Stateside 998 Build Thread With Updates!
Turbo Mini Forums

Hi All,

I'm located in the USA and have 1979/1985ish (franken car) left hand drive Mini 1000. These are pretty rare over here and I'm having tons of fun with it. In an effort to find a project to take up all my time I'm looking to build up a turbo engine for the car. I'm going turbo since I work as a manufacturing engineer making turbo impellers, seems like I may as well have a turbo in my car. That and I want some pep (and, being honest, the sound!)
I got a spare 998c A+ engine. 1275 is very hard to find here and even the 998 is rare. I've started taking the engine apart for a full rebuild and modifications. There are some things that will need replacing and I'd like to try my hand at building some components, it seems a shame not to use the hundreds of 5-axis CNC machines I've got here for making silly Mini parts.
At this point, I'm hoping for a review of my spec/plans and any input you might have. Sourcing parts in the US is mighty difficult and shipping from the UK is very expensive but I think I'll have to 'nut up' for some things.

To the build. I'm looking for a solid project that will give me some fun speed to play with.

Block:
998c A+ block. How much overbore is recommended? Was looking at +080? Dished pistons seem hard to come by
Replace main bearings as they are very worn
Not sure I will try and wedge the crank or not. Might need re-grind
Cam is totaly undecided
Looking at building an alloy timing cover and maybe doing belt

Head:
Very undecided. I'm thinking a 12g1316 as these seem very similar to the 940 but with more material for skimming. Also, very available in the states (MG midget and Sprite).
Recommendations on valve sizes?
Hoping to build an alloy roller rocker. Will stick with 1.3 or 1.35 for 998 happiness
Will probably do some light porting and cylinder enlarging

Gearset:
Stock gearbox rebuild with a X-pin Diff

Clutch/Flywheel:
Haven't really gotten here yet

Carb:
HIF6 or HIF44, might need to source from UK. The HIF4 is available here but I think I'm going to want the larger carb.
Are there other options?

Plenum:
Probably metro turbo which I will also source from the UK.
Are there any alternatives to this?

Turbo:
T2 or some variety on a custom manifold that will hopefully not require bulkhead mods.

Looking for input or critiques. Hoping to get the short block done then move on to the head and then the gearbox. I'm definitely into doing modifications and open to suggestions

Edited by seahuston on 19th Jul, 2015.

It all sounds fairly sensible.

For the head you need to think about the chamber size before you get it skimmed. If the chamber is fairly big, you might get away with flat top pistons. If you are putting a large bore head on a 998 you will need to pocket the block to allow the valves to clear. There's a drawing somewhere on here.

Clutch - A standard Metro Turbo verto should do the job.

Carb needs to be a hif44 so you can seal it up for boost.

For the Turo, look into the GT15 range. smiliar to T2 in size, but more modern design. Not that that would be an issue for you.

Oh and Hello

Thanks for the heads up. Glad I'm at least started out on the right track.

Does it make sense to try and overbore the 998 to the max? I know that max bore is the trend with N/A but not sure with turboc. I think I'd probably need to get the head first and figure out my CR options.

I mention the skimming because it sounds like the 940 is a good head but doesn't have a lot of rooming for skimming if needed. The 1316 is very similar but with extra meat. Does using a big bore head on a 998 make much sense? I know it's possible but...

Here is the post regarding the pocketing, I should be able to handle the pocketing. http://www.turbominis.co.uk/forums/index.php?p=vt&tid=485966

Regarding the carb, this site has some info but I'm not sure of the reliability of the information http://www.triumphexperience.com/article/h...ough-an-su.html

I haven't gotten too far in the turbo selection process, just know that I'm hoping for the T2 size range. I'm not racing so it'll be nice to have the spool at a bit lower RPM.

HI!

have a look at this site it may help out with a few questions http://www.turbo-mini.com/62147.html

Done now needs redoing lol

I would say leave it at std bore size if you can, the std 998 flat tops are sturdy, (ok for 15-20psi) if you are looking for extra capacity then you may as well go for a 1275 rather than start boring IMO.

head wise, the best thing is the 998 cooper 12G295, but these are getting scarce. the next best thing is a 12g940(or equivalent) a bit of flow work would be nice bit not essential, I'd stick with the std valve sizes too.

any HIF6 can be rebuilt for use on a turbo, there is info on here somwhere (probably in the FAQ section) for the plenum the best thing is use the metro one as it has a restrictor ring in it to make the carb work under boost, you can probably pick one up on here with any other bits, we have a few USA.

Hi there,, if you want any parts or help from the UK drop me a PM

I have enough bits and bobs for a HIF44T to be assembled from (standard metro turbo fitment). I also have a plenum, and a spare Manifold, and am in custody of a new and un-used GT15 that the owner wants me to sell.
I am also stateside. Shoot me a PM if you are interested.

Edited by TurboDave16V on 15th Nov, 2013.

TurboDave: PM sent. Thanks!

Joe C:
Regarding overbore, I figured it might make sense while it is out. If the gains aren't to be huge I won't spend the money. I think I could do most of it at work but there is still the expense of the Pistons.
I haven't check the bores yet so it's not clear if it will need a rebore.

I'll keep looking for the 12G295. These were used on the MG Midget as well but they are a slightly different head than the cooper. I have seen some on eBay but they are pretty beat.

I think I had the idea that this would be a huge project with lots of modifications but it sounds like, at least with a 998, a straightforward rebuild is my best bet with bolt on mods as available.

I've read through the 20 hour turbo a bunch of times. That is kind of the site that got me started.


I got my engine this past weekend and started the tear down during the week. Updates so far:

Engine in the back of my Golf. Ended up separating the gearbox in order to be able to lift the engine out with my GF. Also got a set of new tires and a chrome dash!



Block on my the bench



Ordered up some new tools to make life easier. I'm doing my best to take my time so that I do things correctly and don't mess stuff up. I have a habit of not being patient, using the wrong tool or rushing and then breaking things.



Dropped some parts in the washer for a few days.



Serious pitting/grooving on the crankshaft bearing journals. Definitely going to need a regrind.

Came back from the machine shop today and am a bit discouraged with the scope of work/shape of the engine.
The piston ring clearance is way over which means new pistions and a rebore. I was hoping to save some money and keep with stock.
Crank definitley needs a regrind which is more money than I expected (~90GBP).
Need to do all new bearings and oil pump and the flywheel housing is cracked (should be a weldable repair).
I'm thinking I'll keep plugging away at it but seems like a main part of the project is just the financial outlay.
As I keep working on the project can anyone help with discussion of ideal static and dynamic compression ratios. This will help a bunch with piston, bore and head selections.

I pay about £10 per journal for grinding in the UK.

Back at it:
Spent some time to calculate and play with the compression ratio calculations and I'm realizing the 12g940 head will not work easily with flat top pistons. I would be purchasing this head with the chambers already opened to around 24cc.
Looking at a .020 overbore at least. I estimated/guess at a few numbers which I won't have until I start the build. I'm aiming for a 9.0:1 compression ratio which sounds like it will offer some freedom to play with boost and not worry about detonation. I'm not planning on anything extreme, probably around 7 PSI and maybe push 10 PSI but I definitely would prefer to not blow up my engine.
Here are the calcs:
Swept Volume (+.020):253.51

Gasket Volume:3.48
Chamber Volume: 24
Piston-Clearance V (.002" clearance):.17
Ring Land V: .78
Pocket Volume: 1
Piston Dish: 0

Total Chamber V: 29.43

Compression: 9.61:1

This seems pretty high too me but maybe it'll be fine. I'm looking for advice here. I can't seem to get a good lead on dished pistons but it sounds like I can dish the flat pistons slightly without issue (?) I only need about 3cc of dish.
The other option is to look for a 12G295 head but I've found a good lead on the 940 head with hardened seats and all. The 295 is much more difficult to find and more expensive.
Help? I guess I'm wondering what my options are here. Piston choices/dishing? Am I up the wrong path with the head?
Without the option to skim this head I feel like I might be playing with a pretty small margin of safety.
Thanks.

I'd definately start the search on a 12G295. Check on the minimania forum, to see if anyone there has one. For what you are after, a 12G295 would be pretty much ideal I'd have thought.

Don't forget, assuming it hasn't been wildly skimmed, the 940 will go out to 28cc.

WWW.TURBO-MINI.COM

295 is the way to go.

Roger that, looks like the 295 is the next step.

(I'm not dead yet!)

An update for all of you and, of course, a need for some advice.

[In Short]
Still need:
Turbo
Cam (maybe)
Exhaust manifold (will end up fabbing)
Megajolt

Work Status:
Entirely in pieces
Block and head at machine shop
Waiting to order rebuild parts for carb and gearbox
Cleaning

I'm still moving along with the project and getting things together. It's a fun adventure finding/meeting all of the Mini enthusiasts in my area and farther.

I've pretty much gotten everything taken apart and am in the process of cleaning.

I mag tested my crank and found a crack so I went out hunting for parts. Found a guy about 3 hrs from my place with multiple BARNS full of Mini stuff. Bunch of fun stepping over engines looking for things but sadly, he is a bit of a hoarder/schemer so the prices weren't too great and he didn't want to get rid of much. I did however find:

HIF44 Carb and Intake
998c Short block with good crank
Flywheel housing (mine was cracked)
NOS Minispares Timing Belt kit, not sure if I will use this though
NOS +040 pistons
Sump Gaurd
Idler gear

I've got my gearbox totally in pieces and found that my first gear was missing some teeth so I will replace that. Everything else looks in good shape but that might explain the gouging in the crank.

I located a 12G295 head. For those hunting (maybe just in the states) the Austin Healy Sprite had this head and there are quite a few here.

The block and head are the machine shop. Reboring to +040 to clean up the bores, installing hardened seats and doing any other recommended work.

I've located a fuel regulator, pump, plenum, drain plate and maybe a turbo and cam (thanks Dave!) and waiting on shipping.

To save on shipping I'm racking up a big Minispares cart and waiting to pull the trigger. The list keeps growing and growing.

I'm still, potentially, hunting for a turbo. It sounds like the GT1548 is a great turbo for this car. Only issue is that I can't find them off any used cars so I'll be buying new ($$). I'll force myself to resist the eBay china crap.
Is upgrading the cam worth it from stock 998? I'm getting sucked into the spending money because "I want to do it right the first time" which is making the budget grow quite a bit. Weighing the value of each upgrade.

That's the update for now. I'm looking forward to sharing pictures and updates soon.

An MG metro cam would be good with a 998.

Roger that, I've read that is the best cam for the engine and starting up the hunt. I guess my major question was how much difference it will make? It seems though, that it may be one of those, "do it right first" kind of things that I should just replace it and be done.

For the turbo I'm looking for the GT1548 at the moment but maybe (still researching) a GT12 for something different. I think though, it will be not big enough.

Edited by seahuston on 6th Feb, 2014.

The MG is a good cam but the best cam is the MD274. 112 LSA is an obvious improvement over the MG at 107.5.

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 all for the advice. Roger that on the MD274 cam, sounds like a worthy upgrade coming from the "Factors affecting performance" thread.

I'm queuing up a big order from Minispares and they are out of stock on the A+ center main bearings. Minisport has the Glacier and Vanderall, any recommendations on the bearings to get?

Also, I picked up a NOS Minispares belt drive conversion kit. It looks pretty nice but I'm heard some mixed reviews on these, should I just go standard duplex and try to sell this?

Edited by seahuston on 9th Feb, 2014.

I used a iwis simplex chain.

I used ACL bearings.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I'm not sure anyone makes performance 998 A+ main bearings anymore.

So I've used pre-A+ mains in my last two engines. However, you need to machine a slot in the cap:

Edited by Paul S on 9th 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."

Wish I'd looked at this sooner! Lots of helpful stuff for doing a 998, will be following this one (:. Must suck that there aren't many parts around!

Edited by Shauna on 9th Feb, 2014.

They don't die, they just get faster!

Paul:
Thanks for the tip and the pictures, I can certainly pull that off

Shauna:
I'm getting better at sourcing parts stateside but it isn't easy. The big bummer is the increase in budget. With shipping added in, things like the affordable Metro cam are just as much as Kent