Tony D

Solenoid... The EGR is disabled when the engine is cold. This is what the solenoid does. Until the engine reaches 120-130 degrees, EGR is disabled by the water temperature switch. On the 74's, there is a third gear switch, and a speed switch, AND a water temperature switch (vacuum switch that is thermally activated). The speed sensor and the transmission switch complete the circuit to let the EGR solenoid open to allow vacuum to be ported to the amplifier/diaphragm, and the thermal vacuum switch acts as a mechanical block until the engine is warmed. The amplified and non-amplified EGR's have different switching scenarios. The later 77/78 had a back pressure transducer and delay thingie in the hose for California to stop tip-in stumble inherent in the lean operating conditions of Cal Calibrated cars, the Fed calibrated cars were richer to begin with so they just had a thermal vacuum valve like on the earlier 74's. Basically, if you aren't pulling at least 2" Hg on the manifold, the EGR will not be open. So any sort of full load condition will stop it from recirculating. This is all from memory, but it all goes back to the fact that the cars had a plug if they didn't use a switch. What is the manufacture date on your car it is possible someone has swapped parts, you know!

Original Non-EGR cars (like non-USA) will not have the switch, they will have a plug. I forget what it is for, but there is another circuit it disables... Cold Start Valve is a thermotime and crank signal kind of thing. The 1975 EFI Bible shows the Water Temperature Switch, and does not tag it as California Only, but also shows in most of the diagrams and photos a PLUG in it's place---which I what I have seen on Non-Catalyst cars. (Home Market JDM L20E's had EGR from day one, they had stiffer regulations than California at the time!) There is a harness for it, and a function it does, but other than turning on the solenoid to allow EGR to work...hmmmmmm....

I agree, the big hulabaloo about eyebrowing the bores is not a 'NOT'. The heads WILL work, but it depends on how the dowels and head are positioned on the block wether or not the valves tag the tops of the bores or not. I have even seen early L24 engines with big-valve N42 heads on them where the valves 'self clearanced' against the block at original crankover, and then ran tens of thousands of miles before anyone found out the valves were (at one time) interfering with the block. It's more of a 'should' eyebrow the block statement, rather than a positive declarative sentence structure.... Always check interferences before assembly and determine what needs clearancing and what does not. Some may need it, some may not. Do it and you know you won't have a problem.

Rewiring the stock harness to work with the Megasquirt's EFI controlled relay to switch power on to the injectors is a REAL EASY hack on the stock harness. All the power wires to the injectors come in a big cable which is spliced to go to the individual injectors. On N/A cars, the resistor pack is the easiest place to make the switch as it comes from the battery in one cable, which you hook to your relay, and viola...done. Same for segregating and grouping the grounds for the MS to gate them. Spend some time with the factory wiring diagram, and it will become self-evident.

He does it because he drives a BMW...make no mistake, we all know what that means! LOL

Wasn't Cartech's more like 4X3 or 4X4? It seems squarish from what I remember, as opposed to the rectangular form of the 2X4 Extrusion.

They use a squirt bottle to spray methanol into hilborn injector setups to get the car started and that works... Once it's fired once, the atomization of the injectors will have the mix carried to the cylinders without much issue. Aluminum spacer will be more practical, I don't know where you're going to find machinable graphite that will withstand the vibrations without compressing or deforming. Phenolic might work, but with the close proximity to the headers, that's probably out as well. Aluminum is used OEM for a reason, cheap, easy to machine and form, and durable. Think on it a bit, it's easily obtainable as well!

I did get that cowl hood at the Yard Bryan was a whole $40. I got your message, been busy though. Next time I'm in PHX, I'll carry it along with me. Did you balance those reground cams before installing them, BTW?

Keep in mind, the turbo is the first stage of compression, the supercharger he is using was originally designed to feed 3.8L. With 7psi turbo boost and the fixed 1.5 ratio of the blower you end up with 18psi to the engine, if it all flowmatches. Thing is the turbo can be slightly to moderately undersized as it can overspeed to feed the blower, which in turn feeds the engine. All you do is externally gate the turbo if you run into backpressure issues on the exhaust side. But with the turbo being fed 3.0+ Liters of exhaust flow, boost threshold will be much lower than if it was a single-staged setup.

I have to agree, if you search my posts, drape forming is what I used to do windows a long time ago. I think I even described the 'oven' I made using several heat guns and an old electric oven thermostat. Get it all evenly heated, pick it up with tongs and gingerly drape it over you buck, if you get frisky, have an oversized 'die' to lay over it that will hold it tight to the form while it cools. Then trim and start over on another piece. I had the chance to pick up a vacuum forming setup from a friend, but wasn't interested at that time. It would have been good for parts, it was for making bubbletop skylights for vans (groovy, man!) and was about the right size for headlight covers. Though with some two-piece molds/bucks you might be able to drape it over a buck and press the B section over and make a passable headlight cover...cosmetically at least. I would still think vacuum forming would be the way to go there. Then again low pressure could work the same way to press the piece over a positive buck...pressure is only a relative thing when discussing vacuum....

Is that over the stock fenders, or the lightweight thin steel units that they used on the rally cars? Muahahahahaha!

For all those quick to dismiss 'rings' after only seeing a 10 psi rise, at sea level I have had engines with 180psi of compression smoke like a third-world mosquito-abatement fog generator under these same conditions! Oil control rings don't do a damn thing for compression, and L-Engines are notorious for weak oil control rings. Only problem is the 'clean plugs' testimony. When oil control rings are bad, you will foul the plugs if the leakage is bad enough. I had a stuck ring on my #5 cylinder some years ago, and ended up trying to kill the engine running it like hell and beating it with well over my normal 12-17 psi of boost. After that track day....my smoking ceased. So did my plug fouling problem in #5. If there is smoke in the exhaust, I guess my question would be 'how much oil are you consuming and under what driving conditions?' If is possible that you can have clean plugs and still be sucking down oil past the rings... My 75 runs through about a quart between 500 and 1000 miles but the plugs are clear and nice light tan. You see it occasionally, you smell it if you are following me, you may even get bits of oil to rustproof your car...but the car has 180psi of compression, dynos to 147 at the rear wheels, and has 225K+ miles on the engine. I don't worry about it, I don't worry what everybody says about it...it runs strong, quiet, and simply uses some oil. One day I may go in and install some valve guide seals because I bought some for it...but it's not imperative I do so. So how much oil are you consuming...I haven't seen any quantification. Just a complaint of smoke out the tailpipe. If you evacuate your PCV to the tailpipe, it can smoke there as well... I'd be curious to see what pressure is in the crankcase during the smoking excursions. Many times restricted breathing can cause the pressure buildup and cause leaks/smoking. A catch can in many cases simply adds adequate volume so that the flow of the blowby doesn't pressurize it to a point where it will cause a problem. One with a coalescing element (steel wool looking stuff) helps when there is too much evacuation and the velocity keeps oil vapors entrained in the air---the wool gives the oil something to stick to and drop out of the airstream.

Imagine the support demands of a multiple segmented head sold to the motoring public...even if they are 'seasoned'---I know guys who have done field work for 35 years and still can't figure out which end of a dial indicator is up. I could see it as a 'NASA' style endeavor. Send the whole engine in for service in a crate like they do with Cosworths and Ford Racing engines. The only service allowable is FACTORY service. Got a knock, pull it, send it in and install your backup. That is about the only way that setup would be feasible. I would not want to warranty anybody else working on what I assembled. Period. It's not the manufacturing costs, it's the after-sale service for the lifecycle of the product that makes these companies money (most companies these days)....

I think the HKS was concerned with straight flow through the carburettor venturis so as to keep them functioning similarly under boost as they would in N/A mode. I can see that the swirling may hinder the flow somewhat, but I think it's the 'unavoidable tradeoff' you get when packaging that much flow in such a small area. On an optimized industrial compressor, the discharge area for that size turbine wheel and that pressure/flow would be probably 10 to 100X what you have in the HKS plenum. And when you have space, you have residence time. The more time you have before making the next process, the more you can do. I suspect with the looks of it, they hit several angles to diffuse the air as much as possible before the main chamber---which is what industrial units do---some add flow straighteners in the channel before next stage of compression when a particularly tight bend/casting is used. As you can see from the links SHO posted, the SK Comp Turbo Box simply has a flat diffuser plate in the box from inlet...don't know how that compares feeding what looks like both ends instead of the three holes the HKS uses, it would seem like the middle carb would be lacking somewhat. My setup was similar but also allowed the air to come in from the bottom of the box, through through many bored holes in the baffle plate acting to diffuse the air somewhat (or so I thought at the time...) It's almost as if the additional plenum volume gave the air the opportunity to swirl--it seems very linear in the upper plenum chamber where the velocities are higher, even with the two bends entering. I wonder if some horizontal flat bars in the lower plenum (or maybe somewhat 'plus' shaped) about equal to bore's centerline and between cyles 2/3 & 4/5 would assist in breaking up the swirling... It's modeled now, I guess it's 'easy to try it' now! LOL

$2150...wow, makes me glad I found 2 crack free 240 types before I left Japan. I guess the 'used' ones are now worth half new price! WOO HOO! My bud sold off his spare. I have a cracked up RHD 75 Dash, I was figuring sending it to "Just Dashes" and then rotating them till I get all the cars done (75 and 77)---this way the cars aren't off the road for too long, just dash-swap time. When you take it out, fix all the wiring! Good Luck!

You are looking at around $35,000 to get set up to cast a BARE head. O.S. Gikken hasn't thought enough of it to replicate casting forms they already have, that may tell you something about the market for after-sale L-Engine heads... Lots of ifs, coulds, and maybes in that equation, but not a lot of consideration of hard facts of the marketplace. Hard does not begin to describe the effort. Bankrupting is more like it! You want a Worthwhile Long-Term Investment, buy after split shares of APD anywhere below $45 a share. Far better return than spending that kind of money to build a head that is not legal in any racing class, and therefore relegates it to street and off-class or pure mod classes.

Argh...

Check out Monzster's post on turbo plenum design. It may not be the flow of the manifold, but vorticies in the plenum that leads to the disparity in airflow. Sounds like CFD is what you want...to see where the problem may lie---and then get an idea how to best attack it! Good Luck.

Oh, and of course, the aim of helping Monzster out and maybe giving him a direction to go regarding his plenum design---'know where you came from' kind of knowledge. That was another reason. If you can see how HKS addressed the issues, then it may give you an idea how to tackle the same issue. There is no sense reinventing the wheel and wasting all that effort when a good functional example is right there in front of you! Hell, I have two Type 1 Plenums, one Type 2, and an SK Plenum....so I probably have a bit more to loose than most 'speculators' should I choose to sell my plenums after all this knowledge lets me make one that is better....right? The only reason I didn't give him the SK Comp Turbo Box (the second one AZCar 'doesn't know what type it is) was I don't have the baffle for the inside of it. My design was an HKS style external, with the SK Comp Turbo baffle and several diffusers on the bottom, as I couldn't figure out how to segregate the plenum like the HKS was, and because I never actually held it in my hands to look at it, didn't know about the baffling, and could only assume what they did. I mean I got a box, and if he wants to look at the baffling in the post SHO put up, he could probably model it handily and see if there is a flow difference. When we hook up to return the HKS units, I can bring my SK box, as well as my home made versions. Now, I'm curious to see the difference between my design and the simple 2X4 Box Extrusion most people seem happy to use (as well as the CARTECH plenum.) $1500 for a New HKS Type 2 Plenum...that's tasty! Price didn't go up that much since 1989...

Hmmmmm, lets see. They originally sold for $1000. They can now routinely be had on E-Bay for around $200-$250. Exactly how much cheaper do you want the part? Do you REALLY think that ANYONE will be able to replicate the box as Monzster has shown it for $250? If they can, MORE POWER TO THEM WHERE CAN I BUY MINE! "Devalue the plenums here in the USA".... I don't know how much you paid for yours, but if you're concerned that a plenum currently selling for $250 is 'expensive' you may want to consider another hobby. It was modeled precisely to determine it's efficacy at the job. Looks like it was very good at what it was designed to do. Curiously, due to the cost in 1987, I MADE MY OWN after spending several hours staring at one in a speed shop display case and making mental notes of placement and sizing and then replicating it as best I could do. Does that make me a bad guy? I doubt I impacted HKS's sales in 1987. Maybe I should give Monzster my homebuilt plenum to see how it compares? That one could be easily replicated by anyone with aluminum welding capabilities. What would that do to their value then? What if my scratchbuilt aluminum plenum performs similarly? Then why buy the HKS? Then again, who's going to make it for as cheap as you can buy one these days (even at half new cost, or 2X what they currently sell for?) The part is NO LONGER AVAILABLE from HKS. For EVERYONE'S best interest, it's best to have the information available for replication (IMO), and for evaluation against their own designs. It would be one thing if HKS was still producing them, but that hasn't happened for some years now. That someone overpaid with some intent of gouging another L-Owner, such is the RISK you take when you undertake entrepuenrial ventures. Sometimes you eat the bear, sometime the bear eats you. That's the way it goes. Sure, there are guys with fantasy prices on them posted right now (something like $650)---seems to me if someone looks at the flow photos posted they now know FOR SURE the box is WORTH the money, and that's it's most definately NOT (as I was once told) "Just an overpriced cast piece with a big price tag because someone's name is on it... you can build one out of extrusion for a heluva lot less!" Seems that statement has been blown out of the water. Now, anyone got a CARTECH plenum they want to submit to see how it flows? I got a 2X4 Aluminum extrusion surgebox we can model and laugh at... Debunking myths, adding to knowledge. That's what it's all about. And Monzster said it all in his post: "If someone wanted to knock off an HKS Plenum, don't you think they would have done so by now?" Sorry, that got to me. That is so wrongheaded. Sorry.

Read your epoxy curing instructions to determine if vacuum bagging will help you. In many cases, curing the epoxy under several psi of 'tension' will increase it's strength. This would be equivalent of say 6" Hg of vacuum in the bag. It helps remove entrained bubbles, etc. The epoxy directions will give you specific conditions under which the strength can be optimized (say cure at 3psi pressure and 180F for two hours). Many times a simple I/R heat lamp can provide all the heat you need. A thermocouple or thermal bulb on/in the curing 'box' can be linked to control the heat source to keep temperatures constant. I need to read some of these links when I have more time, it looks like good information to review.

The deed is done, MonZster is in posession of the Type 1 and Type 2 HKS Plenums for some reverse engineering and CFD to let us all know what the Old-School JDM guys were doing. It's going to be interesting to see what the results are, and what can be learned/relearned from these artifacts...kind of like an archaelogical dig! It may shed some 'new' light on the subject, and move the design in a different way, or it may be a case of us saying "they made 592 RWHP in spite of what they were using at the time!"

Ohhhh, those kits would make believers of some Flat-Top owners if they installed them and took the time to get the carbs calibrated properly... I'm gonna have to get to Autozone and snag me some of these kits...

Jeff, I'll be working at the Garrett R&D facility all this coming week (Lomita and Hawthorne), I PM'd you my celphone number, I can drop by the HKS plenums some time this week if you're interested. Give me a call and I can load them up...or if you're up to it, come on by the GroupZ meeting on Thursday Night (7pm) at Fuddruckers in Buena Park, and I can transfer them to you at that time. Curious to see what happens when you reverse engineer them! LOL

Yes, the 3/16 line is the return. If you are considering EFI, don't use that for the return, use one of the 1/4" vent lines, the small one will cause some fuel pressure control issues if used with even a stock EFI pump...