ve vq swap out
06-24-2008, 05:25 PM
#121
if you're gonna swap the engine, anyway, your are better off swapping first, working out as many bugs as you can, and then, maybe, turboing. turboing the vg will be a waste as far as the ve is concerned, because you may have parts to reuse, but all the fabrication that went into the vg will have to be redone.
06-24-2008, 06:33 PM
#122
06-24-2008, 06:51 PM
#123
Look at some of the turbo systems that are coming out nowadays on street cars. the BMW 335i runs something like 10.2:1 compression on a factory turbocharged engine, and does it very well. Factory compression on a VG30E is 9.5:1. factory for a VE is 10:1. so the BMW runs higher compression than either of these factory engines AND is turbo'd. I have a few friends that own them and say they're an absolute blast to drive- turbo lag is all but invisible. It's a matter of doing the math right in the design phase, not just lowering the compression and adding a turbo.
06-24-2008, 08:07 PM
#124
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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
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.
06-24-2008, 09:43 PM
#125
Taking my Maxima to the Max!
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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.
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.
06-25-2008, 12:46 AM
#126
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Location: Redding, California
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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.
06-25-2008, 08:24 AM
#128
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
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.
06-25-2008, 08:24 AM
#129
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
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
06-25-2008, 09:21 AM
#130
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..
still impractical for most of us, and there's no need to drop compression in these cars to make decent power when turbo'd..
Last edited by Matt93SE; 06-25-2008 at 12:27 PM.
06-25-2008, 11:24 AM
#131
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Location: Redding, California
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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.
Last edited by Matt93SE; 06-25-2008 at 12:27 PM.
06-25-2008, 12:29 PM
#132
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.
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.
06-25-2008, 12:33 PM
#133
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.
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.
Last edited by CapedCadaver; 06-25-2008 at 12:37 PM.
06-25-2008, 02:29 PM
#134
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).
06-25-2008, 02:56 PM
#136
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).
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.
06-25-2008, 03:51 PM
#137
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Join Date: Dec 2007
Location: Redding, California
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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.
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.
Last edited by Mack531; 06-25-2008 at 03:54 PM.
06-25-2008, 05:41 PM
#138
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..
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..
06-26-2008, 03:37 PM
#139
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.
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.
06-26-2008, 03:56 PM
#140
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
06-26-2008, 06:29 PM
#141
Taking my Maxima to the Max!
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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.
06-26-2008, 07:12 PM
#142
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
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.
06-26-2008, 07:13 PM
#143
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.
06-26-2008, 07:39 PM
#144
Taking my Maxima to the Max!
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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.
06-28-2008, 05:34 PM
#145
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
06-30-2008, 08:28 AM
#148
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.
06-30-2008, 09:45 AM
#149
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.
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.
06-30-2008, 09:51 AM
#150
06-30-2008, 04:15 PM
#153
06-30-2008, 04:42 PM
#155
Less coolness factor, but you can go just as fast for much cheaper.
06-30-2008, 05:52 PM
#157
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.
Less coolness factor, but you can go just as fast for much cheaper.
06-30-2008, 07:14 PM
#159