LS1LT1

Really? I'd sold my Northstar DeVille Concours with over 120k miles on it, didn't leak at all.

ALBUNDY

Check info:http://autospeed.drive.com.au/cms/A_1569/article.html

Paul in VA

Hi:
Just a thought... Cheverolet did make a high revving V8, the LT-5 with dual overhead cams. I think the factory redline was in the 7600 RPM range. Old engine but it is able to rev and you would still have a Corvette engine in a Corvette.
...Paul

glass slipper

I had a Concours also that I sold at 140k miles and the new owner went to 180k (before he totaled it ) with absolutely zero oil leaks or any engine problems for that matter. I've never heard of any thing like that and am calling BS on his post. In fact, all I've ever heard is how "bulletproof" those engines are easily going to 200k with no problems.
I had the most fun with that car at the expense of Mustang GTs...it was funny to see the look on their faces after I blew past them. One had a passenger that was laughing his azz off after seeing his buddy get beat bad by an "old guy" in a Caddy.

glass slipper

While the LT5 is right up there with a lot of great engines, let's not get too carried away. The factory redline is 7000 RPM with the rev limiter set to ~7100 RPM. You are correct that it's able to rev though, plenty of people have raised the rev limiter to 7500+ RPM with the stock bottom end. It's a beautiful engine that makes the sweetest sounds at full throttle/high RPMs...

It's also physically bigger (taller and wider) and heavier (like ~200 LBs more) compared to an LSx engine and would require a much higher hood to clear the engine. I have a '77 coupe w/L48, '93 ZR1 w/LT5, and '99 coupe w/LS1 and like each one of them equally but for different reasons so I'm not knocking on the LT5. Actually, while the body style of the '68-'82 is seductive and the LSx cars just do everything really good, there is something about the sound of the ZR1/LT5 that is "Simply Irresistible"...ok, I guess maybe I like the ZR1 a little more and it would be the one I'd keep if I could only have one. I'm just glad it's not against the law to have more than one!

RWTD

While the Northstar is a terrific engine, many GM serviceman will tell you that many of the pre-new ones have been service shop nightmares.

valdeztke

The northstars are also pretttty wide.....I dont think it would fit in the C6 (nor would I want to put it in a C6 either )

ALBUNDY

My 96Eldo has no oil leak but I'm sure he's refering to the half case oil leaks that have happened to other N*s.

CPhelps

http://www.katechengines.com/street_...e_packages.php

"KAT-A4725 Sneak Attack LS7: 5.7L, 346in3
With an 8000rpm redline, this crate engine is ideal for that "sleeper" ride. Package includes a Katech sleeved LS2 case, Katech forged piston-rod assembly, forged crankshaft, LS7 cylinder heads, and an LS7 derived valvetrain coupled with Katech specified camshaft.
2 Stage wet sump oiling system"

NOT cheap however, but swapping in a Northstar and getting it to work well reliably wont be either.

corvetterich

Hey guys thanks, I've been out of town last week , I see a lot of new info so thanks Albundy & Cphelps... I should have my questions answered by next week.. I will let everyone know where I'am at with this idea.....

Phimosis

One thing no one is talking about in this thread is piston velocity.

Conventional wisdom says that with today's alloys that ~5,000 feet per minute is the limit that an engine's bottom end can hold together.

Formula: rpm x 2 x stroke (inches) /12 = feet per minute (fpm)

Examples:
'07 Z06 = 7000 x 2 x 4 /12 = 4667 fpm

'07 LS2 = 6500 x 2 x 3.62 /12 = 3922 fpm

'07 Cad LC3 (469hp) = 6700 x 2 x 3.31 / 12 = 3696 fpm

'07 FIA F1 2.4l V8 = 19,000 x 2 x 1.56 / 12 = 4940 fpm

'07 Ducati 1098s = 11,000 x 2 x 2.55 / 12 = 4675 fpm

Using this formula, a Z06 is pushing it's limit at 7,000 rpm. An LS2 has room for 7790 rpm (at 4700 fpm). A 4.4 liter Cadillac LC3 motor should be able to tolerate 8520 rpm (at 4700 fpm).

The Caddy motor at 8,500 would be similar to a Ferrari F430 (4.3 liter V8) or BMW's 5 liter V10, which both DO hit 8500 rpm.

The difference is that the American cars are not exotics. If you used titanium rods and valves like Ferrari and BMW and reworked your LS2 or LC3 you just might tolerate those speeds.

Even if you did, you would need aftermarket electronics to accomodate the rich fuel curves you would need in those rev ranges and then likely not meet your local emissions regulations. Additionally, your stock heads/ports/runners are tuned for lower rpm and you would lose a good chunk of your high end power unless you had them modified too.....Then that would lead to poor low rpm performance, mileage and emissions. That is why you see exotics with variable runner lengths and such.

And one last thing: The reason why Cadillac is using such a low rpm range on that short stroke motor is that much of the country can only get 91 octane gas and with a supercharger in 6000+ rpm range, detonation becomes a life threatening complication of forced induction. If you pushed that motor to 8000 rpm, you would surely get detonation. Then you would have to retard timing / back your boost levels down, negating your rpm increases.

In summary, I think your best choices are 1) leave your motor mostly stock and be happy that traction control has already saved your butt dozens of times. 2) do a Procharger installation. It is the cheapest hp per dollar spent. I had a Kenne Bell supercharger in a Mustang Cobra and is was too explosive at low rpms. The torque curve on the centrifugal superchargers is more linear and is easier to control when exiting corners and coming on the throttle. 3) Tweak your LS2 motor for more rpm and air flow. This will be more costly per hp, but you'll start pushing that 8000 rpm mark, making music to your ears. You'll hate yourself in two years when your new car needs to be smogged.

:-)

-Phim

LS1LT1

....and Chevrolet (ie: Corvette Z06)

What was that again about American cars not being exotics?

glass slipper

The Northstar already fits in a "C6"...it's called the XLR with the XLRV getting a supercharger.

glass slipper

You don't need any richer mixtures at higher RPMs than lower RPMs and you're in open loop at that point. Emissions checks are done in closed loop where the A/F ratio is kept at lambda=1 or stoichometric (14.7:1).

Also, I don't understand your statement concerning high RPM causing detonation. Higher RPM decreases the possibility of detonation by reducing the time for the gases/end gases to react...one of the benefits of increased piston speed at higher RPM. While detonation can occur at any RPM, it's more likely to happen at lower RPMs. I think you're getting confused with the exponential increase in boost with a centrifigul supercharger (like your Procharger), that's what will get you into detonation when you increase RPMs. Let's say your making 1 LB of boost at 2000 RPM. That turns into 4 LBs at 4000 RPM and 9 LBs at 6000 RPM, still manageable on pump gas on a stock engine. But at 8000 RPM, we'll have 16 LBs of boost which will almost certainly cause detonation...however, it wasn't the increased RPM that caused it but the exponential increase in boost associated the increase in efficiency of the supercharger at higher RPMs. If your logic is followed, we wouldn't have 18-19,000 RPM F1 engines.

Phimosis

Hmm nit picking I see.... I didn't say "richer," I said rich. If you spin an engine 25% faster than it's design speed, it will require 25% more fuel fuel than stock and you will have 25% less time to do it. You'll soon run out of dwell time from your injectors and your mixture will lean out. That's why many aftermarket supercharger kits include bigger fuel injectors.

Ok. I'm not confused. I'm not referring to centrifugal superchargers. I had a Lysholme supercharger that would deliver 6.5 psi of boost from 2000 to 7000 rpm. I only got detonation above 6000 rpm. It has to do with the rate that the air is being compresed. at 7000 rpm with 6.5 psi of boost, the air has to be compressed twice as fast as at 3500 rpm with 6.5 psi of boost. Compressing the air faster leads to higher charge temperatures, which leads to predetonation......ingnition without spark. Positive displacement superchargers are notorious for imparting large amounts of heat to their air charge at high rpms. All of the commercially avaialable kits have timing retard chips that retard ignition timing while the engine is under boost to try to help eliminate this problem, but it still persists when the charge temperature is too high and the mix ignites without spark. Similarly, all modern sport bikes use timing retard at high rpm. A 13:1 engine on pump gas won't survive 15,000 rpm with spark before TDC. Juust Google "timing retard supercharger detonation" and you'll get plenty of info on this topic.

-Phim

Phimosis

Absolutely true! That's also why the Z06 motor is pushing the 5000 fpm envelope. Dry sump oiling is also pretty exotic for a road car.

I was referring to the original poster's debate between his LS2 and the Cad LC3.

:-)

-Phim

Mez

I can't see this swap making any sense.

Here are the things I would factor:

Power? You should be able to make more power with the unblown LS2 than the Northstar for the same money.

Weight? I doubt there is any significant weight difference. The all aluminum LS2 with cam in block has to weight less than SC Northstar.

Size? Northstar has to be bigger with the DOHC and blower.

Cost? You can build a 500hp LS2 for a lot less than swapping in the SC Northstar.

Simplicity? LS2 a lot less.

RPM? With the right cam, springs, and valves, you can rev the LS2 over 7,000 rpm.

Reliability? LS2...fewer parts.


There is HI-TECH and there is WHY?-TECH. This swap fits the second catigory, in my opinion.

corvetterich

Hey guys , Back in town again.. I've been reading posts tonite, Think we're getting off track, Mez.. Please read the beginning and you will see why I'am looking to do this swap... I have layed out my thoughts to a vendor and he is checking afew things before he commits... I should hear this week.. I will be in town next few weeks, so I will be able to respond as soon as I hear... I don't want to repeat myself as to why I feel the 4.4northstar would be better, But this vendor is feeling the same so far.... Thanks guys , I will report asap when I hear more...

LS1LT1

True, and we've all responded as to why we disagree with some of your reasonings/feelings.
There's nothing wrong with pushrods.
Regardless of their multiple cams and valves, Northstars don't necessarily wind any higher than LSX motors do anyway and will likely always make less torque.
Tech simply for the sake of tech doesn't make something better all by itself, the faster/more powerful car usually still wins in the end.

ALBUNDY

Here's two of the vendors/performance help.

http://www.d3cadillac.com/

http://www.chrfab.com/

chrfab project car. N* in a Corvette.

Quote:Ever seen a Corvette with a Northstar engine?? Well I hadn't either, and really wondered if the guy was ______!! He won 8 out of 8 races with this combination though. Tom Classon from Europe.