spina74

iTrader: (12)

I have a 6.0 bottom end with forged flat top pistons, forged 6.125 rods, headers, 243 heads, ls6 intake with a 80mm tb, 42lb injectors, and and MS4. My car dynoed 410rwhp, and 399rwtq. A friend of mine has has the exact same parts on his stock bottom end LS1 only he has 241's not 243's. He too made 410hp, and a little less torque...kinda a kick to the nuts. My machinist said an MS4 is too big for 243's. I was thinking of recamming my car because I honestly feel I should be higher than only 410. What cam would be good for the stock 243's and even better for ported ones. My goal is 500+ with the ported heads and a fast 102 when I get it. I'm looking for more power, slightly better driveability, and can the LS motors be recammed without pulling the heads?

Tainted

iTrader: (9)

Does seem low but you aren't going to hit 500whp on stock cubes without nitrous or boost. The bigger the cam you go the worse your driveability is going to be and the ms4 is an already big cam

DietCoke

iTrader: (18)

500 is a drop in the bucket for a well matched combo, especially on a 6 liter. You can do it with an ls1 even, without anything too fancy.

Apply heads, apply intake, apply compression, spin it high enough, and you'll make the number.

lemons12

iTrader: (71)

Yes you can.


Op.. get a nice set of heads. Get your compression up. Get a better Intake.

With a nice set of heads, fast intake, you should easily hit 480.

Also, a 6.0 wont make much more than an ls1.

You can keep the heads on for a cam swap.

You can hit 500rwhp with a nice set of 225s/nice intake and mid 22x/22x .600+lift cam.

Tainted

iTrader: (9)

Yall must have missed the part about him wanting to use stock heads and keep good driveability. It can be done obviously but not without a well rounded combo

spina74

iTrader: (12)

I shoulda been more specific, I see lots of guys on here with smaller cams making higher numbers. I ask the stock head/ported head question because I know I have way too much lift/duration for stock heads. I just don't want to still have way too much lift/duration with my ls6 heads ported. According to my machinist stock 243's max flow is at .550, anything higher and you lose flow. I'm not a machinist so I am just going off his words, but he is a very reputable builder in the area.

Tainted

iTrader: (9)

You may want to look into ls3 heads. They are cheap and make more power and the stock ls3 intake flows very well.

lemons12

iTrader: (71)

A nice set of cathedral heads will not only outflow ls3 they will give way better low and mid range and well as crisp and quick tip in power.

That stock cube motor won't like ls3s very much.

ShoddyHog

iTrader: (1)

rotflmao

1badeagle

iTrader: (9)

Stock cube motors do great with Ls3/L92 heads.

litle88

iTrader: (20)

^^^^^^^^
With shoddyhog

Tainted

iTrader: (9)

243s outflow ls3 heads? Last time I checked STOCK ls3 heads out flowed PORTED 243 heads.

Check this link. Pat G made 460rwhp through stock ls3 heads, CATS, stock intake etc. I'd have to say ls3 heads are one of the best bang for buck mods for an ls2! Granted they shine best on larger displacement, they still work great with a properly specd cam.

https://ls1tech.com/forums/dynamomet...p-446rwtq.html

LT1Formula007

iTrader: (66)

I think alot of your problem is with the intake, if you want my honest oppinion. the reason I say this is b/c my brother has a very similar setup and gained quite a bit of power with just an intake swap.

His setup is:
Rebuilt Stock Bottom End LS1 (ARP Rod Bolts) No bump in compression!
MS4 Cam
PRC Stage 1 LS6 heads
LS1 Intake
RPM 4L60E / PI 3800 Multi Disk Converter
10 Bolt w/ 3.42 gears
Car made 407 rwhp and 383 rwtq

He went to a FAST 92/92 and the new numbers were 444 rwhp 407 rwtq. He gained 37 rwhp and 24 rwtq and that's with his fuel pressure dropping fast during this pull. It fell from 60 psi to 35 psi, so they didn't make another pull bc the fuel pump couldn't keep up.
**The only change made was the FAST intake and TB.

As far as the LS6 heads not making power with a cam larger than .550" lift... FALSE!
My old 403 Stroker (11.1 compression) had STOCK untouched LS6 heads, other than dual valvesprings, And a 248/254 .615/.623 110 LSA Cam in it. The car had a 4l60e / Yank SS4000 Stall, 10 bolt 3.42 gears, and the car ran 10.99 at 125.6 mph with a lazy 1.659 60' (and it trapped 99.9 mph in the 1/8 and 125.6 mph in the 1/4 pretty consistently) The car weighed 3,440# btw. And That was with an unported FAST 92/92 setup as well.
And I'm certain the heads were holding it back a bit, but they still worked great. I'd think if they would hold anything back, the larger 403 stroker would've been way down on power before a 6.0L would have been.
I highly doubt your heads are holding you back that much. I'm betting it's in the intake. Or if it's an auto, you could be getting converter slippage and not showing the true #'s it's actually getting, to the ground.
Have you ever ran it at the track to see what it's et-ing/trapping?
That'll tell you everything you need to know. Dyno Numbers don't mean everything!

My buddy's "Bolt On" & "Cam Only" (Trqr v2 cam) LS1 and a 100 shot, (Trans Am) went 10.92 at 123 mph with 1.5 60'.... Stock EVERYTHING in the LS1 except for the Cam Package. LS1 Intake and Stock 241 heads are on it.
His NA #'s were 382 rwhp 363 rwtq (Best NA was 12.3 at (112mph - I think), and the car weighs about 3450 ish.

I think you should consider looking at the overall combo of parts and go from there. But theres more left in that combo for sure. Just gotta change things around and see what it likes.

Also, what type of dyno was it on? Some dyno's read significantly lower than others.

Tainted

iTrader: (9)

and FYI speaking on intake manifolds, there is a thread comparing a FAST 102mm intake to the stock ls3 and the gains were marginal at best. something to consider when getting ready to drop 700-1000$ on an intake alone...especially when a stock one can be had complete for $250

spina74

iTrader: (12)

The car is an M6, the last time I had it at the track I was trapping 116 with a full tank of gas and full interior, and the 3.42 10 bolt. I believe the car was ran on a dyno jet.

LS6427

iTrader: (2)

500 RWHP was done 10 years ago (stock cubes) with a Morgan Motorsports Aggressor 500 head/cam kit.....

Been done to death........its just gonna have a LOPEY idle....

TomtheRoofer was running 10's with that kit.........

.

LT1Formula007

iTrader: (66)

Thats very true, But if you ever plan to make any serious HP out of the setup, That LS3 Intake will need to be ported pretty good to keep up with the higher RPM's. But yes they can be had cheap and do work good! By higher rpm's, I'm talking 6200+ rpms. Which would come along with a big aggressive cam.

I personally would look into your setup a little more, Like I originally said.

But, For a budget "Stock head" swap... you can't beat LS3 heads and an LS3 intake. It's very cheap, makes great power, and has been proven to provide great driveability in cars as well.

** Another comparison, My friends 98 "Cam only" LS3 TA makes 441 rwhp and 425 rwtq, and he too was at the mercy of the stock fuel pump. Not to mention it drives like Stock, but with a lope at an idle.
He has nothing done to the car performance wise except a cam, headers, catback, stall, 92 mm TB, and a Volant CAI. Now a Racetronix Fuel Pump and hotwire kit! New numbers are not available just yet!

OP, The Dyno Jet has always been pretty fair to me. I've never seen any real big differences in Numbers from the 1 we've used here in town. But you never know. Being an M6, I too would think you'd have higher numbers for sure. Are you sure that your fuel pressure isn't falling off, or the clutch isn't slipping a little, or the tires aren't spinning on the dyno?? Again, theres too many things that can cause lower dyno numbers. But the 116 mph Traps are showing it's making decent power. If you keep the current setup, I would def look into a FAST 90/92/102 setup or a Victor jr, if thats the route you choose to go. But I think you'd pick up quite a bit... Just my honest oppinion!

lemons12

iTrader: (71)

What you guys laughing at?

You want to add anything?
They do ok.. definitely better options out there however. It is a stock gm casting. When they cam out people thought they were sent from heaven, not so much the case anymore.
They can't provide things, especially on 408s and smaller, that the Dyno doesn't always show.
I assume if you're familiar with that, you are with this too?
https://ls1tech.com/forums/dynamomet...k-results.html

Either we are reading posts differently or one of us is completely missing what is being said. I think we are comprehending the posts differently. Ls3 heads definitely outflow 243s.

There is zero doubt ls3s are a good bang for the buck. But a nice cathedral head will still out perform them.
Not to mention a street car would be much more fun with something else, especially on 408 and smaller cubes.. They simply can not provide the crisp quick tip in that the other heads provide, plus more power.
They work, but not my choice.

Remember though, rectangular heads don't need a huge cam like some cathedral heads to make big power. A 231/237 .600 114 is considered very large in a 6.2 ls3 setup.. That would be considered a slightly aggressive cam In a cathedral 346 motor.

1lejohn

iTrader: (9)

If you keep the 243's , MS4, and add a fast you should make in the mid 400's say 440-480. Not enough info on the rest of the combo. We made 450's with 243's MS3, and a Fast 92 on a 383 motor. That was with cheap long tubes and true duals. The tranny was a 60e with a 3500 stall. The rear is a 12 bolt with 4'11's.

Now compare that to the original 346 with the same heads Ls6 intake, 224 cam stock convertor , stock 10 bolt and 342's it made 420 ish.

You really can't one was set up to race the other was a street car.

The MS3 and 4 are top end cams with weak midranges. I didn't like it at all in the 383. It acted like it wanted a 5000 stall just to get moving. If you keep it the biggger intake and T-body will help, gears would too but not in the stock rear.

I disagree that the rect. port heads don't make power under the curve and are lazy. Our 416 makes much more torque and power then the other combos that I've had. It's not an apples to apples compare and I've never run aftermarket heads. The displacement helps but we are running a larger duration cam then the MS3 and its no comparision. The 416 does everything better. We are still running the 60e with a 4000 stall and the same 4.11's and true duals.

I'll put our car up against FI cars on a second gear pull its that crisp and fast revving. It does lay over in 3rd in the 6000+ range. This is the biggest draw back to these heads period. There are really no good intakes for them that fit under a stock hood. The Holly may be the answer but will require some work to fit.

lemons12

iTrader: (71)

A 416 would definitely compliment them better and help than low end and crispness they lack on the smaller motors. However, on a 6.0/383/etc they lack in that department. For a car driven a lot on the street, I wouldn't highly recommend that top end.