Which would be better if you could do only one,some 26x's degree duration cams from tomei,HKS or nismo.
Or on the other hand some 11.5:1 comp forged pistons .

This would be going in a 3.5 without VTC working,with a redline kept below 7500rpm.
What would be faster in the 1/4 and give more usable power for pure racing ,not worring about day to day feel.
I believe the starting comp would be 10.3:1

 

I have the same question. I want to do the tried and true upped compresion method. Not many people take that route with the VQ. I don't know of any. I want to slowly build an engine with high comp pistons and other nice internals. Is 11.5:1 safe on pump gas with stock or higher timing? Would 100+ octane be all thats needed?

About the cams, SR20 doesn't like them. He says hes never seen a car gain much from them; at least the JWT ones. Are those 260 degrees?

 

i've read that each point of compressions adds about 4% power. If using higher octane fule and a tighter tune you could probably get some serious power out of it. While keeping the low end we need for draging that you loose with cams.

 

Just wondering..Im not familiar with this at all, but
Why not use the VTC with a 3.5 swap?

 

Cause its like impossible.

 

Thats what they said when I tried to run my friends audi on sourkruat. I showed them!

 

Probably cams. Thing is with compression, you have to make sure the ecu can accomodate it. If not, it's high compression and new ecu fuel ign maps.

 

The amount of air/fuel going in will remain the same so what needs to change? Does it need to be leaned out or richened up? I would imagine rich because of high CC temps but high octane fuel will stop pre-ignition.

 

The maf just tells the ecu how much air is going in. But there is base fuel maps for how rich the mix should be. The O2 could compensate to a point I guess. There is also the issue of what high compression does to the ign maps. If you rely on the KS, it will retard the ign maps WAY back and hurt performance.

 

VQ35s are heavily advanced compared to VQ30s, so I'd say a higher CR would probably be okay.

I'd leave the bottom end alone for reliability and cost reasons. You'd have to have the block machined a bit and the rings gapped, which is going to cost.

IMHO, just follow Tilleys' lead, but with the Tomeis for $850.

 

All of this has to be done to put high comp pistons in?

 

Im sending my ecu back to have the redline lowered id prob have them adjust for the comp ,i talked with them and they said they could do it.

 

Yes...at the minimum per 350Z gurus building theirs recently. Apparently, the cylinders go slightly oval in no time, so the new pistons should be .020 overbore and the cylinders bored to match. Then the rings need to be gapped for clearance.

I'd leave the bottom end alone, since it's fine NA. If you think the 11.5:1 is what you need, go with the VQ30 heads and JWT or custom cams.

 

If that were true an 11.5:1 VQ30 would be doing roughly 350HP flywheel.

Why do the cylinders go oval? The overbore accounts for this skewed shape of the cylinder? Alright, so maybe 11.5:1 is a bit extreme. How bout something between 10.5 and 11.0?

 

10:1:1 to 11:5:1 is 1 and 1/2 increase in compression. So rougly 6% increase in power. Like 10 crank horsepower or something. I was told it was an increase of 8%. So 12% increase would be more like 25 crank horsepower.

 

Then it wouldn't be worth it. Stock comp is 10.3:1. So 11:1 would give you like 6-7 more hp, big deal. The VTC will more than compensate for this. People just don't want to mess with the wiring, but the actual cost of the parts required to do the full 3.5 swap (with 3.5 ECU) isn't that much higher. It's installing it that's a total pain in the ***.

 

It's not just the wiring...you need the VQ35 ECU also.

If you are going to go the CVTC route, might as well follow vsmoly and swap the whole harness and ECU.

 

most people who go all out, use more like a 13:1:1 compression or higher for all motor. That would be like 25% increase in power of stock. Which would be like 45 crank on a 3.0 and 60 crank horsepower on a 3.5.


OT: Best all motor is going to be low stroke, big bore. So 3.5 block with 3.0 crank high compression, and reving 8000+ rpm.

OT: Best nitrous and turbo is, high stroke, big bore, low rpm revving.

 

More power is freed up by breathing better, rather than just compressing the air more. Without question I'd go with cams and/or other headwork before I'd worry about bumping the compression just a tiny bit to 11.5:1 or whatever. Like was said already, compression bumping alone doesn't really do a whole lot for HP, and it's alot of work.

Overbore pistons won't necessarily prevent the ovaling of the cylinders (it might, depending upon the dynamics of the block/piston relationship that is causing the ovaling in the first place, but I doubt it prevents it entirely), rather they get rid of the ovaling that has already occurred by making them perfect circles again just like they came from the factory, except .020" larger (or whatever you choose to bore it to).

 

That is what I said. 3.5 ECU. There is this 2002 maxima at a local junyard. I called them. They just got it. It's full, rear ended, and has a whopping 7 km on it (That's 4.2 miles). I can get most parts off of it pretty cheap. I got my engine (2002 Altima) with 90% of engine wiring for 1200$ (CAN$). I'll get the ECU from the US (around 150$ US, same for the MAF) and the rest of the wiring/fuse/relays/climate control whatever from that 2k2 max.

The only difference between what I'm doing and what Vasily did is that I am keeping my 1995 5-speed tranny just like Tilley. Less drivetrain loss, and 6-speeds would be a ***** to find around here anyway. I also ordered Cattman headers and some solid (PR) motor mounts while I'm at it.

 

i would prob have 215-225whp just starting out without cams or comp (i think 240whp+) But i guess the comp pistons idea will die im not going the machining route and worring about problems.

I hope there's more reasons than the vtc why your doing 3.5 ecu .Ive seen nissan dyno it really does nothing above 3000rpm .when im racing i never see below 4000rpm ,i would worry about it if it made me faster but i dont believe it will. what tilleys doing is easier i wouldnt do the whole swap unless there was something major i was missing and the vtc is not major. It gives extra low end for easy driving in parking lots.

 

I was going to do this and use 3.0 crank and rods and 3.5 pistons in a 3.5 block with 3.5 heads but its far from high comp . This route cant be done without serious money and the comp would have to be solved if done with pistons they would be much heavier than stock and revving 8000+

 

Tilley might be right going the way he's going (no 3.5 ECU), but I am doing it like vasily since I get the labor cheap (30$/hour). The only thing I don't like is E-gas. Meh. Gotta live with it. I don't think I can bypass the E-gas with a Pathfinder TB, which sucks. Cables are much more familiar.

Oh, and by the way, any word on SR20's 7500 rpm rev limit? How's the motor taking it with the new bolts? Did he try it in the 1/4 mile yet? I can't ask him since I'm an annoying jerk and he put me on his ignore list

 

wow you will spend alot of money still at $30 a hour You will go thru hel;l with that swap and once you have the 3.5 ecu you have all its goodpoints and badpoints.

I dont have a clue what SR doing ,PM him.

 

When he said every point of compression gives 4% power I thought he meant every .1.

I wonder why...

 

I would say use the 3.0 heads. That way if you get some high compression pistons you would bring the compression ever higher. You could maybe try to get it to run if they release the zemulator program for the Vq engine. Also the 3.0 has more intake manifold possibilities than the 3.5. You would have to port and polish, lighter valvetrain and bigger valves to provide enough air to rev 8000+ and still make power.


I think if someone wanted to spend $4000 instead of going boost they could probally have a 300+ whp all motor maxima. Of course it would be easier to dial up the boost with a turbo for the same money.

 

It's not to prevent it, it's to clean up the ovaling from wear-n-tear and for the best fit to the new pistons/rings. Just like you said .020 seems to be what they are going with to get back to true round bores.

You don't want to just stick nice new round stock size pistons in a worn bore or you can have sealing issues/blowby supposedly.

krismax doesn't want to mess with all that and should just keep what Nissan does best from the factory, ie stock internal bottom-end, and focus on the heads/cams/valves/springs.

 

How far up is considered bottom end?

 

Bottom-end = block and contents in my previous post.

 

I am not the one doing this, so why would I go through hell? I didn't buy anything other than the engine yet so I could go either way, but I haven't seen anything that convinced me that not using the 3.5 ecu is the better way. I mean with the full swap you don't have to tear the engine down and whatnot, already assembled and the wiring/sensors are all there. I paid for them, so why should I not use them? Why would tearing down the engine be more effective? The 3.5 superior flow and VTC will most likely more than compensate for the slightly lower compression.

What 3.5 ecu badpoints are you thinking of that the 3.0 doesn't have?

 

The tuning would be much more difficult on the 3.5. There are so many dynamic parts on the 3.5. I love the way the flow characteristics are very linear on the 3.0. Nothing changes that can throw a loop in your A/F unless you have a VI. I like it simple. Its a bit crude and ignorant but much simpler.

 

Still I am worried about how much the lack of VTC would affect me. I mean SR20DEN is putting down something like 250whp N/A and that is with a 6-speed. 5-speeds, having less drivetrain loss, would probably get a few more HP out of a 3.5. I doubt it can be done without VTC.

 

Actually the bad points i was refurring to is the $$$$$$$$ for really nothing gained over what im doing. I will have 3.5 heads also.

 

Honestly, I don't have time for this. I work 60 hours a week, sometimes 65, and I truly do not have time to work on my car. Call it laziness, call it whatever you want, but I just don't feel like doing this myself at this point. I would rather have someone I trust do it. 30$/hour is actually a pretty damn good labor price for a mechanic.

The engine itself - no wiring - is probably a 12-15 hour job. I'd think the wiring is another 15 hours. That's 900$. Not cheap, but on I'd rather pay ~1k for labor than do this on my extremely limited free time. Of course I could just ask the guy to do it Tilley's way, but I'm not leaning towards that right now.

Are you expecting 250whp without VTC?

Look, I'm not saying you're wrong, and like I said I could still go either way - I only bought the engine and the exhaust system, no ECU/MAF yet. And I still have over a month to think about this (it is to be done late January). But I don't think Nissan would go through the trouble of putting the VTC on it if it weren't worth it. If you can prove them wrong, then it's easier for all of us, and it's just perfect, but I'm skeptical. Hope it does work out just as good for you though.

 

I know why sr ignors your posts you dont read peoples posts.

The vtc does nothing for peak power , i NISSAN dyno comparison shows that .Ive said it to you already and im not expecting 250whp i will have 270-280whp.

 

Yes the VTC may not add peak but at low speeds it sure as hell helps.

Don't rub it in. And take note that SR also chose to ignore others because his own answers weren't clear. Personal attacks are completely unecessary and add nothing this. I just don't know how you can claim to get 270-280whp N/A where the highest known VQ35 dynos are in the 240-250 range.

 

Why do you need to have good power at slow speeds? As kris mentioned the VTC is really ineffectual above 3K. I'm just following his lead. That said when are you ever below 3K going fast? Never! With an engine making as much power as we are talking about, a half @ss launch will easily break the tires loose. Why do you need more down low if a stock max already has traction issues at a 2.5K clutch drop?

The highest known VQ's don't have internal work done. You can get a 3.0 to 200WHP without cams. Just think of the posibilities with headwork, EH'ed/VI manifold, valvetrain, cams, and compression changes. Don't be so pessamistic(Sp?).

 

And exploration is still in it's early stages with this motor. There's no reason we can't pull high numbers out of the VQ, just like any other motor that is built commonly. In fact, doubting it is a mistake, because it's more likely than not.

 

I know, I am just saying that speculation at this point is moot since, like you said, nobody's done internal work.

Also, he said he'd keep his bottom end stock (although Tilley brought up crankshaft weight removal and balancing. Being a VQ I can understand how he doesn't want to mess with the bottom end).

 

People have done internal work there are 3.5's with 300whp with stock bottom end.