JZ'sTA

iTrader: (23)

Car is going 90% race car.
100+ octane will be used.
250+ DP NOS Setup will be used.
Here are the 2 choices.
1. 370 cubic inch 6.0
Bore to 4.030, with 1000 dollars rods, JE coated pistons, stock crank.
Cam is a T rex (remember this is a nitrous car)
Heads are for either the 370 or 408 and are a stage 3 LS6 head flowing over 330@600 lift. 56cc's.
FLP stage 5 with a 3800 Yank Nitrous converter.
Compression will be 12.3:1

OR SAME SETUP WITH A 408.
The only difference is the 4" stroke.
Again good rods, and pistons. Cam is a 242/246 598/605 114 LSA (Better for the nitrous over the t-Rex)
Compression will be 13.5:1

The 408 will cost 2000 more which is the cost of the crankshaft.
Both motor's are slightly used and therefore I know both work well.
Will the 408 be worth the extra 2000 dollars?
I feel it will be as I get a stronger bottomend, over a full point of compression which I am using race fuel, a better Nitrous cam, more torque, and it should handle a big shot easier with the extra cubes.
Plus I believe it will idle better and for the rare use on the street run better.

So what do you guys think?
Worth 2000 dollars?

black_knight

iTrader: (1)

Yes. No reason not to go bigger in this case.

DONAIMIAN

iTrader: (18)

I say yes. With it being 90% race car, get every last cube you can.

Ferocity02

iTrader: (60)

This is a tough descision. I'd say go with the 370 due to the shorter stroke, which will be good for a race car that constantly sees HIGH RPM's. However, depending on how much power you are looking to get, I am weary of the stock crank, even though they are known to hold 1000+ crank horsepower. Also with the 370 you save money for the other things that you will need. Perhaps you can swap out the stock crank for an Eagle 3.622" stroke crank, which is defintely stronger than stock.

SDB

iTrader: (7)

go with 408 and make sure the heads have 2.08 or 2.10 intake valves....otherwise you may want to stay with 2.055 intake on the 370 cube....

black_knight

iTrader: (1)

Ferocity makes a good point; don't get a cheapie crank for the 408. If you're confident that you have a quality piece that will hold the power you want, then do it.

JZ'sTA

iTrader: (23)

Launti crank is what is in the 408.
Also a good point was made.
The valves are a 2.055 and are LPE/TEA heads. LPE did the port work, TEA just redid the valve job, some hand blending, and a few other tricks.
Flowed them on a 4.030 bore and we were all impressed.
Brian (from TEA) felt the 2.055 valve was better for the head after he had a chance to see it. Before he had it in his hands we were going with a 2.08 valve.

As far as saving money.... I have every last piece already bought and maybe even some extra stuff. I want to do this once and do it right.
Fuel system, massive suspension, stage 5 trans, converter, 12 bolt, slicks and skinnys, etc are already purchased and either in the car or at the house.

Order 66

I say go for the 370. Only difference you see between the two motors is the low end on the 408. The 408 will have a better cross the board numbers. The 370 will be able to rev higher. And since this is a drag car you will launch high and wont see low rpms. I am a short stroke bigger bore fan.

JZ'sTA

iTrader: (23)

Can one of you cam guru's give me some numbers on static compression and DCR?
Tell me which combo looks better from that stand point.
.040 gasket being used, 56cc head, -.005 piston height.
Also I plann on shifting around 7000 RPMs as this combo has to stay together for a while because breaking something sucks but having cash to fix it sucks even more.

JZ'sTA

iTrader: (23)

I am a short stroke bigger bore fan normally myself. I am not running a huge verter b/c of the Nitrous but I doubt I will see RPM's under 5800 through any race. I know the 408 will be much faster off the nitrous and be more fun to drive if spinning your tires is fun.....
I am surprised noone has said anything about the cam difference yet.
Many like the 114 LSA for juice.
Its not like I cant swap out cams though.....

vtanju

iTrader: (2)

i would go with the 408 using the 114 cam and 13.5CR with race gas. very good combo.

CMSDave

What crank is it that it's $2000 more than a stock crank?

strokedls1

iTrader: (1)

I would do the 408. People are tripping on reving the 4" stroke. I have a 4.075 stroke lunati that can be spun as fast as the valve train can handle. Been to 7200 rpm quite a few times on a hydrallic cam. The 408 will give you a hell of a lot more than just low end torque. You have the weight penalty either way so why not get more cubes out of it.

black_knight

iTrader: (1)

Even if you don't spin the 408 as high as the 370 it can still make more power, potentially. You can always swap the cam, and I would recommend a custom cam if you're of the "do it once" school, as you say. I won't comment on the durability of this or that brand of crank, but if you get a really good one, there is no reason not to go with the bigger one for this sort of application.

And I especially think that's a good idea for you, since you want to "do it once." If you go with the smaller cubes, you might end up wanting to do it again... with the larger cubes you can be more sure you won't have to.

383LQ4SS

iTrader: (33)

I say 370. With the proper setup and the proper NITROUS Setup...I am confidant you could make whatever power you are looking for. I belive 850 rwhp could be done. If you want more than that...I would think about the 408. I had the 385 ci motor (which Jeremy has the parts in hand now for you) and it made 522 rwhp all motor and I was planning on a 350 shot or so for a total of ~850.

And the best part....if it ***** the bed...you arent out a $2000 crank. And it has a decent chance of shitting the bed at some point if you are planning on seriously pushing it.

What are your HP goals anyways?

ChucksZ06

iTrader: (9)

I would go with the 370 because of the large nos shot. The amount of nos and how well you are going to distribute it to the cylinders is going to have a lot more to do with how much power you produce. Why would you want more low end in a race car? People always talk about low end on this forum...low end is for trucks and those who have broken arms and can not shift... In all seriousness though I think you will have a quicker revving engine and save money. I would also recomend the 370 if you were going FI. Good luck.

JZ'sTA

iTrader: (23)

Wow a back and forth post. Thanks so far for the replys.
Also thanks for not posting the "there's no replacement for displacement" saying.
The crank is a Launti.
I own both motor's already and this setup is going in my "might as well be brothers" car.
The price difference of 2000 is a guess as to what I can sell the other motor for and the difference there will be. I was guessing 3000 for the 370 and 5000 for the 408 with the better launti crank.

JZ'sTA

iTrader: (23)

I am somewhat surprised by your reply and mainly because you made the bigger cubic inch choice while being in nearly the exact same position. You went from a 385 (same as the 370 but a offset crank and 4.060 bore) to a 415 (same as a 408 but again with a 4.060 bore)
You are also converting to the more race side and running a big shot of nitrous. Your name acturally came up as a example when talking about the swap. So why did you go bigger AL?

Also HP goals aren't as important, would like to run bottom 9's in about 6 months-1 year after everything is dialed in, adjustments have been made, and a bunch of race time has been invested. A 250 shot is DEFENTIALLY NOT the limit just a good place to start. Bottom 9's is a goal that I believe is reachable with a lot of work. Would like to say 8's but that sometimes is harder to achieve then any of us can think.

PS.....Thanks for the pistons and rods.
I recieved them the same day you gave them to Jeremy as he was on his way down that day.l

Elite_Hot_Rod

if you intend on throwing a 250 shot at it I would suggest using ARP 1/2" head studs and SCE Titan head gaskets or chances are you'll blow the gaskets or push water with the compression ratio that high. You never mentioned what type of intake manifold you are using and what the fuel system will be, 2 very important factors. Also I don't think a 4L60E will handle that kind of power and a 3800 RPM stall will probably be to tight for that sized shot also. Been there, done that.

JZ'sTA

iTrader: (23)

All very good points.
I have a T-400, t/Brake, cheeta shifter, converter, + everything to make it work siting on the shelf waiting for the 4L60E to blow up.
ARP head studs are here, and cosmetic gaskets are being used.
90mm Intake, with a very expensive DP Nitrous setup plumed and ready to roll.
Fuel system is a custom fuel system we pulled out of my old 408 Twin Turbo setup so fuel should be no problem.
Basicially it is a sump tank with dual Huge ( dont remember what size) fuel pumps.
We were going to run a seperate tank but decited just to run race fual all the time.
What size verter would you suggest?