Now please understand, this isn't a real plan of mine as of now, I just want people to throw around some ideas. If and when my motor blows, I would like to do some internal work to the engine I put in. As of now, I have the basic mods, but when I get my money together I would like to get the VI and JWT ECU. I want to keep the car NA. By raising the rev limiter, I fear the valve springs wouldn't hold up after a while, so while the engine is out of the car, I would like to do some work to it. If I got some stronger valve springs, how high could I safely rev the engine? How much would the springs and installation cost?

Since the car would be reving high, would there be any other internal work that could be done with good results, or that would go well with the raised rev limiter? I've done a lot of searching, read some stuff by I30krab and turbo95max, and gotten a blurry idea of what would be worth the money. I've ruled out getting the intake manifold extrude honed because I heard it doesn't do much for about the $600 it costs.

I was looking at a port and polish because I read it helps out a lot up top, which seems like it would complement the raised rev limiter very well. I'm still a little shaky about which parts would be done, and how much a job like this would take. I read $600+ for a head p+p, $600 for a 5 angle valve job....and some other stuff. I don't know what would be/should be included in a job like this. Any input would be really helpful. What kind of gains could I expect? Maybe 10 hp?

I've also ruled out trying to get cams, pistons and new rods, seeing as how they are way too expensive for me. I'm interested in seeing dynos that would show any gains of the parts I listed above.

Any ideas you guys could give me would be great. I don't want a fully built motor, cause I would never FULLY use it, however, I think some mild internal work, ever if its just valve springs, would help the car out. BTW, I'm also doing some of this to keep the car reliable.

 

if you raise the compression of your engine that would to me be best Pistons are about 600 I believe. its the rods that are expensive. Either way the higher compression would be the best bang for your buck, horespower wise.

 

you're joking right?? those are about 75-80% of the components that make up a good power N/A motor..leave those out and you're wasting your time, might as well stay stock.

 

I understand that, but understand I'm entering college and this project is on a budget. How much money would each of those cost, and what gains could I expect (approx)?

 

its gonna be pretty expensive...but IMO its pointless to do a "halfway" motor build up. if money is a prob just buy the parts here and there and build it over time. maybe its me but spending $600 on P/P and then another $600 on a 5 angle valave job(which isn't so great for everyday driving) is a waste if you're not gonna complement the heads with a nice cam or port job as well. just my $.02 Plus if the motor is out, why waste it and only go halfway.

 

Well, thats why I started this thread. What are the benefits/drawbacks of the 5 angle valve job? Which SINGLE mod would complement the higher rev limiter? I thought the P+P would, but I could be very wrong. Even if I just get the p+p and new valve springs, I think it would be nice. But then again, lots of the labor is just getting the engine out and open, so it might be worth it to put some other stuff in there while its open. Do you know which companies make pistons/cams/whatever?

 

JWT makes cams for us of course and i remember seeing pistons and rods for sale on a website somewhere. i'll see if i can dig up the site again.

 

If you can't spend the $ to build a quality high compressin NA motor, might as well forget it. Period. Plus you have to get an ecu to handle the new compression/fuel/timing changes. Got another $600?

THERE IS NO COMPROMISING IN BUILDING MOTORS. It's either right not not at all.

 

I don't think you really get it. I don't plan on building a fully built engine, nor do I plan on spending much over $2k on the job unless the results are out of this world. As of increasing the compression, it's not at the top of my list right now. In the future, I don't think I would get pistons, cams, etc. unless I win the lottery. I want bang for the buck, and results that would match the profile of my engine after the VI/JWT ECU. I want basic results out of basic monetary input. What do you think the price difference would be between p+p and valve springs vs. EVERYTHING? I'm not able to come close to that difference until a few years after I graduate from college (at least 4 years). I'm already in debt due to my tranny dying. What would you do in my situation if my engine blew in 5k miles? And wouldn't JWT be able to program an ECU that would be able to at least to take care of basic engine work (p+p)?

 

SO in other words, you want something for nothing. Gee.. don't we all.

There are two basic ways to increase the horsepower output of an internal cumbustion engine.

1) Increase the volumetric efficiency.
2) Increase the thermal efficiency.


List of ways do attain those goals.
1) A. Boost
B. Increase the displacement
C. Cams
D. Intake manifold change or work
E. Headers and exhaust for better scavenging.
F. Cylinder head work, (porting, valve grinds in size increases)


2)A. All of the above applies here
B. Higher compression pistons
C. Nitrous





Now please pick from that list the items that do not cost much money.

You can rule out porting and polishing work on Nissan heads. You will get very little to NO gains for alot of money. They're already that good.

 

Cheap Ways:

Bigger Throttle Body 10% to 15% more air coming in + 4 inch intake. 15-20 horses

Thinner Head Gaskets for Higher Compression( I think some mustangs guy do this.)

I think Madigras said you can use the cam springs from the 3.5 motor becuase they are strong like titanium ones. They are only like a dollar a piece, instillation would be expensive unless you do it yourself.

The JWT ECU and Mevi

You can adjust the cam timing for even more power up top, you would lose alot of power down low it would feel like a vtec thing. But your mevi and raised limiter wopuld benifit alot.

Full lengh headers to a 3 inch collector and 3 inch catback. If you can get enough air and fuel this would be a huge gain.

I don't know much about cars but this might help a little bit.

 

3" exhaust on an N/A car??
4" intake?
$1 a piece for valve springs??
adjusting cam degree/timing on the VQ?? since when....
and I suppose you're just gonna slap on a thinner HG and goto town right??

 

Nope

Not on this motor

Nope. The VQ30 springs are slightly more stiff. And there is no such thing as a titanium valve spring.

How is that not expensive?

Who makes that? It's going to be custom and cost about $1500 to get made. Is that worth 10-15 hp?

 

IMO, don't waste your time our money digging into the internals of this motor. It already does everything very well and it will take a large amount of money to make significant gains. Add the JWT ECU then get the MEVI. Those two mods alone make the VQ more than impressive for NA.

Increasing compression would be very hard because you have to figure out how to remove the slack from the timing chain plus you'd have redo timing, etc.

The pistons, rods, and crank seem to be very strong and can handle 300+fwtq. I don't know about how well it can handle high revs (7500rpms), but I'd assume you'd be fairly safe below 7800rpms, but this will require valvesprings and cams (to support the power). Installing valvesprings requires removing the cams, so you might as well get the cams too. I've looked over that's required to remove the cams and there's no way I'd do it. First there's four cams to deal with.

You need to remove valvesprings/cam you need to:

1) Remove the intake manifold
2) Remove a couple engine mounts so can tilt the engine up
3) Remove timing chain cover
4) Remove timing chain
5) Remove cam chains
6) Remove cam bearings
7) Remove cams
8) Remove 24 valve springs and shims

Then it's time to reinstall everything which requires you to shim 24 valves. Sounds like fun

Cams and valvesprings will definately wake up the VQ (~15fwhp), but keep in mind your lowend will disappear. Normal driving will be Honda EX-like.


Dave

 

to avoid all that hassle, why not just use higher CR pistons??

and I know the VG is a whole nother motor, but I've ridden in a mildly cam'd(Nismo Euro cams) 92 GXE Maxima and the loss of low-end is barely noticeable...selecting the right profile is probably the key.

 

I'm not expecting huge gains, don't put words in my mouth. Like I said, I want relatively small results from relatively small input. I want parts that will match the profile of my engine with the VI/JWT ECU. Since p+p is out of the question, what do you think the most important/ best bang for the buck mods? And how high could I safely rev the engine with the new valvesprings? Which parts would be under the most amount of stress from revving that high? I would want to strengthen my engine first, even if I don't really get power from it. I want this 7500+ rpm engine to be "almost" as reliable as the stock 6500 redline engine.
BTW, spanishrice got

 

Since you looked over this, did you by any chance get an estimate from a shop on the price? Who makes cams for us, and how much do you think they cost? How necessary would cams be for me revving that high? Has anybody here dynoed after getting cams? Where is I30krab......And how would my 1/4 times be affected with a 7600ish redline? I read a while ago that 1/4 times wouldn't be affected if you got a 7000 redline instead of 7200. I know this is a bigger difference, but I'm just curious as to the results. Where is STEvtec.....

 

Question: Are you going to do this work yourself? If yes, you had better be GOOD at this stuff. If you are going to hire someone, it's gonna cost ALOT for a GOOD/EXPERIENCED mechanic to do this work correctly.

ie.. let's say you do your "P/P". Not only are you paying probably over $500 to get this work done, you have to pay another $500-$1000 to have someone pull the heads and re-install them. For what? 7hp?

 

Nissan shop labor for replacing valvesprings is estimated to be ~12 hours, I believe. So you're looking at least $720.

JWT makes the cams (4) for $1100.

JWT makes the valve springs for ~$250.

You've got to understand something, there is NO POINT revving above 7200rpms unless you've changed something that extends the motor's ability to continue to make power past the 6200-rpm HP peak with the MEVI. Numerous things can be done like changing the intake manifold, adding cams, port work, etc. Things like Y-pipes and intakes DO NOT change where the motor makes peak power. The shape of the curves are the same, but are elevated.

The only reason we need the 7000-7200rpm limiters is so that our shift points are ideal. Pretty much you want the RPMs to land around 4800-5000rpms on every shift with the MEVI for optimum performance. The ECU allows us to do that. Shifting at 7500rpms WILL slow you down because you're overshooting the next gear entry rpm.

Spending over $2100 to run cams and add 15fwhp seems a bit pointless to me when you consider this is just a FWD V6 family sedan. What about when it comes time to sell the car? You're not going to want to pull the cams back out therefore you're going to loose you *** in terms of money.

If you go ahead and change out the cams, you might as well extrude hone the intake manifold. It doesn't gain a ton of peak power, but it does increase overall power at every rpm. If you've got $2100 to blow on cams that get you 15fwhp then you've got $600 to blow extrude honing the manifold that gets ~10fwhp at various parts of curve.


Many of us have obtained lower 14-second performance with simple bolt-ons that can be easily removed. Low 14s in a V6 NA sedan is pretty rare and to me it's very impressive. That puts us in the same league as the GS400, 2nd generation BMW M3, BMW 540 6speed, G35 coupe/sedan 6 speed, 99+ Mustang GT, LT1 F-Body, and even the 350Z. I've raced and/or watched all these cars make passes at my track and it's a driver's race. I'm very happy with my car's performance for as little that's done. My biggest complaint is I wish I had more lowend torque. Don't get me wrong, the 4th gen VQ makes really strong torque, but I rent a ton of trucks for work and I love having that power right off idle.



Dave

 

Like I said I know nothing about cars, haha.

 

No, I don't plan on doing the work myself, although I wish I could. Thanks for your honest input, this is why I started this thread.

Dave: Thats what I was looking to hear. I wasn't sure if the optimal shift point was 7000-7200, or if you guys weren't going any higher because of the effects it would have on the engine. I just really don't wanna put on the VI/ECU only to have my springs go out after a year or two, and have to have possibly other bad things happen to my engine. I would really like to have at least valve springs put on, but seeing as how that looks like the whole job could easily cost over $1000, I'm just even more confused now. I remember one of you guys with the VI/ECU had problems with your springs going bad. Whatever happened to that?

 

No one was having problems with their valvesprings. It's me you are thinking of, and it wasn't the valvesprings. I don't know what it was, but whatever the problem was it has gone away. It was only evident for about a week and now it's gone. My motor has 146K miles on it and is doing just fine at 7.2K.

Anyhow I think you should scratch this idea unless you are willing to go all the way with it. Doing just some of this stuff wont gain you anything. It all has to be done for the gains to be realized. But to answer your primary question about what the biggest gain would be out of all the things mentioned, cams. You can get regrinds done for under $400. They wouldnt be quite as nice as true billet cams, but they would be a helluvalot cheaper to buy. Of course then you have to pay the 12 hours labor to install them. And then you need to get springs/retainers. And then you hav to have your ECU reprogrammed again, etc. Get the picture? You cant do half this stuff, it all has to be done because one thing requires another.

 

Ah, well that clears things up. I was real worried about the valvesprings, but since you said they're doing fine, I guess thats good enough for me. I was still under the impression that the springs are under a lot more stress by revving that high. How many miles have you put on since you got the ECU? Well, since I have no need to upgrade the springs, I have to reason to go into the engine at all. Like I said, I started this thread to get ideas, and I got them. Thanks guys. I guess its stock internals for me for a while.....

 

The valve springs will definately be under more stress, but as we well know, Nissan overengineered many of the parts on the VQ. Ironically, the valve train is rather weak, but it's more than up to the task of handling a 7000rpms rev-limiter. You can get the 7200-rpm limiter which will probably be fine, but there's slightly more risk involved in terms of potential valve float. Extended time above 6500rpms is where the valve train could be weakened and you could get valve float. 1st and 2nd wind out really quickly to 7000rpms so valve train wear/float isn't much of an issue. In 3rd and 4th is where you should be more cautious because it takes the motor longer to rev from 6500-7000rpms. This is where potential problems could occur if your Max happens to have weak valvetrain. Of course, how many times a month are you winding out 3rd at 97mph+. Honestly, the only time I wind out 3rd to 7000rpms is at the track.


Dave

 

95maxrider...thanks for starting this thread.

 

actually dave, i would wind out 3rd on a daily basis 97+mph but any way who on the org has cams? where can i get some from and what have been the reviews?

 

but with a higher profile cam that becomes all the more dangerous because more stress is put on the valve springs while you're trying to "wind it out"

Cattman has cams....$1100 + install ...not worth it IMO.

 

bore out the motor and then add some boost :-D

 

Let me just ask this... Nick have you gotten your car back with the tranny in it?

 

no.....and im pretty furious about it. the company sent me the wrong tranny, and they should be in the process of rebuilding mine right now. only now, im out about $800 in labor stuff, and im fighting the company to get them to pay for all this ****. do you know if darryl had any luck getting the new gauge stuff he messed up? thanks for all the input dave and neal.