IR89 - back in action.

Post by **Piazza_man** » Sat Jan 26, 2013 8:30 am

I've gone back over BW site and I'm trying to understand why you opted for twin scroll. Do you see a performance value in this. I understand why you need 2 BOVs but I didn't think these engines were known for boost creep, unless your mega squirt doesn't electronically control boost levels. Please forgive my ignorance and short comings on mega squirt tech. You may have already covered this elsewhere.

IZU069 · Post by **IZU069** » Sat Jan 26, 2013 9:43 am

ImpulseRocket89 wrote:It allows full sequential. That symmetry acts as a 12-1 crank signal and a 1 tooth cam signal, and thats all it needs for everything....

D'oh! I don't know why I didn't "see" that outer slot! Obviously therefore it does sequential (as a cam disc).

And rough slot side "ends" are irrelevant, it's only the leading &/or lagging that matter. (But compare the "perfect" slots even on the 360 slots of the OEM rotors, and they are 30 years old!)

ImpulseRocket89 · Post by **ImpulseRocket89** » Sat Jan 26, 2013 11:06 am

eyecon wrote:I've gone back over BW site and I'm trying to understand why you opted for twin scroll. Do you see a performance value in this. I understand why you need 2 BOVs but I didn't think these engines were known for boost creep, unless your mega squirt doesn't electronically control boost levels. Please forgive my ignorance and short comings on mega squirt tech. You may have already covered this elsewhere.

Twin scroll has advantages over single when you pair the cylinders properly. On our engine with a 1-3-4-2, you would pair cylinders 1 and 4 on one side, and 2 and 3 on the other. This pairing prevents exhaust pulses from fighting each other.

Without going into a huge book worth of text, by separating the opposing exhaust gasses until they reach the turbine wheel it reduces manifold pressure, and increases efficiency by causing something similar to a scavenging effect at the turbine wheel. It is just overall more efficient, but where it shines is something you will never see on a dyno graph. Transient boost response and part throttle response is much faster. Overall a twin scroll will have better spool up while being able to flow more efficiently.

BTW, those are two wastegates, not BOV's.

My megasquirt does control boost as well, the solenoid is actually in the picture with all the other goodies (far right and hard to see lol).

IZU069 wrote:
ImpulseRocket89 wrote:It allows full sequential. That symmetry acts as a 12-1 crank signal and a 1 tooth cam signal, and thats all it needs for everything....
D'oh! I don't know why I didn't "see" that outer slot! Obviously therefore it does sequential (as a cam disc).

And rough slot side "ends" are irrelevant, it's only the leading &/or lagging that matter. (But compare the "perfect" slots even on the 360 slots of the OEM rotors, and they are 30 years old!)

The leading and trailing edges are actually smooth. It is only the ends that are a bit rough. It still could use a little smoothing with a fine file.

Post by **Piazza_man** » Sat Jan 26, 2013 11:53 am

Good stuff. Thanks for clarifying things for me. You've certainly put a lot of thought into all aspects if the build. My bad about the wastgate/BOV mixup. I had wondered why you didn't go for the internal wastgate option, particularly as the EFR technology offers the same performance as the external version, and most probably would have been simpler and easier to install (it's probably another stupid question lol) :/

ImpulseRocket89 · Post by **ImpulseRocket89** » Sat Jan 26, 2013 12:37 pm

I went with the twin external for 2 reasons. First, the 40mm internal gate, by my math, would choke flow past about 30% wastegating on a 2.6 under specific scenarios, potentially causing boost creep (my math could be wrong, but under many VE tables they call ended up that way). Secondly, To run the 1.05 turbine, which is what I wanted, I had no choice but to run externals, and being twin scroll, it is best to keep both sides separated until after they are dumped. You could run a bigger single external if you kept both sides divided until the valve face.

I got over to my new place and... MORE shiny stuff!

My fuel pump, TB, and Shifter (going to be modified for my setup) arrived, along with most of the stuff I need to build my intake manifold. If it looks like I have an awful lot of Fuel rail stock and Flange plate it's because they only sell it by the foot. I also ordered a lot more intake runner pipe than I would ever need, but better too much than not enough. Those velocity stacks are even better looking in person. I need to buy some 11ga bends and sheet stock, but otherwise, that is everything.

Post by **Piazza_man** » Sat Jan 26, 2013 12:47 pm

That makes sense. Thanks. At the risk of annoying you again what size TB is that?

ImpulseRocket89 · Post by **ImpulseRocket89** » Sat Jan 26, 2013 5:15 pm

Not annoying me at all. It's a 75mm TB for a 94-98 Mustang GT. I could have also gotten the 70, but for airflow needs at higher boost the 75 works better. Considering I am going with a 3" (76.2mm) charge pipe from the intercooler it just kinda works well that way.

I am wondering how my throttle response will be, but I don't imagine it will be too bad. The plenum volume will really determine that paired with the size of the TB too. If I remember right the stock single blade TB on the factory plenum I have now is about 60mm (not sure on that, but its close).

It's well thought out because I have been scheming and planning this build for years and years. Now I have the chance to make it happen.

Post by **Piazza_man** » Sat Jan 26, 2013 10:52 pm

Looks like I'll have to get another TB as mine is 65mm I think. I might see if I can find a Nissan Infinity Q45 v8 TB from an inport wrecker. These engines have 75mm bore size too with a 44.2cm2 cross sectional area. What volume of plenum chamber would you recommend to achieve neutral pressure balances at top end?

ImpulseRocket89 · Post by **ImpulseRocket89** » Sun Jan 27, 2013 5:23 am

From everything I have learned, 1.5X engine displacement is generally the balance point between peak power and throttle response, so I am going to try to stick to around that volume - which is 3.9L. For all out power around 2x supposedly works best, but I dunno.

I will say this, I have been toying with the idea of trying to build a dual chamber plenum for better air distribution.

It may not be the sexiest looking thing out there, but for pure function it's awesome. Audi uses similar designs in their race cars. Not to mention, that above design would be relatively easy to replicate.

Thread those are from with other pictures. It also has a link to hybridz forum on same subject.
http://honda-tech.com/showthread.php?t=3016531a

Post by **Piazza_man** » Sun Jan 27, 2013 11:10 am

That makes terrific sence and the issue injector starvation at the first and 2nd cylinders would become a bigger issue at full boost and tilt. I also read it has a vastly improved mid range response too.
The link below is the place I was going to use for my plenum setup.
http://www.ozgemini.com/forums/non-tech ... hp?t=29271

Very nice presentation but the good thing is that they can do specific custom plenums on request. It wouldn't be hard to incorporate the sub-chamber on the existing chamber shown in the link above. But the issue will then come down to the R&D to get the right turbulence and slot size between the two chambers just right. Hmmm maybe just angle the TB a bit towards runners 1&2. Maybe a good compromise. That link you put up to hybrids.org really highlighted the use of CAD drawing and computer flow and turbulance modelling/testing. Some really involved stuff there.

ImpulseRocket89 · Post by **ImpulseRocket89** » Sun Jan 27, 2013 7:26 pm

That does look pretty nice. I am not using the factory lower manifold either though. In fact, I plan on keeping the runner lengths fairly short, straight, and all the same length.

If I do a double plenum I will probably shape it similar to the picture I posted above. My only real issue would be making that tapered section. The easiest way would be to cut it from flat sheet and slip roll it, but I don't have a slip roller. Option B would be to buy a section of tubing of the proper diameter for the TB side, and V cut the length down to the small by measuring out the small end diameter. The issue with that is, trying to hand form .125" thick 6061-T6 aluminum into a conical shape. Not saying it is impossible, but it sure as heck wouldn't be very easy either.

All of the above is why I am probably going to stick with a more traditional manifold design. I would love to try it though.

Post by **Piazza_man** » Sun Jan 27, 2013 10:50 pm

Maybe this would be a good compromise:

Images courtesy of Metalcraft Marine. Disregard the TB facing the opposite way. It's the wedge shape tapered design that is what I'm getting at here.

ImpulseRocket89 · Post by **ImpulseRocket89** » Mon Jan 28, 2013 2:38 am

That was more the plan, anyway. Similar to that one, or the manifold on this red Gem with a silly twin turbo system lol.
http://www.starlyon.com/bugle/gemini/4z ... em25ag.jpg

ImpulseRocket89 · Post by **ImpulseRocket89** » Mon Jan 28, 2013 6:24 pm

Getting her ready for the move to the new place. Hood back on, and for the first time of me owning it, the hood is on with an engine actually under it. Garage is kinda messy because I like to organize by first destroying.

She looks in a sorry state, but I have a new grille for the front and the missing headlight is in a box elsewhere for whatever reason I removed it for. I have to get my hands on a couple of little trim pieces and a drivers side window, but otherwise she is complete....just needs a bath.

Sorry for the quality. This was taken by my friend with his phone camera.

Post by **Piazza_man** » Mon Jan 28, 2013 6:50 pm

Hope all goes well in the move. How far are you moving?