on monday Roundie (66 deluxe) goes in to get extractors... its a stocko 1100 and i was just wondering what gains i should get. not getting a dyno coz im on 1st year apprentace wages but what should i expect? not concentrating on power atm just getting her ready for the muster but when i collect some more $$$ what should be next on my list performance wise?

5HP maybe... not a whole lot just by fitting extractors......

It will be noticeable, however

5hp? thats not too bad concidering its a 10% increase from the shop figures of 50hp. by noticable you mean i will be able to beat the kids in my street on their deadly treddlys?

Depends how fast their little legs can peddle.


Better power all round will be noticed.
It will rev higher.
Sound nicer (if you are doing muffler and pipe too - limit this to 1.75" pipe MAX)

yeah i want to do zorst as well. why limit to 1.75??? will any bigger be too loud or a power loss due to lack of back pressure? how much will the larger exhaust set me back? might get a shinny centre exit muffler as well

Who is fitting the extractors?
The extractor-back system (including pipe, and bends required) should only cost around 400 dollars or so, with stainless muffler, tip(s) of choice, mounts of choice, etc.
From previous experiences, see if they can fit exhaust HANGERS, not the cotton reel mounts, which have a tendency to snap in the centre with spirited driving...

DEFINITELY don't go more than 1.75" on any standard motor... bigger you will go backwards - might as well have kept the stockie exhaust
Yes its due to the backpressure (you DO need it!)

to be honest with you willy i have no idea who is installing them for me! its a little gift from the old boy and will probably be done at a non-mini based garage so im guessing stock exhaust wll be on for a while. give it a month and i will have a scout around for someone who can find and fit the new system for me. is it difficult to source mini exhausts?

what are you implying???

yes, a bigger exhaust will reduce power
and any place can do an exhaust for a mini, should be quite cheap too

Dont take it personally

willy should of also mentioned that you can also run off the road and put the car onto its side after hitting an embankment whilst avoiding a car coming the other way when driving in a spirited manner

and if you have a big ass muffler fitted avoid driving over anything bigger than a 5c piece lying flat other wise you will fudge it as willy will testify to

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A stocko 1100 wont be anywhere near 50bhp.

Expext a stocko 1100 to be at about 30 to 35bhp at the wheels.

A modded exhaust (Perry extractors, 2" pipe to a 4" cannon,) and a modded cam got me to 44bhp at the wheels.

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No more Minis!......For now.

I think you'll struggle to see 2hp gain..? you'll THINK it has alot more power though..

Leaving the stock carb and exhaust on will pretty much restrict you like it was before the extractors. you're just placing something that flows better in between to restrictions at each end. (carb and exhaust)

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Starlet Conversion:
http://www.ausmini.com/forums/viewtopic.php?t=15484

If it's completely stock, it would have a 1.25" carby on it still. If it does, i'd put a 1.5" on it. Will be a cheap change and give you quite a bit better performance (if tuned right!). Will go very nicely with the extractors!

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Hey willy,

Any backpressure is a power killer. Why would you want it at all ? Please explain. The reason you keep the pipe to a certain diameter is that each slug of compressed exhaust gas is speeding along the pipe and creating a low pressure zone behind it. That low pressure zone helps suck the next slug of gas along thereby helping to extract all the burnt gases from the cylinders. If you go too big you lose that effect, too small and restrictive(not just the pipe but anywhere else in the system) and you lose that effect. Back pressure would mean that you would be trying to stuff burnt gases back into the engine. There is a mirror bounce effect that travels all the way back along the system to the carby to help suck in more fuel but with the 3 exhaust ports on a mini you get a jumble that's hard (IF someone has managed to do it) to tune for. That's where tuned length exhausts come in on racing cars. They are usually shorter in length and exit out the side. I think for a mini the best is about 24" with a megaphone end but I have been known to be wrong, ask my wife.

Cheers,

smithy

ok so i talked to the old boy and he said i will be getting the extractors and a 2" exhaust all the way through... not sure on the exact facts but i've asked for it to be centre exit. will the 1/4" difference be much of a problem in the backpressure department?