stock fuel pump and HIF 44 limits, odd problems on dyno ( NA sorry)
Turbo Mini Forums

Hi,

An engine i build just had a RR session ( i was not there as i had to watch patients...)

the guy who normally tends to do good work had huge trouble the get the fueling anywhere near right and as a result started blaming all kinds of stuff. head work, engine build..

As i did both the head work and the build i am truely annoyed and this is going to be a matter of principle and reputation..


the spec is as follows:
NA
1310cc
RE13 cam timed at 105 degrees (DTI) w./ CR 10.5
forged minispares 1.5 rockers ( which tend to be 1.5+ it seems)

Head, basicly a vizard method head with 35.7mm intakes (20/45/70 seats with a 1.5mm with) 29 ex with a 0.60 mm seat valves back cut to contact face at 30 degrees. Ports are mostly changed but not enlarged to more than a clean up and bias changes. All other heads i have done tend to be rather good performers ( both SB & BB (NA)

short block is ye basic fast road build with pistons set to zero deck height. rings gapped. turns round easily at about 9NM passive. no large blow by problems

Carb is a HIF44 in stock trim ( with the bi metal and stock jets, float valve) using a CST donut and ITG filter.

it still uses the mechanical pump.

RR output was about 85 BHP but it appearently runs crap and the mix is still off and it should make at least near 15 more bananas

as a lot of you run HIF carbs with high BHP engines. what are you mods to the HIF44 ?? ( other than the ones needed for forced induction).

IMHO this is first and foremost a fuel/ AF mix problem.

the ignition is is a stock metro leccy dizzy and thus in all probability not good for the engine.


i wil be getting the AF and RR read-outs shortly


suggestions very welcome

cheers.

Edited by Sir Yun on 8th Feb, 2008.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

I've seen std unmodified Hif44s deliver over 100hp on a Norwegian "strict" dyno. Shouldn't be a problem.

Unfortunately, you cannot compare booster power figures to n/a power figures using the same carburettor.

Its just soooo different.

A carb that may struggle to make 50bhp n/a, could well make 150bhp when blown.


Is your tuner trying to tune with a standard needle, or did he try a selection of SU needles to get the fuelling right ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

well i would say i dont know the spec of the 13 cam, but depending on the rollers about 90 bhp at the flywheel would be about right for that spec.

but i would guess at he needs to trim the needle to suit.

the elecy dizzy will be fine as well

always looking for them bigger bunches of bannanas

see if the choke seals are leaking ?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

is the mechanical pump in good condition? surely this must be around the limit for one?

carb, no problems, but pump i would definately be suspect of.

thanks for the input blokes :)

I thought about it some more.

I suspect the pump as well as the float bowl valve thingie. too rich at idle. after 4K the metering was out of the window and did not respond at all to modifications or swapping of needles.

maybe it needs an extra spring as well.

after inquiring the dizzy is way off to what is normaly needed for this cam and like setups.


the good news 80 isch bannanas at 4 and a bit K rpm with crap fueling from 3.5 and up to boot with a cam with a powerband from 3.5k to 7k. isch..


there be bannananas in them hills somewhere.


EDIT:


found the problem(ss).
Alternator died (and in retrospect was near death a while).
One tappet had gone off.

Rebuild the carb


Needle profile stupid ..Jet was too far (meaning as far as it wil physicly go) down the bridge making all fueling crap (as fuel needs to be sucked up 18mm up a big hole and then take a 90 degree turn..then atomise in a controlled manner..guess what, it doesn't). i'll mention that to the dyno guy (he was blaming my headwork)


changed the needle to a stock BDL on a stock mg bell and piston assembly .. runs better and have adjustmet option left. Only ball park fuel wise, but better across the board for drivability.

drilled the float jet to 2.5mm.
so the float chamber will stay flooded at WOT.

easy peasy ..only took me a month

Edited by Sir Yun on 31st Mar, 2008.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/