Lowering the cam lift point.

[Thxalot]

Anybody know of a solution to lower this point? I figure the Celica tuners should have found something by now. It's got to be possible, because several companies make engine CPUs for the S2000 which lower the cam lobe switch-over.-Burt

[Kissfan79]

Now THAT would be PHAT!!Jim

[Stang2Vibe]

Our site's resident Evil Geniuses have been pondering this one for at least a year now. Nothing reliable yet that I have heard of on this one.BTW---that wheel in your signature line looks eerily similar to the ASA KA3 wheels that I am planning to get for my Vibe.

[Thxalot]

Stang,Nice move on the KA3's. I've got the Superleggeras. They were kind of pricey (~$250/wheel) from Tire Rack, but IMO they are worth it. They are some of the lightest cast wheels around at 16lbs for the 17x8. I got them in the gun-metal grey color. Sort of hits a shade exactly in between the satellite and the charcoal body cladding.A quick check of http://wheelweights.net shows the 17x7.5 KA3s are 23.4lbs. However, I am sure you are getting them for a lot less dough. Where are you buying?-Burt

[TopObject]

Unichip is devoloping a Plug-N-Play performance chip for the 2ZZ engine as we speak. They are using Matrices as the beta testers, but the chip should be compatible with the Vibe's ECU.I believe with this chip you should be able to safely lower the lift point to 5500 RPM. This thread over at MO tells you everything you need to know. Its long, but just read through it, all your questions will be answered. Oh, and there should be a significant gain in HP as well.http://www.matrixowners.com/modules.php ... ht=unichip

[MadBill]

I see the last post in that thread is about 2 months old. Any idea where they are now on the chips?

[Stang2Vibe]

Probably still in development. I wonder what the price will be and what performance improvement they will be able to claim. I'm also curious as to how the GT engine will take to being pushed even further on the power envelope.quote:A quick check of http://wheelweights.net shows the 17x7.5 KA3s are 23.4lbs. However, I am sure you are getting them for a lot less dough. Where are you buying?-BurtThere were few places I found that carry them, really. My best bet so far was also through TireRack.com. They want $239 each for them (I want the chrome finish). I wonder if the weight quoted was for painted or chromed KA3's? Also wonder if there is a difference. And what to the painted aluminum stock 16's on the Vibe weigh, just for comparison's sake. Also, do you know anything else about ASA's wheels (quality, duribility, etc.)?

[goodvibe]

From what I've heard, you can only drop lift about 5% and its current crossover point is actually the optimum.

[Thxalot]

Seems like we've degenerated into two separate threads here. Well I've got something to say for both so here goes:Stang, I think the stock wheels are pretty close to 20 lbs. When I was putting on the new set, I took a moment to use the arms and shoulders scale. The stock set was clearly heavier than my OZ/Dunlop combo, but only by about 1/4. I think the wheelweights.net figures are painted unless otherwise specified. Some companies, like centerline, can get the chrome look without the 1-2lb. weight penalty by polishing an aluminum wheel. See if the ASAs are polished or dipped. I got my OZs from Tire Rack too. They don't have the greatest prices, but have terrific service. I really wanted to get my wheels hub-centered. Only the Tire Rack seems to ensure that. I drive at triple digit speeds often enough to warrant the added security of hub centering.Goodvibe,I find it very hard to believe that the current transition point is the optimum for HP. I have no doubts that it is the optimum compromise between making the most HP and getting good MPGs and the EPA's LEV status. The trouble with long lift durations at low RPM is the is overlap between the intake and exhaust valves. When the engine is in the high-lift mode at low RPM there is enough time to get a little bit of the unburnt air/fuel out through the exhaust port before it is totally closed. This leads to unburnt hydrocarbons in the exhaust, and bad emissions.Given the sharp spike in HP when the high-lift cam profile kicks in, you can rest assured that the engine would make more horsepower in the 5000-6000 RPM range with the high-lift cam engaged. You could probably just extrapolate the high-lift power curve to lower RPMs on a dyno chart. It'll fall off more steeply than the low-lift profile. The optimum tranision point (from a HP perspective) is the point where those two line meet.With the VTEC in my Del Sol, Honda found that intersection. There is no kick when the cams hit lift at 5500. The car just keeps pulling strong right through the transition. It is much smoother climbing up the revs than the Vibe is.-Burt

[TopObject]

From what I have heard development should be finished within the month, but we all know how these things have a tendancy of getting pushed back.I have also heard that lift cannot be lowered too far, but can be safely lowered to 5500 RPM. IMO this would be very nice. With where it's at right now you must make lightning fast shifts right at the red line to stay in lift.I think the price will be about $700 accoring to that thread.You can email this guy - jack@unichip.us - he is the program manager. Ask to be put on the mailing list and you will be notified when the chip is ready for purchase.

[MadBill]

I think Thxalot has it exactly right. I thought maybe the lift point was delayed as a marketing ploy, just so we would really "feel the technology at work" as it came in with a bang, but it might be an emissions/F.E. thing instead. Either way, it could only help performance to drop it at least 500 RPM, maybe 1,000. I'm sure anyone with the capability of altering it will take the time to dial in the perfect shift point, and also keep in mind the gear ratio splits so's it's easier to stay on the big lobes. (Hmm...I went for the base engine when I ordered my Frosty in Sept '02 because 1. I planned to spring for the "190 HP" supercharger kit for "~$2,500" as soon as it came out in "Jan/Feb" and 2. I didn't like the delayed lift point on the GT. Now I discover 1. The SC still isn't out for the manual Vibe, it's only 166 HP and in Canada the price is just under $6000 and 2. Someone's about to fix the lift point and add substantial horses as well! Wonder what my trade in would be on a (whoops, down to 173 HP!) '04 GT?)

[mu_ohio]

Bump because I'm interested.

[Stang2Vibe]

The '04 GT is only rated at 173 HP? What caused this change? Are our '03 GT's possibly overrated on HP?

[goodvibe]

Thxalot, I doubt MPG/LEV standards have anything to do with it as you would never see these RPM in a mpg run and the CAT/ecu could keep up with proper combustion. Monkeywrench has been doing a POWER FC tune on a 2zz. They lost power with a lower lift point with their tune compared to standard lift point but otherwise made significant gains especially between 5K and lift. Here's a link http://newcelica.org/forums/showthread. ... 705Perhaps without a proper tune of A/F ratio and timing, a lower lift point may show some gains but 6300rpm seems to be the correct lift point for an optimum set up. I havn't bought a CAI because I wont give up any low rpm power and especially driveability on the 2zz. The power fc tune would make me reconsider.

[Thxalot]

GoodVibe,Interesting and lively debate. Thanks for the link on the Power FC. I'm going to have to read that closely.As for MPG, the EPA has specific requirements during the driving. In fact they are so specific that there are portions where they use full throttle acceleration up to a certain speed (like say 60mph). Without instructions otherwise, the drivers must shift at redline for a full throttle run. Afterall, that is what the automatic trannies do. This is why car makers put those annoying shift lights in cars during the early 90's. They could get better EPA numbers by requiring an upshift sooner. With the 2ZZ, you can hit lift in 1st and 2nd before reaching 60mph.As for the emissions issue, you are definitely wrong there. Have a look at table 2 on page 3:http://www.c7performance.com/data/2zz_ge_article.pdfAn engine junky will see immediately, that when the engine is in lift, there is a much higher open valve overlap. In fact, the overlap is 55-98 degrees for the intake and exhaust valves, depending on valve timing. Before lift, the overlap is only 4-47 degrees. This means that the overlap during lift is 51 degrees greater than without lift.If I can remember back to my days as a mechanical engineer taking a combustion engines class, we can work this out in more specific terms. At 7000 rpm when the car is in lift, this 51 degrees is 1.2 milliseconds of overlap (51deg/360 deg per rev / 6000 rev per min *60 sec/min * 1000 millisec per sec).If we drop lift to 5000 rpm, the overlap of 51 degrees becomes 1.7 millisec. That is 40% more overlap. With that much time, you are guaranteed to get unburnt fuel cruising down the exhaust. Actually, you can figure out exactly how much makes it out if you knew the incoming air velocity. Just divide that by the distance between the valves (~10mm) for a rough estimate. I don't know the velocity, but I would bet that you'll find this time very comparable to the 1.4 milliseconds of overlap at 6000rpm.The cats can handle some unburnt HCs, but there is no way they can handle that much coming at them. If you look closely at the article, you'll see that the engineers met their objective of TLEV qualification. For even more proof about the way to set the lift point correctly, look at how the best Honda tuners do it:http://www.hondata.com/techk20vtecswitc ... lquote:Set the VTEC point to 7000 RPM and tune the low speed cam fuelling and ignition Set the VTEC point to 3000 RPM and tune the high speed cam camshaft. Plot the torque curves and set the VTEC point to the crossover RPM This method ensures a very smooth VTEC transition (some JR customers have complained their VTEC was not working when it in fact was)Which is exactly how I described it earlier. There is never a naturally occuring cliff in HP/torque for a given cam profile. If you dyno the 2zz properly, and adjust the lift point, there is a transitional RPM where the high lift and low lift torque curves intersect. That point is definitely south of 6000rpm. Lowering lift to the smooth transition point will result in more power in the 5000-6000 rpm range, if done correctly. I suspect the Power FC guys made the same mistake mentioned in hat first Hondata link. They probably lowered the lift point, but then used the fuel map and valve and spark timing for the low lift cam. They probably just need more testing on the dyno, and a more powerful ECU upgrade.Sorry if this got too technical. I guess it had to in order to make the proper arguments.-Burt

[goodvibe]

Actually, I hope your right. I would prefer a lower lift point as oppsed to raising the cutoff point.

[Thxalot]

Goodvibe,One more note on CAI. I don't have one either, but my reasons may be a little different from yours. I have messed with intake plumbing on cars I've owned, and they are tricky beasts.The intake lengths are specifically tuned by the manufacturers to induce a pumping effect at certain speeds. The physical phenomenon is known as a Helmholtz resonator, and basically the intake runner acts like a pipe organ producing a nice pressure peak at the cylinder head. Changing the length changes the frequency (i.e. inlet air velocity) at which the resonator effect takes place. If you change it too much, you can get to the opposite side of the standing wave and actually have the low pressure point at the intake valve.I suspect the change in resonance frequency may be the culprit behind the poor low-end torque you mentioned. Many high-end V8s use two different lengths of intake runners (like the BMW 4.4 liter and Caddy's Northstar for example). A long one at low-speeds to give some Helmholtz push, and a short one at high speeds to minimize restricition.Throw in the added noise of CAI and I'm pretty skeptical that a couple guys in a garage can do better than the real engineers/designers. I realize that the dyno results are pretty convincing, but there is a reason for that too. The biggest factor with CAI and a dyno is that the dyno is a static environment. Despite the fact that they often but a big fan in front of the car, that is hardly a subsitute for flying down a freeway at 60mph.The air temperature at the stock air inlet is dramatically different when there is tons of air rushing past the underside of the car. It's especially different from a stationary car indoors hooked up to a chasis dyno. This is why manufacturers have offered ram-air and hood scoops to boost performance, but have never bothered with a CAI type snorkel to get additional HP.On the other hand, the CAIs are usually less restrictive so they can offer small HP increases due to fewer pumping losses for the engine. I think the true measure of performance gain by CAI is shown in the dyno numbers for a short ram intake. Although I haven't measured inlet air temps at 60mph, I bet they are similar for stock and CAI intake setups.Just my $0.02-Burt

[goodvibe]

This intake goes even one step further with its rather restrictive nature with plenum below 3800 rpm to increase torque and response, then the butterfly flap opens and lets in lots of air. Your suspension is like mine except I'm using higher profile 225/50/16 on 7.5 wide wheels to keep a better ride. There might be a better performance set up but I couldn't be happier with this daily driver. I like go more than show.

[Thxalot]

Goodvibe,I'm with you all the way on this suspension. I call it more "dash" than "flash", but I like your "go" over "show" phrase too. The pro-kits and progress bar cost just under $300. I bought a jack, some stands, and a torque wrench for just over $100. After a full day of DIY, this car now drives like the cat's meow. I can't understand why they don't ship GTs from the factory with a setup like this. For small surface imperfections like cement freeway gaps, I think the ride is even better than stock. 1 second into any turn and everyone knows it handles much better than stock.I almost went with 18" wheels and stepped down to 17" for ride and weight reasons. With 16" you probably get more benefits on both fronts. The disadvantage is that you have an extra 1/2 inch of sidewall which rolls under during hard cornering. Of course you can always crank up the PSI when you are heading for the twisties. I run my Dunlops at 38 psi most of the time. Wear seems to be pretty even.Got any pics of your ride kicking about? I'm curious about the butterfly valve on the intake. I thought it opened up under wide open throttle no matter what the rpm. Maybe that is a poor man's version of variable intake runners. Do you know a good thread on this subject?-Burt

[goodvibe]

No but it is vacume operated but never opens below about 3800 rpm. On the Celica forum, they remove it for the intake sound at lower rpm without reported problems. I think our stock intakes work better in the lower rpms and removing the flap adversely effects initial throttle action.

[sharky_9901]

the butterfly valve opens when the motor is cold to suck in warm air from the motor, and when the motor is warmed up it closes. i also found documents on how to remove it, but cant find them. i think i got them off the newcelica site.

[dmitri]

thxalot u still got that GMD exhaust? email me: dmitristefaniwsky@yahoo.com

[goodvibe]

If you remove the butterfly, You'll have the low end torque of a cai plus bog and the top end of the stock intake plus maybe 1 hp. Unless you really, really, really like the sound of a more open intake why get the worst of 2 worlds.