355 or 383
09-02-2006, 04:18 PM
#1
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355 or 383 Hi guys, I am about to teare down my LT1, and I cannot decide on a 355 or 383. This is a terribly tough decision.... I dont know whether to just go with new pistons/rings and keep it a simple 355, or go all out with an entirely new rotating asembly... I need some insite here. I will be using AI's 180cc street/strip H/C, intake porting from AI, complete valvtrainnew 4L60E, and a stall, etc etc. This is my DD (except winters) and there are NO plans of nitrous/boost in the future. I am looking to hit the 400rwhp mark with as many sreet manners as possible. I am leaning more towards a 355, but my question is, will the stock crank/rods be ok?? It will get all new bearings/bolts etc etc as it should. It has 85k on it. thanks
09-02-2006, 04:24 PM
#3
Thing is to recondition the stock rods cost almost as much as some basic reliable Scat rods, a cast Scat crank is under $200 then you will need balancing. Bet 355 to basic 383 there is only a $500 difference not much considering it should last for a good long time.
Then again a stock shortblock can do the job without a rebuild in most cases. That is the route I took, one day I will do a stroker to put under the AI parts but for now the stock shortblock is doing fine.
Then again a stock shortblock can do the job without a rebuild in most cases. That is the route I took, one day I will do a stroker to put under the AI parts but for now the stock shortblock is doing fine.
09-02-2006, 04:37 PM
#4
heres the deal with the two
350/355 you will have good hp but it will occur at a higher rpm.
383/388 you will have about 15-20hp more i know it does not sound like much but the tq that the 383 puts out down low is definately worth that extra money..you cant go wrong either way there are some very strong 355s out there look at lt1ta from louisiana he is a 9 second n2o car with a cc306 and Le-3 heads,its all up to you
350/355 you will have good hp but it will occur at a higher rpm.
383/388 you will have about 15-20hp more i know it does not sound like much but the tq that the 383 puts out down low is definately worth that extra money..you cant go wrong either way there are some very strong 355s out there look at lt1ta from louisiana he is a 9 second n2o car with a cc306 and Le-3 heads,its all up to you
09-02-2006, 04:54 PM
#5
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I thought it was 377/383? when comparing it to 350/355.
why ya rebuilding it? How many miles are on the engine? A stock short block will support cars into the low 12's, and even faster.(at a caprice weight
) My dad gets to drive 3 LT1 cruiser's, at 220k, 200k, and 175k. they all still can smoke the tires.
I think chad golen does rod reconditioning for $130 a set(IIRC), but you could likely step uo to a stronger rod for not alot more. I thought stock rods were really good for clearance in a 383, but some others are aswell.
If your rebuilding it to be at maximum power, just skip it, and put the money in the heads. Unless you have a BIG trust in the shop, the engine could come back with less power that it had before.
Just throwing this info out. Anyways.
355: Will want to rev higher, won't have much low-end torque below 3000 rpms with a big cam(a stall will take care of that ), and it will have slightly better milage than a 383(in comparative setup)
383: More hp, will likely peak at a lower RPM, can support better flowing heads, can support a bigger cam, and will have more torque sooner. Which is a good thing if you ask me.
@nthony: a 355 is a .030 over bored 350. I don't think bigger rings would not take up that much slack.
why ya rebuilding it? How many miles are on the engine? A stock short block will support cars into the low 12's, and even faster.(at a caprice weight
) My dad gets to drive 3 LT1 cruiser's, at 220k, 200k, and 175k. they all still can smoke the tires. I think chad golen does rod reconditioning for $130 a set(IIRC), but you could likely step uo to a stronger rod for not alot more. I thought stock rods were really good for clearance in a 383, but some others are aswell.
If your rebuilding it to be at maximum power, just skip it, and put the money in the heads. Unless you have a BIG trust in the shop, the engine could come back with less power that it had before.
Just throwing this info out. Anyways.
355: Will want to rev higher, won't have much low-end torque below 3000 rpms with a big cam(a stall will take care of that
), and it will have slightly better milage than a 383(in comparative setup)383: More hp, will likely peak at a lower RPM, can support better flowing heads, can support a bigger cam, and will have more torque sooner. Which is a good thing if you ask me.
@nthony: a 355 is a .030 over bored 350. I don't think bigger rings would not take up that much slack.
09-02-2006, 04:57 PM
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96capricemgr, how do you like those heads from AI? I am getting the 180cc ones. I think Im just gonna go 355, and stick with the stock crank/rods... I dont want to have the more agressive top end to feed the 383. A cheaper, quicker reving 355 is what im ooking for I think. My only question is reliability.. Will everything be ok? (stock crank and rods) 
decisions..
decisions.. Trending Topics
09-02-2006, 06:03 PM
#11
I am loving the AI heads and cam, they did the intake as well. In awesome weather with the old mild cam only the car went 13.2, first problem free night out(first night the FP proved inadequate) it went 12.6 the only other changes were I went to a 3400 Edge from a 2800 and to bigger injectors to support the new power, that was with the same 3.42 gears and tires and such. Since we picked away at the tuning and I did 3.73s and in June it went 12.5, the worst day out since the swap was the end of July 90s and HUMID and it still went 12.9 and that was after driving it 150 miles to the track. Can't wait for some fall negative DA weather.
09-02-2006, 06:13 PM
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Caprice, do you think the 180cc's will feed a 355 ok? Im getting the intake ported by them as well... Do you know what "cc" these are, like 58 or 76 etc etc? i am needing to know this so I can choose pistons. thanks
09-02-2006, 06:41 PM
#13
They will be a big improvement over stock, a 355 topped with them will be nice.
Far as chamber volume the stock heads start at roughly 54cc, Phil will do some contour work in there which will make it larger then he can mill them to make it smaller again, those details you will have to workout with him. You will need to decide how much the block will be decked too so they can get the intake mating right. The 54cc number will get you in the ballpark though and then use decking the block milling the heads and gasket thickness to finetune compression.
Far as chamber volume the stock heads start at roughly 54cc, Phil will do some contour work in there which will make it larger then he can mill them to make it smaller again, those details you will have to workout with him. You will need to decide how much the block will be decked too so they can get the intake mating right. The 54cc number will get you in the ballpark though and then use decking the block milling the heads and gasket thickness to finetune compression.
09-03-2006, 12:48 AM
#14
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Caprice, Im not sure on what parts I should use.. I need some suggestions.. What compression would I be looking for? I want a well-mannered, reliable & 400rwhp thru an A4. Do you think the 190's would be better suited for a 355? I need advice on rotating assembly parts/brands. Can I do it without a crank and rods? Can reconditiond parts be reliable? sorry for all the Q's.. thanks
09-03-2006, 08:50 AM
#15
The stock crank is great, really so are the rods. Like I said though rod reconditioning will cost nearly as much as some lowend but reliable rods. Golen mentioned above does have some cheap reconditioned LT1 rods but I think those are for with engine builds.
Do you have to worry about emmisions?
Using the online MPH in the 1/4 to HP calculators I get a little over 400rwhp, have not been to the dyno yet though. We pushed compression on my stock shortblock to 11.5:1 the cam is similar duration to the Comp 503, but with clearly custom specs. It lopes decent at idle but still drives well enough to have the wife drive or tow my small fishing boat. I put over 5K miles on it since the heads and cam swap the end of April.
Do you have to worry about emmisions?
Using the online MPH in the 1/4 to HP calculators I get a little over 400rwhp, have not been to the dyno yet though. We pushed compression on my stock shortblock to 11.5:1 the cam is similar duration to the Comp 503, but with clearly custom specs. It lopes decent at idle but still drives well enough to have the wife drive or tow my small fishing boat. I put over 5K miles on it since the heads and cam swap the end of April.
09-03-2006, 02:58 PM
#17
You know to be honest I would talk to Phil and see what the heads were ported for. If they were setup for a 355 I would save the cash and go with a 355. I made well over 400RWHP on a stock Short block. With a good build and proper DCR you should have a great daily driver and be very happy.
Now if you are up to spend the extra cash for a full rotating Assy. and the work to put it in...AND if Phil ported the heads for a more Cubic Inch's go for the bigger engine
Now if you are up to spend the extra cash for a full rotating Assy. and the work to put it in...AND if Phil ported the heads for a more Cubic Inch's go for the bigger engine
09-03-2006, 03:30 PM
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Im jus goin with new pistons and all the little stuff. I think the heads will compliment it nice. Im looking for around a 230/236 and a 112 lsa. I may use the 306 or 503... Its whatever AI reccomends after they hear my plans... thanks for all the help
09-03-2006, 05:04 PM
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My last motor was a 355 LT1.... Stock crank, eagle 6" rods, and SRP forged pistons -5cc dish... ported LT1 heads/manifold, 58mm throttle body and all the requisite bolt ons... 236/242 .556/.576 112lsa hyd roller cam.... thing ran like an animal.... 11.62@119 on the motor, 10.40@131 on a small 150 shot.... 3550 lb registered/tagged streetcar....
I say if you have the cash go with the 383... a good crank is gonna cost you about 600-1200 depending on how much quality you're talking about in addition to the extra cost of clearancing needed by your engine builder... after that the power made is a toss up.. the 355 will make just as much HP but at a higher twist and the 383 will outtorque the 355.... But the 355 for less money is a very capable motor... i loved the damn thing.....
I say if you have the cash go with the 383... a good crank is gonna cost you about 600-1200 depending on how much quality you're talking about in addition to the extra cost of clearancing needed by your engine builder... after that the power made is a toss up.. the 355 will make just as much HP but at a higher twist and the 383 will outtorque the 355.... But the 355 for less money is a very capable motor... i loved the damn thing.....