A.R. Shale Targa

iTrader: (2)

There was a time back in 93 when the General was having to test and design with cast iron cylinder blocks because the early aluminum casings were literally exploding apart. They eventually learned that the main block webbing needed to be able to breath (vent) to the adjacent pair of cylinders.
Same number of cubic inches below the pistons as on top of them.....
your plan of pulling vac. dramatically improves ring seal which translates to added power....less ring flutter equals more pop sealed on the top side !!

KiwiKid

Hi Tony,

Very interesting account, but one I am sure the General would not admit to. The theory is well understood and one I alluded to in my previous post, but its easy to understand how thing's evolve over time and and the fact is that oversight's happen all the time.
There is also no question least in my mind, that maintaining a relatively high vacuum in the crankcase also assist's in that venting requirement, however, in the absence of knowing exactly what we were dealing with we worked on the bigger is better principle, or KISS principle [Keep It Simple Stupid]

Violence.z06

iTrader: (3)

Why go this route vs running a Dart ls next block? Class rules?

Tuskyz28

Is you go run a LS7 head ?

KiwiKid

Bore size [max 4.165] and a dislike of the spacer rail kit to extend the pan rail down to were it needs to be for our application.

KiwiKid

I is going to run a custom ported Ls7 Cylinder head Tusky, not quite sure whose at this stage, but I am leaning toward's starting with un-ported Edelbrock Ls7 Cylinder head's.

I will keep you all posted as more bits of the jig-saw puzzle fall into place.

lil john

What happened 2 the Lsx CT heads:-)

KiwiKid

Hi John,

Change of plan basically, it would have meant a change of Headers and locking ourselves into an orphan inlet manifold.

I am now focusing more on a 3,000 RPM minimum power band, which means we will have to sacrifice a little top end, with a smaller runner than I though we could get away with, and we may not quite make 800BHP at 8,200 RPM.

However, more than one cylinder head CNC porter has said that they can achieve 400CFM with a 265cc runner and 2.200" intake valve in an Ls7 aftermarket head such as Edelbrock bare un-machined casting. So just really trying to figure out which way to jump, because the cylinder head is really the heart of the engine, which is why I guess you love them so much, and pretty much everything else revolves around the capability of the cylinder head to achieve the desired end result.

Cheers,

Mark.

lil john

I truly understand, one of the reasons I'm trying to learn to be content. I've priced actually every head made for the Lsx platform (as i really like heads) for my 408 and I came to the conclusion that even with the fact of me switching heads from my Ls3 ported heads all add up to well over 5 grand with running a solid roller with anything other than a Ls3 based head and that I can still run adjustable stud mounted rockers for cheap.
RHS small port bare heads with port work from FRH's will come out to be around $2400 throw in shaft mounted rockers $1300 still with no parts springs,valves ...etc.
The Lsx CT heads bare are around $2400 throw in a custom port(for a 408) from my guy Chris again @ FRH add $2000 we haven't even talked about rockers,valves,springs...etc.
My better idea was to call Martin @ Tick and ask if we can do a bigger cam @ only $499-599 a pop and just move the RPM up from 7400 to closer to 8000 grand. I'll be buying it this summer, I got a few other problems like my truck running hot.
But I like the thought of 800 that's what I'm now after. Cam change sounds better than a top-end swap:-)

lil john

Here's one from another post I did.

Small bore program is 269.5cc, 2.155 intake valve and 1.600 ex. Flowed on a 4.070 bore. Remember that the RHS heads have a longer intake port to compensate for it being raised on the flange. Meaning that a 269.5cc RHS port is close to the same as a 255-260cc port in a stock head.

FRH 269.5cc port with a 2.155 intake valve and a 1.600 exhaust valve, flowed on a 4.070

Intake flow
.200/163
.300/239
.400/295
.500/341
.600/377
.650/383
.700/392

Exhaust flow without a pipe.
.200/117
.300/160
.400/208
.500/229
.600/243
.700/245


Your bore is bigger:-) BTW throw in that 2.20 intake valve and you got your # Easy.

KiwiKid

Thank's John,

Excuse my ignorance what would you expect the flow numbers to be tested with a bigger cylinder bore ie. 4.185"

Also on the RHS heads, do the raised inlet ports still line up with an Ls7 inlet manifold or does it require a custom manifold?

lil john

Yep everything lines out the same, if your were to go to a bigger bore and valve I would expect around a 10 to 25 cfm jump. I'll look @ my files to see what the difference was from 4.030 to 4.125 with no change in valves just bore size.

lil john

Luckily I got my paper files more organized than my computer files for each type of head.

Web page http://www.proheads.com/WCCH%20L-92.html

Nothing exact but rather a general Idea:-)

Violence.z06

iTrader: (3)

I was thinking the same on the valve sizing. I will be running the same bore on my 350 inch build with a 3.185 stroke and im shooting for a 2.250 intake valve and more rpm.

Tuskyz28

Who go spec the cam for your build Kiwi?
The way heads really interest my boy lil John I'm like that also but about the total combination. I love looking at every component. I agree with you guys that big 4.185 bore go love the big *** valve. I personally think some of these valves especially with rectangular builds can be too big with a smaller bore but that's not the case here...... :-)

KiwiKid

OK Tusky, I think I get your drift! When we know the actual flow numbers on our chosen cylinder head's we will consult people like Martin at Trick, and maybe 1 or two other's, just to see if their is some sort of consensus amongst the expert's out there, so it will be at least a couple of weeks before we know those numbers, and again I will post that info when it comes to hand.

KiwiKid

Hi LJ,

You will be pleased to know that after several months of investigating the best Ls7 style cylinder heads for our road race application, I settled on West Coast Cylinder Head's to supply me the complete cylinder head package.

Richard certainly is a pleasure to deal with and coincidentally he is just finishing a very similar engine build to mine for a naturally aspirated Time Attack car. Richard is also speccing and supplying the cam as well as providing me with the Exhaust spec's so we can fabricate headers to best suit the engine build.

His all up price was also far better than I could have purchased all the different componentary for as obviously he buy's Titanium valves and the Jessel gear at much better prices that I could, and his mark up's must also be very low. I priced the Victory Titanuim valves myself because I believe they are the best valves money can buy, however, Richard must get a hell deal on these because they are considerable less than buying them from any body else

The list below has changed as I have up spec'd the valve spring's to the Pac's as they have an excellent spring package for .800" lift at the valve, using a 1.8 rocker ratio.

Camshaft details to follow in my next post, but the lobe centre's Richard want's is 106º, depending on the availability of the Cam billet, but we may have to go to 107º if the billet he want's is not available.

Cheer's,

Mark.

All Pro LSW-1 12o Cylinder Head's machined for valve cover rail O-ring seal.

All Pro copper alloy seat, Victory Titanium Intake Valve. All Pro 2.20" X 5/16" stem X 5.450" long w/beadlock groove. CRN coated. Victory Titanium Exhaust Valve. All Pro 1.60" X 5/16" stem X 5.450" long w/beadlock groove. 45o valve seat angle.

Manley 1.570" dual valve spring kit. 260lbs@2.00" 660lbs@1.250" 23643 titanium retainer 42343 spring seat Manley 13121-8 10 deg Lock .3110" Beadlock. +.050" height. Note: The spring and spec's have been changed details to follow.

Jesel rocker arm kit for All Pro LSW-1. For 1.965" guide spacing. Jesel rocker arm bolt 5/16-18 x 1.250" Viton Valve seals. 8mm X .490"

All Pro Valve Cover's. Includes mounting hardware kit.

CNC Custom Porting 285-108-69 for All Pro LSW Heads Competition Valve Job V8 Cylinder Heads Install and Hone Guides to size.

SurfaceCylinder Heads Wash and finsh assemble.

lil john

There the best Ls7 castings...Great to hear that you got what you where looking for.

KiwiKid

Glad to hear you think so, as I said its been a long journey to find the right cylinder head's for our road racing application, which requires a very broad power band all the way from 5,000 RPM to 8,2000, and still deliver approximately 800 BHP, and close to 600 Ftlb's of torque.

In the next couple of weeks I should have some cool pictures of some of the internal's such as the Billet crank and connecting rod's etc.

Cheer's

Mark.

lil john

Yeah I looked over all the Ls7 castings that Chris has done @ FHR it's very clear cut that they are the best castings he gets the raw port and does his own custom port. Here you go:

Yes this starts as a raw 12-1 with pro ports, no chambers, or guides. 318cfm@.400, very strong mid lift numbers.
This is yet another one of our very popular LSX based heads is our BANSHEE. This head is our best offering for the LS7 platform. This head is not only a great quality casting but has some very impressive flow quality and port trajectory since we moved the pushrod. We have 4 different programs for this from 410 outlaw to big inch power adder. this particular port program is our 29Xcc port that flows 437int and 285cfm ex.