tfreer85 Posted November 13, 2004 Share Posted November 13, 2004 Okay, I'm sure that this has been answered before, but I've been searching for 3 hours now and can't find anything. I own a 72 240Z, what I'm wanting to know is if i can run a turbo or twin turbo system through this engine, with out having to run an ECU. I figured upgrade to a 4 barrel carb to help out with fuel, upgraded fuel pump, and upgraded to an MDS ignition system. What other type of modifications would i have to make this work? Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 13, 2004 Share Posted November 13, 2004 I think the search feature is not working right... this forum is being worked on right now so it may not be working... if it is, there is DEFINATELY info on this question in there somewhere. Well... I'll try to give you a brief answer (I'm not well known for keeping it brief ) A few guys have run turbo's on the stock SU carbs. You'll have to custom make an intake manifold, and you can only do this as a 'suck thru' setup, meaning, the carbs have to be first in the intake setup, and then the turbo compresses and feeds air and fuel directly into the cylinders. Not the most ideal setup... most everyone who's tried it has cited tuning issues and lean running problems. SU's were never intended to flow much more air or fuel than the stock 2.4L motor needs. You could run a turbo on a 4bbl carb.... I think you can do this as either suck thru or blow thru but I'm not 100% on that... you have to mind some details like building an air tight box around the carb though. And of course, you're going to be custom fabbing lots of piping. There's definately info on this to be found here, either in the turbo/supercharger section, or in the V8 sections. There are a couple guys who run turbo'ed, carbed V8's in their Z's here. Applying that info to an L6 shouldn't be much different. However... you should also look into all the debates on the efficiency of running a 4bbl carb on an inline 6 motor. The common consensus is it's not the best idea in a peformance application, as there are issues with equal fueling of all six cylinders, due to the fact that the runners on the 4bbl manifold are of such unequal lengths (Note: is there no type of balance tube apparatus on the 4bbl L6 manifold, as there is on the stock SU manifolds? Could something like a balance tube solve this problem?). DEFINATELY not the kind of thing I'd want to mess with if I was doing a turbo setup, but it can be done. If you absolutely had to go with a 4bbl and forced induction, I think it'd be easier to go with a supercharger over a turbo... since there are already so many SC's out there that are designed to bolt right on to 4bbl carbs, as opposed to doing a turbo where you have to custom fab all the piping and the airtight box. Then again... you'll still most likely have to custom fab either an intake manifold to sit lower, or a hood with a pretty big bulge in it! Figure the manifold, SC, carb and air filter are going to add some height to the engine Quote Link to comment Share on other sites More sharing options...
datsunlover Posted November 13, 2004 Share Posted November 13, 2004 Well, as for the SU's I would think some bigger ones (like from a Jag perhaps?) would solve any fuel 'starving' issues.. But a custom intake is definatly going to be needed.. I think the old buick GN's used a 'suck through' system as well (someone correct me if i'm wrong) where the turbo boost gets routed through a 'port' on the intake, under the 4bbl carb, sucking fuel through.. (I could be off on that though..) maybe the stock Z intake could be modified to accept something like this.. but I'm sure I read somewhere about being able to 'presurize' the SU's and run a 'blow through' system... Quote Link to comment Share on other sites More sharing options...
Clifton Posted November 13, 2004 Share Posted November 13, 2004 The first turbo car I had a ride in was a 240Z in 90' with a blow through 4 barrel. It was fast enough to make me forget about the tripple carbs/cam/pistons I was saving for. I was turbo'd a few months later. He used a Holley blue pump and regulator running boost to the vent port on it. Run a Holley not a Carter, the accel pump is not covered by the plenum/bonet and will spray a little gas under boost . You could still run the stock turbo exhaust manifold and turbo but would have to get a real 4 barrel intake manifold, not one of the bolt on to the SU adapter ones, they won't clear the turbo. Quote Link to comment Share on other sites More sharing options...
510six Posted November 13, 2004 Share Posted November 13, 2004 You might check some of the VW forums as the draw thur 4 barrel turbo setup is very popular.A MSD boost timimg master would help to retard timing under boost.A stock turbo manifold and a turbo that would work with a draw thru setup. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted November 13, 2004 Share Posted November 13, 2004 He used a Holley blue pump and regulator running boost to the vent port on it... Um.. huh? Sorry if this sounds retarded.. but.. vent port on what? The fuel regulator? Could you explain this a little more? I'm confused.. Quote Link to comment Share on other sites More sharing options...
510six Posted November 13, 2004 Share Posted November 13, 2004 The regulator has a port to increase fuel pressure on a 1-1 ratio with boost.I used the same style regulator for the fuel side of my nitrous system it would increase the fuel pressure as boost came up to compensate for the greater pressure in the manifold.If I was running 6psi fuel pressue + 14psi of boost the boost port on the regulator would add 14psi of pressue.I used a Holley blue pump as well with the output pressure increased to 25psi. Quote Link to comment Share on other sites More sharing options...
mjfawke Posted November 13, 2004 Share Posted November 13, 2004 A friend of mine ran a 2 inch SU with twin float chambers in front of a TO3, methanol "injection" in front of the carb, and approx 7.5:1 compression on the L28. It broke numerous gearboxes, ripped the front diff mount off once (taking out the handbrake assembly as well), and wore through a few R180's over the years. He hated it - wouldn't run properly in hot weather, would occasionally flood the motor, and was a general pig to keep tuned. He switched to injection as soon as programmable EFI became available. Quote Link to comment Share on other sites More sharing options...
tfreer85 Posted November 13, 2004 Author Share Posted November 13, 2004 You guys are talking about using a turbo manifold and intake from what exactly? Also if you running a four barrel carb with a blow through style turbo, the only thing the carb needs to do is provide fuel right? So why not use run rich through the carb to help prevent detonation. Someone was saying that the 4bbl carbs don't provide fuel evenly, but should that matter considering the air is being forced through it? One more question with the 4bbl intake manifold can you use any 4bbl card at all? Quote Link to comment Share on other sites More sharing options...
Clifton Posted November 13, 2004 Share Posted November 13, 2004 A turbo manifold from a 280ZX turbo. If you run richer than you need to you will loose power. Yes you can run 10:1 in order to run a few psi more but you will make more power running it leaner with less boost. To say they don't provide fuel evenly is arguable without hard data to back it up. You guys are talking about using a turbo manifold and intake from what exactly? Also if you running a four barrel carb with a blow through style turbo, the only thing the carb needs to do is provide fuel right? So why not use run rich through the carb to help prevent detonation. Someone was saying that the 4bbl carbs don't provide fuel evenly, but should that matter considering the air is being forced through it? One more question with the 4bbl intake manifold can you use any 4bbl card at all? Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted November 13, 2004 Share Posted November 13, 2004 Most Turbo/Supercharged motors are low compression around 8 to 1. The compression ratio is upped by the boost pressure. From the information that I have found for every 1 psi of boost you are looking at about a 7% hp gain. I have a 260Z with a 280 motor. I am it the middle of the design phase of installing a supercharger with carburetion. I do not have to deal with lubrication on a supercharger. Suck through is the simpler of the options. You can still have all of your vacuum operated systems work, heater controls, vacuum advance, brake booster, and do not have to deal with fuel pressure changes due to boost. Eaton does not recommend using their superchargers wet. The rear bearing are grease packed without seals. I have found a couple of TR6s with Eaton superchargers using a large single SU carb. I have went back and forth on which way to go and have everything fit in the space available. With the Eaton M62 supercharger that I have the best place to fit it is where the air conditioner compressor used to be. This puts the carburetor next to the exhaust header, not a good placement. I bought an Edelbrock performer 4 barrel it will not fit in this space between the strut tower and the manifold. Bought it on ebay sell it on ebay. So watch the 4 barrel dimensions. Also there are a lot of places for fuel to accumulate in the piping especially with inter cooling. I was planning on using an intake manifold off of a 280z and plug the injectors and all of the other non needed openings. Last weekend I scored a set of triple 45 mm SK Racing carbs and manifold and am now looking at forced induction. These carbs like Webers and have the float bowl vent on the face of the carb on next to throat and do not have to be boxed in. According to my Weber book will work with forced induction. I’m looking at using a piece of 4†square tube stock for the intake header manifold. There is the problem of vacuum to be addressed. A MSD adjustable ignition box will have to be used on for the distributor advance. I have found a fuel pressure regulator that will adjust with manifold pressure. But there are still a lot to be worked out. Here is a picture of a 240z with a wet supercharger Quote Link to comment Share on other sites More sharing options...
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