DavidBoren

My more complete line of thinking on this subject is that LS7 heads will require a new intake, and so would cathedral port heads.

Big intake runners are meant for higher flow at higher rpms, yet suffer a small but noticeable penalty in torque produced at lower rpms. With a stroke longer than 4", you are starting to approach some pretty serious piston speeds, so your redline should be kept in check.

If you are going to be restricting the redline, then I think you should focus on heads that generally perform better in the lower rpms. A good cathedral port is still going to flow excellent at high rpms, so the cathedral port in no way inhibits your build. In fact, it caters to your borderline excessive stroke by providing the much needed intake air velocity to match your borderline excessive piston velocity.

Call Tony Mamo, ask him what he has to say on the subject. I'm no expert, but he is.

hrlyhnx

iTrader: (3)

Tony IS an expert but more so with Cathedral over square port. No disrespect to Tony but if you're 80 years old, 100lbs overweight and feeling chest pains, you're not going to the best oral surgeon in your area....are you?

Tony may not be the BEST person for advice on this Cathedral vs Square debate

Be careful and do your research!

NAVYBLUE210

Tony was porting BBC & SBC Heads years before there were LS Engines,
Or even cathedral heads.
Not that he needs my defense but you might want to use a different
Analogy LOL!

NAVYBLUE210

OP, New Fast medium length runners + 50-100 more N2O is you're easiest,
Most inexpensive route to your goal IMO, Iron Block correct?
What is your RPM HP Peak currently?

Jimbo1367

IIRC, the GM engineers clearance the block to fit the 4.065 bore similar to the old 409s

breze84

I have Carl Wegner L92 279cc heads on my Forged LS7 427ci making over 510whp on a mustang dyno with a RPM Stage 6 4l65/70 auto swap / 3200 converter on a 27.5 19" DR...

Zfan

Wow, forgot I had started this post. My 4L80E transmission took a dump so I have had the car apart for a while. The block is a LSX iron block with 4" stroke Callies magnum crank and Callies ultra lite rods, Diamond flat top pistons, bore is 4.165.
Still trying to pull the trigger on a set of heads and mate it to a MSD intake manifold.

Zfan

Forgot to mention my friend just had Tony Mamo build him a set of Trick flow LS7 heads with a Mamo ported MSD intake for his ERL built 431. He's going with a tight lash solid roller for the street.

Che70velle

iTrader: (6)

I spoke to Tony 10 days ago. His LS7 program is making some outstanding numbers. The head casting that he utilizes, provides enough volume to flow over 400, yet is efficient enough to still allow a very fast moving air charge at low rpm, making his current setup literally the best of both worlds.
If you have the coin, and your looking to make big power, WITHOUT sacrificing drivability ,Tony's LS7 package is hard to beat.

Faisalowski

I have a lq9 427 ci with 4.070 bore and stroke 4.100 with 11.5 cr

My camshaft TSP Ls7R cam spec:

With 1.8 rocker arm
248/256 655/655 114 Lsa

With 1.7 rocker arm
248/256 618/618 114 Lsa

And i confused what heads to use Ls3 or Ls7

Now i have LME GM Ls7 cnc ported heads from my old setup. Can I installe them with out any problems in valves

Heads specs:
http://www.latemodelengines.com/inde...ads-group.html

Thanks in advance

ramairws6

iTrader: (33)

Dats some funny chit right there! ^^^ Def. will not "blow" a Fast 102 ported outta the water

NAVYBLUE210

Actually starting with 427", "well ported stock heads, and a HR peaking
~7000 RPM & shifting ~7500 RPM MAMOFIED MSD 12-15 better than
MAMOFIED FAST 102. 434"+, MMS LS7 Heads, LLSR specced for
7000 RPM+ HP Peak, shifting 7500 RPM+ Probably 22-25 RWHP +
Better! Depends on Build & Goals.

slogo

Something to read, https://ls1tech.com/forums/generatio...re-engine.html

NAVYBLUE210

I would use MMS LS3 Heads on a 4.070" Bore,
enough airflow for ~800 FWHP.
They worked really well in my build. Your cam should work
very well also, what is the advance. Use the LS7 Heads
for a 4.125" bore or larger build , or sell.
My .02

Zfan

LSX block, 4.165 bore with 4" stroke
488 rwhp at 6700 rpm's
WAS STILL MAKING POWER AT 6700 but not enough to keep spinning it with the torque drop off.

Zfan

The stock casting heads 5364 GM LS3 heads are actually a stage 3 design with 2.20 intake valves and 1.61 exhaust valves. Never had them flowed but am curious how this really works coupled with the 4.165 bore?
I was entertaining a Trick Flow LS7 head but am a little worried as I have heard and seen some bad failures with the Trick Flow LS7 heads, mainly with boosted applications though.

NAVYBLUE210

The shorter (Mid Length) Fast runners should extend you're
Peak HP at least 400-500 Rpm and be worth 20-25 RWHP
and carry 400-500 beyond that if you have valve train control
and stability. LLSR is also an option. I would have the Heads
flowed, they should be enough for 700+ FWHP.
I hope to have Dyno #s with MAMOFIED LSX LS3 with Mid Length
Runners on my Engine 23 Feb.

Dark Energy

Navy you said it.

Put a nice solid roller or add more lift(To Take advantage of the port program) and be done get over 500 to the Rear and if you get it to hook easy sub 6.0. If I'm not mistaken I'm the one who recommended you to Chris. Didn't we talk way back over a phone call. I maybe mistaken.
1st: Add Compression * cheap mill* if your not there already under 12.0 more like 11.8 and ADD more lift the hole or Runner is larger than stage one heads. The Airflow and Air speed are IMO being Killed by a low lift cam this is Not a smaller runner head nor is it a Large one in comparison to some aftermarket Ls3 heads out there that we know make HP. You've got about a 2.6 to 2.55″ for cross section on a stage 1 with 267cc runners so with that your Larger. These little simple things should help while not having to purchase a New top end $5k plus. Solid roller or a Cam with better lift and a Fast intake with some decent Compression. Done. Call Kip, Pat G.,Martin Smallwood, Mike Jones or anyone who who does a Decent cam and I'll Bet they'll say guy's on Point. Take advantage of the heads. That style intake just kills past 6800 to 7k + but Everywhere else your Killer.

A lot of peeps talk about air flow and air speed. I'm around 2.4 in cross section with Air speeds reaching over 400 just past the valve with under 255 cc and this was on a test bore of 4.060 flowed .379 @.700 Looking to get mid 390 once all is said and done and still be under 260 cc. Just food for thought.

Dark Energy

http://www.yellowbullet.com/forum/sh....php?t=1204610

Have Kip or some one do a smaller version with less lift. Fast intake would kill around 30-40 hp but TQ would be off the chain.

Check this guy out, old basic factory intake in comparison to a High ram,single plane would be around the same to give you a idea. It's not the same build but HP/TQ numbers in reference to intakes and Rpm. Lets say if you were to just copy the cam specs from the build above. Just a reference.

https://ls1tech.com/forums/generatio...s-700hp-n.html