single turbo blowin through a carb
11-16-2008, 07:12 PM
#1
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single turbo blowin through a carb ive finally started to get this thing running decent. i recently installed a front mount intercooler and saw a world of difference. hows breakin the tires loose in fourth just by floorin it at 60mph sound? this is a standard holley 850 modified in our garage! its still rich dowm in low rpms i could use some advice on tuning the carb. anyone blowing through a carb too? oh its up to 14 psi boost now lookin to run it at 20-22psi and 700 rwhp
11-16-2008, 08:52 PM
#2
Been there, done that, got the t-shirt, still going to therapy as a result.
Being in a northern climate, I spent more time tuning than having fun with the car.
Here is a copy of the blow through tuning guide.
, repeat as required...LOL
Seriously though,
What exactly have you done to the stock carb?
Does your carb main body have removable air bleeds?
If so, you can open up the idle air bleeds a little to slow down the low speed enrichment.
Also, the power valve channel restrictors should be opened up to at least .080 for 700HP so that you can use a smaller main jet to keep the low load fueling under control.
I had a hard time tuning my tip in fuel after adding the intercooler, but I was Procharged so it was more of an issue.
With a turbo, the airflow at tip in is much easier to tune since it is a more gradual change in air speed and CFM.
Feel free to PM your # to me if you would like to discuss this in detail.
Most importantly, change ONE thing at a time and take good notes of what happened.
Jim
Being in a northern climate, I spent more time tuning than having fun with the car.
Here is a copy of the blow through tuning guide.
, repeat as required...LOLSeriously though,
What exactly have you done to the stock carb?
Does your carb main body have removable air bleeds?
If so, you can open up the idle air bleeds a little to slow down the low speed enrichment.
Also, the power valve channel restrictors should be opened up to at least .080 for 700HP so that you can use a smaller main jet to keep the low load fueling under control.
I had a hard time tuning my tip in fuel after adding the intercooler, but I was Procharged so it was more of an issue.
With a turbo, the airflow at tip in is much easier to tune since it is a more gradual change in air speed and CFM.
Feel free to PM your # to me if you would like to discuss this in detail.
Most importantly, change ONE thing at a time and take good notes of what happened.
Jim
11-16-2008, 09:36 PM
#3
I built a combo like that once. It was a 377 SBC with fastburn heads and a 230/230 cam. Turbo was a T76GTS and the carb was from CSU. It made anywhere from 480 hp at 3.5 psi boost on up to 930 hp (and 1080 ft-lb) at 17 psi boost. And the kicker is that WE NEVER TOUCHED THE CARB. It was perfect right out the box at a broad range of boost levels - unlike my 2 bar SD LT1 that I've been tuning on for years (literally). Then again, if I simply unplug my WBO2, my tuning would have been done long ago.
I guess in south La, it's just hot all the time, so no re-tuning on the carb is required.
Mike
I guess in south La, it's just hot all the time, so no re-tuning on the carb is required.
Mike
11-17-2008, 06:53 AM
#4
knowing what you have done to the carb would help-i have had a bunch of blowthru projects, got them all to run pretty good-one thing i have learned is the LS motors require a diff tune
i have used csu carbs, he's a wealth of tech help if you need to dial it in more
i have modded my own, using the a/b's, pvcr, changing the p/v's closer to engine vacume, jets, pump cams, etc
i will admit, the colder weather will affect it, where FI can adjust more to it, i guess with the MAF or something
i have used csu carbs, he's a wealth of tech help if you need to dial it in more
i have modded my own, using the a/b's, pvcr, changing the p/v's closer to engine vacume, jets, pump cams, etc
i will admit, the colder weather will affect it, where FI can adjust more to it, i guess with the MAF or something
11-18-2008, 04:51 PM
#5
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blow through carb tuning ok so the main wells to the jts aredrilled to.180 and main body does have removable air bleeds but i havent changed them. its a ProForm main body 830cfm. thats all we did to the carb besides play w jets 80s in the front and 93s in the back. its running rich down low before the boost kicks in. it seems good at full boost i dont know for sure until i put on the wideband. thanks for your help!
383sbc afr 225cc fully ported heads
t72 turbonetics turbo
treadstone front mt intercooler
performer rpm intake
custom stainles steel headers and y pipe
14 psi boost
383sbc afr 225cc fully ported heads
t72 turbonetics turbo
treadstone front mt intercooler
performer rpm intake
custom stainles steel headers and y pipe
14 psi boost
11-19-2008, 08:30 AM
#6
ok so the main wells to the jts aredrilled to.180 and main body does have removable air bleeds but i havent changed them. its a ProForm main body 830cfm. thats all we did to the carb besides play w jets 80s in the front and 93s in the back. its running rich down low before the boost kicks in. it seems good at full boost i dont know for sure until i put on the wideband. thanks for your help!
383sbc afr 225cc fully ported heads
t72 turbonetics turbo
treadstone front mt intercooler
performer rpm intake
custom stainles steel headers and y pipe
14 psi boost
383sbc afr 225cc fully ported heads
t72 turbonetics turbo
treadstone front mt intercooler
performer rpm intake
custom stainles steel headers and y pipe
14 psi boost
A lot of people will block off the HSABs to begin with, and if it gets to rich up top will open them up a little bit. The Jets and PCVRs control the main fueling, but the HSABs control the flatness of the curve i.e. more air in the HSABs, the leaner it will go up top, and richer down low.
11-19-2008, 06:16 PM
#7
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Hey thanks for your help! I didn't understand the tip in thing. whats that mean? im gonna start w the air bleeds anf see how that works. I wish i knew what csu does to them. maybe i should just buy a blow through carb. thanks again man.
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11-19-2008, 09:12 PM
#9
11-19-2008, 10:36 PM
#10
http://www.theturboforums.com/smf/in...?topic=51153.0
Tip in is when the engine is at idle and you "tip" into the throttle.
11-22-2008, 07:39 AM
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ok i was way off i put a wideband on and its very lean at low rpm! Gonna try changin the pv's first see what that does. Afr ratio went up to almost 20:1 at wot at 2000rpm
11-22-2008, 09:00 AM
#12
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Damn BoostedTBSS thats a hell of a starquest!
I appreciate this thread cause im in limbo on a carb setup with a power adder.
Looks like a turbo is a pain in the ***...
I appreciate this thread cause im in limbo on a carb setup with a power adder.
Looks like a turbo is a pain in the ***...
11-22-2008, 06:38 PM
#13
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you have it reversed...turbo/efi rules! turbo/carb pita!
it's really an out dated concept and all wasted time.
how hard is it to just convert to efi...problems solved.
whats next, a nitrous steam engine?
my .02
it's really an out dated concept and all wasted time.
how hard is it to just convert to efi...problems solved.
whats next, a nitrous steam engine?
my .02
11-23-2008, 08:26 AM
#14
You can get an entire blow-through fuel and ignition system that will support 1000+ hp, tuned by the experts like CSU, for <$2,000. That includes the pump, regulator, carb, hat, and distributor. You can save $400 if you modify/tune the carb yourself.
To get a similarly capable and complete EFI system, you're looking at $4,500+ and then you have to tune it yourself! If you don't already have a laptop, there's another $1,000. Plus, tuning an EFI system from scratch isn't exactly a walk in the part.
The blow-through carbs have their place.
Mike
11-23-2008, 11:27 PM
#16
Well i really like the price of my set up!!! Freee is for mei got it passed down from some like you !!!! but the real way for turbos are draw thru!!!!!! but the tracks dont like that and dont allow it. I like that i dont need a I/C yet with my blow thru as i have no more room for one. so when my 15K build runs 8's blow thru looks real good...
11-24-2008, 11:22 AM
#17
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yea fi is great but expensive. I coulve converted but a used system would cost me about 2k and well i know a carb can work tuning i everything just like w efi except youll need a dyno to tune it. more money. I ran it at the track this weekend 11.66@ 124 not bad and i still havnt touched the carb. Whos got a blow thru for sale? How much?
