guardian angel
|
| posted on 19/9/12 at 08:25 PM |
|
|
Pinto torque curve when using bike carbs?
This may be a stupid question; but when using bike carbs on a 2l Pinto engine, how do they influence the torque curve?
I ask as I plan on fitting a set of R1 carbs to my 2l Pinto instead of throttle bodies to save cash. They are also replacing a 32/36 Weber carb.
My concern is that they may screw my available torque at lows revs, is this the case? Or is it just a case of correct set-up and timing?
Any advice anyone could give would be great.
|
|
|
|
|
snapper
|
| posted on 19/9/12 at 08:33 PM |
|
|
It does depend on your total setup but more bhp usualy means more torque
I got 128 bhp and 135ft/lbs with a 2.1 Mikunies and an FR32
If you ultimately want torque try the FR30 or FR34 cam
Bike carbs are inherently quite good but of course need setting up, needle position and main jet size is only a quarter of the set up
Idle and air circuits, transition jets, little holes in the carbs uncovered as the butterfly's open all make a difference.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
|
|
|
Mr Whippy
|
| posted on 19/9/12 at 08:36 PM |
|
|
never had bike carbs on a pinto but did fit a carb off a 2.8v 6 to one, torque was so sad it could not pull away in 2nd gear, great flat out though
but was a thirsty sod
If you want all round driveability then stick with the carb you have, there really isn't all that much wrong with it. Look at burton powers
website which will give you honest advice on how to tune the pinto rather than fashion things
|
|
|
chillis
|
| posted on 19/9/12 at 08:47 PM |
|
|
quote:
Originally posted by Mr Whippy
never had bike carbs on a pinto but did fit a carb off a 2.8v 6 to one, torque was so sad it could not pull away in 2nd gear, great flat out though
but was a thirsty sod
If you want all round driveability then stick with the carb you have, there really isn't all that much wrong with it. Look at burton powers
website which will give you honest advice on how to tune the pinto rather than fashion things
+1 Unless you have plenty of power mods lined up then stick with the 32/36. Too much low speed airflow screws up low end torque.
|
|
|
guardian angel
|
| posted on 19/9/12 at 08:48 PM |
|
|
Well the plan is to use R1 bike carbs on Bogg Bros manifold with Piper 285 cam and gas flowed head. Compression ratio up to about 11:1.
My main concern is that the bike carbs won't give me low end torque and then will suddenly come alive at higher revs, which if right would suck!
|
|
|
FASTdan
|
| posted on 20/9/12 at 07:40 AM |
|
|
We ran a stock 2.0 pinto on weber 40's - then lashed up (literally) a set of ZX9's on it in one afternoon. The difference in low down
torque and driveability was night and day - and that was on the standard untouched carbs (including jets) which fueled it fine until 5500rpm.
We also run a 2.3 Duratec on ZX9's and the low end grunt is mind boggling! If anything this set up needs bigger carbs (not really surprising) as
the grunt starts to tail off high up.
Airspeed shouldn't be much of an issue given the variable venturi. I cant believe for a minute you will be disappointed going from a twin choke
to R1 carbs.
NEW danST WEBSITE NOW LIVE! Bike carbs, throttle bodies and more......
http://www.danstengineering.co.uk/
|
NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
|
guardian angel
|
| posted on 20/9/12 at 08:14 AM |
|
|
Great, thanks for the advice
|
|
|
snapper
|
| posted on 20/9/12 at 08:39 AM |
|
|
11 to 1 is high for standard pistons, one bit of detonation ( pinking) and the ring lands will shatter
You'll have to retard ignition and set peak advance at 3,600 to 34 degrees this will reduce max power.
If the carbs are set up and delivering the right fuel ratio at the right time you will get what the engine is built to deliver.
You would get similar figures to Webers as you are running 1 choke per cylinder
If there was a difference it would be small
The standard 32/36 carb won't work well with the cam you propose mainly due to the restrictive inlet manifold and the vacuum secondary, the FR30
and FR34 are better.
[Edited on 20/9/12 by snapper]
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
|
|
|
mcerd1
|
| posted on 20/9/12 at 10:47 AM |
|
|
^^ what he said, it might be better to just do a light skim on the head and take the CR up to somewhere between 10.0 and 10.5
I've gone for ZX9R carb's (very similar spec to R1 carb's but cheaper at the time) on a bogg bros manifold with a 285 cam
its a std. EFI head with std. valves and the only mod (for now) is 3 angle seats & bronze guides.
also got megajolt to deal with sparks
I splashed out on a not-so-locost steel bottom end with forged pistons so I'm aiming for ~11.5:1 CR 
I guess I'll find out if I'm right once its running 
[Edited on 20/9/2012 by mcerd1]
-
|
|
|
