My first car with a tuned/modifed engine

[Brithunter]

Hi All,

     It was only the other day when it actually occured to me that this MGF 75th Anniversary edition is the first car that I have owned that has been slightly tuned we do not know as yet how much difference the modifications have actually made but a session on the rolling road/Dyno will happen once funds and time allow. Firstly the induction set up needs finishing off and fitting as right now she is running an open cone K&N 57i induction set up which is not really much cope as it sucks in all the hot air for the engine bay.

    Factory specs for the MGF MPi is 118 BHP but we have changed the inlet manifold, plenum, throttle body for the alloy ones off the TF 135. It's claimed that this reduces the torque but it's not noticable when driving normally if indeed it has done so. The TF135 gave a factory claimed 135 BHP but being much later it also runs a different ecu unit running Mems 3 whilst the early MGF's, like mine, run Mems 1.9. The Mems 3 is remappable the mems 1.9 unit is NOT.

    The TF135 also ran higher lift cams and I acquired a set that had been adapted to ditributor drive to suit my engine the TF runs wasted spark system and does not have a distributor. The R140 (TF135) cams have about 1mm more lift and a longer duration but of course they only really come into play at higher revs.

    Coupled with the fettled, removed the restrictive internal welds, TF 6 stud manifold and down pipe and a less restrictive CAT and S/S sports silencer she certainly is more responsive and willing to rev. The later 6 stud manifold it seems has better primaries than the earlier 4 stud manifold so it will be interesting to see how she really is perfoming in the power stakes... if we can get the money together the idea is to next have a head flowed and ported with larger valves to make the most of what we have. However this is not cheap so may take some time to get the funds together.

Once the head is done we could be looking at around 160-170bhp which is a decent increase percentage wise in engine power. It will also be interesting to see how the torque is doing from standard!

[farmboy]

If you port the head you might consider milling it to increase the compression ratio. Also can you buy or build steel tube headers for it? On American v8 s just doing a three angle valve job and blessing just behind the machining gets you a basic port job that builds more power across the whole rpm range. Ports can be opened up to where they make way more power at the very top end and fall on there face for the biggest part of the range. Have fun with the hotrodding project!

[farmboy]

Another thing I just thought about if you have not done it already is to make sure the ports in the head match both the gaskets and the intake manifold and the exhaust manifold. A little free horsepower can be found there at times.

[farmboy]

With you cam change did you check valve to piston clearance or are both engines pistons identical?

[gitano]

Is any of the above "english". Looks like "greek" to me.
:D

Paul

[farmboy]

You would love hotroding Paul. Lots of fine machine work. And precision building.

[Brithunter]

Thank you for the suggestions and to answer some of your points and questions:-

No problem with valve clearence as these cams come from a slightly later model, same engine, same block, head and pistons just slightly higher tune. Factory specs for the MGF Mpi version is 118 BHP the later version/model the TF went to wasted spark ignition with two plug top coil packs so no distributer and a different ECU set up (known as mems 3) and gave a factory claimed 135 BHP. The early Mpi's like mine a version  called mems 1.9 which is not mappable unlike the mems 3 version.

   This is my first MPi with the head off for gasket replacement:-



You can see the factory exhaust manifold to the left, to the right are the steel coolant tubes which are now bright yellow after being cleaned and rust treated, and you can see how little room there is in the engine bay



Note the hand scraped chamfers to the ports...... This is the remove the sharp step between the small port in the head and the larger one in the alloy lower intake manifold so yes there is a mismatch.





On the VVC engine (Varible Valve Contol) the valves and ports are larger and the alloy manifold was originally designed for that engine. Just another reason for having the head ported and flowed. Doing some research is seems that if we leave the valves at their standard slightly small size for a 1.8 litre yet have the chambers uniformed and matched for volume. Ports flowed and the 3 angle valve seat it will give more BHP but also retain more torque lower in the rev range. With larger valves then the power (BHP) is greater but it can be down on torque so engine becomes "cammy" and needs to be revved more in normal driving. For a road car this is not so desirable.

    The compression ratio is quite high as standard so once again to avoid detonation on pump fuel it will remain standard.

 This is the head:-



DOHC 16 valve 1.8 Litre. The valves are a mite small for great power outputs as the engine was originally designed as a 1.4 and 1.6 litre. For power outputs of over 160 BHP they need to be larger really. The same engine was fitted to the early Lotus Elise until MG/Rovers demise.

 Remember this is a mid engined car. There are a couple of full branch, Tube manifolds, available from a couple of performance specialists but heck they are expensive. In fact they cost twice what I paid for the car at around $800 USD. This is what the complete exhaust looks like:-



The S/S box is a performance one this one is about a year old and was on someones track car. new they are beyond my meagre pockets reach as they cost around $700 USD.

    I hope I have answered the points you raised.

[farmboy]

Interesting the stock exhaust looks like four into two then two into one. Very simlsr to a Doug thorley tri y header set up. Generally that arrangement makes more bottom end. Far better looking stock exhaust system than most cars I have seen. By the way nice looking car.

[Brithunter]

Your right of course about the exhaust manifold (header) and down pipe. The later model one pictured has slightly longer primaries than the earlier 4 stud exhaust. I only fitted the CAT and rear box from that set up onto the Anniversary the 6 stud manifold and a new down pipe is now on the VVC model. The downpipe in the phot has been welded badly at the flexi pipe so i bought a new one to be on the safe side.

There was a V6 engined prototype in development using the 2.5 Litre KV6 engine but ti was never finished. There was aslo a Super charged prototype that suffered the same fate. A company here in the UK did do a limitem edition super charged model called the Panther which also had a body kit and a kitted version without the charger called the Cheteah. There are a couple of companys that also do Turbo conversions I had a test run in one in the summer.......................... cannot say i was that impressed though.

Thank you for the compliments on the car. The only reason it never made it to the US it seems is fear of court action over the way in which Rover's former owners ditched the US operation. By 1995 when the MGF was developed the company was owned by a different parent company ................................... BMW. Also perhaps BMW didn not want competition to their own Z3 Roadster?

[farmboy]

Can you buy nitris oxide there? As long as you add the proper amount of fuel so an engine does not mean out you can have a lot of fun. The kits are the cheapest horsepower you can add but you pay down the line getting the bottle filled.

[Brithunter]

Yes you can.  Now and in fact there is an oufit that does the kits about 18 miles from here. I spoke to them as theyre were supposed to be piggy back ECU tunning supplier and centre for setting them up. Superchips was the brand name of the piggy back gizmo however they no longer do these it seems. The gizmo gave a claimed 8-10 bhp..... on the NASP engines much better on turbos it seems.

[farmboy]

The superchips reprogramer can only change timing etc on a naturally aspired engine with the turbo they can increase the boost pressure and fuel. The suoerchips are used extensively in diesel powered pickup truck around here. Then and others.

[Brithunter]

Would you believe it the new exaust front pipe has failed at the joint tot eh flexi bit. So have had to buy a new one so the old one can be removed and sent back for awarrenty claim. It's only been on a few months and only bought it in the middle of August.

Blowing like a good un and sounds a bit like a tank.