Jerminator96

I have no doubt they can be, though I would venture to challenge almost anyone here to a design contest. You design a ITB and I will design a single or dual TB intake and we'll compare the power made through each. I may not win, but I will be close enough that we can compare price tags to judge whether or not a couple hp is worth the cost.But that's beside my point, it would seem to me that in a forced induction motor, be it by a belt-driven supercharger or turbine-driven supercharger, an ITB intake system would lose some of it's 'edge.'Just my opinion though, they still look awesome.

Hate to be a wet blanket, but why ITBs for a supercharged motor? Are you running it N/A for a while?Just curious.

Yeah I know, I just have this idea for a bike that would look really cool, sound really cool, and probably handle like crap.I'm sure the motor would eventually make it into a car of some sort. I envision a small open-wheel, mid-engine, roadster. Something like an ariel atom but with a little more body work and a 500 hp 3.0L V8.The other question is what gearbox do I design it for? Hewland maybe? Something less exotic, maybe an audi?

Well if I ever have access to a serious machine shop I'll get to work on it for you.You're probably right about the market being small in the US for a custom ~3.0L V8, even if I could get 500hp out of it. Maybe I'll just try to build one for myself. But who said anything about dropping it into a kit car? It's a motorcycle engine, right? Hehe

I really liked the idea of that motorcycle based V8. It reminds me of the old Conventry-Climax 2.0L V8s that went into the Alfa Tipo 33s. 10,000 rpm and 300hp.I was thinking about designing one based on the Kawasaki ZX14 motor. If I could do it cheaper than the Busa motor you think there would be a market?

You're right Dave. In theory the most efficient form of fuel delivery for making power is a carb. Though this rarely works in real world examples so the next best thing is extremely high pressure injectors setup like the F1 guys.That's actually why I'm curious as to what pressure the DI systems operate at, it should give me a rough idea as to their fuel atomization capabilities.Jared: I knew those VK56 motors were flex-fuel, but I didn't know they were direct injection, are you sure about that?

Don't give up on ITBs because of water passages. Just get the intake flanges and weld a couple of pipes between them for the water to flow through. If you can fab an ITB setup for that motor you can certainly play connect the dots with coolant passages.When your looking for a motor to avoid any confusion as to what's Gen I II or III just stick to anything pre 92 or just pre 98 Vortec engines. That will ensure a direct swap and ease of adding a carb.

Well you have me by a large margin on experience Doc. I have a good amount of knowledge, especially in the physics of designing high hp mills, but I just don't have enough builds under my belt.I have seen the aftermath of a chevy 396 (SBC with 2 bolt mains) that supposedly walked the crank, but that would be the only one I've seen, if that is what actually happened.Thanks for the clarification.Jeremy

Am I in error on my definition of crank walk? I was under the impression that under extreme cylinder pressure the crank would actually lift the mains and stretch the main cap bolts? Is this something completely different?

I see what your saying. I guess the high hp failures are more likely related to crank walk from extreme cylinder pressures.

Ah carb, not car, that makes more sense. I think you're right, it's just four injectors over a carb style throttle-body. Don't worry about the efi stuff, unless it's free then take it and resell it. If you want to do ITB you will have to fabricate your own efi setup anyway and I doubt that ECU will be able to control it.The motor is a GenI, not GenII. GenII was the LT1/LT4/L99. Believe it or not GenI, GenII, and GenIII motors were all produced and put in GM vehicles in 1997. Your motor will most likely be a 2 bolt main and it will definitely be an iron block.Funny thing about the slang terms we have been using. In your first post you said you had a blown 283, which I was thinking you meant a 283 with a supercharger, but now I'm guessing you mean it's blown up?

I have an extra 240Z in Wilmington, but getting it to Raleigh would be no problem. It's a roller, 1971 240Z, currently set up as a drag car to run a SBC/TH350 with a stock rear. I even have a driveshaft for it.Cosmetically it's a bit rough, but if you're just looking for a project then it might be alright.

The GenI SBC didn't change much more than bore and stroke from 1955 through 1995, except for switching to a roller cam in '86. I would assume your intake would work fine but if it didn't you can pick up another one fairly cheap. I would strongly encourage you to go carb with that motor for simplicity sake, but if you must go TBI then just make sure you get everything from the suburban, right down to the O2 sensors (they're expensive and you need 2).I have never heard of the TBI having 4 injectors, I guess that it's batch fire? Not sure what you mean by 'works similarly to a car' as the TBI motor was put in all kinds of cars and trucks for about a decade with little variety between them. Then again the LT1 and LS1 are more my area of expertise.On a side note I doubt that a ITB intake will change the sound of your car significantly. Most of what you hear is the exhaust, and that sound is largely dictated by firing order.Hope I've been of some help, by the way this should really be in the GenI & GenII sbc section.

Motor mounts should be fine. They are both GenI SBC motors unless there is some difference I am unaware of. Would you need new mounts if you swapped in a '71 350? An intake swap would fix any clearance issues, if there are any. My biggest concern would be the electrical. You are going from carbed to OBDI era fuel injected. Then again, you could always just carb it and keep everything the same. Edit: Oh, and I wouldn't waste time and money on the ITB unless you are just doing it for the looks. Odds are good you won't get any gains over a decently designed single throttle-body intake.

Good advice. There are always stories of the guys running serious power on a stock bottom end, or stock crank and rods. I think those stories give guys a false hope for their old worn out bottom end. I've seen one stock crank and rod 355 LT1 with a blower lay down 480rwhp (550ish+ bhp) but you have to ask yourself why?It's not worth the risk in my opinion, or as my Grandfather always said, 'Do it once, do it right.'

I'm fairly certain the bellhousing was a custom job, depending on what gearbox they were using, Hewland maybe???You have to realize that there are not many similarities between the IRL motors and their production counterparts. It's not like the 60's where you could possibly order a racing spec motor for your daily driver....if only....

I was actually wondering about pressure rather than flow rate, but I guess if you give me that and the size of the nozzle I can do the math myself.

Ah, you did say you were using direct injection, didn't you. Well that does change things. No I am not sure that the PQ conversion would help, but it certainly would not hurt to ask. If nothing else Mr. Vizard might have some ideas on how to get 290+cfm out of those heads.Just out of curiosity, what pressure are the injectors working at?

You are obviously afflicted by the same 'engineering disease' that I have. There is no cure, and I wouldn't want it if there was.I wish I would have known you wanted to do this a few months ago because I gave away a set of vk45 heads back in march. The one interesting thing about the Nissan V8s is that the bore centers are nearly identical to the SBC. With some block machining you could make them work with relatively little money and then take advantage of a 4-4.185 bore and a huge after-market. I know you can buy Cup Car cranks from wrecked stock cars with low mileage fairly cheap, and they turn 9000rpm almost continually for 500 miles. Just something to think about.A side note: don't get hung up on low end torque. Torque is just a measurement of force, horsepower is the amount of work being done by that force. One benefit of being able to spin the motor high is the amount of gear you can use. An F1 car only has 300 lb-ft of torque but it can stay in first gear up to 19000 rpm. I'm sure you know this, just reminding you.About the PolyQuad conversion: the main idea behind the PQ is increasing combustion efficiency. The big problem with the pent roof 4 valve combustion chamber is that at high RPM with a lot of duration (which is exactly what you'll have) the fuel tends to flow right out of the still open exhaust valves. This gives you less power at best, and dangerously lean burns at worst. The PQ was developed to fix this.I'm all for your project, and if there is anyway I can help you let me know. I'm all about building something to test theories, be original, or just for bragging rights. Heck one of my current projects is an H2O2 powered motorcycle. In the future I plan on building a light weight, high-revving 2.8L V8 to drop in a 280Z. Like the old coventry-climax 2.0L motors they had in the Alfa Tipo 33. Sure I could probably just get a 2.8L Ferrari V8, but what's the fun in that?

That's not a bad point, you can get a 3.5L IRL motor for $15000.I got the impression that he was going to do a custom crank anyway to run reliably at 9k rpm, so at that point why not add a little stroke?

You either know a whole lot about engine building (in which case why bother asking) or you subscribe to all of the 'old wive's tales' in the business. Don't take this as a put down, you've obviously taken the time to educate yourself and that is a lot more than most people will do.My number one question (before I question any other aspect of your engine) is what do these heads flow? After all the porting and whatnot what do you expect to flow through each intake port? I would say if you can manage 300cfm you can pull of 600 hp (as a rough guess). If you can get 330cfm a monkey could build your shortblock and you'll still hit 600 hp.If you really want big power out of that motor I would suggest you contact David Vizard in Charlotte NC and ask him about doing a 'Poly-Quad' conversion on your heads. After you do that you can decide whether the rest of the build is even necessary.Just my $.02

Yeah here in NASCAR country it seems like ever grocery getter has a Nextel Cup motor in it.For that matter there was a guy recently on craigslist selling a set of SB2.2 heads for $400. He had another set of heads that would be a direct bolt on, I can't remember what they were though. I'll see if I can find him.

Racingjunk, it can be a real mess as far as searching for something but if you have patience you can find great deals.$10k can put together a heck of a motor, even after spending $4k on your shortblock, especially if you get the heads and intake used.

The Iron Eagles would be my recommendation for a budget head also, but I am a big fan of buying used too. If you look around you can find some good deals on the nicer Dart and Brodix heads with low mileage or a fresh rebuild. The 15 degree stuff would definitely be the way to go for serious power but it would be difficult to do it cheaply. Even if you did find a good deal on the heads you still need the valvetrain, intake, custom exhaust, probably pistons, etc.If money is no object then spend $20k on a Dart Little Chief setup and you can have 1200 hp naturally aspirated.I could also check with my uncle and see if he still has an extra set of heads from his dirt track car, if they can feed a 360 at 9000 rpm they will probably do alright with a 427 at 6500. If your interested let me know and I'll get a price and the details.

I'd say those are great heads for a 302-327, good heads for your 350, and 'useable' for a 383...but a 427 is a bit out of their league.That being said, you do have fairly modest power goals for your 427 so if the budget is tight then it's better to have a low power 427 than a high power 350 in terms of reliability.Did you ever mention a budget? I could recommend some heads but cost is a factor.