Get Lift at a Lower RPM?

[MadBill]

OK, we've got a ton of people here who do wiring wizardry for amps, DVDs, etc., right? And no-one seems to have figured out how to tweak the ECU to alter the "Lift" engagement RPM. So how tough can it be to jumper the wiring to the solenoid that controls oil flow to the lift mechanism to allow manual control? It would maybe just take a grounding switch wired in parallel, or a second source of 12 v. to the solenoid, or...? With such a set up, once you were over 6,000 RPM in 1st on a banzai run, you could flip the switch, thereby ensuring that if the revs dropped to say 5,700 -5,800 after a shift, lift would remain engaged, giving a worthwhile boost in acceleration.How about it? Will someone take up the challenge? (Or, more likely, explain why it's a dumb-(removed)/impossible idea...)

[joatmon]

http://forums.genvibe.com/zero...m.jpg is a pinout of the ECU, the service manual calls the appropriate connector "C1" but in that jpeg it is labbelled as "E3"There's a connector on the engine for a "Camshaft Postiion (CMP) Actuator Solenoid Valve" that has two wiresYellow - CMP Actuator Positive ECU E3 Pin 14Black w/ Yellow - CMP Actuator Negative ECU E3 Pin 15You could probably measure the signals on those wires and see what they do in and out of lift, simulate those values to force lift.There is also a connector for a "Camshaft Position (CMP) sensor" which might be a signal back to the ECU to let it know if the cam is in lift or non-lift mode. Black - Camshaft Position Input ECU E3 Pin 26White - Sensor Ground ECU E3 Pin 34 (shared with Crankshaft Position Sensor ground at ECU)Going into lift when the ECU didn't think it should might freak it out to the point where it shuts it all down.There was some discussion, perhaps in one of the unichip threads, about lowering the lift engagement point, I can't remember why there was a lower limit, something about too many valves open at the same time or something like that

[Smokin' Rubber]

Hmmmm it sounds like it might be possible altho it would be alot of work I'm sure to figure out how to do it with the stock ECU. I think the easiest way to do it (if you you got that kinda money) is to buy a new stand alone programmable ECU like the Apexi one. I'm sure that would allow you to alter the cam positioning changes based on RPM's.

[satur9]

if you learn how to drive it right you can almost always land in lift.

[Smokin' Rubber]

Hehe true Satur, very true I usually don't have a problem with leaving lift if I power shift. Also, I'm not sure lift would benefit us as much at lower RPM's

[theimportscene]

i have a buddy w/ a RSX-S for which he got the Hondata #4 reflash... this raised his rev limit to ~8K and lowered his lift by about 500rpms... this pretty much ensures he stays in lift once he hits it in 1st gear... TRD shoud do something like this w/ your guys' 2ZZs...

[Stang2Vibe]

Quote, originally posted by MadBill »How about it? Will someone take up the challenge? (Or, more likely, explain why it's a dumb-(removed)/impossible idea...) Well MadBill, I think that the biggest problem with your suggestion is not that it is an impossible idea, but that some dumbass like myself could wire up that solenoid to a dash switch and then forget to shut it off. Or curiosity would get the better of me and a long list of "what would happen if I..." scenerios would come into my head. It would be like "well, if I get a big power boost when I flip this switch at 6000 rpms, then what would happen if I flipped it at 3000 rpms"? Or, "I wonder what would happen if I tried to start the car with the switch flipped"? See what I mean? My curiosity or forgetfulness would most likely lead to my blowing up my engine. There's a reason why that lift is set to engage within a certain range, though we don't seem to know what that reason is. I bet that we could probably expand that range a little, but going too far beyond it will lead to big problems.

[Smokin' Rubber]

Come on you know you want lift when you turn the key Stang for those fast getaways hehe. I think the reason it is at ~6,000 rpm's is because any lower would not help as much. Having the exhaust and intake valves open more and for a longer period of time help significantly more at higher rpm's. At low rpm's it might even cause your engine to lose a bit of power (not certain but would seem likely). The lowest I would put it is maybe 5,200 rpms or 5,500

[MadBill]

That's right, Smokin. If you put a long duration, high lift cam or cams in an engine in place of stock, the torque curve is shifted to a higher RPM range. I installed a factory high performance cam in my 327 c.i. Chevy II many years ago, It had a 3.08:1 axle and a close-ratio 4 speed and although the cam added a ton of high RPM power, it became a total slug up to ~ 30 MPH in first gear, due to the useful torque band moving up about 1,500 RPM. For the Vibe/Matrix, theorectically the factory would map out the power curve for the engine up to say 7,000 RPM using just the low lift cams, then do a second curve from maybe 4,000 to 8,000 with lift engaged. Then they would program lift to come in at the lowest RPM where the high lift cams made more power. The way it feels though, it's like they delayed the engagment 500 to 1,000 RPM, so that when lift does engage there's a big spike of power to really get your attention, rather than a smooth "hand-off" that would actually give better acceleration. So, not only would a slightly lower engagment RPM make it easier to stay in lift during a run up through the gears, it would also make more power sooner any time you accelerated through the 5,000 -6,000 RPM band.I think Stang just doesn't trust himself not to flip the Lift switch to see what happens at low RPM! There's no way anything could break; the worst that could happen is that there wouldn't be enough oil pressure to keep the lock pins engaged, so lift wouldn't engage. The best might be a wonderful lumpy, bad-(removed) idle...I'd try it myself in a heartbeat if I had a GT! Honest...

[Smokin' Rubber]

Quote, originally posted by MadBill »I'd try it myself in a heartbeat if I had a GT! Honest... Well if ya got some extra money lying around heheAnd as for what you were saying about the torque curves... I saw a diagram that show'd the tq for both the high profile cam and the low profile cam and they showed the intersection where they switched off. It looked like it was basically at the best place to switch to the high profile cam because it only switches when the lower profile cam is generating less torque than the high profil one does. So theoretically they made the cam change at the optimal rpm's because any lower and the "lift" cam would actually be generating less torque than the lower profile cam.

[MadBill]

Well, that's the way it should be all right, Smokin', but it sure seems like it's delayed 500 RPM or more... (Hmmm...just think how it would feel to have a manual override and engage lift at say 7,500 RPM!)

[Smokin' Rubber]

Lol one word..... *CHIRP!* hehe

[Jahntassa]

In my research to get a computer piggyback like Apexi has for the VTEC engines, it seems the VVTL-i uses more sensory inputs to make it work, including oil pressure, and other mechanical sensors. Not sure if it's true, but there seems to be more to VVTL-i than what's thought...

[MadBill]

Well, that might complicate things a bit...

[Smokin' Rubber]

Well I think you are paritally right Jahn. I think that the lift pins that lock the rocker arms (the valves basically) in the "lift" position have a governor (a little spinning thing that generates oil pressure similar to the governors in an auto transmision that allow it to shift). The governor probably spins at whatever RPM's the engine is at, and is designed to create a certain amount of pressure at 6,200 ish rpms which allows the pins to temporarily lock into position. Or something along that line.It maybe be mechanically impossible to force the engine into lift. You may need to get a oil pressure regulator with an electic compressor hooked up to the lift simulate device that would also be able to control the cam engagement. As for the delay in the lift that you were talking about Bill, the governor could be partially responsible for that. Maybe the engine doesn't switch to lift based on RPm's and instead switches based on oil pressure. That would mean that minor variations in the governor and how effective it is in each car (since they aren't all completely identical) could effect what RPM's lift appears to engage at.

[MadBill]

Hmmm... Sounds a little too imprecise! The pressure would be affected a lot by oil viscosity, so cold oil or a crankcase full of 50 weight would cause drastic shifts in the lift point. I'm sure that ultimately there must be an ECU-controlled solenoid that admits oil pressure to the pins, but there may well be several "enablers" required before it does so. (e.g., engine temperature plus a certain minumum oil presure, plus... ??)

[MadBill]

This just in!Our Matrix cousins have also been beating this lift thing to death, and they say the Celica gang have controllers to lower the Lift point to an optimum 5,800 RPM:http://www.matrixowners.com/mo...art=0

[Smokin' Rubber]

Hmm interesting find Bill, altho after looking at the dyno's of the two cars (the 03 and 04 matrix's with 6,200 and 6,600 lift rpms respectively) I came to think that raising or lowering the lift point is for the most part pointless.If you look closely at the dyno you will see that at 6,600 rpms with the 04's lift engages it has only slightly less hp than the 03's which had engaged 400 rpm's earlier. Then by 7,000 rpm's the 04 has more hp than the 03. In addition to that having the lift 400 rpms earlier only increased the overall horsepower by 0.8 and the overall tq by 0.5 lowering lift another 400 rpms from 6200 to 5800 probably would yeild even less extra hp.So it seems rather pointless to lower the lift point. Yes when you shift you might still be in lift, but it won't help acceleration that much by the looks of it

[MadBill]

It may be up for discussion on the '03, but it appears for some reason, lift is raised to 6,600 for '04 GTs. Given the huge torque jump at the lift point, vs. the relatively smooth low lift torque curve below, and high lift above, for sure it has to lose performance compared to "filling in the valley" by kicking in sooner! (Visualize extending the high lift torque curve downwards in a smooth arc until it intersects the low lift curve, somewhere around 6,000)

[Smokin' Rubber]

Very true Bill, lowering the lift point would help to smooth out acceleration and make the car more stable under heavy acceleration. I think the only problem with that would be just that lift would feel too smooth lol, if that makes any sense. It would be less fun revving it up to 5,800 rpms and hitting lift because the kick would be gone, replaced by a more smooth transition. Granted it would sound good and I'm sure it would perform slightly better (more noticably in higher gears such as 5th, lift may help push harder)

[MadBill]

Here's a site explaining the lift mechanism in excellent detail. Regardless of what sensors/inputs are consulted, it looks like lift is actually engaged simply by closing an oil drainback valve, thus causing a pressure rise in the sytem to move the locking pins:http://www.billzilla.org/vvtvtec3.htm

[Smokin' Rubber]

Yep, once the engine hits a certain RPM there is specialized oil valve type mechanism in the engine that turns on (or off rather I suppose) creating pressure (like Bill said) and forces the locking pins into their forward position under the rocker arm. Supposedly some of the factors for lift engagement include, heat (engine has to be a certain temp), load (slope of surface, amount the accelerator is depressed), as well as RPM's obviously.