Thanks in advance for all your help. this site is super informative.

Okay originaly i had a 02 lq4 going in a 67 camaro. I bought a mild cam with these specs
Intake Duration: 225 @.050"
Exhaust Duration: 229 @.050"
Intake Lift: .580"
Exhaust Lift: .590"
LSA: 114+4
I never installed it and traded the motor and got a stock ly6 instead.
I was told this cam would not work well with an ly6 motor as it is designed for a gen III.
Would this motor work well for a stock ly6 motor of course removing the vvt.

thanks for your help
bpatrol

 

Its a good catherdral head, non-vvt motor cam profile.

 

my heads are L92 i believe square port casting similar to a ls3 head I believe. will it still be ok?
thanks bpatrol

 

I would not run that cam with those heads..

L92/ls3 style heads are very picky because of the over sized valves. Therefore they also don't need a large cam to make killer power.

They like larger splits (6-9* in most cases) something like 220/228.

It would work but I would go with something more suited for that. TSP sells some nice l92/ls3 cams that are off the shelf.

And you are correct on your heads.. Only difference with them and ls3 is the stems.

 

No. You would want to use a cam profile with alot more exhaust duration then. Example: 227/241

 

...^ x2

 

thanks I guess will sell the cam

 

I've got a 229/236 in my lq4 l92 headed engine...

 

Good choice. What's your engine combo? Maybe some of us can help you spec the correct profile out for it?

 

OK, the advice is all over the place, but here's the real skinny on those L92 heads: They don't need as big of a split as many of you are saying. I've said this on many threads and I'll say it again, the L92/LS3 heads flow slightly better than an LS2 head on the exhaust and much better on the intake. So if they flow a little bit better on the exhaust, why in the world would you recommend such a large duration on them, but not on a cathedral port head? For example, a 228/228 (228R) cam is very popular with the 5.7/6.0 cathedral port heads. In this case, 228 is plenty of exhaust duration. So now, you add an L92/LS3 head with the same or better exhaust flow and now you need duration in the upper 230s or low 240s? That makes absolutely no sense at all.

Yes, the rectangular port heads flow very well on the intake side. It's been well documented that they require 4-6 degrees less duration than a cathedral port LS2 head to make the same power or more. So if a 228R would be a good daily driver cam for a 6.0L, than a 224/228 or a 222/228 cam would be appropriately sized for a 6.0L with L92/LS3 heads. Those who are advocating huge exhaust duration are not looking hard enough at what's going on in the exhaust cycle of the combustion process.

Bottom line: The 225/229 114+4 cam is perfectly fine to run in the LY6. While it may not be ideal, it's going to be close enough. I'd run it for sure.

 

The cam is most likely a 3 bolt design. It can work in your LY6 just fine. You will just need to get a timing chain for a 4x cam sensor and a three bolt timing sprocket to match your cam. I know Comp makes them.
This is exactly what was going through my head as I was reading through this post, except for I would want to keep VVT. But thats an entirely different conversation!

 

The exhaust ports suck on both of these heads Pat. Even your friend Geoff @EPS uses more exhaust duration on the LS3/7/92 stuff. But I do understand your point/theory though. It's all in the particular engine combination and what parts are going to be used with what and how.

 

I will see if I can find some flow numbers for the L92 heads. Richard at WCCH did some early flow testing and blueprinting of them when they first came out. If you compare the L92 exhaust flow to any 243 (LS6/LS2) exhaust port flow, you will see that they are the same or slightly better. I don't ever hear people say that 243s have sucky exhaust flow so if the L92/LS3 exhaust flow is the same or better, how can they be considered sucky? Just asking a legitimate question.

 

Stock L92 head flow numbers from Richard at West Coast Cylinder heads:
4.030” test bore
Lift ___.100 _.150_.200_.250_.300 _.350 _.400 _.450 _.500 _.550 _.600 _.650_.700_.750
#1 Int. 74.9 109.4 154.4 193.5 225.3 252.8 274.6 292.7 308.8 321.0 328.7 326.6 310.0 316.6
#1 Exh. 63.6 97.9 126.1 148.7 162.3 178.6 189.6 197.6 205.5 210.7 214.6 217.8 221.2 223.5
The intake was tested with a radius plate and the exhaust was tested with a 2 ½” stub pipe.

4.155” test bore
Lift ___.100 _.150_.200_.250_.300 _.350 _.400 _.450 _.500 _.550 _.600 _.650_.700_.750
#1 Int. 73.8 108.7 153.2 192.6 225.2 253.6 277.0 296.7 313.0 326.0 335.8 326.9 327.3 317.1
#1 Exh.61.1 97.9 125.7 148.1 162.0 179.5 191.8 200.1 205.9 213.3 218.4 220.9 221.9 223.2
The intake was tested with a radius plate and the exhaust was tested with a 2 ½” stub pipe.

Casting Number 243
Head: 2001 LS6 5.7 Liter Passenger Car
Material: Aluminimum
Part Number:
12564243
Combustion Chamber Volume: 64.45cc
Compression Ratio: 10.5:1
Intake Port Volume: 210cc
Exhaust Port Volume: 75cc
Intake Valve Diameter: 2.00 inches
Exhaust Valve Diameter: 1.55 inches

Stock 243 (LS6/LS2) Head Flow Numbers
Chamber 64.45 cc-------0.100---0.200--0.300--0.400---0.500---0.550---0.600
Intake 210 cc------------62------126----184----224-----251----256----257
Exhaust 75 cc------------57------108----143----163-----176----180----183

LS2 head flow on Bo White's flow bench:
.200 137/115
.300 194/150
.400 237/175
.500 262/186
.600 251/197
3.900 bore, 1 7/8 pipe

I'll try to find some more flow numbers. Anyway, the point is, the L92/LS3 heads have a larger 1.59 exhaust valve and larger port and flow more than LS6/LS2 exhaust ports with stock 1.55 exhaust valves in these flow sheets. My point is, it does not make sense to give a 6.0L more exhaust duration with a L92/LS3 head than you would with an LS6/LS2 head. I hope these flow sheets help support this. It's the intake that can take LESS duration.

 

I should have said more like poor instead of sucked I guess. But just comparing some of the data and looking at the E/I ratios between the 2 is what I ment.(depending on lift points you use as comparison) That's where the aftermarket stuff really improves on. And you do have some correct points in your statements. It just depends who you talk to and what there thought/theory is on the LARGE/small split stuff. I agree totally on the LESS intake duration.

 

My opinion on this is just that not a fact but will help clear some things up about L92 heads. They are a smaller version of the LS7 head, A port mould of a LS7 head is very similiar to the Ford D3 cylinder head, they use the C3 version in Australian V8 supercar. So basically the L92 head is derived from a competition engine, its no different then a 15 degree small block chevy, so it should be cammed like one for performance. For one I do not see any big splits with any of these heads generally no more then 6 degrees and mostly on 2 to 4 degrees with a substantial amount of overlap. In saying this the L92 is a production cylinder head and it has a large intake valve and this creates a large curtain area at low lift as well as a big port means low lift cfm numbers are quiet high coupled with a large curtain area means they are very sensitive to larger cams. This is because the valve area is unshrouded and high amounts of reversion take place. This is why the VE is sometimes all over the place or you see some engines have issues with fuel curves with carbs from the combination of overscavenging and reversion. This is why low rpm bucking is so much more apparant with L92/LS3 then it is with the older heads with only a moderate amount of overlap. So to sum it up your cam is fine, you don't want a lot of overlap with so much low lift flow otherwise it wont start working until right up top then your valvetrain cant handle it anyway. The more duration you use you should also spread the lobe centres. Small splits keeps overlap down which helps. I think there is not much need to go over 8-10 deg overlap, As it will still be a very effective amount and most likely the same effectiveness as 20 degrees plus in a LS1.

So for a budget cam swap stick to smaller splits on wider lsa numbers with a good spring set up as the intake valve is heavy.

There is a lot of documentation to suggest a big exhaust split ie 10 deg plus will help the engine hold onto peak power for longer after pk torque, which is good for a drag race engine. A small split is the right balance and helps build mid range and top end and improve avg numbers and also works better with a hydraulic valve train as they are rpm limited.

So people wonder why don't we use tighter lsa's like the D3 Ford heads. Well the L92 can be improved upon. If you look at the MAST versions the valves are shrouded to reduce low lift numbers which reduces overscavenging with large overlap cams. Don't confuse this from shrouding from intake to close to the bore this isn't as big issue as people think. Shrouding around the valve at low lift is important, as is 50 deg valve seats, this also cuts low lift flow.

Just buy removing the lump in the intake port improving the short turn and around the valve guide boss on the intake and opening the ex up to 88-90% of the valve size is all thats needed. Don't take anything out the choke its already on the large side. Then do a good valve job this will pick up top end cfm numbers and introduction of 50 deg seats on intake and ex will cut low lift flow right back. This will reduce overscavenging and reversion and improve hp. Then more traditional small block chevy cams can be implented for the search of more horsepower. I think most aftermarket CNC L92s have to much out the choke just improve a few things and it picks them right up.

Also another trick is to use an intake manifold with a 3 degree taper from bottom of the runner. The manifold exit should be smaller then the cylinder head this will move the choke of the runner to the manifold. The smallest cross section of the cyl head is an inch before the short turn, this determines where peak power is optimum and after this rpm the air goes turbulent. The L92 is a little to big for the 6L. The manifold can be made smaller so the choke is smaller and better for a 6L. While it is not text book practice it does work very well and is common with older 4V Ford heads which are to big and have a terrible short turn the 2V manifold made them a lot stronger.

 

thanks for saving me! i was bummed everybody thought my cam would be a poor choice. Im not building a uber drag racer. just a 67 camaro with some cruising power. basicaly a ly6 with vvt removed and a cam and headers with a tune.
bpatrol
I know everybody tries to help and has opinions, its hard to pick from them sometimes

 

Great post hym, very informative from an engineering standpoint...do you port heads for a living? Your post really helped me understand the design of a cylinder head....this will help as I hope to use an LS cylinder head as a project in my computational fluid dynamics class in the upcoming semester...good looks