Cylinder Head Research Complete for 3800!

[ssms5411]

Re: Cylinder Head Research Complete for 3800!

I think ALM. will warp faster than cast iron, the newer L26 heads have bigger exhaust valves on them on FI engines and NA engines. Most have found 28 degrees timing is the sweet spot on our engines at WOT. I run 27 right now with my cam and have no KR and this is in 115-120 temps in the summer, so its runs pretty good. Its cold right now but I just leave my timing alone and just adjust fuel tables for the cold weather, need to richen it up.

[r_simmonds]

Re: Cylinder Head Research Complete for 3800!

Actually, Iron is more prone to warping than Aluminum. Aluminum will shed it's heat faster than Iron. It may have a higher rate of thermal expansion, but since it can cool faster it is less prone to staying at high temps that would cause warping. Most of the warping that people associate with overheating is related to Iron engine components. Aluminum is a very durable material for cylinder casings and heads. It's only recently that it's become common place for American auto manufacturers to use it more for performance engines. Seriously, there are alot of benefits to using Aluminum heads over Iron.

[Forced_Firebird]

Re: Cylinder Head Research Complete for 3800!

I am a machinist and hate to be the one to say it, but, you sir are wrong. iron heads are much more stable than aluminum, specially when over heated and/or mated to an un-like material (iron block).


Back on topic...

The red line is stock heads, yellow is what you would typically get from a DIY-job, and the purple line is what I was able to attain after several porting sessions using the flowbench...



and a printout of the graph with percent gain over stock (gained 20% avg :))...




and a few graphs overlaid (to give an idea about how many tests were done)...

[ssms5411]

Re: Cylinder Head Research Complete for 3800!

Thanks for the graphs, and clearing up the alm./iron heads warping. My Dad told me this way back when the LT1's were avaliable with ALM. heads, that for AZ heat if you get stuck on the freeway and start to over heat and can't get over in time the heads are going to warp faster than cast iron. The graphs give me a good idea on how much my DYI heads will flow. I find it amazing how much you can get from just a DYI job on stock heads. I went through mine twice to make sure I got each port pretty much the same so I'm hoping for good results. Thanks agian, must be nice to have a flow bench at hand.

[FuryCharger]

Re: Cylinder Head Research Complete for 3800!

Hey all, glad to see this sticky is still being expanded on. I must have done this research 3-4 years ago but still have my camaro in storage and goin strong! Keep it real.

[Forced_Firebird]

Re: Cylinder Head Research Complete for 3800!

Well, I have been able to see exceptional gains lately.

Boost ported heads...





That's not the latest graph, but you get the picture. Currently they flow over 204cfm at .400" and peak 224cfm at .600" with stock valves and seat angles.

[N2OEQIP]

Re: Cylinder Head Research Complete for 3800!

hmmmmm those do look good....... lol :rock:

[Forced_Firebird]

Re: Cylinder Head Research Complete for 3800!

Flow matched pretty well...

[LETZRIDE]

Re: Cylinder Head Research Complete for 3800!

I have a bit of a hard time reading and understanding this...can someone clarify for me what the stock flow numbers are on the stock set of heads please? or give me a little help reading this...? which are the intake flow numbers and which are the exhaust flow numbers?

[Pewter02Camaro]

Re: Cylinder Head Research Complete for 3800!

Flow matched pretty well...

looks to be intake port only numbers

stock flow is #1, and looks like #2-#4 are intake ports on the ported head.

And then on the right are the percentage increase numbers for each port.

Correct me if i'm wrong Forced...

[LETZRIDE]

Re: Cylinder Head Research Complete for 3800!

ok I dont understand what the percentage increases mean? how can number 2 be 139 %? it doesnt make any sense if that info is relative to number 1 which is stock?

[Pewter02Camaro]

Re: Cylinder Head Research Complete for 3800!

ok I dont understand what the percentage increases mean? how can number 2 be 139 %? it doesnt make any sense if that info is relative to number 1 which is stock?

It would be 139 percent of the original flow number at a certain lift height.

so if you look at the numbers for a lift of .1 stock flow is 60.3 the first ported runner is flowing 70.3 thats 116 percent of the stock flow number so 60.3 x 1.16 = 70.29774

Get it now? ;)

[LETZRIDE]

Re: Cylinder Head Research Complete for 3800!

wouldnt that only be 16% ^ not 116%?

[Bandit127]

Re: Cylinder Head Research Complete for 3800!

The first 100% is the whole first number. Any percentage above 100% is the percentage gain. So you can drop the 100 if it makes more sense.

Example 137%= is 37% percent more than the stock. Or atleast thats how I understand it.

[Pewter02Camaro]

Re: Cylinder Head Research Complete for 3800!

The first 100% is the whole first number. Any percentage above 100% is the percentage gain. So you can drop the 100 if it makes more sense.

Example 137%= is 37% percent more than the stock. Or atleast thats how I understand it.

Exactly