skinny z

Why the cam swap? The 294S is good for 470 hp with average heads. Possibly in excess of 500 hp with really good heads.
Have you physically measured the compression raio? Or is your 11:1 an assumption?

13TX

11:1 is rounded up. The math comes out to 10.72 with the amount the pistons are down in the hole, head gasket thickness, combustion chamber volume, etc. I want to do a cam swap mainly to get a roller in there because the single profile flat tappet comp is a tad primitive. I want to go with a split profile roller that's a Lil bigger and to give it more duration on the exhaust side and move the power band up some. Something in the high 240s and mid 250s at .050".

Podium

iTrader: (2)

Finding a 6 liter for that cheap from a junk yard is a rare. From first hand knowledge, ive seen them 1200-1500. Second, "slapping in a cam" in a stock 6 liter with bolts ons and making 420-450 is pushing it (it can be done but rare). Most lq4s make 380 to 400rwhp being cam only in ls1tech speak. The gift of the 6 liter is torque over a 346 ls1. Carbs do not make more peak power, it all depends on the intake.

z28fast1 has point though. You wanna beat the new motors? Gotta pay to play if you wanna be streetable. Ive had many built ls cars. When i bought my iroc, I thought about building a sbc with afr heads and the works. i did more research and found out that I could put about 5k into a sbc and make less power than my ls1 (stock self ported 5.3 heads on mustang dyno through a ls7 clutch and a moser 9)that put down 450rwhp. That might only be on average 50 rwhp more than a hot street 350, but you also have the mpg and tubning advatages of the lsx. I spoke with Tony Mamo and he even said you cant even begin to compare a sbc/ltx head to an lsx head.

cuisinartvette

Let Chris put togehter a H/C combo for you he will nail it the first time

Impressed with the Coyotes they are a strong running and great looking car

Wish GM would build a similar motor

13TX

By Chris I assume you are meaning Chris Speier(sp)? I was already looking at his heads, so we're definitely on the same page. I'm definitely not gonna skimp on the heads. I agree on the Coyote statement. Excellent technology.... They run outstanding. Makes an old school pushrod motor seem like fighting with one hand tied behind your back.

Dominic Sorresso

They did. It was the LT-5. GM Powertrain basically killed it because Lotus (which was part of GM at the time) developed it. Perfect example of NIH. NO question the Gen 3-5 SBC are a incredibly engineered for power density, efficiency, and weight. In a way it's a bit like what Porsche has done w rear mounted motor.
They've tweaked the hell out of it to make it work well for them. GM has done the same with OHV. Remains to be seen whether it's at the end of its design potential.

cuisinartvette

Had a ZR1 yrs ago fine motor
Sure with GMs tech in heads they could put together something stellar these days but the bean counters wont have it. You couldnt kill an LT5.

To the poster was referring to Chris Straub?

Comment on the LSx-Gen 1 heads....worlds apart esp the better aftermarket ones.

If it were me to "keep up" build the biggest displacement motor you can with power over a broad range that should take care of most of whats out there.

Throw a snail on it if you get bored.

Dominic Sorresso

Mercury Marine built the LT-5 at their Stillwater facility in the 90's. If you haven't seen it, now they have introduced their own rendition of a DOHC motor.
I can see some similarities.

http://blogs.hotrod.com/?attachment_id=91281

13TX

Thanks for the input. Thought about going big block and I may still at some point, but I'm gonna get everything I possibly can out of my old school small block before I go down that road.

rb85TA

13TX, It sounds like you have a decent running combo (they can always be made better) , and I have to agree with what the guys are saying (definitely gear bound by the tranny) your engine is similar to MY-92-RS but he is running a t5 with 3.42's and went 11.78 @ 116 (mph May be a little off) , that being said, I think you should put a TKO 600 in her (with a good clutch & aluminum flywheel) to go with the new AFR'S and a solid roller with around a 260/268@.050 duration

rb85TA

Bump the compression up a tad (right@ 11:1), she will be altogether another beast! (You will probably have to retune your suspension , but If you're any good with a standard the mustang guys gonna flip! !

big hammer

5.0's are a different animal. not unbeatable, just different.

first off, they're very feminine on the low end. that's why they always want a roll. like a supra.

2nd, they have a 6 speed, but 5th is 1-1. they're a single overdrive. the 5.0 depends on aggressive gearing.

3rd, TIVCT. (twin independent variable cam timing) this is huge. this allows the tune to not only advance\retard the cam, it allows on the fly changes to the LSA. (lobe separation angles) this is often way over looked in old school engine building. it's a good part of the reason with a tune alone the 5.0 can rev to 7500 rpm. a tune on a 5.0 is almost more like a cam swap, but not quite.

Dominic Sorresso

4th. 2 smaller valves will breathe and exhale more efficiently than one large valve.

cuisinartvette

x2
If youre goin to bump up the compression than just stroke the thing, shoot for at least 11.5:1 220 AFR head single plane and a 256-260ish@050 cam that coyote wont come anywhere near you;but thats money..lots
Course at that cost you could get a 496 with way more power/torque in a crate.
Gave up on trying to go fast with a 350 yrs ago going bigger was the best thing I ever did.

rb85TA

Well if you stroke it, a 3.875" in a 350 block (GM) is as far as I'd recommend, even then you're looking at a lot of clearancing!
But a 6" rod 396 cubic inch mouse with 11.5:1 comp, a solid roller 256/264@.050 and around. 630-.680 lift with a 1.55-1.6 ,shaft mounted rocker... that DOG WILL HUNT!

rb85TA

Oh, and if you're bound & determined to keep the th350, look into a gearvendor's unit

big hammer

Well yeah.. You're racing a 400 hp car vs a 350 hp c5. Try that against the c5Z and you'll get crushed.

Dominic Sorresso

A stock 90-92 ZR weighs nearly 300lbs more than a C5 and made 375 at the crank. So on paper, I'd call that a draw. A 93-95 ZR made 405hp which is the same as an LS-6 C5Z. I wouldn't argue the C5 Z would be quicker particularly from a dig, top end however I think would be a different story.

big hammer

C5Z's have ran into the 11's stock around 118 mph. They're top end monsters. Guys will shift them close to 7000 rpm with stock internals even though they're just a lowly pushrod engine.

Dominic Sorresso

I'm not talking about the last 1/8 mile for top end. A stock 375hp ZR-1 will trap 110-112 in the 1/4. You're saying a STOCK C5Z will trap 118? Really? That would take about 400+rwhp from a stock LS-6.

big hammer

It Takes good DA but it's been done.

I know what you're saying about DOHC engines pulling good speeds due to their RPM. And that's why TPI cars trap low for the Hp they have. But newer pushrod engines rev out well too. The ls7 has a 7000 rpm redline stock.

Dominic Sorresso

And LS7 motors are dropping valves. Look at the lift on those camshafts. The specs on an LT-5 camshaft are less radical because of how well 4V breathe. The LS7 heads are great cylinder heads, but at the end of the day a 4V motor will lose less hp over the rpm range while an OHV motor will nose over after peak. That's just the physics of it. It takes very little to get a stock 375hp LT-5 to a ~ 500chp with stock cams, cylinder heads and still 5.7L displacement.
I've seen a 427 LT-5 wipe a 427 LS-7, and the LT-5 still idles at 875rpm.

big hammer

So You're comparing a heavily modified lt5 to a stock ls7 now?

Dominic Sorresso

I'm comparing cubic inch to cubic inch. But I could also show you a modded 5.7L
LT-5 that runs 11.0s at 129mph. Full interior, 3.45 gear, stock bottom end, stock heads (nothing else available), pretty much DIY.

big hammer

That's cool. Ls7's have ran 9's around 138 mph with bolt ons.

big hammer

There's also been a c5z that ran a 10.1 with bolt ons. Another guy I know ran 11.0 @ 131 with a stock internal ls6

Dominic Sorresso

I'm happy for you.

luvofjah

iTrader: (2)

1 car length against a car that is "new" (not 23 to 33 years old), with Direct Injection, etc... I say, that's great! There is always gonna be someone faster...

Personally, not being biased towards third gen, when I go to shows, I much more appreciate the older cars that have been taken care of than a new one someone with a lot of $$$ just bought... Gee, I could see the same thing at the showroom... The older car, let's see what they did, how it got taken care of, this guy is a car guy! (or gal!)

No shame in 1 car length... to me... I'd be pissed if I was the Mustang Guy

Rafael

RS Chris

Ah yes the ole "I know a guy, talked to a guy, bumped into a guy" story.

dannyboyemt

There is video of said LS6 car running low 11s@131mph. He can post them if you ask nice. Just head over to ls1tech, you can find all that stuff there. Bighammer isnt lying.

dannyboyemt

The amount of LS7's dropping exhaust valves is less than 1 percent. From what i could find its the exhaust valves(possibly the valve guides themselves)not the cam lift.