36 replies to this topic

[Mini Manannán]

 

 

What do you think of this one:
 http://www.ebay.co.u...=STRK:MEBIDX:IT

Would be interested in peoples opinions on this too, as I would like to fit a stub stack to my HIF44.

The top edge is very thin and is almost a sharp edge rather than a full radius. I'd certainly be interested to flowbench test it and see how it compares to others.
I'll happily do this for free if anybody has one they want to send.

Phil.

 

 

Phil, I have a sub stack I designed to fit into a small space and had 3D printed  I wonder if you'd be interested in flowing mine?

[Turbo Phil]

Yes, no problem. If you're happy to cover the return postage I'm happy to test it for free.

Phil.

[Trissy B]

So, I ended up buying the stub stack off ebay (http://www.ebay.co.u...=STRK:MEBIDX:IT). Its a nice item, well engineered and fits well on the plate. BUT, it doesn'tt fit under the normal K&N cone filter like I have. Took about 2 hours playing around and speaking to the seller to get it to fit. Had to grind off both bottom corners and fillet these off. Also had to remove the inner and outer material from the bottom of the actual filter element. Quite a lot of effort but the end result is a good fit, just needs a bit of filing.

 

Turbo Phil kindly has flowed this at +5% over no stub stack, so it seems to work well. I'm sure Turbo Phil can give the details. My original K&N stub stack (a very much inferior item in terms of quality! and about the same price), was flowed at +3.5%, so not a million miles off.

 

modified ebay stub stack

 

My original K&N stub stack

[Readers14]

Very good.
Comparing the two stub stacks, it looks like the eBay item has a deeper, smoother radius into the inlet of the carb.
Its a shame it doesn't fit under a K&N cone filter without modifying it.

When say you had to remove the inner & outer material from the filter, do mean the rubber seal that's bonded to the cotton gauze?

[Turbo Phil]

Thanks to Trissy B for kindly donating the stub stacks for testing.
If anybody else has any they want testing let me know.

First up is the K&N stub stack. Thankfully this flows better than it looks. It's quite a rough casting and certainly isn't impressive to look at.
This showed a gain of 3.5% over a bare HIF44 carb.


Next is the pipercross ram pipe. This could be better made as the entry into the carb on the carb body is 46.5mm, but the rampipe is only 42.5mm so overhangs into the entry somewhat. Despite this is shows a decent gain with a 4.0% improvement over a bare HIF44 carb.


Next is the alloy Bellmouth from an eBay supplier. This is very nicely made and the fit is excellent. This showed a 5% improvement in flow over a bare HIF44.
In the picture below I added some putty to the top edge to see if forming a better radius at that point improved flow. There was a very minor gain.

[AlexMozza]

What sort of effect would the filters have on the stub stacks.
Reason I'm asking is I have two HS4s and I'm looking at fitting stub stacks. The MED kit with ITG filters ect.
Do the filters effect the air flow much?

[racingbob]

Have you ever flowed a med one

[Turbo Phil]

Have you ever flowed a med one

The ITG type ? No. Do you have one ?

Phil.

[Trissy B]

Very good.
Comparing the two stub stacks, it looks like the eBay item has a deeper, smoother radius into the inlet of the carb.
Its a shame it doesn't fit under a K&N cone filter without modifying it.

When say you had to remove the inner & outer material from the filter, do mean the rubber seal that's bonded to the cotton gauze?

 

Yup, the rubber seal on the inside came away very easily with a sharp stanley knife. The outer seal, not as easy. Basically kept taking it back with the grinder but ended up needing to take a lot off, which was quite difficult with the thing flapping around! Thus the rather messy job. Not pretty, but seems to quite solidly seal.

 

Edited by Trissy B, 04 June 2017 - 06:51 PM.

[racingbob]

Have you ever flowed a med one

The ITG type ? No. Do you have one ? Only on the car not spare

Phil.

[blacktulip]

Loving this thread, excellent work and hats off to Phil for spending time on these for free.

[Turbo Phil]

Loving this thread, excellent work and hats off to Phil for spending time on these for free.

No worries. Once I have the bench set up it only takes a few minutes to fit and test each one.

Phil.

[nicklouse]

 

Loving this thread, excellent work and hats off to Phil for spending time on these for free.

No worries. Once I have the bench set up it only takes a few minutes to fit and test each one.

Phil.

 

Phil when you say bare i guess you main as above but without anything attached? just curious if you had tested with the OE elbow fitted and how that effected things.

[Turbo Phil]

Yes figures quoted are the increase in flow over that of a plain carb with no elbow or radiused entry.
Yes it would be interesting to test with the standard factory elbow, do you happen to have one ?

Phil.

[Turbo Phil]

What sort of effect would the filters have on the stub stacks.
Reason I'm asking is I have two HS4s and I'm looking at fitting stub stacks. The MED kit with ITG filters ect.
Do the filters effect the air flow much?

The filters are always going to cause some restriction, however minor. I doubt if it will retract from the actual effect of the stub stack though.
As with everything though what you think should work doesn't always, and what you think won't work sometimes does. It makes using a flowbench an interesting experience.

Phil.