MOT Mapping

[JamesArup]

Hey folks,

It's coming up to that time of year again, MOT time . And, unfortunately the "understanding" MOT guy that I used to use retired last year. So the chances of passing with no CATs and 600+ bhp are a solid 0. The new guy that took over from my old tester is having absolutely none of it. 

So I see that I have a couple of options:
 

• Source a couple of CATs, put them back in my system, and get it all remapped again. Although there's no guarantee that will actually solve the issue, and I have no idea where to find replacement CATs these days
   
• Get what I've heard referred to as an "MOT Map", where the car is mapped to run with the lowest emissions possible, just for the few minutes that it's being tested. 

Has anyone used the MOT Map method in the past, and where/who did you get to do it. I have a 6-speed Manual RZ-S, Single Turbo, Straight Through 4" HKS Titanium all running on a Syvecs S7i (full specs). My current mapping was all done over at Whifbitz, who have always been great, but it's a long way to go for me. I'm looking for someone local to Surrey, ideally near Surrey Rolling Road (for example) who can come out and do the map for me.

The various people I've used over the years (Ryan, for example) have all since moved on, so I'm a bit out of the loop with who's still in business. For those who are local to the South East area, I once sold an old turbo to a guy who worked inside Fairoaks Airport (Chobham), and he told me he had a Dynopack Dyno there. This was over a year ago now, and I can't find anything on Google, so just asking in case anyone local might know the place?

Anyway, hopefully that all made some sort of sense!
Thanks very much,

James

[ben_harmer32]

You are not that far from SRD. 

[Annabella]

Get some cats back in, as if the Cats aren't there it's an automatic fail now. Regardless of your Map. 

[Style]

4 minutes ago, Annabella said:

Get some cats back in, as if the Cats aren't there it's an automatic fail now. Regardless of your Map. 

This.

If the option of a friendly MOT tester is gone then you'll need at least 1 cat present on the car iirc. Even if the car passes on emissions, it'll fail without the physical presence of a cat.

[JamesArup]

Interestingly, not having CATs has never really caused much of an issue for me, even before I found the "friendly" tester. I've had the Supra for nearly 19 years, most MOT places I've been to seem to let the CAT issue slide, as long as the emissions are okay. They seem to be of the opinion that I could take those CATs out the moment I leave the test centre, and therefore it's not their problem. The emissions are more of an issue these days though because it's all computerised and logged on a database, so it's only since that came into effect that I've had problems.

Just in case I did go that route, is there a place to get CATs these days? I think I took mine out about 15 years ago, and no longer have them. Or is there an option to get a full exhaust system, front-to-back, with CATs included? I do love my HKS Ti, but it's very loud! I don't mind loud necessarily (I do less than 500 miles a year), but I prefer the more "throaty" Nur Spec-style sound these days

SRD does seem like the best option for me. I have used them over the years too, so perfectly happy with that. 

Thanks for the replies so far, much appreciated!
Cheers!

[mattdavies]

I think SRD could sort most of what you have listed, be it an exhaust with a Cat in or an MOT map. 

 

[rpslaughter1982]

I was looking at one if these for mot time. It says n/a but I'm pretty sure they're interchangeable 

https://www.cats2u.co.uk/home/6936-toyota-supra-30-01-93-12-96-catalytic-converter-bm90709.html

[welshbuddy]

get a sports cat welded into place? that can flow your bhp?

[Noz]

Get a cat fitted.

I plan to get a bypass valve for a car and silencer fitted. Mega expensive but friendly MOTs are only going to become harder and more difficult.

Make it switchable. Save yourself the long term worry.

[Noz]

I have an inline exhaust control valve anyway by the way, so pushing through an opened cat bypass would be possible with a second valve added.

[JamesArup]

On 10/23/2022 at 8:47 AM, rpslaughter1982 said:

I was looking at one if these for mot time. It says n/a but I'm pretty sure they're interchangeable 

https://www.cats2u.co.uk/home/6936-toyota-supra-30-01-93-12-96-catalytic-converter-bm90709.html

Hmm, this is interesting. Seems suspiciously cheap, I always figured that new CATs were going to cost significantly more. Although, as you said, these seem to be NA only and, if they will work on a TT, I'm sure they won't play nicely with my current 4" HKS Ti

Sports CAT sounds like a good idea, but not sure who does these at the moment. I've been looking around and all the articles I can find seem quite out-dated. I'm not too concerned about losing some power by having a CAT in place, and I'd need to get it all remapped either way. But would you get away with just 1 x CAT, or would you need to go back to the original 2 x CAT config?
 

12 hours ago, Noz said:

Get a cat fitted.

I plan to get a bypass valve for a car and silencer fitted. Mega expensive but friendly MOTs are only going to become harder and more difficult.

Make it switchable. Save yourself the long term worry.

This sounds expensive and complicated . I'm not 100% I understand how this would work. I've not actually ever had any feedback about the noise levels of the exhaust (and it's not quiet).

I think, ultimately, I might have to find a CAT to put in there to pass the "does it have a CAT" part of the test (regardless of emissions etc). And then get an MOT Map created that would satisfy the emissions part of the test (assuming that adding a single CAT still wouldn't pass the emissions with any of my existing maps). I plan to get in touch with SRD soon to discuss this, as the MOT is due in the first half of December, but you can do it up to 1 month earlier I believe.

Thanks for the all help so far!
Cheers

[Noz]

6 minutes ago, JamesArup said:

This sounds expensive and complicated . I'm not 100% I understand how this would work. I've not actually ever had any feedback about the noise levels of the exhaust (and it's not quiet).

I think, ultimately, I might have to find a CAT to put in there to pass the "does it have a CAT" part of the test (regardless of emissions etc). And then get an MOT Map created that would satisfy the emissions part of the test (assuming that adding a single CAT still wouldn't pass the emissions with any of my existing maps). I plan to get in touch with SRD soon to discuss this, as the MOT is due in the first half of December, but you can do it up to 1 month earlier I believe.

Thanks for the all help so far!
Cheers

Imagine you have a twin pipe setup that joins again at the final exhaust box. One would just have an inline valve in, the other section, smaller pipework, a cat and a silencer, also an inline valve in.

Smallerpipework would have an inline valve closed allowing full flow / noise. Main pipe closed valve, would divert flow to the smaller pipework, open inline valve on smaller pipework allow flow through the CAT.

I currently just have an inline exhaust control valve 4", the engine still runs and drives with it totally closed, but its massivel;y sluggish and the backpressure won't even allow the turbo to dump, the turbo also spools rapid, I know this because it whistles like hell when closed and driving.

Your proposal would solve your issue, but would still leave you vulnerable at a road side test. Probably never happen for 99% of us, I'm just trying to make mine totally legit.

[JamesArup]

Cool, that's what I figured it was. Does make a lot of sense, but I can imagine it's going to be expensive.

I my case, I live abroad and the Supra gets less than 500 miles a year on it. I think I would have to be considerably unlucky to have a roadside-check with the limited time I'm using it.

I was never stopped for any reason during my first 10 years of ownership whilst in the UK, so I'm willing to take that risk (I'll save this post for the future when I come crawling back after a roadside check )

Assuming the Cats2U link shared above isn't going to have a suitable CAT for my application, where should I be looking for a sports CAT? Are there Supra-specific ones, or are these the sort of things that you have to get custom made?

Thanks again!

[Mike2JZ]

There are only two aftermarket cat companies I would consider using parts from:

https://gsportbygesi.com/high-performance-catalytic-converters/g-sport-emissions-systems-products/

https://hjs-motorsport.de/en/products/motorsport

Both can be sourced via Evok3 or similar companies. You will require some custom fabication work to get this installed, no plug and play kits. If you are going to bother with a cat then you need to make sure it balances well with the rest of your setup. No point putting a tiny cat on a massive single turbo, as you will have issues. Likewise no point putting a massive cat on an NA that it cant heat up effieciently. 

Depending on your current power level, you can choose a large enough cat that will flow enough to not cause a flow restriction for most road cars, which means you can avoid having to do twin pipe systems with valves and lots of nonsense that will be a pain to maintain. In terms of packaging on a 3 or 3.5'' exhaust system, you can plum a cat in-line that will work with a Supra's underbody that will support around 850hp fairly comfortably. 

Once you want to go 1000hp+ with a cat, then the packaging of 4'' exhaust piping with a 5'' or larger cat becomes a bit of a problem and some creativity will be required, but most cars at this level are hardly road cars anymore, more race orientated so cats arent really high on the priority list. 

Interesting video that has some data on cat vs no cat. 

Another thing worth mentioning with cats is that its no good just putting one on the car and hoping for the best (although it will be better than nothing) Cats need to be at a certain temperature to do their job effectively, if they are too cold or too hot then they wont do much or can cause damage to themselves. They also need the correct ratio of air & exhaust gases to clean the waste air efficiently, and their placement in the exhaust system will have an affect on how easy it is to get them running efficiently. In an ideal scenario you would need a standalone ecu that can monitor Pre CAT AFR, Post CAT AFR, Pre CAT Temp, Post CAT Temp and have some dedicated strategies that will run in a closed loop function to maintain the cats efficiency during a multitude of different running conditions (Cold Start, Cruising, Deceleration etc...). A exhaust gas analyser will also be required whilst testing and setting up your systems as this will be whats used in most MOT/TUV centres to check the cat is working as effienctly as possible. 

The implementation of the above can be quite involved and not cheap to implement. Luckily the UK's MOT test is fairly basic so I wouldnt lose too much sleep over it. Some of the testing strategies in Europe for TUV is very involved and a bit harder than just holding an engine at 3000rpm for 30seconds and checking the gases being released. So hopefully it dosent become as stringent as that in the future, otherwise might have a harder task on our hands going forward. 

Ive never met anyone who's been stopped at the roadside and checked and penalized for lack of a cat in a Supra. I think most authorities think its just an old shitter, dosent have one anyway. I've been stopped in multiple countries in my supra and never had a cat and never had an issue. 

 

[JamesArup]

Thanks Mike, very detailed reply .

Those CAT prices are closer to what I expected. I would be needing one that does up to 850bhp I think (I'm around 620 right now). I guess they are all just universal applications, and you have figure out how/where to fit it yourself? My current system is 4", but I'm not against going down to 3-3.5" if it's going to make this whole process easier. I've had the HKS Ti on there for years now, and I'd be interested in something a bit more "throaty". The HKS is loud, and does sound good, but maybe a bit too loud at times. Although some of that might be due to having no CATs.

I've actually watched that video through before and it seems that, certainly for my usage, the CAT really won't have too much noticeable impact on the power/running of the car. 

I have a Syvecs S7i standalone ECU, so I am pretty sure that has all of the monitoring functionality needed to get everything set up and running as it should. Ideal scenario would be to get all of this sorted as cost-effectively as possible, and then simply not have to worry about it each year at MOT time. If that means a CAT + a specific MOT map, then fine, as switching maps is just a simple press of a button.

Certainly warrants more research at this stage, that's for sure!

Thanks again, appreciate all the help!