dr_hunt Posted January 31, 2006 Share Posted January 31, 2006 This may not be the right place, but it's here and I thought it might provide some info in case others plan on doing a blow through application someday. I was going through the Banks Holley 750cfm double pumper and freshening it up in preparation for use. The primaries had 72 jets and a 6.5 power valve which should be close considering the duration on my cam. The gaskets were all shrunk up so I replaced powervalve and all gaskets with the QFT non-stick blue ones. The secondaries had no power valve and 100 jets. Maybe Hanns can help me here what jets do you run and does that seem OK? The carb is extensively modified internally and has all kinds of holes and grooves milled on the bottom of the base plate. The motor is coming along nicely, balance job is done, got the block touch honed to get crosshatch back, got the custom roller cam, lifters, springs, heads done with new guides, valve job, flat milled .003, cometic head gaskets, and it's all ready to go later this week. I bought moroso block fill and I'm going to do a short fill on the block to stiffen up the cylinder walls. I talked to speed dreams in Alb. about getting the dyno and their tuner around later to throw it on the wheels and see if we can get it tuned properly and also get some idea of what kind of power it will be laying down. The converter should ship friday and I get one free restall if I need it. Rebuilds are $80. It is a billet converter with anti balloon plates, spragless, set up and stalled for 850HP and 700TQ right now. It'll have to be redone if I turn up the boost since it'll play hades with the stall. Quote Link to comment Share on other sites More sharing options...
Turbo Meister Posted February 3, 2006 Share Posted February 3, 2006 This may not be the right place' date=' but it's here and I thought it might provide some info in case others plan on doing a blow through application someday. I was going through the Banks Holley 750cfm double pumper and freshening it up in preparation for use. The primaries had 72 jets and a 6.5 power valve which should be close considering the duration on my cam. The gaskets were all shrunk up so I replaced powervalve and all gaskets with the QFT non-stick blue ones. The secondaries had no power valve and 100 jets. Maybe Hanns can help me here what jets do you run and does that seem OK? The carb is extensively modified internally and has all kinds of holes and grooves milled on the bottom of the base plate. The motor is coming along nicely, balance job is done, got the block touch honed to get crosshatch back, got the custom roller cam, lifters, springs, heads done with new guides, valve job, flat milled .003, cometic head gaskets, and it's all ready to go later this week. I bought moroso block fill and I'm going to do a short fill on the block to stiffen up the cylinder walls. I talked to speed dreams in Alb. about getting the dyno and their tuner around later to throw it on the wheels and see if we can get it tuned properly and also get some idea of what kind of power it will be laying down. The converter should ship friday and I get one free restall if I need it. Rebuilds are $80. It is a billet converter with anti balloon plates, spragless, set up and stalled for 850HP and 700TQ right now. It'll have to be redone if I turn up the boost since it'll play hades with the stall.[/quote'] David, I can tell you what works for me but I thought you are going Alcohol. My 750 DP..Choke horn cut off, 81 primary jets with 2.5 PV (to delay opening as long as possible), No PVCR modification at this time, .030 high speed air bleeds, 95 secondary jets with no power valve, 120 needle & seat. Air/Fuel ratio between 11.1 and 11.5 at WOT. Getting closer:) Hanns Quote Link to comment Share on other sites More sharing options...
John Scott Posted February 3, 2006 Share Posted February 3, 2006 dr hunt, I know T-Meister was using a referenced mechanical pump, wondering what type of regulator you were planning to use. Not trying to P!$$ with the big dogs here, but had some personal experience with my 4.3 using electric fuel pump and the Boost referenced Mallory 4 port... and how to get it to run right. Maybe the new boost ref. regulators don't have the gliches of the old Mallory and this will all be pointless. More to it than just running a line to the reference port. With the Mallory, correct fuel pressure at vacuum conditions and then having too much at boost used to befuddle me, i.e. 7 psi from vacuum to 0, AND consistant 7psi over boost to 16 psi (23psi fuel)boost. Easy to overwhelm the needle and seat on a holley. Had a crankcase of gasoline once testing the system. Stupid me. Found very simple solution to get it right in all conditions. Won't say any more if you already got this figured out. John Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted February 3, 2006 Author Share Posted February 3, 2006 No, I need to know. I've decided to go with gas for now, but the fuel system is built for alcohol and I have a blow through alcohol carb and at some point I'm going to change. Banks is so secretive about the turbo's and I was finally able to get a compressor map from turbonetics, who bought out rayjay, they are an e trim T exhaust housing turbo that is a T4 flange with a 4 bolt flanged exhaust and uses a divorced BOV, unlike the T3's. All the turbo calculations, advice, experts, bench mechanics say that the turbo's won't sustain over 900HP except at 22 psi boost and the map shows that to be on the left side of the curve close to the surge limit, so I'm thinking about that real hard. Banks says they will, we'll see. Anyway, until I get all the bugs worked out, I'm going to leave the system as it was designed, mainly because I don't really know what the heck I'm doing with turbo boost and blow through carburation. So, leave it as it's engineered, I ordered the Corky bell maximum boost book, I'll learn what all you guys know, and go from there. If it turns out that I need turbo's, I'm being told that a pair of GT42's would fit nicely on there and I could boost 30psi easily on alcohol! Fuel pumps, I have several, for gas I'm going with the A1000 and the Aeromotive carb application boost referenced fpr. I have a mechanical Banks modified fuel pump also, but I like electric and for my hp level the mechanical might fall alittle short, besides with roller cams you have to have a special roller fuel pump push rod and I've had problems with those before cause back in the old days we didn't have the electric fuel pumps that are available today. Damn it sucks to be old and remember that kind of stuff. Quote Link to comment Share on other sites More sharing options...
John Scott Posted February 3, 2006 Share Posted February 3, 2006 The boost referenced Mallory 4 hole (one in, two to carb, one return) used a port at the top of the unit to control fuel pressure relative to boost. (Mallory is probably way too small for your application.) The flaw was when you set the pressure to 7 psi at 0 engine vacuum, anytime the engine would see vacuum the fuel pressure would fall to the point where the car wouldn't run, or safely so. Set pressure to work with crusing vacuum and too much pressure at low boost would overwhelm the needle and seat. Mallory was of no help, so I came up with the idea of adding a 1/8" power brake booster check valve, and put it in line with the regulator port. Now anytime the engine would draw vacuum, the valve would close and keep the regulator thinking it was at 0, rather than vacuum, thereby maintaining a constant 7psi at vacuum conditions. Testing the system, plug the lines going to the carb, (I just looped them back on themselves, the second time!) with an in-line fuel presure guage. Use another guage cabable of reading what boost you are going to run, in line with the port on the regulator. With fuel pump running set fuel pressure to 7psi, this will be the base pressure at 0 vacuum/boost. Then add pressure from hand pump or other source to regulator port and confirm your fuel pressure is rising with pressure. 7 psi on the regulator port should result in 14 at the fule lines. 15, 22 and so on. Don't laugh, but my mistake was testing this with the lines still on the carburetor and filled the cylinders and engine up with gas so fast it was running out the manifold. I ran to uplug electricals in the garage, and had quite a mess to deal with. Holley needle and seats fail around 11 psi. I was hoping that newer regulators have addressed this problem and now have check valves that don't let vacuum effect the fuel pressure. BTW I used just a carb hat, sealed choke linkage hole (JB) milled choke horn, nitro floats, same needle and seat as Turbo meister, 6.5 PV, primary jetting close to NA, plugged rear PV a few steps richer. 7.5:1 forged, cam was 232 @ .050 114 lsa, but only had 262 cu in. Start way rich. As you know, under boost by the time you found out you are too lean, its probably hurt something. Don't want those pretty new pistons to look like whiffle balls! John Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted February 4, 2006 Author Share Posted February 4, 2006 Thanks John and Hanns, I'm sure others will follow the blow through turbo route at some point with another v8 of sorts and this will definately help. I can see the fuel pressure thing being a problem. With alcohol it is critical to see the fuel pressure at the carb inlet so that is one of my gauges already, so that coupled with a good boost/vacuum gauge will definately tell me what's going on. I picked up the motor parts from Edwards today, $2700 in machine work and parts, OUCH!!! The custom billet roller with a cast iron gear looks really nice, but they didn't have that lobe offering in a 4/7 swap, so it's standard firing order for now. The vavle spring requirements were outrageous so I got new springs $350. 250# on the seat and over #600 open. Cam is 244/250 .618/.630 114LSA as delivered. A little shorter duration on the exhaust than what they had previously recommended, but they said that the Banks exhaust manifold was extremely efficient. Should be good to 8K rpm although I doubt I'll turn that much. The rotating assembly was 1900+ bobweight so it's heavy. Interesting enough the TRW pistons were perfectly balanced from the factory, absolutely no material had to be taken off any pistons! Simply amazing, they weighed 711 grams with pins and double tru arc locks on both sides. Lead slugs. I'll take some pic's as it goes together and put them in the album. Quote Link to comment Share on other sites More sharing options...
Turbo Meister Posted February 4, 2006 Share Posted February 4, 2006 The flaw was when you set the pressure to 7 psi at 0 engine vacuum, anytime the engine would see vacuum the fuel pressure would fall to the point where the car wouldn't run, or safely so.Set pressure to work with crusing vacuum and too much pressure at low boost would overwhelm the needle and seat. John, I have never had the problem you described. My fuel pressure is set at 6 psi and it remains there while I'm cruising with 12 in. vacuum. Under full 17 psi boost the fuel pressure rises, 1 to 1, to 23 psi. Off boost it immediately drops back to 6 psi. My needle and seat has never been overwhelmed. I'm using the A1000 Aeromotive fuel pump and Kenne Bell Boost-A-Pump set at 18 volts. The only problem I had was when the regulator could not return the excess fuel to the tank fast enough while idling in heavy traffic. The pressure would then rise up to 10 psi and cause rough running after some time. Now I use a 10 AN return line and should not have this problem. The fuel pump is providing 45 psi to the regulator at 12 volts so I know it's higher than that at 18 volts. Hanns Quote Link to comment Share on other sites More sharing options...
Turbo Meister Posted February 4, 2006 Share Posted February 4, 2006 All the turbo calculations, advice, experts, bench mechanics say that the turbo's won't sustain over 900HP except at 22 psi boost I believe I mentioned to you previously that I have the E-trim, 80 A/R ratio Rajays. By only changing the turbine housings to 60 A/R ratio, the engine produced 30 psi boost. However, the Z could not handle the extra power and just melted my tires. Also my old fuel pump could not provide the required 36 psi pressure and melted a piston. Maybe I'll try the 60's again now that I have a better pump. :nono: And maybe a 2-step launch control will allow a low boost start. Hanns Quote Link to comment Share on other sites More sharing options...
Turbo Meister Posted February 4, 2006 Share Posted February 4, 2006 The flaw was when you set the pressure to 7 psi at 0 engine vacuum, anytime the engine would see vacuum the fuel pressure would fall to the point where the car wouldn't run, or safely so.Set pressure to work with crusing vacuum and too much pressure at low boost would overwhelm the needle and seat. John, I have never had the problem you described. My fuel pressure is set at 6 psi and it remains there while I'm cruising with 12 in. vacuum. Under full 17 psi boost the fuel pressure rises, 1 to 1, to 23 psi. Off boost it immediately drops back to 6 psi. My needle and seat has never been overwhelmed. I'm using the A1000 Aeromotive fuel pump and Kenne Bell Boost-A-Pump set at 18 volts. The only problem I had was when the regulator could not return the excess fuel to the tank fast enough while idling in heavy traffic. The pressure would then rise up to 10 psi and cause rough running after some time. Now I use a 10 AN return line and should not have this problem. The fuel pump is providing 45 psi to the regulator at 12 volts so I know it's higher than that at 18 volts. Hanns Quote Link to comment Share on other sites More sharing options...
John Scott Posted February 4, 2006 Share Posted February 4, 2006 John' date='I have never had the problem you described. My fuel pressure is set at 6 psi and it remains there while I'm cruising with 12 in. vacuum. Under full 17 psi boost the fuel pressure rises, 1 to 1, to 23 psi. Off boost it immediately drops back to 6 psi. My needle and seat has never been overwhelmed. I'm using the A1000 Aeromotive fuel pump and Kenne Bell Boost-A-Pump set at 18 volts. The only problem I had was when the regulator could not return the excess fuel to the tank fast enough while idling in heavy traffic. The pressure would then rise up to 10 psi and cause rough running after some time. Now I use a 10 AN return line and should not have this problem. The fuel pump is providing 45 psi to the regulator at 12 volts so I know it's higher than that at 18 volts. Hanns[/quote'] Hanns, The mallory '94 vintage(?) also would have a rise of 1 to 1, but was affected by vacuum as well. Sounds like your regulator addressed this problem. What brand are you using? I though you had a mechanical pump, or was that an earlier engine? Larger return than supply lines are a must for good regulation. Mallory wanted at least same size, bigger is better. This also lets your pump run easier until needed since little resistance. My old engine was a stock 2 bolt block restricted vortec heads, the first Vortec series '85, merely dabbling in the supercharged world. I learned a lot. Twin turbos have always been a fantasy, so Its going to be great following these horsepower monsters. John Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted February 4, 2006 Author Share Posted February 4, 2006 The A/R on the turbine side on these is 1.0. I don't know about the compressor side. I'd have to take it apart to measure that, but it's kind of pointless IMO. The real test will be in the pudding. Assembling the pistons on the rods last night and I'm missing 2 tru arc's, so I'll just file the rings to fit the bores, wait for the tru arc's, install the crank and cam in the block and see if the gear drive fits. I did get the cast iron gear option on the cam for another $30 so I'm going to run stock drive gear on the dizzy. That'll be a load off my mind. Anyone need a cloyes aluminum front cover for a sbc with a BBC snout? Blower applications, kind of got rooked on EBAY last week. It'll probably take me several weeks to assemble this thing, alot of measuring and checking goes in before the label goes on. Then the turbo exhaust has to be redone where the WG's go into the downpipe. The carb hat has a BOV built in that exhausts right behind the carb but in front of the dizzy. Also it has a complete water injection system with all braided lines and a 3 gallon tank. The nozzles are right in front of the turbo inlets and look like a NOS nozzle and the tank is feed boost pressure through an orifice to push the water out during boost only. Kind of an ingenious setup that is almost foolproof. I haven't got the fuel pump yet, still shopping. Have you all experienced uneven fuel distribution with the mondo jets in the back and the stock sized in the front? Quote Link to comment Share on other sites More sharing options...
John Scott Posted February 4, 2006 Share Posted February 4, 2006 Have you all experienced uneven fuel distribution with the mondo jets in the back and the stock sized in the front? I always wondered this as well. V6 Holley carb was almost as long as my intake! Plugs were always on the rich side. Use was street so I appreciated the PV for driving around, ditto with my current 383. My NA drag buddies swear by the plugged pvs front and rear and square jetted. Road racing carbs generally have pvs front and rear square jetted. Always wanted to try square jetting with direct rather than progressive linkage, but never found the time. What's best with forced induction.. this is all way out of my league, so I'm outa here. John Quote Link to comment Share on other sites More sharing options...
Turbo Meister Posted February 5, 2006 Share Posted February 5, 2006 What brand are you using? I though you had a mechanical pump, or was that an earlier engine? John, Are you planning to build your own horsepower monster? I use the Aeromotive regulator and I've never had a mechanical pump. Hanns Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted February 5, 2006 Share Posted February 5, 2006 I am planning on using the Mallory pressure regulator and connecting the boost reference to my air box up stream of the carbs. This is where the float bowls get their positive pressure from and where the connection should be by my logic. The planned set up is L-6 Triple 45MM SK Carbs M62 Supercharger 12 psi of boost w/ intercooler. Malloy fuel pressure reg. 280zx distributor with no vacuum advance/ mech only. I wish there was more info on triple carb forced induction jetting. Quote Link to comment Share on other sites More sharing options...
John Scott Posted February 5, 2006 Share Posted February 5, 2006 John' date='Are you planning to build your own horsepower monster? I use the Aeromotive regulator and I've never had a mechanical pump. Hanns[/quote'] Re. the mechanical pump, too many forums, or more likely another rusty spot in my memory lol. No plans in the imeadiate future. Once you've had forced induction, you alway wonder what if, when you don't have it. I've been transfixed with your car since I first saw it. I'm taking notes on your fine car, Dr. Hunt and Silicon boy. My former neighbor has fabbed up a beautiful twin turbo, intercooled blow through, he's one hell of a welder, running into lots of trouble getting it to run right. Losing interest. Hmmmm. Quote Link to comment Share on other sites More sharing options...
John Scott Posted February 6, 2006 Share Posted February 6, 2006 I am planning on using the Mallory pressure regulator and connecting the boost reference to my air box up stream of the carbs. This is where the float bowls get their positive pressure from and where the connection should be by my logic. The planned set up is L-6 Triple 45MM SK Carbs M62 Supercharger 12 psi of boost w/ intercooler. Malloy fuel pressure reg. 280zx distributor with no vacuum advance/ mech only. I wish there was more info on triple carb forced induction jetting. If your carb box doesn't see vacuum when the throttle is closed you might not have any vacuum issues with the Mallory regulator. My carb hat had a similar port for referencing mechanical pump, but ran mine from manifold with the thought closing throttle butterflys, manifold would see vacuum sooner, create a quicker signal to the regulator. Throttle spring was strong enough to shut air, but would strongly recommend a relief valve. Before I had pressure relief valve, carb hat would stay pressurized, even when I let off. In my case after WOT, too much residual fuel pressure caused carb to run very rich at idle cruise, due to overflowing float bowls. Big return line, relief valve, check valve, with line from manifold, resolved this for me. A relief valve on your carb box might do the same. Read above posts if Mallory regulator still drops fuel pressure with vacuum. The booster check valve I found was on one of those cheesy HELP displays at the local autopart store. You'll need a pump capable of delivering xxpsi over boost. I used Mallory 140 (-8 lines, will fit) internal regulator set to wide open so pump can attain 22 or so max psi. Sam at century performance gave some tips with this pump. Quote Link to comment Share on other sites More sharing options...
Turbo Meister Posted February 6, 2006 Share Posted February 6, 2006 Have you all experienced uneven fuel distribution with the mondo jets in the back and the stock sized in the front? I run 81's in front with a PV. Don't even think of running the stock 70 primary jets unless you open the PVCR's way up and reduce the high speed airbleeds. Hanns Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted February 6, 2006 Author Share Posted February 6, 2006 Cool, I'll change that straight away, better to be rich than lean, I'll go 81's as well and leave the 100's in the back until I can get it on the dyno with a wideband. There are so many blow through turbo applications on the road today that I've seen. The most common seems to be Procharger folks. In reality it is the same as turbo, just that the boost is produced differently. If it works for them, then it'll work for anyone. Hanns is a book of knowledge and the more this info becomes available the better this site will be. Banks has alot of discussion about just how trick this carb is, however the nuances of the mods remain mostly hidden. I'll try it and If I'm not satisfied, I'll go C&S carb option, perhaps on alcohol. Quote Link to comment Share on other sites More sharing options...
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