DavidBoren

I was concerned with the quicker rate of acceleration near top dead center brought on by the longer stroke. This is why I am so obsessed with port velocity. And why I made such a big deal about more air getting past smaller valves.

With less dwell, and a faster rate of piston acceleration away from TDC, I figured that the increased intake velocity is a necessity.

Obviously, the smaller intake runner of the 205 heads will be far superior in this regard, compared to the stage two ported truck castings.

It's also why I think that a long intake runner in the manifold is necessary, and thusly I want to use the fast rt 102/102. I think it will better promote cylinder filling in the first couple degrees of rotation, as the piston is accelerating away from TDC at its fastest rate.

The pull of the pistons should be highest at this point, as well, and having a long intake runner, with a lot of air "stacked up" seems like it would capitalize on this event the best.

I could be absolutely wrong with all of that, but that has been a guiding logic/principle of this entire undersquare design, for me.

I haven't considered the kick versus the leg press, and I will have to look into that. Thank you for bringing it up.

NAVYBLUE210

David
I like the idea by ARShale with the 3.90" stroke & the 6.25" rod.
for a naturally aspirated combo. The longer rod/ratio will have less
Friction and load on the major thrust side of the bore.
As you know the heads will make or brake your/any combo and the
Decision to wait/use the MMS 205s (which should be ready pretty soon)
will determine the results and success of your goal. Having the throat
and cross section matched to valve size and the bore size will give you
The air speed and velocity you are looking for. The next part in my
Opinion is to have the FAST RSXRT truck intake you have already
mentioned MAMOFIED as this will provide another 8-15 HP & lb ft
Throughout your power band (2500-6500RPM) not just at peak,
In addition to the 12-15 the truck already provides over the
FAST 102 for Cars.
If you really want to go crazy (why not it's what we do LOL) look into
Some Burns custom stepped long tubes specced to your HCI something
Like 1 5/8-1 3/4-1 7/8. But seriously 1 3/4" as long as will fit your chassis
Will work excellent.
With regards to the under square design philosophy if you look at all
The ENGINE MASTERS Results from the beginning (I have). The street
Engine set-ups, hydraulic roller cam, 11.5:1 max compression, and
2500-6500 operating range the under squares perform better!
I believe you can reach 580-600 FWHP (480 ish RWHP with your
automatic/drivetrain) with 3.73:1s and TRACTION sub 3200lbs could
run 10s and be extremely street able with a 223*-227* intake duration
Probably symmetrical pattern with a narrowish (112* LSA or less) +3*
obviously specced by Tony and or Kip.

Turbo I would go 4.8 Crank, Long Rod with 12-15lbs of twin turbo boost
@ 10.0:1 Comp for ~800 FWHP.

By the way I appreciated and benefitted from your thoughts on vent
Placement on the hood for heat extraction and downforce, as I have been
Considering this for my C5 Top Speed Project for some time!

DavidBoren

Thank you for the response. I have been wondering about headers, so thank you again for the recommendation. I will look into Burns, for sure. As well as poke around the engine masters builds. That specified 2500-6500 rpm range is exactly what I'm looking for. I'm glad I could help with the hood vent placement.

I would love to build a turbo 4.8 with the longest forged rod I could fit. I think it would work awesome in a awd chassis.

DavidBoren

By the way, I was already planning on using stepped headers. I was thinking 1.625" to 1.75" would be good for the low end torque I'm after.

But I never thought about triple stepped headers. I like the way you think, sir. Thanks again.

96capricemgr

iTrader: (1)

Since we are focusing solely on benchracing and theory..........
I would think you want the bulk of the power transferred to the crank quickly with as little surface area compared to volume as possible because any heat that makes it's way to the cooling system is wasted.

V8Hopeful

So I hate to be a newb and dredge up a old thread but did this ever get built? I currently have a 6.0 2500 4x4 6000lb truck with 4.10 gears and 33" tires and a spare 4.8 iron block motor. My truck has little over 200k on it and wanting to build a spare motor to stab in when time comes. I have thought of either junkyard 6.0 or 5.3 but since I already have the 4.8 and the block is shared with 5.3's I have thought of using it as the foundation for the build. Looking to get input on the build idea below.

Plan is
4.8 block (less than 100k on it)
4.00 stroke callies crank
stock pocket ported 799 heads
new stock 6.0 cam
LS6 springs
1.8 Summit rocker arms
Wiseco pistons for 3.78 bore 4.00 stroke and 6.125 rod
cheapest 6.125 rods I can find
stock intake
stock 5.3 or 6.0 injectors (need to see what size they each are and maybe dyno it with both sets)
small tube headers with 3"single exhaust

I use the truck to pull trailers frequently and was thinking the smaller bore large stroke would be a better low rpm motor and might bump MPG's up by simply being in the power band during low throttle cruising speeds along with the small bore having better combustion pattern and more complete burn.

Tuskyz28

David, thunder racing did a 359ci years ago in a red 98- 02 camaro..car had silver flames. I'm sure Geoff at EPS cams or Pat G can give more information about that car/combo.