sucked to have that much lag. I till have what most would consider a large, laggy turbo, but honestly it feels pretty good considering so who knows.

86 951 Driver

Why dump the wastegate? Does it free up any HP?