GTI 6 Inlet Manifold in 1.8

[MiiTCH]

Are these conversions worth it? I've been thinking about doing it but not too sure if its worth it?

Is there any noticable difference once it has been done? Ive also noticed that the standard air box wont fit once the GTI manifold is fitted, so everyone seems to use cone filters, but are there any ways of being able to keep an air box on it? such as one from a GTI 6?

[Ed Doe]

Search for Nialls 'project craig'

In short the gti inlet is too big, and the tb twice the size as the 1.8s too, and the ecu is crap and throws a wobbler causing running issues, overfuelling and eventually wrecks the engine.

C.A.R is another who will agree.

If you're gonna mod the 1.8, do it properly and get a stand-alone ecu. Most won't bother with this as they want a 'cheap bolt-on mod' rather than spend the money, but that's the only way you'll get it working right.


/thread

[Scott]

There's a guide here: <!-- l --><a class="postlink-local" href="http://www.306oc.co.uk/forum/viewtopic.php?f=31&t=174" onclick="window.open(this.href);return false;">viewtopic.php?f=31&t=174</a><!-- l -->

But as said, there are a fair few people who have fitted it, and there do seem to be mixed results. Long term it doesn't seem to be worth it.

[Grant]

I would beg to differ ed. not saying your incorrect, but plenty of people have done this mod without complication.
This whole subject has been debated before so I'm not goin to open an old wound. In short; you can fit a '6 inlet, but you will need either a cone filter of '6 airbox. The long term effects are a grey area with no concrete evidence for either argument, but it does improve the breathing of the engine considerably.

Oh and it sounds epic!

[4WayDiablo]

i do remember being drunkenly thrown around in the back of nialls car thinking f*ck me it sounds good lol

[Scott]

i do remember being drunkenly thrown around in the back of nialls car thinking f*ck me it sounds good lol

Out of context quoting ftw

[4WayDiablo]

Oh and it sounds epic!

i do remember being drunkenly thrown around in the back of nialls car thinking f*ck me it sounds good lol

[Grant]

Coventry Xmas meet? Epic lol's!!!

[Ed Doe]

I don't have any 1st hand experience with this ill admit, but Nialls is the 3rd 1.8 project thread I've read where a gti inlet manifold was fitted to a 1.8, which subsequently threw a shitfit, had the exact same overfuelling problems and then got sold/broken.

There was Adam's green 5dr 1.6 which he put a 1.8 into, which then died and was broken, CARs, which had overfuelling followed by borewash which was then sold and probably broken, and Nialls, which I'm sure he'll fix, but currently is broken with the same as the above...

[Grant]

Granted there are mixed results with this.
IIRC car was running the gti FPR and/or gti injectors. Causes over fuelling problems.
Niall doesn't know the source of his problem yet, and was working fine for a considerable amount of time with the fanny mould fitted.
Mine is runnin fine at the moment. Touch wood lol.

Like I say it's all been slogged out before, with no definitive evidence for either argument. I think it's just a case of fit and see how you get on with it.

I have been looking at wideband lambada as a precaution as mine is ending its life cycle, so may fit one for peace of mind.

[Niall]

I would like to say my running issues are not down to the inlet after a chat with a ECU specialist today.
The 1.8 Sagem ECU suffers from being spiked by broken down coils. The best thing that can happen is it wrecks the ECU completely causing a non start - new ECU required.
Or what also happens is it blows several components in the ECU causing overfuelling, misfires, hesitation ect. You can replace every single sensor and you will still get these results.
My car is running the original ECU and original Sagem coil pack - both potentially faulty devices.
I still don't think the inlet has caused any issues and I did do a lot of looking into if the car can take it before I fitted it (I have a copy of the map on my computer somewhere!) and it should handle it fine. Only problem being is if something does go wrong, mainly lambda and map, it does throw a fit big style as the sensors are already on their limits with the manifold under normal conditions.

[Niall]

i do remember being drunkenly thrown around in the back of nialls car thinking f*ck me it sounds good lol

Never thought I would hear you say something good about a perv. Need to hear it with its new exhaust

[4WayDiablo]

i do remember being drunkenly thrown around in the back of nialls car thinking f*ck me it sounds good lol

Never thought I would hear you say something good about a perv. Need to hear it with its new exhaust

Eh? I've always said I would have a petrol. And tell you want if someone offered me good money for my car I would be straight out buying an Astor 6 or rallye tbh
All the other petrol engines are a bit pointless when you can get 150 out of a derv easy lol
Only my opinion though.

[lewisdmz]

Has anyone had a before and after RR to see how much difference this makes?

[Niall]

Has anyone had a before and after RR to see how much difference this makes?

Mine will be RR'd at fcs but it's also had other work. Iirc you get two runs at fcs so I might do one with the gti and 1 with the 1.8

[darrenjlobb]

Provided you use all the sensors / injectors etc from the orignal motor, I cant really see how it will do any harm tbh, its not going to make a big enough difference to put sensors out of range id not have thought, but then what do I know about petrols...

But just sounds like a typical ladygarden forum rumour thats probs not entirely true, or at least not at root....

[Niall]

Provided you use all the sensors / injectors etc from the orignal motor, I cant really see how it will do any harm tbh, its not going to make a big enough difference to put sensors out of range id not have thought, but then what do I know about petrols...

But just sounds like a typical ladygarden forum rumour thats probs not entirely true, or at least not at root....

Exactly this. Most of the bad mouthing about it came from cars car who used gti injectors (somive been told) and then people (well toms306) spread rumours.
1.8s are known for their ecus going bad and like mine, can overfuel, hesitate and run like shit!

[lewisdmz]

Has anyone had a before and after RR to see how much difference this makes?

Mine will be RR'd at fcs but it's also had other work. Iirc you get two runs at fcs so I might do one with the gti and 1 with the 1.8

That would be a good idea, I imagine you'd need to drive around for a bit with after the switch over though as won't the ECU need to 're-learn' stuff. Or is that another myth?

[Niall]

Parade lap

[Eeyore]

Ok ill throw in my experience. Carl Chambers fitted mine about 4 months ago now. It sounds bloody epic and i havent really had any problems apart from leaky fuel lines but they just need nipping up every now and again. If you do it make sure the fuel line is rated for fuel and is not this coloured bs that wont withstand being under pressure.

I have however had one rather large problem of overfueling which resulted in a 260 mile journey costing £120. This turned out to be a faulty MAP sensor which when disconnected fixed the over fueling. I then got another one for a few quid from the scrappers off another 1.8. The idle sometimes gets stuck between 1 and 2k however i think this may be a dodgey idle control valve. Investigations continue.

I still beleive that the gti manifold is a great mod for the 1.8 however you would need a remap to use its full potential and then because the 1.8 ecu is a sagem (which is gay) then you cant remap it so need to get a standalone ecu.

In the future i am looking to get a gti6 exhaust manifold fitted which requires either dropping the sub frame or tilting the engine forwards. I have been quoted £100 for this and i got the full gti6 exhaust system for £40.

I got the gti6 manifold for £30 and it cost £40 to fit. You will need the manifold with all the sensors and a gti6 fuel rail. You will not need the gti6 injectors (unless remapping) as they deliver more fuel than what the ecu thinks and thus this is where all of the over fueling problems in the past have come from!

[Eeyore]

Has anyone had a before and after RR to see how much difference this makes?

ill probably put mine on the RR at FCS. It was 108.1 a few months ago and nothing else has changed since. Ill maybe add a straight through centre section but that shouldnt change it that much.

[Toms306]

:o I don't spread rumours niall...I hadn't even commented here yet!
Firstly is agree Sams sounds awesome and the shiny metal mani looks better in the bay.

I d also agree its the gti injectors that cause problems BUT, like any mod,I think it can break sensors and stuff that was on its last legs anyway.

It doesn't add much power tbf, maybe 5-10bhp as a very rough guess, but nowhere near xsi speed if that's what you wanted. (gauging from me and Sam on the a12 lol)

[Grant]

Sam all those problems you have listed are not in relation to the actual manifold itself. The sensors could have gone on any manifold. And increase in airflow will not kill sensors.

And I agree that a remap is needed to reach its full potential, but going through the expense of a remap just for an inlet manifold seems expensive and not worth it in my books. Maybe shove some cams and decat in the mixture too along with the 6 injectors and for if you ate going to get a remap.

[Ruan]

The problem is right, you have to think how the ECU works...

Well what inputs does it have:

- MAP - Manifold pressure
- TPS - Throttle Position
- Lambda - Exhaust O2 Content
- CLT - Coolant Temperature
- CPS - Cam Position Sensor
- CAS - Crank Angle Sensor

They're essentially all the inputs for one of these engines - then you look to how the ECU calculates what mixture to give the engine - it looks at the RPMs deduced by the CAS and CPS - knowing that it can also know when to fire the spark and Injectors (I'm 99% sure the injectors on 1.8s are Semi-Sequential)... It then looks at the Throttle Position and MAP - essentially MAP and Throttle Position read the same value, it's just for transients where the manifold is filling or emptying where the TPS is used over MAP, then it looks at Lambda - which is ONLY for part throttle correction, it will do NOTHING on full throttle and then uses CLT to simply enrich the mixture at low coolant temps...

The 1.8 MAY have an IAT sensor, but I'm not 100%, so if it does, it'll compensate if it's hot out...

The ECU does NOT know how much air is going intoand out of the engine, it can correct itself at part throttle on the Lambda, that's for cruising economy, not to mention it doesn't work when cold and not at full throttle...

How does the ECU know how much air is going into the engine - well that's your volumetric efficiency table - VE - that is HARD CODED into the ECU - VE being if there was NO restrictions on filling the cylinders (so the full 450cc being drawn in per stroke) being 100%, how many percent is ACTUALLY being drawn in - on a 1.8, somewhere in the reigon of 80% at peak torque, obviously this changes versus RPM and throttle position... Therefore it knows how much air *SHOULD* be going into your engine, there's no feasible way that the ECU can possibly know in actuality how much air is going in... If everything is left as standard, the ECU has a damned good idea knowing MAP, TPS and RPM how much air actually is going into the engine...

Once it knows how much air is going in, it can then see what the required mixture should be, it then throws in the correct mixture once going through the Lambda and CLT sensors and correcting it slightly for that...

So essentially - there is no way the ECU knows how much air is going into the engine, it hasn't a clue - now if you had a MAF sensor shoved on the end of it, it can then tell - that's how things like MR2 turbos, you can turn up the boost and they'll make 350hp on stock management... A non-MAF ECU hasn't a clue! That's not taking into account the spark calculations for adjusting ignition timing, that's pretty much set as it is, and won't change apart from on cold start...

This is why they need to be remapped, I'm not saying for a second that your ECU isn't shagged, Niall, it probably is, but bolting things to a Mafless ECU won't do anything - again another reason GTi6s don't improve power by bolting things on, they haven't a clue what's actually going on, just predefined values.

Sorry for the essay, but people are saying that the ECU will "learn" - it really won't, it'll learn a bit from the lambda at part throttle, but at WOT it can't do anything, it's hard coded in and there's no way of it correcting for more/less airflow.

[Grant]

Wow. Did you swallow every piece of technical data ever released by Peugeot?

Repped.

[Ruan]

Maybe.

[C.A.R.]

Basically just got the textbook response from Ruan above.

I've owned -
A 1.8 which I converted to GTi6 manifolds myself
A 1.8 Cab which was already converted, I turned it back to standard

In short, the pro's are-
Massively improved throttle response (this is due to the larger TB)
Noise (epic)
Looks more bling-er?

Con's -
Ruined MPG.
Flat spot at low RPM
Confused ECU, can cause EML to illuminate (more so on later cars especially)

The Cab 1.8 also had GTi6 cams. These made the car virtually no different to drive until you got near the rev-limiter. It would shove a little bit more power out but without the ability to raise the rev-limiter it was pointless.

If you have a 1.8 16v you have already got a great engine. Good, smooth powerband and incredibly reliable (bar a couple of sensors...) If I owned one today I'd add a stainless cat-back and a cone or panel filter and have done with it, as they are sweet-as-a-nut when standard. Once you can afford insurance, the cheapest thing to do is upgrade to a GTi6. Unless you can afford aftermarket management (£300+) and have access to someone or software that can map your car accurately.

[Ruan]

The thing is, the 1.8 is a BETTER engine IMO... The whole "Upgrade to a gti6" thing is pointless, you can get as good results, if not BETTER results with a 1.8... Rev it harder etc...

I'm just saying that the standard ECU cannot cope, but stick on a modified head/gti6/mi16/s16 head and then give it a darned good remap on proper management, you're sorted, it's an awesome engine base... As I said earlier, they're essentially a stroked down Mi16 with a pants head. But with all the advantages of being a short stroke...

The GTi6 isn't the be-all and end-all of performance french cars, there's so many other options out there, it may cost more, it may be a bit of ballache, but at the end you get something that's how YOU want it and not just "another gti6" and usually ends up better because of it.

[C.A.R.]

I don't disagree, but for costs' sake then a GTi6 is a fast-ticket to 167bhp out-of-the-box, and with prices of GTi6s hovering around £600-1200 you would struggle to justify the outlay for aftermarket management on a 1.8...

The same money spent on a GTi6 could see 180bhp+. Nicks' Rallye was just well-serviced, had a decat and magnex (I think) and a cone filter and pulled an impressive 182.2bhp on the rollers a few years back. For cost alone, you can't beat it.

Be thirstier though, I would imagine.

Still, here's to continuing to convince Niall to buy aftermarket management and an exhaust manifold with turbo flange, eh?

[Eeyore]

Sam all those problems you have listed are not in relation to the actual manifold itself. The sensors could have gone on any manifold. And increase in airflow will not kill sensors.

And I agree that a remap is needed to reach its full potential, but going through the expense of a remap just for an inlet manifold seems expensive and not worth it in my books. Maybe shove some cams and decat in the mixture too along with the 6 injectors and for if you ate going to get a remap.

never said it was due to the manifold. Just problems ive had since fitting it