998 Turbo Build - Slow Progress
Turbo Mini Forums

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

So is there a noticeable difference between the MG Cam and the 274?

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I don't believe that anyone has actually done and back to back tests, but the science suggests that the higher LSA is better with a turbo A-Series.

My simulation outputs:


Depends what value you put on a nats cock.

Edited by Paul S on 13th Feb, 2014.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Interesting that the theory suggests that there isn't much difference. Is that simulation for a 998? some big numbers there.

I was planning a rev limit of 6500-7000, so according to the graph the 274 would give 2-3hp more all the way up the rev range.

I think i'll stick to the MG cam, for costs sake, can always change when I get bored of having the car in one piece..

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It's a highly developed 998 sitting on my workbench. Running 0.8 bar boost in the simulation.

If you already have the MG cam, stick with it.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Thanks Paul, MG cam it is then.

I started the RTS build today, got as far as taking the spring plates off. I remember reading that the hole that should be tapped M8 is slightly undersize, so requires a high quality tap. Can anyone recommend where to get one from?



Otherwise just been putting things through the blasters and alodine tanks.




Picked up a Minispares 4-Pin diff from Jonny as well, thanks for that!



Hopefully some major progress soon with payday, Just a short list of things to get through..

get the welding done on the car and spray the engine bay and font, Get the gearbox back from GuessWorks, Block back from machinists, then get the crank and rods crack tested at work, then send the crank, rods, pistons, RTS and pulley off for balancing. Then I can build the bloody thing..

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Progress is slow and money is thin, and the work seems to be mounting up rather than diminishing. Sent some testers off to the platers to have a look at the colours and finishes they do.

Also got the paint shop at work to hang some of my stuff up next to some parts and get some overspray on them.



Got a couple of good pics of the head as well, can see the work that has been done now.



Parts for the RTS clutch are all stripped, just need to make the spacers and tap the back plate and assemble.


Decided to make buttons up for the pistons, using a PTFE rod. Aiming to have the revs limited due to the cam and not any other factor.


The car isn't looking good, going to get the major welding sorted and take it to a bodyshop once I can move it. Also masked up the engine bay for the welding and will be painting it BRG to match the car.



Also some comments were made about the quality of the finishing of the pistons. there are a lot of flashings and sharp edges, and some deep stamps on the crown. It was suggested to smooth out the casting marks and sharp edges around the gudgeon pin lube hole. any thoughts?


Also, this is why I get laughed at when I bring things into work.

Edited by Mike-998 on 12th Mar, 2014.

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I had the piston buttons drilled to save a 10th gram and let them breath also are you going to dome them or leave square?

now you mention the pistons far as the de stressing is concerned u got me a bit worried as it apare the are the same ones ive got but in 60
wonder if there have been many cracks venture from these bits?

that looks to be a big piston 7-8" ? whats it from

i like that pleating you done too.. i can image how it would look on a previously polished casting nice and smooth almost like a cnc part from solid!

I wasn't planning on drilling them no, do you think it would help? They will all be rounded off yes, you can see the one I've done on the bottom left, the others are fresh off the lathe.

I've never heard of any cracks from them, it was just a comment made by one of the directors at work that the finishing of the casting was poor and could lead to failure. I think I'll just take the major flashings out and deburr the holes.

The piston is from a Russian radial engine, can't remember the displacement but there's seven of them.

Thanks, The alodine doesn't change the surface finish of the metal, so as I've just blasted the casings it has come out dull. Polished and freshly machined things will come out shiney though

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ive found it helps in getting them out of the pin via a bent spike to get behind them n push pull them out

just had a thought tho... wonder if the pin will/could fill up with oil and add weight? potentially un equal weight.. hmm

That's a good idea, struggled to pop them out a few times because they've suctioned themselves in. Is it just a small hole down the centre?

I'm not sure on that, the only way oil can get in the pin is up the side of the skirt, if have thought it wouldn't get in with the buttons there, but maybe if there's a hole in them..

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think its about a 3mm ?

ive re though my comment lol your right its unlikely there will be much oil work its way up the piston to bore clearance then make a turn into the pin via the hole
i think the oil getting in that clearance gap should be taken care of by the oil ring and pushed threw the drilled holes in the piston rather than filling up the wrist pin

i was thinking for a second i had slipper skirt pistons where its only a part skirt piston haha

They look good, I don't know what other people have done but I cant see it doing any harm, so long as it's all deburred.

Where did you get your material from? Just had a thought today that I don't know the specs and it doesn't feel like It'll stand up to the heat? Just bought some generic PTFE rod off ebay..

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not sure exactly on the material but its what the shop supplied apparently they do them free for the big dolla builds as it is farly quick to spit them out once set up

Had the block and head crack tested, block is fine, so can start the build up on the soon - cam bearings in, paint etc.

Bad news on the head though, just the one crack on the thermostat flange, looks like it goes right down to the waterway to the bypass hose. Managed to get in touch with some welders through work and are going to give it to them and see if it can be fixed.



In other news, front subrame is pretty much ready to be built up, just waiting for parts from minispares. Still need the welding done on the inner wing.

Finished the piston buttons:


And got the blanks for the RTS spacers made up, just need to drill and mill them to 8.9mm.

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Bad news on the head Mike. Hope it can be sorted

BHP sells engines, but Torque wins races!

Thanks, would be gutted if it scraps the head after Benross has done all the work on it.

I need to do a small patch repair to the driver's side inner wing. The lock up the car is being stored at has no power, and all of the mobile welders have been reluctant to help, due to not being free during the day.

My question is can I weld in a patch with an Oxy-Acetylene welding torch and some welding wire? As this would require the hire of only one bit of kit, rather than paying to hire a generator and a welder. Doesn't need to be a masterpiece just has to pass an MOT.

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Latest hiccup is that the OD of the RTS spacers is too big, it fouls on the pivot ring. They're too small to put on a lathe and machine down, what would be the best way of doing it?

Spacers surface ground to 8.90mm



Also got all the running gear and the block painted up





And samples back from the electroplaters:


Subframe powdercoated:


And rocker cover polished and alodined


Just need to get the rest of the stuff off for plating and I can finish the assembly of the subframe and get it back on it's wheels.

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for a crack like that on the head, I would look at brazing it,

For your spacers just stick them on a bolt and hold that in the lathe.

While I'm on the subject do you have to make the spacers the same length as the originals when you do an RTS? What have you made them from? Does it need to be hard like the originals?

I'll ask the welders about brazing Joe, thanks.

Didn't think about putting them on a bolt, that should work.

I made them the length of the original ones plus the depth of the extra spring. I just made them from some steel rod that was lying around at work, couldn't say exactly what it was sorry.

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Sounds good as that's what i did on mine! Untested so far tho!

Brazing works. I had a head with was ported to big and in and outlet broke trough the oil way. My mate brazed it and no problems so far ( one year now on a 1293 with 13,7 compression ratio)

you can do anything if you set your mind to it...
i rather blow it up winning than keep it together losing.

finish date set for project 1... march 2018

Thanks - May not be the end of the head then.

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