Cjarloz Posted December 26, 2003 Share Posted December 26, 2003 Ok this is my first post here but here goes. I am in the process of converting my 71 240z into a turbo L28 83' z with dished pistons. Heres the curve ball im not going fuel injected . I am using a holley 4 barrel 600 doublepump and im pressurizing the 4 barrel via a turbonetics intake plenum connected to a frod probe intercooler and a stock T3 turbo. I also have an R200 3.54 rear end. Can anyone help me understand what kind of hp gains i will have compared to a fuel injected turbo at 7 or 8 psi. Aswell what kind of power gains Any help or input will be greatly appreciated thx. Carlos Quote Link to comment Share on other sites More sharing options...
Tim240z Posted December 26, 2003 Share Posted December 26, 2003 The Holley 600 will be wayyy to big for the inline 6 application. Tim Quote Link to comment Share on other sites More sharing options...
Cjarloz Posted December 26, 2003 Author Share Posted December 26, 2003 I dont think its two big if its run with just two barrels operating at 300 cfm Quote Link to comment Share on other sites More sharing options...
Guest 4.3L 280z Posted December 26, 2003 Share Posted December 26, 2003 Does the intake plenum go around the carb? I was thinking about doing the same thing with a centrifugal super charger. Let me know how it goes. Quote Link to comment Share on other sites More sharing options...
Cjarloz Posted December 26, 2003 Author Share Posted December 26, 2003 yes it goes on top and pressurizes the carbs Quote Link to comment Share on other sites More sharing options...
Guest 4.3L 280z Posted December 26, 2003 Share Posted December 26, 2003 do you know a link for it? Is it just a hat that goes on top or does it pressurize the whole carb? Quote Link to comment Share on other sites More sharing options...
Guest 4.3L 280z Posted December 26, 2003 Share Posted December 26, 2003 also wouldn't a 600cfm carb be ok? Some people told me that my settup w/ a sc with a 390cfm would be way to small. Quote Link to comment Share on other sites More sharing options...
Cjarloz Posted December 26, 2003 Author Share Posted December 26, 2003 well my carb is 600 cfm i belive. not sure dads the expert. im mostly jsut the driver. so i think it should work um crap i dont got a link ill try and find one for ya. Quote Link to comment Share on other sites More sharing options...
DavyZ Posted December 26, 2003 Share Posted December 26, 2003 also wouldn't a 600cfm carb be ok? Some people told me that my settup w/ a sc with a 390cfm would be way to small. Lets see, a 600 cfm carb on a 350 hp 5.7L Chevy is about right. That feeds a motor that is twice as big as yours. Funny, Chevy guys always talk about over-carbing their motors, and bigger is not always better, even with forced induction. Perhaps some of the experts can chime in. Just looking at what you have, a 390 cfm Holley would be more then enough from what I have read. Davy Quote Link to comment Share on other sites More sharing options...
Tony D Posted December 28, 2003 Share Posted December 28, 2003 well, at 15psi, the 2.8L is roughly 5.6 litres at 6500 rpm, so the 600cfm might be just about right. That, and the fact that my old draw-through system would run 12.27 to 12.40 at about 17psi and it used a vacuum actuated holley 650.... When dealing with N/A applications, a Z will also effeectively use a 650 as we had one for a few passes at ElMirage, until we went to Webers which have a flow potential of 1100cfm, which is "way too much" anynway. Theory goes out the window when racing is involved. Results are results. Don't get hung on theory. Quote Link to comment Share on other sites More sharing options...
Pyro Posted December 29, 2003 Share Posted December 29, 2003 I have seen a 750 holley run great on a 58 VW bug with a 1600 cc engine with a draw through at 14 psi (11.9's at 120). So i'm sure a 650 will work with a 2.8. To figure hp gains from a turbo do the following equation. (14.7 + boost)/14.7 = "hp multiplier" Then use the "hp multiplier" on the hp of the engine WITHOUT a turbo and the new hp is estimated. For example: a L28 with 10 psi of boost. (14.7 + 10)/14.7 = 1.68 Stock hp at the wheels is 135 hp. 135 hp x 1.68 = 227 hp (at 10 psi of boost) Quote Link to comment Share on other sites More sharing options...
Cjarloz Posted December 30, 2003 Author Share Posted December 30, 2003 thx guys for the input but i neglected to mention that this will not be a draw through system. muahahahaha the turbo will presurize the 4 barrel on top. via a plenum at roughly 8 psi to begin with, until we get it tuned and funtioning at peak. Quote Link to comment Share on other sites More sharing options...
dmyntti Posted December 30, 2003 Share Posted December 30, 2003 With a draw through setup you would need a bigger carb to flow the amount of air required to feed the HP level you are after. With a blow through the air going into the carb is compressed so you don't need to increase the carb size. Quote Link to comment Share on other sites More sharing options...
BillZ260 Posted December 30, 2003 Share Posted December 30, 2003 So you are going to be pushing the fuel air mixture through the intercooler? I thought that was explosivly dangerous? Quote Link to comment Share on other sites More sharing options...
orklc Posted December 30, 2003 Share Posted December 30, 2003 The T3 is going to feed the IC and the intercooler is going to feed the Holley from the top via a turbonetics air plenum. Additionally, we are going to have a Mallory boost sensitive fuel regulator with a return line to the gas tank as well as a Mallory electric fuel pump capable of handling even FI if we wanted to go that way. We are also planning to keep the boost under control with a manual boost adjustment controller and the HKS blow off valve. There will be a gauge to keep track of the exhaust gas temperature. Additionally, we are installing the L28et oil cooler and 2.5" to 3" downpipe and exhaust system. Next will be a stand alone electronic ignition with capability to retard timing based on boost. A NOS plate under the holley for an additional 50 - 75 extra HP (No turbo Lag hopefully). It is just not happening all at once. Will keep things tamed around 7-10 ponds of boost until we go through the learning curve. The mecahnical 600 holley may give us the control we need to keep things in line on low boost condition. My guess is that a two barrel holley at 300-500 cfm should be quite similar to the mechanical 4 barrel (double pumper) under higher boost conditions. Quote Link to comment Share on other sites More sharing options...
BillZ260 Posted December 30, 2003 Share Posted December 30, 2003 So does the carb need to have special seals to be pressurized or can they handle that type of enviroment? Quote Link to comment Share on other sites More sharing options...
Pyro Posted December 30, 2003 Share Posted December 30, 2003 No, because the whole carb is pressurized. However, the fuel pressure needs to be increased as the boost is increased. The fuel pressure should be 5 to 7 psi greater than the pressure the carb "feels". So at 0 boost, the pressure should be 5 to 7 psi and at 8 psi of boost the fuel pressure should be 13 to 15 psi. The outer edge of the fuel lines need to be sealed to pressure box. Quote Link to comment Share on other sites More sharing options...
BillZ260 Posted December 30, 2003 Share Posted December 30, 2003 Sounds like a cool induction system, I want to see PICS! Quote Link to comment Share on other sites More sharing options...
orklc Posted December 30, 2003 Share Posted December 30, 2003 There are a number of mods needed due to the fact that we are not enclosing the entire carb. The Holley manual has a chapter on the mods needed to pressurize the carb from the top. The yahoo blow-through-carb user group also has plenty of information on the mods needed. Basically you need to eliminate the power valve (it is a back fire problem any way on older carbs) and re-jet 2 - 3 size up to compensate the power valve loss. You also need to change fuel floats to non-collapsible type, and seal vents of the fuel bowls. You also need a boost reference line to seal the throttle shafts and that is done from the bottom of the carb via a small spacer drilled in the proper place to align with the shafts. The carb full enclosure is a big project ($ + many technical requirements) due to the number of items that need to be able to interact with the carb (fuel lines, linkage, other hoses) additionally the space requirements are a problem on the L6 and under the hood space. We are still going to have some clearance problems so we are probably going to open the hood area above the Turbonetics intake plenum and add some kind of a scoop or bubble (like Mitsubishi Eclipse hoods) just to make sure we have no issues there. The installation should look pretty clean. By the way the intake manifold is the old Bob Sharp racing 4-barrel manifold. Similar to the one that Arizona Z car sells I believe. Quote Link to comment Share on other sites More sharing options...
Guest 4.3L 280z Posted December 30, 2003 Share Posted December 30, 2003 I made a bubble on mine. Quote Link to comment Share on other sites More sharing options...
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