big bang mini engine
Turbo Mini Forums

hi all.
i have been toying with the idear to make a big bang mini engine. the idear behind this is to fire two cylinders at once 1 and 4 2 and 3 all i need is to get a camshaft made. and wasted spark. i have seen this been done to bike engins and it works. but will it work in a mini engine is my question.

Think of the strain it will put on you 3 main bearings??

You could make it work I suppose, but im certain the main bearings would not like it...

i would hate to think of the amount of flex that the crank would have with both cylinders firing. I dunno about the thinking behind the moto gp engines with the big bang. The best thing to do is to try it!!

i thought of this about 5 years ago , but a stayed in bed untill the thought pased,


carl

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I nominate Stu from Cornwall or Peter1071s to answer this. LOL!

Seriously - those two will probably give a better answer than anyone else on this site as to the merits - if any - for such a radical unit.

D

I thought it was only on 2 stoke motorbikes

Metro turbo weekend driver,Mini turbo in the making again!

yeah didnt they do this on 2 stroke v twin motorbikes to improve traction?

if only i didnt throw out all my old performance bike mags i could of given a lesson on this

Hi,
No, they run big bang on the four strokes too. The idea being it gives the tyre chance to get a grip inbetween the two power pulses as opposed to a continuous stream of pulses, causing it to spin up.
Cheers,
Gavin :)

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in theory could this help the clutch grip? or would the massive powerstroke/shock just worsen matters?

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

I guess the question you have to ask is what is the benifit? The power of the engine is determined by how much fuel you can get in and out (roughly speaking.) So you are never going to get more power this way. Also if you use a 5 port head I would think you are going to get less, especially on cylinders 2 & 3.

Nice sideways thinking though.

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Worth trying on a 5 bearing engine, wouldn't bother on a 3. Especially on a 3 that is running close to it's limits on a powerful motor.

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

This could resolve the port robbing issue!

The inlet valves on each port would operate 360 degrees apart, instead of the normal 180.

EDIT: Wrong again - I'll just shut up.

The outers would rob the inners instead, if you went 1&4 then 2&3.

Edited by Paul S on 20th Sep, 2006.

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 me the idea was to help with blowing head gaskets between 2&3 , that being if it did blow it wouldn't matter,lol. but with lots of nitrous entering the equasion it would prob need an extra big journal mains crank and a whopper of a centre cap.
other than that i think my car would sound very strange with two engines banging away,lol.

carl

WWW.FORCE-RACING.CO.UK PLEASE CLICK HERE

try to make a camshaft first, and if you do that, tell me how you did it. I want to make my own if i can.

i thought this aplied to two stroke motors. Cant see it working on a four cylinder four stroke, it would run very rough.

Edited by Sprocket on 21st Sep, 2006.

Well if you look at like a 2 cylinder 4 stroke then it makes sence. From what I understand (very little) the bigbang motorbke engines fired all cylinders on the same stroke, not at the same time though.

Leadfoot there are plenty of people out there that will grind you a cam, you just need the money.

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

roughing it out on a lathe first could save you some wedge, then take it to a grinders. nice bit of offset turning.

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

What can a custom cam cost?

Ok there seem to be mixed opinions. But I would like to try this. So who out there will grind me a camshaft. Even if it doesn’t work at least I have tried. I work at a mini centre that has a rolling road so I can build the engine and test it and it wont cost me that much its just the camshaft I will need. I have seen it done on an autograss car with a bike engine and it won most of its races. It runs and sounds like a v twin. I now a mini engine is in a different league but if you don’t try you don’t know?

Hi,
I would imagine, never asked though, that either Piper or Kent should be able to do the job for you.
Cheers,
Gavin :)

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WB/EGT gauges. Click here for customers write-up

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I would talk to Newman cams...

Alex

AlexF

Edited by Jimster on 22nd Sep, 2006.

Team Racing

Well from previous experience Piper and Kent can't grind the same profile on 4 of the 8 lobes on a camshaft.

Alex

AlexF

I thought newman made the shrick ones?

No idea Alex....

But all 3 can't be that bad else they'd go out of business....

Alex

AlexF