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Thread: Pinto power. Bike carbs vs webers.

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    Pinto power. Bike carbs vs webers.

    I just seen this on facebook. A boy who i have been talking too put these up. What does everyone think?

    I though I'd share this with you guys. Just been off to have my DCOE45's jetted and tuned.


    Background info. Pinto Big valve ported and polished head, FR33 cam. H&H electronic ignition.


    First run is fitted with zx6-r bike carbs and an Ashley 4-2-1 manifold.


    Second run is fitted with 45's and a 105 speed 4-1 manifold.


    The difference (loss) in torque low down is unbelievable. Although top end power is defiantly improved and there for longer.

    I think the 600cc carbs are too small for a 2000cc engine and would be better with carbs off an r1 really but i prefer this graph as it looks like a good driveable road engine.



    I'm sure the webers are running a 38mm choke would they be better with a 36mm choke fitted?

    Last edited by freddy686868; 24-10-2015 at 18:04.

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    Re: Pinto power. Bike carbs vs webers.

    My eyes are trying to overlay the graphs but is not working. Is this engine making 110 Bhp wheel power? For this kind of power your 45 carbs are way to big, let alone 38 mm chokes.

    4-1 are not build for torque.

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    Re: Pinto power. Bike carbs vs webers.

    Quote Originally Posted by onyd View Post
    My eyes are trying to overlay the graphs but is not working. Is this engine making 110 Bhp wheel power? For this kind of power your 45 carbs are way to big, let alone 38 mm chokes.

    4-1 are not build for torque.
    I'm not sure if it is wheel power or flywheel power sorry.

    What would you recomend?

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    Re: Pinto power. Bike carbs vs webers.

    The bike carbs have near enough 20bhp more at 4000rpm compared to the 45's, that's a hell of a difference and would definitely be noticeable in the real world; it's going to be much more driveable.

    It must be wheel horsepower we're talking, after all a standard 2l is rated at what, 100bhp in early carb/RS tune and 110bhp or so in later Sierra injection form?

    I'd hate for those mods to not be making more than a standard injection pinto!
    Last edited by MegatronUK; 24-10-2015 at 19:19.

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    Re: Pinto power. Bike carbs vs webers.

    Quote Originally Posted by MegatronUK View Post
    The bike carbs have near enough 20bhp more at 4000rpm compared to the 45's, that's a hell of a difference and would definitely be noticeable in the real world; it's going to be much more driveable.

    It must be wheel horsepower we're talking, after all a standard 2l is rated at what, 100bhp in early carb/RS tune and 110bhp or so in later Sierra injection form?

    I'd hate for those mods to not be making more than a standard injection pinto!
    I thought the same too the bike carbs look to pull nice and clean from low down.

    Or is it the manifold killing the low down torque? If it is he is not willing to swap the manifold out as it looks nicer than the ashley system.

    Power is at the wheels too, i just asked him.

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    Re: Pinto power. Bike carbs vs webers.

    A basic back of envelope calculation of how much piston volume the ZX6-R shifts compared to a 2l Pinto:

    14000rpm x 0.660litres = 9240 litres/minute
    7000rpm x 2.0litres = 14000 litres/minute

    That's a really crude comparison, completely ignoring the volumetric efficiency of each design, but perhaps shows what the theoretical flow rates are like. Swap in the details of a 900/1000cc class bike though, and you can see that's why people seem to use R1 (and similar) carbs for Pintos and the like; in terms of outright litres/minute they're spot on.

    Doesn't seem to be causing much in the way of problems for the engine above though!
    Last edited by MegatronUK; 24-10-2015 at 19:29.

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    Re: Pinto power. Bike carbs vs webers.

    The bike carbs are perfect in your case. But I think the difference is bigger as the carbs only. Question is, where they jetted correct (as far as you can get 45 DCOE with 38 mm chokes jetted correct on this underpowered car). And because of the torque shape, I feel the exhaust must have his part of the deal to. Specially because the small bore 4-2-1 Ashley is hard to beat when it comes to low end torque. Anything else will already fail. Was it 4-1 bit bore? It's a typical shape of a way to big, to short 4-1 exhaust if you ask me. Believe me I see this models very often.

    Top end power is not really improved. It's just screaming a bit longer.

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    Re: Pinto power. Bike carbs vs webers.

    With the 600 carbs he is loosing around 10bhp at 7000rpm so your maths seams right but it would make for a better road engine with the bike carbs imo. Would choking the weber carbs down to 36mm make the bottom end better?

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    Re: Pinto power. Bike carbs vs webers.

    Either way, the figures are absolutely crap for a BVH and Fr33, a skimmed std valve injection head with a decent fast road cam and a set of 40's would make more.

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    Re: Pinto power. Bike carbs vs webers.

    Quote Originally Posted by onyd View Post
    The bike carbs are perfect in your case. But I think the difference is bigger as the carbs only. Question is, where they jetted correct (as far as you can get 45 DCOE with 38 mm chokes jetted correct on this underpowered car). And because of the torque shape, I feel the exhaust must have his part of the deal to. Specially because the small bore 4-2-1 Ashley is hard to beat when it comes to low end torque. Anything else will already fail. Was it 4-1 bit bore? It's a typical shape of a way to big, to short 4-1 exhaust if you ask me. Believe me I see this models very often.

    Top end power is not really improved. It's just screaming a bit longer.

    From what i can gather it is this manifold




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    Re: Pinto power. Bike carbs vs webers.

    For sure.

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    Re: Pinto power. Bike carbs vs webers.

    a 4-1, not a good pipe for a pinto......the primaries need to be longer.

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    Re: Pinto power. Bike carbs vs webers.

    Quote Originally Posted by onyd View Post
    The bike carbs are perfect in your case. But I think the difference is bigger as the carbs only. Question is, where they jetted correct (as far as you can get 45 DCOE with 38 mm chokes jetted correct on this underpowered car). And because of the torque shape, I feel the exhaust must have his part of the deal to. Specially because the small bore 4-2-1 Ashley is hard to beat when it comes to low end torque. Anything else will already fail. Was it 4-1 bit bore? It's a typical shape of a way to big, to short 4-1 exhaust if you ask me. Believe me I see this models very often.

    Top end power is not really improved. It's just screaming a bit longer.
    He had them jetted on the dyno. Wether the tuner is a pro or not i don't know.

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    Re: Pinto power. Bike carbs vs webers.

    Quote Originally Posted by Erikmex View Post
    Either way, the figures are absolutely crap for a BVH and Fr33, a skimmed std valve injection head with a decent fast road cam and a set of 40's would make more.
    What would an ideal set up be then?

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    Re: Pinto power. Bike carbs vs webers.

    Depends what your after, as a comparison i had 163hp from a Pinto similar spec to this on 38mm chokes and an FR33, either the head is very poorly done, not enough compression, poor exhaust......the Pinto i mention also pulled really well from 2200rpm with 10.8:1 compression and a smooth AFR of 12.7-13.4 across the rev range.

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    Re: Pinto power. Bike carbs vs webers.

    This is indeed your problem, no way out. Who the f*ck is producing such crap? I don't think they have used a dyno to develop this manifold.

    Switch back to Ashley and problem solved. Decrease chokes to max 34mm if you want to stick with 45 DCOE. Smallest available I believe. We sometimes build 32 mm for 45 DCOE to help customers out of there mistakes.

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    Pit Crew Decade Plus User MegatronUK's Avatar

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    Re: Pinto power. Bike carbs vs webers.

    Quote Originally Posted by Erikmex View Post
    Either way, the figures are absolutely crap for a BVH and Fr33, a skimmed std valve injection head with a decent fast road cam and a set of 40's would make more.
    What do we feel such a setup should be making at the fly if tuned correctly; 160bhp or so? that translates to what, 120bhp? at the wheels?

    I had a similar engine (injection pinto, ported head but retained standard injection valves, -060 head skim, +060 pistons, FR32, R1 carbs and a 4-2-1 manifold), it always ran a little more lumpy at idle than standard but pulled cleanly. Never had it dynoed but would have expected something like 140bhp flywheel?

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    Re: Pinto power. Bike carbs vs webers.

    Yeah id say about 160, 120 ish at wheels depending on g/box

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    Re: Pinto power. Bike carbs vs webers.

    Onyd...your always a man for smaller chokes....id say 36mm chokes.

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    Re: Pinto power. Bike carbs vs webers.

    Looking at that manifold, as well as what onyd and Erikmex have already said about primary lengths, shouldn't the collector lead to something much larger diameter? To me it doesn't seem much larger diameter than one of the primaries.

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    Re: Pinto power. Bike carbs vs webers.

    Agree re. the manifold...it looks terrible, someone has went to the bother of making nice primaries then cut them off short and welded them into a single pipe...not good.

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    Re: Pinto power. Bike carbs vs webers.

    that looks a lot like a 105speed manifold

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    Re: Pinto power. Bike carbs vs webers.

    JEM Engines done the headwork the head is aimed at 10.8/11-1 cr. the compression tester is only bringing up 140psi on the bottom end though. Could that be a problem? I don't know what psi a healthy pinto should ne making.

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    Re: Pinto power. Bike carbs vs webers.

    Quote Originally Posted by Graham View Post
    that looks a lot like a 105speed manifold
    That's the one he is running.

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    Re: Pinto power. Bike carbs vs webers.

    cam will effect pressure shown on a compression test, but 140psi looks very low given the cam and stated compression, i would expect more like 180psi perhaps 200

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    Re: Pinto power. Bike carbs vs webers.

    Quote Originally Posted by freddy686868 View Post
    That's the one he is running.
    i think the manifold was designed giving maximum clearance as possible in mind, something ive heard through the grapevine is that when inital back to back testing was done to decide which manifold worked best was done teh results were mixed up and the one that actually went into production wasnt the best design.

    i do have to say though that the 2.2 i built dazzle used the same manifold and 2 inch system and gave 200bhp with one of my big valve injection heads and an rl31 so the manifold cant be all bad

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    Re: Pinto power. Bike carbs vs webers.

    Quote Originally Posted by Graham View Post
    cam will effect pressure shown on a compression test, but 140psi looks very low given the cam and stated compression, i would expect more like 180psi perhaps 200
    The bottom end could do with a rebuild then.

    He spent a load of money on the manifold and exhaust system too so isn't willing to change it back to the ashley. Shame he didn't do more research into it all or ask you bunch of gurus first.

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    Re: Pinto power. Bike carbs vs webers.

    That does seem rather low compression, especially given the head/cam work. Bottom end may not be too healthy.

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    Re: Pinto power. Bike carbs vs webers.

    Quote Originally Posted by Graham View Post
    i think the manifold was designed giving maximum clearance as possible in mind, something ive heard through the grapevine is that when inital back to back testing was done to decide which manifold worked best was done teh results were mixed up and the one that actually went into production wasnt the best design.

    i do have to say though that the 2.2 i built dazzle used the same manifold and 2 inch system and gave 200bhp with one of my big valve injection heads and an rl31 so the manifold cant be all bad

    With a bottom end rebuild and a change in chokes he might get away with it. He might even have a low compression bottom end.......

    I have told him to join the forum so he might pop up on here later. This place is a gold mine for pinto tuning!
    Last edited by freddy686868; 24-10-2015 at 20:32.

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    Pinto power. Bike carbs vs webers.

    Hi guys, mine is the engine in question. With regards to the bottom end. This is a picture of the Pistons 1 and 4 at TDC.

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    Re: Pinto power. Bike carbs vs webers.

    you sure thats at tdc? with an unskimmed block hi comp engines have the piston about .5mm down the bore, low comp is about 1.5mm down.
    if that engine is actaully a tdc its either got 1600 rods or crank

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    Re: Pinto power. Bike carbs vs webers.

    Hi guys, mine is the engine in question. With regards to the bottom end. This is a picture of the Pistons 1 and 4 at TDC.

    Nice to see you made it to the forum. It's an awesome place to be!

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    Pinto power. Bike carbs vs webers.

    All I know is it's a 205 block. No idea what's in it :/

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    Pinto power. Bike carbs vs webers.

    I'll take a spark plug out tomorrow and try to get an inspection camera in there at TDC tomorrow.

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    Re: Pinto power. Bike carbs vs webers.

    Quote Originally Posted by Graham View Post
    you sure thats at tdc? with an unskimmed block hi comp engines have the piston about .5mm down the bore, low comp is about 1.5mm down.
    if that engine is actaully a tdc its either got 1600 rods or crank

    I don't know no1 and 4 pistons look about 1.5mm from the top of the bore to me.

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    Re: Pinto power. Bike carbs vs webers.

    i think you need to put a spanner on the crank pulley bolt and see if you can get no 1+4 higher up the bores with a little bit of turning of the crank

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    Re: Pinto power. Bike carbs vs webers.

    JEM heads are generally good, i know Eric personally, his big valve heads with an RL31 usually make 165hp +, i compete against an Escort that has one of their engines....a 180hp spec unit that performs very well. Compression, exhaust and too big chokes looks like the issue with this engine.

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    Pinto power. Bike carbs vs webers.

    Pic was taken a while ago when engine was apart. Ill try to get a measurement of the top on the piston to block.

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    Re: Pinto power. Bike carbs vs webers.

    Transit Engine ?

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    Re: Pinto power. Bike carbs vs webers.

    I'll watch this as mine will be in bits soon

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