What would be an ideal bottom end to handle 14 intercooled psi on a 350 with a P1SC? I was thinking Manley H Beam steel rods, a set of forged blower pistons and a forged crank to start with.

The pistons and the crank are the only two things where I havent decided what I want to run. Are factory forged GM cranks any good, because SDPC2000.com sells them for right around $500. What are good blower pistons? Thanks,

Seth

 

I believe factory GM cranks are 1053 forging where as many aftermarket ones are either 5140, 4140, 4340. These are all techinically stronger than the GM crank. Low compression is key when running high boost motors. I'll be running 10psi on a non-forged stroker motor but with 9:1 compression

 

I noticed that, yes they are 1053. I was planning on like 9:1 or 8.5:1 compression for that much boost. Do you guys think I would be better off with an aftermarket forged crank, or will a GM crank suffice?

 

if you are going to do it and money isn't an option do it right. i plan on doing an al 4340 forged 427 small block this winter and run 12PSI twin intercooled boost w/a 50-100hp shot of N20 also. so......... lemme know if you get the all 4340 motor and break something w/ only 14PSI boost and no N20 so ic an change my planz :-D LOL

later

Josh

 

With a 4340 setup, 14 psi isn't really that much. The 4340 will more than handle it. Just make sure to have compression down to the area of 8.5:1 or something around there.

 

I dont like the stroke to rod ratio of small block 427's.

 

do a 355 with 6.0" rods, thats got a good rod ratio.

 

whats the big deal on stroke to rod ratios? just wondering..... thanks

Josh

 

Running such a big stroke with such a small rod is hard on the cylinder walls.

 

ok i though that was the only problem but didn't know if there was someting i didn't know. thankx,

Josh

 

I would say it really depends on your estimated output. If you are slapping a 15psi charger on a stock head and intake combo than you shouldn't make anything more than 500 horse. If this is all you are looking for, go with a cheaper aftermarket 5140 kit that uses trw dished pistons. I personally run all 4340 with a 15 psi P1-SC, however it is boosting an aftermarket headed and intaked 355, and double duties with a 150 shot stacked on top.
BTW, I am running 7.8:1 compression
I would suggest a 4340 eagle crank over the gm piece, and hang some trw -30cc pistons off those manley rods.
Good luck

 

Not much of a price difference between 5140 and 4340. When you're spending that kind of money, its better to go all the way and not skimp on anything. I personally don't think the heads and intake have anything do to with the strength of the bottom end. I see what you're saying about the hp limits, but don't see how a crank or rods knows how much hp you're making. Can you elaborate more on the head and intake and how that affects the strength of the bottom end.

 

What I mean is that if he is running a good set of heads, and a good unrestrictive intake system, that 14 psi that previously made 500 horse on a stock flowing tpi engine, is now making 750 horse, thus requiring a stronger bottom end.
I agree that he should just go ahead and get the 4340 goods, but I would definitly not say there is not much of a price difference between 5140, and 4340.

 

The motor makes around 425 horsepower.

 

what about a forged 4340 bottom end, -17cc forged pistons, P-1SC and 16psi, AFR195's and LTR, 355. around 475fwhp. completly streetable.

 

there is a guy/company selling eagle 4340 cranks for $369, this link is to one he's selling, it is a 377 crank, but its just an example, oh and they are rated to 750+ HP i believe, also he has eagle 4340 rods for $350 rated to 750 HP too i believe, or you can pick up some "powdered metal/pink" rods from GM, they come in all LT1's, vortec blocks, and zz4 motors and GM rates them at 500 HP (ive heard thats under rated too) you can get those used in good condition for DIRT cheap!
and last... a mechanic i used to work with builds a lot of motors for people out of his garage, he put a D2 blower on this kids 95 LT1... its completely stock internals, and 10.5 compression running 10 psi, he's had it on there for about 1.5 years, driving it hard, without breaking anything as for power it hasn't been dyno'd, but on some cheap 18" dunlops or something he ran a 13.0 in denver (so a 12.0 at sea level) with lots of computer problems, they cant figure out where to mount the maf sensor, mounting it where ATI said it ran a 13.2.. they moved it and got .2 sec, but think they can do better, also they keep throwing codes, and said its running very rich, they are hoping for mid 12's when its all fixed, again thats mid 11's at sea level, so my point is 14 psi from a p1-sc with low compression although 4340 would be recomended, it may not be necessary because if your racing it chances are rings and bearings will go before some DECENT pistons, rods, crank will go... i personally would use the powdered metal rods, nodular iron crank (found in same motors as powdered metal rods) and a decent set of 9.0-1 forged pistons

 

lol, i forgot to include that link i was talking about, and the guy is on ebay

http://cgi.ebay.com/ebaymotors/ws/eB...tem=2443983635

 

I know, thats cnc-motorsprots. Clint is the sales manger and he priced out a complete long block w/ forged bottom end, x276hr-14, roller rockers, AFR heads all the works for about 4 grand. his prices are greta and so i hear is his service.

 

How high are you going to twist the motor?.
Syclones ran 14+ PSI on stock GM stuff, but kept the rpm down.

The key is tuning, at 14 PSI just a little detonation can do alot of damage.
Too small of injectors, and things like FMUs aren't the best answers for keeping it alive.