Mild performance mods

[winger300]

A little searching on ebay i found this...http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... gory=43122

Will this fit a standard 1098 without having to replace the exhaust. And will it give any noticable performance boost?

[Cam]

Well! The picture seems to be of a seat so that's a good start!

On it's own that item will be no good for a standard 1098. The carb is too big, has the wrong needle and you will need a complete new larger bore exhaust system to fit the Minor, as a Metro one won't fit.

A better bet would be a 1 1/2" carb (HS4 or HIF38 with AAM needle), an alloy inlet manifold, a stainless steel exhaust system and an LCB exhaust manifold. But that will only give you about 15-20% performance improvement when properly set up.

The eBay item is really only worth getting if you have a 1275.

[winger300]

Yeah, that picture of a seat did seem odd. Thanks for the advice. I think my best route then would be to keep an eye out for a cheap 1275 head

[rayofleamington]

Careful Andrew...
You'll re-open the big debate on 12G940 heads and the requirement or not for pocketed blocks! ;-)
but yes, a big valve head with the 1.5" carb and a bigger exhaust will make a significant improvement to a 1098.

[turbominor]

or go my route and fit a metro turbo setup on to the 1098, appart from making the exhaust it is easy to fit

[Cam]

or my route and fit a tuned bored out 1275!

We all have different approaches all with their own benifts and shortcomings.............. I can't say which is best as it depends on what you want out of it in the end. If you want a small power increase then tune the 1098. If you want more power then you need to increase the ccs as well as tuning it. The easiest way is to fit a 1275 or if you are not bothered about keeping an A-series engine then go for the Fiat twin-cam.

If you are going down the tuning route though, whatever you do you will have to fit a decent exhaust system as the standard one struggles to keep up with the standard 1098!!

Also, don't forget that whatever mods you do to increase the power - make sure the rest of the car can cope with it (brakes, suspension, etc.).

[winger300]

Yes, i think a turbo is a little excessive for what im after.

I'd like a little more acceleration, but without having to improve braking/suspension etc.

Perhaps a 1.5" SU, K&N and a bigger exhaust is all i need.

[turbominor]

to be safe what ever you do you must at least fit a set of marina or sierra disks as your insurance company are un-likly to cover you with engine mods.

[winger300]

What is the minimum boost you can get out of the MG metro turbo? Is it possible to set the boost low enough as to not need low compression pistons?

[turbominor]

as standard the mg metro turbo used a modulated boost system, the actuator is set to 4psi (as per my car) so 8.3:1 standard 1098 is fine. But the metro has a small ecu and air blead valve that lets a bit of air in the the pipe controling the actuator, this lift the boost to around 7psi!

this was done to lower the midrange torque to protect the gearbox.

if i get by 1300 i will be selling my turbo setup and 1098 overhauled bottom end

[winger300]

What kind of performance improvement would i see with 4psi boost over a standard 1098?

[turbominor]

65-70bhp by my calculations, i recon you could run 7psi on a good engine

[winger300]

65-70bhp sounds pretty reasonable, and i wouldn't need to change the reardiff/gearbox correct?

Have you replaced you rear axle & gearbox turbominor?

[Cam]

The rear axle should be able to just about cope with 70BHP. The gearbox too for a short time. The gearbox is the weak link though.

[rayofleamington]

Hi Nick
The 948 is a wonderful smooth and sweet engine!
I left mine completely standard and enjoyed travelling at the speed limit, even if it takes a while to get there.... do you really need more power? It might make the car closer to competing trafffic but the trade off will be part of the character.

The 948 gearbox isn't renowned for strength - so that ought to be done at the same time.
Are you running 7" front brakes? They will have to be upgraded also.

but if you are going to do it with the brakes and gearbox, it's cheaper simpler and easier to pick up a 1098 engine (and the matching brakes and gearbox, carbs and manifold), rather than mess about with a 948. This gives a noticeable boost over the 948, and if you drive the 1098 hard it holds it's own with most other road users.
This way it's just updating the car to late Minor spec. If you add a 12G295 head at the same time it'll make a nice well rounded package.
The engine, carbs, box and brakes can be got for £50 to £100 if you look long and hard enough.

Going slightly beyond your 'mild tuning'...
If just the head isn't enough and you want to go more than that then consider the more boy racer options like the big carbs, big exhaust, and/or a 1275 engine. Going this route it's probably best to go for a Ford box. You'll need to have disk brakes as well.
Added to that you may want tele-shocks and uprated torsion bars..

[Peetee]

I modified a 948 very cheaply and easily with a 12G295 head, water heated inlet manifold and HIF38 carb. The standard exhaust manifold was retained (after cutting off the inlet section) but the rest of the system was a standard stainless item. the car had already got a 1098 box - as many 948 cars do now.
The performance proved to be well in excess of what I expected. I also have a 1098 car and the modded 948 definitely felt quicker. It's always hard to compare a revvy car with one with power in torque - like the 1098. I recorded a 0-60 (from the speedo) of 18 seconds. This is certainly a massive improvement over the standard cars 30 seconds but bearing in mind the speedo could be inaccurate the true reading could be 4 or 5 seconds out. It really was a hoot to drive and would accelerate smothly from very low revs and easily hold 70mph uphill with pedal movement to spare. I would recommend this route as a start - providing your engine (and brakes) are in top condition anyway- It's very easy to rev the thing high as it just keeps going!!

[Cam]

Don't do it Nick!!!! (well, not until I have had a drive of your 948 first!).

I thought of asking you yesterday when you came up but I thought you might have thought the request a bit strange Plus I had MG to be getting on with!