Small bore. Target 200hp
Turbo Mini Forums

Hello peeps,

So i thought it was about time that that i finally started to put together a proper build thread. Having previously posted a bit in the 998 specific forum, and received some great guidance advice it is a little overdue.

So prepare yourself for a little bit of history to bring you up to date with the car and where it is at the moment.

I purchased the car back in 2011 as a standard 998 Mayfair, came with solid body work and a very rough engine. At the time i was at college and rebuilding the engine made an excellent final project. In the initial rebuild the car gained a +60 overbore, Hiff44, 286 cam, mainflow manifold and system, heavily worked A+ head, 3.44 final drive and a few other bits and pieces. If i remember correctly it made about 62 or 63 hp. However the pre-verto destroyed the thrusts and it developed a passion for drinking oil. So out it came, taken out to plus 80 thou. However once again it developed an oil consumption issue. So out it came, turns out that the machine shop had given me 20 thou piston to bore instead of the 2 thou. So that was a little bit annoying. So once again the engine was rebuilt, this time +100 thou the head was also skimmed to bring the compression ratio up to around 11:1. This not only helped increase the power, but also to help reduce the fuel pooling and other associated big overlap issues.



After this final build did she move, and she was so much smoother at idle and in the lower revs. However this wan not to last as after 2 days, while driving home from Bisley, she developed a rattle, that got worse and worse as i drove home. Once home, we retarded the ignition but the rattle continued. So the decision was made to pull the engine. I got 2 days out of it, my misses and old man were not best pleased. As the engine was stripped down the source of the rattle became clear. Con rod number 4's bearing had for what ever reason decided to disintegrate, destroying all of the other bearings as well as the surface of the crankshaft. The bearing itself had got hot enough to have blued in the oil. The only thing that saved the engine from totally blowing were the ARP rod bolts.

So as i stood there staring at the mess of my engine, i decided that i had had enough of putting hours into essentially the same engine over and over again. I had always wanted to make the step to fuel injection and thought well if i am doing that, then i might as well turbo the car aswell. So i started to do my reading up, which led me here to the forum.

So the initial idea was to reuse as much of the old NA engine as possible, dishing the +100 pistons and modifying the chambers to bring the CR down to around the 9:1 mark. However, it soon became apparent that this would not be the best route. So i decided to sell off the old NA engine and start again. So began the search for a suitable start point, after a few false starts i managed to find a good block. my intention was to fit the block with forged Omega +60 pistons. Modify a 12G202 to take some 1275 valves. After looking around the forum i had taken the decision to polish the inside to the block to encourage oil drain back. i also decided to polish up the con rods. After a few practice goes, it started to wear thin. At this point i sold my +100 block to a dude, who while chatting to my misses mentioned that a man called Rob Selby, at Selby Engineering, produced forged 998 rods at a reasonable price. Along side loads of other really cool and well engineered parts . So after a couple of phone calls i took my engine parts up to Rob to have him complete the machining work on the block, alongside supplying some of his forged rods and his super finished crank. At the time he was building a couple of mini 7 engine for the new season. And as i was going back to uni i didnt mind the wait. After completing my final block of uni work, i thought i should chase up my engine. it was at this point that i found out that vary sadly Rob had passed away, after a long battle with cancer. Robs passing is such a huge loss to not only to the mini world but the engineering world as a whole.

When i had dropped of my parts with Rob, we had spent a lot of time chatting about engines, parts and he mentioned that he had had designed a series of 6 sets of forged cranks and rods. Originally they were for mini 7 racing, but due to politics and the like, they had been banned. With Robs passing i began talking to Lewis, his son. I mentioned that Rob had spoken to me about these cranks, and through Lewis i was put in contact with the owner of one of these sets. Having been used in only 6 races, they are in excellent condition (i will get photos up in the next couple of days).

So this is where it gets really interesting, with forged pistons, rods and crank. I now have a super solid bottom end, and the potential to push for reliable, big power. The only issue being that the Omegas are fitted with a 16 mm gudgeon pin and the rods were fitted with 18 mm pins. As they were designed to be fitted with a set of pistons to Robs own design, that should give me almost exactly 1 liter. So the omegas are up for sale, check the for sale section.

So with this pretty insane opportunity to push the power that i can achieve forward, and changes the goal from just doing the conversion to making big power with the conversion.

So yeah, kind of brings the build up to speed. I will get a spec list up in the near future, along with a few pictures, including the beautiful crank.

#Tried It 2

Edited by #Tried It 2 on 21st Oct, 2017.

Heya.

So here are the pics of this gorgeous crank and rods.







I still cant believe how lucky i was to have the opportunity to own this set.

The turbo that i have chosen for the build is a VL38 off of a fiat 500 Abarth. I chose this turbo as it from a modern vehicle but still uses a vacuum operated actuator. I search around on eBay and purchased a turbo from a low mileage write off that was being broken.

The turbo as it arrived:






Though it looked in good condition, i decided to send it off for a rebuild with TURBO DYNAMICS. While with TD they suggested that it would be possible to modify the turbo, by fitting a larger billet compressor wheel. According to TD on the Fiats they have made over 200bhp, so i couldn't resist.






Ime keeping it all wrapped up until i need it, to keep the dirt out.

I spent a long time deciding on a throttle body. As i was after a largish butterfly fitted to a car which was preferably turbo as stock and with either a built in stepper motor, or only a single take of for idle motor. After a long search i came across the 48mm body fitted to the 1.8 Turbo K Series. They are produced new by Webcon which was positive.





I was also lucky to get hold of a NOS Rover full bypass thermostat. XL Motor-spares in New Malden, just up from Krispy Kreme's. He has a whole stock of NOS part for 80's and 90's cars. Graham has a wealth of knowledge and is always willing to help out as much as he can. So well worth a look if you need an odd part.


I also thought i would include a couple of pics of the inside of the block. Little bit filthy atm, but you can see the polishing. Lots of hours work haha .




So the Spec as it stands is:

998 A+ internally polished block. Fitted with Forged 998 pistons, Forged rods, Forged Crank all designed by the late Rob Selby.
RTS clutch spring, rally spec plate and MED Lightened Verto Flywheel.
This will all by dynamically balanced.

Modified 12G202, the head will be extensively modified. The intention is to re-space the valve guides to enable the fitting of larger 1275 valves. While staying in a small bore casting.
The intention is to complete an 11 stud conversion, to make sure that all of the boost can be contained.
The head gasket is to be a MLS design.

The exhaust manifold will be an equal length side mounting variety, and the inlet will be via a plenum chamber. The idle control valve is a standalone Webcon item.

Cooling will be via a Davis Craig 80L pump, and utilise a full bypass thermostat. A 2 core super cool and an electric fan.

Fueling will be controlled via an MSX3 ECU. I am hoping to run closed loop. Sequential injection and Sequential Spark. Using the long injection duration to give the best possible fueling.

The inter-cooler will be a custom made item. I am hoping to essentially fill behind the grill as much as possible with inter cooler and duct air to the side mount radiator. I am also fitting a 60 AMP Nippondenso alternator fitted as low in the sub frame as possible, to give as much space as possible.

I am intending to fit a boost re-circulation valve.

Crankcase ventilation via a catch can piped back to before the turbo.


As for the rest of the car:

I am re-routing the brakes to behind the fire wall, to reduce the exposure to heat. so essentially a brake pipe tuck.

I am also conducting a bay wiring tuck. Basically to keep the engine bay as clutter free as possible.

There are a few bits that i no doubt have missed off but its a pretty comprehensive list haha.

I am always open to any comment or advice

#Tried It 2

thats some nice looking kit,

TBH i would be looking to go away from the 5 port to make the most of the bottom end, SC 7 port or 8v fiat head?

Will and ben on here did 180hp on a 998 with a SC 7 port, i guess thats your target to beat.

the 8v fiat head can be made to flow and rev well, would be a good option IMO

A well ported 5-port head will make the most of that bottom end if you use the right manifold design, cam and turbo.

It's good to have someone else pushing the boundaries of the 998 5-port. Definately some uncharted territory and potential.

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."

Thank you Joe, it will be interesting to see what difference the bottom end will make. During the testing on the CNC software, the crank was being revved to 10,500rpm before they encountered any issues. The previous owner had taken it to 8500 again with no issues, so it should be pretty solid.

I get where you are coming from with making a conversion to 16V, but first i would like to see what a 5 port, small bore is capable of.

Is there a feed on the forum for will and ben's build? Was it a standard bore or an over bore?
Do you know of anyone who has made high power figures with a 5 port small bore?

Hey Paul, the cam i have is the Avonbar phase 2, which i know not everyone is a fan of. The turbo is a modified IHI VL38, so it will be interesting to see when it spools. As for manifold design, apart from being equal length runners, do you have advice?

As for cylinder head ports, i believed that the 12G202 would benefit mostly from a clean up of the ports and a bit of opening around the valve guides. Obviously as i am intending to change the position of the valve guides, the porting may be a more complex.

Glad to see that you are seeing my ambition in keeping it all small bore. I was expecting to be told to stick a 12G940 on it. But i am determined to see what the 998 is capable of. Even though is is definitely the more expensive and complex route to take. It will make it different to what others have done

#Tried It 2

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."

I don't have much in the way of technical knowledge that'll help here, but you have come to the right place!

I really like the sound of this, if you asked me what my money-no-object mini would look like it'd pretty much be this!

It'll be great to have this documented on the site too, I'll definitely be following the build.

http://www.turbominis.co.uk/forums/index.p...tid=469104&fr=0

Oh interesting, a revvy cam with a nice idle It will make a change from the bigger duration NA camshafts with there horrendous idle.
I was intending to use the 1.3 roller rockers that i had fitted to the engine previously. Cool Thank you for the tip, on the valves.

Nor have I to be honest, it seems that it is not commonly used in the aftermarket. So again it will be interesting to see how it works. for the exhaust, i was thinking 2 inch down pipe, into a 2 inch system.

With the tuning of runners, if i remember correctly, the pulse can only be matched to a certain point in the rev range. The shorter the runner, the higher in the revs the benefit is felt. The longer the runner the lower down the rev range the benefit is felt. Hence, some engine being fitted with ECU controlled variable length inlet runners. So how do you pick the correct length?
However it is awesome to know that the benefit can be that great. It is something that I could have easily overlooked.
As for the shape of the inlet runners. As 300mm seems like it could be a squeeze with straight runners, with the standard firewall. A curved runner is almost definitively going to be needed. I presume this will slightly reduce the peak power. Though thinking about it, i know some of the Honda manifolds have curved inlet runners.

I presume that's pipe size dimensions, with all runners equal length? Or do you mean having the two outer ports on shorter runners that join together before then joining on to the center port runner a few inches before the turbo exhaust inlet.

Thats like a hint hint moment, get it done properly haha. Dose Turbo Phil still do work?


Hello Mike. I get that feeling, the wealth of knowledge and experience, trial and error that is available is an awesome resource.
Thanks, sadly its not a cheque book build. Hence trying to flog the pistons. But after previous builds where i have opted to take a cheaper route, and come unstuck, i want to build it right this time. and avoid the previous pit falls. And of course make silly power on the way.
Yeah, so people can read over my inevitable mistakes, and hopefully avoid them

Also managed to get some work done. By that i mean lots of attempts and then a complete change of direction.
So one of the the things that i would like to do while rebuilding the car is to 'tuck' the wiring and brakes. Stealing a bit from the VAG scene, this has both a visual and physical benefit. Visually, i like the look of a tucked bay. Cleaner, less cluttered, with only the wiring that is necessary on show. And physically, that hot turbo is precariously close to the brake bias valve. So to avoid heating up the brake fluid unnecessarily, i am planning a heat shield but also to move the brake bias valve to inside the cabin. To behind the fire wall. Obviously this means rerouting all of the brake pipes.

So i started with some copper brake pipe and borrowed a flaring tool.
First routing idea:


Stuck out quite a bit. So changed it a little.


But after 5 hours of bending and fiddling, and getting some quite nice blisters developing, i came to the conclusion that: firstly the pipe, once bent up, was a pain to fit. And secondly, it work hardens horrendously so is not super suitable to run internally under the carpet. So went to Think Automotive and had theses made up.

Solved the issue, and they look sweet, plus the fittings rotate. Like those on copper pipe, much easier to fit than the Goodridge ones i have. So i think i will be running the rest of the car with these :)

#Tried It 2

Looks a good project, interesting to see how you do the shaved bay etc.

And Phil does still do work, just drop him a PM or you can find him on facebook.

Edited by Paul S on 30th Jun, 2017.

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."

For exhaust it maybe worth while speaking to matt on here who runs fusion fabrications, he has built some epic side, top and log manifolds for the a-series

Drives
-Ford S-max Mk2 Ecoboost
-Rover 100 VVC #2 - track project

Searching is all you need on TurboMinis

I find this stuff on 998,s fascinating even if a Helmoltz equation makes my brain hurt.

I have daydreamed about a turbo screamer 998 in the A35 - but goodness knows why !

So, good news after waiting 4, nearly 5 months. The pistons to fit the rods have finally arrived. So the engine build can finally begin.
I have also picked up a set of superior main bearing studs, some lightweight cam followers and some BMW under piston squirters to hopefully keep the piston crowns from melting :-S
I will get some pictures up in the near future.

#Tried It 2

200 bhp in a small bore 🤣🤣🤣

I have started posting on Instagram also my name on there is turbomk1golf

Nothing is impossible it just costs more and takes longer.

i thoink paractically to make 200hp you'll need to be hitting 9k, with an efficiant head at about 22 psi boost, or about 7500 at about 30 psi.

In theory it is possible, either revs or boost. What we don't know are the small bore inherent weeknesses that will stop us getting there.

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."

THE 998S ARE COMING FOR YOU SIMON!

They don't die, they just get faster!

Yes i moved to the darkside

Instagram @jdm_brett

OMG 😲

On 29th Oct, 2017 Brett said:

On 28th Oct, 2017 Shauna said:
THE 998S ARE CUMING FOR YOU SIMON!

On 23rd Oct, 2017 madmk1 said:
200 bhp in a small bore 🤣🤣🤣

Shauna !!


im watching with interest, my mini when 998 was the most fun i have ever had in a mini

I have started posting on Instagram also my name on there is turbomk1golf

Nothing is impossible it just costs more and takes longer.

So as i promised a couple of pictures of the pistons.







The main benefit being that these actually fit the rods, which is nice. They come dished, but have also had some of the crown removed from underneath in the factory. I presume that this is to make them as light as possible to facilitate the 8000+ red line. However, this does lead to a crown that feels slightly thinner than the crown of the +60 omegas that i have. So hence the need for the under crown jets, just to be on the safe side.

Its nice to see Simon offering all the support possible, his belief in the project and its 200hp target is tangible
However i do have to say a big thank you to him for sorting out a couple of the more complex pieces of the project so far.
The RTS which started out as building just the spring but has now grown into Simon putting the whole assembly together.(pics to come). And the building the cam sensor out of an old dizzy. Which is pretty cool.

As i intend to fit a nice big intercooler behind the grille, having the lowest profile set up possible is important. I did a load of searching for examples on google as well as on the forum and cam across a Buick EFI conversion dizzy. So took those as reference with me to Simon's place, within a couple of minutes he had drawn a sketch and started on the lathe.

Stated by cutting the top off of an old dizzy.



Then casually took a bar of bronze and made up a bush to support the central shaft.





He then took a steel bar to the lathe and made the cup, which was then attached to the central shaft. It was at this point that Simon chose the catchy name "The Butt Plug" for the cam sensor. haha. Though i do have to say that if that is what he chooses to put up himself, i would hate to see what a mess he has made.



Then came the master stroke of fitting the sensor itself in the cap that fits over the rotating cup. Of course again this started out as a 2 inch wide bar, and was turned down to fit. So kudos to the machining skills.



On a genuine note though the engineering skill to be able to take my concept and selection of pictures and turn it into a functioning item in 10 hours cant be overstated. (Though i spent so long in his shed, that i got told off by the misses).
I would highly recommend him for any small machining jobs that if your like me, you cant do yourself. For those that don't know him his tags madmk1, drop him a PM he might be able to help you out. Right thats the brown nosing done haha.

Hopefully it will work first time round.


In reply to the other comments, theoretically this target is possible, but yeah its going to take a few revs to get there and at the moment about a max of 20psi. As that is what the turbo makes before it gets inefficient, according to the fiat forums.
Anyway as long as i beat 180 i would be chuffed but 200 is the real target. The head is going to be the most limiting factor. Choosing to stick with a small bore casting in the 12G202, even with 1275 valves fitted will make for hard work. But if it makes the power, it will be pretty awesome.

#Tried It 2

Arghhhh I had to read that about ten times to realise what you had said!

On 29th Oct, 2017 Brett said:

On 28th Oct, 2017 Shauna said:
THE 998S ARE CUMING FOR YOU SIMON!

On 23rd Oct, 2017 madmk1 said:
200 bhp in a small bore 🤣🤣🤣

Shauna !!


im watching with interest, my mini when 998 was the most fun i have ever had in a mini

They don't die, they just get faster!