RED-85-Z51

Curious, im going to 64cc aluminum brodix heads, what was the volume of my old stock L98 heads?

I dont want to head backwards on compression...

Also, was was the "cc" of the stock pistons? negative or positive?

powerpigz-51

your stock chambers are 76cc. Stock compression is 9.0 to 1. That puts your stock forged flat tops about even cc, maybe 1-2 cc negative. 64cc heads put you at 10.3 to 1, which should be fine with the aluminum heads. My motor has Speed pro forged with +6.5 cc, I am going to run 70cc Edelbrock E-streets. I am currently running stock 85 irons with a .029 head gasket. I have to run premium with the speed pros in there.

CFI-EFI

The stock 1985 Iron heads are 76 cc combustion chambers, as stated. The forged pistons have a valve clearance trough, instead of two or four notches or eye brows. The trough displaces 3.4 cc. The stock gasket is .021" thick, compressed.

RACE ON!!!

RED-85-Z51

So if I go with 64cc heads, and +5.40cc Wiseco PT003HS pistons, stock gasket, 0.015" deck height, I should have around 10.5:1 compression....

That should make for a good street/strip engine...not too wild, but much much better than 9:1

RED-85-Z51

The stock pistons out of my engine had a trough instead of the reliefs, but those are cast aluminum right?

JAKE

Just for info: Tests show that a 1 pt change in CR results in a 3-4 percent power difference. Power change isn't linear though. The difference between 10.1:1 and 11.1:1 is at 3 percent but 8.1:1 to 9.1:1 is at 4 percent.

These are just averages from the tests one mag made. Just ballpark stuff.

Of course, tuning will be needed for an iron headed 10.5 CR engine since iron doesn't dissipate heat as quickly so has less CR tolerance.

Considering only the material they're cast from, iron heads hold heat better and generally make slightly more power than comparable aluminum jobs, yet are heavier, more difficult to repair and less tolerant of high CR. AFR clued me in on that many, many years ago, long before Hector was a Pup. LOL

One of the touted benefits of LT1's revised cooling system was to enable higher CR without problems.

Jake

West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!

JackDidley

Your 85 came with forged pistons. Good parts but if you have to bore it cast replacements will be OK.

RED-85-Z51

Here is what im doing.

Stock bore and stroke.
Bump compression to 10.5:1 with 64cc Brodix heads and tighter Forged mahle pistons.
The heads have slightly larger valves than stock, and have larger 180cc runners than stock.

Do away with the stock manifolds and install TPiS longtubes and TPiS front Y into a test pipe and out a Borla rear Y into Magnaflow mufflers.

Delete AIR system, and EGR valve.

High volume water pump, 180* T-stat.

24 lb/hr Bosch3 injectors, adjustable FPR for fine tuning.

SLP runners, stock plenum and (for now) stock intake base.

Lunati VooDoo 60101 Hydraulic flat tappet cam/lifters.

underdrive pulley kit

Hypertech D.U.I. distributor

new single non-roller timing set with metal gears.

Forged rods, stock crank, all new bearings and seals.

1.6 Lunati VooDoo Roller Rockers

Melling oil pump (standard volume) with Higher pressure spring.

And a custom burned chip/tune...

fwiw, im putting a Greenwood functional wing, Stage 1 front spoiler, lowering 1.5 front and rear, and putting on black ZR1 wheels, 9.5 front and 11" rears..

Honestly, Im hoping, after it all, to have a reliably running car that if for some reason my other 2 vehicles wont crank, I can drive the car to work if needed, 40 miles round trip..

But also take the car to the strip if I want to and Lay down some 1/4 mile passes..

Id be absolutely thrilled to have numbers in the 300hp/375ft/lbs range...on 93 octane. and get 24mpg on the highway, and maybe run under the 13s mark...but I think that's just pure optimism on my part.

RED-85-Z51

nice, I looked down inside one of my pistons and I can clearly see the TRW stamping...

Part number 464664


No signs of wear...awesome!

powerpigz-51

You need to decide on which pistons you are going to use before choosing your head cc. The 64cc chambers will be ok with the stock pistons, but will be at least 11 to 1 with the Wisecos. I am not sure I would go that high. That cam is a great choice, but you might consider the 102, that is the one I am going to run. My understanding is that these are fast ramp cams, and with the 1.6 rockers, I would be concerned with valvetrain issues. Maybe not so much with the 101, but I plan on running 1.5's with my 102 Voodoo. I am also going to mega port some SLP's and raise that rev wall a bit. You and I are in the same boat, building a flat tappet 85. I am still in the planning stages, also and am not married to anything yet as I am still collecting parts. I don't think 300 horse to the wheels is possible with our flat tappets. 350 at the crank maybe with a really good tune.

JackDidley

You will not see 12.s with that intake unless you use a high stall converter and sticky tires. Unless you race a lot dont sweat it. You cant tell the difference between low 13.s, and high 12.s on the street.

RED-85-Z51

Ive already got the 60101 cam, so Im kinda married to it, and IVe been told by more than one tuner that it is about as wild of a cam as you can run and have a solid reliable idle.

I had one tuner tell me he couldnt make a chip that would make a VooDoo cam idle right and would only touch it if I brought the car to him for a dyno tune.

I gave him the specs off the cam card and he was shocked, he didnt know that there wa such a voodoo cam, and that he could make a chip that I ould be very very happy with...

Here are the specs off the cam card.

Valve lift .454int and .468ex
Lobe lift .303int and .312ex

Adv. duration 256int 262ex
Duration # .050" 213int 219ex
Centerline 108int 116 ex

Timing @ 0.050" tappet lift
BTDC -2
ABDC 35
BBDC 46
ATDC -7

RED-85-Z51

Yeah I dont plan to keep the stock intake base for a very long time, Ill replace it with most likely an edelbrock unit, or an SLP Bigmouth unit, depending on what I find for the money.

Also, after the engine is done and installed, and the exterior goodies are put on, and I get it ready for paint...Im going to pull th D36 and put on an adapter plate for m 36 batwing, and install a new D44 center section with probably 3.54s

That should put me solidly in the mid 12's Id think.

powerpigz-51

Based on what your tuner guy said, maybe the 101 Voodoo with the 1.6 rockers is the way to go. Who is doing your chip?