35 replies to this topic

[Minigman]

Maybe I’m being stupid here, but what’s the advantages of shorter or longer ram pipes?

Fitting twin HS4s so looking for suggestions and options for filtration on a nicely built 1330 fast road engine

[nicklouse]

some are good some are not so good.

 

it all comes down to what induction length works best for the build. induction length between valves and carb is only one side the length before the carb has results as well.

 

but as you are putting HS4 on a road engine I would just fit stubs  and nothing more. as you are mainly wanting torque for a road build.

 

well I would not as I would not bother with the twins but that is just me.

[Minigman]

I would have run a hif44 but it’s a 74 and I wanted something more period. Not a Weber either.

[Minigman]

some are good some are not so good.

it all comes down to what induction length works best for the build. induction length between valves and carb is only one side the length before the carb has results as well.

but as you are putting HS4 on a road engine I would just fit stubs and nothing more. as you are mainly wanting torque for a road build.



well I would not as I would not bother with the twins but that is just me.

Stubs with what for filtration?

[imack]

I'm running MED's stub stacks and ITG filter setup on my 1380

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[Turbo Phil]

I flowbench tested this a couple of weeks ago, showed a decent gain in flow and is designed to fit under a K&N cone filter. Available for the 1-1/2" and 1-3/4" SU.

 

Different length ram pipes can be used to tune the inlet length and are used to alter the torque spread of the engine. Tuned lengths can have quite a dramatic effect when done correctly.

Phil.

 

Edited by Turbo Phil, 07 December 2018 - 08:21 PM.

[luismx123]

I flowbench tested this a couple of weeks ago, showed a decent gain in flow and is designed to fit under a K&N cone filter. Available for the 1-1/2" and 1-3/4" SU.
 
Phil.

Mine is arriving tomorrow. Dave's a good guy. Was great doing work with him.

What's wanted to know was when fitting the stub, should I change anything on the carb? It's my first performance upgrade on my 998.

[DeadSquare]

In the 60's, somebody, Like "Birds Custard" made a 'fruit salad jelly with topping' and sold it in a trumpet shaped plastic container.

 

The container was about 5" tall and with the bottom cut out, was a friction fit in an 1 1/2" SU.

 

I tried it for a joke. as a talking point in the paddock on a Mini se7en engine, and at about 6,300 RPM you could notice the engine 'crackle'.

 

I probably imagined that it went better, but one doesn't spend much of a race in that rev band.

[Retroman]

Maybe I’m being stupid here, but what’s the advantages of shorter or longer ram pipes?

Fitting twin HS4s so looking for suggestions and options for filtration on a nicely built 1330 fast road engine

 

As you probably know the cone filter is a compromise on power, and a long way from period

 

Our stub stacks inside a round K&N

 

10% off for TMF members

 

http://www.retromini...roducts_id=1241

 

[AlexMozza]

I have a 1330 with twin HS4s. Both with 40mm ram pipes. Runs very well with excellent torque. I found that it cleaned up the power and torque curves compared to running without any. Also gained a slight top end too.

1330 with SW5.

[Mini Manannán]

I flowbench tested this a couple of weeks ago, showed a decent gain in flow and is designed to fit under a K&N cone filter. Available for the 1-1/2" and 1-3/4" SU.

 

Different length ram pipes can be used to tune the inlet length and are used to alter the torque spread of the engine. Tuned lengths can have quite a dramatic effect when done correctly.

Phil.

 

 

Who's is that Phil?   There's a lot going on the face of it; there's gains to be made there!

[DeadSquare]

In the late 1930's Maserati had a V block system so that they could slide different length Ram Pipe/ Trumpets in front of the carbs of their straight 8 on the test bed.

 

Sadly, it all went out of the window when it was supercharged.

 

There was a happy ending, as the supercharged engine won Indianapolis.

[luismx123]

 

I flowbench tested this a couple of weeks ago, showed a decent gain in flow and is designed to fit under a K&N cone filter. Available for the 1-1/2" and 1-3/4" SU.

 

Different length ram pipes can be used to tune the inlet length and are used to alter the torque spread of the engine. Tuned lengths can have quite a dramatic effect when done correctly.

Phil.

 

 

Who's is that Phil?   There's a lot going on the face of it; there's gains to be made there!

 

guy called dave was selling them a week or two ago

[timmy850]

For sale topic is here:

http://www.theminifo...52-stub-stacks/

[AKat]

On anything with a Siamese ported head stub stacks work well, however it is hard to take advantage of any wave tuning that can be had from longer ram tubes. 

The other factor is the engine speed where you want to tune it for (there is no "One Size Fits All" solution... hence why some motorbikes run variable length systems)

 

The formula that was used by manufacturers for determining the "ultimate" induction tract length many years was;

L = [(K x C) / N]

L = obviously length
K = a mathematical constant.. used to be 72 but in later years other manufacturers started using other numbers like 87 and 90... for an A series stick to 72
C = speed of pulse (determined by air density - mostly by temperature on an NA engine.. work with 1,100 for 25 degrees C at sea level)
N = Engine speed

 

So we're talking about a 1330 for fast road application... I'm going to say it will spend its life around the 3000-5000 rpm range?  So I'll work it out on the average

72 x 1,100 =  79,200

79,200 / 4,000rpm = 19.8" from the edge of the ram tube to the back of the valve down the centreline.

Obviously space starts to become a limitation in the real world (and especially on minis! )  but you can sort of see why guys with webers want to aim for those 8" manifolds where they can. 

 

So if you don't mind cutting holes in your fire wall .......

Otherwise, you won't be disappointed with a stub stack