13 replies to this topic

[rozzer1275]

1380, 286cam, 1.5 rockers, 37x31 head, su hif44

Anyone know the max power posible out of an a series engine fitted with 1 hif44 su carb, as I now think it is the limiting factor in my engine, i am getting a respectable 102hp (on apparently conservitive rolling road).
my engine is strong, but i suspect a change of carb (to twins/weber/or efi throtle bodys) will release some more horses, what are your thoughts people?

[jaydee]

A single hif44 can handle it, but twin hs4 will be far better for engines with little more than 100bhp. I dont htink u'll have a sensible power increase with them, for sure u'll have more torque and more response.

[beaubrad]

why not get a set of twin HIF44 from a mg??

Edited by beaubrad, 20 February 2009 - 01:43 PM.

[ianpettifer]

Whats your engine spec as im looking to break the 100bhp barrier?

thanks

[rozzer1275]

Whats your engine spec as im looking to break the 100bhp barrier?

thanks

1380 budget engine (quite low comp)
286 cam x drilled
1.5 roller rockers
37x31 valve head
hif44 carb, with short ram pipe
mega jolt ecu ignition
ally inlet manifold
3 into 1 exhaust + RC40 twin box system

[rozzer1275]

thanks for replys
just thought the carb maybe capping the power.
I do have a couple of mg SUs in the garage but they look a bit big

[phil hill]

Last thing first, so far as I know MG's and specifically MGB's didn't have twin HIF44's with the exception of the MGB V8. The 1800cc MGB's had twin HIF4's for sure as I've got two sets on my bench at home !!

The single vs twins debate is one that runs and runs. I've had an 1380 with HS4 twins, it was fine and they didn't go "off tune" all the time like people tell you and are not more unreliable etc. What they are is more complicated and more difficult to get set up correctly in the first place as well as more costly and likely to be hampered by *yellow human water*-poor designed manifolds and filters unless you choose very carefully.

The advantage of the big single HIF44 is that there is only one of them to have to set up, one needle, one spring etc and more than likely you've already got one fitted to the car with a pretty good manifold already attached. Filtration is up to you but again you only need one filter not two........ In pure air flow terms the HIF44 is excelent and quite capable of providing all the air your engine needs with maybe the exception of a couple of HP at the very upper RPM range, and there are things you can do with a file, a saw and some loctite to further improve the carb if you are so inclined. Try reading Vizzard or the SpeedPro book on SU's for details.

So do you want the hassle, complexity and additonal capital outlay of some twin SU's for a handful of HP at max. rpm or are you hell-bent on the classic "cooper S look" ?? If the answer to any of the above is no then don't bother with the twins.

Webbers ?? I've no personal experience so can't comment.

Injection ?? Whole different ball game but in general the OEM systems fitted by Rover won't be ideally suited to you current engine. There are aftermarket systems which could be used, but they are costly.

All IMHO of course !!

Phil.

[ianpettifer]

cool

I have a 1275 with a stage 1 kit

hoping to get 1.5 titan full roller 1.5 ratio rockers
stage3 head
hi44 carb

how much bhp dya reckon that make?

cheers

[maph2]

Injection ?? Whole different ball game but in general the OEM systems fitted by Rover won't be ideally suited to you current engine. There are aftermarket systems which could be used, but they are costly.

all good stuff from phil. regarding injection, you will be able to liberate quite a few more ponies by going to canems fuel injection. not cheap but will liberate the power loss due to the 2 cyclinders that always run weak in a siamesed engine like the a series. i think running the megajolt is far more advantageous than upgrading the hif44

editr: i don't work for canems by the way

Edited by maph2, 20 February 2009 - 02:37 PM.

[phil hill]

cool

I have a 1275 with a stage 1 kit

hoping to get 1.5 titan full roller 1.5 ratio rockers
stage3 head
hi44 carb

how much bhp dya reckon that make?

cheers

Sorry to hi-jack, but : Probably about 10 more than you've got now.

1.5 ratio rockers are not really a subsitute for a performance cam, but they are a whole lot easier to fit !! Assuming you mean 100hp at the crank then you will need a properly built engine with a cam such as the 286 Rozzer's engine has.

Can I ask why full Rollers ?? They are very expensive and not really necessary unless on full race applications, and even then it's dubious ??

Phil.

[rozzer1275]

Thanks again all

as to phill's comments, i have had some experiance on webers on another car some years ago, they sound great and give little restriction, but a found them a pain as the setup cost on all 4 chokes.
I have also played with filling down butterfly shafts etc on an spi throttle, but found all that a lot of work for little gain. (if i get the time i may do it)

I do prefer single carb its just one carb to go wrong.

the carb has been fine, as said the engine is very strong, i get a bit peed with choke and not idling with the lights on etc.

as to maph's comments, yes mega jolt has been great, transformed the car, I beleive that carbs are better at fueling than dizzs are at ignition.

I have found myself thinking about injection, my head says single point for simplicity, but my heart says go for custom twin injector. maybe with mega squirt or that canems thanks for the name drop.

ian as said cam will make a difference, hard to say on your engine what is it standard 50hp, may go between 60 and 80hp make sure it has new, plugs, leads, points, oil and filter, carb needle, air filter, set up rocker gaps, and all tuned up on the rollers. exhaust manifold and system will help with those mods. may have lost hp on the old engine also.

Edited by rozzer1275, 20 February 2009 - 06:11 PM.

[m1n1]

my twin hif6 came from a 1978 2.2 princess. fitted on a maniflow steel manifold, bodging my own linkages out of a hs4 kit.

they worked quite well.. better idle.. bit more power.. looked nice to!


for the mo im back on a single hif44.. works well and keep ahead of most things.

[level7]

1380, 286cam, 1.5 rockers, 37x31 head, su hif44

Anyone know the max power posible out of an a series engine fitted with 1 hif44 su carb, as I now think it is the limiting factor in my engine, i am getting a respectable 102hp (on apparently conservitive rolling road).
my engine is strong, but i suspect a change of carb (to twins/weber/or efi throtle bodys) will release some more horses, what are your thoughts people?

A guy here in NZ managed 107 and 104 bhp at the wheels on 2 different dynos from a single hif44 on a 1360 in his daily driver van

[philc]

1380, 286cam, 1.5 rockers, 37x31 head, su hif44

Anyone know the max power posible out of an a series engine fitted with 1 hif44 su carb, as I now think it is the limiting factor in my engine, i am getting a respectable 102hp (on apparently conservitive rolling road).
my engine is strong, but i suspect a change of carb (to twins/weber/or efi throtle bodys) will release some more horses, what are your thoughts people?

imo opinion i ddon't think you will get much more than what you are getting, you may get an extra 5bhp if you changed to a wber which in turn will give you more torque over anything else, I can't get anymore than 107 unless i start blueprinting the engine a little, change piston rings maybe a little more porting ect,