Opinions wanted on quality of porting job

[snapper1]

I prefer a large Pipercross filter
If I had the money a Pipercross air box and cold air feed would be nice as air temp under a 7 bonnet can be high

[Graham]

re filters, these days in the bike world its recond that dual filters are better than the singles you tested, which i can well imagine as the have greater surface area

[FASTdan]

A very interesting topic indeed! Nice to see some side by side testing and I am pleased to hear that the Bike carbs held their own (for the most part).

How do we think 48mm bike carbs would flow compared to 48mm webers? As I just happen to have a set ready to go on our 2.3 Duratec hehe.....

[FASTdan]

Left is a a set of 40mm ZX9R's - bless, they'd almost fit inside the new ones.....

[RWD fords rule]

Being that you are comparing modified 45's to the standard BC's is there a way to modify the BC's in order to improve flow or is just a case of the over ID of the carb body determines maximum flow potential?

Cheers

Matt

The 45mm carb I was testing is std with a 36mm choke

I will make a video with the modified parts fitted that I have been working on vs the R1 carbs and also modified 45's vs std 48's with 38mm chokes

The Bike carbs could be modified also but there is less room for modification, narrowing the throttle shaft would be the first place to look at as it is taking up quite a bit of the 40mm open area, 40mm slide throttle would flow considerably more air

Bike throttle bodies are also a good option, you can space them out to suit your engine and made a fairly simple inlet manifold, they will flow a lot of air, Hayabusa TB's have 46mm throttle plate and a 42mm minimum ID, they will easily out flow any production 4 cylinder bike carb I am aware of

[Graham]

it would be a lot more work to use them but if you want really big tb's you need to look at V twins, my TL1000 has 52mm tbs, i believe some ducati are bigger still

[RWD fords rule]

Completely agree Graham, I was expecting the single air filters to restrict flow quite a lot as they don't have enough surface area as you said, twin filters would be much better and most likely not restrict air flow at all

FASTdan, are they the 48mm bike carbs you are talking about in the right of the picture? I have never heard of any bike carb with a larger throttle plate than 42mm to suit a 4 cylinder engine, there are larger bike carbs to suit 2 cylinder V engines but they aren't usable/adaptable to suit 4 cylinder engines as far as I know, if you have found very large 4 cylinder production bike carbs let us know what bike they were fitted to


Cheers for the comments guys

I must say TS is a great forum with lots of knowledgeable people, learned a lot over the past 7 or so years, for example this current flowbench is loosely based on Graham's design with 4 motors and a few other differences but still quite similar, most likely would not have built one if not for his inexpensive flowbench build thread, even though I will be building a new flowbench soon this one has been invaluable for learning how flowbenches work and what I want from the new one

[Graham]

I must say TS is a great forum with lots of knowledgeable people, learned a lot over the past 7 or so years, for example this current flowbench is loosely based on Graham's design with 4 motors and a few other differences but still quite similar, most likely would not have built one if not for his inexpensive flowbench build thread, even though I will be building a new flowbench soon this one has been invaluable for learning how flowbenches work and what I want from the new one

cool, i have to say the forum does encourage the "have a go" mentality which is what made me think about having a go at a diy flowbench in the first place, although strangely i am considering buying a proper superflow one! but thats only because i think it would better fit with a professional business needs and client expectations

[FASTdan]

FASTdan, are they the 48mm bike carbs you are talking about in the right of the picture? I have never heard of any bike carb with a larger throttle plate than 42mm to suit a 4 cylinder engine, there are larger bike carbs to suit 2 cylinder V engines but they aren't usable/adaptable to suit 4 cylinder engines as far as I know, if you have found very large 4 cylinder production bike carbs let us know what bike they were fitted to

Hi, no unfortunately they are not from a 4 cylinder but rather a V-twin of some sort. There's no reason they cannot be used on a 4 cylinder - they are wide, meaning a minimum spacing distance of 93mm (which is fine for most 1800+ capacities such as Zetec, Duratec, C20XE, Pinto etc) and I am confident I can make the manifolds to suit. They will also require a very custom throttle linkage, but nothing exceptional.

We did a project in conjunction with a Jaguar specialist using those carbs on an AJ6 engine for a race prepped Jag - recently dyno'd and track tested initial reports were very positive when compared to the old 45's set up. Here's the manifold mid-welding:



I plan on replicating what was done there on our 4 cylinder 2.3 that currently runs ZX9R's.

[RWD fords rule]

i am considering buying a proper superflow one! but thats only because i think it would better fit with a professional business needs and client expectations

My advice is don't buy a Superflow flowbench, I know that might sound controversial but imho superflow 110 is very over priced for its flow capability, I know there are a lot of good tuners using them but they really are a toy imho, superflow 400 and 600 can flow a lot more air but have issues with under reading CFM approaching their maximum capacity, the 600 especially suffers from turbulence at its higher flow rates

Imho there is only one bench I would build and it is the PTS flowbench, it has proven to have higher accuracy than SF600 and will flow up to 600CFM @28" or can be used with less motors no problem and add more later on if needed (up to 8 motors total), I can send you the build plans I purchased foc if you like Graham, it is a very simple clever design with no risk of air leaks, not trying to slate the blue machines but this is just what I have learned, for the price of a second hand SF110 you could build a 600CFM PTS flowbench which WAY higher flow capability and higher accuracy, suck and blow testing, they also sell CFM calculating electronics that I will soon be buying for a reasonable price, the flowbench is also a compact unit around the same size as my current flowbench so it does not take up much room either

Very handy to have more flow capability when you need it, testing at 10" is ok but imho for best results 28" will give higher resolution, when testing carb flow rates on a SF110 the flow depression would be less than half what I was measuring at on my bench

[RWD fords rule]

FASTdan

Let us know what engine those carbs are off, are they easy to link together? can you link say 2 sets of V twin carbs together for a 4 cylinder engine or have you got to buy 3+ sets to make one set for a 4 cylinder to get the throttle linkages to work if you know what I mean

[FASTdan]

FASTdan

Let us know what engine those carbs are off, are they easy to link together? can you link say 2 sets of V twin carbs together for a 4 cylinder engine or have you got to buy 3+ sets to make one set for a 4 cylinder to get the throttle linkages to work if you know what I mean

I will as soon as I know lol. The guy with the Jags sourced them and even he cant recall - but we've got more on the way and he'll be in touch with the supplier to find out.

They are simple to mount in a 4 cylinder configuration (same fundamental casting design as any others) but 3 out of 4 of the throttle spindles require some modification (cutting shorter, then turning down and adding detail to attach some sort of link arm). It could be possible to utilise the carb-carb linkage from normal bike carbs but these require about 20mm of space between each carb, resulting in 103mm spacings (too wide for most 4 cylinders - though the manifold could be made to accomodate the difference). So we'll be adding a link arm to each carb individually (which only requires about 10mm inbetween, so 93mm spacings), then linking to a remote common throttle bar with rosejoint links. They also handily come with a TPS already mounted.

2 sets are required to make up a bank of four. Not exactly your 'simple' bike carb conversion anymore but its something a bit different :-)

[RWD fords rule]

Modified 45 DCOE vs 48 DCOSP x 38mm choke vs R1 Keihin

[snapper1]

So with the evidence presented what would be the limit for R1 carbs on a Pinto
It would be good to understand where they fit in tuning options
Better than 40's
As good as 45's up to ( insert bhp/revs etc) unless you modify the 45's

This is a great thread the collective knowledge moves forward
For me it means I can start to make more informed decisions

[RWD fords rule]

Yes R1 = flow more air than twin 40's ever will

R1 flows practically the same air as a std 45 with 36mm choke, ok maybe the same as a 36.50mm choke but the difference is quite small between the two at that choke size

37mm+ chokes in std 45mm carbs flow more air than R1

So any power you can get from an engine running on 45's with 36mm chokes you can expect to get from R1 carbs

There is no clear definitive answer for how much bhp the R1 carbs can support as for example a 1300xflow is going to make a lot different power levels to a 2.0 pinto or 2.0 XE etc, on the 1300 xflow R1 carbs would be capable of flowing enough for for a full race engine, talking 140bhp+, on a std or mild 2.0 XE at a guess they could make 170 to 180bhp, on a full race XE they might make 200bhp but the engine would be choked not having nearly enough air flow and would make 50bhp+ more on 48's with 42 to 44mm chokes or throttle bodies

That is how it goes, one engine needs more air flow than another, so we can't definitively say R1 carbs flow enough air for X amount of power, however as a loose power figure I would suggest 160 to 180bhp is what I would expect from them on an engine that is not under carbed or over carbed in terms of flow rate

The higher the max rpm power the higher the air flow needs to be, that is why I gave an example of R1 being able to give all the power a 1300xflow can give, and being able to support a std or mild 2.0 XE for fast road on the other end of the scale where it would be making its power at lower rpms but with much higher cylinder cc and head flow

About the modified 45's I did not show a shot down into that carb since that would give the game away, there is not one person in the UK or EU using very extensive carb mods like this, once I get the parts cnc machined, hopefully soon then I will start selling them, already tested in a set of 50's in my friends engine that had been modified by a very experienced tuner from the US and they are performing exceptionally well, I feel heavily modified 45's like this are the way to go with a lot of engines as we all know 45's perform a lot better at low to mid rpm than 50's or 48's, also planning on the same modification with 48's which will make them flow enough air to support any engine you can think of, using smaller carbs with smaller throttle plates is always an advantage as it makes the engine much easier to drive out of corners, for a give flow rate you have to press the throttle more exiting a corner vs larger throttle plates which are harder to control, smaller throttle plates give more confidence to the drive knowing he can get on the gas pedal straight away exiting a corner and can get more of a drive away faster, same goes for race bikes, that is why most of them use progressive throttle linkages that open the throttle slow initially and then much faster towards full throttle

There is also air speed to think about, the smaller the carb bore ID the greater the velocity, this increases cylinder filling from mid to high rpm's, in terms of velocity smaller is better, too small is bad but if we can not restrict high rpm power and use the smallest throttle plate + car or TB inner diameter and inlet manifold ID + trumpet ID the higher the air speed will be and the more power and torque the engine will make, it is a given on a dyno not just a theory

For all those reasons I think that R1 is ideal for a 2.0 fast road / milder competition engine or full race 1.3 and possibly suitable or a heavily tuned 1.6 xflow without restricting top end power, expecting to see for example 200bhp from a 2.0 pinto engine on R1 carbs is unrealistic imho but I would expect to see 180bhp or so on an engine making 200bhp with heavily modified 45's or std 48's


With 42mm production bike carbs I think that you could add 10bhp to those power levels for the larger cc engines as a safe bet and maybe a little more, only unbiased dyno testing can prove this for sure but this is my best guess from what I have seen

Larger bike carbs are a different story, the 48mm ones mentioned should be able to supply enough air to beat std 48's and 50's depending on shape/design of course

Cheers for the comments guys

[Matt75]

Great stuff Jason,

You really seem to be enjoying your handiwork on this thread. I really appreciate the lengths you are going to to make the unintiated undertand the reasons behind the results.

As stated I plan to use the R1 carbs on the engine and we are expecting around the 160rwhp (going by other engines that have been built) so we will see what power we get on the BC's and go from there.

Great stuff.

Matt

P.S. is it possible to change the title and make it a sticky? Mods?

[Craigorypeck]

These findings defo deserve their own thread. Good work jason.

[Group4_Mark2]

I have also built my flowbench as a result of you thread. I had read about, and thought about doing one for ages but until I saw yours being built I did not get up and do it.

This forum for sure has remained one of the best for open discussion without too much argument that is seen on other forums.

Enjoying this thread.

[escortinadriver]

Jason,

Can you empty some of your private messages,

Thanks Shaun

[RWD fords rule]

Can you empty some of your private messages,

Thanks Shaun

Done

[RWD fords rule]

Cheers for the comments guys

[capri dave]

An old racers trick is to cut off one of the supporting legs from the auxiliary venturi's on 45 webers...

[RWD fords rule]

An old racers trick is to cut off one of the supporting legs from the auxiliary venturi's on 45 webers...

That is not a practical mod, as the outer ring is less than 1mm thick it leaves the aux vent extremely weak..

[Graham]

That is not a practical mod, as the outer ring is less than 1mm thick it leaves the aux vent extremely weak..

yes and no, ive done it (along with thinning shafts and slimming the butterfly retaining screws) and afterwards the carbs did many seasons racing, although as jason says it must leave them weak, if you that desperate for a bit more flow perhaps its time to buy some bigger carbs

[RWD fords rule]

if you that desperate for a bit more flow perhaps its time to buy some bigger carbs

Or heavily modify them, thinning the aux vent leg is fine, removing it is not imho

[capri dave]

That is not a practical mod, as the outer ring is less than 1mm thick it leaves the aux vent extremely weak..

yep, im not disagreeing with you... its still done though by people looking for that competitive edge.

ive even seen people constructing little ski ramps made from chemical metal (in effect a kind of very strong body filler) in the inlet ports of pinto cyl heads...

and repairing carb bodys with Devcon and tin foil where the fixed chokes have been bored out too far.

all old racers tricks...

[RWD fords rule]

Not to sound big headed but the carbs we are currently using are Light Years ahead of any of those mods... think WAY outside the box and then some more, I am working on improving them further (twin 50's), once done there literally will not be much of a difference between them and TB's, I have done some pretty intensive flowbench testing on 45's and 48's/50's from part throttle to WOT with all the available chokes and customs made a few chokes with HUGE FLOW yet the part throttle vacuum signal strength at the main jets is that of the Smallest choke size available..

The best port filler to use is Belzona 1111, injection ports can be raised considerably over std, around 6 to 7mm higher port roof at the port entry and more like 10mm+ taller on the port floor, make the port around 3mm wider each side and D shape with a flat bottom this is the best shape with pinto ports without going full downdraft, there is a company in the UK developing a full downdraft head which you may see towards the end of the year, if done correctly this will change the way some people look at pinto's that is for sure, think a realistic 230bhp+ or 250bhp pub talk!

[Matt75]

So just thought I'd give some closure to this thread

We decided on an all out race engine in the end on 48 DHLA's

It was dyno'd at 189ish hp which was a great result I think

Few pics and the dyno graph

Cheers

Matt

[Graham]

nice result

[hawk1903]

Hi Matt,
Which camshaft you have used in this build ?

[Matt75]

Hi Matt,
Which camshaft you have used in this build ?

Hey Mate

It's a custom grind but has the following -

.536 lift inlet and .510 lift on exhaust and 316 duration inlet and 305 exhaust.

Cheers

Matt

[hawk1903]

Hi Matt,
Thank you very much for your reply. That cam has some serious lift for a non roller profile.
Do you happen to know the Inlet valve lift @ TDC ?
Cheers

[Matt75]

260 @ 50 rings a bell but im a real novice with this stuff.

Cheers

Matt

[hawk1903]

260 @ 50 rings a bell but im a real novice with this stuff.

Cheers

Matt

OK. No problem. If you have a chance to ask your engine builder about the TDC cam timing figure, it would be very nice. Thanks very much again.
Cheers,
Kerem

[Matt75]

Will do.

Cheers

Matt

[Flighter]

there is a company in the UK developing a full downdraft head which you may see towards the end of the year, if done correctly this will change the way some people look at pinto's that is for sure, think a realistic 230bhp+ or 250bhp pub talk!

This quote is from Oct. 2013 - any further word on this?

[mariors2000]

hi mat

great power what compression are you running in engine

cheers mario.

[mariors2000]

hi all cam seems to be ht1 e spec or very close to it

cheers mario.

[Matt75]

hi mat

great power what compression are you running in engine

cheers mario.

Hi Mate,

The Comp ratio is about 11.2 running on 98 octane

Cheers

Matt

[mariors2000]

Hi matt who build your motor cheers Mario