1380cc or 999cc tubo?
Turbo Mini Forums

Hi all, you may have been reading the topic in the for sale section about my decition on what to do for next years race engine.

I have currenlty got a 1380cc 16v K Head engine that is supposed to be producing 172bhp and i think 134ftlbs

Next year I obviously want more power etc to hopfully allow me to contend for the championship.

So the question is do I develop my 1380cc more (Not sure theres a whole lot left to do)

Or do I try and develop a 16v twincam engine from a 970 (or similar custom) crank. And then turbo it?

The reason for this is that the rules say if forced induction is used then capicity is X 1.4, so I must have less than 1000cc to stay in my class.

In my head I think that 200bhp and 150ftlbs is possible with this set up, feel free to shoot me down but lets talk about it, after all thats what forums are for.

Discuss :)

What would be interesting is if you took your car to the TM RR day on 17 steptember. Our 998 turbo hillclimber will be ther and it'd be interesting to see how they compare on the same rollers on the same day.

I agree that 200 is possible, but possible and drivable, not sure. we're aiming for 180, and I'm confident it'll be way faster than any 1380 around at that, as it's as quick now with around 150.

see what others think, because I'm obviously biased in my opinion.

Edited by wil_h on 29th Sep, 2009.

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

I have thought a lot about this myself. As I belive I have found the limit of my car, and any more power is not making my lap times quicker, but slower. I have often thought about a small CC short stroke engine, keep the 1275 block, and short strock crank. If I can get over 250bhp from my 1310cc engine, I'm sure with some head work, and the right turbo over 200bhp is possible from a 970 engine. I think also when you have 200bhp gearbox and clutch issues are not so much a proplem. Personally I'd be going for 9:1 compression ratio, and 20psi of boost, using a modern GT ball bearing turbo

Team Racing

I've attached the calcs that I posted on the other thread.

This is the "design" spreadsheet that I developed for my 980cc K100 build, but with the boost increased from 10 psi to 20 psi. No other changes were made. So in theory, you could get around 200hp from 1 litre.

However, you are going to need a high VE at 8000 rpm to do it. This will involve a very good head and cam combination.

There are a number of short block options:

1. Standard 998 configuration, limited to 5 port head but numerous cam options.

2. 998 block bored +0.120" and 850 crank. The K100 8V head will fit on this, so enough flow for 200hp but limited cheap cam options although standards cam may be fine. Piper or Kent will regrind to any profile for £200 ish. The crank is going to be the limiting factor in my opinion.

3. 970 crank in 1275 block, special rods and crank. Use the K11/1200 16v head and cams. Probably the most robust, but the most expensive.

Turbo wise, all the ball bearing turbos are going to be a bit on the large side, but maybe the GT1752 or GT2056 would be fine.

Attachments:

9.98kb

Edited by Paul S on 29th Sep, 2009.

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."

Ok, im thinking maybe the 970 crank, or billet replica and 1275 block, with a K1200 head. (lighter valves, higher rev limit)

Am I right in thinking to get a turbo to work for that bigger rev band (say 3000 to 10,000) is going to be hard task. You will either get one that works well low down but rubbish up top, or one that will not come on boost till silly high rpms?

That would be the strongest solution.

We just need a price for a 62mm stroke billet crank and some 6.0" long H beam rods. They're £1000 for standard size, so will not be cheap.

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."

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."

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."

Yer im not sure i believe them, its nice to say thats what I have got but there is no point lying to myself.

I think I have a genuine 150bhp.

Ok, this may sound stupid but to overcome the turbo size for revs problem. How about there larger size turbo to give boost up top. Wont come in till 5000rpm.

But then to fill the void below 5000rpm, a supercharger aswell?

The problem with a supercharger is that it doesn give as high boost up top, and the problem with the turbo is it doesnt give it down low... so put them together and you have usuable power throughout?

Am I right?

Ah, another of my flights of fantasy!!!!

Give me a spreadsheet and I can do anything :) I did this one a couple of years ago when I was quite naive.

Calcs attached for a supercharged and turbocharged 998 using a M45 and Gt1752 with twin intercoolers to give an efficient 31 psi boost !!!

200hp at just 6000rpm

I have all the parts in the workshop, but reality has recently put this one to the back of the engine project list.

Attachments:

10.15kb

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."

Looking at your first spread sheet and then at the GT17 (guessed) map http://www.turbominis.co.uk/forums/attachments/140552-1.jpg at the required airflow you are still in a reasonable efficency zone (this has been proved by Robert at least).

I don't understand your pressure units though Paul, but even so I don't see why a single GT17 woldnt work and give power fron 4k (which is where I get it from) all the way to 10k.

What pressure ratio do you need for 200bhp on a 998? I haven't got my spreadsheet to hand to pop out a number.

Edited to change 2000bhp to 200bhp, before any pedants give me a fucking silly answer like a million psi!!!

Edited by wil_h on 29th Sep, 2009.

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

Well, on the basis of the various calcs I have done, the boost required to acheive 200hp from 1 litre, depends on the revs.

At 6000rpm you need 31psi. At 8000rpm you need 20psi.

I would not go any higher than 8000rpm for peak hp.

I dare say the GT17 would do it, but looking at the estimated map, I doubt that you would get a full 20 psi boost until 5k, but that's only my theory based on the estimated map. In practise you may have experienced otherwise.

I've since bought a GT2056 and although the numbers appear to suggest a similarity to the GT1752, it looks quite different, particularly the turbine wheel.

Edited by Paul S on 29th Sep, 2009.

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."

is the fule limited to only gasoline? Ethanol can boost 20 to 30% more power.

If you are inzane you can use nitromethane. dobbel the HP.

I would say forget the idea of turbo and supercharger. It is far to complex and heavy and will need so much development. If the GT17 works from 4or 5k to 10k then that sounds good to me. Match that with the right gearbox and final drive and you will have something different and powerful.

I have to say though that our bottom end is about £600 worth, the head is about £400 worth and all the other bits and bobs don't add up to much. I would guess £2k would build our engine from nothing. This is a reliable 150bananas 140 torques with the potential for 180+.

We are at Curborough on 11 October, if you are anywhere close I would say pop along and have a chat with us and see the car go, I guarantee that you will be impressed buy what we have for the money.

Edited by Ben H on 29th Sep, 2009.

http://www.twin-turbo.co.uk
http://www.hillclimbandsprint.co.uk/default.asp

A man without a project is like a like a woman without a shopping list.

I thought the whole idea of the GT17 was to get a quicker spool up lower down? or is this just the case on 1275's?

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

Im at curborough on the 3rd if you wanna pop over?

Edited by 01smartc on 29th Sep, 2009.

Im at curborough on the 3rd if you wanna pop over?

So supercharged and turbo wouldnt work well?

O and yes im limited to pump fuel

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."

http://www.twin-turbo.co.uk
http://www.hillclimbandsprint.co.uk/default.asp

A man without a project is like a like a woman without a shopping list.

Yer would be nice to race you, im the only one in my class on sat.

Erm not sure of my 1 lap times cant remember, but about 3 weeks ago I did a 62.42 on the double lap.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?Vie...em=220486575927

Yay! Cheers mate, doesnt say what is ground to tho?

well as it says unused new old stock it should be unground.

mabe the pittiong would polish out, mabe it' need to go to -10