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> Decisions, cant decide on a motor
Stang Killer
post Nov 20 2006, 12:17 AM
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So since my motor let go in late september (titanium retainer failed on me dropping a valve...you know what comes after that) Ive been slowly taking it apart in my spare time, slowly becuase I have no clue whats going back in there. Theres a couple combos thats come across my mind latley, each has its advantages, but not sure what to go for. This is an LS1 BTW.

1. Budget 346 (3.905b x 3.622s)
LS1 block
Stock crank
Stock rods
Forged pistons

Easy to get the ball rolling on seeing as I already have 2 sets of stock rods, 2 stock cranks, and 2 blocks. I would upgrade the rods with ARP bolts and have nice forged pistons with flycuts. Cam selection would be easy because theres so many off the shelf 346 cams that work.

2. Built 346 (3.905b x 3.622s)
LS1 block
Stock crank
H-beam rods
Forged pistons

Again, easy to get the ball rolling on as the only other major parts I would need are pistons and rods. Cam selection would be the same, and with this bottom end id also consider going solid roller. That is if I think ill take the time out for valve lash adjustments. Only down side is thoes that have gone solid roller have told me that its not too much fun on the street with stock cubes because of no low end.

3. Stroked 374 (3.905b x 3.900s)
LS1 block
3.90 crank
H-beam rods
Forged pistons

This is the biggest storke im willing to go with on the stock LS1 block because I don't like the idea of under-square motors. Id gain a good bit of CI in the process and I would be more likely to go solid roller with this combo becasue of that. Id also get more compression with this set-up without having to mill the heads as much. The only down side is there are no off the shelf cams for this motor.

4. Big bore 387 (4.125b x 3.622s)
LS7 block
LS1 crank
H-beam rods
Forged pistons

This is assuming the price on the LS7 block comes down like GM said. I wouldnt have to wait around for the block to get sleeved. A bore this size would allow me to run the LS7 heads, but I would go with a hyd cam because the only aftermarket rockers available for these heads are Jessel and thoes run 1300 bucks...no thanks.

5. Huge bore 398 (4.185b x 3.622s)
Sleeved LS1 block
LS1 crank
Forged pistons

This is the motor ive talked to my builder about, he seems just as excited about building this bad boy as I am. Again with this motor id be allowed to run LS7 heads, but then becuase of the bore id have to get a custom piston, and I belive a head gasket. This would also be a hyd cammed motor. The down side to this motor is that the cost of the shortblock alone is in the 5k dollar range. Looking at this motor on paper knowing that LS7 heads are capable of 380+cfm 600rwhp is an attainable goal, but that calls for a 12 bolt. While this motor does sound fun, it would be a handfull on the road course, and I would feel safe pushing it without a rollbar.

All of the motors would have fairly high compression 11.8-12.0 and the goal would be to make as much possible hp on less that 400 cubes because it seems that everyone is running a 402/408/427 ls1 these days. The car wouldnt be daily driven, and im not looking to change rear gears. Redline on all the motos would be around 7k, but 6500 max on the road course. It would also use an accusump for safteys sake. Ive considered building a motor around an LS2 block, but theres some minor things betwene the knock sensors for the LS2 and the computer of the LS1 that I don't really feel like getting into right now. So, if you have any input on any of these combos, let me know your thoughts.
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prockbp
post Nov 20 2006, 11:33 PM
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i would go with choice number 2... but, i'm poor and the only way i would ever do this mod is if i had no other choice..

i have no idea what i would choose if money was not a factor
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Rob Hood
post Nov 22 2006, 12:54 AM
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Do you campaign the car in a certain category/classification? If so, see what's allowed for engine upgrades and go from there. You may want to research some of the popular categories (SM for example) to see how far you want to go.

Build for torque, not HP - heavy cars need excellent mid-range power. No sense waiting on the engine to get into the upper RPMs for power when you're on track.
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BumpaD_Z28
post Nov 22 2006, 01:23 AM
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Displacement = (IMG:http://www.frrax.com/rrforum/style_emoticons/default/smile.gif)

build as "big" as you can afford but remeber that the power with come with "wise" heads and cam selection....
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Stang Killer
post Nov 22 2006, 02:13 AM
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I plan to go the HPDE--->Time Trial--->eventually AIX car because as the car sat before it blew it made 400/395 to the wheels and being at 3400lbs it was no way I could go AI even at full weight. Im sorta iffy on building a motor that ozzes tq simply because im not looking to break the 10 bolt. Im not really worried about the head and cam selection just yet. Ill deal with that once the bottom end gets in the car. If I end up with a 3.90 bore then ill go with the trickflows, If I go with a 4.0 bore then ill run the GM L-92 heads (330cfm stock), then if I go 4.1 or bigger ill run the GM LS7 head(360cfm stock).
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rmackintosh
post Nov 22 2006, 02:35 AM
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Build as MUCH AS YOU CAN AFFORD and then some......make it uncomfortable to spend that much.....I am not saying break the bank, as one should NEVER do that on a hobby, but stretch as far as you can....I say that as one who has gone the "budget" route a THOUSAND times, and EVERY time I do this it cost 4 times more as I have to chuck 90% of what I just did when I upgrade the next time....
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tom97ss
post Nov 22 2006, 08:56 PM
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QUOTE (rmackintosh @ Nov 21 2006, 07:35 PM) *
Build as MUCH AS YOU CAN AFFORD and then some......make it uncomfortable to spend that much.....I am not saying break the bank, as one should NEVER do that on a hobby, but stretch as far as you can....I say that as one who has gone the "budget" route a THOUSAND times, and EVERY time I do this it cost 4 times more as I have to chuck 90% of what I just did when I upgrade the next time....


Yup what he said
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Eugenio_SS
post Nov 25 2006, 07:41 AM
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i'd go for a stroker only, sinc you putting new pistons, might as well get a stroker crank.
Having said that... why not consider ls2 ?
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Stang Killer
post Nov 26 2006, 05:25 AM
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I don't want to deal with the LS2 because its no accurate way to read knock on the LS2 block using the LS1 PCM. Even tho its harnesses and everything else to use them, most shops just disable them all together. Id rather keep mine and know that theyre accurate. Only thing that would change my mind on it is if I ran an LS7 block, and thats only if the price falls.

Over the last couple days thinking about what ive been told here, im 100% positive that I wont be using a 346 in the new build, and the only way im staying with the stock crank is if I go with one of the bigger bore blocks.

This post has been edited by Stang Killer: Nov 26 2006, 05:25 AM
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