TimZ

The benefit to max power is negligible, as I've been pointing out. Max power was _never_ the point, though. Doubling the required pulsewidth for increased control at low loads was always the point, and if you are using large enough injectors to require PWs in the <2ms range at idle, the benefit here is huge. Being able to inject while the valve is open is nice, and directionally correct, but kind of beside the point. People always seem to get way too hung up on this. Injectors, even the new ones, get increasingly non-linear as you get near their min on-time. There is a zone (usually between ~1 and 1.5mS) where they still deliver fuel, but they tend to "glob" the fuel, so one cycle you get next to nothing and a few cycles later you get all the fuel that was missing the last few cycles, which is now way too much. Getting out of that range and into the meat of the linear part of the curve is essential to getting good drivability.

Yeah, you won't really see any difference in max power. If your injectors are big enough that your idle PWs end up in the sub-2mS range, doubling the PW by going full sequential will make a huge difference in fuel control at idle/low load. If you don't mind having the timing off by 360 degrees about half the time you could try just programming it for full sequential and simply not hooking up the cam sensor. That will work with a TEC3, but I'm not sure how the MS reacts.

Again - the key words here are "trying to". Once the required pulsewidth is significantly longer than the vale open time, then injecting on the "timed valve event" doesn't really do much. Typically the valve open period is 35 to 40% of the available 720 degree cycle, so it doesn't take that much to exceed it. This is why I mentioned that the timing is really only advantageous for low load conditions where the injector pulsewidth can fit inside the valve open period. Even given that, I think you'd be hard pressed to be able to tell the difference if the injectors were timed 360 degrees off.

Thanks, NewZed - this is how I understood Sequential Injection to work, and what I was basing my posts on.

I think this is where our visualizations are differing. My system's full sequential does indeed limit each cylinder to one squirt per 720 degrees and is timed to start at TDC of the intake stroke. That one squirt, however, can last up to the full 720 degrees if required. Does Megasquirt not allow this? Agreed - always better over beers!

I'm not a MS expert, but I don't think this is what I was referring to. I'm talking about running full sequential and simply not caring whether you were injecting on the "correct" phase or not. So each cylinder would get one twice-as-long pulse every other revolution. The phase relationship to the 4-stroke would stay the same for the duration of a given key cycle, but it would be "wrong" on roughly half the key cycles. And I'll bet you would never know the difference. I'll have to respectfully disagree. From this description it appears that you are confusing/conflating Sequential Injection with Direct Injection - they are not the same thing at all. While it is true that most sequential injection setups time the injection at TDC on the intake stroke, Sequential Injection has absolutely no requirement that the injection pulse has to finish before the intake valve closes. On the contrary at full load the injector pulsewidth is pretty much always longer than the valve open period. By a lot. As it turns out the timing of the beginning of the injector pulse is pretty much irrelevant at higher load/rpm. The only place it can make a difference at all is at low load, where the injector pulsewidth can be short enough to fit inside the valve open period, and even then the benefits of this timing are going to be extremely hard to detect for the purposes of anybody tuning their own MegaSquirt. The advantages of the longer pulsewidths at low load/idle, on the other hand, are pretty obvious. Again, respectfully disagree. First, E85 is not a good supporting example, since it requires roughly 30% more pulsewidth for a given lambda (i.e., it's easier). So yeah 1000cc injectors at 1 to 1.5mS isn't an issue. Try to run gasoline at that same lambda and you'll be looking at more like 0.75 mS pulsewidths which aren't so easy. I also don't see how 4 and 5bar rail pressures are going to help this situation - higher pressures typically drive lower pulsewidths for a given lambda and simultaneously don't help the injector achieve those short pulsewidths. Even if you can get injectors to work at 1 to 1.5mS PWs, you will always have better control over idle/low load fuel delivery if you can run at 2 to 3mS instead.

The key benefit for running sequential is that you get twice the injector pulsewidth. For those running large injectors this makes a HUGE difference in controllability of fuel delivery at idle and other low-load conditions. Also, you absolutely can run sequential without a cam sensor (if your controller will let you) - you'll just be on the wrong phase about half the time. This really doesn't make much difference in how the engine runs and you still get the advantage of increased injector pulsewidths.

^Exactly.^ I'm thinking this whole fuel pressure thing is a red herring - the two data points that were given were _not_ off by 5psi - the corrected value given for 10psi was right where it should have been, and the fuel pressure stated for 27psi boost was maybe 2psi too high. If you do the math for this, getting ~10AFR when you expected 11.5AFR requires ~15% increase in fuel delivery. 9.5AFR would take ~20% more fuel. The 2psi extra fuel pressure stated for 27psi will only account for about a 3% increase in fuel delivery. Even if you did have 5psi too much, it would only account for about a 7% increase.

A small return line won't cause issues on boost that aren't worse at idle, at least not by itself. Remember the return is a bypass that the regulator uses to drop pressure by bleeding fuel - the more fuel you need to flow and/or higher pressure you want to maintain, the less you have to dump through the return line. If the line were too small and you have a single pump running at constant speed you would be seeing too high pressures at idle LONG before seeing issues at boost. Do you have any other hardware in your fuel system, like a non-linear FPR (these were very popular in the 80's and 90's), a second pump on a Hobbs switch, Boost-a-pump, etc? Also, I'm assuming that when you say "stays that way" you mean that it stays too high until you are off boost, and then returns to normal. Is that correct? And... This doesn't sound right either. The 29-30 value sounds about right for idle with the pressure reference connected and the stock base fuel pressure (zero vaccuum) of 36.3psi (2.5 bar). The regulator's job is to always maintain a (in this case) 36.3psi difference between the fuel rail pressure and the intake manifold pressure. So, 10psi of boost should yield 47psi of fuel pressure (not 40). 65psi fuel pressure would be appropriate for 29psi of boost, but way too much for 10psi.

There's this one: http://forums.hybridz.org/topic/123487-compare-your-dyno-sheets-here/ Probably wouldn't hurt if it were to be stickied, but it's not that far back...

Not a problem. BTW - Ross at Quicktime mentioned that they just happen to be doing a run of the RB bellhousings right now, so it's easy for them to come up with a donor bell - If anyone was also thinking of doing this, now is a good time...

Ross from Quicktime called me today and they are going to make me a bellhousing, so from this point on they will know how to make one. However, for the time being it will be treated as a one-off. If they start getting a lot of requests, then they may make it into a part number...

I think you could probably get the engine side to bolt up by slotting the holes, but the clocking of the trans would be all wrong - the RB leans the other way in the engine bay, so if you bolted up the trans to that bellhousing on an L series the shifter would be pointing off to the side... Hopefully I'll find out in a couple of days whether they want to do this for me - it _might_ be helpful if any other interested parties called Holley's tech line and inquired about the same thing - if they make it a part number, then the rest of you won't have to pay extra for having a one-off made...

I'm having Liberty's Gears build me a new GM version T56 magnum, modified with an F-body tailhousing. I haven't decided just yet whether I'm going to just go with the narrow ratio gearset, or the wide ratio gearset modified with the 5th and 6th from the narrow trans... Also I checked my T5 before shipping its bellhousing out and it looks like the Quicktime bellhousing mated to the GM T56 should put the pilot shaft in about the same orientation as the Datsun trans (should protrude 0.52" vs the datsun 0.625"), so all I should need to do is get a modified pilot bushing for the crankshaft, instead of a custom input shaft or figuring out how to put a pilot bushing in the flywheel.

Well, I sent my Datsun T5 bellhousing off to Quicktime last Friday, so we'll see whether they are willing to make an L-series T56 bellhousing soon...

^^^^Xnke FTW - best advice so far^^^^ Regarding the exhaust manifold - I don't know what your class rules allow, but I would recommend emulating the Euro manifold's bellows arrangement by cutting the "regular" turbo manifold on the same spots that the Euro manifold has bellows, and weld in simple stainless slip joints - single or double slip, either will work. This will go a very long way towards eliminating the thermal expansion/warpage issues and you can do a better job of porting the runners if you like. Also totally agree on the intercooler - it's a non-moving part that drastically reduces your tendency to detonate, FFS. It's not rocket science to get a hose to not blow off a piece of tubing.

In general, this means the "GM" variant, not the "Ford" one. The Quicktime bellhousing is meant for the GM style - the Ford input shaft is shorter in addition to being a different spline configuration

The standard offering from Tremec for the Magnum is a wide ratio and a narrow ratio gearset wide ratio: 2.97 2.10 1.46 1.00 0.74 0.50 Narrow ratio: 2.66 1,78 1.30 1.00 0.80 0.63 That said - Liberty can mix and match ratios (at least for the overdrives) for a fee.

Agreed it's not cheap, but it should be a direct fit and it is SFI rated. Do you know which T56 you wanted to use? That bellhousing, mated to an F-Body T56 should put the shifter 30" back from the engine mounting surface, which should work out well for the Z's opening in the trans tunnel. Still have to figure out what to do for the pilot shaft - it looks like it would protrude about a half inch past that bellhousing, and I don't recall offhand if that's enough to reach the bushing in the crank. I'm thinking 510six's solution of pressing a bushing into the flywheel might be better than having to get a custom made input shaft...

Thanks! So I spoke with a Holley tech rep today (Holley owns Quicktime) and they did have both bolt patterns on file. He confirmed that they were close but not exact matches. The "closeness" is not necessarily helpful since they are close enough that you can't just drill two sets of holes - you'd have to slot a couple of them, which would kill the SFI rating. All is not lost, though - he talked to their shop foreman at Quicktime and he was willing to take a look. They are willing to make me a one-off for an extra $450, which isn't too terrible. They did say that in general they were interested in establishing more presence in the import world - not sure how much this particular setup will help, but they might make it into a product. I'll be sending them my T5 bellhousing for a reference shortly.

So - does anybody have definitive dimensions for the engine/bellhousing bolt patterns for RB vs L-series? I found this post where Austin shows the specs for the L, but haven't found the equivalent for the RB...

Yeah, Bubba is generally really helpful but I don't think he's actually done this mod himself. Kevin at The GearBox did all of the conversions that I know of. Yes the input and output shafts are larger, and I had gForce make me a custom input shaft that was the correct length and had the correct pilot shaft for the Datsun setup. Here's a link where I talked about it - broken links are fixed towards the end: http://forums.hybridz.org/index.php/topic/45954-t-5/ The GF T5 has been a really strong trans - I'm just thinking that it would be smarter to upgrade before I break it, and actually have a good trans to sell...

I'm looking at that option too, but it has its own issues - namely adding an adapter plate adds distance between the trans and the engine, which means you have to figure out how to get the input shaft to reach, both for spline and pilot shaft engagement. Also need to deal with shifter location - the adapter can help or hurt with this depending on the tailshaft housing configuration.

For the purposes of this post I'm mostly trying to figure out if anybody would follow if I were to blaze this trail. Seems like there are periodically people looking into a T56, and then it turns out to be a lot of one-off fabrication so they go another route. If there were a bellhousing available and Austin is already making a rear crossmember for the LS crowd, maybe it would be more palatable, maybe not, since the Quicktime bellhousings appear to be high quality, but not particularly cheap. I'm already running a gForce T5 and while it's been holding up, I'm currently quite a bit over it's 500lb-ft torque rating. The magnum is rated for 700lb-ft, which is likely pretty close to where I am at the flywheel but the 700lb-ft number appears to be pretty conservative, especially for a turbo car that will never hit that hard in 1st gear. If I'm going to replace my working GF T5, I want to go with something that's more of a known quantity.