[DMAC]

My eldest son has just installed some Quad 40mm Delorto side draft carbys off a 2l Audi on his 1.3l 4K corrolla motor. He hasn't got them tuned yet but he reckons there is a real power gain. It is a lot louder though.
Sometimes I think the young ones believe loud=more power.
My question is.
Has any one fitted side draft carbys to their Zuke?
Do they have a float bowl?
Do angles effect their operation?
Would you have to make a new manifold up or just an adaptor?
Would a single one suit or would you go twins or quads?

Just putting feelers out if it would be worth while persuing as an upgrade as I'm finding myself heading down the Gypsy road of mild cam, extractors.

[eldo]

pretty sure nandor is doing this

[ball]

We fitted an SU from a mini to a 1.3 sierra about 10 years ago. It wasn't a hardcore offroader but it went well in a straight line.

It had a supercharger fitted as well which had a bit to do with the performance

With the blower, the single carb was a bit small and restricted the amount of boost that the blower made. I think it ended up with a poxy falcon carby on it when we realised the SU was too small.

[Santos]

there is a fair bit of info on zukwharrie about quad motorcycle carb set ups...
some even showing figures vs webbers and such
sorry no longer have a link

As a rider i can tell you Bike carbs run on quite severe angles like greater than 45 degrees... just look at the racers (granted its mostly fuel injection now but that has only been in the last 6 years or so)

its one of those things i would like to tackle one day. Having a one carb per cylinder has to be a huge tuning advantage, in both power and fuel economy, no uneven rich/lean charge, carb only flowing when the corresponding cylinder is open.

I would suggest if you dont have experience with bike carbs that rather than going for fancy bigbore cv carbs you go for simple small bore fixed jet carbs. The diameter of each intake on an 8v is like 28-30mms. Why run 38-40mmm? (maybe if its dual instead of quad, but even then the stock aisin is 28/32!)

Which brings me to the dellotos, one thing i read constantly about carby tuning is a big diametre carb and a small engine is a bad mix. At full throttle it can dump heaps of fuel but at low throttle the vaccum signal is poor/weak. A smaller carb will have stronger signal

[royce]

you can choke them down a fair bit to make em work on a small engine but I think on rough roads even with extended float vents and stuff they would be a bit shitty

Su's or bike carbs I reckon

[2stroker]

The problem wth fitting multiple carbies to a Suzuki has always been the fact that the Suzuki's inlet manifold design does not lend itself easily to the application, having water jackets and the thermostat as part of the manifold makes a custom manifold a big task. SU carbies or better still their japanese copies have the potential to work well in offroad applications. I run twin side draft hitachi carbies on my LJ, they are excellent at all angles and really enhance the performance of the vehicle.

[royce]

something to think about with multiple carbies as well (especially quads) is at idle there is going to be a fair wack of air pulsing back and forward inside each runner so idle and low down is going to be a bit harder to get right

though higher up its obviously a lot better with straighter ports and so on

[DMAC]

All good comments. My son said that they may have to sleeve them down. Which I gather will make them less than 40mm.

Its sounds to me it maybe worthwhile doing some ground work.
I'll have to dig up the build thread of the guy who was making the manifold for the quad carbs.

2stroker comments on the manifold and thermostat housing had crossed my mind as being an issue.

Ball my son did metion supercharger for the rolla at a later date!

[DMAC]

2stroker wrote:

It has been done before, Brisbane off road legend Chad Debrueys experimented with quad carbs on his 1300 Sierra off road race car in the mid to late 1980's before Suzuki made EFI Vitara's as donor cars for Sierra drivers. Chad had the benifit of access to a dyno and a relative in the motorcycle repair industry. After much R&D, different cam profiles, standard and modified cylinder heads, sets of carbies off different bikes, numerous dyno runs and a few offroad events running the quad carbies he scraped the idea. He had already gone down the same road experimenting with a range of 2 barrel carbies from Japanese cars of the day and was able to make more usable power with these modified 2 barrels. I think the main let down was that the side draft carbies were best suited to open throttle applications and high RPM, and made the suzuki too doughy down low. Unless you were flat track racing any benifit gained in top end was lost getting out of the hole each time you had to back off. I believe he raced with a modified Nissan 2 barrel carbie until he went to EFI. Chad's last set of quads is still sitting on the shelf at the workshop where my son works complete with manifold, airfilters and accelerator cable brackets. I will take some photo's and post them up. Those from Brisbane may remember Chad's night run car in the late 1980's, an LJ50 3 cyl 2 stroke with triple carbies and electronic ignition off a Suzuki outboard motor, it had a custom expansion chamber type exhaust and it was just awesome to hear it on the throttle in the bush..

I think I found my answer.

[JrZook]

royce wrote:

something to think about with multiple carbies as well (especially quads) is at idle there is going to be a fair wack of air pulsing back and forward inside each runner so idle and low down is going to be a bit harder to get right

though higher up its obviously a lot better with straighter ports and so on

Thats where the CV (constant velocity) bike carbs come in. They have a throttle butterfly but also a vacume operated slide valve in front. Hence the slide only opens once the engine vacume demands it. Idle and the transition just above idle is quite good with these type of carbs.

I just fitted a set of 30mm CV carbs onto my 250 v-twin to replace the single 26mm CV carb which fed the cylinders through a siemese intake manifold. The engine is nothing special, just basic 2 valve head redlines at 8000rpm. Idle quality has greatly improved due to no charge robing the siemese manifold had, pickup is instantanous and the torque has picked up all over the rev range. Id say quad 28-30mm CV carbs would wake up the 1.3 quite alot. This size would also match the intake runners diameter. being a sidedraught carb the fuel bowl is situated centrally at teh bottom of the carb, hence effects of angles are minimised compared to a side or front fuel bowl carb.

Dan

[2stroker]

On re reading the initial post it is about multiple carbs on a K series Toyota engine so he dosn't have the complexities of the sierra manifold to deal with. This is a custom manifold to take quad GSXR carbies on a 1300.

[Santos]

yes, that pretty much shows why i want quads... but with a plenum to an airbox... rather than hot-air-sucking-mud-clogging-defect-magnet pods

[DMAC]

2stroker wrote:

On re reading the initial post it is about multiple carbs on a K series Toyota engine so he dosn't have the complexities of the sierra manifold to deal with. This is a custom manifold to take quad GSXR carbies on a 1300.

Exactly went out and looked at my old head a whole lot of water galleries tied up with the manifold but that looks the goods. Agree would have to run a plenum especially to run a snorkel.
Are these comercially available or a custom jobbie?

[2stroker]

They are custom, but the pics will give anyone a good idea of how to build up a set. I have a custom twin side draft 1 litre manifold that still belongs to me but has been in a friends possession for way too long and my sons boss has a set of quads and custom manifold for a 1300.

[zookster666]

What would a re-jetted 1 litre carb be like on a 1.3 would there be any gain in off road performance?

[zookster666]

wrong thread

[Santos]

zookster666 wrote:

What would a re-jetted 1 litre carb be like on a 1.3 would there be any gain in off road performance?

a single one? probably not. A 2 barrell aisin carb has a 28mm barrell with a 99 jet and a 32mm barrell with a 105 jet.
putting a single barrell (40mm?) 1l jet seems like a massive restriction


As for buying the manifold i think it was ' geckocycles' or something like that on zuwharrie does runs of them.
http://bbs.zuwharrie.com/content?topic=80099.15


and here is the great quad bike throttle thread of zuwharrie (102 pages)
http://bbs.zuwharrie.com/content?P=19f4 ... ic=70640.0

and lastly a dyno thread with quad set u at the end

http://bbs.zuwharrie.com/content/topic,82730.0.html

[Santos]

I should add also that the length of the intake effects the power.
In short generally long runner = torque, short runner = hp

one of the hp tuning books i got goes in to detail about how to match runner diameter and pipe length for desired powerband with carb

All important factor that could decide the sucess of a install.
(still think CV should be tackled after sucessfully seting up fixed jet carbs)

[JrZook]

Looking at that dyno thread they got a 1.3 from ~45ish RWHP to ~75 RWHP with quad 32mm CV carbs, 2 inch exhaust and a few other mods! From the run (starting at 2000rpm) they produced more power/torque across the board. Now the neumerical HP figures arnt much the gauge the performance off but the difference between them certainly is.

Dan

[Santos]

55kw (75hp) at the wheels is huge. i could say that more than this would be just braggin rights. if i could have the full 90Nm on the bitumen from 3500rpm to 6000rpm i would be estatic,

its a pretty broad powercurve not some knfe edge peak
(not to mention from an engine that is in no way bigger/heavier or plagued with dodgy bootyfab to get it running. )

wonder what the fuel economy on it is like though..

[JrZook]

What's the std zuk 1.3 output men't to be at the wheels?

[Santos]

dunno, differnt dyno's can give different results but in the same thread is a bone stock 16v 1.6l engine with no exhaust in a sierra(stock manifolds) and it gives 38kw (51 hp), 69nm on the same dyno... so its a good comparison

[JrZook]

Santos wrote:

dunno, differnt dyno's can give different results but in the same thread is a bone stock 16v 1.6l engine with no exhaust in a sierra(stock manifolds) and it gives 38kw (51 hp), 69nm on the same dyno... so its a good comparison

Apparently the G13BA engine is listed on wikki as a 50Kw (~67Hp). Taking drivetrain loss on a sierra as 1/4 therefore ~50RWHP. The G16B is also listed as a ~96HP engine so with the same loss should give ~72RWHP. When I took my weber equip G13A to the dyno it pulled 60RWHP. Seems a pretty feasible output.

Dan