[Chesterkv]

Just a quick reply. I'm in Cali, but live in a low requirement area - no treadmill test required. I might also be lucky enough to be able to register in a no-smog-requirement county/city.

As I see it, cams will worsen idle, hurting HC results, and pistons will hurt NOx results. But I don't think NOx is even measured on the basic test. Modern cats can do miracles. Engine tuning can help emissions. And honestly I'm considering leaving Cali for greener pastures, sadly due to the worsening politics and destruction of freedoms here.

Shouldn't a 264/264 combo be not too bad for idle and emissions? I'm not sure where to look into that. More research!

Dude,


Oregon? You know they won't let you pump your own gas. Very creepy.



- Chester

 

[mr2tailbreaker]

just a note, I don't want to get ahead of myself. I might be able to do some CFD on the head/ports. Probably not very doable or worthwhile. I'll see. I would have to model the existing geometry pretty closely. However it might be possible to use it for qualitative estimates.

PS: probably not Oregon.

 

[rmeller]

...I had to pay the *%#@ $100 not to turn me in.

So the system does work.

 

[mr2tailbreaker]

Lol... but then they'll turn you in for playing the game! Hah. One more reason I wanna leave the state.

I'll have adjustable cam pullies, so maybe that can help with emissions? Reduce overlap (increase lobe separation)?

 

[rmeller]

If you have a boosted engine, maybe. If your induction is at atmospheric pressure, I doubt that there is enough blowthrough to make a difference.

 

[mr2tailbreaker]

If you have a boosted engine, maybe. If your induction is at atmospheric pressure, I doubt that there is enough blowthrough to make a difference.

So you are suggesting the cams shouldn't be much problem either way? Or that something more than overlap is the main source of emissions problem?

I would certainly assume that higher overlap will put more HC into the exhaust. And so reducing overlap should help. Unless you mean only at idle and fast idle? I imagine higher duration with minimized overlap should not cause too much trouble for emissions. Perhaps more carbon monoxide?

I'm speculating but I believe advancing the EVO event would hurt power but probably make little difference to emissions at idle. Intake seems more important, and I imagine retarded IVC could cause flow reversion back into the intake, possibly causing metering problems? Examining these two conditions because that's what's needed to increase lobe separation (decrease overlap).

 

[rmeller]

In an NA engine, the exhaust manifold is usually at higher pressure than the intake manifold, and only resonance effects can invert that relationship. I can't say that blowthrough is impossible, but the intake pressure should not exceed atmosphere until the upstroke, long after the exhaust valve closes. If you have high HC in an NA engine, then it is because you have too much fuel, inefficient combustion, or an inefficient cat. The valve timing is not the problem unless it is so bad that it is interfering with combustion.

In a boosted engine, the intake is artificially pressurized above atmosphere, so if you leave both valves open, then charge will just blow across to the exhaust until you close one of them.

 

[mr2tailbreaker]

okay, so you're saying at idle this isn't a big problem? Because I assume you would agree that at high RPM's the exhaust is scavenging the intake charge into the chambers, and some gets into the exhaust. I see your logic generally, but exhaust pressure waves do come into play here. Average intake and exhaust manifold pressures are not necessarily the same as pressures at the valves/ports.

 

[rmeller]

That's what I am saying. Resonance is not going to be in play until you are in the upper RPM range, and until then, your exhaust is above atmospheric and your intake is below atmospheric.

 

[mr2tailbreaker]

But are you suggesting cams won't do much to hurt a sniffer test at low rpms? If that's not what you're saying, then what aspect will be hurting emissions?

 

[oldeskewltoy]

The goal is a reliable street car that spends 10-15% of its time doing leisure track days; and to get as close as possible to Billzilla's estimate of 160 crank hp that the stock ECU is able to handle, about a 40hp+ gain over stock. The basic targets right now are cams, head work, high compression pistons, and anything else that's worth doing while i'm in there. Ill probably add some monitoring/gauge systems - EGT, oil temp, and whatever else is worth it, especially as I plan to track the car regularly.

Right now my target budget is basically under $1500, but flexible to go higher (really dont want to). Hoping that will pretty much cover cams, pistons, and head work. Expecting to do all assembly work myself plus all inspection, plus whatever minor machine/hand work I can. I've already put a lot of spiff- and tune-up work into the engine. In fact, just replaced timing belt, tensioner and water pump. I have lots of spare parts from junk yards, but only one block and tranny.

So far I think I'm shooting for 10.3-11 for compression ratio, to keep things reliable, but please give me guidance on CR as I'm willing to go as high as 91 octane will reasonably take me. Chamber deshrouding and exhaust port polishing and port matching are the main goals for the head. Intake port will be more careful and particular. Also will upgrade, refurbish and more or less blueprint the head as needed. I have 2 heads - a higher mileage (assumed <200kmi) bluetop head from a yard that is in good shape, and the head that's on the car now, about 80kmi, which might be cracked...

I do the kind of head work you seek... the porting work I do I've had tested on a flowbench with proven gains. Typically as long as the head itself is in good rebuildable condition, a typical 4AGE port job with 3 angle and back cut runs about $800-$900.

Cams typically run about $600-$1000

Compression increase can come from multiple areas - pistons($360 for OEM set?), head machining($65-$100), block machining($65.-$120), thinner gasket($60-$90) or a combination of the 4.

So far you haven't replaced rings($130), bearings ($200) or any other gaskets or seals... and you are well over $1500.00

For $1500 you can give yourself a solid rebuild, to do an adequate performance build it will cost at least another $1000

 

[mr2tailbreaker]

So there is another MRLS track day coming up mid September that I think I want to shoot for. Right now I'm researching, attempting to resolve questions. There are a couple of key questions holding me up.

First, critically, how advisable is it to install new forged high compression pistons with nothing more than a cylinder honing(that is, without being able to bring the block to a machine shop)? The engine definitely has less than 90,000 miles on it, probably better. I'm guessing my new rings will be in a different location, so any wear lip will probably need to be broken somehow.

Second, I'm trying to settle on a static compression ratio. I think with a polished chamber and proper piston selection/preparation, I should be able to run at least 11 to 1, and perhaps up to 12 to 1. Something I was reading online suggested that Wiseco pistons underestimate actual static compression ratio a bit. Keep in mind I will be running 264 cams all around at most and 256 cams at least. Something I read suggested that effective compression ratio of 8.5 to 1 is optimal or a limit.

One last question I'm wondering about, not critical, is what cylinder is most likely to blow a head gasket.

 

[8ton]

#1. Whatever piston you chose will have a recommended piston to wall clearance. As long as you can fall into the spec then you can get away with a hone. With so little mileage, you should be OK. Also any honing past the BGB .2mm limit MUST be done with a Deck plate. There are a lot of naysayers on this one, but I have seen first hand that it is a must. Check it out yourself by measuring the bores (with a bore gage, not calipers!) with just the mains in place and again with the head torqued down.

#2 I am right around 11-1 with 264s. I would be worried about 12-1. Many of the aftermarket piston manufactures use the wrong size C.C. Some 35 others 39. stock is right around 36. Also look for a piston that doesn't have a sharp point to the dome. With your budget so tight, you could reach your compression goals with oem smallport pistons, a skimmed head and/or a .8mm HG. Actual Toyota ones have a heat barrier coating on the tops, which is nice. Stock replacement ones, Like the $90 set from rock auto, don't.

If you can get a Smallport setup, it would be the best 16v choice. it CAN be set up to use your stock electronics, but they will struggle.

One smog guy was going to turn me into the smog authorities because he noticed the pulley. I had to pay the *%#@ $100 not to turn me in.

All the good mechanics must have moved out there. 90% of the guys out here have trouble telling a DOHC from a v8. lol Unless it is painted bright yellow, they assume it is stock.

 

[mr2tailbreaker]

Thanks 8ton. Really appreciate the help as ill have a tight schedule to make Sept 15.

I think I'll err toward safety/reliability and shoot for a range of 10.8 -11.3:1. Pretty sure I want 264s all around. Just gotta be sure about which make of cams/pistons. Not sure about head skimming, especially if the Toyota ones are cast and not waaay less money, but surely not ruling it out.

I think my next big step will have to be pulling my motor apart to verify it is in the condition I hope. Crank size, oil squirters or no, bore, bearing and straightness conditions...

PS: you mean I should gauge the bore from the crank side with the head in place? Or I should use the deck plate to apply head bolt loads during checking?

 

[8ton]

PS: you mean I should gauge the bore from the crank side with the head in place?

Yes, If you want to be sure that a deck plate is needed. But it is, so just use one!

The smallport pistons are cast, but should be fine for your power goals. Used ones are usually around 100 a set, and there are aftermarket ones that are new for less than that. With a .8mm TRD HG you should be right around 10.8 and leave you $$ for cams, valvetrain and port work (which still cost money if you do it yourself!)
Keeping inside your $1500 budget will be tight, and I would cut the corner with the pistons and cams instead of gaskets and bearings.

 

[mr2tailbreaker]

If I did it again, I would do a 20v swap or mk1.5. Whats your smog situation?
Supertech also makes 18mm 11-1 pistons, in 81.5 and 82 mm os. You must remove and machine os pistons. For rings, bearings, gaskets (toyota) and machine work you are at or above 1500. On the right coast a valve job is around 125 for a stock 3angle or 200 for a performance one and around 35 to mill a head. Also I think OST's price list is around here somewhere, but I recall the full works being less than 1500. You could s a ve a few bucks deburing the cam valley yourself.

Ps. A 60cc syringe from tractor supply and a square of plexi with a small hole drilled in it will get you in the ball park for chamber work!

I don't follow the syringe/plexi comment...

Edit: Also don't understand what will need deburring in the cam valley?

 

[8ton]

Like this:

 

[mr2tailbreaker]

Don't forget about me when you are looking for parts.
I don't have a lot on my website but I can get you just about anything you could need.
If you do a big order I can probably swing a better deal too.

http://matrixgarage.com/

I can get a shelf piston from Wiseco with an 18mm wrist pin. They will be about 11:1 with a stock thickness HG. I can also get thicker and thinner gaskets.
Or you can go full custom pistons for a little more money.

Compression ratio will have no effect on reliability unless you knock in which case it will have a very rapid effect on reliability.
You don't sound like you are sure on cams. What power band are you looking for? 27Xs will give you a pretty steep power band with not a lot under 4K RPM.

This is a dyno graph of the poncams. I have to say these are pretty much the only cam that I get interest in. Of course I don't have many others advertised because these are so popular and such a great deal. Hard to beat in my book.

Yoshi, can you comment on the idle quality of the 27X cams? Will rpms be necessarily a lot higher than stock?

Based on what Poncam is supposedly about (drop-in, stock friendly), I assume stock valve springs should be ok for stock rev limits?

I'm interested in pushing rev limit to 8krpm if there's a simple enough way to get the ECU to allow it. I dont plan on running at or above 8krpm much at all.

PS: Anyone know if I should be considering Megasquirt? Can I run one and still pass CA emissions? Or, can i easily drop in the stock ECU for emissions check?


PPS: Just adding an unrelated log note - I believe i have late 240cc "yellow top" injectors (with the "split" nozzle) so I believe with proper fuel pressure, and a functioning stock engine managment, my fueling capabilities should be ok...

 

[mr2tailbreaker]

so I just finished reviewing some pictures from my oil pan swap. Best I can tell, with good confidence, I think I have the big con rods (20mm piston pins, which I assume means 42mm crank journals). Guessing I probably don't have oil squirters.

I hope those opens up my piston options...? Right now I'm leaning towards factory small port pistons. Cost savings and OEM quality sound appealing.

 

[8ton]

The casting flash catches and slows oil, and looser pieces could dislodge and float around your engine. I do all of the sharp edges on the head at the same time, because I don't like to cut my fingers when I am doing maintenance. It is easy to do, and takes around 45 minutes. I do the same to the block.

I am under the impression that aftermarket management, with a quality tune, would show all around gains on a stock engine. With what you plan to do, I would think that stock management will work, marginally, with some fiddling. Switching to MS would yield large gains. I have heard that you can build the megasquirt to plug into the stock harness, or there is microsquirt that can fit in your 'stock' ecu case. If they don't know, they can't tell you not to do it!