old motorhead

iTrader: (10)

I still remember my last ride in a Gen I camaro with the 302 Z motor. The thing would rev to the moon and do it all day long.

DAlgozine

I'm interested in putting together this very engine combo. I'm a road course racer looking for quick revs and sustained higher RPM's. By class rules, NASA American Iron, we are HP and TQ limited based on the weight of our cars. Which means, ideally I'm looking for about 340 RWHP and 355 RWTQ. Not huge numbers, but fast reving and very reliable is important.
The LS2 block and 4.8 crank and rods appears to be an excellent combo for my needs.
Anyone have knowledge of this being completed? If so any details available?
Would a standard LS2 piston work with this combo? Expected compression ratio?
Any info would be appreciated.

Dave

KCS

iTrader: (20)

I don't want you to think I'm trying to talk you out of it, I'm not. I'm just more or less arguing theory...mainly because I'm bored, haha.

If you're not planning on taking advantage of cheaper fuel, then I don't see much reason not to do what you're thinking of doing. I think at the same power levels, that is the advantage of having a larger engine underneath that blower...but I don't know that it'll get the benefits you're expecting, at least in any significant amount. I hope it does though, sounds like you may get results comparable to the mod motor Cobra guys.

old motorhead

iTrader: (10)

An LS2 piston on a 4.8 crank with 4.8 con rods would have less comp ratio vs the same piston with the longer stroke. Less swept area. Someone would have to do the math to get compression ratio with standard pistons and less stroke. I'm hoping off the shelf pistons will get me close to 10.5 c/r. Maybe a set of pistons designed for 12.5 in an LS2 would get me near where I'm wanting to be. No reason this won't work for you or me. May be difficult to balance....don't know.

old motorhead

iTrader: (10)

Don't mind the arguing a bit. I'd rather cover the possible "gotcha's" before going any farther. They're pretty cheap at this point.

Torlow

If you do this I predict:

- it will cost you much more than any potential fuel savings to do the build right

- if you don't carefully plan and execute this non-standard build correctly, your engine longevity will be greatly reduced

- you are likely to see increased fuel consumption due to loss of low-end torque during normal driving

- you will make less power (maybe not much but less) than with a standard stroke

Daryn

iTrader: (19)

built your motor man and when it yields great results u can slap the haters in the face with it


ive personally ben wanting to run a 6.0 with forged 4.8 parts simply for the fact that i like to rev past the moon. with the right setup... 8500 rpms is easily do able.

old motorhead

iTrader: (10)

Thanks for the critique.

What am I missing to do the job right? Hoping to use stock 4.8 rods and crank and off the shelf 6.0L forged pistons.

+-330 cid has been powering 3500lb vehicles around effeciently for a while. I can't see where this is a problem.

You don't use all of the torque available on a 330 cid engine just to move the vehicle around. I know, at WOT, there won't be as much torque available vs a bigger engine. Blower will more than make up for the lack of CID when necessary.

Hans Grüber

iTrader: (2)

The valve train is the RPM limiting factor, not the piston speed (stroke) !!

8500 rpm with the stock cast 4.8 crank and rods is a stupid idea anyways. So you'll need to go aftermarket. And I don't know of anyone that makes forged 3.268 stroke LS cranks.

The piston speed difference is also negligible. 77 fps for 3.268 and 85 fps for 3.622.

To run 8500 rpm with any reliability, you'll need to spend huge money on Ti valves, lightweight rockers, pushrods, lifters.

scatillac

iTrader: (12)

I'd rather see a 4.065x3.268 combo with good heads and a properly-sized turbo.

You contact the folks at Katech. I believe that the earlier CTS-VRs were 4.125x3.27, and of course, they were N/A. The cars also had a sequential gearbox to take advantage of the motor.

The team spun those things to the moon until the SCCA reined them in with rev limiters and an intake restrictor.

http://www.cadillacfaq.com/faq/answe...vrsccaform.pdf

DAlgozine

Started a seperate thread, requesting info
https://ls1tech.com/forums/generatio...l#post12572479


Looking for more detailed info on the various specs of the LS engine family. Here's some of what I have

Engine.......Bore..................Stroke ..............Rod
4.8.......3.78" (96mm).......3.27" (83mm)........?
5.3.......3.8 " (96mm)........3.62" (92mm)........?
5.7.......3.9" (99mm)........3.62" (92mm).......6.098
6.0.......4.0" (101mm).......3.62" (92mm).......6.098

Anyone no where to find detailed engine specs on the LS?
Looking for rod lengths ?
Piston details, such as wrist pin location, are they all in the same location?

MAC4264

Do it! You can't get much good info on short stroke on this website as 95% of the people here are very misinformed about it. Let me show you a few examples.

Callies will make any stroke between 2.7 and 4.25. Sonny Bryant will make any stroke as well just to name a few off the top of my head.


You showed your level when you posted Jon Stewart.

People are scared of it cause it is outside the box and not the same old cookie cutter 402+ inch motor with so and so latest greatest head on it.
Starting to get pretty boring. BTW turn the stocker in my signature 7500 with stock rockers hydraulic rollers and behive springs nothing to fancy.

Hans Grüber

iTrader: (2)

I should have clarified, 3.268 is not a standard stroke carried by any manufacturer that I'm aware of. Sure they'll custom make it for a premium $$$, and add to that the unique length connecting rods that it will require $$$.

I'm all for doing something unique (I'm doing a Catera V8 conversion), but I really don't see any benefit of doing this.

silvergto115

They are all in the same location, same size, the only difference being it having either pressed or floated pins.



Build this damn thing already. It will meet all of your expectations.

DAlgozine

I found some more info for those that are interested. It appears the swap can be completed without custom parts or special work.

Any leads on some non-custom parts, such as:
forged 4.8 crank and rods
LS2 block (aluminum Gen IV 6.0L )
Chicago or Indianapolis engine shop that specializes in LS engines?


http://www.gmhightechperformance.com...ory/index.html




http://forums.popularhotrodding.com/...ext/page2.html

(about halfway down the page)



http://www.enginebuildermag.com/Arti...all_block.aspx



http://forums.hybridz.org/showthread.php?t=87947

(general LS info)

Bilster

iTrader: (21)

You might want to consider this route....
Find a dirt cheap 4.3 iron short block. It will, of course, have the shorter stroke/long rods you are looking for. Bore the block to 3.90. Use a set of good LS1 forged pistons and your set. The stock compression height for the LS1 piston will be correct for the 4.3 crank and rods. By doing this, you will have a cheap stout iron block. If your not happy with the combination, you won't be out much money. Drop in a forged LS1 crank and rods and be done with it.

I have done a few of 3.25" stroke cranks, 6.25" rods in 400 Gen 1 SBCs. Get help from your cam manufacturer on cam selection. I know short stroke/long rod Gen 1 SBCs do not run best with wide lobe separations but a wide lobe separation is what you want in a supercharged/turbo motor as you proposed. I wouldn't have any idea how to reconcile that dilemma but I bet a quality cam manufacturer would.

KCS

iTrader: (20)

LOL, my level? Haha, give me a break.

No one is scared of an engine like this, and it's certainly not a new concept either. The concept is about as "outside the box" as playing darts with a blindfold on.

At first, he sounded like every other goofball who wanted to destroke their 346 so that they could theoretically turn 9000rpm no sweat, but reality is a bitch! If he was really concerned about power, he seems like he would understand a bigger engine/blower would be better option. If he was really concerned with fuel economy, he would likely just take the blower off, or just sell the truck and buy a Prius.

It sounds to me like he has some money to burn, and it's just a little experiment to see what happens more than anything. In that case, I say go for it, but the way the idea was presented in post number one left me looking like that picture of Jon Stewart.

This isn't a 2.8hp/ci engine, so what do you care? It's not a "real" engine to you...

old motorhead

iTrader: (10)

Where did I come off as some "goofball" that wanted to turn 9000 rpm? What's goofy about sizing an engine to the job? I understand a bigger engine is capable of more power.....who doesn't? What would taking the blower off have to do with the engine being more effecient? The beauty of what I'm trying to do comes with making good power (because of the blower) and not burning too much fuel (because of the smaller engine size and lighter aluminum block). If you can make the power you're looking for with less engine size, it will burn less fuel. If that's too far out in left field for you, please accept my appologies.....again. Please review post #7 in this thread.

Again, the engine isn't going in a 5000 lb truck. More like 3500 lb car. That 6.0L in my sig is doing fine and is where the idea came from to do this build. I could put a 7.0L motor under that blower and it wouldn't make any more power, just eat more fuel. The blower only has so much capacity. It can provide provide enough air to make similer power in a 5.3L motor with the same or slightly higher boost.

I don't have money to burn. If this thing goes together like I hope it will, nothing more than a rebuild with forged pistons will be involved.

KCS

iTrader: (20)

Sorry, I didn't mean that as an insult to you. I was saying at first, like post #1, that is how it sounded. The majority of the people who want to destroke their engines are poorly misguided. It is goofy think they will be able to turn 9000rpm in their street cars, have a great power curve, and drive it everyday, while getting great fuel economy because it is a smaller engine. I've heard it a million times now, and you didn't seem any different judging by the first post. Once you elaborated more throughout the thread, I saw that my first impression was wrong.

Engine efficiency is a very vague and ambiguous term, and doesn't always equate to fuel economy. Some people look at Wankels as efficient engines... Since fuel consumption is directly related to the mass of air an engine consumes, taking off the blower, effectively reducing the amount of air ingested, will decrease the fuel consumption. From what I understand about engine dynamics, engine size is only slightly related to fuel economy, with respect to friction. It's more important to look at the amount of air being ingested and even BSFC numbers. Even though it is a smaller engine, it will be ingesting the same amount of air thanks to the blower, but that is at WOT and high loads. Cruising and part throttle may be slightly different, but how much, I couldn't tell you, because that would even take into account driving habits, as previously mentioned. It's really hard to say without tightly controlling all of the variables.

MAC4264

Yeah but he is at least willing to try the small stroke so my hat off to him. This tread caught my eye as I was looking at the other thread of the Edelbrock heads. As for the real part he isn't going to race in a weight to cubic inch class or claim he is building an all out N/A motor either. As the original guy stated if you don't like it go somewhere else. There are plenty of 402 threads to go see. But you must be interested or you wouldn't keep coming back.

Stop and think about it. A new ZO6 made 505hp at 427 ci. A new ZR1 made 635 hp at 370ci (Alot less stroke and a hair of bore) with a blower. I wonder why GM didn't make the ZR1 a 427 with a blower and just detune it to make 635. Oh yeah by the way I consider both of those real motors cause the mass produce them so people can use the technology from the 2.8 hp/ci motors.