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I need your help deciding which fuel system to use in my Fiat 500/1108 fire engine project, I built the car with a 32/32 weber progressive twin choke rather that the fuel injection that came with it as it was one less thing to work out at the time and I thought I would concentrate on getting the engine fitted and running. It was only ever meant to be a temporary solution and I am now trying to decide which way to go. I am planning some head and valve work over the winter along with a proper custom made header/tailpipe so want to get the inlet side sorted as well.  Do I (A) put the fuel injection back on to the car, its an MPI system and there are a few bits you can do to the throttle body to get it to flow better, the ecu is re-programmable so I can map it to suite, apparently with the right mapping its good for over 100bhp at wheels. or do I (B) Fit the set of 34mm bike carbs that I have sitting on my shelf, fab up a manifold and stick with the dissy/electronic ignition. I have no experience of these but my local rolling road seems to think that they can jet them to suite. or (C) the expensive route, buy a set of DOCE 40's and fabricate a manifold or (D) the sell the kids and get a divorce route, throttle bodies and a programmable ecu. or (E) leave as is Any views would be much appreciated |
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what wrong with it at the moment, if its working and its creating a goodly amount of ponys then stick with it
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Bike Carbs.
*n
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Top grammar tips!
Bought = purchased. Brought = relocated
Lose = misplace/opposite of win. Loose = your mum
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I very much doubt you'd get 100bhp from an 1100cc FIRE engine.
I've seen engines kicking out 75bhp, but 100bhp needs a turbo.
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Prius T-Spirit, Alfa 156 Sportwagon, Alfa 75 TSpark Veloce, Mazda MX-5 1.8iS
Honda VFR750FT, Ducati 750SS, BMW R100RT, Hongdou GY200
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I very much doubt you'd get 100bhp from an 1100cc FIRE engine. They said I'd never get a fire engine to fit into a 500 either but..... I am only going on what I am told by the Fire engine experts, 100bhp is perhaps a little ambitious but there is no point in setting your targets too low. The Multipoint system on the 1108 is the same as the 1242 and is 'apparantly' capable of fueling over 100bhp The article in Retro Cars (I know most of what they print is rubbish) on tuning the fire engine had Wolf Direct Racing quoting around 123bhp at 7800rpm for a full race 1242cc normally aspirated engine running throttle bodies, and 95 bhp on a 1242 with what the call a stage 3 tune – gasflowed head, standard valves, raised compression, fast road cam, ballanced and lightend bottom end, freeflow manifold, MPI system. I know my engine is 134cc smaller, but I do think that getting over 85 - 90 bhp mark should be reasonably easy, the spec I am looking at is: Gas flowed head, 1mm oversize valves with 3 angle cut, light-weight valve train, race cam, increased CR, fully lightened and ballanced bottom end, modified MPI system or bike carbs or DCOE 40's (see thread title) Custom made race exhaust (no cat needed on 1974 car). Only time will tell.... Anybody got any views on the carbs/MPI question |
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slater
Club Retro Rides Member
Posts: 6,390
Club RR Member Number: 78
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Bike carbs.
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Oct 10, 2006 10:40:03 GMT
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Thanks slater, why do you think bike carbs? I bought a set to fit but having thought about it i'm not sure they will be better than the MPI system or webers, as I understand it they work in the same way as SU's so don't have a pump for that initial hit of fuel like webers do. I don't really know much about fuel injection either but my Fire engine expert thinks its the best way to go  |
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Oct 10, 2006 10:42:41 GMT
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Bike carbs are the new hotness for small engines,.. I'm sure one of the engineering types will come up with a valid reason,..  I think sounding cool is good enough  ... |
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skinny
Part of things
Posts: 22
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Oct 10, 2006 10:52:21 GMT
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Bike carbs are old hat.... Bike tb's like the ones I have for sale are the nu 'thang  |
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Oct 10, 2006 10:59:40 GMT
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One carb per cylinder. They flow more than an 'equivelant' weber setup. Once tuned, they shouldn't need constant fettling. Constant velocity design means that there are no fuelling flat-spots through the rev range. They're cheap. Bogg brothers can get you a fannymould sorted. They're basically the zenith of carb design. It's best to look at power outputs when taking them into consideration - if the bike they're off can flow 150bhp from a litre stock and 180 modified then they should be good for engines up to 2 litres and similar power. Remember that the carb does not see revs or capacity - only airflow. A '42mm' bike carb is 42mm straight through. A '42' Weber...Isn't And, saving the best for last, they can handle pressure...So you can bolt a blower on the side *n |
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Top grammar tips!
Bought = purchased. Brought = relocated
Lose = misplace/opposite of win. Loose = your mum
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Oct 10, 2006 11:01:34 GMT
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Bike carbs are old hat.... Bike tb's like the ones I have for sale are the nu 'thang It really depends how complex you want to be? With carbs it should literally be a case of four wires, connect, start it up then get them tuned for the engine with a rolling road session. [Edit: and they should be almost as efficient as an EFi setup due to the nature of their design. You may not be able to see the ultimate flow and power characteristics that ITBs would provide but... ...It's an 1108 engine! Not a 2.0 16v that you want 250bhp plus out of... ] *n |
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Last Edit: Oct 10, 2006 11:03:58 GMT by penski
Top grammar tips!
Bought = purchased. Brought = relocated
Lose = misplace/opposite of win. Loose = your mum
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Seth
South East
MorrisOxford TriumphMirald HillmanMinx BorgwardIsabellaCombi
Posts: 15,538
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Oct 10, 2006 11:03:51 GMT
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Hmm. Out of those choices either the bike carbs or the DCOE's. No engineering reason at all. I just think either of those would look the best  ;D Hope this doesn't mean the 500 is off the road for any length of time  Coming to the Ace tonight? |
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Follow your dreams or you might as well be a vegetable. |
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skinny
Part of things
Posts: 22
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Oct 10, 2006 11:18:30 GMT
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Ok ok... so... carbs if you want to keep it 'reasonably' sensible and tb's if you're a bit unhinged (like myself) and for info... I wasn't aiming for 250bhp from a 2ltr. 175bhp is achievable without too many mods. We're only talking a 25bhp over standard on a C20XE but, I'm digressing further away from the subject in hand Who can refuse the fun of Megasquirt ECU's? They're great! Especially my old which was live mappable and could be done by an idiot thanks to the superb software. |
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Oct 10, 2006 11:22:34 GMT
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whats so good about bike carbs?  |
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Oct 10, 2006 11:25:12 GMT
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Hope this doesn't mean the 500 is off the road for any length of time Coming to the Ace tonight? No the car is still up and running, I'm just planning the jobs I can do in my little workshop over those cold winter nights (no garage). I have a spare engine to used as a mock-up/jig for fabricating the inlet and exhaust manifolds ect We will be at the Ace tonight, see you there. |
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Mr K
Posted a lot
Posts: 2,993
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Oct 10, 2006 11:59:50 GMT
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the spi is more of a emmissions thing than a performance item! bin it!
the mpi uses a single tb and 4 injectors, however bike itbs have the obvious of their own equal supply of air due to bassically being 4 injectors, and 4 tbs...
the mpi system is easy to do as the bits are all out there and bolt together, the loom for the ecu is seperate from the rest of the loom on the fiat, and as you say, its mapable.
one thing to look at with bike carbs is that although they are cheap enough to buy, the needles cost a bomb for some and certainly are not as easy to set up as a weber 40, or SU.
for mine (1240 fire twink) i am looking at running twin SUs to start with, this is because i can set them up in the garage, the manifold is simple, and the carbs are cheap... or maybe twin 40s, but the costs would be higher, and i don't want to waste money on a temp fix.
for the spark (no disi on a 16v fire) i am going to use somthing like mega spark. this will later all be binned in favor of bike ITBs and a supercharger!
i would say twin 40s, or bike itbs personally... but at the end of the day how much do you have to spend? (the cost of megasquirt, and some bike tbs is porbably simular to that of some twin 40s, and for both you can easily fab your own manifold - although any fabricators / bogg bros could do it for you if your lazy or it ends up hugely complex!
keeps us updated on how you get on!
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slater
Club Retro Rides Member
Posts: 6,390
Club RR Member Number: 78
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Oct 10, 2006 12:13:33 GMT
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Bike carbs are bloody easy to fit, cheap and work pretty well.
Injection is alot more complicated to fit is a damn site more expensive but isnt a huge amount better.
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Oct 10, 2006 12:17:58 GMT
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I'm not a fan of injection, i like to be able to understand whats going on and i understand carbs not ecus etc
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Oct 10, 2006 13:03:28 GMT
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I'm debating at the moment what to do on the Datto,.. It'll either be bike carbs, or R5 Turbo set up... Still want to go EFI,.. just to make use of the Throttle bodies I've got... |
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skinny
Part of things
Posts: 22
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Oct 10, 2006 13:10:17 GMT
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With the new Megasquirt gear so easy to use and readily available I'd say go for it! I got my V3 ECU from www.mtechperformance.co.uk (I think that's right!) It could govern the spark and the fuelling. Other models could do just the fuelling or just the spark. It's pretty much up to you how far into it you want to go. Either way, with tbs and carbs, to have them professionally set up is costly. You are looking at around £450+ (+vat) for a day on the rollers. That is the only way to get them to run correctly, effeciently and be at their peak performance. |
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Last Edit: Oct 10, 2006 13:15:19 GMT by skinny
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...
;D
Coming to the Ace tonight?
