...alright guys, picked up a used 4 bolt main, 350/L31 motor with the .062 heads, and I'm looking to have it built/machined "hopefully" in the next 6 months or so. ...I have a friend who's gonna get the business from me, and his engine builder and I have been talking a little.

....I have NO doubt he's not trying to over sell me, but I think he may possibly trying to play the better safe than sorry approach, and I'm not sure really what my budget is just yet. I know he wants to cover himself, but at the same time, there's a LOT of money involved in "playing it safe" ya know!!!

Here's the round about goal:
275-300 "ish" RWHP out of the soon to be 357ci. block with a modified TPI, and I'd like to see if I can't push 400 RWHP with a shot of nitrous. If we don't quite make it, that's fine, but at least you see where I'm going with this. This will NOT be a race car, rather a show and shine weekend driver, and on occasions....well....you know!!!!!!!

How much shortblock do I need? I see guys puttin' numbers like this down on stock L98 bottom ends, albeit not what you might recommend. I dunno, just looking for some conversation on the matter. He and I are looking at a fully forged set-up right now, and I have this vision of overkill!!!!!!

Whatha think????

 

Forged if power adders are in your future. Have you considered going the 383 route?

 

TRW forged pistons and the stock crank and rods, with a good balance job and ARP main studs and ARP rod bolts and you'll be fine at that power level. Why a 357 and not a 355? .030 over pistons are typically cheaper as well.

 

For the record, I was pushing 500+ RWHP on spray with my stock bottom-end LT1 before one of the piston's finally let go. That was due to the fact that IAT sensor wasn't reading properly and caused my engine to go lean by the way, not because the piston's couldn't handle the stress. Had it not been for that damn IAT sensor, the motor would still be running....

I'm not exactly recommending you use only the factory (cast) parts (obviously I was pushing the limits of the stock bottom end with my set-up) but it's just to give you an idea of how far you can push a motor without having to spend big $$ on expensive forged internals.

Since you've decided to stick with TPI, that alone will save a lot of wear/tear on your rotating assembly given the fact that at most, you'll only be spinning your motor to about 5500 tops. Remember that the higher you spin a motor, the more stress you put on the parts. (I've noticed TPI motors tend to last noticeably longer than the newer LT1/LS1 motors do)

Having said that, since you also want to spray the motor and try and hit the 400hp mark at the wheels, I'd recommend (at the very least) you spend some extra cash into picking up a set of forged pistons.

SRP (a division of JE pistons) offers some really nice forged piston's at a great price. They're really strong and are (in my opinion) the best bang for the buck pistons on the market) Definitely worth looking into for your build-up.

As other's have already mentioned, you can easily get away with re-using the factory crank and connecting rods as they're more than adequate to support the power-levels you plan on putting out. But the forged pistons are definitely a must if (for no other reason) they give you "peace of mind" whenever you hit the spray

Pistons are always the first thing to let go using a power-adder. Especially Nitrous Oxide. So if you're going to spend the money on anything, it may as well be on a set of forged pistons.

Rebuilding a motor doesn't have to cost an arm and a leg so long as you have a basic idea of what your goals are with that motor. In your case, you can achieve what you want with very little money involved.

A little off topic, but, do you have any idea on what heads and TPI set-up you plan on using? What about the Nitrous? Are you looking to use a wet or a dry system?

 

....Since I wanna keep the TPI, I don't wanna go too big. I know, I know, there's power there, even with a TPI, but for the additional cost, I just think it's something I don't really need.

The guy said they often see Vortec motors that need an extra .010 to clean up well. I've had others agree with that statement. Why? I have no idea. At this point, for quoting purposes, that's fine with me. ....although, this motor has about 60,000 miles, so ya never know, it probably won't need much if anything. ......but you asked, so that's why 357 not 355!!!

See, that's my logic too. Not saying stock is the way to go, but I don't really think fully forged is necessary either. ...but I'm no expert either.

I've got the .062 heads on the longblock now as it stands. Plan is 2.02/1.60 valves, and some "stage 1" porting on those heads. The guy says they see 400hp at the crank with those heads (stock) quite often with a big cam and carb. We both agree that a little cleaning and smoothing here and there makes sense since there gonna be off the motor. ...and of course they'll get the necessary machining and screw in studs for a higher lift cam.
As for TPI? Again, some minor porting and matching on a Vortec TPI manifold with some ported SLPs and ported plenum. This could change of course, but that's what's in my head as of now!!!
....as for nitrous, well, I'm not an expert on that yet, and it'll probably be awhile. The motor needs to be up and running, tuned, and the kinks worked out. THEN "maybe" nitrous. Ya wanna know my logic for this whole thing? At G11 last year, about 10 of us were cruising back to the hotel and I was out front, but of course we weren't racing. A Cobra pulled past all the 4th gens, a few of which were WAY north of 500hp, and started reving at me.

....I have NO intention of building some money winning street legend of a racecar, but a little nitrous will help me feel a little better 'bout myself here and there!!!! LOL

 

Steel pistons? Whoa, i'd have to see those...

I don't think you'll need to go up to 2.02 valves on vortec heads. I don't think it's an upgrade, like it was on older head styles.

I think forged TRW, or gasp, hypereutectic pistons would work just fine. I'd use some mid-level I beam rods (Eagle stage 1, maybe summits stage 2, etc), with ARP bolts. ARP bolts, or studs for the mains, and you're set.
A steel crank should be fine as well, I don't think you need to get into forged territory with the RPM limits of the TPI setup. The crank sees stress from the rotating inertia forces, ie, 6500RPM + --> I don't think you'll be up there much.

 

Sorry 'bout that, it was a typo. I originally wrote a few things about the benefits of having a forged steel crank but decided it wasn't very useful given the fact he probably wouldn't need one. I deleted that bit but for some reason the term "forged steel" stuck in my head when I wrote about the pistons. Sorry.

 

2.02 valves will be of no benefit in a Vortec head. The chambers will shroud them negating any benefit of the bigger valve.

Get a budget together and tell the builder what it is. Tell him what you want the engine to do. If you trust him enough to build it then leave it there and let him build it. Don't try and do his job for him. If your goals are unrealistic based on that budget I'm sure he'll let you know.

 

a cast steel crank like a scat 9000 would be more than ok at the 350-400hp level

stock rods are marginal and best replaced,as much better rods are dirt cheap


hypereutectic pistons will work but ID seriously suggest forged if nitrous is EVER a potential possiability in the future

buy a COMPLETE MATCHED COMPONENT, BALLANCED ROTATING ASSEMBLY

http://www.adperformance.com/index.p...roducts_id=665

 

Nope. Not me. I couldn't disagree more. This thread alone has different opinions on what is needed for my goals. I've read books with conflicting info, and I'm sure 10 different engine builders will have their different opinions as well. I'll read, read, read, and then make a choice, with "my guy's" opinion weighing heavily, but ultimately I'm gonna make the choice based on the info I've been given. Dont get me wrong, he's a professional for a reason, and I respect that, but forged, cast, hyper etc. etc. are pretty big details IMHO.

Can you port the chamber to unshroud the valve? He didn't specify either way whether the head porting would do this when we last talked.

 

So is he turning the wrenches and building the complete block for you, or just the shortblock, or just doing the machining?

You can deshroud the chamber, but Vortec heads are the type of things where you don't want to mess with success eh? I really (really!) don't think you'll gain ANYTHING by going up a valve size and deshrouding. It's dicey if you get more gain than harm, you open up the chamber, drop the CR, perhaps throw off the wicked nice swirl properties that make that a rockin' head.... If the porter is GOOD, and has portec VORTEC heads successfully before, then i'd flip a coin on it. Otherwise, i'd avoid it. Most people use vortecs as is (without larger valves) and see pretty awesome results. Personally I wouldn't chance it if it were me.

Abubaca - Please read this
http://kb-silvolite.com/index2.php
article on ring gap. This isn't specific to Keith Black pistons BTW. I'd highly recommend you set the ring gaps wide, as you can see oil consumption is barely changed by going FREAKIN' HUGE. Many failures from nitrous is ring butting (aside from totally off fueling causing catastrophic meltdown).

You didn't mention a camshaft choice yet eh? I'm thinking in the CompXR270-14h range?

If you aren't buying all the parts from your builder, I recommend looking at ohio crankshaft for some of the bottom end. They had some nice inexpensive rods there, and their speed-pro pistons were priced on par, or slightly below summit.

 

is this a daily driver, 30000mile a year, beat the hell out of it, type of car?

As long as your not looking to get a million miles of beating the snot out of it you should be fine with a half decent cast rotating assembly. If your going to spray or boost, or plan to in the future then your better off spending a bit more now for a forged bottom end rather than buying 2 seperate ones!

 

If you don't trust them enough to make the right decisions then it's time to find another shop. He's been doing it a lot longer than you so don't expect to be some expert because you read some books. There's always different ways of getting to the same goals. The general consensus here in this thread has been that you need forged pistons becuase you plan on a small squirt. How is any of the information here confliciting? You could build a milder 383 that would make the same power as the 355. Different roads to take

 

For your purposes I think an Eagle crank/rods with a set of Wisecos or JE's would work well. Chances are that a stock crank is going to need some work to be used in your engine and in the end you still have a used crank that could have some undetectable damage. A cast crank from Eagle is less than $200 while having a stocker cleaned up and checked over is going to be close to $100 and that's assuming it doesn't need to be ground.

I'd rule out stock rods, especially with the spray. If you install a set of ARP bolts in then the rods need to be resized and trued up. They'll also need to be pin-fit to the new pistons so by the time you've got the bolts and work done you're looking at around $200 and you still have stock rods with a pressed pin. If you upgrade to an Eagle H beam you'll get better bolts, a stronger rod and the option of running a full floating piston. A set of 5.7" eagle rods runs around $400.

I would get an Eagle kit. They come with SRP pistons that aren't the best but they'll work ok for your setup. It also comes balanced and includes rings, bearings, balancer and flexplate. The entire kit comes in at just under $1900. Then count on another $500 for block prep, then a cam, timing set, oil pump, pickup, and other little odds 'n ends.

 

It's not a matter of trust, but I want to know WHY we're doing what we're doing. If he says I need part A and not part B, then I trust him, but I also want to know why. That's not too much to ask I don't think.

.....and BTW, I really appreciate the feedback. Seems to be the consensus is pretty consistent with what this guy has been telling me. As I mentioned, I think he's just being careful by suggesting forged rods, and some of you guys have mentioned them too.

....he hasn't layed out an entire plan yet, we've kinda been talking in bits and pieces. Hopefully we'll sit down and discuss it sometime next week. We're going to discuss cam at that time too. I'm thinking "around" LPE219/LT4HC/ZZ9 "ish" size. ....again, we haven't got to that yet.

...and as for the valves/heads, I'm glad this was brought up. I'm gonna talk to him about it, and do some research. I've seen good power out of stock size valves too, but I've also heard of people going bigger. Perhaps they didn't get anything out of it though....

Thanks again!

 

http://www.cnc-motorsports.com/produ...074&CtgID=1020


forged crank, h beam rods, srp forged pistons, rings and bearings $1439 + 90 more if you want them to interal balance it.


I got my 383 eagle competition kit from them.

 

have the heads bowl blended that's it. No bigger valves and save the $$$ on porting, since you'll be already outflowing what TPI can support regardless. Have them machined for higher lift, screw-in studs, and open up the spring pockets, along with setting them up for the .563? whatever size positive locking valve seals on intake and exhaust. I believe it's .563 but it's been a while since I looked, jegs and summit sells them. Other than that, build the shortblock that I talked about earlier, and it'll hold up for a long time and not cost you extra $$$ in parts you don't need. The motor won't be spun to the moon with TPI so there's no reason to go fully forged, a good balancing will be fine. If you need any other info let me know. Also, I thought golen engines was from NC or SC and they sell all done up shortblocks for not much cash.

 

Totally agree. Decent FORGED pistons (TRW forged,,, ok - the Keith Black FORGED are a little more $ but very nice for the money), resized rods with ARP bolts, ARP main studs, stock crank, and balanced is all you need unless you plan on running the nitrous all the time. As long as you are properly fueling and timing the nitrous and running under 6000,,,, that'll hold together without problems. I've built a number of these type short blocks in the 500 horse range off the spray and guys,, including myself have run a 150 shot on them often and 250 shot on occassion. The machine work on the engine as well as the tune on and off the nitrous MUST be right. If you're inexperienced,,, maybe the forged crank and rods might let you sleep a little better at night,,, but generally you're going to hurt a piston land on the spray before you'll hurt a rod or crank with a low RPM (under 6000 rpm) engine. Actually,,, the stock valves in the heads will come near giving you trouble (with the nitrous) than the above mentioned assembly for your power level. I'd spend the money on a good set of stainless steel under-cut stemmed 1.94 valves and bronze guides before spending the money on the crank and rods,,,, other's opinions may (and appearently do) vary.

Ditto on the ring gap statements,,, needs to be enough for the level of nitrous you're planning,,, follow the manufacture's gap suggestion,, if there is a range,,,, go on the lower side for small kits,,, higher side for large kits.

IF you decide to change the crank out,,, go ahead and get the 3.75 stroke and matching pistons. If you're going to buy rods,,, go ahead and go with the 6" rods for the 3.75" stroke on the spray. The difference is usually under $100 (if that much) and it'll be well worth the extra money spent.

 

Guys, can't tell ya how much I appreciate the feedback. While I can't rattle everything off the top of my head, I've got a pad of paper with all these little tips and ideas!!!!!

...I don't want to (as Dialed In mentioned) do the engine builder's job for him, but I do want to ask him about a few of these things. ...and that's not to say he wouldn't have done 'em anyhow, but I know that I AM certainly learning!!! LOL