383 vs. LT4

Well, over the past while I have been doing more serious in depth research and have found that my LS1 plans probably won't come through. Sad for me, but oh well.

In looking however, I have found it to be much more likly to get around a '94-'95 LT1, and have been researching power adders for that.

I think the two starting blocks, besides basics such as intake and exhuast, etc. are either a 383 Stroker or the LT4 conversion.


Advice on which road to pursue? Cost vs performance plus drivability?

Thanks.

Here the two I found:

Summit, LT4
http://store.summitracing.com/default.asp?target=partdetail.asp&part=NAL-GMP3287-1

RPMmachine, stroker
http://www.rpmmachine.com/350-chevy-forged-stroker-sb.shtml


MPG is also a consideration.

personally, i dont know what research you found that makes you think the LT1 based engine are a better starting point than the LS1 based engines. I would much rather work from the newer LS1 engines to make power. there are compareable mods for the LS1 to the LT1 mods you are looking at. But the LS1 will be more reliable.

Age and price mostly. Same parts, but $10,000 cheaper car to start from. Plus, I am not making a drag car, at least not right away. And lastly... I guess I just like the original 4th gen look a little better.

Well I found an awesome head and cam guy, his name is Lloyd Elliot.

Check this out, tell me what you think:http://eportworks.com/LT1LE2.htm

Only thing I don't know, what are 1 3/4 LT's? I get the fact you need the intake system, TB and whatnot, and exhaust.....

Oh, it means Long Tubes right?

you get a gold star kid ;)

Hahaha. Thanks, I think.

So does anyone have any advice or ideas?

I just like the original 4th gen look a little better.

right on man!!!

:icon16:

I think the first stroker crank isnt for an LT1, i was also interested in a 383 crank and have already done alot of research, here was a link i used
http://www.speedomotive.com/LT-1%20CHEVY%20383%20KIT.htm

but you can also try golen for the shortblock strokers, they also sell a 480hp 520lb longblock, but as far as just the crank and accesories, above is the better plan.

Work on the heads first, then stroke the motor. If its a matter of dollars and cents and you can only do one route or the other I'd say sink your money into the heads.

I wouldn't exactly settle on the LT4 heads though - those castings with 2.00" intake valve flow around 245 cfm at .500 lift. I'd pick up a set of bare LT4 castings and go for a port & polish job with possibly a 2.02" intake valve - or port the stock LT1 castings and throw in something like a 2.055" valve.

Do you think it would be better to get a port from eportworks.com on LT4 heads or the stock heads? I'd really like doign it on the stockers, then I wouldn't have to buy those LT4s just to have them polished and worked.

Never heard of eportworks...

The LT4 castings are serious toys. Those suckers can be made to outflow any LT1 casting. I hate hearing it myself but it all depends on what you what to do. Some guys spend thousands on fully CNC ported & polished AFR heads with 2.08" or 2.10" valves just to turn them right over to a performance shop and take off even more material, put in better valves, etc... How much HP do you want to make?

You're obviously paying less by working on stock LT1 castings. Your basic budget setup is porting them out and going with a 2.00" valve - the stock LT1 valve seats can be made to accept that size. Anything bigger and the seats have to be replaced and additional porting around the pockets has to happen. I think most shops get about 260 cfm between .500-.550 lift from ported LT1 castings with a 2.00" valve (depends on valve job).

I saw places years ago that offered this type of work for under $1500 USD (CNC job), plus extra stuff like a cam or something. Would probably be a lot cheaper now. Figure it out - how much would complete LT4 castings cost you, then add in just a port and valve job on the existing/stock 2.00" valves (those sodium filled intake valves are actually pretty decent, and lighter than stock LT1).

One thing thats becoming more popular these days are guys taking the LS1 style valvetrain components and using them on the LT1/4 Gen II heads (bee-hive springs, lightweight retainers, etc...) You bolt up a set of heads that flow 280, 290+ cfm with an ultalight valvetrain on top and that engine will be able to accelerate to 7000 RPM in no time.


Some guys live by cubic inches or big cams, and others swear by hi flowing heads. Its volumetric efficiency that the latter guys are talking about. Fact is by increasing the stroke you decrease the RPM acceleration of the engine. I personally think a stroker project is a waste if you plan on using stock heads - you'll have a big bad motor making loads of torque that will be completely starved for air at the top end. You hear about guys like that putting up big numbers on a dyno and then running slow ass times at the track.

Do the heads first, then drop in the crank.

cubes are nice, but i guess im one of those efficiency guys, ive always felt power was made by the cam and the heads, extra cubes are just an easy way to put more air and fuel in the engine. so ill agree with DVS LT1 that you should do the heads and cam first, and then do the stroker.

Sure does make sense, and based on all my reading, I'm with you guys, flow as much air as you can. Infact.... well I wouldn't say I'm against cubes, but I'm neutral. The reason I want the 383 is because you get some cubes and can also go forged.

None of us are against a stroker project - thats the ultimate route! You'll just get so much more out of it with the right heads, and cam too.

A lot of guys like dropping in big cams to make power through gross inefficiency (unless you're talking all out race cars with like .700+ lift solid rollers). I know a place that makes custom grinds that are basically .580-.590 lift with a 220ish duration, sometimes even as low as 218 duration, and these cams suite the LT1/4 motors so well - they make loads of power and are unbeliavably streetable because they are so efficient. Guys pass emmissions tests no problem.

Imagine doing up a set of heads, choosing the right cam, and putting together not just any cheap $800 stroker kit but investing in a really strong and lightweigh rotating assembly... it wont be cheap, but think about it.

Compare the car thats got the cheap stroker kit with the 50+lb forged crank and big .650 lift hydraulic cam - stock heads.

Now look at the car thats got the 38lb forged crank, .580 lift short duration cam, and ordinary ported & polished heads.

Even if those cars put up similar numbers on a dyno the second one is going to be totally streetable, burn a lot less gas, and likely run circles around the first car on the street (and be a hell of a lot smoother in the process).

Its going to cost more, no doubt. But its going to be a much more complete package for a street car. Daily driving will be a breeze.

^ That's what I was looking for. Now by smoother, do you mean all around or what? Because if I can do it without getting horrendus MPG I'd like a good deal of lope.

At least more then average.

On a side note, this thread isn't so much 383 vs. lt4 anymore, it's more of a 383 + lt4 thread. I don't want to do just one or the other, and I obviously want to make the best choices.

I know what you mean about a nice lumpy idle - something that turns heads at a stop light. I've got the hotcam right now and it shakes the bloody car - most people sitting inside think its going to stall or something lol.

You'd still get that with the type of cams I described - but it would be nothing like a gurgling, fuel spitting, about to konk out monster cam. Most of those big duration cams won't even operate power brakes without a booster (manifold vacum gets too low). Plus unless you're launching at over 4000 RPM you'll have no low end whatsoever.

Check out magazines like GM high tech and Hot Rod, they've always got great articles about making HP and HP theories. Will give you a better idea of what you should aim for.

so you think a 350 with a nice rotating assembly(forged), decent cam, and good heads(stock ported?) would outperform a 383 with about the same money into it? im liking this idea. my engine needs rebuild, so i may convince my parents that "the ported heads and shiney rotating assembly are way more fuel efficient than stock" :iceslolan

so you think a 350... would outperform a 383 with about the same money into it?

No way - same heads, same cam, but just the larger/heavier rotating assembly - the stroker will murder the 350. The smaller engine might accelerate faster than the stroker engine (getting it into its sweet powerband sooner), but the overall TQ & HP advantage of the stroker will make it mean peanuts. I feel like my babbling is just causing confussion now. My original point was simply to say you can get solid HP from a stock shortblock with a good head & cam combination just like you can from doing a stroker rebuild. Difference though will be the 350 is doing it more efficiently, but put that type of refinement into the stroker and its another story. Remember that so much power is determined by the heads.

Dude these are just different philosophies of power we're comparing, and there is no right or wrong. Some guys will go out and rebuild a 355 with forged rods, crank, and pistons because they want to do 10's or 11's with an engine that's designed to go 7000 RPM and has got disgusting heads with maybe a 250hp shot of nitrous or a blower. The guy next store may want to achieve the same performance with a 396 or 401 stroker that only operates between 4000-6000 RPM all the way down the track. It all depends on ideology.

I don't see too many people dumping a lot of money into an LT1 to rebuild it as a 350, unless they're planning some crazy and their point is to prove its being acheived by a 350. But take all that crap they've done and just think if it were a 396... It comes back to how much hp you want and how you want to achieve it.

ohhh, ok. thanks for clarifying.

so stroker = more power potential but smaller powerband

and 350/355 = more efficient, revs quicker/higher?

i want something that is fast, but still streetable(ie: not 8mpg lol) so i believe when the time comes, a forged 355 will be for me.

LOL - I hate you trying to paraphrase me!

The cam has more to do with an engine's powerband than probably anything else.

Often stroker motors are tuned not to rev too high simply because they are low end torque monsters, and also because the longer stroke means each revolution cycle is longer. But having said that, you look at the guys making the real power and all those stroker motors are getting peak HP between 6000-7000 RPM (those are the guys with the big heads and cam). A straight up 383 LT1 engine rebuild with stock heads would just be making noise after 5000 RPM more than anything.

Figure out how much HP you plan to make before rebuilding your LT1 into a 355 - bore it over, raise the compression and get new rods maybe, but you really don't need to change the crank unless you intend to make in upwards of 450 HP at the flywheel (even then you're still probably fine). There's a cop up here I know with a Grand Sport whose making 125 MPH passes in the quarter with an over .040 LT4, ported & polished heads, and an under .540 lift hydraulic cam. Granted the LT4 crank was desiged a bit stronger than the LT1 assembly, its still no forged 4340 unit - and most guys can't believe the car is making that kind of power with a stock crank.

To awesome. So as of right now I'm thinking stock bottom end with heads and intake? Ideas? That should make it easy to do a 383 later on, right?

thanks... lol sorry about paraphrasing, i gotta lay things out in stupid people terms for me to understand :lol2:

i'd like to eventually get mid 12's all motor, street radials, and a few bolt ons for the rear suspension. these are all plans probably way in the future. so dont bother with me now. lol. just taking in knowledge for the time being.

back on topic... :cwm27:

so you think a 350 with a nice rotating assembly(forged), decent cam, and good heads(stock ported?) would outperform a 383 with about the same money into it? im liking this idea. my engine needs rebuild, so i may convince my parents that "the ported heads and shiney rotating assembly are way more fuel efficient than stock" :iceslolan


from the same starting point, the 350 with improoved rotating assembly, cam and heads will outperform the 383 no question.

I just wish we could really bore out these damn motors like they're doing with the newer sleeved blocks. 427cid small blocks... who would have though back in the 60's?

they have 454cid small blocks........ not LS1 based, good old fasioned Small Block Chevys, that are 454 cid. they have had em since the 70's.

Thats nuts - what the heck is the bore x stroke of a 454 small block?? It's shit that the Gen II blocks can't (or shouldn't) be bored out any more that .060 over.

You gotta figure the big block would make more power though? I don't think a small block head could be made to flow 600 cfm, eh?

you need either a bowtie block or a 400 block to do it. I think its a 4.155 bore and something like a 4.25in stroke. Id have to do some research to find out exactly what it is.

i thought you couldnt bore a small block out to like 400ci! so a big block just has bigger pistons at the point or just more block?

there are two small block chevys, the 350 block, and the 400 block. the 400 comes from the factory with a 4.125in bore and a 3.75in stroke. but is externally the same as a 350 block with a 4.00in bore and a 3.48in stroke. there are other differences two but i wont go into that.

Big blocks are just that, bigger, much bigger both externally and internally. unlike mopar which uses the same sized block for both small and big displacement engines.

i could go for a nice 400! its a beautiful number. :)

it is, im surprised more guys dont swap the 400s into third gens, other than the torque factor. the unibody is weak and the 400 is a torque happy monster so maybe thats why.

mmmmmm torque, the other white meat!

Hahaha. Thanks, I think.

So does anyone have any advice or ideas?
Be different...go Lt5