the only favrication that will need to be redone is the exhaust manifolds. If it's designed from the begining with both motors in mind he'll be fine.

 

Isnt there a for sale thread for the set up, also collecting dust?

 

you cant say that turbo lag is a reason for choosing the higher compression if theres less of a chance of detonation id rather run the lower compression and work on turbo lag a different way and of course bmw can take that risk cuz they can calculate exactly how much turbo their cars can handle and we would have no clue where that line is until we blow an engine

 

As with most things, "bigger" is not necessarily "better". Aside from the VG--VE differences, (in my mind the greatest being flow rate with the
4 valves per and DOHC's), larger turbochargers usually take longer to "spool up" and can cause tremendous lag problems. Great if you're going for a land speed record and need the top end horsepower, but terrible for accelerating out of a corner on a road course. This was the problem that sequential turbos tried to solve by having one spool up quickly and the next one pumping in the added volume. There was one company down in Texas about twenty years ago, Turbodyne I think they were called, that came up with an ingenious mod that introduced a series of radially mounted air "vanes" within the compressor housing. It would channel the compressed air into a smaller sized chamber, gradually expanding as turbo rpm's climbed, always keeping the flow rate (and thus throttle response) high. The vanes looked like little overlapping airplane wings that pivotted outward as rpm's increased.

Personally, I like the NA DOHC engine, and with some careful porting one can maintain flow velocity and higher horsepower by getting rid of the areas that disrupt or slow down flow. I have found the greatest single area for porting improvement to be around the valve guide bosses. In trimming away a lot of that material, and blending the top in flush with the guide and valve stem, even grinding a kind of boat's bow shape running into them, I've seen as much as a 15% increase in flow on a VG. The difference was surprising. Smoothing the runner into the stelite seat helps and opening up the radius of corners in the intake plenum helped too.

 

First you said you "like the NA DOHC engine" but then you mention "a 15% increase in flow in a VG". So which is it? Are you talking about porting the heads on a VE or VG?

 

Sorry for the discrepancy Kanda; I have a '89 VG 30 that I did the mods on. The results were significant. IF I had my druthers, I'd have the VE,
which would no doubt respond as well, (if not better) to the same mods.
HOWEVER-- judging by all the VTC complaints about that engine I have read on this site, a VG to VQ swap sounds like a dream come true, and a far better choice! Now if the "mechanic" who made the claim was forthcoming with satisfactory details, I think we'd all be very happy. None of the links worked for the images, the last four times I've tried them.

 

+1

 

That's because you choose the easy way out. There's more power to be had in a high compression turbocharged engine than in a low one. Sure you can run more boost in a lower compression engine, but you get more power out of higher compression with lower boost. That again speeds turbo spooling as the turbo doesn't need to spin as fast. it makes the turbo last longer and has less heat. the car drives better because it has better throttle response on and off boost.

Detonation is caused by poor tuning and only poor tuning. (where tuning includes running the proper fuel for the application, ignition & cam timing, fuel mix, proper spark plugs, etc). running even a low compression engine with too much timing and crap fuel will cause detonation and ruin the engine.

 

from wat i can find there is a direct link to detonation and static compression but at the same time this can be fixed with camshaft timing
and low static compression will actually cause poor engine performance simply because youve got extra room so for a street driver its best to have a mild cam with an early intake valve closing point which will be less static and best for low rpms and will only cause innefeciency at high rpms never detonation
so for turbochargers it is best to have the lowest compression ideally 7-8:1 but all motor guys would suck at this level (probably why the ve gets an extra 30hp) so the higher compression is best for guys with a NA engine

heres some homework
http://www.vg30et.com/about.html
http://e30m3performance.com/myths/mo...comp_ratio.htm
http://www.rbracing-rsr.com/compression.htm
http://www.kb-silvolite.com/article....n=read&A_id=36

 

edit.... upon re-reading previous comment, I take back my statement...

still impractical for most of us, and there's no need to drop compression in these cars to make decent power when turbo'd..

 

I think what he's trying to say (and plz correct me if I'm wrong) is that there is a nearly infinite number of variables in setting up an engine with a turbocharger induction system. I dispute the claim made earlier that you can run any turbo system on regular pump gas. The more fuel/air you cram into a given volume, the more the engine will want to behave like a diesel engine, which essentially uses compression (18:1 in some cases) to set off the explosion. Higher octane slows the progression of the flame front during ignition so the explosion "burns" more slowly. Low octane fuel is more volatile and the wave front travels much more quickly-- opening up the very real problem of detonation and all the damage it can cause.

For street use, (and I'm thinking this is where most of us will be running our Maximas) a big turbo, lots of boost, longer spooling times (lag) and $4.79 a-gallon premium fuel are far too impractical. Not to mention the smog regs in most states where such an illegal mod driven on the street can cost you a $10K fine just for starters, and even seizure of your vehicle as evidence if you **** off the cop who pulls you over. It isn't worth it IMHO. Better to take Mark Cookson's route and use an '89 300ZX turbo system (along with the computer) and then apply all the street legal aftermarket mods available for that drivetrain, like a computer chip, intercooler, etc.

 

yeah, I hear ya.. I read it wrong the first time and was in the middle of an arguement with my boss over some crap that got screwed up and I'm getting the blame.

anyway, I edited my comments..

In any case, if people here are worried about $5/gallon gas, they shouldn't be modding their cars like this. it doesn't matter whether it's 87 or 107 octane- it's still expensive. And if you can't pay for it, don't build an engine burns a gallon a minute.

 

speaking of that, do VG and VE engines benefit from the atomization of intake air from the turbo when cruising at a normal speed? or is that just smaller engines that benefit from it? MaxMaxima reported he gets 31mpg highway still..... which is exactly what I got on 3 of my 4 tanks to/from Maxus (1,900 miles total), the other being 27.5mpg with 200 miles of driving within Chicago itself, on a n/a VG5, and he also has a VG5. Variables: he's got a turbo, and i've got a failing injector (and therefore, slight misfire).

 

the thing about a turbo is if you can stay off boost you get the same mileage as an N/A motor.

 

I'm not sure if I ever put it for sale.

 

None of us here have the technical skills to properly identify that in our engines, BUT I doubt it really makes much difference there. The big difference you'll see when you turbo the engine is when you start tuning the ECU. I know a couple guys that run full standalone ECUs on their turbo VGs and are able to get mid-30s on fuel when they keep their foot out of it. put the stock ECU back in and they get high 20s.

Atomization really only applies to the fuel itself as well. the finer the injectors spray, the better the fuel will break up and atomize into the intake charge. the intake air itself (minus the fuel) really isn't affected by the turbo except from the additional heat put into it by running it through the turbo.
Albeit the higher temps will help atomize the fuel better, the higher temps also mean a smaller difference between intake and exhaust temps, which means less energy produced by the engine.

So exactly where the line is between better fuel atomization and losing power due to heat-soaked intake air, we can't really tell. Again, it takes engineers and $$$lots$$$ of sophisticated test equipment to be able to answer that.

 

Quote--Matt93SE--Atomization really only applies to the fuel itself as well. the finer the injectors spray, the better the fuel will break up and atomize into the intake charge. the intake air itself (minus the fuel) really isn't affected by the turbo except from the additional heat put into it by running it through the turbo.
Albeit the higher temps will help atomize the fuel better, the higher temps also mean a smaller difference between intake and exhaust temps, which means less energy produced by the engine.

True. HOWEVER-- back when guys like Ak Miller and more recently, Gail Banks built turbo systems that were carbureted and were "draw through"
induction, the turbo would actually mix up the air-fuel charge, providing finer "atomization". And it was also true, particularly in those types of systems, to see higher mileage figures when you didn't stomp on the gas for a while.
One of the early Petersen Publication books of Fuel Systems had an article on fuel atomization as a specific process of setting the most efficient air/fuel ratio. I don't remember the exact number, but the fuel droplet size that proved to be most efficient was around 14 microns I believe. They used an ultrasonic device that resonated into the plenum above the intake manifold and the plenum itself spun at a variable RPM, using centrifugal force to throw the larger fuel droplets out and away from the air stream until the ultrasonic vibrations broke them down to a small enough size that they would move towards the center and be inducted into the engine. It sounds like New Age BS, but the thing really worked and was very remarkable in its efficiency. As far as I know, subsequent editions of that book were published without this story. I happen to have one of the original copies.

 

Okay, that makes more sense in why you asked that question. Atomization is usually only an issue with carb'd engines, as they run very low pressure and relatively large orifices to dump enough fuel into the system. that means drops instead of spray.

The big difference between that and our application is the fuel is being drawn through the turbo with the air vs. our cars where the fuel is injected post-turbo. since the fuel is injected into the air charge immediately before it goes into the engine (it in fact sprays onto the back of the intake valves somewhat, which helps cool the valves and vaporize the fuel from the heat)

But yes, there is a finite size of fuel droplet that does best. that size changes somewhat with engine variables, but is generally going to be close to the 14u that you mentioned..

 

so you do agree that if u wanna acheive better mpg and save gas while getting the same hp then its better to use more boost and lower compression but if your rich *** has enough to waste on gas when it hits $10 then u should get a higher compression force yourself to use premium gas and avoid some slightly annoying turbolag

 

if you pay 7% more for premium gas, and get 15% better MPG, then who's laughing now?

 

So, where's the guy with the VQ3.5 swap anyway!? Is he coming back to give us any videos or updates of it running and driving right? If not, maybe I should ask my friend if I can get her totaled '02 Max as a donor car and do it up myself.

 

No I don't agree. I never said anything of the sort. The best way to get better mpg is to increase the efficiency of the engine by freeing up the intake and exhaust flow, lowering rotating mass, and leaning out the fuel mix. When done properly, this can be done on ANY engine regardless of compression ratio or fuel type.

you will also generally get better fuel mileage on an NA car, even when running full throttle, because you can run a leaner fuel mixture without fear of melting things.

 

ask her anyway, thatway, if we get the info we want, you can do it up. if not, you have an 02 max to part out, or swap stuff over.

 

I already arranged to try and part it out for her. Depending on what I can get for the parts, maybe she'll let me keep the drivetrain as payment I'm not sure, though, if it's worth it. It was rolled and looks pretty beat up. I'll post in the classifieds soon.

 

vg ve vq we all know which is better stock but which engine has the highest cappabilities ive heard that a vg can handle 1000hp but all i can find is 450hp482tq where could i find the record breaking engines and who can drum up higher numbers with a ve or vq

 

Stop. Please. IT's been covered 10000000 times already.

 

weel i cant find it anywhere on the site show me a link i think it has almost everything to do with a engine swap thread like this

 

the point of an engine swap is to get the biggest bang (no pun intended) for your buck. if the vq30/35de is a better engine, in regards to weight tq/hp curves, aftermarket internals, then it makes a swap like this more appealing. considering there is little aftermarket demand for vg, less for the ve , almost nobody mass produces stuff for it. the vq market, however is still thriving. companies make all sorts of aftermarket parts that would work with a swapped engine.

 

Lots of companies make ALL SORTS of stuff for the VG. You just have to know where to look.

and no, the point of an engine swap is not simply bang/buck. there's thousands of reasons people swap engines- everything from parts availability to weight to coolness factor.

 

sorry, matt. I over-exaggerated the (un)availability for the vg, and forgot the "coolness" factor

 

That's better. now lean down and kiss my feet like a good .orger.

 

 

Kinda like putting a jdm vq30det into an s13 coupe with a holset turbo and a dek IM hovering over the RH valve cover. Oh yeah, that's what I've been working on lately. It definitely has a very high "coolness factor." lol

 

lmao!!

 

Or for 1/6 the price, you can just throw that same Holset turbo on the stock KA and make roughly the same horsepower. want more power? throw some forged pistons ($600) and bigger injectors ($100) into same KA and have 450hp for $2000 total.

Less coolness factor, but you can go just as fast for much cheaper.

 

But a KA is a truck motor....

 

I want my 240 to be capable of producing 700 whp. It's not like it will be driven very often with that much power, but it's just one of my goals. When it's all said and done I'll have spent less than $6000 (including the price of the car, not including suspension, brakes, wheels, and tires) for a 700 whp 2200lb rwd car. Although, I'm fabricating everything from scratch time=money...

 

other than the actual size and shape of the engine wat makes a vq so powerful and cant all the special additions just be mimiced on the ve and vg without goin through the whole swap

 

there are many more variables than displacement that go into making power.

 

I wouldnt consider the 240sx, stanza, or altima trucks...