So ive been playing with the idea of boosting my s10, its a 97 4.3 pulled from a junkyard, did the gaskets all the way around on it. I got a good deal on a meth injection kit and a turbo and i would like to do it with a carb. I already have edelbrocks intake for a carb on it with a new low pressure fuel pump and hei distributor with vacuum(i belive) time advance. I want to pick up a holley hp carb to handle the major business but ot seems tuning a carb for turbo is a nightmare. Is it as annoying as it seems or am i looking to much into it? With the turbo im only looking for about 7 pounds to daily on(daily drive truck) what ive gather so far is with the holley hp carb i dont need to worry aboit modify a carb and with the features of the carb i wont have to worry about fuel being leaned out in the carb, but i still need to make sure the timing is right for the turbo. I should be able to use the vacuum advance option on my distributor to set the cruise and idle timing advanced. Also need to get a oil cooler as well. With the meth kit i was planning on putting it directly into the intake after the carb as a fuel additive. Should i put it before the turbo to help the cool down? Also am i missing anything? Im mostly worried about getting the carb and tune right so to not blow a motor.

 

Also what would be a good way to add in fuel pressure with boost? Id like to keep as much of this mechanical as possible

 

Contact c&s specialties (vendor link will be to the right of the thread), they specialize in blow through carbs and you will have the person who builds the carb to talk to if something isn't working the way you want. Chances are good it will work well out of the box.

Any 1:1 fuel pressure regulator can do what your asking, C&S can help you with that too.

Put the water meth as far upstream as you can, but after the intercooler if you are running one. You want it to have as much time in the intake tract as you can get to max the evaporation time.

 

I just got my 88 4.3 s10 up and going...runs pretty darn good for what I did. No high dollar stuff either. Syclone repop manifolds an h1c holset turbo and edelbrock 500 cfm carb. Hei distributor limited to 20 degrees timing plus vac advance for cruising. Right now I'm running 6-7lbs and still working a few bugs out, but we're getting there. Any questions feel free to ask. Maybe I could steer you in the right direction. Good luck!
Joel

 

I’m in the same boat as you except I’m using a V8 and centrifugal supercharger. Same research though. I have never done any of this blow through stuff and have no practical experience. However, I have done a tone of research. Seems you have to get a few things right before even worrying about the carb. 1. You need to have a fuel pump that is rated at your max HP levels along with your fuel line size. 2. From what I read, fuel pressure is super important and you will need to run a boost referenced fuel pressure regulator. Where it bumps up the fuel pressure one psi per every one pound of boost. It should be referenced off the hat. Some guys even turn the tube in the hat towards the incoming air for a better signal. Some cut a bevel facing towards the incoming air. Some guys run two fuel lines from the regulator to the bowls to prevent fuel starvation. These are all high boost applications though. I’m only going to run 5-8 psi so we may not need to get to crazy with it.

As far as your question about increasing fuel under boost, I’m still a bit confused and started an entire thread on it. It’s based on the power valves. Specifically the boost referenced power valves. Seems they do a great job opening up and enriching the circuit under boost, but us low boost guys, especially the centrifugal supercharger guys, where boost comes in late in the upper RPM’s, I can’t wrap my head around how the carburetor will provide more fuel under a light load at cruise before boost without the standard vacuum referenced power valve. I was thinking of running a standard one on the primaries and a BRPV on the secondaries.

Still researching.

Other than that, some of the basics that can be done to the carburetor like nitrophyl floats and stuff like that. Honestly, I would buy one dedicated to blow through that was build by a professional.

Thats all I got. There are way way way more knowledgable people here that may chime up.

 

Check these out, might help...he was a member on here one time....

 

wow! Thanks! Great info! I can’t believe I did not find those video prior to my post.

I guess my problem is I don’t know how to dial them in.

I’m debating just going with a Holley Sniper XFLOW unit with 4 X 120 lbs injectors. I think I may be able to be better at tuning via fuel maps and so on. There is a ton of info online plus people are willing to help all over the country via remote log in. The carburator tuners are few and far between and do not give up their secrets or help anyone learn how to tune.

i just like the reliability and cool factor of a carb.

im still lost on the power valves. I don’t understand how standard power valves still work with boost without being forced shut. I’m even more confused on the BRPV and how the engine would get enrichment under load before boost kicks in and not run lean.



so far, I have found a lot of help online for the Sniper, but the few carb guys just want to sell me a carb then charge me to set them up. Which I’m ok with, but there are none close to me.

 

Under light load to moderate load with a BRPV, a combination of low speed bleed(aka idle air bleed), hsb, and booster type, will keep it happy before boost. This is where known good blowthru carb builders have that combination all worked out.

 

thanks for the info! That’s my issue. I can’t find a good carburetor tuner within central Florida let alone blow through one. Thats why I’m consider if EFI, I can find a tuner anywhere. I prefer a carb though.

 

what is HSB? High speed booster?

 

hi speed air bleed

 

CSU for gasoline. Mod or build new for you.

 

I hear great things about CSU, but where would I go to dial it all in once installed. I would just screw it up.

I met a local guy in the area yesterday at a small car show in front of a parts house who told me he could build and tune a blow through for me. He said at 5 psi of boost, BRPV’s are not needed. He would just use a higher number PV. Does that sound legit?

It’s the closest I got to finding someone local.

 

ok, I see what you mean. Idle, transition, and main jets for everything less than boost. BRPV for boost.

 

Sure, if he's known to be good at it , or has some examples he can show you.

The powervalve, its kinda application specific even NA. Higher number will open at a higher vacuum.