L92 heads and carb intake

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Sep 8, 2007 | 07:42 AM

#11

Flyer

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From: Armpit of East TX

And now 317's

Quote:

Originally Posted by Richard@WCCH

Here’s some results of a recent flow test of a #317 casting. The head looked to be pretty average as far as core shift goes. I tested the two center cylinders. Interesting to note how the second intake port tested flowed extremely well to .450” lift, then settled back down to it’s peak average. The test was performed on a SF600 flow bench.

Lift___Cyl1Int.____Cyl2Int.____Cyl1Exh.____Cyl2Exh .___Cyl2Exh w/out pipe
.100___64.8_______65.9_______56.6_______57.1______ ___53.3
.150___101.7______103.9______92.1_______92.1______ ___87.8
.200___142.1______141.8______113.1______116.1_____ ___111.6
.250___177.7______177.1______133.8______139.4_____ ___131.8
.300___204.3______203.4______152.1______157.8_____ ___146.8
.350___224.3______224.9______159.8______165.8_____ ___157.1
.400___233.5______242.9______171.6______175.8_____ ___164.9
.450___241.4______252.5______181.2______184.8_____ ___166.8
.500___250.0______247.0______190.6______200.4_____ ___174.2
.550___251.2______250.9______197.9______200.1_____ ___181.2
.575___253.0______251.1______199.3______202.1_____ ___183.0
.600___253.0______251.9______200.4______203.0_____ ___184.4
.625___252.2______252.2______200.9______204.1_____ ___184.8
.650___253.1______252.2______201.7______205.2_____ ___185.3

Intake runner volume = 208.5cc
Exhaust runner volume = 77.0cc
Combustion chamber volume = 72.4cc
Test bore dia. = 4.030”
The intake ports were tested with a radius flow plate and cyl. #1&2 exhaust ports were tested with a 2.0” stub pipe.

As soon as I get an intake manifold, I'll edit the post with the results.

Richard

Sep 8, 2007 | 07:46 AM

#12

Flyer

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From: Armpit of East TX

I got to thinking about it .. I don't understand how that much improvement in head flow will not yield some beneficial gains.

Sep 8, 2007 | 08:37 AM

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1slow01Z71

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From: Austin, TX

Quote:

Originally Posted by Flyer

I got to thinking about it .. I don't understand how that much improvement in head flow will not yield some beneficial gains.

I agree with you, but you cant deny the sub-par results guys on tech are getting from them for how much the heads flow they should be up another 20+rwhp. I havent been over there in a while to see what they are doing so they may have squeezed a few more ponies out of their setups by now but my only guess that the cam selection for these heads needs to be re-thought. Im not quite sure what valve events would be beneficial to such a large intake valve and average exhaust valve. It would be my guess that you could run a standard split with 8-10*s exhaust bias since the heads are lacking ALOT in the exhaust flow area when you figure out the flow ratio between the intake and exhaust numbers. Maybe people are just cramming standard cams in there and not taking into account the massive amount of air they are injecting into the cylinders and not getting it out efficiently. A cam with some nice overlap would help scavenge some of the exhaust gases out better. Im going to go over to tech and do some snooping around.

Sep 8, 2007 | 08:44 AM

#14

1slow01Z71

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From: Austin, TX

I was right

Quote:

Originally Posted by Rick@Synergy

Take a look at flow data and you will see why that cam wont be very effective. Not enough split. Intake to exhaust ratio is very different on these heads and the LS7 heads. If you wanted a big cam, I can send you one that will work.

Rick

He was speaking in reference to someones comment on a 244/248 cam.

I think that thread pretty much answers what you have to do to make some power. It looks as though with how peaky that power band is a wide lsa is a must. Did you see that he took out some of the advance for the next cam, hint, hint

Sep 8, 2007 | 08:59 AM

#15

1slow01Z71

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From: Austin, TX

Here is the updated thread for the new cam ~236/246 115
https://ls1tech.com/forums/showthrea...83#post6356783
The guy that owns the cars SN is Dame, if you look in his sig he picked up almost 250 ft-lbs of tq on a 100 shot.

My guess is the wide lsa and large exhaust bias lend well to hp/tq production on the juice

From reading all that stuff if you plan on running a 3000-3400 stall in your 80e I bet a cam just like the one in that T/A would run awesome in your truck. It may be worth-while to get Rick to spec a cam out for you.

Sep 8, 2007 | 10:27 AM

#16

Quik

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From: Pittsburgh!!!!!!!! Pa

Quote:

Originally Posted by Flyer

I got to thinking about it .. I don't understand how that much improvement in head flow will not yield some beneficial gains.

its not all about flow as SlowZ71 posted you can see some of the results. they are good heads but still unsure of what true cam specs work with combos. the 6.0/6.2s are making better numbers compared to that of the 4" strokers

Sep 8, 2007 | 11:51 AM

#17

TurboGibbs

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From: Decatur, AL

I like them but still not sold on them. The amount of power that comes in at 4500+ is pretty extreme from what there is below that. More power in the 2500-4500 range would help my straight shift on the street. I think cathedral ports would support that. Once mine gets strolling it is fun with the rpms not dropping below 5400 during shifts when you are rowing through them.
My issues with the L92's and lack of velocity at low rpms is just something that would really be a problem with a manual tranny, and a heavy vehicle. An auto with a good stall would never even notice the loss in low end IMO.