18 replies to this topic

[luismx123]

Worth?

 

Found someone selling a pair for 75€, need to be cleaned and refurb'd but im down for a bit of a challenge while my mini sits around... Is there anything to gain on a 998 carbing up? Got a SU4 on there now(stock one I believe)...

[nicklouse]

a single HIF44 is to much for a 998

[Minigman]

Way too much for a 998. Even one is a bit over the top unless highly tuned.

[WillCarter]

It would be worth buying them just to keep but they'd be rubbish on a 998

[gazza82]

That's B-Series territory .. MGB, etc .. you'll drown a poor mini in unleaded ..

[luismx123]

a single HIF44 is to much for a 998

 

It would be worth buying them just to keep but they'd be rubbish on a 998

 

Way too much for a 998. Even one is a bit over the top unless highly tuned.

 

What makes it too much? just that the hif44 or double 44s offer too much gas and airflow? or more than the 998 can use? or is there something negative....cus id think you can just make the bigger carvs let less gas through?

[nicklouse]

the port velocities will be way too low.  you would be likely to get less power out of the engine than is you had a single Hif38 on.

 

low port velocities tend to allow fuel to drop out of suspension (or is that atomization) so you get a very poor burn.

 

a single Hif44 if good for about 200BHP and is perfect on most big bore engines. a single Hif38 if perfect for just about all small bore engines. bigger carbs does not mean more of anything and most likely less power.

[luismx123]

the port velocities will be way too low.  you would be likely to get less power out of the engine than is you had a single Hif38 on.

 

low port velocities tend to allow fuel to drop out of suspension (or is that atomization) so you get a very poor burn.

 

a single Hif44 if good for about 200BHP and is perfect on most big bore engines. a single Hif38 if perfect for just about all small bore engines. bigger carbs does not mean more of anything and most likely less power.

 

so that means getting a single hif38 and maybe vizarding it would give max performance for my 998 over my hsu4?

[Turbo Phil]

As Nick said, to big a carb will reduce port velocities and as a result volumetric efficiency (cylinder filling) suffers. Engine airflow demand dictates how much carb you really need.

Phil.

[nicklouse]

 

the port velocities will be way too low.  you would be likely to get less power out of the engine than is you had a single Hif38 on.

 

low port velocities tend to allow fuel to drop out of suspension (or is that atomization) so you get a very poor burn.

 

a single Hif44 if good for about 200BHP and is perfect on most big bore engines. a single Hif38 if perfect for just about all small bore engines. bigger carbs does not mean more of anything and most likely less power.

 

so that means getting a single hif38 and maybe vizarding it would give max performance for my 998 over my hsu4?

 

You may already be at max for the engine an HS4 does not add much to a 998 there are other things that need work first.

[Retroman]

 

the port velocities will be way too low.  you would be likely to get less power out of the engine than is you had a single Hif38 on.

 

low port velocities tend to allow fuel to drop out of suspension (or is that atomization) so you get a very poor burn.

 

a single Hif44 if good for about 200BHP and is perfect on most big bore engines. a single Hif38 if perfect for just about all small bore engines. bigger carbs does not mean more of anything and most likely less power.

 

so that means getting a single hif38 and maybe vizarding it would give max performance for my 998 over my hsu4?

 

 

   Firstly the twin HIF 44's are way to big and only have an application on full race 1330 + cc engines

 

To gain any significant power or torque on any standard Mini engine a cylinder head and cam should be the priority

 

Changing to a HIF38 and vizarding it along with the manifold will make a small gain, much less than a modified head or cam.

 

To make real gains which you can feel it should be; rebore, head and cam then carb or all 4 at once,.

 

Petrol is using one of my vizarded HIF38's and stubstacks for his 998 screamer

 

The carb has to be matched to the output and air demand of the engine

 

Your 998 will only be making about 40 HP and a std HS4 is good to about 60 so its 'matched' to the output of a standard 998

 

[luismx123]

 

 

the port velocities will be way too low.  you would be likely to get less power out of the engine than is you had a single Hif38 on.

 

low port velocities tend to allow fuel to drop out of suspension (or is that atomization) so you get a very poor burn.

 

a single Hif44 if good for about 200BHP and is perfect on most big bore engines. a single Hif38 if perfect for just about all small bore engines. bigger carbs does not mean more of anything and most likely less power.

 

so that means getting a single hif38 and maybe vizarding it would give max performance for my 998 over my hsu4?

 

 

   Firstly the twin HIF 44's are way to big and only have an application on full race 1330 + cc engines

 

To gain any significant power or torque on any standard Mini engine a cylinder head and cam should be the priority

 

Changing to a HIF38 and vizarding it along with the manifold will make a small gain, much less than a modified head or cam.

 

To make real gains which you can feel it should be; rebore, head and cam then carb or all 4 at once,.

 

Petrol is using one of my vizarded HIF38's and stubstacks for his 998 screamer

 

The carb has to be matched to the output and air demand of the engine

 

Your 998 will only be making about 40 HP and a std HS4 is good to about 60 so its 'matched' to the output of a standard 998

 

 

 

YA good infos! I might be doing a headswap over winter, but im saving up for a new interior and other cosmetics so was wondering if just swaping out the carb for under €100 or vizarding it would throw enough boost out to get me through a few more months without wanting to do the head/cam rocker swap. My engine is really fresh. under 70,000km and was driven by a granny for more than 60,000. once i hit 100k id definitely do a cleanup and what have you... and stuff like sanding the intake/fixing up a carb or w.e is fun to do and works well as a weekend+ project without getting really dirty and frustrated that my hulkhands dont fit anywhere in my mini :/

[nicklouse]

 

 

 

the port velocities will be way too low.  you would be likely to get less power out of the engine than is you had a single Hif38 on.

 

low port velocities tend to allow fuel to drop out of suspension (or is that atomization) so you get a very poor burn.

 

a single Hif44 if good for about 200BHP and is perfect on most big bore engines. a single Hif38 if perfect for just about all small bore engines. bigger carbs does not mean more of anything and most likely less power.

 

so that means getting a single hif38 and maybe vizarding it would give max performance for my 998 over my hsu4?

 

 

   Firstly the twin HIF 44's are way to big and only have an application on full race 1330 + cc engines

 

To gain any significant power or torque on any standard Mini engine a cylinder head and cam should be the priority

 

Changing to a HIF38 and vizarding it along with the manifold will make a small gain, much less than a modified head or cam.

 

To make real gains which you can feel it should be; rebore, head and cam then carb or all 4 at once,.

 

Petrol is using one of my vizarded HIF38's and stubstacks for his 998 screamer

 

The carb has to be matched to the output and air demand of the engine

 

Your 998 will only be making about 40 HP and a std HS4 is good to about 60 so its 'matched' to the output of a standard 998

 

 

 

YA good infos! I might be doing a headswap over winter, but im saving up for a new interior and other cosmetics so was wondering if just swaping out the carb for under €100 or vizarding it would throw enough boost out to get me through a few more months without wanting to do the head/cam rocker swap. My engine is really fresh. under 70,000km and was driven by a granny for more than 60,000. once i hit 100k id definitely do a cleanup and what have you... and stuff like sanding the intake/fixing up a carb or w.e is fun to do and works well as a weekend+ project without getting really dirty and frustrated that my hulkhands dont fit anywhere in my mini :/

 

no. as stated a carb can not give more power unless it is restricting the engine. the current is more than enough for your engine and a single HIF38 is more than enough for 99.9% of small bore engines.

[DeadSquare]

In the early/mid 1950's, the body of an 1 1/8" SU was the same as an 1 1/4", and I think it might have been Alexander Engineering who ran a tapered reamer through the 1 1/8" carbs, down the twin manifold and into the head, thus perfectly matching each joint.

 

The gradual restricting of the airway increased the gas speed and considerably spread the torque band with a hot cam like a 544, and was very effective on a 997 cooper engine.

[mini13]

how do you run a reamer through a carb with a bridge in it?