carbs or throttle bodies.

[therealnovaboy]

ive heard this mentioned before on here and ive heard people saying that carbs are better than throttle bodies on an 8v. how can this be true. the other thing people liked carbs better because they are cheaper again i cannot see how this can be true, surely once you set throttle bodies up thats it but carbs you have the expence of re tuning. i recon you could get throttle bodies and a ecu for the price of twin carbs. am i being stupid or is ther something im not getting.

[Adam]

Carbs never need re-tuning once you have them setup, unless you change the way the engine breathes.

Twin carbs can be had for about ?300 with everything you need.
Then just need setting up on a rolling road, maybe ?200 ish.

TBs are ?400 for the bodies alone, ?300 for cheap management, plus you'll need inlet manifold etc. And ?500 for mapping.

[peester]

try a spot of mix n match - if or when i get carbs; im gonna megasquirt them (!) so programmable management on the cheaper to buy option - possibly as good as results..

[Stuart]

the way that TB's are setup mean that if you buy 40mm TB's thats the size of the intake, whereas 40mm carbs are usually choked down to 30-34mm so the gas speed is kept inline with what the engine is happy with (in 8v applications). If you fit 40mm TB's to an 8V engine then it will make peak power very very high up the rev range and possibly have poor low end driveability due to the massive intake size and a possible drop of gas speed to cause the fuel to fall out of the air..

if you have your carbs built and setup right by a GOOD tuner then they wont need touching ever.... the "they go out of tune" myth has been round for years propgated by people that go for a ?5 tune up at a RR day, resulting in pish poor results and tune drifting with bent spindles etc.

[maccas]

do you mean megajolt? because with carbs you don't have any electronic fuel injection to control, megasquirt does both the fuel and the ignition whereas megajolt does just the ignition which is all you would need on carbs

[Stuart]

MJ and Ms cost nearly the same.... so for future proofing, plus a BETTER spark controller there is no harm using megasquirt.

[therealnovaboy]

what about motor bike throttle bodies you can get them for the guts of 80 quid and a megasquirt ecu for about 200. a manifold is not exactly hard to make a bit of 6 mill plate with holes drilled in it and 4 pipes welded on would be suffice.

how are you going to megasquirt carbs do you not mean megajolt them?

but are carbs better than tbs on a 8v.

[therealnovaboy]

the way that TB's are setup mean that if you buy 40mm TB's thats the size of the intake, whereas 40mm carbs are usually choked down to 30-34mm so the gas speed is kept inline with what the engine is happy with (in 8v applications). If you fit 40mm TB's to an 8V engine then it will make peak power very very high up the rev range and possibly have poor low end driveability due to the massive intake size and a possible drop of gas speed to cause the fuel to fall out of the air..

if you have your carbs built and setup right by a GOOD tuner then they wont need touching ever.... the "they go out of tune" myth has been round for years propgated by people that go for a ?5 tune up at a RR day, resulting in pish poor results and tune drifting with bent spindles etc.

so if you had throttle bodies that wernt 40mm and were say 34mm they are suerly better than carbs as they can be tuned more acuratley, easier.

[Stuart]

bike TB's go down as small as about 38mm... unless i can be proved wrong lol. so the orafice is still too big for even hardcore 1.6 8v tuning.

MS can be used to control the IGN on its own, and has better software + hardware setup options than MJ

[Stuart]

34mm assuming thats the sized choke you needed.... if you need smaller then you might still be fecked.

Of course you "could" make slieves that are effectively chokes for the TB's but then your not gaining much over carbs on the 8v setup.

[peester]

its possibile to run carbs off any programable engine management i thought...? DTA/MBE/the diamond, jewellery -sounding one, can't rememeber now..

[therealnovaboy]

34mm assuming thats the sized choke you needed.... if you need smaller then you might still be fecked.

Of course you "could" make slieves that are effectively chokes for the TB's but then your not gaining much over carbs on the 8v setup.

but then again carburators can varey with the weather, throttle bodies take into acount air temp which would have an effect on the carburators. no?

[maccas]

my mistake..... i suppose it would make sense to buy megasquirt or similar as a future investment wouldn't it, just out of interest, if you can run carbs on just the ignition side of things of such a programmable setup, can you run carbs on just the ignition part of a standard ecu? can this be done? obviously it won't be very adjustable, but would it run, sorry for hijacking the thread a bit

[therealnovaboy]

its possibile to run carbs off any programable engine management i thought...? DTA/MBE/the diamond, jewellery -sounding one, can't rememeber now..

you can if they can map for ignition , as most would. decent ecus cost about 300 pound, you can get a mega jolt for 80 quid.

[therealnovaboy]

my mistake..... i suppose it would make sense to buy megasquirt or similar as a future investment wouldn't it, just out of interest, if you can run carbs on just the ignition side of things of such a programmable setup, can you run carbs on just the ignition part of a standard ecu? can this be done? obviously it won't be very adjustable, but would it run, sorry for hijacking the thread a bit

yes but the ignition would be mapped for the standard set up and not the carbs, your timing would not be very suitable for this. it would work, youd also have the limiter as well unlike a distributer setup.

[Stuart]

the weather has marginal effects that weve seen, ok a cool summers night/morning is awesome for performance, but then again the same is true for a TB'd car...

if you talking balls out 16V setup etc then TB's all the way, Chris T managed to get about 10bhp and a more driveable car by converting from 45mm carbs to TB's but then his engine is a well specced beastie.

TB's are the best option for a 16v/high airflow etc engine. but for small 8v ones then carbs are the "best" unless you fit MPI and map that properly.

Im a huge fan of TB's and the are the "best" BUT from people trying etc its just not the right way to do it for the cash on 8v engines such as ours due to the TB sizes stopping at 40mm and not going smaller. 35mm TB's would be fantastic and would sell well imho

[Adam]

Or, forget the carb/tb's idea.
And just fit MS to a std 1600 8v engine, std inlet etc.
150bhp

[therealnovaboy]

is that why some nova rally cars go for 45s because they can produce the air needed flow through the venturi.

it cant be that hard then to choke throttle bodies to 35 mm.

[Stuart]

agreed, cant be hard. BUT why havent we seen it done already? its not a huge leap of faith to believe that its not worth the ballache or cost or its just easier to get the same results from carbs... meh

[therealnovaboy]

could using the correct trumpets improve the airflow enough when using bigger throttle bodies,

[therealnovaboy]

agreed, cant be hard. BUT why havent we seen it done already? its not a huge leap of faith to believe that its not worth the ballache or cost or its just easier to get the same results from carbs... meh

untill now as its easier for me to tune an ecu than carbs as i have never tuned carbs before and my brother maps his car himself all the time using a wide band lamda sensor and a hill.

[Stuart]

just use an MPI inlet + injectors etc and do it that way. identicle power/torque can be gotten from the 1.6 8v with aftermarket management and simiar other mods as carbed versions... do it that way imho