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Draw-Thru Turbo set-up help.


hiromino

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hi. i went to jank-yard last weekend since all the parts were on sale on that day(50%off!!!). i found turbo ex-manifold, j-pipe and turbo. at that time i didn't know what i waas going to do with that stuff since i have 240z withL24. however, after talking with my friend we ended-up planning L24 Draw-Thru Turbo with Twin-SUs. after we have planned that i went over web looking for some tips. and here is the plan i have. since i am new to turbo and mechanical stuff please help me!

get single weber carb set-up to make it easier(my SUs are late model which could cause a lot of problems), install ex-manifold, j-pipe and turbo. then make a sarge-tank to let the air go thru weber. in addition get turbo fuel pump. this is the plan i have. seems to work for me but, again, since i am new to swap things around i am not confident. please if anyone have done this and know what to do. please help me! i know swap turboL28 and Ecu will be lot easier but this is all i can afford for now!!!!!!! thanx!

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i really dont think it would be cheaper to run draw thru carb system. the old draw thrus are rare, thus they are costly, youre looking at 500.00 just for the manifold. if you can store the car, im sure someone looking to restore a z is going to want that l24 and the trans to make their car numbers matching ish, or you could use your motor and trans as a core at the junkyard and grab a zxt motor and trans for pennies, maybe 2-300 hundred bucks for all and youre set, kinda... gosh, sometimes maybe theyre isnt a cheap way around it icon_confused.gif

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You could always use the 4 barrel Holley manifold and do a blow thru set up. The upgrades for the Holley are off the shelf, so it shouldn't be too hard. Big trick is the boost referenced fuel pressure regulator and making an airbox for the carb...no biggie... icon_biggrin.gif

Tim

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Guest Anonymous

Blow through is much prefered, draw through is a dated technology that is all but dead (according to Corky Bell's book anyway). The problem you face is fuel puddles in the turbine housing (gas falls out of the air fuel mixture), when enough boost is built it blows a big fat rich mixture into the engine, a big bog happens followed by a neck snapping power. Early turbo Kawasaki Z1 motorcycles had a aftermarket kit just like this, it was scary at best, it would blubber and then pick the front wheel up and at 90 mph, thats a bit scary for most people on a bike.

 

Blow through is much more do-able, I'm not sure the SU's would work, as mentioned a modified Holley can work fine, but do understand that due to the limited number of metering circuits the average carb has, your mixture won't be as consistent as a fuely engine. You'll also need to probably control your timing somewhat to taper off the advance curve as the boost comes up, otherwise your going to probably run into detonation if you run very much boost at all (more than 7 psi). In Corky Bell's book he shows a bank of sidedraft webers in a enclosure and they apparently work well with less mods.

 

I have looked into this a bit as I'm interested in mild boost for my V8, and blow through being a bit cheaper suits my budget a bit better. (unless it kills the engine with detonation, then it definitely isn't cheaper).

 

I've looked into Carb enclosures (carb is in a box which pressurized the entire carb, no problem with leaking throttle shafts then from the boost) which seems like a good go, but the ones from Vortech and some of the other supercharger places charge rediculous amounts of money for a cast box and some linkage hardware.

 

If I go this route (money being what it is, not soon probably) I'll construct my own carb enclose and save my self a bunch of money.

 

Well thats the short version of what I've found out so far about blow through applications and what I've read about draw through.

 

Regards,

 

Lone

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I have read on other forums that the mixture leans out at higher rpms/boost, so they put a boost referenced injector in the inlet pipe to the carb's air intake. As for timing advance control, can't that be done by changing the advance curve in the dizzy with different weights and springs?

Tim

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if you can find the BAE turbo kit, you can convert those to carb pretty easy, since they were meant for na l28 aps, some even have bungs for blow off valves, check out zcar of ebay.

WAAAAAAAAAAAAAAGAAAAAAAAAAAAAAAAANAAAAAAAAAAAAMIIIIIIIIIIIIDOOOOOOOOOOOOOOOONNNNNITE! just had to get that off my chest.

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Guest Anonymous

Tim,

 

Yeah, you can use extra injectors check this page out:

 

http://www.geocities.com/MotorCity/Downs/8668/index.htm

 

See the Budget twin turbo section...

 

I asked him about the pressure switch he used, lol, he said he got it from a heating and A/C supply place. It detects pressure and then fires a cold-start injector.

 

You can lock out the distributor from advancing past say 25 deg total advance (I've seen this done with simple screws even to lock the weights and advance mechanism), but a more eloquent way of doing it is to back the advance off as boost rises, MSD has a deal called the BTM (can't recall the number of the product), but its adjustable to turn advance back from like 1-3 deg. per pound of boost.

 

The important bit is to eliminate any chance of detonation and keep it a bit rich and it'll live, otherwise, it'll look like the piston was chewed on by a gorilla.

 

Regards,

 

Lone

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Guest Anonymous

Is there some good 'in depth' sites on turbo/supercharging that anyone knows of Id like to learn a bit more about doing this type of stuff myself, without going to the expense of buying tech books which start at $40-60+ here in Aus.

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Guest Anonymous

Robzilla, these two are specific to VW's and Mustangs and, but both have good information that is applicable. There are lots of others I can give you, mostly though a search in a search engine of Turbo, or Turbocharger will give you most of them.

 

http://www.sn95.com/projects/turbo/part1.htm

 

http://www.dune-buggy.com/turbo/fuelsystem.htm

 

The next few are just some I have put in my favorite URLS under Turbo:

 

http://www.skulte.com/turbo.html <-- Attn SuperDan, this ones a twin turbo TPI!

 

http://www.geocities.com/MotorCity/Garage/1378/

 

http://www.geocities.com/MotorCity/Downs/8668/index.htm

 

Most of these sites have decent info, if you want the technical aspects, look for Maximum boost by Corky Bell or Turbochargers by Hugh Maccines. The last one is a bit dated, but the equations and such are still applicable. Hope this helps..

 

Regards,

 

Lone

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Guest Anonymous

In Corkys book, he mentions Mikuni and Weber side draft as being some of the easiest to modify for Blow thru applications. Unfortunately he didn't elaborate on what mods they need vs the ones I've seen mentioned for the Holleys. icon_mad.gif

 

But... upon re-reading you message (leap before you look lone, good job malebitchslap.gif ) you're speaking of a downdraft carb?

 

Regards,

 

Lone

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Guest Anonymous

Sounds like a good plan. I've used they're downdraft before, nice carb didn't have any problems with it. Some don't like them, but I also liked the Holley/Weber progressive 2 bbl, had one of those on the (putting bag on head) Vega I owned when I was younger. Worked pretty sweet and gave that 2nd bbl kick like a mini 4-bbl. Besides the crappy engine, I liked the vega actually, handled ok for what it was. bonk.gif

 

Regards,

 

Lone

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whoa that was weird,

waaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaannnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggannnnnnnnnnnnnnnnnnnnnnnnnnoo midoniiiiiiiiiiiiiiiiiite!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! (did i do that? twak.gif )

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