Short Stroke k1100 turbo spec and a couple of questions.
Turbo Mini Forums

So, having obtained a crank I am now trying to finalise the spec and seeking a little advice.

The bare bones of the engine will be and 1149cc engine obtained by.

+60 omega forged lightweight pistons on sc 6 inch rods.
Fully worked 70.2mm South African crank.
Centre main strap, with some swiftune thicker dowels to locate the caps and BMW oil jets.
K1100 head with LT cams.
Compression should be 9:1

Sh engineering very light flywheel, Straight cut drops and box, Quaife lsd and probably a 3.6:1 final drive.

I am looking for a 9700 rev limit and 18-20psi peak boost.

Turbo wise a gt2056 should extend the power band through to 9k rpm at such boost levels. 33mm k100 throttle bodies rather then a single tb should help low end throttle response. (tricky for space but got to be done I think)

My main hang up at the moment is exhaust manifold design. should the length of the primaries be a particular consideration given the rpm target? I would prefer to stick the turbo behind the block with no bulkhead mods to stay on the right side of the law, and also to help keep the centre of gravity down low, so some sort of knot like harry or matty looks likely.

For those that have fabricated manifolds, was science involved, or was it mainly just what could be made to fit?

Thanks

James

Edited by minimole23 on 15th Oct, 2013.

To be honest in a mini engine bay it's always a bit of a compromise. I kept mine near enough equal length and just tried to keep the bends and shallow as possible not to restrict flow too much. On the other side, you don't want to make it overly long and start losing too much heat.

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1/4mile in 13.2sec @ 111 terminal on 15psi

carefull with the K1100 head and 9.7k rpm. The max permissable engine speed for the K1100 is 8900rpm, and max continuous speed is 8500rpm

The K1200 on the other hand is 9400rpm max permissable engine speed.

Probibly to do with the valves and springs

Better use my k1200 head then with the lt cams fitted. didn't realise the spring rates were different

On 15th Oct, 2013 minimole23 said:
Better use my k1200 head then with the lt cams fitted. didn't realise the spring rates were different

Edited by Sprocket on 15th Oct, 2013.

sounds like an awesome build

just wondering if theres any reason that rs cams aren't used on an fi engine?

If I use both rs cams it probably wont wake up till 5k.

I would like it to be road usable.

A compromise may be to use an rs exhaust cam.

The K1200 valves are lighter, this is possibly the reason higher RPM's can be used if the springs remain the same.

Phil.

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You can always shim the springs to increase the range as long as there is room at full lift

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What about the gtb2256vnt or what ever it is on the ivecos? Ball bearing and vnt, still big enough for power too.

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

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I will keep things simple for the moment. The 2056 should deliver the goods, and If I'm sure there will be some scope to tweek cams, as I have all combinations. Its a light car, so even with the hot cams shouldn't be aweful at low speed.

Hopefully picking up a new 2056 on saturday if it is the correct unit, so can really get started.

Edited by minimole23 on 17th Oct, 2013.

A tip off a crank was going spare resulted in a trip to Brett Sims Motorsport today to pick this up.

Just realised this in still in the help needed section. Will start a show us yours thread once progress really gets underway.

Just something to consider which I've learned from having an s2000... A turbo will completely change the characteristics of a revy engine.. An s2000 will go to 9000rpm easy, but after a turbo is fitted there's no need to go over 7000, you've got peak boost by something like 3000 with a sensible sized turbo and quite a flat torque curv. So if you hold it in till 9000 rpm you land on the wrong side of the torque curv in the next gear, so it feels like power is dropping off. Basically what I'm trying to say is there's really not much point in doing this with a short stroke crank.. Unless u use a giant turbo maybe, which boosts late, making a million bananas at 9000rpm but needs a push start to get going lol

On 19th Jan, 2014 minimole23 said:
A tip off a crank was going spare resulted in a trip to Brett Sims Motorsport today to pick this up.

David.

That's interesting. Did you keep the same cam profiles when turboing?

It also sounds like your turbo is a little small, becoming a restriction after 7k. Like any engine, turbo engines have a power band, on NA engines this is usually defined by the cam profile. The cam profile is still relevant in a turbo engine, but the turbo spec is what really counts. To make the most of the S2000 engine I'd be looking at a turbo to make the most of the rpm available (at the expense of lower down power). you'll make 30% more power lb for lb at 9k compared to 7k. It seems you went the sensible route, rather than the power route.

Having driven the don, I can confirm that high revving 16v turbo engines work very well!

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

The Don is one reason I decided to do this engine, great inspiration. For me an 8k rpm engine is not enough. If theres not point revving over 8.5 etc then so be it, but with the right combination of parts 9 shouldn't be a problem. I will start off with the LT cams and change them for RS items if the power band is not sufficient.

Ideally it would have a rotrex thrown at it, but can't afford to do that. I will be doing as much work as I have the facilities to do to keep costs down, but Brett really does know his stuff. Some nice engines in the workshop.

doesnt the gt2056 have a really retrictive wastegate? making it spike a bit? i would think you could use a bigger turbo than the gt20 if your using 9000rpm+? my friend ran a gt25 (not sure on the wheel sizes) on a 1.3 8v peugeot rallye engine to 9000 rpm

Speeding is like masturbating, everyone does it, but not all of us film it and put it on the internet

[quote=fab,8th Oct, 2010]fuck off

Its easy enough to open the wastegate hole out if boost does creep.

There should be no requirement for a bigger turbo. It is only 1175cc.

Generally speaking at that stage yea, they use the same cams. I was after I was taken out in one that I learned all this.. I wanted to turbo mine so I arranged to speak to a guy that had done it and go for a drive. If power is the only concern then like u say a bigger turbo would make use of the engines abilities.. It was suggested to me that if I wanted to retain the character but just have more power then a supercharger would be better.

That said, I love home brew stuff like this. I'm really interested to see how it turns out. I'm turning my short stroker into a 16ver, but pure n/a, so hoping to achive an unusable power band up the top of the revs. I saw a video of a hill climb car once that had some part off a helicopter to keep the turbo on boost so it was ready from 0rpm, that's one way to get round the big turbo problem

I've been having some second thoughts about this now, especially having trawled through some of the rolling road graphs. I idea of 9k or 10k is long gone as an aspiration. Getting power still climbing at 7k seems to be more of a consideration.

First up lt cams on the bike make power to 7.5k so given the similar capacity this presumably is going to limit max power regardless of where the turbo starts becoming restrictive.

Other thoughts are that despite a gt20 being more suited to high hp/revving engines whether it will even be required over a gt17, given the 1bar boost planned at this stage, and will only serve to worsen bottom end peformance.

Hi guys, first of all Happy New Year.

I've been thinking for a while now on a project like the one in this thread, basically a turbocharged short stroker using an SA crankshaft with a 16v cylinder head.

What does it take to fit an SA crankshaft into a normal 1275 block ? Especially with regards to rods selection.

you need a set of 6" rods basically, the easiest solution is get a set from SC as they had some made for the SA cranks, ( presume they still have some)

Hmm... do you guys think it would become much more expensive to build a short stroke k1100 engine rather than a standard 1275cc k1100 engine ?

In doing a little bit of cost analysis, the only additional cost I forsee is the cost of buying H-beam rods if I go the short stroke route. Or am I missing something ? (although I must say that buying the H-rods would be around 400gbp so not cheap, but I'm hoping I will get those as the next Christmas present )