MGF inlet manifold swap to alloy from 135

[ashcapri28]

HI again all.

I'm looking to replace my plastic inlet manifold with an alloy inlet manifold I've got hold off from a 135 model MG TF.

The only problem that I have come across is that the alloy manifold has a combined map and air temperature sensor where as the plastic manifold has two separate sensors located in different positions on the manifold.

I have seen on other sites that the common thing to do is to tap and die a new hole / thread so you can use the original air temperature sensor

Is there any way to wire up to the dual purpose map/ air temperature sensor that's already there.

I realise I would need to plug from the 135 wiring loom then I believe you would have 4 wires from that plug / dual sensor, 2 wire for the map sensor and to wires for the in the air temperature.

I could be wrong about 4 wires maybe it's 3 wires, 2 signal ( 1 for the air temperature , 1 for the map sensor and then one ground )

is this right?

Is there a way to wire it up to an older system

W reg MGF steptronic mems 3

[ashcapri28]

Although my car is mems 3 it's one of the first released with mems 3 being steptronic therefore the inlet air temperature (green) sensor on air intake pipe cylinder 4 is wired up and not just a dummy/blank as fitted to later models.

Also is there anything else I need to know about?

I have heard that the diameter of the air intake pipes are larger than the intake on the head causing a step, is this true? A step is not good when we're talking about air flow performance

[ashcapri28]

Right scrub above I'm not going to replace my plastic manifold to an alloy one due to the step between the manifold and the head, air turbulence etc hampering performance I've also read that these guys using plastic manifolds swear they get round the track quicker.

Apparently from what I've read the 135 head is identical to the 120 head and it's the cams, throttle body and airbox changes that give the car few more ponies.

Whether it acceptable for the 135 engine or not I'm certainly not going to fit something that's inferior from a technical point of view.

[ashcapri28]

Typo in the above, the Lotus Elise guys swear that using their cars with plastic manifolds they get round there track quicker.

I would imagine that this step that you would get between the alloy manifold and inlet face would hamper torque if used on the 120 engine and bearing in mind that my engine/gearbox being a steptronic works at a continuous peak torque at full Throttle this would be a detriment to the car if I changed it to an alloy inlet manifold.

I would also suggest that the reason MG did not enlarge the ports on the 120 head when using it on the release of the 135 would be because it would make the car to close in performance to the 160. So in many respects that part, the head is detuned / restricted as part of their marketing strategy.

[RobboMC]

My understanding is that the valve springs are a bit tougher on the 135 to put up with the extra lift.
So it's not just a matter of popping a 135 cam and throttle body onto a 120 engine.

The 135 cams will fit, but I'd be worried about how long it might last.


But in effect it's all the same engine and the increase in horsepower comes from the different arrangements that are screwed on, like cams, vvc,
throttle bodies, injection and computer.

I'm no expert, but I think you'd be hard pressed to get 160 PS out of a K-series without vvc unless you seriously enlarged valves and inlets.

[ashcapri28]

Valve Springs probably are stronger due to the extra lift.

But reading your post I wasn't suggesting any of those things I can only assume you didn't read through all my posts correctly.

I was looking to fit an alloy inlet manifold to my 120 engine but due to the size difference the fact that the ports don't match and there would be a step this would be detrimental to the engine peak torque.

I wasn't looking to fit the cams for my 135

You can achieve hell of a lot more power than 160 PS without VVC. if anything the VVC system is limited in terms of tuning

[ashcapri28]

Typo in last message, I wasn't looking to fit 135 cams in my 120 head

[Rob Bell]

I have the R140 cams (the ones used on the Lotus 135 sport and the TF135) on a standard head with standard valve springs. No problem - and I don't hold the horses on Project Shed, as you can imagine.

There has been a lot of debate regarding the valve springs on the TF135 and whether they're the same as on the 120PS variant. But since Piper don't recommend changing the springs for their BP270H cams (similar lift etc), I don't think it is too much of a problem. Engineers will likely disagree

Glad you decided against the alloy inlet - I get 140bhp from both of my MGFs running 135 cams and on plastic inlet manifolds. As you say, the VVC alloy inlet manifold is matched to the larger ports of the VVC head (I say matched - that's probably being a bit kind to Rover's casting accuracy...), but the ports on the MPi head are smaller, and there is a step, and this will affect the flow into the head. Also, the mating flange to the manifold is marginal, leading some to build up the flange on the head before porting the cylinder head to match the inlet manifold. The gains for all this hard work are not substantial - but if you are racing in a particular class that permits these modifications, then "every little helps"!

[talkingcars]

I was a bit worried when I read about the 135 springs being different as I didn't save them when I scrapped a 135 engine, I did keep the cams which are for sale.

I also have a 135 gearbox which may be available with a MGF bell crank.

[RobboMC]

So Rob you're saying I should be able to bolt Piper BP270H or 135 cams and a 135 throttle body into my 120PS and the valve springs will last OK??

Hmmmm food for thought at the next timing belt change.

[Mykel]

According to the parts list, just two different kinds of valve springs were used on the MGF/TF:

LGL10008 - for all MPi engines, 1.6 and 1.8 alike, no difference between 120 and 135 bhp
LGL100460 - for all VVC engines (145 and 160 bhp)

[ashcapri28]

So I have bought a brand new plastic inlet manifold.

I've done this as I like to do the job once in case my old manifold is warped around the gasket which is why I'm getting my problems.

So now do I replace my black injectors with the higher flow rate blue ones.

I found this information

This is for the blue injectors as found on the 135

1 injector for engines upto around 38 BHP
2 injector for engines upto around 76 BHP
3 injector for engines upto around 114 BHP
4 injector for engines upto around 152 BHP

The price shown is per injector - adjust your basket quantities to suit your application

SPECIFICATION (Using N-Heptane)
- 208 cc/min @ 3bar (43.5psi)
- 20 LB @ 3bar (43.5 psi)
- 14.5 ohms resistance (HIGH impedance)
- EV6 Long body style
- Standard 2 pin Junior timer connector ( often called EV1 connector

Now for a standard black mpi fuel injectors as fitted to my car.


So this gives the following options
1 injector for engines upto around 34 BHP
2 injector for engines upto around 68 BHP
3 injector for engines upto around 102 BHP
4 injector for engines upto around 136 BHP

The price shown is per injector - adjust your basket quantities to suit your application

SPECIFICATION (Using N-Heptane)
- 190 cc/min @ 3bar (43.5psi)
- 18.1 LB @ 3bar (43.5 psi)
- 14.5 ohms resistance (HIGH impedance)
- EV6 Long body style
- Standard 2 pin Junior timer connector ( often called EV1 connector

I would imagine that the specification given above for 136 bhp would be at 100% flow rate therefore the maximum in my opinion it's never good running anything at maximum capacity.

I'm not sure how much power my car is making.
I can say that I have a performance exhaust stainless steel

brand new catalytic converter
the standard exhaust manifold I will be replacing with one from eBay made of stainless steel 6 Bolt version.

Air filter cone mounted in side vent alloy pipe from a cone filter up to throttle body.

All sensors, fuel pressure regulator, coil packs and leads everything that could be changed 4 brand new items have been changed to ensure perfect running.

Compression test done and I'm quite high on the compression 245 PSI across the four cylinders

I'm theorising I've got about 130bhp

GPS tracker 0 to 62 8.6 seconds how accurate I don't know but I can keep up just with a Fiat 500 Abarth off roundabout down the A1 no traffic he starts pulling away once I get to about 80 90 mph. But still on his tail chasing well over sensible speeds. Again I must stress that there was no one else on the road. And do not usually drive in such a manner.

[Rob Bell]

So Rob you're saying I should be able to bolt Piper BP270H or 135 cams and a 135 throttle body into my 120PS and the valve springs will last OK??

Hmmmm food for thought at the next timing belt change.

Yup - 10k on the Shed without trouble On N7 I used the whole TF135 head, complete - but as Mykel says, there are only two valve spring part numbers listed...

[Rob Bell]

So I have bought a brand new plastic inlet manifold.

I've done this as I like to do the job once in case my old manifold is warped around the gasket which is why I'm getting my problems.

So now do I replace my black injectors with the higher flow rate blue ones.

The standard fuel trim on the K-series is generally rather rich so I doubt, with the relatively minor modifications on your engine, that you'll need to run higher-flow injectors. But the way to tell is to go to a rolling road. On mine, I found that my car made 5 bhp MORE with LESS fuel. Previously, when I fitted a higher-rated fuel pressure regulator, the car ran richer and the engine made less power.

If you get the head fully ported, fitted even hotter cams, then you may be pushing the envelope of the injectors. The counter argument is the the higher-flow injectors will give you more scope for future development.

So yes, you can fit higher flow injectors, but get the ECU rolling road re-mapped to optimise your set up - which is obviously the best approach to this problem. Mark Stacey @ KMaps and Stephen @ SAWS tuning can do this for you