entropy31

very common question around here. here is your answer before you ask.

reddzx

Quote from Satan on 88hybrid.com

"This is something I said a while ago. Lot of rambling that will never get done but if someone were hell bent on doing it, this is what I had to say.

When running NA you cannot move as much air in a given amount of time as a turbo car due to the lack of pressure(or I should say "volume"). What can you do to move more air then? You need higher RPM's. You can move more air but you just need more strokes to do it. This means higher redline. This is a problem on the VG30. anything above 7k and you are looking at bad stuff happening to the rods if it is that high for an extended amount of time. You need rods and good rods. Eagle rods recomends not going higher than 8500rpm's. Thats not good enough. I am looking for 10k rpms on my 3.3liter. So.... good rods. Maybe you dont want to go 3.3 liter due to the fact that you are adding weight to the piston by adding diameter. No good for revs.

Now displacement, Take your 3.3 liter and take it out as far as you can. They say you cant go further than 3.4 liters, but guess what... Thats for turbo. Face it, you just flat out wont be making the power of a built turbo, BUT this allows you more bore I would assume. The walls do not have to hold as much pressure. How far can you take it? Got me, try it and find out.

Now, you could stroke the engine to gain displacement, but that is not helping your 10k rev limit AT ALL! To much piston speed, and now you gotta bring your RPM's back down. Its give and take. An engine is always give and take. Maybe even DE-stroke the engine a little. Some of the badass z32 race cars ran a vg30 de-stroked to a 2.6 liter I believe (somebody may know for sure) to get a higher red line.

Compression ratio's. Now 9:1 aint doing **** for your NA power. You wanna bump that up to about 12:1 maybe even 13:1. Yeah, you gotta run race gas all the time now. Meh whatever. EDIT> (funny, Russ just posted he is running 12:1 as I was typing this LOL)

Combustion chamber shaping. Hmmm, yeah, study up on that before you go making what you have worse than what you started with.

Cam shaft profiles and gears. If you are running a really high RPM motor you are going to want good over lap for scavenging of exhaust gasses. You dont always want to run a high lift. The faster it ramps up, the more of a chance you get for valve float. Do research on cam shafts. SOHC, well... you can only shift your power band now cant you. Well since this is a high revving engine, you are probably going to be staying above 5k for the majority of your racing. Guess you better shift your power band to the higher side then.

Roller/solid lifter. Roller lifters obviously have less friction and allow you to run a more aggressive cam profile. Solid lifters, no spongy crap for this engine. Time to manually get your lash correct!

Light weight everything. Anything that moves in the engine bay can help if it is lighter weight EXCEPT THE HARMONIC BALANCER. If you go light on that, it should still be a harmonic damper and NOT just a lightweight pully! Lightweight parts, A- not as much rotational inertia and B- Lighter weight parts are easier to keep in check. Lighter valves dont float as easily. Lighter flywheels rob less power and help the engine rev faster. Stuff like that.

Retain your heat. Heat = power. Keep the heat where it is making the power. If your heat is leaving the cylinder through the walls or through the head or through the piston, then it is not being used to make power. Coatings help keep heat where it should be. Coat top of pistons, coat cylinder head combustion chambers, valves... anything you can think of, hell even the intake manifold. Keep heat where it should be and cool air where it should be also.

Tuning your exhaust and intake. This itself could be a whole damn book. Cam profiles come into play, runner lengths, pipe diameters, pipe tapers, pipe lengths. Lots of reading can be done on this, I'm not going into it here.

Porting and polishing? No ****, this can actually help? The hell you say? Make EVERYTHING as smooth as you can on a direct port fuel injected system. Keep ALL of your transitions as smooth as possible. If you have to have a step, make sure flow steps OUT and not IN. You can have it taper in but not step in.

Valve jobs. 3 or 5 angle, yeah just more stuff to help flow.

Moly coatings. You can coat friction surfaces like your bearings and your piston skirts to reduce the friction. Obviously, that will help.

Balancing and knife edging crank shafts, balancing, polishing rods and crank shaft. Knife edge cuts through the oil better than smacking it like a open hand on a water bed mattress. This also keeps oil from frothing. If your crank shaft is polished, oil has a harder time sticking to it, same with the rods. You can run crank scrapers to keep the oil down in the pan where it belongs. Balancing, well... your engine should be properly balanced regardless of the performance you are trying to get.

Shifting tolerances. You can shift all of your bearing tolerances to the looser side of things. This is not good for longevity but is good to reduce friction and free up maybe .00000001 hp.

Blow by = bad. Where do you think the majority of your blow by comes from? Most people would say the gap in the rings. Well this can be true depending on how big the gap is. What if you ran some total seal gap-less rings? Hey, leakdown of less that 1% sounds fricken awsome to me! But wait, with gap-less rings should seal perfect right? NO, your cylinder is never perfectly round. The rings cant conform to the cylinder perfectly. This is where lots of blow by can come into play. In many cases this is more of a problem then ring gap! I have actually herd (Or I dreamed this up) of pistons that have holes in the top of the piston that lead to the area right behind the ring, MEANING, as your piston compresses, it send pressure to the back side of those rings FORCING them tighter against the cylinder wall, Forcing them to conform to the cylinder wall more, thus reducing blow by even more.

Nitrous? Pffft. That is blasphemy when talking NA. But getting your fuel and timing PERFECT (which can take months, even years with some perfectionists) can benifit you quite a bit when trying to make power with ANY application, turbo OR N/A.

Meh, I grow weary of this. Too much effort for not enough power, I dont even run N/A why am I even typing this **** out? Oh, that right, because you guys asked.

There is plenty more that you can do, this should get you started, OH and dont forget to post your results in a few years when you finally get that super engine built'"

Russ84na

Pretty much went a step or two more than Johnboy, took much of Satan's advice.

http://z31performance.com/forum/view...hp?f=1&t=15737

reddzx

Yeah, a step or two is right. Good Job Russ.

hoov100

damn, thats an impressive number for a N/A 3L.