http://v8buick.com/attachment.php?attachmentid=150309&stc=1&thumb=1&d=1254261582 Jim, I was wondering what the benefits of your individual intake runner system is as opposed to using an open plenum, since it is under positive pressure.
If you can visualize it, imagine water being drained down through the system and think of it in terms of a timed, pulsating system. Despite the pressure of the blower, it all still runs on the pressure differential between the inlet (blower outlet) and the cylinder, the same as N/A but just with additional pressure. So the flow characteristics aren't going to change just because of boost, you just get more of everything. Now, back in the days of the early flatheads where they ran all of the ports to a central plenum there was a serious problem with adjacent cylinders robbing each other of air/fuel mixture to the point that the first V8's actually made less power than the straight sixes of the day. As the intake manifolds evolved though we eventually got back to a single open plenum but the difference was that we used fairly long straight runners to do it. (The flatheads used a very narrow intake manifold in a 60 degree "V" engine configuration) These runners made all the difference, and what we've learned is that a runner with a volume roughly equal to the cylinder volume works very well. As for why, it's basically because of the cycling or pulsating nature of the flow, which piles the air up at the valve as a result of the inertia of the air column just in time for the valve to open again and take another gulp. Don't be mislead into thinking that this Ram Air effect does not apply to blown engines. It does. There is no change in the physics just because we double the pressure. Remember the original N/A engine runs on atmospheric pressure, or about 15 psi. Adding 8 more to that only makes the air more dense, it does not change it's basic behavior. So the blown engine benefits from all of the same things a N/A engine does. The extra pressure just gives a little more flexibility in how you can manage the flow. For instance, in a street engine where durability is a concern, more restrictive heads and lower lift cams can limit the top end while allowing an early pressure build up for a good flat torque curve. So to answer your question, basically the cross-ram runners are there to enhance bottom end and mid-range which is where the engine will be operating most of the time. They are large enough in cross section to not create much of a restriction in high rpm operation and may add some benefit there as well. ------------------------------ Here's another wrinkle for you guys. I was very dissatisfied with the available transmission options and began looking around to see what could be done. I decided it made sense to have a look at what was being done by the world's largest automaker (much as we would have quite naturally looked at GM offerings in the '70's) and ran across one very special automatic transmission used in the 2008 Lexus IS-F. This thing has 8 forward gears! Not only that, it will easily handle well over 400 hp, and the icing on the cake? It is extremely fast at 100 milliseconds for a gear change, which is second only to the Formula 1 cars' 50 millisecond speed (according to press releases). They don't come cheap, but I was able to acquire one for about 2 grand which appears to be about half the going junkyard price. This is the gearbox that is going behind my 340. All is not roses of course, I have to build an adapter (about 1/2 done) and it is shifted by an external electronic control so something of a challenge there. But I hope to have it on the road by next spring. JB
Thanks for the good explanation, it makes sense. Good luck with the tranny, you sure like a challenge!
Not so much, I just like results. I've made transmission adapters before so that's not anything new and I do have good equipment for doing that part of the job. Where it gets interesting is in the controls. I'd dearly love to avoid that part of the job but it ain't happening. JB
wait....so youre putting a lexus auto behind youre buick 340? sounds cool and alot of work also..but we all know youre the guy to do it :TU: 8 speed automatic! i'm sure some of us buick 300 and 250 guys may like one of these bellhousing adapters if youres proves successful I like more options
Below is a shot of the engine and one of the tranny. It's pretty beefy at a little over 200 lbs, but is narrow and compact, and the six 10mm converter bolts are a hint of it's strength. It should hold up well to this engine but the controls will be a big challenge. The adapter is coming along, but is requiring me to make some tooling to bore the center hole and get it all dialed in. I didn't have a print of the Buick bellhousing pattern and that has caused me more work but I expect this piece to be done in another week or two. That leaves the converter adapter. I could just redrill the one I made for the 5 speed but since that was made from the drop cut out of the MIC-6 plate used for the adapter (precision cast aluminum) I'm leaning more towards billet and won't order the material until I see how everything bolts up. JB
Yes, it is the original front cover and appears to be in pretty good shape other than a little erosion at a few spots on the mating flange. Shouldn't be enough to cause a problem though. I have to make up an oil pump drive for it to replace the distributor and for that I'm going to see if I can find some ball bearings that will fit the space available, or possibly needle at the bottom and roller at the top. I've ported the oil passages and am using a massaged booster plate with the stock 215 (straight) filter mount. Made some progress on the tranny adapter. The center hole is machined. Woo Hoo!! Almost had to eat my words though, on the second pass I began to doubt I could hit the mark with just one more. But, on the 3rd go around I had .0025" TIR, well under the .005" I had predicted. Part of the problem was that the locating pins were spreading the ring slightly causing the hole to go oval. That meant I had to jack around with the pins on the mill table at the same time I was fighting the x and y axis offsets, and to complicate it further, due to the bind one of the pins was moving just a smidgen every time I took the ring off the mill. Eventually though I got it all sorted out and on the last cut indicated .0002" TIR, which I was quite excited about. But then I thought I'd better put the other three bolts in and see if that made any difference and sure enough, as I tightened them I could feel the plate pull in ever so slightly. Just enough to add another half thou to my reading, putting it at .0007" TIR. RATS! Missed my target. But it wasn't by enough to make it worth another cut so I let it go. To put that in perspective, it means a center-to-center misalignment of .00035" which is about one tenth the thickness of a human hair. Any but the most high precision bearings will tolerate that much misalignment easily so I'm not going to worry about it. You may think this is overkill and that the flexplate will handle it and that is true. But if there is no misalignment to handle to start with everything works better. So next is drilling the holes for the transmission locating pins and bolts and then external clean-up. For that step I will clamp the ring to the bellhousing, dial it in to center, and stress it side to side to bring it to round like it is when mounted to the engine and then transfer the holes. JB
a tad more info on the transmission via wiki pedia AA80E 8 Speed Automatic Transmission Applications: 2007 LS 460 2008 GS 460 2008 Lexus IS-F 2009 Crown Majesta Gear ratios: 1 2 3 4 5 6 7 8 R 4.596:1 2.724:1 1.864:1 1.464:1 1.231:1 1.000:1 0.824:1 0.685:1 2.176:1 The AA80E becomes the world's first eight-speed automatic transmission. Smaller parts, a hydraulic circuit with fewer components allow the transmission to maintain the same size as the previous LS 430's unit. The aluminum die-cast case is 10% lighter, yet 30% more rigid, even with two additional gears and a 22% greater torque capacity the new transmission weighs 95 kg or 10% more than the previous unit. With new micro-laser technology gear tooth production tolerances have been reduced 50%. Aluminum has also replaced steel on gear tooth surfaces. Shift times are as low as 350 milliseconds or 41% faster than the previous LS 430's six-speed auto. The IS F and LS 460 (with sport package) use Sport Direct Shift (SPDS) which allows for faster shift times. The torque converter can lockup from 2nd to 6th gears.
Wikipedia isn't totally accurate but it's close. The lock up clutch works in every gear except 1st and reverse, and in the IS-F package it is used that way to give a favorable comparison to standard transmissions. The IS-F unit also comes with extra fast Linear Solenoids to further shorten shift times. That unit (which is the one I have) has a 300 millisecond shift time but 2/3 of that is eaten up by the control unit as processor time. So the actual interval used for physical shifting of gears is only a tenth of a second. That might not sound all that fast but apparently it is. I just don't have the actual numbers for a valid comparison, other than a quote that the transmissions in F1 cars shift in 50 milliseconds (.050 seconds). I figure that in manual mode I should be able to eliminate practically all of the processor delay by using a stand alone controller such as a PLC. In the stock system the controller (TCM) has to wait on the ECM which has a pretty heavy processor load, and both controllers have to process tables and such before shifting can occur even in manual mode. So I think there's a lot of room for improvement. JB
just curious on how youre going to get this thing to shift and you going with an aftermarket paddle shiffter? if so which?
Well, "Real men shift with a stick!" ;-) so that's the plan right now. Later on sometime when I upgrade the steering wheel I'll think about putting some push buttons on it, I know some people have done that. The IS-F used a transmission control module (TCM) that was separate from the ECM and that could be handy because it has the necessary innards to properly control the pulse width modulated shifter solenoids (no accumulators are used). But it takes commands from the ECM for shift timing and firmness which comes to it via CAN buss. The ECM could be used as well but would require spoofing of numerous inputs and outputs to keep it from operating in limp mode where you lose about half of your gears. Still, that's one option. I don't know what could be done to speed up manual mode or what sort of support Toyota might provide. Next option is Megasquirt (MS) which has CAN buss capability and should be able to communicate with the stock TCM. I use MS for engine control but the MS guys haven't been real helpful. They seem to expect everyone to become a programming guru like they are and figure it out yourself. Like many computer nerds they can't be bothered with you unless you are one of them. I understand that but it doesn't get me any results. Well, if I have to do that, I figure why not just go with an industrial Programmable Logic Controller (PLC) which is more robust to start with and uses more simplified and easier to understand ladder programming logic? They have the speed and power to handle the application and can also use CAN buss as well as other communication protocols. Right now this seems like the obvious choice but I'm allocating the entire winter to sorting this part out, and by next spring expect to have a solution in place. At this point I haven't ruled out any possibilities yet, but the search is on for a suitable PLC. JB
Amassing! All that electronic stuff is WAY over my head. Could you give us your reasons for going with an automatic instead of a manual.
It's been a long time coming. For sports car applications I've long felt that a manual gave better control of the car in all situations even though historically I drove one about as much as the other. I felt an automatic was about as out of place in a sports car as it would be on a motorcycle. But technology continues to advance, and for a number of years now I have felt that an automatic had the ability to be as good as a manual provided certain conditions were met. Regrettably the manufacturers and the aftermarket seemed to have no interest in meeting those conditions. But through incremental improvements I think we've finally gotten there. I was willing to try advancing this cause on my own using the old 2004r as a basis and still feel that might be possible. In fact that was the direction I was headed with it when I started looking at the Toyota units. So as a short rundown, the auto can make the actual shift faster than you or I can. (It needs help on the delay between command and shift, and it needs help on smooth downshifts) It eliminates the need for a clutch, but it needs help in decoupling the drivetrain on demand and re-engaging smoothly. It can ease the daily drive but needs help being in the gear you want when you want. And it needs help in engaging the next gear smoothly under all driving conditions. The new transmissions , with the aid of their electronic controls plus integration of engine controls can do most of these things well and have the potential to do all of them and more. So at this point the only real advantage that the manual box has is simplicity. And that is no small advantage. But nonetheless, with the amount of city driving that I now do I'm willing to deal with some complexity to get the results I want. I think it's possible to have the best of both worlds. To start with, the normal performance mode for this tranny is to use the lock up clutch in all gears except 1st in order to simulate the manual transmission driving experience. Reading that statement made me realize that for once this bunch of engineers were taking manual transmissions seriously and accepted that autos had serious shortcomings in the comparison. Fair enough, that is a major concession and a major step in the right direction. They added programming to enable throttle blip on downshift. Again, someone with a brain at the helm. Now obviously this function won't work on a retrofit without special provisions but it's evidence once again of right thinking in the design group. So those are a couple of good examples of the sort of things we can expect to find today if we turn over the right rocks. It's taken over 50 years for the industry to recognize the need and a new player to fix it but at long last they've caught on. I for one am more than willing to simply take advantage of it. By the way, the bellhousing plate is now complete except for cosmetic clean up and work has begun on the new converter plate, so assembly should occur within about a week, at which point the engine can go in the car. JB
