Hey guys.
After last weekends autox, looks like I don't have much time left on current motor.
In a perfect world. what is the best combo motor application for RR. Whats the typical RPM range I need to build for? I am AIX. By accident I have 3rd gen with T56, C5, brakes, ZR1 11" wheels. So lets build something that will kick some a$$ but have good longevity. Using Iron roller block. Is the Moroso RR oil pan good? I have L31 heads, .512 lift crane hydraulic roller cam, vortec intake and 800DP Holley, 15/8 headers. SRP inverted dome piston and eagle rods. My question is: 383 or 350 ci. Open for suggestions. Going to build this over the Thanksgiving holiday Thanks Jarrod

Be money ahead .... GM Performance Crate motor.

/thread

Sounds like you already have most of the parts you need for a 300ish hp motor. For that head / cam combo, definitely go 350. A 383 or bigger will make the same hp but at a lower rpm. The small amount of torque you'd gain isn't worth the loss of rpm range IMO. Also, an 800cfm carb is WAAAY too big for this combo...sell it and get a 650ish model. The Demon carbs are really nice if funds permit....

Invest in some Plastigauge and good books....pay very close attention to both static & dynamic compression ratio, quench area, bearing clearances, etc. Have a good machine shop balance the rotating assembly and prep the block.

Or - as Mitch mentioned - save yourself a bunch of time, money and potential headaches via a crate motor or long block from a reputable source. Really takes the guesswork out of the equation and you pretty much just buy as much power as you can afford. Especially if this is the first race motor you've built....takes most people two or three shots at it to learn all the "tribal knowledge" details and assembly tricks that go into a reliable track motor.

Is that a question? I assume so. If my world was perfect I'd have an injected SB2.2 stoked to 410 cu-in


Nice to meet you AIX


How much money do you have?


Dunno, most people here use Canton Pans.


This doesn't align properly with "In a perfect world. what is the best combo motor application for RR."


There's no replacement for displacement.


I'm not trying to be a complete jerk, but we need more facts and better questions to help you out here.

username = IROC383 =

383

again ...

There's no replacement for displacement.

~DaVe

Thank you all for your input. My engine builder is getting ready for my application. just wanted to hear everybodys wish list on motor combos. SB2 would be sweet I agree. Thanks again. I'll keep you all posted.

I start by swagging the top speed I'm going to achieve on the tracks that I frequent. If you have an early (.82 5th) T56 then you can use 5th, otherwize plan to limit yourself to 4th. That decision will determine what rear ratio you use, and that ratio, along with your rear tire diameter, will give you maximum RPM. Build the motor to redline a couple hundred rpm higher - if that gets too expensive then rethink rear ratio, or tire diameter.

On the bottom end, with the relatively wide ratio T56, you'll find yourself under 3500rpm more often than you expect, so don't over cam it. More displacement will help here, as will lower total weight.

383 small blocks suck. Don't build one.

Thanks Blaine Fab,
I have the 93 T56 so 5th is a little low but usable. My rear ratio is 3.73 with 11" ZR1 17". I will run Sebring. Road Atlanta. Nashville, maybe Roebing Road. Good hot 350 or a stroker 4340 cranked 383. I do some Autox to go through the process of loading and running the car. I just want to make wise use of time and money. I have a credible race engine builder that's going to do what I want with tq, rpm levels in mind. Checking with all the Pros here at FRAXX.
Is there a special hei distributor, rev limiter, spark plug wires, etc to use.

That's easy:

# smitty new_engine

Follow the prompts, providing input, as requested. A reboot isn't necessary afterward, but recommended.

whats that mean?

I have no idea what that means either but I can tell you this...You are not going to kick anyone's axx in AIX with the combo you're talking about here. You're not that far south from the Great Lakes Region and could end up running races against two of the fastest AIX cars in the country and if you ever think about running the Nationals at Mid-Ohio you'll run against them for sure. It takes 600 to 800 RWHP to even think about being near the front in AIX. What you definitely are going to run into down south is a former AS racer from Florida that is converting his car to AIX. He's got a thread on the Nasa forums with photos of his new mods. You need to step back and look at AI.

AIX is for two kinds of drivers: Ones that have the money/resources to do it right. These guys have fast cars and know how to drive them. The other group are guys with 400 hp and an excuse that they can't run AI. They want to be fast but don't have ability to run at the front of AI and in the twisty stuff usually have an CMC or FFR car up their axx!

Choose wisely,

Sidney

Then maybe SCCA and NASA will change rules because Im not buying more stuff for my car. Started this set up in 1999 besides, getting on the track and starting a race is like winning in a sense. Lots involved in preparation. I'll never have a 600 hp rwd engine to race. I'll run AI if they will take 11" wheels, 6speed in a 3rd gen, c5 brakes and high 400 hp. If not then, looks like I'll finish last in AIX with a smile across my face. Anybody agree?

NO.

The idea of racing is the competition with another dirver. Not really what place you end up. I don't care who you are; you're going to get tired of watching those monster AIX cars run away from you as if you're driving a miata. To me it sounds like you haven't even read the AI/AIX rule book yet. Do yourself a favor and read the rule book and build from there. You might actually save yourself some money by eliminating parts you thought you needed. Or there is the ST group which like AI has a power to weight ratio rule. ZO6's tend to run ST1 or ST2; just to give you an idea of what's in the class. AIX and STU are classes that remind me of the can-am cars. Big tires, big power and little weight. You really have to step up in those two classes.

So trade the ZR1 wheels for something 9" wide and build a 350 that can handle 400 hp but tune it to put down 320 at the wheels. Put some weight in the car where you need it, slap AI stickers on the side and actually have fun racing door to door with some guys.

^^+1 When I get to wheel to wheel I want to be comparable to the cars in the race. I think it will be more fun when the competition is more on the driver. I would get frustrated if I kept getting lapped because I could not put reliable high horsepower down. I am on the fence of either CMC2 or AI. AIX is just too much for me

You need to stop while your ahead. This statement is so contradictory with what you say you want to do its shocking. Every time you open your mouth ignorance just spills out and washes away any respect anyone has for you. If you want to compete, read the rule books for each class, make an honest assessment of where you fit with your budget and skill level. Guys here can help you with those recommendations AFTER you have read the rules and know what you're talking about. Then you build the car to suit the rules, it is not the other way around. Building a race car means you build to someone else's rules. If you want to be hard headed and build the car they way you want, you can do that but you'll never compete wheel to wheel.

While a little harsh...it's also spot on. We've all been there, done that. You asked for advise and you are getting it. We're not a bunch of poser's that meet at McDonald's to talk about "kills". I've had my full comp license since 1999 and did plenty of open track stuff before that. I've raced mostly F bodies but spent a couple years in a 944. I've raced in ITS, AGS, AI, CMC1 and CMC2. If you want to race wheel to wheel then listen to this advise. You're heading down a path that will most likely end with you disgurished and broke with very little actual w2w experiences.

Best advise I can give is start out slow. Speed costs money and time. Time spent building and time spent sitting in the paddock with a broken racecar. You need seat time first. Slow helps to pay for track time. Track time is what makes you faster...not $$$'s. Fast is relative. I did a little over 140 mph at Watkins Glen in October. Try that door to door with another CMC car and tell me that's not fast and a thrill! One can take a Camaro from CMC1, to CMC2, to AI, to AIX. If you can run at the front in CMC...you can run at the front of AI or AIX but it's going to cost a lot more money and time.

Sidney

Thanks for all the kind words and advise. Sidney, you've made good sense. I have found general comp rules but not any details on classes, hp, wheels sizes, weight etc. If you could share a link to the nasa ccr i would love to follow your lead. Engine hp is 320 to the ground. I'll work on that first. Anybody in the Southeast that i could hook up with?

All of NASA's rules are here: http://www.nasaproracing.com/rules

top one is the CCR - read the safety, drivers gear and rules of the road sections first.

A little further down is AI, there are some rules there that will override the CCR. If an item is not mentioned in the AI rules, it is governed by the CCR.

At 320rwhp, you are good for 3040# minimum, in impound after a race, with you, your gear, and remaining fuel. Those are great numbers for a 3rd gen. I'd build the motor for reliability, focus on getting seat time and licensed, then build the car for AI. As stated above, building a competitive AIX car is not for the light of wallet.

sounds good to me. you just saved me lots of money.
see ya soon

Thanks Alan. Any AIX guys want to buy some ZR1 11" wheels, Black? I'll trade for 2 ( 91/2")
don't have scale to weight now, would 400engine hp be safe for starters?
does AI approve of a 383ci stroked. If its within the hp requirements of 9.5:1 it should be fine?
Do window clips have any sizes or material?
Do we have to install quick lock steering wheel?

Ditch the 383, you'll not be able to choke it off enough. We all run on a spec tire, so most of the time the lightest car should win. Put a stock 350 or a 5.3 LS motor and run it. Save your money for other stuff.

Just get to the track with a safe car and get seat time.

There is a good market for 17x11's - post them for sale/trade in the classified. The 17x9.5 wheels of choice are 01-04 Z06 fronts - they are the right size and offset, reasonably light, and can be picked up for around $500 for a set of 4 - watch the Corvetteforum classifieds.

There are no rules in AI regarding motor mods, except: no blowers, no NO, no dry sump, no wrong brands. Avoid overbuilding the motor - it is better to be a little low on HP, and put your $ and effort towards adding lightness, and fine tuning the suspension/aero. If you haven't got money invested yet in the 383, I'd stick with stock bore, put a Canton RR pan on it, and long tube headers. Your iron block will be a disadvantage, with about 60# more on the front vs an LS motor.

Window clips are optional - if you use Lexan in the front (3/16" thick) it must have at least one interior brace.

Removable steering wheel is not required, but pretty much a practical necessity with a proper cage and seat.

Do I still need the current spacers to make these wheels work? Thanks for all your help. Im closer than I thought.

A lot of 4th gen AI/CMC2 cars are running the Z06 fronts with my 1/2" spacers on all 4 corners. The spacers aren't absolutely necessary, but they reduce roll and give more clearance for brake ducts, and eliminate a lot of pounding of the inner fender wells.

I can't say how they fit on a third gen, there should be some threads here that should help.

Yeah you're going to have to forget about the 383. The problem is there's also a torque to weight ratio rule; with a stroker motor it's very hard to tune down the torque numbers to stay legal. i'm not sure if you have a block already or what but the two ways I would go with it are; aluminum headed long block from Blueprint engines or GMPP, or if you have a block get a decent rotating assembly and spend the money on longetivity I.E. ARP bolts and MLS gaskets if you can swing it. Good oil control is a must!!!! Road race poil pan, oil cooler and an accusump and you'll have one less thing to worry about.

Don't go crazy on the motor, just get something built that will hold up, get it in the car, found out what kind of power it makes and build the car around that. 320 is an easy number to shoot for with a 350. From there you know what weight you have to shoot for and that will dictate everything else down the line. Like you may not have to spend money on lexan windows because you actually need the weight that sort of thing.

I weigh 240 + glass in front and back. good roll cage and heavy ZR1 Wheels._ 150LB ballast. HP/TQ ratio maybe OK
I have iron vortex heads. Ive done this bas akwards Im finding out. Motors out of the car already. Getting built in 3 weeks. Going to hit dyno down the street after wards to find out the official numbers.