Stock vs. Forged Shortblock
Stock vs. Forged Shortblock Alright guys, so I have an LQ4 setup in progress that's going into my RX-7. It consists of a Turbonetics TC76 (.96 a/r, F1 housing), 48mm Turbosmart Pro Gate, 50mm Turbosmart Raceport BOV, etc. The car is a street car and will have all necessary supporting mods. I was originally planning on a partially forged shortblock with forged pistons and rods. Now I'm debating on whether or not it's worth the extra $3,000 for the extra 100RWHP. I was shooting for 700RWHP but now it seems a lot easier/cheaper to just go for 600RWHP with a stock shortblock. Any thoughts on this? I live up in MN so the car isn't driven that much... just to and from work and around on the weekends... if it breaks it's not the end of the world although I don't want it breaking all the time. I have a good tuner who will be using HP tuners. We'll be using 91 octane pump gas (that's what's available here).
I'd like some feedback from those that have gone both routes, and how happy you've been in either direction. I haven't read about too many people blowing up their stock shortblock LS motors at 600RWHP, but maybe they just don't post about it much.
Either way the car is getting a medium sized cam, pushrods, springs, ARP rod/head bolts and MLS head gaskets.
Pic of said car:
Pic of said engine:
Progress so far:
I'd like some feedback from those that have gone both routes, and how happy you've been in either direction. I haven't read about too many people blowing up their stock shortblock LS motors at 600RWHP, but maybe they just don't post about it much.
Either way the car is getting a medium sized cam, pushrods, springs, ARP rod/head bolts and MLS head gaskets.
Pic of said car:
Pic of said engine:
Progress so far:
I'm debating the same thing.. If your like me you cant leave things alone so I say Dont forge it now. Save it for when you upgrade your turbo. Cause you know you'll want to. 600HP is fast in a 4200Lb car (gto) not to mention a 2800 lbs car. So you should have some fun for a while. Maybe re-gap the rings to follow the Hot Rod build.
I'm running a stock short block with a smaller turbo. I don't expect to ever go over 10 psi with this setup. For a reliable street car, thats all i really want or need.
I expect to max out at 500-520 rwhp.
I expect to max out at 500-520 rwhp.
Things add up quickly when you have to pay someone else to do the work.
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I think at this point it's best to take the heads off, inspect the cylinder walls for scarring, throw in some rod bolts, put on new head gaskets, and put new head bolts in, and call it a day.
Thanks for the input guys. I think next winter I'm just gunna go with a bigger turbo and a forged 408
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It's a tough decision to make and you really have to ask yourself some serious questions as to whether or not you'll end up being happy limited to the power that a stock shortblock can provide. Maybe just run the stocker till it goes and then upgrade. I spun a rod bearing last year and used it as an excuse to drop around $4,000 forging everything before a turbo even went on. I probably have one of the most bombproof 300rwhp motors on the planet 
forge it now and be done with it, stock crank will be good at 700, pistons rods and bearings should beunder 1500 for pretty good stuff (not eagle garbage). i would just forge everything and boost the living **** out of it! my stock bottom end blew up at 450rwhp FYI (ring land)
I'm using a TH400. I don't have any ET goals since the car isn't really a track car. And I won't be heartbroken if I don't hit 600RWHP... it's just a goal. As a street car, in my neck of the woods, it's faster than 99% of cars on the road.
Zach: I think you're right on point. I should really get the thing together as is before deciding if I really need 700-800RWHP. 600 should be plenty. Hell, the car was scary at 400RWHP when I had the LS1 in it.
The quote from a good machine shop for a hot tank, hone, balanced rotating assembly balanced/installed, valve job, and PARTS was around $3,000. My debate is... for a car that is driven 2,000 miles a year, do I NEED to spend the dough to go forged. Yeah, maybe I'll decide to forge it later down the road. Right now, money isn't the problem (I can afford it) it's whether or not the cost is worth the benefit.
600RWHP is still stupid quick for a 2,800LB car. Does 700RWHP really justify the extra money? And if it blows up mid summer, I'll get the motor forged and be done with it - not the end of the world really.
My tuner, by the way, is like a mad ******* scientist (in a good way) and will be able to tune it safely.
I know it sounds like I have my mind made up but I DO appreciate the feedback.
Zach: I think you're right on point. I should really get the thing together as is before deciding if I really need 700-800RWHP. 600 should be plenty. Hell, the car was scary at 400RWHP when I had the LS1 in it.
The quote from a good machine shop for a hot tank, hone, balanced rotating assembly balanced/installed, valve job, and PARTS was around $3,000. My debate is... for a car that is driven 2,000 miles a year, do I NEED to spend the dough to go forged. Yeah, maybe I'll decide to forge it later down the road. Right now, money isn't the problem (I can afford it) it's whether or not the cost is worth the benefit.
600RWHP is still stupid quick for a 2,800LB car. Does 700RWHP really justify the extra money? And if it blows up mid summer, I'll get the motor forged and be done with it - not the end of the world really.
My tuner, by the way, is like a mad ******* scientist (in a good way) and will be able to tune it safely.
I know it sounds like I have my mind made up but I DO appreciate the feedback.
I would just forge it if you are going to be running 91, I would trust the stock shortblock more on E85
Plus if you loose a ringland you can probably say good bye to the turbine
That car will be a 150mph setup on that turbo without it even maxed
I am not even pushing mine and it is 150
Plus if you loose a ringland you can probably say good bye to the turbine
That car will be a 150mph setup on that turbo without it even maxed
I am not even pushing mine and it is 150
Your in MN, the biggest E85 state in the nation I believe. It is a VERY forgiving boost fuel. I'd run a stock short block but open up the rings a little, heads studs, some rod bolts and let-r-eat!!! That stock motor with those mods will make all the power you want in that little car. No need to drop a bunch of cash on a forged motor, instead, use it to buy a couple more junk yard motors to put in the corner of the shop, 
Why don't you just find a set of used forged rods/pistons on here and use your stock crank? Buy some rings/bearings then have the machine shop throw it together. I bet you'd only have $400 in machine shop costs
