383 Build Questions

[bRock]

I'm planning a 383 build on my 97 Z28 and have a few questions:
1. This will be a DD and I have to consider emissions. I want to tune out as much of the emissions as possible that I don't need for performance/gas mileage. I was thinking EGR, AIR, EVAP; what about deleting cats? I'm guessing I need them to pass a stick test (I never get visual tested on my cats, even tho I'm supposed to). What about O2 sensors? Does going into closed loop improve gas mileage or can I get same results in open loop on the maf signal alone?

2. I don't have all my details laid out yet, but planning on 400+ HP and at least that in torque. I'm hoping my 6-speed will handle it, but worried about my rear-end. Haven't done much research here yet, but saw a write up on stiffening up a stock rear-end I was considering. Also saw some people getting a Ford 8.8" rear. I feel that a new Moser 9" is more than I need since a DD. Any ideas on that?

3. Wanting to run LT's and X pipe out the back w/ MagnaFlows; saw a few writes ups on this, but could I run both pipes over axel on Passenger side like the stock exhaust (maybe w/ simple modification)?

Any other ideas you guys have will be very much appreciated as I'm trying to get started on my homework now. Planning on doing this build in the next month!
Thanks in advance!!

[95ImpySS]

You will need all your emissions systems on the car. You will need your cats. No way at all you'll be able to pass with out them. Closed loop most definitely improves gas mileage. In open loop the engine is running on predetermined values. The O2's help fine tune the fueling and reduce emissions as well as fuel consumption.

T56 should take 400 hp/lbft well if not regularly abused. Stock 10 bolt wont be happy. Stock 6 spd cars blow up stock 10 bolts. Something to think about when adding power.

Getting a car to pass emissions and make 400 hp and torque is going to be a expensive tuning intensive task. What heads are you planning to use? Compression ratio?

[RamAir95TA]

The common misconception here is that by removing emissions components you'll gain horsepower while in actuality it's false, if not the opposite. You'll need every emissions component working PERFECTLY, seriously intense tuning, and some luck. Truthfully I'm not so sure I've ever seen a 400whp car pass emissions. It also depends on how stringent your emissions testing actually is.

If you don't take the car to the strip often and don't use a sticky tire your 10-bolt will last just fine. Gamble with sticky tires and it won't last long. Do yourself a favor and don't beef up the stock 10-bolt - it's just a wasted effort. Put that $ towards a 9" or a 12-bolt.

[1badz]

+1

[bRock]

Getting a car to pass emissions and make 400 hp and torque is going to be a expensive tuning intensive task. What heads are you planning to use? Compression ratio?
not sure on that just yet. I'm trying to get this thing done in about the next month, so I'm kinda rushed. I wasn't really prepared to do it right now, but the opportunity presented. I was going to keep the top end pretty streetable. Planning on keeping the stock heads and intake if possible and doing some port work, not sure about other specs yet; I going to dig around a little. Keeping it naturally aspirated, though.

[bRock]

The common misconception here is that by removing emissions components you'll gain horsepower while in actuality it's false, if not the opposite. You'll need every emissions component working PERFECTLY, seriously intense tuning, and some luck. Truthfully I'm not so sure I've ever seen a 400whp car pass emissions. It also depends on how stringent your emissions testing actually is.

If you don't take the car to the strip often and don't use a sticky tire your 10-bolt will last just fine. Gamble with sticky tires and it won't last long. Do yourself a favor and don't beef up the stock 10-bolt - it's just a wasted effort. Put that $ towards a 9" or a 12-bolt.
Good advice. That's kinda what I was hoping for :) I may try to get my car registered in another, non-emissions, county. It doesn't sound like emissions are that strict here in GA compared to other states. They just test gas cap, stick the tailpipe, and hook into pcm.

[RamAir95TA]

Without emissions requirements the same money you'd spend on trying to get it to pass would go so much further in a non-emissions performance application. Definitely go that route if possible.

Also, if you still end up needing to pass emissions, a stock-displacement build will be a bit easier to pass than a 383 with the same heads/cam.

[bRock]

Without emissions requirements the same money you'd spend on trying to get it to pass would go so much further in a non-emissions performance application. Definitely go that route if possible.

Also, if you still end up needing to pass emissions, a stock-displacement build will be a bit easier to pass than a 383 with the same heads/cam.
+1
I might be able to register my car in a non-emissions county; that should do it!

[95ImpySS]

Good info in this thread. I would recommend not using stock heads on a 383. If anything get them extensively ported & polished with bigger valves. Otherwise your going to make peak power at like 3500 rpm lol. From one enthusiast to another. Rushed build are very prone to failure. Unless you have done the work a few times you should really take your time. It could all end up in wasted effort. Good luck

[bRock]

Good info in this thread. I would recommend not using stock heads on a 383. If anything get them extensively ported & polished with bigger valves. Otherwise your going to make peak power at like 3500 rpm lol. From one enthusiast to another. Rushed build are very prone to failure. Unless you have done the work a few times you should really take your time. It could all end up in wasted effort. Good luck

I've been doing some research for maybe 6 months now, but I still feel rushed. I have a great machinist who's helping me and a mechanic friend w/ a lot of experience; I was wanting to do port work and bigger valves w/ the stock heads, and maybe similar to LT4 specs on the cam. Again, I'm still researching, so not sure on exact specs yet. Thinking about letting her breath on the top end more than stock though. My biggest concern is not getting too aggressive with the build. Thanks for the advise! I'll be sure to take as much time as I need to get it done right!

[LT1RUNNER]

Im in AZ and emissions suck!

[RamAir95TA]

Out of curiosity, what kind of budget are you working with?

[bRock]

Out of curiosity, what kind of budget are you working with?

Trying to keep it around $5k, maybe as high as $6k if anything goes wrong or I get carried away! lol

[95ImpySS]

Do you need to change your crank, rods and pistons? Reason I am asking is because a set of decent ported heads, with new valve springs and a cam to match is going to run you anywhere from $1600-$3200. A cast stroker kit will run you around $1000-2000. Then you factor in balancing, bearings gaskets, etc. Then most people add on roller rockers, bigger valve covers to fit the rockers. Hardened oil pump drive shaft and gear, new timing set, etc. If you go 383 you'll need new injectors, modify the factory throttle body or go aftermarket and then mod that. You should also upgrade the fuel pump, change motor mounts. SO many factors. So may other little costs that just ADD up.

[bRock]

Do you need to change your crank, rods and pistons? Reason I am asking is because a set of decent ported heads, with new valve springs and a cam to match is going to run you anywhere from $1600-$3200. A cast stroker kit will run you around $1000-2000. Then you factor in balancing, bearings gaskets, etc. Then most people add on roller rockers, bigger valve covers to fit the rockers. Hardened oil pump drive shaft and gear, new timing set, etc. If you go 383 you'll need new injectors, modify the factory throttle body or go aftermarket and then mod that. You should also upgrade the fuel pump, change motor mounts. SO many factors. So may other little costs that just ADD up.

Yeah, true that! My machinist quoted about $800 for a Scat cast crank, rods, pistons, and 1.5 rr's; still gtta factor in top end components & labor. He said he could do it in my price range; and a very reputable guy...I've used him before when I restored my '68 R/T Charger. I was trying to keep stock injectors/fuel pump/TB. Planned on new timing components. I need to finish my list and pricing everything out.

[RamAir95TA]

I hate to say it but the overall approach here has me worried, given your builder's choice of parts and the budget. Your top end/valvetrain alone in order to achieve that 400whp mark is going to be an easy $3000. I'd consider reusing the stock crank, forged (or even stock) rods and a decent forged piston. Reusing some of the stock parts here won't compromise overall strength of the bottom end while freeing up some budget for where you NEED to invest the $$$.

I suggest you find a build that does what you want it to do then look at the parts list - then emulate.

[bRock]

I hate to say it but the overall approach here has me worried, given your builder's choice of parts and the budget. Your top end/valvetrain alone in order to achieve that 400whp mark is going to be an easy $3000. I'd consider reusing the stock crank, forged (or even stock) rods and a decent forged piston. Reusing some of the stock parts here won't compromise overall strength of the bottom end while freeing up some budget for where you NEED to invest the $$$.

I suggest you find a build that does what you want it to do then look at the parts list - then emulate.

Yeah, that's a good idea. My original idea was to use the stock bottom end and do an LT4 conversion. I got to reading some and messed with the idea of just machining the heads and intake to what I wanted to do and throw a cam in it. I'm not set on a 383 build and I'm gonna talk to my machinist early this week to plan the build. He builds race motors everyday, so really he's the genius behind everything! I'm just trying to learn as much as I can along the way.
And, if I had to, I could prob increase my budget if I needed, but I'm trying to keep it in the $5-6K range.

I'll update early this week hopefully with some more detailed plans. I'm pulling the motor tomorrow.

[95ImpySS]

RamAir95TA has nailed it!!!!

Be careful doing what they say. My machine shop swore up and down that I couldn't run higher than 10:1 compression using pump gas on a SBC with aluminum heads. (LT1 is 10.5:1 from GM) Many have done it. Even after I just helped finish a 12.5ish:1 LT1 that runs fine on 93. Good luck and check back in.

[bRock]

Thanks, I sure will.

[bRock]

Question on fabbing up x pipe exhaust: Will I need to install a panhard relocation bracket in order to run dual pipes over the axel on passenger side? I can't seem to find the answer to this anywhere, but it looks like I would need to.

[bRock]

BTW, here's the Z (disregard the "old" car behind it! lol) and some tear down pics.
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