[holdenrules]

Hey all just wondering what carbys people are using for a blow thru carby turbo setup?? will the stock one work without callapsing the float. i really want to keep the stock carby. any help would be great. also pics of this setup would be good to see to thanks

[whincup]

off topic, but you live in same town as me... i havent seen you're zook round at all. of course, i am assuming your wheels arent really that big...

[Brett]

1st thing you need to tell use is how much boost your going to put in the engine. low psi it will work

[holdenrules]

hey mate, havent seen you around either, i change zooks a fare bit and this is my fourth, bought it as a shell and chasis and building it up so you will see it around soon.
As for engine, its a 1.6 vitara bottom end bored 40 thou over size, decompretion pistons i bought from the us, lowered comp to 8.1. fully worked and ported head with lumpy cam. stainless steel custom manifold with ihi rhb5 turbo. yet to sort out intake. im not going injected so dont suggest please. i am wanting to run about 10 pound boost but what will i have to do with the carby. i havent done this setup before but have done a draw thru. please let me know. cheers

[Gwagensteve]

holdenrules wrote:

im not going injected so dont suggest please. i am wanting to run about 10 pound boost but what will i have to do with the carby. i havent done this setup before but have done a draw thru. please let me know. cheers

You are joking aren't you?

Can anyone, anywhere tell me if there has EVER been a factory blow-through installation that ran 10psi? I know lotus played with blow through with webers (I think?) but they boxed in the webers so there was no pressure differential... and they went EFI as soon as they could.

holdenrules - I can't seriously believe you would spend what you have (in time alone, even if not money) on a motor and then try and run it with a carby, so pretty much leaving it's durability to chance. Go EFI and get it properly tuned. Apart from anything else, the airflow between an off boost 8:1CR engine and an engine @ 10 psi is a huge issue for a (stock, based on you outers post) carby to contend with.

It will drive like crap. It might be cool in a performance road car to have crappy drivability, but it will suck in a 4WD. Put a SOHC 16V head on it and inject it.

Steve.

[losfer]

blow through sucks

x2 what steve said

[Brett]

two ways you can do it ( i have never done it with a sierra carby)

1, box the whole carby in a sealed box (easy way to do a holly) and tune from there. this way stops blowing seals so easy and it pretty easy to tune, its just like tuning a normal carby pretty much

2 rebuild the carby with every thing new and a good float, and use a boost ref reg and go from there. this is what i would do

things you need to think about is if the paper gaskets are going to hold up, if you have to o ring (or can) the butterflys, your curve in the dizzy and the list goes on

because it hasn't been done before its going to be trial and error. tuning is the hard bit. i would use a vit carby as well.

put a pic up of the pistions, i want to see where the ring groves are sitting

[holdenrules]

haha rito mate im gunna give it a go, im not going fuel injected i want to try something different, im a diesel fitter so im sure ill work it out, trial and error.

[JrZook]

holdenrules wrote:

haha rito mate im gunna give it a go, im not going fuel injected i want to try something different, im a diesel fitter so im sure ill work it out, trial and error.

Well good luck! Give it a go. Not sure what knowledge background you have boosting petrol engines but I assure you they are a tad more complex than their diesel counterparts. The sierra carby is particular unattractive for blow thru setup with its maze of vacuum actuators and vacuum lines not to mention the poor accelerator pump seal setup. VW guys have played alot with this in the past using simple weber carbs and have had varying success. Your cam specs if set up for the original NA setup will be wayyy off to suit boosted conditions, it still most likely will work tho. Timing will play a big role in trying to keep the engine alive and will have to be dropped back considerably under boost.

Dan

[Highway-Star]

What is peoples phobia of fuel injection? or is it an unjustified love of carburettors? or both?

Injection is awesome...no wait, its super duper mega totally wicked killer awesome sick!

I hate electronics, and am useless with them.... but I hate carburettors more!


oh and I'm not even talking about boost, just N.A. Boosted makes EFI even more attractive

[atari4x4]

Highway-Star wrote:

What is peoples phobia of fuel injection? or is it an unjustified love of carburettors? or both?

Injection is awesome...no wait, its super duper mega totally wicked killer awesome sick!

I hate electronics, and am useless with them.... but I hate carburettors more!


oh and I'm not even talking about boost, just N.A. Boosted makes EFI even more attractive

x more than 1,000,000,000,000,000,000,000,000,000,000,000,000

but hang on, he is a deeseal fitter... maybe all the wires n stuff scare him.

turbo carbies are soooo 1980's it's not funny

[Fatzook]

atari4x4 wrote:

.

turbo carbies are soooo 1980's it's not funny

you mean 1950's

[JrZook]

Highway-Star wrote:

What is peoples phobia of fuel injection? or is it an unjustified love of carburettors? or both?

Injection is awesome...no wait, its super duper mega totally wicked killer awesome sick!

I hate electronics, and am useless with them.... but I hate carburettors more!


oh and I'm not even talking about boost, just N.A. Boosted makes EFI even more attractive

The issue here is that a carby is essentially a dumb mechanical device hence it opens up alot of opportunity for back-yarders and hobbyists alike to modify and make run under non-standard conditions. Things can be changed with relative ease as well as cost which makes them appealing. Its no rocket science with the theory behind carbs and how they deliver fuel. They are not a 'black box' as is the case for EFI systems and can be made to run close to ideal without specialized equipment. In saying all this their downfall lays within their simplistic operation. No compensation for changing air density or temperature, fixed accelerator pump control etc as well as fuel delivery curve modification essentially limited to changing idle and main jets. EFI is a far better method for fuel delivery using complex algorithms to determine the ideal amount of fuel required for the current running conditions.

Placed under the same conditions how many of you could modify or tune your stock EFI fuel system to accommodate boosted operations? How does it calculate the fuel requirements? How can you change this? Yes it can and has been done but fewer understand the concepts of fuel deliver with EFI compared to that of old-skool carbies.

My 0.5c Dan

[Highway-Star]

JrZook wrote:

Highway-Star wrote:

What is peoples phobia of fuel injection? or is it an unjustified love of carburettors? or both?

Injection is awesome...no wait, its super duper mega totally wicked killer awesome sick!

I hate electronics, and am useless with them.... but I hate carburettors more!


oh and I'm not even talking about boost, just N.A. Boosted makes EFI even more attractive

The issue here is that a carby is essentially a dumb mechanical device hence it opens up alot of opportunity for back-yarders and hobbyists alike to modify and make run under non-standard conditions. Things can be changed with relative ease as well as cost which makes them appealing. Its no rocket science with the theory behind carbs and how they deliver fuel. They are not a 'black box' as is the case for EFI systems and can be made to run close to ideal without specialized equipment. In saying all this their downfall lays within their simplistic operation. No compensation for changing air density or temperature, fixed accelerator pump control etc as well as fuel delivery curve modification essentially limited to changing idle and main jets. EFI is a far better method for fuel delivery using complex algorithms to determine the ideal amount of fuel required for the current running conditions.

Placed under the same conditions how many of you could modify or tune your stock EFI fuel system to accommodate boosted operations? How does it calculate the fuel requirements? How can you change this? Yes it can and has been done but fewer understand the concepts of fuel deliver with EFI compared to that of old-skool carbies.

My 0.5c Dan

Thats valid....but!

Me personally, If I was looking at doing this to an 8V G13 motor, I would want to do it properly, I would not stuff around with 2nd rate crap, because the whole point of boosting something is to achieve performance gains, so lets get everything running at its best? or at least better than standard.

So keeping it simple, I'm sure with some help, allot of people would be capable of using a mega squirt system, with simple TBI running open loop. This is hardly the wiring nightmare that my GV motor is, and if you make it yourself, you would gain a substantial understanding of how it works which is very useful if anything did go wrong with it. I was recently considering megasquirting the F10a in my LJ80. I have the carby running better now, but I have not scrapped the idea. I have no clue how to do it really, but I would research my arse off, and figure it out, because I know in the end, it will shit all over the crappy little carby if I get it right . What I'm saying is basically short term pain for long term gain . Do the research, and you will have a far better end result. You could alternately just pay someone who knows their stuff to do it for you...

I'm sure I could make arguements for EFI and against carburettors to I'm blue in the face, and maybe everywhere else....but you are right, some people like dumb mechanical devices

[finlay113]

aparently a range rover carby is easy to setup on a sierra turbo, and there simple. work a bit like a motorbike carb,

[JrZook]

finlay113 wrote:

aparently a range rover carby is easy to setup on a sierra turbo, and there simple. work a bit like a motorbike carb,

Constant velocity type carbies. Probably the best type you can get in terms of fuel metering capabilities.

[royce]

depending on model they can work or be useless

HIF style SU will jsut about work with only jet and spring changes, HS style you need to work out pressurising the float bowl and changing the float

Problem is you need to be a fair guru to set them up and they wont pass emmisions

[Gwagensteve]

Why does anyone think EFI is complex? The flowchart for EFI operation - inputs vs outputs etc is very simple and logical. In fact, it's simpler than the flowchart for carby operation.

However, the ability for an EFI engine to run in closed loop, thereby "self tuning" to achieve an ideal A/F ratio in cruise, and EFI engines self diagnostics makes the just amazingly easier to work with than a carby.

Steve.

[JrZook]

Gwagensteve wrote:

Why does anyone think EFI is complex? The flowchart for EFI operation - inputs vs outputs etc is very simple and logical. In fact, it's simpler than the flowchart for carby operation.

However, the ability for an EFI engine to run in closed loop, thereby "self tuning" to achieve an ideal A/F ratio in cruise, and EFI engines self diagnostics makes the just amazingly easier to work with than a carby.

Steve.

May be simple when you glance over the top with a simple flow chart, but try designing one and tell us how simple it really is then. The fueling algorithms get pretty chunky

Anyway im pretty sure old mate is stuck on setting up a boosted carby system. Any reason to why you want to go blow thru instead of draw thru for running the low boosts your after?

Dan

[holdenrules]

than the info guys, um i want blow thru casue of the simple fact i had a draw thru setup on my turbo gemini and it ran like shit becasue of the carby used. its now fuel injected. i dont really have the time to go injected but i would love to. for now it will be blow thru so i have a car to drive. and i do have have nearlly everything except the carby. i was thinking a xf carby apparently they can handle a bit of boost.

[losfer]

you dont have the time to go injected , well multiply that by ten and thats the time you will spend trying to get a reliable blowthrough carby boosted setup ...

[Gwagensteve]

Xheaps.

If you don't have time to tune EFI, you certainly don't have time to set up a turbo. Why not a stock carby for now and take your time assembling an EFI/turbo package.

If you think your suckthrough setup was a dog (where you don't have to get the carby to take boost) why do you think trying set up a blowthrough would be better?

Steve.

[eldo]

i have been here and done this about 12 years ago with a 2.6 astron. i had an SU about 45 or 50mm it ran ok. the car did 12 sec on this setup. this same engine in another car prior to my carby setup was running high 10's and with nos high 9's. honestly mate stop wasting your time with a carby, it will never run right ever, do a custom XF falcon throttle body with the single point setup on an after market fuel computer, now that is something different and very simple, it will also be tunable with a hand held or a laptop. it will also mean that intercooling will be easier etc etc.
i can understand that you want to be unique, but going back 20 years in technology to do it is plain ignorance. how long have you been a fitter for? let me guess your foreman is an old school mechanic and he is against efi? no offence intended to you or your boss.
i want to supercharge my lwb one day, but it will be a vitara 16v donk and running efi, its different and is plausable. why not run a supercharger and efi, it is still relatively undone and would be way cool.
luke

[MacDaddy]

eldo wrote:

i want to supercharge my lwb one day, but it will be a vitara 16v donk and running efi, its different and is plausable. why not run a supercharger and efi, it is still relatively undone and would be way cool.
luke

Yep i would go the Supercharger option over the Turbo option any day !

[2stroker]

My lj50 carbie can run upside down...................

sierra carbies are so simple that NOONE can get them to run properly........

it's a Japanese conspiracy...............