Discussion , Boost N' Carbs - Blow & Draw Thru Turbo / Supercharging

[colinnicholson86]

has anyone tried to turbo a stock carb? I realise that it might not be as efficient or logical as turbo efi but i want to be different. it is actually for a F20A carb engine, but the carb is the same as the A20A.
Can anyone please give me some info, suggestions because i am planning to to do this as a DIY project.

[A20A1]

How same is the 4th gen F20A carb? all the same emissions or other vacuum ports? I was hoping that wouldn't be the case. Please get detailed pics if you can... even of the intake manifold.

[colinnicholson86]

Thanks A20A1
Well i live in New Zealand, so they come standard w/o emmissions control. ya it is the same - all the same ports.
How much pressure can the float handle? (wont that be fuel pressure) cause im planning to run an injector above the carb for extra fuel. I am really keen to use the stock carb.
As for a pic all ive got at the mo is this it only shows the intake thou sorry.
http://www.cardomain.com/memberpage/325443/2

[colinnicholson86]

Here i found a diagram of exactly what its like, try this, and go to page 6-12. http://www.honda.co.uk/owner/AccordManual/420/6-6.pdf

[A20A1]

ahh... damn 56k... I'll download it some other time.

[Oyvind Ryeng]

It is also possible to have the turbo suck the air trough the carburettor, like the oh-so-old BMW 2002 Turbo. But you can't have an intercooler with that setup, because the fuel would condense in the intercooler, get stuck, and form large drops. Imagine having a drain-plug in the intercooler. There are some people in Norway running this kind of setup, but the boostlag is insane, and they have to use like 7:1 compression and run water-injetion-systems to keep the knocking away. This is ofcourse a bad solution to turboing a car with carburettor. There are people running carburetted turbocars with the turbo pushing the air trough the carburettor, but they have changed to eiter Detollero (?) or Weber carburettors.

[A20A1]

Yeah it sounds like he was considering the draw thru turbo setup... When I was saying the float was going to break I was refering to a push tru setup.

[colinnicholson86]

I was actually meaning push through. are you able to list the advantages/disadvantages of this setup

[A20A1]

Hrm, I saw some vacuum tubes and such... again no moving parts... couple that with a check valve that uses pressure to seal the valve... and you got something to work with.
I found this nice, and quite large check valve... something I've been looking for, for a possible draw through turbo carb setup... It was the bypass sytem to let the large amount of vacuum created by the closing of the thottle to be seen by the throttle plates and not put some much stress on the oil seals of the turbo.
http://www.anver.com/document/vacuum...arge-check.htm

Problem is any leakage will cause the Air Fuel charge to be diverted back towards the plenum below the carb... possibly wreaking havok with the A/F ratio.

CARB DRAW THRU TURBO

CARB BLOW THRU TURBO

RETURN TO THE TURBO FAQ

[A20A1]

Okay this is basicly a simple research project untill I get the money to develop it.

Please read thru the Turbo FAQ which lists a number of engine management and turbocharging factors I have found on the net. I will continue to update that thread and this one as I find more.
TURBO FAQ

Also for indepth ignition questions
IGNITION FAQ

If you're here to preach Push / Blow - Thru Turbo this isn't the place, I've done the research and know about the downside of draw thru and the potential of Blow thru, this isn't the reason for making this thread. This is simply going to give you insite on how to setup your own Draw-Thru Turbo Carb if that is the way you choose to go.
Turbocharging Carburetor

If you have information you wish to add to the Turbo FAQ specific to the Carb Turbo setup Blow or Draw Thru then please add it to the thread linked below.
FAQ ADDITIONS

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[Civvy]

We could also do it electrically, if we could rig an such a thing as a adjustable solenoid? to move the rod. and maybe some sort of pressure sensor in the charge pipes to trigger the solenoid. Hey thats a good idea! ,,,If we turn into boffins we could develop a pressure sensor that detects how much pressure at a given point and then a solenoid that only retards as far as the sensor tells it to!

[eightyfivelude]

can't you just run a MSD6a box with a Timing Retard controller for boost applications?

Matt

[Civvy]

I guess camshaft TDC is the only way! and maybe..can u set a static timing with a breakerless ignition if needed??

I am i right in thinking people think crank fired ignitions are the best? if so why do manufacturers run the dizzy on the camshafts??

Have you looked at many of the old cars with turbo's they must have similar setups to our thinking since the chip and electonic ignition hasnt always been around!

[A20A1]

Hey check this out !!!

http://www.ele.tut.fi/~vvieri/edstr.htm

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[AccordEpicenter]

guys you can get an msd boost timing master part 5462 to get your boost retard for less than $100 off ebay or some shit

[A20A1]

What about advance? Do we leave the mechanical advance in place or can we lock it?

I know there was a kit right to use MSD with digital advance?


What about a Crane Setup

- Crane 8mm / 8.5mm / 11mm wires
- Crane HI-6TRC Ignition Kit w/ Timing Retard Control

- TRC-2 Timing Retard Control
- 2 Bar MAP Sensor

[Civvy]

Hey check this out !!!
http://www.ele.tut.fi/~vvieri/edstr.htm
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HA,ha! Lovin it..lovin it! Hey! maybe u and i should publish a 'turbo's for tightwads'!!!?
i wish he had a conclusion!
...made a point to me tho!!....if something goes wrong with this i.e. the advance plate sticks, then the earliest warning of the timing not retarding under boost will be a big bang???

Looks good! Jst wondering if your overly concerned, the vacuum of those engines twice and 3 times the size of ours will be more to worry about?
Doesn't a dump valve work on similar principles as u want it to for this?
mmm. are we gona extend the delay in throttle closure? i'm going crosseye'd on this one!!!

[Vanilla Sky]

man, you're doing a lot of research, man...

just curious... have you decided what carb you're gonna use for this? i think if i were gonna do this i would go with DCOEs...

i'm just amazed that someone will put this much research into sometihng like this...

you have my vote for king of 3geez... too bad you don't vote for the king

[A20A1]

Thanks... I just wish I had money to fool with... I still think my engine management might include a J&S safegaurd... http://www.jandssafeguard.com/
Seems easy enough to install.

[A20A1]

I will need a MAP (manifold air pressure) sensor, which will be fitted right before the 3" goes into 4 runners. But what about boost controlling? How would I go about getting a constant 4 psi all throughout the power band?

The PSI is based on the pully ratios... as RPMs go up you may be adding PSI but it's kept in check by the increased demand. You could vent excess pressure but you'll be venting air and fuel which could ignite.

Fuel PSI needs to be 5.5 to 6psi constant under any amount of load

Make sure the fuel hard line is big enough... you should upgrade the stock fuel line to something a little larger. When you replace the fuel hard line I would add about 3" extra to where it pops out of the firewall to make it easier to replace the rubber fuel line.

DeMon carbs are very tunable but are quite expensive... I'd would say 500 CFM is good... I've seen 500 CFM on civics with 1.6 and 1.8 liter forced induction motors.

For ignition management I've looked at the J&S Safeguard... to me the claims it makes suggests it's a good buy.

as for manifold cooling... if the manifold is aluminum you could weld on a circular bar cut in half to make a "U" and weld it under each runner... the stock intake manifold uses coolant partly to keep the manifold at a certain temp... but if you don't live in cold weather it's better to bypass the manifold coolant.

Make sure your ignition system can handle the extra juice it needs to put out to fire the gap under boost... and gap the plugs right so the spark can fire.

One of the highest coil outputs I've found is listed in the ignition FAQ
"MALLORY HIGH RPM PRO MASTER COIL"

Some say irridium and platinum are good cause they can handle the extra heat / stress under boost... but also they increase resistance.
So tthey may turn out to be more of a drawback then benificial.

I don't see much more you need to do then get a properly sized blower and carb.







If you go turbo draw thru Read the turbo FAQ I made... it lists most of the drawbacks and problems with draw thru turbo.
FORCED INDUCTION FAQ
POST #5 IN THE FORCED INDUCTION FAQ DISCUSSING CARB TURBO

I note in the FAQ that you should have some heat to the carb to keep it from freezing on a draw thru turbo setup.

You couldn't run a front mount IC anyways with draw thru turbo because the fuel will seperate form the air.

I looked at the possibilities and I keep falling back on supercharging since it's easier to do with carbs.

Unless you do blow thru carbs... but if you're going that route you might as well go EFI cause you'll make more power and it will be less of a hastle... most carb blow thru setups I've seen rely on secondary injectors for enrichment... so that right there funks the whole reason for going carbed IMO.
Carbs just aren't ment to see pressure, and the added layer of injectors and fuel management just doesn't make it worth the effort.

[Doward]

Just curious if anyone's running a blow-through Weber Downdraft setup. *IF* I go the turbo route, I can just pressurize the carb, provided BOV, rising rate fuel pressure, etc (the standard carb turbo affair), correct? The air emulsion tubes have me slightly worried, but with the fuel bowl under the same pressure as the tubes, I shouldn't be worrying, as long as the entire carb is pressurized, yes?

[POS carb]

my weber doesn't have any emulsion tubes, it's a simple jet/power valve system like Holleys, it also has an air correction jet that kind of acts like an emulsion tube but a lot simpler.

If you can keep the fuel pressure in check I don't thing you will have any problems boosting the Weber (unless you are looking for 20+ psi or something). You may need a checkvalve on the distributor though.

[Doward]

6psi. 8psi at the MOST.

[A20A1]

It doesn't? are you sure? the emulsion tubes are stuck in the holes under the air correction jets... or did you buy a different 32/36 then the one I gave you?

[POS carb]

no I still have the one you gave me but it's all jacked up I haven't taken it apart anymore for fear of it breaking more

The floats broke (JBWELDED) the a/f screw hole is semi-stripped, the throttle shafts leak, the bass makes the tophat and accel pump screws come loose all the time (locktite for now so far so good)
I've been holding onto it until I can figure out how to make the bores bigger or get a 38/38 or figure out how to adapt the Nikki 4bbl to it.