370 vs. 408...which one and why?
04-26-2008, 02:43 PM
#1
370 vs. 408...which one and why? Given that there is less than a $1,000 difference between a 408 and a 370, is there any reason not to go with a 408? I was looking at one set up with Callies rods/crank and -15cc Diamond pistons. Heads would be stock 317s. How much boost would something like this handle and what kind of power are we talking about (D1SC)?
All feedback is welcomed.
All feedback is welcomed.
04-26-2008, 02:58 PM
#2
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im going to say the 370 because i like large bores and smaller swing and then boost the hell out of if and spin it high but its all in what you want to do with the car
04-26-2008, 05:40 PM
#3
370 might rev a touch faster and maybe you could wind it a bit higher.
408 will make more torque on and off boost and would think more hp at same boost as the 370 and spool up turbos quicker as well. Its pretty much a win win but does cost more money of course. Lots of 370 guys run the stock crank to high hp levels. I do feel a bit safer though with complete forged engine.
408 will make more torque on and off boost and would think more hp at same boost as the 370 and spool up turbos quicker as well. Its pretty much a win win but does cost more money of course. Lots of 370 guys run the stock crank to high hp levels. I do feel a bit safer though with complete forged engine.
04-26-2008, 06:02 PM
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Given that there is less than a $1,000 difference between a 408 and a 370, is there any reason not to go with a 408? I was looking at one set up with Callies rods/crank and -15cc Diamond pistons. Heads would be stock 317s. How much boost would something like this handle and what kind of power are we talking about (D1SC)?
All feedback is welcomed.
All feedback is welcomed.
Im building a 408 with -15cc pistons for my 99 Corvette as we speak....I will be using a D1SC and probably a 3.6 pulley on the blower since I decided to use a 8" crank pulley! ! Im hoping 15 Lbs. of boost! ! The cam is a 23X/24X on a 114! !
04-26-2008, 06:16 PM
#6
do the 370 and use the money elsewhere like the power adder
. You can make 700-900rwhp with the 370 no prob. Sometimes its better not to go overkill on some stuff because the outcome wont be worth the extra couple horsepower compared to the THOUSANDS you have to spend to get a 408 up and running on boost. Larger turbo, larger wastegate, bigger pipes, better heads/intake to take advantage of the 408...etc etc...**** for that just do a stock 346 built up and run 16psi =) You'll make BIG power with whatever motor combo you choose, just decide how much money you want to spend...thats ALWAYS the limiting factor
. You can make 700-900rwhp with the 370 no prob. Sometimes its better not to go overkill on some stuff because the outcome wont be worth the extra couple horsepower compared to the THOUSANDS you have to spend to get a 408 up and running on boost. Larger turbo, larger wastegate, bigger pipes, better heads/intake to take advantage of the 408...etc etc...**** for that just do a stock 346 built up and run 16psi =) You'll make BIG power with whatever motor combo you choose, just decide how much money you want to spend...thats ALWAYS the limiting factor 
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04-26-2008, 11:01 PM
#11
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they do and its less strain on the pistons sides with a smaller stoke also if you have small turbos we all know that to much backpresure is not a good thing
the 408 is bigger so the rest of the set up will have to be bigger to keep up and the cost of all that adds up its all about what you are trying to do i keep saying this
the 408 is bigger so the rest of the set up will have to be bigger to keep up and the cost of all that adds up its all about what you are trying to do i keep saying this
04-27-2008, 12:49 AM
#12
have heard turbos like short stroke. 370 gets my vote.
When the boosted list was up you could see there were tons of 408 and 402s running fantastic times. Not sure what happened to it. It was handy to compare mods.
One reason I went to 408 is wanted to go fully forged crank .As said off boost the bigger motor is superior and it should spool turbos quicker be they smaller ones or bigger ones. And if you can use less boost to make same power that might be easier on head gaskets too. And optimum turbo sizing depends on your goals.
Does a guy need more than 1000 engine hp? Can a person hook up more than 1000 hp in a street car, in fact most cars like ours? Pretty much need wheel tubs and giant tires,etc to hook up much past 1000. And of course you need medicals ,full cages etc to run under 10s at most NHRA tracks. So personally think much past 1000 is overkill. Rather set things up at maybe 600 rwhp. Have smaller quick spooling turbos. Have a wider powerband and have bigger motor for better off boost torque and hp. And just feel better with fully forged motor but stock 370 cranks have done think 1000 at least with not much trouble.
Is the 408 worth the extra 1000 or so on a FI motor. Depends...
Is it worth it NA ..no question..Unless you are looking for better mileage or something. That said it was a big jump it seemed to go to 427 or 454. So did stop at 408.
04-27-2008, 08:22 AM
#13
Bigger is always better. If the money isn't a concern, go 408. Money is THE only reason to not go bigger.
There will be guys who will tell you that so and so went x.xx at xxx mph on 346, etc. The fastest cars on this forum use bigger motors.
If you have an idea of what the final power goal is, its easier to suggest what to use. For example, if you want "only" 700 RWHP, a 346 can get that done. If you're looking to make 4 digit power, get all the cubes you can.
There will be guys who will tell you that so and so went x.xx at xxx mph on 346, etc. The fastest cars on this forum use bigger motors.
If you have an idea of what the final power goal is, its easier to suggest what to use. For example, if you want "only" 700 RWHP, a 346 can get that done. If you're looking to make 4 digit power, get all the cubes you can.
04-27-2008, 08:37 AM
#14
Wow some misconception in this thread, I believe the combo as a whole has to work together. In FI bigger is not always better, especially turbo you have to watch out for backpressure. Not only that but a 370 is better for boost, shorter stroke and rev it higher, etc. Put it this way, I have my fully forged 408 built and decided to rip it apart and order a callies dragonslayer 3.622 crank. I believe the net power will be about the same but will work allot better with allot less issues, etc. Again though, think of the build as a whole. If you will run a D1 or a t76, than 370 it is and don't look back. The 408 will need to upgrade allot of other things as well as the power adder like the exhaust and or downpipe which could lead to having to get an aftermarket K member, etc. Keep it simple, a 370 can make allot of power and depending on your goals it may make more than you need. 1000 hp no problem setup right and yes cheaper too. Stock cranks are proven even though I stepped up to a forged crank but the price was right
04-27-2008, 10:46 AM
#16
408 
