Alright, so I've been reading a bunch of these posts on performance cams. Seems most just bolt on a cam and think it's all they need to do. Lots of disappointments out there as to the performance of the cams installed. It's not just here, but on a lot of different sites. So I thought this would be a good kick around thread. I'm not going to include any math in this post, just opening a can of worms. Camshafts are seriously misunderstood. I'm no expert on the subject, but I have a decent understanding of how they affect my engines output. Most of what follows is simplified generalization.


So, here's a few pieces to consider for the people thinking of upgrading their camshaft. You'll need to increase your static compression ratio if you increase your cams duration. I know it's common knowledge, but some didn't get that memo. If you plan to drop in a cam with 20* more duration the effective compression drops significantly which cancels out whatever gains you may expect. That's not to say you will have gains, they're just not as much as expected. Let's say you want to pop on an RV cam, @265* duration with .430" lift, That 9.0-1 compression(static) that was 7.5-1 effective ratio drops to a 7.0-1 effective ratio. The effect comes from the intake valve closing 10* LATER. To make up for that loss the static compression needs to increase just a bit more than the loss of the effective ratio, say for a loss of .5 effective a gain of .6 or .7 static compression would be needed to make it up. This increase with the static compression to compensate for the cam would not necessitate an increase in the fuels octane rating or a decrease in cam timing. On the flipside, an increase in compression with the smaller, stock cam could. That's not to say you can ignore your ignition timing.
Since ignition timing has been mentioned here, it is also a factor in how the engine behaves with that new cam. The stock timing curves are not optimal for that cam profile. For those distributors with mechanical advance you would need to learn how to adjust the curve with spring rates and adjusting the max advance. In cases of big duration cams removing the vacuum advance is a consideration with tuning the mechanical to do all the work. But nobody really tunes distributors any more, most don't have a clue how to, so this issue is most likely mute.
Then there is the matter of fuel. This is really a big issue. The EFI cam handle certain changes in an engines tune, but those carbs are not so forgiving. If the plan is to change the cam plan on changing the carb as well. The 22R carb is not easily tuned, especially the secondary circuits. The 20R carb I have done extensive mods to, Bigger throttle plates and venturis with custom jetting. That little Aisin carb can do pretty well if you know how to do it. The Weber is quite tunable and really the way to go as far as down draft carbs go, but the Holley does well too. Both the Weber and Holley have all the parts you'd need for tuning. Of course you'd have to learn how to tune the carb or find someone that already has the experience.

All this can be said about external bolt-on equipment as well. My point is that there really is no such thing as a "bolt-on" performance accessory. Without the accompanying tuning for any upgrade parts the expected increases will fall a bit short. If the proper tuning isn't implemented, even on the mildest upgrades, serious engine damage can occur. If the proper tuning isn't implemented engine performance can actually decrease. Pay attention to the manufacturers recommendations for the parts you intend to install. If the manufacturer says the parts will "work with the stock carb/EFI get recommendations on what to do there to accommodate the parts needs, timing, fuel etc.. The whole "will work with stock whatever" just means 'it'll get by', not 'perform optimally'. 

All this just has to be said. I've read tons of threads on this, and so many complaints on disappointments from just bolting on a part. I'm picking on cams here because it's what I've been looking at lately. Not to mention the guy down the street that just bolted on a 290* cam on his stock carby 22R and can't understand why it barely runs.  I gave him a cam that I know does ok with the stock engine and helped him get the head/block interface smooth enough for a thinner MLS gasket for a bump in compression. See how that goes.

The whole thing was a generalization, applicable to just about any engine using a camshaft.
The specific specification that needs attention is the intake valve closing event, this is what controls the effective volume of the cylinder and the effective compression ratio. If the intake valve closes at BDC then the effective volume is the same as the static volume, bore X stroke. Since the cam doesn't close at BDC but some time after BDC the piston moves up in the cylinder reducing the effective volume. Using a cam that has 20* more duration will open 10* earlier and close 10* later giving the piston more upward travel before the intake valve closes reducing the effective volume of the cylinder and the effective compression ratio in the process.
So a cam with 220* of duration(total) that opens 20* BTDC will close 20* ABDC and with a static comp ratio of 9 to 1 might have an effective ratio of 8 to 1. Replace that cam with a 260 degree cam and the intake opening moves to 40* BTDC and closes at 40* ABDC, with the same static comp ratio of 9 to 1 the effective ratio drops to 7 to 1.
Adjusting the cam timing has the same affect on compression as well advancing the cam will increase you effective comp ratio, retarding the cam will reduce it.
The later the intake closes the greater the losses become as the geometry of the crank to rod angle increases the greater the piston travels up the cylinder per crank rotation degree. That 20* ABDC may only move the piston 1mm up the bore while the next 20* of rotation will move the piston 3mm, and the next 20* will move the piston 10mm up the cylinder, etc..
As for the specs on the stock cams, irrelevant for the purposes of this post as this is a general overview of cam/comp ratio relation. But if I remeber from the last time I looked it up, I've seen a LOT of profiles, the stock cam for the 22R is something like 221*.  Bumping that up to 268* is quite significant, and would require a decent bump in compression to be efficient.

Yes, I understand what you are doing there. As I said it is a generalization. Not even presenting the proper terms or any math into the mix, just starting a conversation. Feel free to introduce any info you like. I convey an idea for others to dwell upon, I find it works better when people do their own research than when it is just given to them. At least the people that really care. Last time I said 'dynamic compression' I was flamed on so badly I decided to stop saying anything, y'know, keep it to myself, be selfish. I said 'effective' as a stick to poke the bear.

Not sure what you meant by 9lbs, maybe 9 to 1 compression?

My first ever mod on any 'R' series engine was to pop a 20R head on a 22R block, which included a shave of .010". That raised the compression to around 10.5 to 1 and the engine ran GREAT! The issues I had were having to run 92 octane gas, available at that time, and back the ignition timing back to stock spec.. That was with a stock 22R cam, whatever the specs were I didn't know then, couldn't find the info in any of the BOOKS I had available. I've done a lot of mods on these engines and the compression isn't an issue with the proper prep, parts and tuning. I can tell you what the 20/22R doesn't like, that's to rev high. It can be done, but that's a different story.

The 'works with' was not about carb or EFI, but pointing to 'working' with stock fuel and ignition systems efficiently without any further tuning, "bolt on" being a fallacy. Just bolting on a set of headers without paying attention to the fuel has been known to cause some negative issues in some cases.

I'm no expert either, just have learned a few things that are typically unknown or ignored by the basic DIYer. I am still being a bit selfish I guess by just generalizing, but it's a can of worms, reach in and get your own squimy beast and bait your own hook kinda thing.

Here's a little bit off topic thought for you. Increasing valve size can actually be a detriment to engine output. Figure that one out.

Flamers? Introducing any idea new to people brings out the best in them.

As for knowing my schtuff, I have years of experience and have built countless powerplants, but I still don't claim to know all that much. I don't really say much either, but I will share when observe an issue that I can shed some light on.

I think all the speculation on cams is fun, but the proof is in the seat of the pants results.  I ran the 20/22 hybrid with a stock cam and adjustable cam gear, good tune.  It was pretty fun. 

Now I have a 20r with the 22re performance 282 cam.  The head is pretty stock except for mild smoothing, equalizing the size of the intake ports and gasket matching. I didn't go nuts with this I was very conservative.  I run a fairly well dialed weber 32/36 on it.  I still need to tweak my jets a little; there is a small gulp when I hit the secondary which tells me I need a bit more fuel from the secondary idle jet.  It gets 17-20 mpg these days while at the same time accelerating and pulling hills better than any 22r/re or 20r I have had including my hybrid.  I even pulled ahead of a 3RZ with it on a highway grade near here.  I was pretty proud of my handy work that day .


This cam is intended more for a street truck according to Jim, but I run 32" tires and 5.29 gears so the truck feels plenty light on it's feet for a loaded down 4x4. I'm sure this is part of the success.

The overall balance and build of the vehicle comes into play for sure.  For a more strung out cam I think the truck really needs to own it's tires, not the other way around.  Gearing and tire size is very important in regards to cam choice and the tune is critical to seeing the results from a cam.

Anyway, Jim Putney knows his stuff for sure when it comes to 22r cams and I am very happy with his 282 grind in my carbed 20r.  I'd like to see more well documented seat of the pants impressions on the cams available and more guys really reaching for the good state of tune.  Distributor recurve is the next logical step and I'd like to see or maybe try some of that.


Seems like life is too busy right now but if I get there I'll post my experiences.

I've been looking for the stock cam specs for the 20/22R. All I have found that even comes close is a duration of 193* and .393" lift. I'm thinking the 193* duration is measured at 1mm(.040"). That would probably put the total duration @215*+/-. I would hate to think the total duration would be 193*. Anybody have info to confirm or deny this?

I have not been able to absolutely see Toyota factory documentation on the 22R/RE cam.  I have looked for years.

It seems there are different numbers that are posted on the web?

From my research the Toyota factory stock 22R and 22RE are the same profile.

This is the best I can find.... and it may not be correct?

Gross Valve Lift - .398” – Intake
Gross Valve Lift - .385” – Exhaust
Duration @ .050 – 210 – Intake
Duration @ .050 – 210 – Exhaust
Max Lobe Lift - .273” – Intake
Max Lobe Lift - .264” – Exhaust
Lobe Separation – 110.0
Valve Lash - .008” Intake
Valve Lash - .012” Exhaust

Gnarls.

Yes, I understand what you are doing there. As I said it is a generalization. Not even presenting the proper terms or any math into the mix, just starting a conversation. Feel free to introduce any info you like. 

Hi sirdeuce,

I don't mind getting into the weeds, but they can get deep. 

You are close and on the right track, but just to clarify your numbers… In my example, at 220 degrees, the intake valve opens at 0, and the EXHAUST valve closes at 0 degrees.

Yes…Increasing the Static CR would be necessary if you are profiling a longer duration cam.
You want the Dynamic Compression Ratio to be between 6 and 9.  So with that  ** increase in duration, you would have to increase the static compression ratio to 11.4:1 to get a Dynamic Compression Ratio to 6.21

There are several cam profile specs that can change or affect the Dynamic and Cranking Compression numbers.

Here’s some example numbers as you described...

CR 9.4:1
220 degrees
Intake Opens 0 BTDC
Intake Closes 40 ABDC
Exhaust Opens 40 BBDC
Exhaust Closes 0 ATDC
Static Compression Ratio:  9.4:1
Dynamic CR: 6.97:1
Cranking Compress: 162psi

**CR:9.4:1
260 degrees
Intake Opens 20 BTDC
Intake Closes 60 ABDC
Exhaust Opens 60 BBDC
Exhaust Closes 20 ATDC
Static Compression Ratio:  9.4:1
Dynamic CR: 5.21:1
Cranking Compression: 107psi

Here are some numbers from actual cam specs for a 22RE...

Stock 22RE - Factory Specs
210/210 duration @ .050”
Valve Lift:  .398/.385
Lobe Separation: 110
Valve Lash:  .008”/.012”
Overlap:  2.5 degrees
Dynamic Comp. Ratio: 7.21
Theo/Cranking Compression: 170psi
Compression Ratio:  9.45:1
RPM Range: 1800 to 5400
Peak Torque: 144 lbs
Average Torque: 129
Peak HP: 114
Average HP: 87.4

Stock 22RE - Factory Specs+DT Header, 2” Exhaust
210/210 duration @ .050”
Valve Lift:  .398/.385
Lobe Separation: 110
Valve Lash:  .008”/.012”
Overlap:  2.5 degrees
Dynamic Comp. Ratio: 7.21
Theo/Cranking Compression: 170psi
Compression Ratio:  9.45:1
RPM Range: 1800 to 5400
Peak Torque: 148 lbs
Average Torque: 132
Peak HP: 117
Average HP: 89.8

Stock 22RE - CC252S Cam+DT Header, 2” Exhaust
214/214 duration @ .050”
Valve Lift:  .420/.420
Lobe Separation: 110
Valve Lash:  .010”/.010”
Overlap:  3.1 degrees
Dynamic Comp. Ratio: 7.21
Theo/Cranking Compression – 170psi
Compression Ratio:  9.45:1
RPM Range: 1800 to 5400
Peak Torque: 153 lbs
Average Torque: 136
Peak HP: 119
Average: 91.9

Stock 22RE - EB261C Cam+DT Header, 2” Exhaust
222/222 duration @ .050”
Valve Lift:  .409/.409
Lobe Separation: 110
Valve Lash:  .007”/.009”
Overlap:  5.3 degrees
Dynamic Comp. Ratio: 6.73
Theo/Cranking Compression: 154psi
Compression Ratio:  9.45:1
RPM Range: 1800 to 5400
Peak Torque: 149 lbs
Average Torque: 131
Peak HP: 125
Average HP: 90.3

Stock 22RE - Schneider 244-50F EFI Cam+DT Header, 2” Exhaust
202/216 duration @ .050”
Valve Lift:  .415/.429
Lobe Separation: 112
Valve Lash:  .008”/.010”
Overlap:  2.1degrees
Dynamic Comp. Ratio: 7.45
Theo/Cranking Compression: 178psi
Compression Ratio:  9.45:1
RPM Range: 1800 to 5400
Peak Torque: 155 lbs
Average Torque: 137
Peak HP: 120
Average HP: 92.9

Gnarls.

The 'works with' was not about carb or EFI, but pointing to 'working' with stock fuel and ignition systems efficiently without any further tuning, "bolt on" being a fallacy. Just bolting on a set of headers without paying attention to the fuel has been known to cause some negative issues in some cases.

I understand your point and everyone has a different experience.

Here’s one of mine…

My 1985 22R, stock engine.  I installed a Doug Thorley header, 2” exhaust, deleted the cat, added a high flow turbo muffler.   The throttle response and power increase was VERY noticeable.

Because I figured the engine needed more air going in, so I did a simple modification just to see what the results would be.  The increase again was noticeable.

Here’s my Double Gnarly Air Filter Mod:

I stacked two stock paper air filters, extended center bolt, and cut and extended the breather tube to the rocker cover.

The difference was night and day.  Before I did NOT use 5th gear.  After the header and the air filter mod, I could do 80 MPH in 5th gear at about 3100 RPMs.

The spark plugs looked perfect and I averaged 20 MPG.

Gnarls.

Yeah, the #s on Schneiders site are different than what I posted, but I got the posted #s off the cam card I have with the cam.

When I build my 2.6 liter 22R the cam I'm looking at is WEB cams 391 grind. Not sure how that one will work, but I'm more or less after the valve lift.
The Schneider cam I mentioned before does look good, but I've heard nothing good about it, most of what I have heard is due to just throwing it in a stock engine. It's a reason I started this commentary, cams going into stock engines. Some of the cams available do a decent job, but just a little bit of extra attention to the tuning can go a long way.

That engine is not going to be anywhere near stock, Modded 20R head and 22R EFI mani to match. Stand alone electronics. Just working on building the budget for it now.

We're getting a little off topic with this.

Effects of cam duration on compression. Not build plans.

But we have looked at the main idea. Somewhere along the line the subject of ramp profile, overlap, timing or any other camshaft characteristic that might bring up questions can be explored. Maybe it'll help someone look at alternatives to that 300* cam in a stock engine.

 Maybe someone can get a thread worthy of being a sticky. Most are like ' I installed this cam and it was awesome above 5000rpm, but it runs like sour owl crap until then', and all anybody say in response is 'Yore cam is two big'(purposely spelled incorrectly). I've seen a couple of comprehensive threads  out there, on sites I just stop by to peruse, but not much more than that. I just don't have the motivation to do an indepth explaination on any issues anymore. Maybe it's a waste of time, outside of one other guy, H8PVMNT, only 2 people seem to be interested in the sublect.

Maybe if he would post a simple what it is here? Maybe a light what's what. I don't need to call the guy, and I doubt he has the time to answer a thousand questions.

Don't get started on cam timing. You can time the cam/s to spec or for whatever your tune needs. It was kinda mentioned before as 'timing'.

Sorry to butt in,  I won't.