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turbo setup with stock su carbs


erichwaslike

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i dont care how practical... i just want to do it. i want my intake to be stock other than wat is in front of it, just think it wood be cool. and i dont see much for the other carbs on the r16 motors

 

 

exactly why were gettin some discussion action goin on.

 

theres almost no info on it and Iv never visually seen a set up being run (only heard about it), so lets figure out how you can.

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http://www.ximphony.org/moron.html

http://normandy-mini-team.forumactif.net/t91-vds-carburateur-hif-44-turbo

http://cgi.ebay.com....3#ht_500wt_1156

 

 

I researched a couple of different su turbo options, the mg,mini,Austin guys have been using the plenum's from the mg metro, coupled with su Hif44 carbs. I was thinking of doing it on my z only problem was routing the pipping, i thought maybe merging the plenums or just playing with the pipping from the plenums.

 

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so what if you put a check valve on the inboard side if the pot on the carb that only lets vacuum through, then drill new passage on outboard side of pot with checkvelve that only lets boost through, you would also have to push the slide up with boost, where vacuum pulls it up...

 

su%20carb.jpg

edit: if this image is correct, then the boost hole is there as "atmospheric inlet", just leave it open... then for ppushing up on the slide, check valve one "vacuum passage" that only lets vacuum through, then check valve on top of the slide going to atmosphere that will only let air out (need this to let trapped air escape "suction chamber" when pushing the slide with boost)

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  • 1 month later...

Hey guys,

 

So I recently did a KA24E swap into my 510. But I decided to build my own intake manifold and run a set of l24 SU carbs.

 

http://community.ratsun.net/topic/30773-su-carbed-ka24e-finally-running/page__st__40

 

This is the thread. The car runs great and all, but I know Im going to be urking to boost it soon, as I had one of these boosted on my 240sx and it was tits.

 

I was curious as if you guys have figured this out? I would very much like to run blow through, as I feel weird a turbo sucking in gobs of fuel hehe.

 

Anyways any ideas would be awesome, I don't plan on doing this until sometime in the beginning of July :). If your wondering I just plan on running 8 to 10 psi, depending on how tunable this setup becomes.

 

What Im also hoping for is retaining the stock advance vacuum source on the SU, and hope that will solve my timing issues? if not I can go the MSD route no problem since Im running a petronix.

 

Although with a proper IC setup and good fuel the stock timing on the KA upto 10PSI should be good anyways.

 

Anyways any ideas and suggestions are super welcome :)

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How about just running a full flow type setup? Make a port on the carbs fuel bowl at the level you dont want it to pass and use it as a return line so the fuel flows through the bowl constantly, and what ever the engine doesnt need will be returned to the tank through the extra port instead of fludding the engine, and then under boost, instead of returning most of the extra fuel to the tank, it will take what it needs.........Just an idea, not sure if it will actually work properly.

 

Another thing you can do, and we have done it many times in the past on Turbocharged aircooled VWs is run a good high pressure fuel pump along with a boost sensative fuel presure regulator. Set the fuel pressure to whatever the SU carb needs that way it runs properly off boost, and when under boost, the regulator will sense boost and will send higher pressure of fuel through the carb which will make it get past the needles and flow more fuel as needed according to the boost that the regulator sences. We even modify our own regulators sometimes to make them boost sensative if they arn't already. Its pretty simple.

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Remember the TV show "The Avengers"? John Steed drove a Bently. The Bently Blower version had 2 SU carbs before the supercharger mounted on the front of the car and driven from the crankshaft. Looks to me like the old timer Brits figured out where the SUs should go many years ago. Suck through.

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Looks to me like the old timer Brits figured out where the SUs should go many years ago. Suck through.

 

 

if you had read threw the thread we already know that, but thats not the point of this thread.

 

 

draw threw set up already is documented and works were well aware.

the point of this thread was to try and figure out how a blow threw set up works with SU's not what the best set up is

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How about just running a full flow type setup? Make a port on the carbs fuel bowl at the level you dont want it to pass and use it as a return line so the fuel flows through the bowl constantly, and what ever the engine doesnt need will be returned to the tank through the extra port instead of fludding the engine, and then under boost, instead of returning most of the extra fuel to the tank, it will take what it needs.........Just an idea, not sure if it will actually work properly.

 

Another thing you can do, and we have done it many times in the past on Turbocharged aircooled VWs is run a good high pressure fuel pump along with a boost sensative fuel presure regulator. Set the fuel pressure to whatever the SU carb needs that way it runs properly off boost, and when under boost, the regulator will sense boost and will send higher pressure of fuel through the carb which will make it get past the needles and flow more fuel as needed according to the boost that the regulator sences. We even modify our own regulators sometimes to make them boost sensative if they arn't already. Its pretty simple.

 

Actually the second idea I like a lot. For the simple reason is that I know it works, because I ran a setup like this on my 1990 240sx with a ka-e, got my self a 1:1 rising fuel pressure regulator. And up to 8psi on stock injectors with a nice walbro fuel pump, it ran 8psi all day long :). So Im sure with these 44mm SU's, Il be able to deliver fuel way passed 8psi no problem. Of course I only plan on running the GT28r :)

 

I guess I just really wanted to build a cool plenum for my SU's and call it a day hehe.

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Looks to me like the old timer Brits figured out where the SUs should go many years ago. Suck through.

 

well shit theres our answer... i wish someone wood have said that pages ago then we would be done. now for the ppl that have read the whole thread and know that draw thru isnt the focus or even allowed to be mentioned again or ill find a way to ban u... any one figure out how to get the slides to operate properly? from my understanding its the vacuum from the motor pulling fuel into the intake that forces them open, but i cood be wrong, and with boost in front of them it wood make them not want to open... right? since they have the butterfly cood the slides be taken out or do they serve a purpose like adding more fuel or something

 

 

 

wtf do the slides do dammit?

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  • 8 months later...

well shit theres our answer... i wish someone wood have said that pages ago then we would be done. now for the ppl that have read the whole thread and know that draw thru isnt the focus or even allowed to be mentioned again or ill find a way to ban u... any one figure out how to get the slides to operate properly? from my understanding its the vacuum from the motor pulling fuel into the intake that forces them open, but i cood be wrong, and with boost in front of them it wood make them not want to open... right? since they have the butterfly cood the slides be taken out or do they serve a purpose like adding more fuel or something

 

 

 

wtf do the slides do dammit?

 

The slides meter the fuel to the motor. From my understanding, they work on a pressure differential. So therefore should work under boost. As long as the outside of the slide sees a higher pressure than the inside of the slide, it should work.

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  • 3 months later...

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