Maximum lift to benefit 4AGE head

[yoshimitsuspeed]

There is a ton of misinformation out there about cams and the 4AGE head. I constantly have people coming to me thinking they need to run shim under bucket for any cam over 8mm lift or 9mm lift or going off of other information that they learned online. Or even worse spreading this misinformation to others. You can most certainly run more lift on stock 16v buckets. How much does partially depend on other factors of the cam.
But I digress. One claim I have encountered a lot lately is that an unported 16v will not benefit from more than 8mm lift.
I have known for some time that there is benefit to running more than 8mm lift even on a stock head but I don't have any good hard data on the subject which leaves my hands pretty tied when someone comes on insisting that anything more than that is a waste. Tonight I was able to have a little chat with TED components and I was going to have him send me some information to try to support the fact that any motor could benefit from more lift. When I told him that this was a fairly widespread view in the online communities he asked that I start a thread on the subject and that he would post more information.
Many of us have seen these graphs and discussions from when oldskewltoy and burdickjp graphed some flowbench results. I post these because they are easy to find but I have heard many people claim that there is no benefit to running cams with more than 8mm lift either because they had read it online or some even because they say they did flow bench or other testing themselves to prove this.



I will let him do most of the talking but one thing he did mention is that you can still benefit from running a cam with more lift than the plateau on a flowbench because the cam is only spending a small percentage of time beyond that point.
You can improve this by running a cam with longer dwell however it can still benefit you to run a little more lift than your flowbench plateau.
I will link him to this discussion and hope we hear back soon.

[jinx]

Cams are too complex a subject to "guess" at. What looks 'right' on paper, make suk in reality
Seen faaarrrr to many instances of that..... starting with my first ever camshaft swap in an import
Long story short, I finally wound up with an Isky(just as I was advised/warned from the start, by an experieced 3TC guru).
I was startled at the performance (no other changes)
As Ed Iskederian stated in his catalogue, " there are as many ways to shape a cam lobe, as there are ways to stretch a rubberband around your three fingers". Only the 'correct' shape mattered. Most grinders get it wrong, from my observation and lack r&d

A starion clubmember ran a popular Schnieder grind. He meticulously degreed every lobe. Eventually got Schnieder to acknowledge their goofup, agree and they sent him another grind, which checked out to his standards. The car picked up almost 100hp, dyno'd stock vs cam 1 vs cam 2 !

I personally will ONLY ever run the exact cam I've seen with PROVEN results on similar setups. Keep it simple

[oldeskewltoy]

Love your title... "Maximum lift to benefit 4AGE head" - standard valve, or O/S valve head???

Does it matter?


As jinx rightly points out it isn't just the lift

[yoshimitsuspeed]

The point of this thread is to talk about those variables.
I did say in my first post that many people believe that more than 8mm does nothing on an unported head. Now if you have gone with oversized valves before touching your ports then you need to straighten out your priorities.

This thread is largely in response to recent situations were vor example I have been talking to a potential customer who is insisting on running something like a 272 with something like 7.8mm lift and while I am trying to suggest that they not waste their time on such measly lift there are two other people telling them they won't gain anything from more lift and one of them insists they are a seasoned flow bencher or some such nonsense and so the customer looses interest in my cams and doesn't want to hear anything I have to say on the subject because they read somewhere online that his mostly stock largeport head will not benefit from any more lift and that it will only add more valvetrain wear with no benefit.
I know for a fact that this is not the case and since I don't have the data or experience to back that up personally I am fortunate enough to know people who do.
And yes it most definitely depends on the grind of the cam and how that cam ties into the build.

[oldeskewltoy]

I did say in my first post that many people believe that more than 8mm does nothing on an unported head.

What people?

Now if you have gone with oversized valves before touching your ports then you need to straighten out your priorities.

you might go with O/S valves and only minimal porting... to gain port velocity



above is an overlay from 2 flowbenches measuring 4AGE exhaust valves/ports, mine, and Jeff's. Although comparing them directly is a bit futile, his stock valve #s line up moderately at low lifts (2mm-4mm) to my #s, but note the O/S valve @ those numbers....

Now that is the exhaust side, but similar improvement on the intake side is likely. I'm not saying you would ONLY go with O/S valves, but you MIGHT go with just enough porting to gain both volume AND velocity... so you might go with O/S valves and only minimal porting... and a minimal duration cam, but I'd go with as much lift as possible... which in this case would be about 8 to 8.5mm of lift for about 212 @ .050" cam

[NH-hillbilly]

you might go with O/S valves and only minimal porting... to gain port velocity

off the shelf oversize valves for this motor are only available in 1.5mm larger intake, and 2mm larger exhaust, making it necessary to install oversize seats in the cylinder head. we already discussed this remember?

after you install a 2mm larger exhaust seat, your left with a giant step in the transition from the seat to the bowl area of the port. how do you "minimally" port that step out you have to open that entire port up to get everything happy.

exhaust ports on this cylinder head suck. short side radius is terrible.

[oldeskewltoy]

you might go with O/S valves and only minimal porting... to gain port velocity

off the shelf oversize valves for this motor are only available in 1.5mm larger intake, and 2mm larger exhaust, making it necessary to install oversize seats in the cylinder head. we already discussed this remember?

after you install a 2mm larger exhaust seat, your left with a giant step in the transition from the seat to the bowl area of the port. how do you "minimally" port that step out you have to open that entire port up to get everything happy.

exhaust ports on this cylinder head suck. short side radius is terrible.

Blend bowl to seat.... keep port relatively alone





There are far worse short radii... for example the Nissan SR20

[NH-hillbilly]

walk me through that pic a bit, I cant make sense of it. there are no valve seats installed, (or are there?) and the pocket isn't large enough to accommodate a seat is it? looks like a rough cut before the pocket gets brought "on size"

i'm not arguing with you so please lets do our best to not get fired up.

i did some port work on sr20 recently and I honestly don't remember it being that horrible. Is it possible that early sr20 heads differed from later ones?

same goes for 4age heads, is it possible that early model heads differed from later model heads slightly? the 4age head I did was terrible. the short side was literally a wall.

[oldeskewltoy]

walk me through that pic a bit, I cant make sense of it. there are no valve seats installed, (or are there?) and the pocket isn't large enough to accommodate a seat is it? looks like a rough cut before the pocket gets brought "on size"

i'm not arguing with you so please lets do our best to not get fired up.

i did some port work on sr20 recently and I honestly don't remember it being that horrible. Is it possible that early sr20 heads differed from later ones?

same goes for 4age heads, is it possible that early model heads differed from later model heads slightly? the 4age head I did was terrible. the short side was literally a wall.

those are O/S seats. seat on right has a basic shape, seat on left has not been machined yet

As to the SR20, my current client has a VE, and those short radii are poor, too short




As to the 4AG exhaust short radius




Or....



*edited content* from showing many castings to just these two

[ss4nemis]

What is the unit of measure for lift on the 3rd graph?

Sent from my LG-LS970 using Tapatalk

[sirdeuce]

I always thought the limiting factor to the amount of lift possible in a 4AGE was the follower and or spring used. As far as lift/flow? Excessive lift is basically just wasted, the port will only flow what it will flow. So I'd say on a head that maxes flow at 8.5mm wouldn't benefit by a 10mm lift cam. I'd make my lift limit on the mechanical parameters in the valvetrain and piston/valve interface.

[oldeskewltoy]

Excessive lift is basically just wasted, the port will only flow what it will flow. So I'd say on a head that maxes flow at 8.5mm wouldn't benefit by a 10mm lift cam. I'd make my lift limit on the mechanical parameters in the valvetrain and piston/valve interface.

Not necessarily.... You can have less overall duration, and yet get more duration of filling. I know that sounds confusing, but (using your flow #s above) a 256 lobe of 9mm, and a 256 lobe of 8.5mm, the 9mm lobe will be @ max filling longer. The only way to get the 8.5mm lift to equal the filling would be to run more duration. BUT... running more duration changes the powerband. The point I'm trying to make is all thing being equal a 9mm lift cam will flow more than the 8.5mm cam, even though the port maxes out at the flow equal to 8.5mm

[sirdeuce]

Excessive lift is basically just wasted, the port will only flow what it will flow. So I'd say on a head that maxes flow at 8.5mm wouldn't benefit by a 10mm lift cam. I'd make my lift limit on the mechanical parameters in the valvetrain and piston/valve interface.

Not necessarily.... You can have less overall duration, and yet get more duration of filling. I know that sounds confusing, but (using your flow #s above) a 256 lobe of 9mm, and a 256 lobe of 8.5mm, the 9mm lobe will be @ max filling longer. The only way to get the 8.5mm lift to equal the filling would be to run more duration. BUT... running more duration changes the powerband. The point I'm trying to make is all thing being equal a 9mm lift cam will flow more than the 8.5mm cam, even though the port maxes out at the flow equal to 8.5mm

Ok, makes sense. I never considered a cam with excessive lift "too big". Always saved that term for the duration. That's a whole 'nother discussion though.

[CBlacksmith]

Hello Gentlemen, I'm using Chris's profile to add a little to this thread. Many test were done 1/4 century ago to determine the best cams to be run on these motors, and it was done in the US.
I am not going to get to exacting figures and numbers, but results are affected by the bench size and the inches of vacuum (water drawn). I'm not going to fuss about who said what but, I'm really too old to BS and besides you can always call an engine builder who has spent years building the 4ag for the FAT or PRO Series, I'm sure they will give you 5 mins.
Our testing years ago to really find the edge on the camshafts was to flow at 10 inches, at that rate we could see where changes in port, valve, chamber and valve lift can really change the end result general HP. Starting with an OEM casting.
On the ITA motors with non-modified heads you could gain as much as 8 -10 HP by changing the casting. We still have new TRD casting on the shelf. We found that the OEM valve job is excellent, however gains are made on a stock motor by changing the width of certain angles without altering the angle or number of angles on the seat. We also found that the maximum flow rate was well below the lift of the spec Atlantic cams and higher than your 8mm.
Dwell time at max flow lift would become impossible at the required duration to generate high HP; you would need to go higher. We tried different camshaft profiles in order to take full advantage of the flow/lift max point but many proved unsuccessful.
Let me tell that, just like a dyno take all information with a grain of salt. Our fastest camshafts have been run in the PRO series and in Group 3 FIA, in fact I always keep a set on the shelf for emergency shipments.
The old Piper Cam philosophy of low lifts and long duration was done 40 years ago. Valve-train velocity, dwell duration and proper timing are what make or break a good camshaft. I'll try and dig up some stuff for you guys and post it after I get mine own sign in name again. I'm just borrowing Chris's for this.

Thanks Richard (TED)

[sirdeuce]

That would be great! Interested in seeing some good R&D test and result reports.

[quietskaterguy]

This is a great read/debate!
thanks for your input so far Yoshimitsuspeed and oldeskewltoy