Blow through IDA?
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Rollin' coal and 53mpg!
Joined: Oct 2002
Posts: 1,126
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From: Jacksonville, Floriduh
Blow through IDA?
I need to know what all is necessary to convert my Weber 48IDA to a blow-through setup.
As much as I'd love to send my carb off to Robert, I'd like to learn how to do it myself. So if someone can tell me what all I need, and jet sizes , etc.
BTW, it's a stock port 12a, and I'll be using a S5 turbo.
As much as I'd love to send my carb off to Robert, I'd like to learn how to do it myself. So if someone can tell me what all I need, and jet sizes , etc.
BTW, it's a stock port 12a, and I'll be using a S5 turbo.
Following info was found on a search. I know it was there cause I originally asked the question.
on a stock motor with a small turbo i would go with
Venturi- size..... 36 or 38 mm
Fuel Jet- # .......180
air jet- #.............160
Emulsion tube.......F11 or F16
needle Valve- #...........300
also on IDA carbs the floats are brass so you need to drill a small hole and fill it with that expanding foam, then solder up the hole. if you don't do this the float will crush with boost..
I have a 300 needle seat if your interested pm me, really damn hard to find
on a stock motor with a small turbo i would go with
Venturi- size..... 36 or 38 mm
Fuel Jet- # .......180
air jet- #.............160
Emulsion tube.......F11 or F16
needle Valve- #...........300
also on IDA carbs the floats are brass so you need to drill a small hole and fill it with that expanding foam, then solder up the hole. if you don't do this the float will crush with boost..
I have a 300 needle seat if your interested pm me, really damn hard to find
Joined: Mar 2001
Posts: 31,819
Likes: 3,223
From: https://www2.mazda.com/en/100th/
its going to be a little tricky to get the jetting to be good under boost AND cruise, but you WILL need a 3.0 needle and seat OR a gross jet (mazdatrix sells em)
i have no jetting reccomendations, but the idle should be about like any other IDA, so a 55-65 jet should be good.
the main jet depends on how much boost and what AFR you want to run....
the air corrector and E tube, are the tricky parts, as they control the transition of the main circuit, and i'm really not sure what a turbo car would want. the MFR combo of F8 e tube + 130 air jet has the main circuit coming on at a really low RPM, and it actually had a rich stumble.
i've never tried the F11's, but i think the main circuit would come on too slow to even run on the P port, but of course the turbo is different....
oh and i'm running a P port, but its corked up, its starts pulling hard about 2500 and gets better til about 6k. i'm around 200hp @6500rpms, which is in the ballpark of a 12A/stock turbo @10psi, i think.
i'm running 60 idle jet, 100 idle jet holder, gives 14.4AFR from idle to 2500rpms
fuel pressure is unregulated from the carter, it puts out 4.3psi with the key on engine off, but its probably more with the engine running. if i dropped fuel pressure i think i'd need more jet, and if i uncorked the motor it will need more jet...
main jet is 175, which gives me mid 11's, my fuel pressure is high though, and its corked up.
air is 140. 130 causes a rich stumble@2500, 150 causes a lean stumble @2500
e tube is F8.
43mm venturis, not sure how this affects the rest of the jetting, i have 38's but i have no reason to swap em, it pulls like a truck!
float level is as high as it can go without leaking thru the boosters
3.0 gross jet
anyways, i went thru each part on the carb, starting with the idle, and working my way up, and i have a little journal, and i know what piece does what, so making changes are really simple now, no guesswork...
i have no jetting reccomendations, but the idle should be about like any other IDA, so a 55-65 jet should be good.
the main jet depends on how much boost and what AFR you want to run....
the air corrector and E tube, are the tricky parts, as they control the transition of the main circuit, and i'm really not sure what a turbo car would want. the MFR combo of F8 e tube + 130 air jet has the main circuit coming on at a really low RPM, and it actually had a rich stumble.
i've never tried the F11's, but i think the main circuit would come on too slow to even run on the P port, but of course the turbo is different....
oh and i'm running a P port, but its corked up, its starts pulling hard about 2500 and gets better til about 6k. i'm around 200hp @6500rpms, which is in the ballpark of a 12A/stock turbo @10psi, i think.
i'm running 60 idle jet, 100 idle jet holder, gives 14.4AFR from idle to 2500rpms
fuel pressure is unregulated from the carter, it puts out 4.3psi with the key on engine off, but its probably more with the engine running. if i dropped fuel pressure i think i'd need more jet, and if i uncorked the motor it will need more jet...
main jet is 175, which gives me mid 11's, my fuel pressure is high though, and its corked up.
air is 140. 130 causes a rich stumble@2500, 150 causes a lean stumble @2500
e tube is F8.
43mm venturis, not sure how this affects the rest of the jetting, i have 38's but i have no reason to swap em, it pulls like a truck!
float level is as high as it can go without leaking thru the boosters
3.0 gross jet
anyways, i went thru each part on the carb, starting with the idle, and working my way up, and i have a little journal, and i know what piece does what, so making changes are really simple now, no guesswork...
Joined: Jul 2002
Posts: 7,301
Likes: 3
From: District of Columbia
FYI, You HAVE to replace the floats in an IDA with neoprean floats. The brass floats will crush at about 4psi. And, Robert is the only source in the US for them.
Joined: Jul 2002
Posts: 7,301
Likes: 3
From: District of Columbia
I've done a few blowthrough setups. The ionfo above might get it driving, but you'll msotlikely want to run richer. I am an avid supporter of getting people to stop usinf F-11 e-tubes. They are just too lean and make you need 200+ main jets and <130 air correctors to even get close to the fuel required at 7k rpm under 10 lbs of boost. Read up on my carb tuning and emulsion tube thread. There is some great info in there that I aquired over years of tearing my hair out, I mean weber tuning.
edit: Oh snap! This is an OOOLLLDD thread 2004!
edit: Oh snap! This is an OOOLLLDD thread 2004!
Trending Topics
its going to be a little tricky to get the jetting to be good under boost AND cruise, but you WILL need a 3.0 needle and seat OR a gross jet (mazdatrix sells em)
i have no jetting reccomendations, but the idle should be about like any other IDA, so a 55-65 jet should be good.
the main jet depends on how much boost and what AFR you want to run....
the air corrector and E tube, are the tricky parts, as they control the transition of the main circuit, and i'm really not sure what a turbo car would want. the MFR combo of F8 e tube + 130 air jet has the main circuit coming on at a really low RPM, and it actually had a rich stumble.
i've never tried the F11's, but i think the main circuit would come on too slow to even run on the P port, but of course the turbo is different....
oh and i'm running a P port, but its corked up, its starts pulling hard about 2500 and gets better til about 6k. i'm around 200hp @6500rpms, which is in the ballpark of a 12A/stock turbo @10psi, i think.
i'm running 60 idle jet, 100 idle jet holder, gives 14.4AFR from idle to 2500rpms
fuel pressure is unregulated from the carter, it puts out 4.3psi with the key on engine off, but its probably more with the engine running. if i dropped fuel pressure i think i'd need more jet, and if i uncorked the motor it will need more jet...
main jet is 175, which gives me mid 11's, my fuel pressure is high though, and its corked up.
air is 140. 130 causes a rich stumble@2500, 150 causes a lean stumble @2500
e tube is F8.
43mm venturis, not sure how this affects the rest of the jetting, i have 38's but i have no reason to swap em, it pulls like a truck!
float level is as high as it can go without leaking thru the boosters
3.0 gross jet
anyways, i went thru each part on the carb, starting with the idle, and working my way up, and i have a little journal, and i know what piece does what, so making changes are really simple now, no guesswork...
i have no jetting reccomendations, but the idle should be about like any other IDA, so a 55-65 jet should be good.
the main jet depends on how much boost and what AFR you want to run....
the air corrector and E tube, are the tricky parts, as they control the transition of the main circuit, and i'm really not sure what a turbo car would want. the MFR combo of F8 e tube + 130 air jet has the main circuit coming on at a really low RPM, and it actually had a rich stumble.
i've never tried the F11's, but i think the main circuit would come on too slow to even run on the P port, but of course the turbo is different....
oh and i'm running a P port, but its corked up, its starts pulling hard about 2500 and gets better til about 6k. i'm around 200hp @6500rpms, which is in the ballpark of a 12A/stock turbo @10psi, i think.
i'm running 60 idle jet, 100 idle jet holder, gives 14.4AFR from idle to 2500rpms
fuel pressure is unregulated from the carter, it puts out 4.3psi with the key on engine off, but its probably more with the engine running. if i dropped fuel pressure i think i'd need more jet, and if i uncorked the motor it will need more jet...
main jet is 175, which gives me mid 11's, my fuel pressure is high though, and its corked up.
air is 140. 130 causes a rich stumble@2500, 150 causes a lean stumble @2500
e tube is F8.
43mm venturis, not sure how this affects the rest of the jetting, i have 38's but i have no reason to swap em, it pulls like a truck!
float level is as high as it can go without leaking thru the boosters
3.0 gross jet
anyways, i went thru each part on the carb, starting with the idle, and working my way up, and i have a little journal, and i know what piece does what, so making changes are really simple now, no guesswork...
Sorry for the thread jjack.
I agree with running F8's, or even F7's in the IDA for boost prep. I think I'd try big chokes/venturi's first too. Start with a big main jet first, same goes for air jet.
But hey, I honestly hate boost. :P and have no experience with it. Ridiculous porting for me.
Joined: Mar 2001
Posts: 31,819
Likes: 3,223
From: https://www2.mazda.com/en/100th/
me neither, it bugged me for a little while, but i decided that corked up P port and 6psi of fuel pressure (or whatever its running) = 175 jets....
oh AND i'm not sure i trust the wideband 100%, the engine is HAPPY and the plugs come out looking really nice. so i'm actually glad i didn't tune it to some random number i read on the internet
oh AND i'm not sure i trust the wideband 100%, the engine is HAPPY and the plugs come out looking really nice. so i'm actually glad i didn't tune it to some random number i read on the internet
and the 3.2 Glass Ball Needle Valve .
