Subaru Impreza build thread...

JapCarForum Cars, Cars, Cars! Project Cars Subaru Impreza build thread...

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Shaun TDI
Junior Member

07-09-2018, 06:11 AM

#11

With the power steering pump and the alternator added, it's now pretty much ready to go into the car!

[Image: file-41.jpg]

The belt that you see hanging off is infact the belt for the AC - this has to go on behind the alternator belt. The AC unit is still attached to the car...

I decided the other night that i wasnt happy with the condition of the power steering pump.

Before....
[Image: file-43.jpg]

After....

I also found the gaurds for the belts and gave them a clean up too....
[Image: file-45.jpg]

You can also see from this picture that the alternator has been cleaned too. This really was an eye-sore before and stood out like a sore thumb. It's amazing what you can do with a wire wheel and a few spare hours.
If the truth be known, i've actually surprised myself with this project. The original intention was never to produce something that looked like a show car, but just to have something that looked like it had time and effort spent on it.
Tonight I shall be fitting the HKS GD Max clutch and flywheel assembly, then tomorrow, if all goes according to plan I shall be attaching the gearbox to the engine and installing the whole thing.

First job - get the engine off the engine stand. Strangely enough, this isn't as easy as it sounds. When the whole thing has been built up, you dont really appreciate exactly how much the whole thing weighs.

[Image: file-46.jpg]

The clutch - The HKS GD Max.
One of the nicest twin plate clutches i think i've ever driven. No heavier than a standard clutch and many times more reliable and in this case, pretty much future proof. It would have been completely pointless to put a lesser spec clutch in, only to have to change it later on. I was extremely cautious about spending almost £1,300 on a clutch and flywheel set-up but overall, I'm glad i did.

[Image: file-47.jpg]

A few hours, some cuts and bruises later....

[Image: file-51.jpg]

OK - So I started to run the car in at the weekend. I've now done just over 720 miles since Sunday morning and so far so good.
She doesn't appear to have used any oil and there are no leaks, bangs or knocks. The longer she runs and the more mileage she does, the stronger she feels.
When i had hit the 500 mile mark, i started to introduce some boost and my god, it feels so much better than before. It's much more urgent than before and feels stronger right from the word go.
For the last 100 miles, i've taken the boost up to 0.5bar which feels even better. Unfortunately i'm still working with a 4,000rpm rev limiter but she still does well, even with one hand behind her back!

When its finished, she'll rev to 8,500rpm and hopefully be good for 1.6bar.
The engine bay pics are going to have to wait. There are a few bits of pipework that don't look very nice so once these have been tidied up, I'll get the camera out.
She's all run and mapped but it didn't make the power I was after. Testing has revealed that there are currently 2 restrictions.
1. The standard intake pipe that comes directly off the turbo seems to be causing issues
2. The exhaust system isn't good enough. At high rpm (anything over 5000rpm) the exhaust after the turbo is managing to gain 0.35bar of back pressure. Closer examination reveals that the diameter shrinks by 3/4 of an inch about half way down the car and also the back box seems to be slowly destroying itself too.
The next step will be a custom made 'turbo back' system. For now, it'll have to do. I've run out of time and the Nurburgring trip approaches...

It had before the engine rebuild:
297.2bhp & 235.0 lb/ft before the rebuild, running 1.2bar of boost.
Now has:
306.5bhp & 285.3 lb/ft after the rebuild but still running the same boost.

Because of the restrictions, the torque drops off like a stone past 5,000rpm. I was aiming to have at least 330bhp at the wheels and then draw the line there. Any more than that and I'd be looking at a new turbo and possible compromising the gearbox.

It still goes like stink though......

Shaun TDI

07-09-2018, 06:11 AM #11

With the power steering pump and the alternator added, it's now pretty much ready to go into the car!

[Image: file-41.jpg]

[Image: file-42.jpg]

The belt that you see hanging off is infact the belt for the AC - this has to go on behind the alternator belt. The AC unit is still attached to the car...

I decided the other night that i wasnt happy with the condition of the power steering pump.

Before....
[Image: file-43.jpg]

After....
[Image: file-44.jpg]

I also found the gaurds for the belts and gave them a clean up too....
[Image: file-45.jpg]

You can also see from this picture that the alternator has been cleaned too. This really was an eye-sore before and stood out like a sore thumb. It's amazing what you can do with a wire wheel and a few spare hours.
If the truth be known, i've actually surprised myself with this project. The original intention was never to produce something that looked like a show car, but just to have something that looked like it had time and effort spent on it.
Tonight I shall be fitting the HKS GD Max clutch and flywheel assembly, then tomorrow, if all goes according to plan I shall be attaching the gearbox to the engine and installing the whole thing.

First job - get the engine off the engine stand. Strangely enough, this isn't as easy as it sounds. When the whole thing has been built up, you dont really appreciate exactly how much the whole thing weighs.

[Image: file-46.jpg]

The clutch - The HKS GD Max.
One of the nicest twin plate clutches i think i've ever driven. No heavier than a standard clutch and many times more reliable and in this case, pretty much future proof. It would have been completely pointless to put a lesser spec clutch in, only to have to change it later on. I was extremely cautious about spending almost £1,300 on a clutch and flywheel set-up but overall, I'm glad i did.

[Image: file-47.jpg]

[Image: file-48.jpg]

[Image: file-49.jpg]

[Image: file-50.jpg]

A few hours, some cuts and bruises later....

[Image: file-51.jpg]

OK - So I started to run the car in at the weekend. I've now done just over 720 miles since Sunday morning and so far so good.
She doesn't appear to have used any oil and there are no leaks, bangs or knocks. The longer she runs and the more mileage she does, the stronger she feels.
When i had hit the 500 mile mark, i started to introduce some boost and my god, it feels so much better than before. It's much more urgent than before and feels stronger right from the word go.
For the last 100 miles, i've taken the boost up to 0.5bar which feels even better. Unfortunately i'm still working with a 4,000rpm rev limiter but she still does well, even with one hand behind her back!

When its finished, she'll rev to 8,500rpm and hopefully be good for 1.6bar.
The engine bay pics are going to have to wait. There are a few bits of pipework that don't look very nice so once these have been tidied up, I'll get the camera out.
She's all run and mapped but it didn't make the power I was after. Testing has revealed that there are currently 2 restrictions.
1. The standard intake pipe that comes directly off the turbo seems to be causing issues
2. The exhaust system isn't good enough. At high rpm (anything over 5000rpm) the exhaust after the turbo is managing to gain 0.35bar of back pressure. Closer examination reveals that the diameter shrinks by 3/4 of an inch about half way down the car and also the back box seems to be slowly destroying itself too.
The next step will be a custom made 'turbo back' system. For now, it'll have to do. I've run out of time and the Nurburgring trip approaches...

It had before the engine rebuild:
297.2bhp & 235.0 lb/ft before the rebuild, running 1.2bar of boost.
Now has:
306.5bhp & 285.3 lb/ft after the rebuild but still running the same boost.

Because of the restrictions, the torque drops off like a stone past 5,000rpm. I was aiming to have at least 330bhp at the wheels and then draw the line there. Any more than that and I'd be looking at a new turbo and possible compromising the gearbox.

It still goes like stink though......

Shaun TDI
Junior Member

07-09-2018, 06:12 AM

#12

The exhaust restriction has now been removed! Hoorah!!
The Hayward & Scott system has now been replaced with an unknown make taken from one of our drag racing clients. He's now chasing 900bhp so we've had to custom fabricate a system for him with much larger proportions. As a result, his old system is redundant so we made a deal and now its on my car. With some mild fabrication work to make it fit, it certainly looks more 'Japanese' and is considerably louder too - something I'm not particularly happy about as it retracts from the whole 'stealth' look that i originally set out to achieve but never mind...
I can tell immediately that the exhaust restriction has disappeared as actuator boost has increased from 0.80bar to 0.95bar. Low boost was previously set to 1.00bar and is now peaking at 1.18bar
I haven't had the real opportunity to give it the beans on high boost yet, as the F-Con only has projected fuel and ignition maps past 1.35bar and i don't want to do it any harm.
Also recently, there's been a hint of miss-fire at high rpm's and i have my suspicions about the coil pack. It its the original coil pack then that means it has now contended with 112,000 miles of typical Impreza usage. I can forgive it for wanting to give up the ghost! I'll put an new one on the Christmas list...
Away from the engine side of things, just after the BHP Show @ Lynden Hill i sought out to buy a second set of wheels to fit track specific tyres to so that I'm not destroying my road tyres.
£100 bought me a set of 7.5 inch wide standard 16" Impreza wheels (identical to what i currently have) which have now been fitted with Yokohama Advan AO48's which cost me the princely sum of nothing!! Bonus.

it's now been on the dyno again and we've made some further changes to the set-up. It's now been re-mapped for the new exhaust system. We've also managed to eradicate the missfire issue too - this was simply a case of running more dwell time (charge time) for the coil pack via the HKS F-Con ECU. Whilst this has cured the problem, it may hasten the demise of the coilpack itself but i was prepared to buy another one anyway. It simply means that i wont have to do this straight away anymore.
She now has 316.5 bhp and 276.4 lb/ft of torque at the hubs. This means that losing the restriction in the exhaust has given me another 11bhp but lost me 8.9 lb/ft of torque. The reduction in torque is entirely deliberate because now the torque can be kept up for longer, resulting in the higher bhp. As for the restriction before the turbo, this will have to be solved another time.
In its current spec, i cannot raise the boost any further as we are now getting very close to maxing out the injector duty cycle. Apparently, i should have 555cc Nismo injectors although that is now looking doubtful, because if they were then i'd have more more fueling capacity than i do right now.

[Image: file-53.jpg]

Shaun TDI

07-09-2018, 06:12 AM #12

Shaun TDI
Junior Member

07-09-2018, 06:14 AM

#13

Next set of upgrades...
Found these little beauties on eBay:

[Image: file-60.jpg]

They're designed to go on the sides of the front bumper to allow air to be fed into the inner arch liners. These are ideal for the plans I have to relocate my induction kit and feed the engine cooler, denser air, thus hopefully yielding a bit more power.
It'll also provide me a solution for removing the pesky MAF sensor which is no longer used.

This what it'll look like mocked in place with a little bits double sided sticky take. It was important to get the location right - not only because I didn't want them looking out of place but also because I plan on ducting the air and want to make sure that the ducting doesn't collide with anything behind the bumper.

[Image: file-61.jpg]

It turns out that the intercooler pipework is in the way of my plans so I set about re-manufacturing it. Most people would think twice about taking a chop-saw to their HKS intercooler kit but needs must...
As you can see from the picture below, the original route for the HKS pipe work runs straight through the middle of the void where the standard air box used to be.

[Image: file-62.png]

I need to move the whole assembly towards the front of the vehicle to allow enough room for a new induction system.

Shaun TDI

07-09-2018, 06:14 AM #13

GRRRRR!!!
The coil pack has now finally given up the ghost. After prolonged periods of hard driving, i cant run any more than actuator boost pressure (0.8bar) as the coil pack suffers massively from heat soak and gives up on me.
The plan now is to look into switching the car over to either an uprated coil pack or running individual coils like the earlier Subaru's do. Ideally, i'd like to keep the single coil pack as it means less modified wiring, plus i know that i can purchase some seriously powerful coils from companies like ACCELL or alike.
The standard Subaru coil pack is £297.00+ vat and pumps out 29,000 volts
An uprated ACCELL unit costs $69.00 and pumps out 47,000 volts - almost twice as much at a fifth of the cost! The only real downside is that i'll have to have custom leads made to suit the application but I've already spoken with the guys at Magnecor and they say its all possible.
All i know id that driving it around at 0.8bar is fun but its not a patch on 1.4bar....

Further diagnosis revealed that the coilpack wasn't the only issue.
Combine a new coilpack with 4 new plugs and a smattering of di-electric grease and bingo.

So.....
Spent a bit more time making the car a little more track specific. a month or so ago i managed to buy a pair of Cobra Imola II bucket seats in the same colour scheme as the original interior.
This week i spent a little time fitting them with some bespoke OMP seat sub frames.

[Image: file-55.jpg]

[Image: file-56.jpg]

[Image: file-57.jpg]

[Image: file-58.jpg]

[Image: file-59.jpg]

Next set of upgrades...
Found these little beauties on eBay:

[Image: file-60.jpg]

They're designed to go on the sides of the front bumper to allow air to be fed into the inner arch liners. These are ideal for the plans I have to relocate my induction kit and feed the engine cooler, denser air, thus hopefully yielding a bit more power.
It'll also provide me a solution for removing the pesky MAF sensor which is no longer used.

This what it'll look like mocked in place with a little bits double sided sticky take. It was important to get the location right - not only because I didn't want them looking out of place but also because I plan on ducting the air and want to make sure that the ducting doesn't collide with anything behind the bumper.

[Image: file-61.jpg]

It turns out that the intercooler pipework is in the way of my plans so I set about re-manufacturing it. Most people would think twice about taking a chop-saw to their HKS intercooler kit but needs must...
As you can see from the picture below, the original route for the HKS pipe work runs straight through the middle of the void where the standard air box used to be.

[Image: file-62.png]

I need to move the whole assembly towards the front of the vehicle to allow enough room for a new induction system.

Shaun TDI
Junior Member

07-09-2018, 06:15 AM

#14

You can see from the image that I've already placed the filter head inside the inner arch. This is roughly where the final fitment will be.

With the bumper off and the scoops mocked into place, I decided that the best way of securing them would be a series of small counter-sunk cap head bolts. I had these available in anodised black so they'd be practically invisible from anything more than a few feet away. These were then bolted from the back with washers and a small amount of thread-lock to secure them.

[Image: file-64.jpg]

At this point I was ready to start porting a whole in the bumper to allow the air-flow as required. Too late to turn back now as the holes had already been drilled!
Using a power file, the hole was made to the same size as the reverse side of the scoop and then a special sealant is used to fill the gaps to prevent any water sitting in the small recesses.

[Image: file-65.jpg]

Now that its fitted, the air is allowed to fill the air liner area.

[Image: file-66.jpg]

The next step is to make a ducting system for the reverse side so that the air gathered by the scoop is directed straight at the filter head.
The final external result with the bumper back on looks like this:

[Image: file-68.jpg]

Shaun TDI

07-09-2018, 06:15 AM #14

I ended up cutting the feed side into several section to allow enough room for what I want.
The top section now looks like this with an extended portion, using reinforced silicon hosing.

[Image: file-63.jpg]

You can see from the image that I've already placed the filter head inside the inner arch. This is roughly where the final fitment will be.

With the bumper off and the scoops mocked into place, I decided that the best way of securing them would be a series of small counter-sunk cap head bolts. I had these available in anodised black so they'd be practically invisible from anything more than a few feet away. These were then bolted from the back with washers and a small amount of thread-lock to secure them.

[Image: file-64.jpg]

At this point I was ready to start porting a whole in the bumper to allow the air-flow as required. Too late to turn back now as the holes had already been drilled!
Using a power file, the hole was made to the same size as the reverse side of the scoop and then a special sealant is used to fill the gaps to prevent any water sitting in the small recesses.

[Image: file-65.jpg]

Now that its fitted, the air is allowed to fill the air liner area.

[Image: file-66.jpg]

[Image: file-67.jpg]

The next step is to make a ducting system for the reverse side so that the air gathered by the scoop is directed straight at the filter head.
The final external result with the bumper back on looks like this:

[Image: file-68.jpg]

Shaun TDI
Junior Member

07-09-2018, 06:26 AM

#15

I'm hoping that when I get it back on the dyno, there is a measurable difference. After letting it run for a while last night, the induction noise has definitely changed. The turbo whistle is more prominent and the overall induction noise seems to 'boom' a little in the wing. From inside the car, it sounds roughly the same but I haven't had the opportunity to give it some stick yet.

Watch this space!!

Shaun TDI

07-09-2018, 06:26 AM #15

The last 3 pieces for the induction system arrived yesterday so last night I stayed late and finished it off.

Most of the intake used to be a horrible plastic corrugated affair, but now its been replaced with smooth mandrel bent pipe work.

[Image: file-69.jpg]

[Image: file-70.jpg]

[Image: file-71.jpg]

[Image: file-72.jpg]

I'm hoping that when I get it back on the dyno, there is a measurable difference. After letting it run for a while last night, the induction noise has definitely changed. The turbo whistle is more prominent and the overall induction noise seems to 'boom' a little in the wing. From inside the car, it sounds roughly the same but I haven't had the opportunity to give it some stick yet.

Watch this space!!

Shaun TDI
Junior Member

07-09-2018, 06:27 AM

#16

Last night was test night...
Needless to say, the induction changes have worked.
[Image: file-73.jpg]

After the first power run, it was obvious that the intake system was working. The car was instantly running lean as soon as it came up on boost. So much so that the injectors are now maxxed out a lot earlier than predicted and my maximum boost level is only 1.2bar.
My previous level of 1.35bar gave me a total power of 316.5bhp and 276ft/lbs (at the hubs)
with this in mind, I was entirely expecting a decrease in power. I have collated over 100 dyno runs on my car since I bought it so I back-tracked through the files to find the last dyno run performed at 1.2bar.
This dyno run revealed that at 1.2bar, I had 306.5bhp & 281.3ft/lbs of torque.
[Image: file-74.jpg]

With maximum boost now pegged at 1.2bar and the induction kit working well, we proceeded to see what increases we could find.

The intake air temperatures NEVER ONCE got above 14 degrees centigrade - the most pleasing thing about this fact is that the ambient temperature within the test cell was also 14 degrees centigrade! This proves that at no point was the engine breathing air from within the engine bay or any external heat source. Top Result!

Because the engine was now breathing colder denser air, we could re-calibrate the ignition values to suit. Below is a graph showing the before and after differences demonstrated by the effectiveness of the intake changes.
[Image: file-75.jpg]

337.5bhp @ 6440rpm AT THE WHEELS
304.2ft/lbs of torque @ 4710rpm AT THE WHEELS

Shaun TDI

07-09-2018, 06:27 AM #16

Last night was test night...
Needless to say, the induction changes have worked.
[Image: file-73.jpg]

After the first power run, it was obvious that the intake system was working. The car was instantly running lean as soon as it came up on boost. So much so that the injectors are now maxxed out a lot earlier than predicted and my maximum boost level is only 1.2bar.
My previous level of 1.35bar gave me a total power of 316.5bhp and 276ft/lbs (at the hubs)
with this in mind, I was entirely expecting a decrease in power. I have collated over 100 dyno runs on my car since I bought it so I back-tracked through the files to find the last dyno run performed at 1.2bar.
This dyno run revealed that at 1.2bar, I had 306.5bhp & 281.3ft/lbs of torque.
[Image: file-74.jpg]

With maximum boost now pegged at 1.2bar and the induction kit working well, we proceeded to see what increases we could find.

The intake air temperatures NEVER ONCE got above 14 degrees centigrade - the most pleasing thing about this fact is that the ambient temperature within the test cell was also 14 degrees centigrade! This proves that at no point was the engine breathing air from within the engine bay or any external heat source. Top Result!

Because the engine was now breathing colder denser air, we could re-calibrate the ignition values to suit. Below is a graph showing the before and after differences demonstrated by the effectiveness of the intake changes.
[Image: file-75.jpg]

337.5bhp @ 6440rpm AT THE WHEELS
304.2ft/lbs of torque @ 4710rpm AT THE WHEELS

Shaun TDI
Junior Member

07-09-2018, 06:28 AM

#17

I cannot stress enough how important it is on a Subaru (or any other turbo charged car for that matter) that you give it colder denser air.
Previously, it'd been consuming warm air from the coolant radiator, engine block, exhaust manifold - anything it could get its hands on.

Purely from a numbers point of view, I've seen a gain of 12% from doing this! I defy anyone to try and disprove that air density is the key to making good, solid, reliable power.
How many other 2.0ltr engines do you know of that make 337.5bhp (405.0bhp at the flywheel accounting for an average of 20% transmission losses) but only run 1.2bar...

The three magic words are EFFICIENCY EFFICIENCY EFFICIENCY.

Aside from the removal of the interior and the installing of a 13 point roll cage, this pretty much brings the build up to date.

Shaun TDI

07-09-2018, 06:28 AM #17

Shaun TDI
Junior Member

07-09-2018, 06:29 AM

#18

Things are about to get a little more interesting...
Arrived this morning:
[Image: Pic001-3.jpg]

Deatschwerks 850cc injectors.
Money I didn't want to spend but didn't have a choice. Based on the projected flow data from the alterations I've had made to my exhaust manifold and up-pipe, my old injectors would be running at about 120% duty cycle.
The only other option would be to turn the boost down to around 0.7bar but I cant do that because the minimum pressure that my actuator allows is 0.85bar
The manifold and up-pipe should be here this afternoon.

Shaun TDI

07-09-2018, 06:29 AM #18

Things are about to get a little more interesting...
Arrived this morning:
[Image: Pic001-3.jpg]
[Image: Pic002-2.jpg]
Deatschwerks 850cc injectors.
Money I didn't want to spend but didn't have a choice. Based on the projected flow data from the alterations I've had made to my exhaust manifold and up-pipe, my old injectors would be running at about 120% duty cycle.
The only other option would be to turn the boost down to around 0.7bar but I cant do that because the minimum pressure that my actuator allows is 0.85bar
The manifold and up-pipe should be here this afternoon.

Shaun TDI
Junior Member

07-09-2018, 06:30 AM

#19

Old vs. New side by side. You can see the difference straight away.

[Image: IMG_7295.jpg]

As you can see, the internal bore was shocking on the old pipe (left) at just 1.75 inches in diameter. The new pipe measures 2.5 inches, tapering only slightly as it reaches the turbo charger.

[Image: IMG_7297.jpg]

This is the end that meets the turbo. The flange was cut off the old pipe and re-used then bored out.

[Image: IMG_7287.jpg]

The best bit - a V-Band clamp which doesn't rely on your typical gasket arrangement. No gasket means no gasket leaks!

Shaun TDI

07-09-2018, 06:30 AM #19

mmmmmmmm - check out my sexy new exhaust components!

The old up-pipe and collector were thought to be restrictive due to their internal size and shape so with a touch of maths, common sense and voodoo, we've come up with this little beauty...

[Image: IMG_7296.jpg]
Old vs. New side by side. You can see the difference straight away.

[Image: IMG_7295.jpg]
As you can see, the internal bore was shocking on the old pipe (left) at just 1.75 inches in diameter. The new pipe measures 2.5 inches, tapering only slightly as it reaches the turbo charger.

[Image: IMG_7297.jpg]
This is the end that meets the turbo. The flange was cut off the old pipe and re-used then bored out.

[Image: IMG_7287.jpg]
The best bit - a V-Band clamp which doesn't rely on your typical gasket arrangement. No gasket means no gasket leaks!

Shaun TDI
Junior Member

07-09-2018, 06:31 AM

#20

Well,

I'm not gonna say that I'm good at what I do or that I know what I'm doing but needless to say, the exhaust redesign is working a treat!

I've gone from 337bhp to 365bhp by removing the flow restrictions and also gain another 15ft/lbs of torque.
Boost remains virtually the same at 1.35bar

Get In!!