You can find those airboxes everywhere they sell webber or mikuni carbs. All the vw aircooled places have them in orange county you see the turbo hats on all the aircooled vw bug engined in the dunes. Try local dunebuggy stores with high performance parts I've seen them for 120$ for both bonnets. The first civic I saw break into the 13's had them on his car back in the late 80's/early 90's and ran a blow thru system.
From Härkölä Jukka, a guy that has a blow through setup with a Dellorto DHLA (very much like the Weber DCOE) on a Mini. I found him on the Yahoo blow-through turbo forum (http://autos.groups.yahoo.com/group/blowthruturbo) and I've been emailing with him. Check out his webpage: www.geocities.com/jharkola/1380turbo4.html
Sweet info!Most local "experts" have said that the trick is to use relatively small choke to get any kind of drivability. I started with 36 mm chokes, then 34 mm and finally 32 mm chokes. Note that the engine size in my Mini is 1380 cc and usually it uses either 36 mm or 38 mm chokes in n/a street engines and 38 mm or 40 mm in serious race engines.
With larger chokes the hig speed mixture could be made rich enough but the transition from idle jet to main jet was just a big hole. Anothe emulsion tube fixed the transition but then there was no fuel under boost... Going to smaller chokes did help the drivability enormously but did not cure it completely.
Now, the real trick was to locate a book called "Turbomania" by Bob Tomlinson. A guy called Dan Noble in San Diego USA hinted about the book that contains a load of info about turbo VWs. Located and bought. The trick here is to use a restriction at the carb mouth, like a stub stack but with a bore smaller than the carb bore. Judging by the jetting info supplied it seems that the size of the restriction is about the size of the choke or even less. So I turned a pair of inserts with 34 mm ID for my stub stacks and refitted the 34 mm chokes. Well you know the old wisdom: only change one thing at a time...
Now the engine works just as well with the 34 mm chokes + restrictions as with 32 mm chokes. It would probably be better with even smaller ID restrictions. By making the carb pressure sensitive it has made the jetting a bit easier. Still the jet sizes look a bit large compared to choke size but smaller simply will not work... Still the jetting is not perfect: there is a spot at about 2500 rpm where the engine hesitates: depending on the idle jet holder vs. emulsion tube combo it´s either rich or lean. But with WOT it runs very nice. I would like the engine to run smoothly from idle to max rev on 4th gear. Now it stumbles at about the said 2500 rpm. Actually no big deal once you know it is happening, simply go to 3rd gear and hit it.
I have experience only with Dellorto carbs but similar approach can possibly be adapted to DCOE range. Dellorto turbo carbs had seals on throttle shafts plus rubber 0-rings for idle screws. All drilling plugs had been sealed with lacquer. The gaskets were made of rubber.
A couple of years ago I did phone around about DCOE suitability and was informed that 151 and especially 152 type Webers were suitable for blow thru out of the box.
Mike Clark
sorry to get off topic, but for a 32/36 this is a pretty good picture of what you would need to build. it's a pressurized box that encases the whole carb. it's on a V-8, and it's a supercharger, but you get the idea. i have this issue at home somewhere and if anybody wants i can scan it when i go home this weekend. i only have a yahoo email though so i don't really have a way to send it to anybody. i couldn't shrink it down enough to where it would be sendable through yahoo and still readable. sorry to interupt. ironic cover though.
-Grant. I'm just a pirate chasing booty.
I'm probably looking at a supercharger instead of a turbo... the custom header work and intercooler custom setup is going to cost a bundle. With a centrifugal (not root) supercharger, I could run the same type of blow-through setup. How would the timing work, though? On a carb'd a20, the timing is retarded quite a bit from the efi one... and on an efi setup, I'd advance the total timing 16-20 degrees (depending on a lot of things)... how would you know how to prevent detonation with this? Besides rods and seals and pistons and the usual... I mean as far as timing goes. Trial and error?
I'm real interested in running 45 DCOE's for this, and a blow-through supercharger... that'd be amazing. A turbo is just too much work (though I LOVE the whine, and the blowoff sound... ugh..)
hit back
bury the bach.
http://home.stny.rr.com/versanick/burythetach
bump... I hate having to search for this thread, anyways I'm adding you, SIte to the turbo thread under "in the works"
- llia
Sooo what happened? u got any further? I'm only used to keihen's and i should proly just shut up and listen and not ask questions but hell with it...help me understand something.
If hyperthetically we were to use the stock carb and it didn't leak.we just put a hat on the top.we made the secondary really rich and went back to being vacum controlled but from the boost guage pipe....so we get a normal running car using the primary then boost plus extra fuel on the secondary. Then those fuel vents can we not use rubber pipes and have them outside of the hat using no pressure? = thus not crushing floats etc.
only setup that won't crush the float is a draw thru...
the float bowl and the inlet to the barrels are all connected.... you'd have to make some pretty tight seals to ceep the float from seeing pressure... but you'd still need to up the pressure of the fuel... soo you'll probably end up breaking the float anyways or at least busting the O-rings on the float valve itself.
- llia
If you must know here was my plan to turbo a carb...
https://www.3geez.com/showpost.php?p=440731&postcount=5
taken from the FAQ
https://www.3geez.com/showthread.php?t=37169
Last edited by A20A1; 09-19-2004 at 05:09 PM.
- llia
It doesn't mention the vacum problem u get when the butterfly has just closed and the turbo is still trying to boost and the weight of the fuel on the compressor fins.
I like the idea's that (hawaii.com) lude did running twin 40's. He ran 16psi boost thru that motor with most of the engine as stock and managed low 12's. I'm gonna run the B20 with 45's/total seals/forged pistons/p+p head/spun flywheel/crank and not to forget a better looking header than his! he,he
with the B20 i can have better valve timing using 2 adj pulleys as opposed to 1! ....11's? and should compensate for that issue they had having to go smaller in intake size...(mini)?
Seriously, we should bitch all these concerns out and that way it'll point us in the right direction with using carbs. I cant wait to hear what robs runs at!
Last edited by Civvy; 09-20-2004 at 05:39 PM.
did anyone actually look at the hawaii guys setup? He is usinga blow through weber setup mated to a a20 fuel injected manifold. The injectors are there to add the extra fuel the engine needs while under boost. Ingenius seupt if you ask me
Matt
1985 Honda Prelude SOHC ET-2
Civvy I read about those 2 very issues and added them in to the FAQ where I'm discussing the draw-thru setup.
I'm going to use the injector ports for water / alcohol injection... sure it's a pain to carry around an extra resivoir... but it's the only alternative since an intercooler isn't possible.
Plus I read that richening the mixture to prevent detonation isn't the best way and only works up to a point.
I also read that water injection will allow for less retard on the ignition.
- llia
eat your heart out. i have been studing this for about a week nowa nd came donw to that i will need a inline beefy fuel pump, and a beefy fuelpreasure regulater with 2 ports for each weber like you said. also the thing that is holding me back is the turbo exhaust manifold. i woudl need to build one. along with the piping adn the airbox. auctualyl this project is very doable for under 1200 bucks.
-1986 Honda Prelude DX:
pacesetter cat back w/Magnaflow muffler
lightspeed header
ngk iridium plugs
Pacesetter short shifter
94' integra coilovers
k&n oil filter
i'd say a blow-through would work better or maybe be easier, i read somewhere that the webers can take a considerable amout of boost(for our cars) out of the box. or you can have weber rebuild them for use witha turbo up to over 20lbs i think.
Actually the draw thru will be easier since it requires less fuel management... but isn't the best for making the most power in a more efficient manner.
I'm going for a low boost though, just to know that what I'll be using works together ie: the water injection and turbo Charge pipe routing and efi manifold and long wrapped turbo header tubes.
Plus I'd need a turbo cam...
One thing I hate about all this is carrying the water resivoir... one reason why I'm still a big supporter of N/A
But the technical challenge of turbocharging is right up my alley.
- llia
I added even more info. take a look
https://www.3geez.com/showpost.php?p=440731&postcount=5
I'm a bit concerned about the oil issue...
I'm sure I can make a manifold more acceptable for a carrying the air fuel charge... the problem is at the turbine...
What drives me nuts is that the turbo is hot so the fuel would vaporize right and thus be less affected by the turbine then what most people are trying to suggest.
Last edited by A20A1; 09-21-2004 at 01:39 AM.
- llia
ACCORD 3G RUNS FOR EVER
Yeah I live in Hawaii,
If I closed off the stock keihin manifold like the guy with the Nissan did... and had the turbo in the same spot in relation to the manifold it might end up being better to route the turbo pipe from the head, under the pan and back up top the turbo... that way I have the shortest possible connection between the turbo and the carb wet-flow manifold... I have a short version of the carb manifold but I'd still need to split the air/fuel mixture.
Last edited by A20A1; 09-21-2004 at 04:32 AM.
- llia
I have alway sbeen confused about turbo and the carb. I dont understand why this ouwldnt work the same way as an efi Just add the manifold and and the turbo and run the piping like the carb was the TB.
You guys dont have to explain I was just saying..Showing my ignorance
"I'll head back to the neverland ranch with a peanut butter jelly chiken tuna sandwhich.."
well, oil is just a case of longer pipes usually but, i dont think an oil cooler is gona cool it to the extent that it gets thicker again! also, it would then be heavier - so theres one loss. that manifold sprung the a18 carbs 2 mind!!!? ...we could use them for their butterflys only? ...why is an intecooler out? dont 4get the scoobies!! they're directly above your setup. whats this turbo cam? ...thats crap! i'm more for thr su design mike as a drawthru..thoose are sooo easy to tune. Still concerned about heat on that setup tho...its bad enough on the common design. i know ure always up for a challenge but is low (hot) boost really worth all? I have alwys been fond of the N/A specialy the u.s. muscle sound, and i defo will NOT be getting a noisy dump valve. I'm in steady competition with a N/A drag driver so i've descided i cant go the same route to beat him ...thats not competition, and it gets boring to quick
ther are a LOT of issues that come up with turbo's and carbs. Carbs work by vacuum and air pressure and that all changes 10fold when you hook up a turbo to a carb. Its been done a lot, but its significantly harder to rig up then with fuel injection.Originally Posted by unc25
Nothin' 2 Old Racing
yea i ment to psot that link in my reply but forgot it!
-1986 Honda Prelude DX:
pacesetter cat back w/Magnaflow muffler
lightspeed header
ngk iridium plugs
Pacesetter short shifter
94' integra coilovers
k&n oil filter
Turbo cam, something with less overlap... and a delayed intake opening to combat reversion...
I need one because I have a wild N/A grind now that has way too mush overlap to run turbo.
Forget easy to tune.... SU carbs aren't sexy... or at least not the ones I've seen...
I want a 4bbl (Demon, hehehe) or something with a stack or fitler on top... I'd hate to build goofy carb hat or cover the carb up completely in a box... that just doesn't sit right with me.
Fuel would get caught up in the intercooler and seperate from the air... it's not a wet flow design and I haven't seen any wet flow intecoolers. I had stated that as the problem... in the FAQ.
I woudln't worry about the pumping losses of heavier oil if it ment the turbo was safer.
Sure gains will be minimal without water injection, but with water injection boost can be increased.
I'm trying to find an article written by TURBO TOM
they say he's done plenty of work with draw thru and other turbo setups and prefers draw thru.
- llia
Sweet!
http://www.bryanf.com/510/e3.htm
390 dbl pumper.
rotary
oldschool datsun
yellow and black
- llia
Since its a very much triall and error project i'm gona use cheap stock cams for now.
We used twin S.U's on a friends MG Mini turbo and the only tuning methods were simply Spring/jet/needle ...wasn't so hard!
As i said there'll be nothing goofy about my tophat it will have inertia in mind when its getting designed, unlike the many i've seen...so far!
With the oldskool drawthru method it has its several drawbacks i.e. poor economy/throttle response....and i'd hate that!!
The S.U's and maybe the prelude a18 carbs could be dual or 4's and wouldnt be too hard to fit the stock mani maybe??..i know we can get the linkages for quad su's from the old triumps and ?honda 800?? These along with the Webers are particulary good for both setups..in fact most if not any carbs could be used!!?
As for floats i've got a few idea's i could use thin piping from a hobby shop and have them each side of the float...this will prevent collapse. Fill them 'proportunatly' with spray foam. use solid plastic one's...hey, sometimes u can get away with stock floats under low boost!
What about using the f.i. flange on the modded stock mani if your gona use an f.i booster, it'd also give u ports for injectors! and in the best place.
Looks like thats what the Hawaii Lude did too!
I've got to add at this point... The fastest road car in the U.K. is indeed an MG Maestro 2.0L Turbo! The car is now F.I. but, originally was using the push-through method via a single S.U. carb! and was then still the fastest hot hatch in the country! 0 - 60mph in less than 60secs! and also note this car is a 4door hatch
Last edited by Civvy; 09-22-2004 at 12:11 PM.
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