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Jay Bamrah

Is anyone forced induction and still passing emissions tests legitimately?

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Hey

Just curious but does anyone here have a turbo or supercharged BRZ/86 that passes emissions legitimately or is it a given that you won’t pass legitimately. I guessed with a supercharger you can keep the cats. Lesser so with a turbo due to they need a more free flow exhaust but i don’t know for sure.

Also will stock 7inch wide tyres + MP4 tyres be adequate grip or not really.

Any help is appreciated thanks:)

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Supercharger in most cases, as sitting on intake side, doesn't affect normally exhaust side, where both cats are, unlike turbo, that needs at very least modified headers (where primary stock cat is) to put snail to spool in. So i guess, there shouldn't be much problems with emissions in normal SC build.

Though many installing SC may also change exhaust, mostly for sound change i guess.

"free flow" might be overstated. Stock or upto 2.5" exhaust piping should be sufficient for rather high power builds.

I'd rather invest in strengthened transmission bits, at very least clutch. Alternative gearboxes and adapters for them might be on expensive side. Well, one can always not aim for too high of power, which will reduce load & wear on transmission, to reduce not only budget for engine build, but also lessen need to upgrade many transmission components aswell. Imho that was one of reasons for Cossy to not make their SC kit too powerful. My own choice still stands with staying NA, as it keeps car spendings low.

MP4 is much grippier then stock primacies. Hmm, will it be "enough"? Depends on subjective feel/driving style/expectations aswell. But if you wanted to save on tire side .. not sure it's worth it. Relative budget on tires will be small fraction from all the costs in proper & reliable FI build imho (unless you'll go for modest gains route, similar to mentioned Cossworth kit).

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9 hours ago, Jay Bamrah said:

Hey

Just curious but does anyone here have a turbo or supercharged BRZ/86 that passes emissions legitimately or is it a given that you won’t pass legitimately. I guessed with a supercharger you can keep the cats. Lesser so with a turbo due to they need a more free flow exhaust but i don’t know for sure.

Also will stock 7inch wide tyres + MP4 tyres be adequate grip or not really.

Any help is appreciated thanks:)

My car has passed an MOT emissions test with a supercharger and just the secondary cat.  So if you were to go turbo, that should also pass emissions.  The issue with only one cat is getting the secondary cat hot enough, which a turbo/SC will help with.  You shouldn't need a new exhaust unless you're going for very high power, at which point you'd be looking at strengthening the engine's internals - you will most likely need forged rods before you need a higher flowing exhaust.

In terms of enough grip, Michelin PS4 (I guess that's what you mean) are very good.  Someone was actually running SC with the stock Primacy tyres, which seems like madness to me and was probably enough to focus the attention when it's cold and wet.  I'm on slightly wider PS4, and there is plenty of grip.  The big advantages I've found with PS4 are better wet/cold weather performance, and a more progressive feel when they start losing grip; the feel through them is far better than the Primacy tyres that (to me) always felt like there was a very fine line between on the limit and over the limit.  I'd be happy to run SC with stock wheels on PS4.

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As @Church said, if you buy a supercharger and keep the stock exhaust system you should legally pass the emissions test without issue. You can get away with changing the catback and still be legal. It's when you start changing exhaust manifold & front pipe is when you'll have problems.

From a legal point the car needs to be as it left the factory or with an OEM spec equivalent part. In the case of our cars, they have two catalytic converters if you remove one of them it's technically no longer compliant and therefore should be an instant fail.

Now the grey area is, you could have a decat exhaust manifold but the stock front pipe (vice verse) and then pass the emissions test. This isn't legal as you've still removed a cat, but if the MOT tester can't see the decat and you've passed the emissions, they'll mark it down as a pass anyway. 

As for turbo kits, the majority don't have catalytic converters fitted to them and I can only think of 4 turbo kits that do an option for a catted version, these are:

Works Turbo Kit
HKS Turbo kit
Blitz turbo kit
MPS Engineering 

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28 minutes ago, spikyone said:

My car has passed an MOT emissions test with a supercharger and just the secondary cat.  So if you were to go turbo, that should also pass emissions.  The issue with only one cat is getting the secondary cat hot enough, which a turbo/SC will help with.  You shouldn't need a new exhaust unless you're going for very high power, at which point you'd be looking at strengthening the engine's internals - you will most likely need forged rods before you need a higher flowing exhaust.

In terms of enough grip, Michelin PS4 (I guess that's what you mean) are very good.  Someone was actually running SC with the stock Primacy tyres, which seems like madness to me and was probably enough to focus the attention when it's cold and wet.  I'm on slightly wider PS4, and there is plenty of grip.  The big advantages I've found with PS4 are better wet/cold weather performance, and a more progressive feel when they start losing grip; the feel through them is far better than the Primacy tyres that (to me) always felt like there was a very fine line between on the limit and over the limit.  I'd be happy to run SC with stock wheels on PS4.

Thanks a lot!

What supercharger do you have and aftermarket manifold?

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Hello Jay

 

My car passes emissions test legitimately at my Toyota dealership.  I have second cat delete pipe, but the OEM exhaust manifold (with primary cat) still in place.  I did drive around on the original primacies and alloys for a while, and under most circumstances they were okay, but under hard acceleration from standstill I could easily fishtail with a nasty smell.  Since uprating wheels and tyres I have had no traction problems.  

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6 minutes ago, will300 said:

As @Church said, if you buy a supercharger and keep the stock exhaust system you should legally pass the emissions test without issue. You can get away with changing the catback and still be legal. It's when you start changing exhaust manifold & front pipe is when you'll have problems.

From a legal point the car needs to be as it left the factory or with an OEM spec equivalent part. In the case of our cars, they have two catalytic converters if you remove one of them it's technically no longer compliant and therefore should be an instant fail.

Now the grey area is, you could have a decat exhaust manifold but the stock front pipe (vice verse) and then pass the emissions test. This isn't legal as you've still removed a cat, but if the MOT tester can't see the decat and you've passed the emissions, they'll mark it down as a pass anyway. 

As for turbo kits, the majority don't have catalytic converters fitted to them and I can only think of 4 turbo kits that do an option for a catted version, these are:

Works Turbo Kit
HKS Turbo kit
Blitz turbo kit
MPS Engineering 

Thankyou! 

I have a catless manifold NA tune from TUning developments and I’m at the stage of just researching/deciding if I want to go turbo or supercharged, I would prefer be able to pass mot legitimately which is why I ask. That first then 2nd is reliability 3rd is cost.

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1 minute ago, Subota Boy said:

Hello Jay

 

My car passes emissions test legitimately at my Toyota dealership.  I have second cat delete pipe, but the OEM exhaust manifold (with primary cat) still in place.  I did drive around on the original primacies and alloys for a while, and under most circumstances they were okay, but under hard acceleration from standstill I could easily fishtail with a nasty smell.  Since uprating wheels and tyres I have had no traction problems.  

Hey, thankyou.

I see your profile photo is a Cosworth supercharger. Am I right to assume you have the decatted front pipe, stock manifold and a Cosworth super charger?

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1 minute ago, Jay Bamrah said:

Thankyou! 

I have a catless manifold NA tune from TUning developments and I’m at the stage of just researching/deciding if I want to go turbo or supercharged, I would prefer be able to pass mot legitimately which is why I ask. That first then 2nd is reliability 3rd is cost.

Well technically you not currently legal anyway. 😂

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7 hours ago, Church said:

Supercharger in most cases, as sitting on intake side, doesn't affect normally exhaust side, where both cats are, unlike turbo, that needs at very least modified headers (where primary stock cat is) to put snail to spool in. So i guess, there shouldn't be much problems with emissions in normal SC build.

Though many installing SC may also change exhaust, mostly for sound change i guess.

"free flow" might be overstated. Stock or upto 2.5" exhaust piping should be sufficient for rather high power builds.

I'd rather invest in strengthened transmission bits, at very least clutch. Alternative gearboxes and adapters for them might be on expensive side. Well, one can always not aim for too high of power, which will reduce load & wear on transmission, to reduce not only budget for engine build, but also lessen need to upgrade many transmission components aswell. Imho that was one of reasons for Cossy to not make their SC kit too powerful. My own choice still stands with staying NA, as it keeps car spendings low.

MP4 is much grippier then stock primacies. Hmm, will it be "enough"? Depends on subjective feel/driving style/expectations aswell. But if you wanted to save on tire side .. not sure it's worth it. Relative budget on tires will be small fraction from all the costs in proper & reliable FI build imho (unless you'll go for modest gains route, similar to mentioned Cossworth kit).

Hey thanks!

So you believe supercharger would help with the emissions test but also believe that I will need to upgrade my transmission? 
 

I was going to get a new clutch and flywheel or just clutch with the Kit anyway but I was hoping at 250-280HP that would be enough for my car to still be reliable?

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2 minutes ago, will300 said:

Well technically you not currently legal anyway. 😂

😂😂true technically but il pass the MOT and my exhaust is very quiet so I won’t get checked by police so I’m okay 😂

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47 minutes ago, Jay Bamrah said:

Hey thanks!

So you believe supercharger would help with the emissions test but also believe that I will need to upgrade my transmission? 
 

I was going to get a new clutch and flywheel or just clutch with the Kit anyway but I was hoping at 250-280HP that would be enough for my car to still be reliable?

Standard clutch, flywheel, gearbox, engine are all absolutely fine if you stay below 300bhp.

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2 minutes ago, ThatGuyThere said:

Standard clutch, flywheel, gearbox, engine are all absolutely fine if you stay below 300bhp.

Yeah that’s what I thought too from my research! but everyone’s experience is different so if he experienced problems at sub 300hp then it definitely would put me off a bit

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Ill talk you through when we meet but in summary:

1. You can potentially pass MOT with one Cat but not legally.  Different as you know. Mine failed with only second cat on TD manifold. Its not a gaurantee, remember, its likely based on CAT temp and its health. CATS go down with age and usage , so you cannot fully trust this unless you have both CATS.

2. You might need supporting mods but not definitely as each car is different. Some clutches fail at 270 bhp while others hold up till 300. Things that are under consideration should be Clutch, Fuel Pump, Injectors, Tyres (Brake atleast pads and discs) or BBK. So they are nice to do alongside. Some people also want Temp/ Boost gauges etc to ensure they always keep a tab on the vital parameters. 

3. With Turbo, as Will pointed out, very few kits remain that can let you have both CATS intact and AFAIK, over a year or two, your CAT will degrade, so it will not hold on long term.

It is a bit of a slippery slope in terms of cost unfortunately and you need to be ready for supporting mods sooner or later.

 

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3 hours ago, Jay Bamrah said:

Thanks a lot!

What supercharger do you have and aftermarket manifold?

Harrop supercharger and Rogue Motorsport EL manifold.  I previously had the Tuning Developments manifold.  Martin on here had his Harrop fitted with his existing TD manifold a few months before me and was concerned the engine bay was getting a bit hot, as the TD manifold loops up into the bay, so he switched to the Rogue manifold around the time I booked in to get the SC fitted.  I saw his pictures and got serious manifold envy, so I ended up going the same route.

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2 hours ago, Lmc said:

My car is running 290bhp on tuning developments turbo kit. The stock clutch lasted about 5 minutes before it started slipping.

Damn it says you live in Devon, that’s one hell of a distance to travel haha. Yeah as I have the TD NA kit this was my obvious choice, also mike is such a nice guy I trust his work.

I like the idea of low down torque from a super charger and that I can keep my cat without it being a limitation so much but idk. So many things to think about 

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16 minutes ago, spikyone said:

Harrop supercharger and Rogue Motorsport EL manifold.  I previously had the Tuning Developments manifold.  Martin on here had his Harrop fitted with his existing TD manifold a few months before me and was concerned the engine bay was getting a bit hot, as the TD manifold loops up into the bay, so he switched to the Rogue manifold around the time I booked in to get the SC fitted.  I saw his pictures and got serious manifold envy, so I ended up going the same route.

That’s a lot of money to change manifolds when u have one already did you not find a better option ?

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2 hours ago, Lmc said:

My car is running 290bhp on tuning developments turbo kit. The stock clutch lasted about 5 minutes before it started slipping.

How’s everything else holding up  how many miles have u done with it and how many miles does ur car have?

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14 minutes ago, Jay Bamrah said:

That’s a lot of money to change manifolds when u have one already did you not find a better option ?

I suppose it depends what you mean by better.  I take my car on track so under-bonnet temperatures were more of a concern, and seeing Martin's comments on his thread I felt that there would be a benefit in swapping.  I also had the same issue where the TD manifold was tight against the front of the engine.  No issues and when I asked Mike at TD about it he said it was normal, but having it out of the way felt like a benefit.  I also thought the Rogue looked nicely engineered.  I still need to get around to selling my TD manifold too, which should recoup some of the cost.  Since it was done at the same time as the SC and some other work the cost was less noticeable.

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5 hours ago, Jay Bamrah said:

Hey, thankyou.

I see your profile photo is a Cosworth supercharger. Am I right to assume you have the decatted front pipe, stock manifold and a Cosworth super charger?

You are indeed correct.  Looks like this.

 

DSCN2146_zpso5usabwc.jpg

 

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42 minutes ago, spikyone said:

I suppose it depends what you mean by better.  I take my car on track so under-bonnet temperatures were more of a concern, and seeing Martin's comments on his thread I felt that there would be a benefit in swapping.  I also had the same issue where the TD manifold was tight against the front of the engine.  No issues and when I asked Mike at TD about it he said it was normal, but having it out of the way felt like a benefit.  I also thought the Rogue looked nicely engineered.  I still need to get around to selling my TD manifold too, which should recoup some of the cost.  Since it was done at the same time as the SC and some other work the cost was less noticeable.

If you didn’t track your car would you still have done it? Also that thread had a lot of useful info thanks for that!

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30 minutes ago, Subota Boy said:

You are indeed correct.  Looks like this.

 

DSCN2146_zpso5usabwc.jpg

 

Just curious how much power do you have with a stock manifold and supercharger do you have a Dyno graph?

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It may seem not like big gains regarding bhp (IIRC it was something like 240 or 260bhp?), but, what actually is felt by driver, more gains for torque (obviously also filling well torque dip). And mild gains overall do well for not needing doubling or tripling modding budget for accompanying mods, as stock components do sufficiently well. Slight pity that Cossy stopped selling this kit. Some other kits may claim higher gains, but this seemed well thought out compromise for simplicity/reliability.

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