12 replies to this topic

[Inno]

I am rebuilding Carburator SPI engine from 1993 and plan to increase performance a bit - not more than 85-90HP.

 

Beside other elements I plan to change (pistons +20 or +40, new camshaft, 35.7 intake valves, bore head a bit, light flywheel, stage 1 intake and exhaust) my concern is Hif38 that I have.

 

Would it be possible to keep HIf38 and with all mentioned achieve those +/-90HP?

 

And is there anything I can do with Hif 38 to improve performance - is there any Hif 38 upgrade available?

 

I know that Hif 44 would help but I am trying to keep it up to the budget and I would like to try to do it with 38.

 

This will be the engine for Innochenti 1300 Cooper that I found recently (with 1000 Cooper engine inside?!?) Body and engine are in terrible shape, but the car is complete with all parts including 6 gauges dashboard and 7.5 front discs. I am starting full restoration.... . 

 

 

Thanks in advance..

[Cooperman]

An HIF38 is far too small for a 1293. It is fine on a 998, but it is the same effective diameter as an HS4 and for best power on a 1293 twin HS34's are usual. You might manage to get around 65 bhp with it, but probably no more than that

An HIF44 works OK.

The cross sectional area of an HIF38 is 1134 sq.mm, whilst the HIF44 is 1521 sq.mm., so quite a big difference.

The original 1275cc Innocenti Cooper 1300 had twin HS2 carbs as standard and gave a nominal 71 bhp. These have a combined cross sectional area of 1584 sq.mm.

If you do stick with the HIF38, you should have small inlet valves to get the best intake speed for the mixture. Big valves with a small carb will give a very slow mixture inlet velocity, further reducing power.

[Retroman]

 

Would it be possible to keep HIf38 and with all mentioned achieve those +/-90HP?

 

And is there anything I can do with Hif 38 to improve performance - is there any Hif 38 upgrade available?

 

I know that Hif 44 would help but I am trying to keep it up to the budget and I would like to try to do it with 38.

 

 

 

 

 

 

If I Vizard the HIF 38 there are big improvements to be made, including a stubstack.

 

1107cc  80 horses and a really nice flat torque over 60lb 3 -6k peaking at 70 lb with a road cam 33 29 valves.

 

It made a really nice tractable drivable Mini, the lad loves it.

 

The alterations allow the 38 to flow about 30% more and being a smaller the gas speeds are higher which lifts the torque

 

 

PM me if you want it Vizarding, its cheap power

 

Ultimately an engine is just an air pump and you can make it more efficient by less restrictions [within reason]

[nicklouse]

i would swap it out for a hif44

[Inno]

An HIF38 is far too small for a 1293. It is fine on a 998, but it is the same effective diameter as an HS4 and for best power on a 1293 twin HS34's are usual. You might manage to get around 65 bhp with it, but probably no more than that

An HIF44 works OK.

The cross sectional area of an HIF38 is 1134 sq.mm, whilst the HIF44 is 1521 sq.mm., so quite a big difference.

The original 1275cc Innocenti Cooper 1300 had twin HS2 carbs as standard and gave a nominal 71 bhp. These have a combined cross sectional area of 1584 sq.mm.

If you do stick with the HIF38, you should have small inlet valves to get the best intake speed for the mixture. Big valves with a small carb will give a very slow mixture inlet velocity, further reducing power.

Thanks a lot....I heard Hif 44 is good for turbo way above 150 or even 200HP so I thought it might fit up to 90HP. Good point regarding valves.

[Inno]

i would swap it out for a hif44

......not so easy to find it for reasonable amount .......

[Inno]

 

 

Would it be possible to keep HIf38 and with all mentioned achieve those +/-90HP?

 

And is there anything I can do with Hif 38 to improve performance - is there any Hif 38 upgrade available?

 

I know that Hif 44 would help but I am trying to keep it up to the budget and I would like to try to do it with 38.

 

 

 

 

 

 

If I Vizard the HIF 38 there are big improvements to be made, including a stubstack.

 

1107cc  80 horses and a really nice flat torque over 60lb 3 -6k peaking at 70 lb with a road cam 33 29 valves.

 

It made a really nice tractable drivable Mini, the lad loves it.

 

The alterations allow the 38 to flow about 30% more and being a smaller the gas speeds are higher which lifts the torque

 

 

PM me if you want it Vizarding, its cheap power

 

Ultimately an engine is just an air pump and you can make it more efficient by less restrictions [within reason]

 

...thanks...this is what I had in mind when asked for a help...heard about some modifications have been done....have 2 Hif38 so can play a bit.....sending PM

[Pigeonto]

It will be interesting if you do take this to a conclusion using the 38.

I've always reckoned 100 hp is possible with a worked 38

You're using 35.6mm valves. Only one cylinder is drawing at a time. Valve stem/guide pretty much equals throttle spindle by way of a restriction The carb is 38mm...........

Make sure the dashpot spring is light enough to allow the piston to reach the top.

Blimey, talk about cat amongst the pigeons !!

[carbon]

How much power can you get from a normally aspirated A-Series using a single 1.5 inch SU? 108 bhp

 

This was from a Howley 1430. See David Vizard's Tuning BL's A-Series Engine (Fig 7.3, page 77, 1st edition).

 

And for comparison the 1.75 inch HS6 gave an extra 6 bhp = 114bhp on the same motor, both measured at flywheel using engine dyno. Does not say if the carbs were 'vizarded'.

 

Also I would advise caution on radiusing the SU piston leading edge, as in my experience (with twin HS2) this can over-richen the mixture under acceleration to the point where you get misfiring.

[Retroman]

I always radius the leading edge always have, always will

 

I have never had any misfiring due to too rich and no customer has said its an issue either,

If the engine is drawing the air its just a case of getting the needle(s) and mixture right on the rolling road

 

It makes no sense to me to expect air to flow round any sharp edged object, manifold and head dividers included

 

and the large radius piston edge technique works even on HS2's 

 

The last HS2 I did was for Simon Boulter 750 MC racer and he gained 22% torque, won 2 races and got a mention in Autosport

His formula have to use the Reliant 848cc engine and a single HS4 carb.

This is from his email from him before the Penbury races:

 

"Had the car on the rollers this week the results were very good. It gave 55bhp and 55 lbft torque, this was up from 45 lbft before."

 

This compares well to the output of a standard 998 Cooper, in a car that weighs 303kg

 

If anyone wants his testimonials PM me

 

Interestingly I have 2 pairs of Longman 1 1/2" SU's --

 

H4's bodies are bored to 41mm and welded /machined the leading side of the bridge, pistons not radiused

 

HS4's bodies bored to 38mm and welded / machined as per the H4's, pistons have a big radius just the way I do them

[Inno]

After some research I decided I will go for Hif44.

 

Question is what would be recommended HIF 44 spring and needle for 1290ccm, and targeted 95HP?   - to start with...

[gazza82]

HIF6/44 Series

Engine Size      Needle Std.  Needle Rich  Needle Lean  Spring Type

1300 Standard BFY             -                   BER                Red

1300 Turbo ‡   -                  BDD              -                      Yellow

1300 Metro ‡    BEJ            BDL               BER                Red

 

 

Sorry this was a cool table when I copied it!

Edited by gazza82, 08 November 2018 - 11:20 AM.

[Inno]

HIF6/44 Series

Engine Size      Needle Std.  Needle Rich  Needle Lean  Spring Type

1300 Standard BFY             -                   BER                Red

1300 Turbo ‡   -                  BDD              -                      Yellow

1300 Metro ‡    BEJ            BDL               BER                Red

 

 

Sorry this was a cool table when I copied it!

thanks...I got the idea...just where to put mine....1300...a bit stronger than standard...but far from Turbo...