ok guys, here is the problem:
I only have 2 choices for pistons: 10-1 or 12.5-1, from SRP. That's the only choice I could find (srp wiseco etc). Now, 10-1 with my 288AR (comp cam) will be kinda low on the cranking cr, but 12.5 would be just to much (for 93 octane). If I go one step higher for cam and use the 308AR, then 12.5 is right on the money for cranking cr (for 93 octane). But here is the compromise:

According to desktop dyno 2000:
the 288AR with 10-1 will have an average of 51ftlb of tq extra from 2000 to 4000 than with the 308AR and 12.5-1 .

at 4500rpm, the 308AR will make more torque all the way to its peak at 5000rpms, where the 288AR will peak at 4500.

Same with hp, anything below 4500 the 288AR makes more than the 308AR (about 20hp more average below 4500). After 4500 the 308AR will make more, up to 50hp at 6000rpm

what would be the best for the street? I'm thinking the 288AR and 10-1 cr. If I had to, I could get custom pistons to up the cr to about 11-11.5 which would move the curve upward for the 288AR cam and close the gap on top end power compared to the 308AR, still blowing the 308AR tq below 4500.

the 288AR peaks at 6k while the 308AR peak at 6.5k

it's going into my 69 camaro with a 2500 TCI stall, TH400 and 3.73 gears (with BFG DR) and full interiror.

I don't really want to spin the motor past 6k because it is a 2 bolts (I will be using ARP studs instead of bolts for the mains to help things out) I'm a tad scared that 10-1 isn't gonna be enough compression and I might be disapointed. Also it might be important to note that I'm using Canfield alum 310cc. I seriously doubt that even with alum heads, 12.5-1 with the 288 AR isn't gonna cut 93 octane (I did polished the chambers, and I would debur the pistons domes)

what do I do?


Choices are:
288AR with 10-1
308AR with 12.5
288AR with 12.5 (and pray alot)
288AR with 11-1 (custom pistons=more$)

I'm leaning towards 288AR with 10-1
Also got a cheater NOS system I could hook up for any lack of power

 

with that converter and those gears, go with the lower compression and smaller cam It'll be fun on the street with all that torque

 

Go with 10:1 pistons and pay the money to have your heads shaved a few cc, 12.5:1 seems a bit much if you have uncertainties about the bottom end of your motor. What are the specs on those two cams?

 

288AR is 244@50 with 602 lift at the valve (according to my timing card)

the 308AR is 264@50 and 636 at the valve (according to compcam web site)

both are on 110 lobe

288AR intake valve closes at 70 while the 308AR closes at 80

the 288AR would need 11.2-1 to give me an 8.5 DCR....the 308AR with 12.5 would give me 8.5 right on, but is loosing alot of torque below 4500

the 288 with 9.9-1 would give me in the 7.7 dcr...I had 9.7 with my 396 and that cam and was disapointed by the output (timing was in the mid 40 for optimum power..which would indicate not enough cr)

 

Nice cams. I would go with the 288 if you dont want to wind that BBC over 6k rpm. I wish you had a cam in the 25X @.050 range, but the 288 should be plenty big and still with plenty of torque.

 

like others said, I would get the lower compression piston and mill the heads.

 

there's one, the extrem energy 296 which checks in at 254 I belive....I'm more concerned about loosing alot of torque below 4500 with the more agressive ones...it's a street car...51lb lost on average below 4500 is alot...granted it's a computer software and it only gives ya an idea, but I'd say even if it came to 30ftlb in real life, that's still quite a bit for an average loss...with the 396, I it wasn't till I hit 5000 that it would really pull away and hard all the way to 7200 (it was a 4 bolts), and even though it was fun, always wished I had more low end to make things more fun ...so you guys know that 396 did a crapy 346hp corrected at the wheels with #7 giving 70psi cranking cr vs the 160 on all others...that was with ported square port heads (iron) and a compression in the mid 9 (static) ... so I wanna make sure I'm doing things the best I can...

thanks for the advices! keap'em coming!

ps: the goal is 600 or more fwhp...there was a build up in chevy mag that did 576 with my cam and oval heads...I would think I should be able to make the 600 mark with the canfields. (?)

 

You have more than enough cam in the 288AR and 10.0:1 compression.
I don't know Canfield's heads very well but that cam, a single plane intake and a good set of oval port heads like Brodix's, will put you well into the 600 hp range with close to the same amount of torque. Should have close to 500 lbs ft from 2500 rpm on up so I don't think you're really giving up much here. Not to mention, your converter is rather mild.

-Mindgame

 

yes it is mild, but it stalls a little higher than that...really nice for the street..probably could use a little more of it (nothing that I can't change later...).
I think if I get the heads shaved a little, with 0 deck clearances and a 39 gasket (vs 41) I might be able to squeeze 10.2....

plus now that blue bottle is geting tempting....ya know like a 125 shot just to spice it up a tad (again not to much because it's still a studed 2 bolts)...

 

stock bottom end LT1s have shown to be able to stand up to 200hp 2 stage nitrous hits. That's with a cast crank, hypereutectic pistons, and 2 bolt mains. I wuldn't be afraid to hit that Rat with at least that much juice

 

usually it's a question of rpms rather than power, for rats, 750hp and 7000rpms is about what it will take...my belief is that as long as you don't leave each light at 5k and shift every time at 7000, a 2 bolts can handle the "street" (even with 200 shot and even a 7000 shift...) but I won't open a discussion cuz I know better !

well looks like I'm gonna go the 10-1 route...and spray it a little too (since I already have a cheater system siting in the garage)

 

I am not sure about big block chevys, but Fel Pro makes a shim gasket for small block Chevys that is .015 thick.

 

CHP ran a 300 shot on a junkyard motor, just because you can do it a few times doesnt mean it's right.

 

they did destroyed the motor as well....

but I'm not going to do that! 150shot max

 

that's a smart *** responce

One of the impala guys that did this ran several bottles through his engine and it is still going strong. He did have a bigger than normal cam (224/236 113LSA) that bled off some of the juice, but just about any big block will have an even bigger cam than that. You just need to put some time and money into a safety system and not get too greedy.