CovertRussian's 05 LGT Build Thread

[covertrussian]

I've been really lazy to post these, mainly due to issues I ran into with spark plugs. What happened was, I did my last round of fine tuning on Tomei's Equal length header, then I swapped in the stock unequal length header, noticed that headers had significant powerloss compared to before. Turns out my spark plugs over-gapped again and it was loosing the 20whp. Since this is not a good power test to be used for comparing header vs header this is gonna be more of an AVCS angle comparison.

 

First graph has ELH vs UELH with AVCS starting at 10* and tapering to 0* by 4k rpm.

http://legacygt.com/forums/attachment.php?attachmentid=261253&stc=1&d=1516855944

 

Next I set the AVCS to be at 16* to redline. Why you might ask? Well I calculated EJ205's running a static AVCS of 16*. Thus I was really curious to see if AVCS-less EJ205's would benefit from an equal length header more then the stock unequal length.

http://legacygt.com/forums/attachment.php?attachmentid=261252&stc=1&d=1516855944

 

 

Take aways:

- AVCS 16 wanted 4* less timing by redline vs AVCS 0 to avoid knock

- UELH Runs .6psi more then ELH for the most part.

- Even with my Big16G and free flowing exhaust, overalap eats a lot of power and engine likes to be at 0* overlap by redline

- Our motors don't care about headers/turbos nearly as much, due to variable overlap (AVCS)

- Running 0 or 16* of overlap doesn't seem to make that big of a difference between the two headers. This one really surprised me, I expected the ELH to do MUCH better on higher AVCS angles.

- Spark Plug blowout might be hindering the power potential of the ELH.

- Tomei's AVCS 10-0 spike up after 6k can be regarded as virtual dyno graphing issue and thus should be ignored.

- I should have thrown these onto one graph, but I'm too lazy to redo all that work now

 

EDIT: Feeling a little more motivated this morning, so here are all of the runs on one graph.

http://legacygt.com/forums/attachment.php?attachmentid=261260&stc=1&d=1516887517

Edited January 25, 2018 by covertrussian

[covertrussian]

GrimmSpeed Port and Polished Header & Crosspipe

 

I bought this combo from utc_pyro a few months ago, simply out of curiosity on how it would compare to equal length and stock headers. This post will contain the technical sizes and my technical opinions on the designs.

http://legacygt.com/forums/attachment.php?attachmentid=261308&stc=1&d=1516944093

 

 

Port Sizes

Obviously the main reason for buying this header is for larger then stock port sizes. Detailed post about stock port sizes can be found here.

 

Left Head to Header: I measured the GS header runners at 41.9-43.6mm and they are flared out to 45.0mm at the head (which is good, since it promotes anti-reversion, more on this later). The ports are a little oval like, this is simply because it's really hard to get a perfect circle port, plus stock ports are oval too, this is where non cast headers will always be more round.

http://legacygt.com/forums/attachment.php?attachmentid=261316&stc=1&d=1516944195

 

For comparison, stock ports vary from 36.4-38.8mm. Which doesn't seem like a big difference until you hold the two headers side by side.

http://legacygt.com/forums/attachment.php?attachmentid=261314&stc=1&d=1516944195

 

Left head to Crosspipe: This is ported out to 43.1mm, but then it flares out to 47.9mm at the gasket, stock is 38.9mm at this location. The 4mm bigger port makes a big difference and that's good part of this header, but it also had a bad part, the flare out. I think this flare out is unnecessary and would go as far as saying it's detrimental at this location, since it removes the anti-reversion wall.

http://legacygt.com/forums/attachment.php?attachmentid=261317&stc=1&d=1516944195

 

Once again, 4mm doesn't seem like much until you hold them side by side.

http://legacygt.com/forums/attachment.php?attachmentid=261315&stc=1&d=1516944195

 

CrossPipe (X-Pipe): This is a very nice piece and is a fairly consistent in size. GS CrossPipe's inlet is 46.6mm consistently, stock inlet starts at 44.7mm and walls to 40.7mm, GS outlet is 46.5mm consistently while stock is 39.4mm that flares out to 41.7mm. GS X-Pipe is a much bigger throughout, and has a much better flowing flex section.

http://legacygt.com/forums/attachment.php?attachmentid=261319&stc=1&d=1516944195

 

Back to why the header flare out is detrimental: Since GS Xpipe is 46.6mm and last part of the header was 47.9mm, this creates a 1.3mm wall that gasses will now hit. You always want the flow to go from smaller diameter pipe into a bigger pipe, otherwise around creates restrictions. If the header wasn't flared out, this wouldn't be an issue. Another benefit of smaller into bigger pipe design is anti-reversion effects that it has.

 

http://legacygt.com/forums/attachment.php?attachmentid=261324&stc=1&d=1516949999

 

 

CrossPipe to Right Head: This starts at 47.3mm and tapers down to 41.9mm, this flare out is actually really good since it removes that flow wall that the bigger GS x-pipe would otherwise experience. Stock xpipe to header inlet size is 39.7mm.

http://legacygt.com/forums/attachment.php?attachmentid=261320&stc=1&d=1516944195

 

Right Head to Header: I did measure the ports being 1mm smaller then left head's here, measuring at 40.9mm at smallest diameter. This is not a big deal, and might be done on purpose since this head is closer to the exit.

http://legacygt.com/forums/attachment.php?attachmentid=261321&stc=1&d=1516944195

 

Header to UpPipe: This part is ported out to 45.2mm, which is great since stock is only 41.7mm. But it also has the flare out, this time to 50.6mm! This flare out is once again unnecessary and is detrimental, since it's so big it forced me to port out my GrimmSpeed Up Pipe too (will be posted in next post).

http://legacygt.com/forums/attachment.php?attachmentid=261322&stc=1&d=1516944195

 

Installation

This header is drilled/tapped for EGT gauge, even though utc_pyro was kind enough to give me one, I didn't want to bother with installing it just yet. Instead I used a spare 1/8NPT SS bung from my TGV deletes.

http://legacygt.com/forums/attachment.php?attachmentid=261318&stc=1&d=1516944195

 

Bolted up just fine:

http://legacygt.com/forums/attachment.php?attachmentid=261309&stc=1&d=1516944195

 

The X-Pipe is placed properly for easy viewing pleasure from above

http://legacygt.com/forums/attachment.php?attachmentid=261310&stc=1&d=1516944195

 

I started the car, but it had a ton of exhaust leaks with stock sized gaskets. This is because I unbolted everything to take measurements. Luckily utc_pyro threw in a bunch of gaskes, thank you kind sir! I unbolted the X-Pipe in plate, look at the gap that is has, it needs the extra thick GS gasket to reduce stretching.

http://legacygt.com/forums/attachment.php?attachmentid=261311&stc=1&d=1516944195

 

On other side I was able to use a thinner gasket (I didn't have any more extra thick ones anyway!)

http://legacygt.com/forums/attachment.php?attachmentid=261312&stc=1&d=1516944195

 

Now all done and without exhaust leaks, notice the right header turned very white after running for a day, not sure why.

http://legacygt.com/forums/attachment.php?attachmentid=261313&stc=1&d=1516944195

 

Results

After fine tuning, I saw a pretty decent midrange bump (~10whp/15wtq), but overall power stayed the same. The header did want 2* less timing, which is usually a sign of engine efficiency going up.

http://legacygt.com/forums/attachment.php?attachmentid=261323&stc=1&d=1516947734

Edited January 26, 2018 by covertrussian

[covertrussian]

Since the header came with a GrimmSpeed UpPipe, figured I would use it over my old Invidia one.

 

http://legacygt.com/forums/attachment.php?attachmentid=261325&stc=1&d=1516950101

 

This uppipe's inlet measures in at 46.8mm and turbo outlet is also 46.8mm

http://legacygt.com/forums/attachment.php?attachmentid=261326&stc=1&d=1516950101

 

Since my header has a massive 50mm outlet, which matches the gasket, I used my compressor to remove that flow restriction "wall", from the Up Pipe. By removing the sharp corner, it made the transition to a smaller diameter be more gradual and shouldn't impede flow.

http://legacygt.com/forums/attachment.php?attachmentid=261327&stc=1&d=1516950101

[Wasted Potential]

I would've figured that increasing the size even marginally would shift the curve to the right and atleast effect low RPM power. Seems from the factory a lot of things (and aftermarket performance) could use simple revisions?

 

Theoretically, if you were to double (or just increase marginally) the volume of the header/x-pipe before the turbo; would this effect total boost or induce overboost somehow?

[utc_pyro]

On your ELH-vs-stock comparison, it looks like you have the car weight set higher on the tomei headers. Correcting that back to equal, wouldn't that mean the ELH LOST power? Also did they end up requiring less timing like the Grimmspeed ported ones did?

 

Interestingly the Grimmspeed data seems to match the old PnP set marketing material. Mostly getting a midrange bump.

Edited January 26, 2018 by utc_pyro
clarity

[covertrussian]

I would've figured that increasing the size even marginally would shift the curve to the right and atleast effect low RPM power. Seems from the factory a lot of things (and aftermarket performance) could use simple revisions?

 

Theoretically, if you were to double (or just increase marginally) the volume of the header/x-pipe before the turbo; would this effect total boost or induce overboost somehow?

 

Right that's what you would expect and is actually what I saw with equal length header (mainly due to slower spool). But I guess stock vs ported is not that big of a difference to really worry about it.

 

In theory it shouldn't effect total boost or overboost since your doing things before the wastegate. Doing mods after the wastegate will indeed cause boost issues (hence stage 2 downpipe needs to be retuned for)

 

On your ELH-vs-stock comparison, it looks like you have the car weight set higher on the tomei headers. Correcting that back to equal, wouldn't that mean the ELH LOST power? Also did they end up requiring less timing like the Grimmspeed ported ones did?

 

Actually that's because I wasted 25lbs of gas retuning the UEL header (and driving around town). I do simple math to figure this out (odometer / gauge mpg *6.25lbs), thus I feel weight is actually accurate enough. One thing to notice is EL is running less boost, so at same boost it should be slightly ahead of UEL ($700 worth of ahead though? Not to me )

 

Also, this is where I say, take the EL vs UEL comparison with a big grain of salt, since they were done on overgapped spark plugs. This is why it took me so long to post that one up, I spent weeks scratching my head and just didn't want to think about it anymore. But as I started writing the post, I actually understood the issue, and how bad of a comparison it is thus I made it be geared towards showing AVCS difference instead.

 

Why the overgapped plugs would be unfair to Tomei EL Headers? Since the header flows better, it will be more prone to spark blow out, which would cause a bigger power loss. For this reason I cannot, in good faith say that it's an accurate enough comparison. I still think that a more proper comparison is this post.

 

Timing: If you look at the the two graphs, on bottom there will be IAT and Total IGN, which is pretty much the same between ELH and UELH. I found that the stock UEL made the most power with the same WOT timing as the ELH at the time of testing (I know that before I said Tomei wanted +2* of timing, but that was with warmer temps).

 

What I did find out this time around is the UEL would knock a lot leading up to WOT columns and in columns with AVCS greater then 5*, thus needed much less timing in those areas. EL Header had better reversion suppression thus it allowed me to tune past MBT in those areas, and still wouldn't be knock prone.

 

Finally, the real reason I decided to sell the EL header is, it didn't gain me any MPG at all. If it gained me at least 1mpg I would still think of it as a worthwhile investment, but in the end marginal power gains (at my boost levels) and no mpg gain made it be not worth the cost.

 

Interestingly the Grimmspeed data seems to match the old PnP set marketing material. Mostly getting a midrange bump.

 

I thought the crosspipe alone was supposed to increase power by that much. I expected a little bit better to be honest

Edited January 26, 2018 by covertrussian

[d22597]

What kind of g/s MAF numbers are you running? I was under the impression headers are marginally beneficial until you’re in the 300+ g/s range. Curious if the GS / ELH / stock comparison would yield different results at higher air flows.

[covertrussian]

What kind of g/s MAF numbers are you running? I was under the impression headers are marginally beneficial until you’re in the 300+ g/s range. Curious if the GS / ELH / stock comparison would yield different results at higher air flows.

 

I'm running about 250 g/s with GS UEL and 25-35F weather. But our measurement of gram/sec is not accurate enough to be treated as truth. I would go by inlet boost instead. I believe that running only 13psi is not enough to make a difference, running more boost might possibly make a bigger difference.

 

But to counter that, more boost means more backpressure build up in manifold, which means manifold design matters even less

[covertrussian]

Has anyone swapped in a 07+ LGT, 08+ WRX or 2006-2007 WRX transmission into the 05/06's? While doing some research and math on gear ratios between cars, I noticed that 07+ LGT's and 08+ WRX's have a 3.900 final gear and that 06-07 WRX's have 3.700 final gear, while having the same 5th gear as our cars (0.738). Our final gears are 4.111.

 

Why? Because it would greatly reduce the highway RPM. Here is an example with 225/45/17 (24.97") tires.

2005 LGT (4.111): 2,859rpm @ 70mph

2007 LGT (3.900): 2,712rpm @ 70mph

2006 WRX (3.700): 2,573rpm @ 70mph

2005 OBX (4.444): 3,090rpm @ 70mph

 

For comparison sake, here is the 6 speed's with same tire:

2007 LGT: 2,598rpm @ 70mph

2007 STI: 2,778rpm @ 70mph

 

And just for Flinkly OBX on stock 225/55/17 (26.7") tires:

2005 OBX (4.444): 2,890rpm @ 70mph

 

This means that the 2006-2007 WRX rev's lower at 70mph then even the 6 speed Spec B's.

 

Anyone looking to sell their WRX trans?

Edited January 30, 2018 by covertrussian

[Flinkly]

you should add the OBXT into your rev list. ya know, cause i drive one and am too busy to do the numbers.

 

and where's the paypal donation link?

[covertrussian]

you should add the OBXT into your rev list. ya know, cause i drive one and am too busy to do the numbers.

 

and where's the paypal donation link?

 

On 225/45/17:

2005 OBX (4.444): 3,090rpm @ 70mph

 

On stock 225/55/17:

2005 OBX (4.444): 2,890rpm @ 70mph

[covertrussian]

Question for you guys, What are the limits of the stock intercooler? I thought some folks were pushing close to 300whp corrected on them? The car is making ~298whp uncorrected at 25F, and ~265whp SAI corrected for temp and barometric pressure. I verified that the car is indeed making about 260whp at 60F.

 

Background on why I'm asking:

I've spent about 3 nights in past week testing my stock intake and my custom intake (which has 1/2 less intake vacuum!), and the power differences where just non-existing, nothing conclusive at all. The custom intake also is boosting .5psi more, so I expected power gains from that alone. Highway gas mileage does improve, which tells me that overall engine efficiency did go up.

 

The following mods made no measurable differences for me, even after fine tuning:

Downpipe: Going from 2.5" downpipe to 3" downpipe (same amount of backpressure)

Exhaust: Stock to 3" catback (-3psi back pressure)

Header: EL to UEL (no real difference)

Intake: Stock to 3" Custom (1/2 less intake pressure)

 

TGV's are on the to do table, but I'm not sure they will make any impact either (since people are pushing over 300whp on stock TGV's still). Which gets me to the point of Intercooler. Maybe I'm just maxing out the ability of the stock intercooler? If the intake with .5psi more doesn't gain any power, perhaps the intercooler is just too inefficient at removing heat (being a tube & fin design and all). This is why I did the intake testing at 25F, this reduced the possibility of heat soaking.

Edited February 1, 2018 by covertrussian

[utc_pyro]

There is an easy way to test that! Get a GM IAT sensor, install it in the intercooler end tank, and wire it to the EGT input. The pull up resistor inside the ECU is the same as the one on the stock IAT sensor, so you can use the same scaling people use for SD builds.

 

The intake should have lowered your PR making the turbo slightly more efficient and put less heat load on the intercooler. So that should have made things better if the IC was your limitation.

[covertrussian]

Man your a genius! I've had this spare IAT sensor chilling in my room for 5 years .

 

http://legacygt.com/forums/attachment.php?attachmentid=261797&stc=1&d=1518325482

 

Now the hard part is finding where I can put it. I wonder if I could just tap it straight into the intercooler.

Edited February 11, 2018 by covertrussian

[utc_pyro]

I just drilled and tapped mine directly, but it’s also aluminum. On the plastic one I see no reason not to do the same, but use some plastic epoxi in the threads and around the outside for additional support.

[covertrussian]

Do you remember the threads and pitch? It's been so long since I bought that bung I don't remember anymore.

[utc_pyro]

Yours is 3/8” NPt

[Sgt.Gator]

Your answer is in this tech article. Scroll down to #7 to see HP limits.

https://www.mishimoto.com/engineering/2015/04/drop-intake-temperatures-drop-track-times-drop-mouths-the-ultimate-guide-for-intercooler-selection/

[covertrussian]

Thanks! Will try to calculate it out tonight. Meanwhile, I'm also trying to find the best spot to put the IAT bung into, half tempted to just throw it in the intake manifold...

 

As for post intercooler temps, what's the typically "good" numbers? I was looking at my logs yesterday from my G20 (which has a small FMIC: Precission 350hp core), at 74F Ambient, IAT's started at 100F and ended at 108F by end of the pull for the virtual (live road) dynos posted in this post, during 80F autocross days, I would see my IAT's jump to around 135F tops though, but they wouldn't drop even with 60 seconds of hard racing .

 

Now looking up the specs for that core, I came across this site:

 

They are typicall rated to 350 hp. From our data we believe this core to be able to support 350whp.

 

Intercooler Dimensions:

 

26 3/4" L

6 3/8" H

3.5" D

 

2.5" inlet/outlet

 

So if that FMIC, which is MUCH better then any of our TMIC's honestly, is only rated for 350bhp being outside of the engine bay, there is a good chance that I'm just maxing out the stock TMIC.

 

300whp uncorrected with 25% drivetrain loss = 400BHP. And even 260whp corrected = 347bhp.

[Sgt.Gator]

Don't put the IAT bung in an aluminum intake manifold, it will read too hot from the mani getting heat soaked. Not critical here but it is for SD tuning.... it will read hot, the tune will go too lean to compensate for thinner air when in reality the air is cooler and denser; bang.

 

IMHO any turbo bigger than stock should have an aftermarket TMIC or FMIC.

Edited February 2, 2018 by Sgt.Gator

[covertrussian]

Don't put the IAT bung in an aluminum intake manifold, it will read too hot from the mani getting heat soaked. Not critical here but it is for SD tuning.... it will read hot, the tune will go too lean to compensate for thinner air when in reality the air is cooler and denser; bang.

 

Would you say the same applies to even stock plastic manifold?

 

IMHO any turbo bigger than stock should have an aftermarket TMIC or FMIC.

 

Agree with this completely and normally would run a better intercooler, but shelling out even $500 for a Top mount always seemed like a waste of money (since it still will heat soak).

 

This actually brings an interesting question, which turbo would benfit more from a better intercooler, stock small turbo or bigger turbo? Small turbos will produce more heat due to their restrictive nature, while bigger turbos will produce cooler charge. This is why you can make more power at less boost on a bigger turbo.

 

If you need to run 18psi to make 300whp on a stock turbo, you should be able to make that same power at 14psi on a bigger turbo. In theory the charge should be cooler too, requiring less cooling, thus being more forgiving to less efficient intercoolers.

[covertrussian]

Measured the stock intercooler tonight:

 

Length: 10.25"

Height: 9.31"

Thickness: 2.5"

Bar Height: 0.22"

Bar QTY: 16

 

Following Mishimoto's formula's:

Core Flow Area (in²) = Core Length (in) x Bar Height (in) x # of Bars
Charge-Air Surface Area (in²) = Core Flow Area (in²) ÷ 0.45
Internal Flow Area (in²) = Charge-Air Surface Area (in²) ÷ Core Thickness (in)

 

I get the following values:

Core Flow Area: 36.08 in²
Charge-Air Surface Area: 80.18 in²
Internal Flow Area: 32.07 in²

 

Which puts the intercooler right under the 325whp mark, assuming it's a high-density core, if it's not then it would be less.

 

 

Next up did the same measurements for Precision 350 hp...

 

Length: 17.5"

Height: 6.38"

Thickness: 3.5"

Bar Height: 0.44"

Bar QTY: 7

 

Core Flow Area: 53.9 in²
Charge-Air Surface Area: 119.78 in²
Internal Flow Area: 34.22 in²

 

This fits well with the advertised HP, but Mishimoto's formula is not right, if I reduce the core thickness from 3.5" to 2.5" internal flow increases to 47.91 in²

[utc_pyro]

Would you say the same applies to even stock plastic manifold?

 

It shouldn't. Go touch your plastic manifold aster driving vs an STI. Big difference.

[covertrussian]

It shouldn't. Go touch your plastic manifold aster driving vs an STI. Big difference.

 

Right, that was my thoughts too.

 

As for Aluminum manifold heat soak deal, I would run thermoblok spacers on my SR20. The kit would have a head to manifold runners spacer, then runners to plenum spacer, finally manifold to throttle body. Overkill, but works

[Sgt.Gator]

Would you say the same applies to even stock plastic manifold?

 

No. It will probably be fine for your purpose.

 

 

Agree with this completely and normally would run a better intercooler, but shelling out even $500 for a Top mount always seemed like a waste of money (since it still will heat soak).

 

This actually brings an interesting question, which turbo would benfit more from a better intercooler, stock small turbo or bigger turbo? Small turbos will produce more heat due to their restrictive nature, while bigger turbos will produce cooler charge. This is why you can make more power at less boost on a bigger turbo.

 

If you need to run 18psi to make 300whp on a stock turbo, you should be able to make that same power at 14psi on a bigger turbo. In theory the charge should be cooler too, requiring less cooling, thus being more forgiving to less efficient intercoolers.

 

You're over analyzing this. Stock turbo, keep stock intercooler as long as it works (no damage). The gain with an aftermarket intercooler on a stock turbo will not be worth the cost.

 

Aftermarket larger turbo get an aftermarket larger intercooler.