What is the most HP that any of you have seen achieved from head work? (regardless if you approve of this mod or not)

 

I can't think of a single person on this site who has done head work honestly.

 

I believe our heads are very hard to work with. IMO, high flowing heads like the ones on the VQ35 would benifit the VQ30 alot. Problem of swapping the VQ35 heads is that it lowers the comp ratio on the VQ30. Which is good if you have turbo or SC.

 

okay, from what I have learned from racing is the single best place to find HP is from the Heads. Some engines can see 40-60 HP gains. Why is no one making better heads or getting heads worked over?

 

no one has an opinion, or have any info

 

maybe u sshud get it done and follow up with us on ur findings....

 

How exactly do you know these heads will benefit from being messed with? It's quite difficult to hand grind heads that out flow a few million dollars in Nissan development work.

If you are that experienced in "racing", you should also know what is good for the goose is not necessarily good for the gander.

 

You're certainly not going to gain anything close to that on a VQ. Those gains usually come on cars that have a very low VE (and really poorly flowing heads to begin with.) Our heads aren't as bad as say a 302 stock heads are. You will probably get more responses in the all motor forum since this is an all motor question. Actually I do remember one guy who I think had some portwork done and a 3 angle valve job, he had a pretty healthy dyno but nothing earth-shattering. He put down like 210-215 with full bolt ons and the work he had done, as opposed to 200-205 for a normal, full bolt on 4th gen.

No one's making heads for this car because as you have probably realized, there is no market for them. No one is porting their heads because our heads flow pretty well already, and the work/cost involved can be better utilized elsewhere. Like why spend the money and time on something unproven and potentially not that beneficial (remember our heads flow pretty well already, so there is less to be gained as opposed to a head that flows like crap before porting) when you can put that money towards a turbo, or a 3.5L conversion and get guaranteed gains of 70 to hundreds of horsepower.

 

So...where in the VQ is the engine lacking performance. I understand that Nissan has bright people who spend thousand of hours engineering their final product. However this is a massed produced car,and their has to be some major gains to be had. Is it in the bottom half of the motor?

 

Kinda of a shame really b/c no matter how good it is out of the factory it can always be better. I'm sure there's some kind of internal improvement that can be done..

 

thats what I am saying, so you have any ideas? Is the Maxima having perfect heads out of the factory a myth that we are led to believe by bolt on fanatics.

 

I do not believe the Maxima heads are perfect. Hell there is a VQ30 race more that makes 450hp at 8500RPM. Improvements can be made but it is gonna cost you.

 

Sure you can make any head flow and make great hp at 8,500 rpm. But what does that type of head do at 1,000-5,000 rpm?

 

You want to know for sure? Take your heads off and have the airflow measured on a bench. Then have the ported. Then measure again. Report back.

 

Very true, you will prob lose tons of low end. But I am sure we can have a head that flows fairly well at around 7000-7500 and still have decent low end.

 

I thought they did? With the ecu and mevi/2000 mani, dyno graphs show it's still making power and not dropping off. This is with the stock cams too.

But then again, there could be 40-60hp in there.

 

There has to be power there. Hell did you see the coil pack dyno? The car was still making nice power, but after the SplitFire coils were added, it raised the dyno up. Similar to a stock 4th gen and a 4th gen with Ypipe dyno comparo.

 

What about milling the head? How much more compression can we bump up on pump gas?
Also what cams can be used with FI + head work?

 

What kind of racing were/are you involved in again?

 

Can you direct me to that link sir?

 

I've taken a pretty close look at the heads. The intake and exhaust valves are pretty much as big as you can get in there, and the valve guide bosses do not take up much room in the ports at all. The ports are gently curved, and the flow path generally looks pretty smooth without abrupt changes. Nissan did an excellent job with these heads.

Heads that show 40-60 hp gains from headwork are lousy to begin with, by definition.

 

These days my racing is limited to the Autobahn. Which is fun as hell with Maxima I have to say. You all would be amazed with what types of european cars the maxima with a few mods can keep up with. I raced 1/4 and 1/8th mile for about 7 years with my Mustang and 'Cuda.

 

I cant find the link that had the dyno picture

http://forums.maxima.org/showthread.php?t=408129

That is the closest thing that talks about the gains.

 

do it...IMO if you're that curious...do it...but be sure to have some extra heads around...why not try honing you intake manifold???we all know how much those suck...or putting down a 00vi??

 

I remember reading that the vq30 came with a 5 angle valve job from the factory. Are you sure it was his VJ that made the gains.

 

Well thats what this forum is for. Just trying to learn previously achieved knowledge that has been gained the hard way. It seems like the general agreement is the heads are as good as they get.
How does the Maxima handle being bored out. What compression is the VQ making in stock form? Has anyone rebuilt the lower half of these cars and can you achieve anything more than what a 3.5L swap can get you?

 

I think 3.2L is he top, something about the walls between the pistons being too thin beyond that. If you used parts from a different VQ it might be more.

 

thanks for the advice.

 

the truth is, nissans VQ V-6 and VK V-8 are some of the most advanced production engines out there, they benifit from many MANY nissan R&D dollars at work, and as such, come with most things standard that many american made engines have done later in life, at expense of the modder. The real improvements that the VQ30 can benefit from are a higher flowing head (VQ35) a variable intake (pref. the 00vi) and lightened internals... however, there isn't a company yet that makes mainstream lightweight engine components for the VQ30DE, so anything such as H-beam rods is, to date, a custom job, and probably pricey. Go with the bolt-ons, and if you have the know-how, install a SC or even a turbo, for our engines, it's the most bang for the buck, and the VQ is quite tolerant of boost compared to a lot of engines *grumble* GM 3800SC *grumble* if you're really adventurous, I'm sure there's plenty of horsepower to be freed up in the VQ, but if you don't know what you're doing, it could get expensive, you could end up ruining your engine, and don't you think the Nissan engineers tried to pull the most they could out of the car, why do you think some of the other things weren't done, they aren't cost effective, nissan did more for our engines than most companies do for theirs.

 

it seems to me that much more refined tuning is seen in the new vq35's with considerable more horspower per liter than the old vq30 stock. So in that case, there has to be some stuff to bump the vq30 up. Also, look at the engines honda engineered. The new ones are so refined that people have to spend more than $1000 for 20 na hp. So in conclusion, and looking at the newly engineered engines on the road from nissan today, i would say that the vq30 must have some fairly obvious faults...somewhere.

 

The VQ30 heads are pretty good, the VQ35 heads are extremely good. The VQ35 powered cars get more power from variable cam timing, more agressive cams in general, and variable intake manifolds for the most part. The heads are superior, but it's not 40-80hp worth of superiority. You put all those bells and whistles on a VQ30 and you are looking at pretty big gains. Stephen max made an interesting discovery about the pathfinder adjustable cam gears in the all motor section, check it out. Variable intake manfolds are old news, we have our choice of those, so that's a no brainer.

 

Are the 3.5L Heads a direct swap for a 3.0L. And will the stock 3.0L cam work well with in combination with 3.5L heads. I really am begining to see why a lot of you guys are throwing the bigger motor in. It just saves the hassle of a lot of guess work. Throwing big motors in a car is very traditional Hot Rodding, I love it!

 

so the easiest thing is to either buy a 2002+ or drop a 3.5 in the 4th gen. I hope to do this when the VQ30DE decided to bite the dust.

Has anyone done serious work on the 3.5s yet? Mods as s/c or turbo? This is be awesome to see.

 

You're going to be waiting a while ......

 

It lowers compression

 

The last couple questions are answered in a ton of threads in the all-motor section.

 

Neal, everytime you go to page 2 of this thread, do you get a LogIn thing?

 

I'm not Neal, but yes I do .....

 

I used to get it but not in this thread. To some comcast crap right?

 

Sorry Guys! It was my signature! comcast is being gay and makes your log on to see my sig. Idk i just uploaded it to another host and i think it fixed it. I applogize!


haha i know but that give me a while to save for it.