aluminum 383 or iron 408?? Is the extra cubes worth the weight?? Ill be spraying a 150 shot every now and again. Im going with the eagle stroker kit that HPE sells both are the same price.

 

If you can overcome the extra 100 pounds then it won't be much of a comparison. Do a few weight savings tricks and you should make up the weight pretty easy. Then again, the numbers put out by both are pretty similar. You just don't see alot of 383's. Personally, I'd stay with the aluminum, but lots swap for the iron now days. Either would be a good choice. You'll always be slower than me, so you might as well be pissin in the wind.

 

I had this same decision. I chose iron of course. My rationale was it takes approx 20 to 25rwhp to move 80 to 100lbs off the line. I looked at the 96 F-body weights and compared them to the LS1's and the weight difference was around 85lbs. The LT1's got around just fine with the extra 85lbs. A 408ci will make more horsepower/torque than a 383ci. Plus, it only takes minor weight reduction to lose 85lbs. Of course the losing of 85lbs depends on your starting point.

Now that we have the LS2, you might want to think of that route. You will start out with a 6.0L block and all you will need is a bigger crank to get the cubes you want. With a 4.00 bore x 4.00 stroke you will have a 402ci.. You get the best of both worlds. Unfortunately the LS2 was not an option when I was making my decision. You have the option..

 

Weight saving I already have once I make the decision. I have a BMR K member and lower control arms. Will also go with a light weight battery. Any guess on how much more hp and tq were talking about with the 408??

Jason might be faster if you ever get around to installing your parts

 

Just looking at the 383ci'rs on this board they dyno between 440 and 485rwhp and about 440rwtq and 475rwtq. With the LSX the #'s could be higher. Now we do not have too many dyno #'s from the 408ci cars, but on avg I would think between 490rwhp to 520rwhp and about 490rwtq to 500rwtq. The only data I can go by is the #'s from 396ci cars on this board and a few 408ci cars that shared that dyno information. APE put down over 500rwhp with a 408ci car and Futral Motorsports have put down 517rwhp/490rwtq on a 397ci car.

Also, your dyno #'s will depend on how radical you are willing to go. You would have to go more radical to get the 383ci to dyno as high as a 408ci with similar mods. Therefore sacrificing driveability. Now these are all just my opinion. I have been in two iron block cars. My old 95 TA and 383LQ4SS's car. I did not know my 95 TA had a iron block until I started modding it and I was told. In 383LQ4SS's car you cant tell at all. It drives just like it had an alum in the car and this was b4 Al did any weight reduction.

 

That would help wouldn't it? But really, I'm still waiting on a few things and I'll be ready to go. There is really only one way to look at the situation you are in: Dyno numbers vary so much that it is hard to get a good answer. There are so few 383's and 408's running that it is hard to get solid numbers. The way I look at it is, if done properly, more cubic inches will equal more power across the board. You've done the weight reduction, so the only downfall will be adding back a few extra pounds. You could always buy a C5-R block!

 

The deciding factor for me was that my heads ended up being fubared. Since I needed new heads the IRON would have been the same price as the 383. I figured the iron would be stronger and be able to rev higher than the stroker 383 so I decided 408.

 

Why not go 406 in the aluminum (4.250 stroke) . Does it get too tricky when stroking that much? I know additional clearance may be necessary but are the blocks unreliable at that point?

 

I would stay with aluminum. That is a pretty big weight difference hanging off the front of the car. I personally have never heard of an alu LS1 block blowing up simple because it is made out of aluminum.

 

The 6.0 truck block weigh's 72 lbs more than the ls1 block, if you had them both torn down bare. Relocating the battery would almost be enough to rebalance the car. The only real deciding factor is how much $$ do you want to spend? I think that the only place that I have heard of the aluminum block being an issue was with extremely high amounts of boost. I remember hearing about someone lifting heads off the block, and the problem ended up being the head studs actually pulled up out of the threads in the block. That's the only failure I recall, other than the guys with resleeving issues, but that's a whole different issue. LS2 would be worth looking at too, unless you are doing this project immediately.

 

4.250 is getting way out round. Your bore will only be 3.905, so surpasing the size of your bore gets you more side load. A 4.00 will get you 383, 4.125 will net a 396. I would be weary of the 4.125 in a 3.905 application, but there are people using them with success. I think his main concern is cost. The eagle cranks can be had for $850, but require more machine work than others which usaully adds back into the price. In the end you still come out cheaper. Lunati is the only one I know that has a 4.250 stroke and there cranks are around 2k. So there is another option Dan, aluminum 396, if you can find a 4.125 crank for a decent price. If you'd like something better than the eagle, there are Cola 4.00" stroke cranks for LS-1's on ebay right now for around $850. Made in america out of our 4340, not the brittle chinese stuff.

 

The 4.250 sroke is doable but probably not as strong with the pistons you need to run to keep everything in the bore when pulling it down that far. The C5R could maybe use it but the normal LSx blocks cylinders just aren't that long. Then there's the fact as Beast said that only big dollar cranks are being made at that stroke. I've used Eagle in 1000hp drag engines and never had a problem. The Cola would be fine too but most of their regular SBC stuff is anchor heavy. Haven't seen their LSx stuff yet.

 

just for reference, my 383 put down 485/475 with the 78mm LSX, now has the 90 and should be around 500 rwhp. with a 'small' 236/232 .600 cam.

 

Check out http://www.scatcrankshafts.com/ they will make any crank for you (Speak with Peter Leid, tell him David McAfee sent you). He told me there is no price difference in the crank stroke but as Beast said machine work and pistons will cost more.

D

 

Im leaning more towards the 408, im hoping to get around 500rwhp with the mods in my sig. I was also thinking of getting the cam APE put in there 408 to accomplish the 500 rwhp. Plus I think the lightweight suspension mods i do will help with the weight offset.

 

Damn man, we have pretty similar set-ups. Who's gunna get to 500 first and how many cubic inches will it take to get there?

 

Take a look at my sig. The AS S3 heads and a APE short block made me 503rwhp with a very similar cam.......I dont think you can go wrong with APE.

 

Why not a 396 ?

 

That is a nice setup. I would rather have a aluminum motor that puts out 485 than an iron block that puts out 500. Yeah, you can you can relocate the battery and get a light k-member, but you can do the same with an alu motor and be so much lighter. One of the biggest things that attracted me to the ls1 is that it is all aluminum. I could see the advantage of iron if alu blocks had a problem of failing because they are weak, but I haven't seen it. Even on boosted and sprayed motors. Does anyone personally know of a ls1 that blew because of the material it is made of? LS1tech myth or fact?

 

11Bravo, I was going to reply exactly the same I'm no LS1 expert, and forgive me for ever saying this, but what about all of those little ricers suping up their motors. Most of those motors are all aluminum too, arent they? It's trippy to hear my neighbor's kid tell me what some of his friends are doing to their motors (boost, nitrous)

D