How To Turbo A Carbureted Engine Easily! |Blow Through Holley Carb Tuning | Carbureted Turbo LS

today we're going to be going over everything you need to put together a blow through carbureted setup be it a 302 a slant Stakes or even a carbureted LS it doesn't actually matter as long as you're running a 4150 style carburetor everything that I'm going to show you guys today is going to work just fine so the first thing that everybody asks me is what are you doing for fuel so on my current setup I've got a fuel cell AKA a fuel tank in the back of my truck it used to be here it is no longer here it is now hiding in the toolbox of my truck and this is an EFI style tank do you have to use this kind of tank no they sell a lot of fuel pumps that you can mount on the rail you can retrofit your stock tank this was the cheapest and easiest thing that I could do because I already had this tank now why would you need to install a fuel pump like this well there's a couple of reasons number one EFI style fuel pumps can put out a ton of fuel there are some mechanical fuel pumps that can put out a really large amount of fuel but the second thing that you need is pressure EFI style fuel pumps can put out 40 and 60 PSI no problem why that makes a big difference is because when you're deciding what kind of boost you want to run and chances are the answer is all of it once you decide what you want to run you have to make sure that the amount of fuel pressure that you have matches the boost pressure that you're applying to the carburetor what I mean by that is that if your base fuel pressure is 6 PSI and you're running 20 pounds of boost you have to actually add six PSI fuel pressure plus 20 pounds of boost and that's the fuel pressure that you need at the carburetor the reason you need to do that is because when the carburetor is under boost pressure you have to remember that it pressurizes everything so loose pressure comes in through here goes into the vent tubes on the carburetor pushes inside the float bowl and then once it's in the float Bowl it'll push up against the fuel level but it's also going to push up against the needle and seat and it's actually going to prevent fuel from coming in so let's say your fuel system could only produce a maximum of 6 PSI once you reach 5 PSI of boost you're only getting one PSI fuel pressure once you get six pounds of boost you're getting zero pounds of pressure and once you go to seven pounds of boost you're actually getting negative pressure and that's going to be one pound of fuel pressure going back into the lines and forced in there so you have to maintain a consistent fuel pressure so that's why you need to run high pressure fuel pumps in order to combat the loose pressure that's coming in in order to accomplish that you're going to need a fuel pressure regulator this particular one is made by Aeromotive Link in the description down below but it is a boost referenced fuel pressure regulator you see this line up here typically on a naturally aspirated engine you have a line that's similar to this one and what it does is when the engine sees low vacuum it will actually add fuel pressure in order to help the engine from starving at the top end of the RPM range for a boost reference application it'll add one PSI a fuel pressure per pound of boost so you actually have to run all the way down to zero and then start creating boost pressure and then that's when this thing starts coming on if the fuel pump that you're running can only support 10 pounds of fuel pressure then this thing is going to max out at 10 pounds there's nothing it can do you can't add more pressure whatever the maximum amount the pump can produce that's as much as it can produce there are other pumps that are low pressure high volume like the summit Blue Pump and red pump those are usually regulated down to like seven eight nine PSI and those will also not work you need a pump that can print out whatever PSI boost so if your goal is to run eight to ten pounds of boost figure eight pounds of boost plus six pounds you'll need a fuel pump that produces at least 16 pounds of fuel pressure as for the supply side of the fuel system I've got dash eight Supply and I've got a dash 10 return the reason the supply is smaller than the return is that if you have a buildup of pressure on the return side that pressure is going to be added to your fuel pressure so it doesn't matter if you've already backed off the regulator to what you need to if there's any pressure building up on the return side that's where you get a pressure surge or a pressure spike and that actually gets created when you have a buildup of pressure on the return side of the fuel system the supply side to the carburetor I'm actually running Dash 8 line so it goes into a t and it runs 1-8 this way and then another Dash 8 that way ideally you're going to want to run these directly off the regulator you don't want to run it off of a t this kind of acts like a bottleneck and the only reason I did it like this is because I still wanted to run this gauge right here I could have ran it up there but I wanted it right here and I didn't have the right fitting I could go out and buy the right fitting and then redo these two lines but it has been working out and I can get well above 15 pounds of boost even having it like this so for right now I'm not worried about it if you are running a fuel rail you'll find that you're actually going to run into problems so I used to have a fuel rail that came off to the back here and then this tied in here you had this T and then I had a single Dash 8 line coming into the regulator what ended up happening is that because the line came in from here and then went straight back straight and then up into the secondaries the secondaries actually had priority it wasn't until the secondaries were full that the primary would start filling up so what would end up happening is at half throttle when I'm mainly relying on the primaries the primaries would get sucked out of all the fuel that's in the bowls and I would only be running on the secondaries engine will lead now and it pops if I wasn't running E85 or if I had a lot of timing that would have hurt the motor I would have done some damage to the Pistons or rods or whatever it was so for that reason you want to stay away from fuel rails at the carburetor you're going to want to run these lines directly to your fuel pressure regulator ideally you're going to want the regulator close to the motor but I didn't really have a good place to put it so I ended up putting it here like I said you don't need to do this it's better if you have it up there but in my particular situation it works fine the next question I get is actually about the carb hat you see that it's a really flat hat this is a low profile hat this one I believe is made by Specter you can get some nicer hats from like Extreme Velocity I think that's one CSU and ProCharger also have really nice hats this isn't the best hat but it actually does the job just fine I actually made this Riser that goes under the hat and that allow allows the air to straighten out before it enters the carburetor and that really helps out the hat if you weren't running a riser you would have to run vent tube extensions up into the hat so that way boost pressure can hit the extensions and allow boost pressure to go into the bowls if you just have the hat like this without the extensions air might not find its way into the vent tubes and thus you're not pressurizing the bowls and you're going to have a lean condition I have extensions on the carburetor but only at the top and they go about two inches and then they stop because I figured that with the Riser that I have air has enough chance to turn and once it starts facing down you don't have an issue with not being able to pressurize the bowls like I said I've been over 15 psi a maximum of 24 PSI and I haven't had an issue but it doesn't mean that you won't have an issue I just currently don't have an issue the next thing I want to address is actually the intake manifold design people have asked me if I'm still running the Dual plane intake the answer is yes but I'm running an open spacer this one's a two inch spacer above that some people ask why don't I just run it directly on the Dual plane so I get that torque down low and then the boost pressure up on top and the answer to that is because of fuel distribution you want to make sure that both sides of the engine get as close to the same mix as possible because of the nature of the Dual plane one plenum tends to be smaller than the other plenum because of that one will have a different signal to the carburetor and so one side will run slightly differently to the other side if you add that plenum extension or that open spacer above the manifold get rid of not necessarily get rid of the Dual plane design but convert it more into an open plenum it allows the carburetor to offer better mixture into the cylinders but it wouldn't matter to me which intake it was I would still run an open space or above the intake manifold for that extra security for a carbureted LS you can actually go into your ignition system whether that be the Daytona sensor smart spark or the MSD system you can go into your laptop and then set up a 2d timing table if you want to run it off of a map sensor you can but you don't necessarily have to and what you can do is you can run a 2d timing table based on RPM and you can add a bunch of timing down low for drivability and then once you know you're going to be at Boost like let's say 2500 or 3000 RPMs you can ramp that back down in order to keep the engine safe at high RPM if you're running a distributor ignition system what you can do is you can run a locked distributor be it at 10 degrees 12 degrees 14 degrees whatever you deem safe or whatever makes the most amount of power under boost that's all going to depend on when you go to the dyno or you go to the tracking find out what's best for your combination as long as the fuel that you're running can support the cylinder pressure you should have no problems running it that way for those of you on a distributor ignition system that are running the older MSD 6al boxes you guys can get a piggyback unit called the tcs1 that will go in between the distributor and the MSD box and how that works is that you're going to run a locked distributor probably at like 35 36 degrees once the engine starts up the MSD the box is going to send that signal to the tcs1 and then the TCS one is actually going to turn down the timing and you'll be able to control it to whatever you want so as soon as you have power to the box and you can crank it once the MSD sees that signal it's going to be able to turn that down and you're going to have complete control so you can go ahead and add that timing down low with the TCS one you could also have a map sensor input so that we can ramp it based on manifold pressure but in order to keep things simple I always just run a 2d timing table and I haven't had any issues for those of you that want electronic control but don't necessarily have an older cell MSD box you could also pick up the cd1 ignition system that's also by Daytona sensors and that's basically just like a MSC 6al but it's on steroids it gives you way more functions I don't know the exact parameters I only know of the Box I've never actually used the Box myself but I'll leave information on that particular thing down below on a typical distributor ignition system you would have your distributor and as you increase in RPM you have the centrifugal weights inside of the distributor that actually open up and increase the timing and you'll have a base timing of let's say 10 degrees and then you'll have a total timing of about 30 degrees or 36 degrees whatever and then you'll have vacuum advance on top of that what I would do in that scenario is you would have to lock your distributor down and so you don't have any kind of mechanical advance but I would leave the vacuum advance that way when you're cruising around the street you're still getting that extra 15 degrees or whatever part throttle so that we get a little bit more drivability but then when you floor it that vacuum advance is going to go away and you're going to run off of initial timing where something can go wrong is that if you have any kind of binding or your diaphragm is not working or something else and your vacuum advance gets hung up and let's say with the advance you're running 25 degrees and then it gets stuck on 20 and now you're running 20 degrees on a pretty high amount of boost you're asking for trouble so in order to prevent that I would just run a locked distributor and the last item on our list is that you're going to need a double pumper style carburetor and the reason for that is because one you have to have that rear medium block for tuning two you can't have any kind of vacuum secondary because under boost you won't actually be able to have that open up and the third reason is because you can't have anything rely on engine vacuum because it's not going to work under boost so carburetors that operate off of different kinds of vacuum signals will not work properly in a blow through setup which is is why running just a mechanical secondary standard 4150 style carburetor is the way to go the carburetor itself is also a special piece you can't just run any kind of off-the-shelf carburetor you have to have a carburetor that's designed to work with Boost this particular carburetor that I have is an older Barry Grant alcohol 650 demon that I've converted to gasoline then I convert it to E85 and then I convert it to blow through if you want to build a carburetor for your own blow through setup you're going to need to learn how to do every single circuit on a 4150 style carburetor if you guys are interested in what I did to make my carburetor work go ahead and leave me a comment below I will see you guys all in the next one night wrencher out

Channel: NightWrencher

Views: 77,507

Keywords: turbo ls, carbureted ls, holley carb tuning, holley carb adjustment, carbureted turbo, blow though carb, blow though, blow thru, blow thru carb, diy blow through carb, how to build a blow through carb, diy blow thru carb, holley carb, holley carb tuning secrets, holley carburetor, turbocharged, turbocharged ls, holley carb secrets, diy turbo build, turbo build, ls swap, budget build, junkyard turbo ls, draw through turbo, draw through turbocharger, blow thru turbo

Id: HYElRJoWIHI

Length: 12min 34sec (754 seconds)

Published: Fri Dec 23 2022