Flow depends on the EXACT voltage applied including the drop across FPCU wiring gauge and the back pressure created by the fuel lines, fuel filter, fuel damper, rails, regukator return lines, and most of all the injector open time.
The Q45 system is designed to flow 3x demand so that the fuel pressure oscillions are < 2 psi at 7,000 rpm WOT.
Use an electronic pressure sensors and observe the PSI WAVEFORM at inlet to rail AND midpoint of rail to SEE what I mean.
what fuel pump to run and where to get it?
Re: (Q45tech)
Ok, that makes perfect sense to me, however, it completely avoided the question I asked and I think I understand why.
I believe if I hadn't thrown that whole engineering student sarcasm in there than you would've taken my question for a direct question which was what I was going for. A lot of the posts in this thread have gone as far as to point out the facts that the comparison of one pump to another has several variables and that the answer to the question of if one is better than the other is a question that forces you not only to consider what you mean by better but to also consider all the non constant dependent variables that have to be considered in the equation before one can begin to ask that question and be understood let alone to answer it.
But...... since I'm not asking anyone to break out their numerical analysis textbooks and/or software and solve the equation that appears to be at least a 2nd order Partial Differential Equation with what appears to be a minimum of 3 dependent variables and so on......(And if this isn't clear I hate differential equations)
All I was looking for was : "Yes that article is correct. The Walbro pump does appear to have a greater flowrate at the same pressure and voltage as the stock Q45 pump."
Because when I went to the parts store to grab a tank gasket and the guy at the counter pulled up the specs for the fuel pump first, his computer read that the stock S13 pump was good for 60gph or about 228lph, and I thought that to be way too high for a stock pump and so I asked about the Q45 pump and he brought back 80 gph or about 304lph and when I calculated the ratings for a 255lph pump I got about 67gph which I then thought to be way to low to feed the VH.
What it seems though is that if the article has any shred of credibility which I'd like to believe since it sites several sources that I would like to believe to be credible. Than the Walbro not only can support the VH it can feed it under some moderate fuel requiring mods. And this also would mean that Carl H is either wrong on his post of outflowing the Walbro with the stock pump or more information is needed for him to specify or clarify what he meant.
So the questions should've been can the Walbro flow enough to feed the VH? Followed by....How does the Walbro compare to the Stock S13 and VH pumps in terms of flow?
But to avoid any further confusion or lengthy typing I'll just go with what the article said
I'm not sure about the VH45DE and the VG30DETT having the same pump even with the added demands of a turbo the requirements aren't the same. The pump would need to flow about the same amount under boost but it would need to maintain the flow at high pressures than the VH would. Aside from that the part numbers don't match up The VG30DETT pump costs about $100 more in the places I've looked.
So that leaves me to further believe that the Z32 guys have a marginally better pump than us VH guys. And with that said and having read the test results of the article I would say that if you've got a real walbro GSS341 it should perform adequately if not a little higher flow and pressure at the same voltage than the stock one. And having read the testimonials of several walbro users I would say they (real walbro pumps) should last longer than the 6 months that others in several forums have warned.
So I'm throwing mine in the tank and we'll see how it goes. No more being spooked about things you read and hear. How does that saying go ....
"Only believe half of what you see and none of what you hear... "
Modified by EMK at 6:56 AM 8/24/2009
I believe if I hadn't thrown that whole engineering student sarcasm in there than you would've taken my question for a direct question which was what I was going for. A lot of the posts in this thread have gone as far as to point out the facts that the comparison of one pump to another has several variables and that the answer to the question of if one is better than the other is a question that forces you not only to consider what you mean by better but to also consider all the non constant dependent variables that have to be considered in the equation before one can begin to ask that question and be understood let alone to answer it.
But...... since I'm not asking anyone to break out their numerical analysis textbooks and/or software and solve the equation that appears to be at least a 2nd order Partial Differential Equation with what appears to be a minimum of 3 dependent variables and so on......(And if this isn't clear I hate differential equations)
All I was looking for was : "Yes that article is correct. The Walbro pump does appear to have a greater flowrate at the same pressure and voltage as the stock Q45 pump."
Because when I went to the parts store to grab a tank gasket and the guy at the counter pulled up the specs for the fuel pump first, his computer read that the stock S13 pump was good for 60gph or about 228lph, and I thought that to be way too high for a stock pump and so I asked about the Q45 pump and he brought back 80 gph or about 304lph and when I calculated the ratings for a 255lph pump I got about 67gph which I then thought to be way to low to feed the VH.
What it seems though is that if the article has any shred of credibility which I'd like to believe since it sites several sources that I would like to believe to be credible. Than the Walbro not only can support the VH it can feed it under some moderate fuel requiring mods. And this also would mean that Carl H is either wrong on his post of outflowing the Walbro with the stock pump or more information is needed for him to specify or clarify what he meant.
So the questions should've been can the Walbro flow enough to feed the VH? Followed by....How does the Walbro compare to the Stock S13 and VH pumps in terms of flow?
But to avoid any further confusion or lengthy typing I'll just go with what the article said
I'm not sure about the VH45DE and the VG30DETT having the same pump even with the added demands of a turbo the requirements aren't the same. The pump would need to flow about the same amount under boost but it would need to maintain the flow at high pressures than the VH would. Aside from that the part numbers don't match up The VG30DETT pump costs about $100 more in the places I've looked.
So that leaves me to further believe that the Z32 guys have a marginally better pump than us VH guys. And with that said and having read the test results of the article I would say that if you've got a real walbro GSS341 it should perform adequately if not a little higher flow and pressure at the same voltage than the stock one. And having read the testimonials of several walbro users I would say they (real walbro pumps) should last longer than the 6 months that others in several forums have warned.
So I'm throwing mine in the tank and we'll see how it goes. No more being spooked about things you read and hear. How does that saying go ....
"Only believe half of what you see and none of what you hear... "
Modified by EMK at 6:56 AM 8/24/2009
-
maxnix
- Posts: 22627
- Joined: Mon Jul 22, 2002 8:11 pm
- Car: 1995 Infiniti Q45
1995 Infiniti Q45t
2000 Infiniti Q45
Not Quite Kosher (EMK)
While you may be convinced, I am not. Going by Articles is just a rote way of doing things without understanding the underlying principles. You are at the mercy of the author's knowledge and his synopsis.EMK wrote:Ok, that makes perfect sense to me, however, it completely avoided the question I asked and I think I understand why.
Never go by part numbers between Nissan and Infiniti. They will always be different, even aftermarket. The Q and TT pump are known to be identical unless proven otherwise, it doesn't really matter, either one is more than enough for stock injectors.
Cool link I found...
http://www.stealth316.com/2-fuelpumpguide.htm
Oh, and Q45TECH always responds as above, technically. He doesn't know how to speak any other way. I think he wouldn't be able to sleep at night if he dumbed it down for us, I just try and understand it, then in my mind I convert it into usable redneck language.
Modified by T45 at 4:55 PM 8/24/2009
Cool link I found...
http://www.stealth316.com/2-fuelpumpguide.htm
Oh, and Q45TECH always responds as above, technically. He doesn't know how to speak any other way. I think he wouldn't be able to sleep at night if he dumbed it down for us, I just try and understand it, then in my mind I convert it into usable redneck language.
Modified by T45 at 4:55 PM 8/24/2009
Re: Not Quite Kosher (maxnix)
I was saying that I understood what Q45tech was saying.maxnix wrote:While you may be convinced, I am not. Going by Articles is just a rote way of doing things without understanding the underlying principles. You are at the mercy of the author's knowledge and his synopsis.
Not saying you are wrong as I have no real basis to say so. Just saying it would make sense either way but prices hurt.And that last comment made me laugh.T45 wrote:Never go by part numbers between Nissan and Infiniti. They will always be different, even aftermarket. The Q and TT pump are known to be identical unless proven otherwise, it doesn't really matter, either one is more than enough for stock injectors.
Oh, and Q45TECH always responds as above, technically. He doesn't know how to speak any other way. I think he wouldn't be able to sleep at night if he dumbed it down for us, I just try and understand it, then in my mind I convert it into usable redneck language.
Re: (Carl H)
This isn't really a reply to what Carl H said at all I just thought it would be helpful for some guys that may have had issues with the Walbros and most definitely for anyone who like me takes user reviews seriously and got kinda spooked by the stuff you've been reading.
The general opinion seems to be that for anyone who's looking for a fuel pump a Walbro can be a good cheap option that should be pretty reliable if a real one is purchased.
That made me dig around for a while to see if anyone actually knows how to tell the difference easily. That's when I came across this:
http://www.youtube.com/watch?v=7102yaOA2jk
Simple test just put 12v across the pump and let your ears tell you the difference first one is a real pump second one is the obvious fake. Then goes back to the real one again just in case you missed it.
There are also a few visual cues that should serve to set you on the correct path. If the pump is smooth and shiny and is coated in a thin film of oil in the packaging that's a good sign you have a real one.
If the pump is a rough surface and appears dull in finish like a casting thats a sign of the fakes. I know this is difficult to imagine so here's a forum where some guys have posted some great examples:
http://www.evocoupe.net/forum/viewtopic.php?t=2768
Top of page first pic is the real pump bottom pic is a fake. As far as the hoses and instructions and such I can't find consistent evidence to support that these characteristics can be used to distinguish real from fake.
And if it helps anyone out for ebay purposes I bought mine from Mk3tuner and it not only passes all these tests but it also was the best price for the complete kit shipped last I checked (about a week ago)
The general opinion seems to be that for anyone who's looking for a fuel pump a Walbro can be a good cheap option that should be pretty reliable if a real one is purchased.
That made me dig around for a while to see if anyone actually knows how to tell the difference easily. That's when I came across this:
http://www.youtube.com/watch?v=7102yaOA2jk
Simple test just put 12v across the pump and let your ears tell you the difference first one is a real pump second one is the obvious fake. Then goes back to the real one again just in case you missed it.
There are also a few visual cues that should serve to set you on the correct path. If the pump is smooth and shiny and is coated in a thin film of oil in the packaging that's a good sign you have a real one.
If the pump is a rough surface and appears dull in finish like a casting thats a sign of the fakes. I know this is difficult to imagine so here's a forum where some guys have posted some great examples:
http://www.evocoupe.net/forum/viewtopic.php?t=2768
Top of page first pic is the real pump bottom pic is a fake. As far as the hoses and instructions and such I can't find consistent evidence to support that these characteristics can be used to distinguish real from fake.
And if it helps anyone out for ebay purposes I bought mine from Mk3tuner and it not only passes all these tests but it also was the best price for the complete kit shipped last I checked (about a week ago)