DC's 1756VK-assisted B4

this mite help

http://www.verociousmotorsports.com/Shop-by-Category/Reducers-and-Transitions/Buttweld-Concentric-Reducers

Woolf has cones and transitions

http://catalog.woolfaircraft.com/ke...refer=http://www.woolfaircraft.com/index.html

Hi, Michael.
I think the most conservative approach is to mark the areas of the pipe that are too close to the firewall and, after removing the pipe, flatten it for more clearance by tapping with a nice heavy hammer.
I don't think you will reduce flow enough to matter and you'll keep the pipe that is working for you. Best of all, it's free!

Fix_Until_Broke said:

Woolf has cones and transitions

http://catalog.woolfaircraft.com/ke...refer=http://www.woolfaircraft.com/index.html

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From what I understand, stainless requires tig welding whereas aluminized doesn't. As such I have to use all ss or not and tig is more expensive. If the cones only come in ss, then I guess I'll have to go that route.

Digital Corpus said:

From what I understand, stainless requires tig welding whereas aluminized doesn't. As such I have to use all ss or not and tig is more expensive. If the cones only come in ss, then I guess I'll have to go that route.

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Stainless doesn't have to be TIG welded. You can always just use stainless wire with a MIG if you want it to be clean, but you can still use the regular wire. You can weld mild and stainless together, etc.

They have them in carbon steel as well and Mike is right, you can wire weld the two materials together, no problem.

Well if I were to do an DP with a 4" expansion chamber, I'm looking at needing at least 2 cones, though maybe 3, and I'll use 50% of their material. At a minimum price of $15-$20, I'm wondering if there is a less expensive choice. I have to ignore verocious MS cones because they seem too long at too gradual of a taper to fit in the space I need.

Right now, I will for sure be making up a 2.5" DP. I'll be setting it up with v-band clamps and will route it in the same path as I would the theoretical one above. If I decide to make the evac dp, then I'll have a base to work from. I'll have a short pipe with ~30˚ bend come off the dp flange and use a cone to expand up to the vband connector. I have dimensions of the parts so I measure things out to see if this length is fine and doesn't cut into the space to have the DP bend towards the engine and down to the ground.

I'll make it as gradual as possible paying attention to centerline radii to see if I can do a more gradual bend initially off the turbo and then tighter to maneuver past the firewall to the rest of the exhaust.

I'm aware that the idea of that evac chambered DP may not do anything significant for the setup relative to a straight up 2.5" exhaust, but curiosity beckons and someone has to spend some money (I'd dyno both) to see what gain, if any, there would be.

The general theory is that it'll aid in turbo spool-up and also lower EGTs.

I can make you some cones that are tight and ship with the DP flanges, although i'd like to see what the expansion chamber actually does when we are forcing the air in and out of the engine.

Digital Corpus said:

I'm aware that the idea of that evac chambered DP may not do anything significant for the setup relative to a straight up 2.5" exhaust, but curiosity beckons and someone has to spend some money (I'd dyno both) to see what gain, if any, there would be.

The general theory is that it'll aid in turbo spool-up and also lower EGTs.

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Michael, Look at how "repeatable" back to back dyno runs are. It is not at all clear to me the dyno will actually be able to show a small delta results from anything but margin of error from the test itself. Does this make some sense?

flee said:

Hi, Michael.
I think the most conservative approach is to mark the areas of the pipe that are too close to the firewall and, after removing the pipe, flatten it for more clearance by tapping with a nice heavy hammer.
I don't think you will reduce flow enough to matter and you'll keep the pipe that is working for you. Best of all, it's free!

Click to expand...

+1 The guy who built my motor in the Impala worked for JBA (makes headers among other things) and they tested out "dimples" on headers. He said as long as they were minor, they didn't make a difference in power. The exhause gas would slow down at the "dimple" and as soon as it passed it, the gas sped up which increased scavenging.

john.jackson9213 said:

Michael, Look at how "repeatable" back to back dyno runs are. It is not at all clear to me the dyno will actually be able to show a small delta results from anything but margin of error from the test itself. Does this make some sense?

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John, On that dyno when I was stock, there was less than a 1 hp difference between the runs. I'll have IAT & EGT gauges installed before putting this on a dyno. Doing 3 runs each with this DP, a 2.5" and possibly a final expansion chambered one with all of that data would still be significant. We've had 3 dyno days over a year and a half almost and our numbers haven't really changed so I think we'll be good.

ryanp said:

I can make you some cones that are tight and ship with the DP flanges, although i'd like to see what the expansion chamber actually does when we are forcing the air in and out of the engine.

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This is why the idea is still on the docket in my head. I'll let everyone know if/when I decide to put any money down to buy the parts.

Got Bearings? said:

+1 The guy who built my motor in the Impala worked for JBA (makes headers among other things) and they tested out "dimples" on headers. He said as long as they were minor, they didn't make a difference in power. The exhause gas would slow down at the "dimple" and as soon as it passed it, the gas sped up which increased scavenging.

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Unfortunately, the spacing issue we have is well beyond a even a 1/2" variance that we could create with a hammer. I had another look at it with Greg last night. Looks like his memory was better than mine; even from my photos for where it's hitting the firewall they aren't quite clear. If I were to just use that existing prototype and modify it, I'd cut it off the flange and re-weld it at rotated angle bringing the bottom back about 4-5 inches.

The big adjustment is that I'd have to cut off the 3"-90˚ bend at the bottom. Then cut off, this being purely guess work until I remove it, about 4 or so inches of the original tuned pipe to raise where the 3"-90˚ bend is to clear the power steering rack. Weld on a transition cone, then weld on the bend. The bend would be rotated and have another, say 30˚, welded to it and then I can hook up the rest of the exhaust. Granted, this is just an idea and nothing is finalized right now.

Some minor updates and news.

First full tank of 942.1 miles and 19.612 gallons on B20. Mixed driving with logs, freeway of 60-70 mph, et al. I'm fairly pleased with a solid 48 mpg. I've been dealing with a possible bad N75 that is affected by temperature. When it's below a warm-to-the-touch temp, it operates with near full Duty Cycle when requested. Without the boost valve, I hit 36 PSI. However, if I let the car sit for 20-30 min and then drive it, the DC is lowered about 30% across the board. I have not had the time and patience beyond my initial test to confirm for certain it is the N75, but that it on the docket for when I wake up.

I had donated my boost valve to my sister-in-law's car and a inexpensive safety solution to make sure the turbo stays within an appropriate pressure range. I know it's treating the solution and not the problem, but it'll bide time until they can afford a new turbo (turbine requires more than average force to spin via finger).

Tonight I tapped a new aluminum pipe with a fitting for the replacement boost valve and put it in to replace one of the IC pipes we jerry rigged. This brought the pipe alignments to within about 1/2" of where they had previously been located during stock configuration. With the pressure of a moderate handshake grip and a bolt+nut combo from Greg, the pipes are now solid and secure.

With the boost valve in place, I've dialed it to a half turn under 30 psi. Call me paranoid due to the first turbo incident and the fact that I'm requesting more than 2x the horse power than stock which takes a little while to get used to. I'll work out where exactly the valve is set to limit pressure too. With Greg's help, I did a plot every 2 psi, from 6 to 30, to see where MityVac's gauge, the hardware store gauge, and my tune registers boost. Having a second hand helped speed this process.

In the accurate range of the hardware store gauge I have in the car, I'm reading a solid and consistent 1 psi over what MityVac's gauge readout. The gauge is properly vented to atmosphere. Which of the two is the more accurate?

Anyhow, I'll pull a proper log with my actuator now set to 4.5 inHg start and a touch over 17 inHg for full range and see how it performs. Exhaust work has been delayed for at least a week.

Michael,

Each gauge is off by one half a pound. <bg> Seriously, I would consider the higher reading to be the correct reading and tune with that in mind. It is the safer choice. Besides, one psi will not make much difference. The good news is that each gauge is in close agreement to the other.

Post #3 updated with photos of Exhaust Manifold after being prepped to paint. Shiny

PS - I had barely started marking material to remove to port the outlet at this stage.

Bump for preview
I'll post install photos soon. Need to heat it up and clean up a bit.

So the new down pipe is on and after having it welded up and cleaning it up a bit, I pulled a log on a new tune to test it with. Due to the end of the down pipe being too wide, I looked up a table of thermal expansion coefficients and ran some numbers. After heating up the steel v-band collar to about 450˚F and cooling the end of the pipe with some dry ice (perfect excuse to have fun, no?? ), I was able to slip the flange over. Had to hit it a few times, and then nudge things around with a hammer to make it flush with the end but hey, it worked

I had a last minute change when I was test fitting pieces and after considering the size requirements if I were to make a 4" expansion chamber, I changed the short pipe coming out of the flange from a straight piece to a section of a 45˚ elbow to do it instead. I'd still have to make a bit of a corkscrew in order for it to fit, but I think it's doable. I think I'll toss in the old tune in and pull a log to see if there is a discernible difference between the two logs.

Oh, and here is an audio clip of the engine starting with the pipe. Careful, it might be loud

To quiet. Lol.

Digital Corpus said:

I think I'll toss in the old tune in and pull a log to see if there is a discernible difference between the two logs.

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By "old tune", do you mean the tune you ran on the dyno in December?

Not quite. The one after that I happen to pull logs with on a specific stretch of road. However, that one I could test between too.

Question for those who've been following:

How should I approach high IATs?

My aim with all of the modifications though, is to work smart and not hard. There is a correlation between IATs and EGTs. I haven't installed a gauge to read the EGT probe that is installed partially due to laziness (sorry!) but mostly due to the fact that I'm just cruising the highway to and from work. Plus, I do plan on setting up a DAQ system and I prefer to do things all at once; i.e. I don't want to buy a set of gauges now just to replace them later.

Since an IC is a heatsink, it takes a while to bring it up to its nominal temperature. On a night of ~7C, with IATs hovering at ~19-21C, I will peak at ~32C and it'll fall off shortly. However, I've been driving the highway for 20 minutes of so, pulled off for about 5 min, then went back onto the highway and was able to peak it at ~40C. BTW this is all with my tune setup at about 29 psi (boost-valve-controlled tune if you will).

My options seem to be this from reading the forums:
1) A FMIC is the defacto solution.
2) A water injection system triggered from the IP's 5v signal (thanks JFettig for the tip!), which is inherently dependent upon load and RPM, as well as the IAT sensor.
3) Replace the stock IC with a newer, but more efficient aftermarket one (I swore someone has done this already, just have to search for that thread...) in order to maintain stock piping, but also install a water injection system.

Maybe an air to water intercooler setup? It can be mounted anywhere and make the piping from the turbo to the intake manifold shorter.

DC

You want to cool the peak temperatures, right. You are not worried about air or EGT temps in normal operations. The best way to reduce peak operating temperatures is with water injection. Water can soak up a vast amount of heat when you really need it at high boost pressures. Since you are running 25+ psi at peak boost with no bottom end upgrades and want to put off a full engine rebuild as long as possible. My suggestion - start with EGT temp monitoring so you know the baseline, then add H20 injection. Up grade the intercooler later if you need it.

SuperAdellic said:

Maybe an air to water intercooler setup? It can be mounted anywhere and make the piping from the turbo to the intake manifold shorter.

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I hadn't really considered this one too much. If the restriction isn't as bad, it's possible to rig on something like dieseleux's setup, though right now, this is a bit much. I don't quite have 14" of space between the compressor outlet and the rest of the equipment in the engine to place a AWIC and loop into the intake manifold. However, it is feasible to use the space occupied by the overlaping stock IC pipes to place the AIWC... This would cut down piping length by ~4 ft too...

john.jackson9213 said:

DC

You want to cool the peak temperatures, right. You are not worried about air or EGT temps in normal operations. The best way to reduce peak operating temperatures is with water injection. Water can soak up a vast amount of heat when you really need it at high boost pressures. Since you are running 25+ psi at peak boost with no bottom end upgrades and want to put off a full engine rebuild as long as possible. My suggestion - start with EGT temp monitoring so you know the baseline, then add H20 injection. Up grade the intercooler later if you need it.

Click to expand...

You're correct, John. I'm only looking for reducing peak temps. I'm did some more drive testing in warmer weather, ~16˚C ambient temps. Looks like the SMIC was still having a min temp of 19-20˚C. After a warmed up IC was achieved, I was able to peak it at 44˚C. This is 3˚C warmer than when the ambient temps were ~7˚C. However, any heavy driving, which I foresee as I'd like to go to a few track days once I do pistons & rods, will require better cooling.

Small fmic is most reliable and most cost effective option. Something like this http://www.ebay.com/sch/i.html?_odk...313&_nkw=godspeed+type+m+intercooler&_sacat=0

The additional plumbing and mounting are not something I was looking forward to with a FMIC, frankly, but I haven't ruled anything out yet.

In other news, the logs from the 2.5" DP show ~15.8 psi @ 2000 RPM, ~26.1 psi @ 2375 RPM, 29 psi @ 3200 on flat ground in 3rd gear. This is a bit laggy actually. I've narrowed it down to a heat related problem with my N75. Looks like I get to bump over to the new plug and the cheaper variant of the solenoid sooner than expected.

Okay, so the bad N75 is in the trash! and the new one is in.

It's odd. The old one had 2 modes if you will. A good one when it was cold, and a bad one when it was warmed to the touch. During the good one, I'd peak at 15 psi under normal acceleration and the requested boost would always hover above requested by 1-2 psi under normal driving. Under the bad mode, it would cause really late spooling of the turbo and never go beyond about 7-8 psi under the same acceleration. I'll have to go thorugh my logs. I think I was able to capture both methods of operature in a drive home from work log. If anyone wants more details, hit me up here or PM me.

With the new one, I'll get 9-11 psi during acceleration and fast spool up. Took a friend for a ride, he did the logging for me, and he even commented that the B4 is almost as quiet as his MKVI. He then said that it's a diesel, it should be loud.

Now I have to work on actuator tuning. Right now I have it set to open at 4.5 inHG and stop at ~17 inHG. The boost valve is set to limit me at abou 29 psi, which I'll adjust to 32 psi. I'm still smokey, I have fuel to burn. Dyno was at 25 psi so I'd like to see what this will do. I'm told that 80% duty cycle @ 4000 RPM in 4th is what I'm aiming for. If you guys can advise for 3rd gear, I'll be more happy to check with that without having to worry about living close to 5-0.

i've changes a few N75's for the same reason, mainly sticking open when cold so overboost for the first few WOT's.

Its alot smoother now. It climbs into it instead of jumping to the top now. Its nice. But still. To dang quiet with that full exhaust on it. Lol

I don't have old logs with me, but here are some graphs of the new logs. First up, 3rd and 4th gear pulls on flat ground:

3rd:


1st 4th Gear Pull:


2nd 4th Gear Pull:


Now, I shortened the actuator rod to get better duty cycle as suggested. Based on how new this actuator is, it looks like there spring is pretty strong and cannot get it to start moving before 3 inHg. I was aiming to have it stop at 12 inHg, but got 11.5 instead.

Also note, I closed up the boost valve about a turn and a quarter from 29 psi in the logs above. It seems that it's clipping the initial 32 psi spike, but only by a little.

1st 3rd Gear:


2nd 3rd Gear:


1st 4th Gear:


2nd 4th Gear:


To me, it looks a little short, but I don't have much experience with this yet. What are your guys' thoughts?