370 OR 408 for boost?
05-31-2009, 05:23 PM
#1
370 OR 408 for boost? For a turbo car, which would be the better shortblock to go with? They both obviously will use the same block but different cranks. I am going to be putting together a shortblock to use in a turbo setup and will probably be using a 76 for the turbo. I am looking to make around 750 or so, maybe up near 800 in the future but for right now I'd be happy with right around 750, give or take. The 370 will be cheaper and I could use that money to go towards the turbo setup and just turn the boost up a little, I am assuming they will both be able to handle 800RWHP so that won't be an issue. Just wondering for all intents and purposes which one I should be using.
Thanks
Thanks
05-31-2009, 05:49 PM
#2
Biggest you can afford. Stock cranks are strong. Forged cranks are stronger.
Bigger engine will give faster spool up. Bigger engine will have more power and torque off boost which is likely a lot of the time where you will be at. You can't go into much boost around town, at least not in my city!
More power you start with less boost you need to run. My built 408 is very powerful off boost . Just tap a few psi and its moving real good. Tap a lot of psi and its starship enterprise time!
Again its buget mostly.I would have liked a 427 although it would be even more overkill .Maybe next time around.I had a budget and the 427 was a bit past it. And in hindsight no real regrets. Car is traction limited not power limited. And thats a nice place to be!
Rember a turbo has max hp potential. say 1000 engine hp. It will just hit that at lower boost on the bigger engine. But area under the curve will of course be much better on the bigger motor and it will as said spool the turbo faster. My 2.4 in my talon spools the turbo faster than a 2.0.
And I also believe in reasonable compression on a mostly street motor. 9 to 1 or 9.5 to 1 if you are going to run alc/meth. 8.5 is for track cars in my opinion. I like as said a snappy car off boost. Warn you with a built 408 plan on buying a lot of tires.
Bigger engine will give faster spool up. Bigger engine will have more power and torque off boost which is likely a lot of the time where you will be at. You can't go into much boost around town, at least not in my city!
More power you start with less boost you need to run. My built 408 is very powerful off boost . Just tap a few psi and its moving real good. Tap a lot of psi and its starship enterprise time!
Again its buget mostly.I would have liked a 427 although it would be even more overkill .Maybe next time around.I had a budget and the 427 was a bit past it. And in hindsight no real regrets. Car is traction limited not power limited. And thats a nice place to be!
Rember a turbo has max hp potential. say 1000 engine hp. It will just hit that at lower boost on the bigger engine. But area under the curve will of course be much better on the bigger motor and it will as said spool the turbo faster. My 2.4 in my talon spools the turbo faster than a 2.0.
And I also believe in reasonable compression on a mostly street motor. 9 to 1 or 9.5 to 1 if you are going to run alc/meth. 8.5 is for track cars in my opinion. I like as said a snappy car off boost. Warn you with a built 408 plan on buying a lot of tires.
05-31-2009, 07:12 PM
#3
all of the above is correct. But for my choice I chose to go with a 365ci stock crank, bc it is plenty to make more that what your goals are. With what you save on the crank you can get yourself quality parts heads, a head unit, headers/exhaust, and a good intercooler and you can make 800rwhp + with pump gas.
You can do it either way its all on budget. You can do a search is been talked about lots.
cant go wrong with any FI LSx , good luck
You can do it either way its all on budget. You can do a search is been talked about lots.
cant go wrong with any FI LSx , good luck
05-31-2009, 08:04 PM
#4
all of the above is correct. But for my choice I chose to go with a 365ci stock crank, bc it is plenty to make more that what your goals are. With what you save on the crank you can get yourself quality parts heads, a head unit, headers/exhaust, and a good intercooler and you can make 800rwhp + with pump gas.
You can do it either way its all on budget. You can do a search is been talked about lots.
cant go wrong with any FI LSx , good luck
You can do it either way its all on budget. You can do a search is been talked about lots.
cant go wrong with any FI LSx , good luck
05-31-2009, 08:22 PM
#5
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go 370 and spend the saved money on good heads!
stock cranks are being pushed to over 1000 hp!
and if everything is in order like main studs, propperly balanced, a good tune, and proper fuel i see no problem with a stock crank.
but heads are where you should be worried. you DO NOT want to lift a head!
stock cranks are being pushed to over 1000 hp!
and if everything is in order like main studs, propperly balanced, a good tune, and proper fuel i see no problem with a stock crank.but heads are where you should be worried. you DO NOT want to lift a head!
05-31-2009, 09:35 PM
#7
http://texas-speed.com/shop/item.asp
That will give you a baseline. Figure a good $2500 for a GOOD set of heads also. top it with an intake and some ARP fasteners, and you are looking at close to $10K pretty fast.
you have to ask yourself "how fast do I want to go?" which in my case is " how much money do I have? "
don't expect to build a car for cheap and have it be fast. Don't build a fast car, and expect it to be cheap.
That will give you a baseline. Figure a good $2500 for a GOOD set of heads also. top it with an intake and some ARP fasteners, and you are looking at close to $10K pretty fast.
you have to ask yourself "how fast do I want to go?" which in my case is " how much money do I have? "
don't expect to build a car for cheap and have it be fast. Don't build a fast car, and expect it to be cheap.
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05-31-2009, 10:04 PM
#8
For a turbo car, which would be the better shortblock to go with? They both obviously will use the same block but different cranks. I am going to be putting together a shortblock to use in a turbo setup and will probably be using a 76 for the turbo. I am looking to make around 750 or so, maybe up near 800 in the future but for right now I'd be happy with right around 750, give or take. The 370 will be cheaper and I could use that money to go towards the turbo setup and just turn the boost up a little, I am assuming they will both be able to handle 800RWHP so that won't be an issue. Just wondering for all intents and purposes which one I should be using.
Thanks
Thanks
Or scan the details of some of Epp's ATI builds -and maybe a turbo or two, but again nothing exotic for the motor needed to make 750 rwhp. The additional expense will be all of the extras you need to add to your car to handle double the power such as: suspension, TC, transmission, drivetrain, cooling, fuel system, tuning, meth kit, wheels and tires, and so on adding up to an easy 10k or more.
Last edited by dlandsvZ28; 06-01-2009 at 06:31 PM.
06-01-2009, 06:17 PM
#9
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I bought a "boost" 370 from speedinc, wasn't that bad of a price with the extra stuff I added to it. They said it would handle 1k if I wanted to push it that far... I won't, but its nice to know I could
06-03-2009, 04:16 AM
#11
I went with a Speed Inc 370 as well. I figure I will have PLENTY of torque on hand already and with the procharger coming on in a more linear way with RPM I would have an easier time launching the car on the street. A big torquey motor, and boost on top of it = blowing off almost all but a full slick on the street. I like being able to actually use some of that power I am making, and races start from a standstill for me, so being able to get out of the hole without blowing the tires off is nice. Just my wacked out opinion.
06-03-2009, 05:45 PM
#15
at Texas Speed, their 370 shortblocks are cheaper than their 347's 
[by$100]. from TSP, here is how they stack up:
370:$3,000
408:$3,700
i use TSP b/c they have the most user friendly website, prices are easy to check. other sponsors are definately worth a look as well. for that 700 in savings you can buy what? a boost controller, etc. but you also get the extra torque & spool speed of 38 more cbues. that said, a 370ci motor wont spool slow lol. look around, weigh your options, and most importantly your wallet and see what fits you best!
[by$100]. from TSP, here is how they stack up:370:$3,000
408:$3,700
i use TSP b/c they have the most user friendly website, prices are easy to check. other sponsors are definately worth a look as well. for that 700 in savings you can buy what? a boost controller, etc. but you also get the extra torque & spool speed of 38 more cbues. that said, a 370ci motor wont spool slow lol. look around, weigh your options, and most importantly your wallet and see what fits you best!
06-03-2009, 08:30 PM
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I could have had my 346 made a little stronger and better and added a forged rotating assembly, but I decided that the iron 6L block and good internals with the stock crank for 3300 was WELL worth it. Plus, I would LOVE to try and get over 750rwhp with it... safely
12-09-2009, 11:10 AM
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Has anyone considered the fact that the piston's wrist pin on a 408 comes almost half way out of the bottom of the bore at BDC (in a 6.0L block)? I do not like that idea one bit...
I am also stuck between a 370 and 408, so I am subcribing...
I am also stuck between a 370 and 408, so I am subcribing...