30 replies to this topic

[Tomf]

I have a 998 engine and i was wondering if the performance would be much different if i put twin 1.5 su carb instead of a single 1.5 su carb.

Hi i have a standard 998 engine and i am going to change the carb and i was wondering if a 1.5 twin su carb would perform better than a 1.5 single su carb.

[miniboo]

twin 1.5's will drown it.

twin1.25's will give it much better drivability

[Tomf]

ok so what would be better a single 1.5 su carb or a twin 1.25 carb

[miniboo]

twin 1.25's personally

[minislapper]

I'm sure there was a discussion about this recently. Try doing a search and seeing what comes up.

Asking which carb is best is irrelevant in terms of performance etc as there are many factors which influence this. Just changing the carb will not make a difference for the better.

What the car will be used for is one consideration. Is it going to be a daily driver, track car etc etc.

The condition of what you have already is a major factor, ie trying to tune a tired engine is just throwing money away.

A different carb needs to be thought about in relation to other components too, ie manifolds/exhausts to name but a few.

Have a read of some of the previous discussions about tuning etc. There have been some good points made in the past.

[Tomf]

Ok thanks for the advice, but would there be much of a difference between the two carbs.( single 1.5 or twin 1.25)

[Guess-Works.com]

all depends what the carbs bolted to.... if it's a std 998 then I'd stick with the single...

If you had head work, bottom end changes, new cam etc etc then yes potentially the twins will improve matters.

[minislapper]

Carb discussion

[*DJH*]

I Aggree With GuessWorks, Twin SU Setup Will Seriously Hamper The Performance, Not Imporve It. Since I Race A 1000cc Mini A Single Su 1.5" Is Much Better. With The Correct Setup Mine Out Accelerates A 1275 - 1310 With A Webber DCOE 40/45!

[Jimmyarm]

With The Correct Setup Mine Out Accelerates A 1275 - 1310 With A Webber DCOE 40/45!

Any chance of sharing this setup !

[Tomf]

Ok thanks what is the best thing i can do to gain performance.

[*DJH*]

Yeah I'll Have To Dig The Paper Work Out From The Garage.
I Know That To Acheive This You Need A Different Needle, Spring And Air Filter. The Timing And Air - Fuel Ratio Has To Be Changed.
(So Basically The Car Runs Like Sh#t At Low Revs And Uses Copious Amounts Of Fuel, But Flies At High Revs)

[Tomf]

Is there anything else i can buy to gain the performance. what would do the biggers change to the performance. at the moment i have stangerd everything

[miniboo]

Have just noticed that you have a city e which will mean it has a 2.95 diff.

best thing to make it nippier is give it a good service and then maybe looking at gearing a different diff.

this will improve you wacceleration but lower the top end speed. will make it a bit noisier and higher revving on the motorway tho

[*DJH*]

Ok thanks what is the best thing i can do to gain performance.

Well The Common Way People Add Performance Is;

Stage 1/2/3/4 Kits

Some Other Ways (Expensive) Are;

Lightened Panels / Weight Removal.
Lightened Flywheel / Clutch Plates.
A Good LSD (Limited Slip Diff)
Straight Cut Gears (So You Can Have An Efficent Way Of Laying The Power Down)
Improved Air Flow / Induction.
Hose Upgrade (So They Can Hack The Abuse)
Serious Engine Engineering Mods.
Flow The Head / Port Polish.

GuessWorks Might Agree With Me On This, That Most Torque Is More Important Than Horsepower For Minis.