Went to the dyno, this time I did it with an UNLOCKED torque converter (which is why numbers come out low, that is NOT what the car really puts out, but at least we know the curve).

1st of all, dynojet's suck! went with 16psi from the street and at dyno it was 14psi since no load. you can see it on the graph, afr was also in the mid 10s (11's on street). I did another two runs, the 3rd was at about 18psi, still rich in the 10s, same exact curve, however almost same power output!!! as if there is something holding the engine back after certain boost.

After 5600RPM all curves ended up the same (so weird). Looks like there is a big restriction at 5440 rpm where it suddenly drops. Can this be a manifold issue? I know my timing was low as well but damn. There was also no knock either.

Also, on the street while getting passed that 5500rpm, the engine was more prone to knock (the J&S told me). Discuss....

 

Dude I just recalled something from seeing your graph...


I too had that same drop off just before 5500. We noodled about this for a while, Fuel rail, MAF Voltage, piping, Manifold, turbine housing, etc... Many options were in the air at the time.

Def not an exhaust manifold issue, as I had the long-tube headers and you have the stockers. Def not MAF issue cus you dont even have a MAF and the same is going on. Not a fuel injector issue cus I had 440s and you have 555s. Surely not turbine housing, as yours is much bigger than the one on my old HX35.

Leaving us with only a few things in common as possible culprits; feed piping diameter, Intake Manifold, and fuel rail. (note that we only experience this after a certain level of WHP, so whatever it is... it's airflow-derived).

- Intake manifold can easily be tested by looking at the dynos from other boosted 3.5s with the FWD mani that are mid-300's whp+ range. Technically the same can be said about the fuel rail if they are using the same rail as us.

I think that after a certain level of airflow, the stock FWD IM just creates turbulence. Weather it's the plenum or the elbow. I would love to see what this looks like with the new custom IM that this guy made (forgot the name, this is recent tho). I would put my money on this as the factor... Also (sidenote) didnt Tilley's manage to mount the 00VI on a 3.5 LIM and proved that it made ubber power over the stock 3.5 IM? That's another thing you can look into to test out.

And so the hunt continues!

 

Damn eddy, thats an identical curve to mine, even the drop is EXACTLY the same. Hmmmm so its not stock headers.

This must be a FWD intake manifold issue, I have been trying to look for people with fwd and this kind of boost or HP but I dont think there are any lol. the few usually get custom manifolds. I have always been interested in the idea of the 00VI, but it will take a bit of work and still wont be perfect, I dont wanna go through all that. As for fuel rail, I think if it was a fuel rail issue it would show on the widebands as leaning out. (side note, they are 600cc sir lol).

For charge pipe diameter, that might be something else to consider, it is said that 500cfm is like the limit for 2", after that it just becomes a hot mess and inefficient, however what kind of HP would 500cfm be at? Edit: but wait, at only 9psi you still got that drop! its impossible for 2" piping to be a restriction on just 9psi, im ruling piping out.

Eddy, was this manifold on your dyno SSIM yet?

 

I think trying out a Z manifold would be easier than 00VI. Plus you know that FI Z's dont have that problem.

 

I think Tilley had a VQ30DET manifold at one point did he ever dyno it?

 

Yea agreed! Even at 337whp I had a drop off, and that's still below 500cfm IIRC from my compressor map math that I had done yrs ago. So the piping is def not an issue here.

Yes sir, I did have SSIM by the time I went turbo.

 

yo that's a good point!

 

00vi would be going backwards. Plenumn volume makes a big difference on bolt on 3.5's. (such as in sparks case with his custom IM) The 00vi has less overall plenumn volume than any stock 3.5 IM so you will do nothing but choke up the motor even more.

 

3.5 altima ser dyno'd 385@ 9 psi w meth and 2 extra injectors, stock timing, no drop off. also was auto. but it had a forward 2.5" feedpipe. ?????????? im sure if you go to twilight they can print the dyno for you if they or frank remember the name of the owner lol also was a dynojet. the guy used to work at wwr on an off the shelf gt35 .63 ar rear housing which is alot smaller than your hx40 ???


and isnt there a dyno of another turbo 3.5 tha put like 389 down??? did he also have this drop bc of the Intake Manifold? he had a forward feedpipe???

 

it does not have anything to do with the intake manifold, it's the cam timing

remember these other example's are of car's with varible cam or altered timing.

 

Agreed up to a point. It has already been proven that the 00VI holds power well passed the 3.5 FWD IM. Plenum volume isnt AS much of a factor with FI as it is with NA, since technically everything from the compressor to the intake valves is pressurized. The problem with the 3.5 FWD IM is turbulence, which the 00VI has considerably less, so I think it would hold power (even at that power level) much better than the 3.5 FWD IM.

HOWEVER, streetz makes a good point that to make it work would take time that he simply doesnt have, and it would still not be on point (given the mismatch of runners of UIM and LIM was the problem IIRC). So the Z33 IM option looks much more viable and beneficial than anything else ATM.

 

Oh yes! very good point to bring up. Overlap is another factor to look into here

 

Looks like we are getting somewhere here. I think the most economical solution would be the Z manifold with a spacer.

 

a bigger intake would be a temp fix and will alter the curve some but to really fix the problem well you'll need cams or different cam adapters

The cheapest, easiest and fastest thing would be a 350z intake, spacer and revup lim

 

Agreed. I think we found the problem.

 

Roger. So streetz' to-do list per us... 350z IM, and if that doesnt do it, time to mess with the cam adapters.

 

Yeah, the cam stuff is going to wait for a very long time till I have my place and another daily driver. For now, Z manifold would do.

 

This is meximax' dyno with Z manifold and cams: (not even a hicup at 5400)

 

oooh man, and with u shifting at 6k, this would be perfect (minus the cams, but that we will see once the Z33 IM is done).

Well done gentlemen, well done! Beers on me!

 

hey what you think about on below?:

http://forums.maxima.org/supercharge...5-4th-gen.html

this make over 420 whp?

 

Sorry for my segway post here, but I can't help but to wonder why turbo maxima's have such laggy power bands.

They look like 2L 4 cylinder dynos, but we are talking about 3.0L and 3.5L V6s here, so what gives? Are you guys using turbos that are way too big or what.

Dyno from my S4, which only has a tiny 2.7L V6.

FYI, the drop off after 6500 RPM is because of a issue I was having at the time of this dyno..(computer pulled out timing)

 

i think youre comparing apples to oranges, the above dyno is of a supercharged 3.5, and streetz has a large turbo. this car still had a bit too large turbo but powerband is much better on a 3.0 @ 10 psi..sorry cant find one w rpm vs speed but you see the difference

 

So Mexi is a blower setup huh, I guess that explains his power band.. I thought it was TCed.

 

Yes sir, SC VQ35 on a Maxima from about 5 years ago. The image linked by streetz is from my built engine. The lower compression and cams made for a not so strong low end torque, but beastly on top.

The image below is from my stock compression setup with the same boost setup. Notice the much beefier low end torque. The lower line in the chart is my NA pre-boost setup on a stock VQ35 with Z33 IM.

 

Yeah, that is a pretty big low end difference.

 

This caught my eye, cause the point where you're having your issues is the exact same point at which my car has some detonation/knocking issues:



My graph doesn't show as much of a drop as yours (due to a lack of a J&S to pull timing in my case), but it is definitely right in the same RPM ballpark.

 

So you too have that dip at around 5300! it HAS to be manifold or cams!

 

he says he sees knock at that rpm range and may cause that dip

 

Nah, it has to be a manifold/cam thing, mine wasnt knocking at that rpm. His knocking is probably unrelated to the dip.

 

the dip in his case can be related to the knock no? disturbing power? not sure i buy the IM theory.. maybe the cam timing, i still think you should slap a properly dont ssim on there and redyno , lock the tc this time. make sure the j&S isnt picking up false knock

 

ed's massive dip at that power level should have been caused by detonation, hed had a meth kit on there im sure hed hit over 390 witout that crazy dip IMO

 

The JS didnt retard a single bit, it lights up when ever it retards. I think these guys were knocking because of that restriction of the manifold/cams.

Ed's dip is identical almost a replica to mine, however mine was not caused by detonation, so I dont think his detonation was what caused that dip but were due to seperate issues (too much timing so it knocked, and cam/manifold choke). I have no doubt its an intake or cam issue.

 

That's the part that confuses me in bold. It's the exact point I notice my knock/detonation. I'm beginning to wonder whether or not it might be due to small air reversion inside the manifold due to the VIAS delete i'm running screwing up the lamellar flow of the air within the manifold. This is nerdy (and makes me appreciate the time I spent in Mechanical Engineering), but I'm thinking that the "hole" for the VIAS assembly is causing there to be a much larger pressure difference in a FI application and causing the speeds of the air in the different chambers to constantly speed up and slow down causing multiple boundary layers within the manifold.

Copy/paste from (good read btw): Fluid Dynamics: Real Fluids

Then it explains:
So this, to me, would explain why a SSIM or 350z IM (or even a completely bi-plane IM) would work/flow better due to there being far less possibility to cause these flow reversions. It's worth noting that it might actually keep the IAT's lower as well (due to less turbulence and friction in the air path).

TLDR: I think it's a manifold issue...

 

http://forums.maxima.org/forced-indu...ok-inside.html


thats w a maxima intake, give me time, and youll see my dyno w 6-8 psi and meth (: sure it will look like ed's without knock and will not have that drop off till pob 6k

 

Well, as i'm sure you're aware, that dyno was done on a full 3.5 (as in full timing with VTC's). I think it's a case of apples and oranges considering most 3.5 swapped 4th gens lack any dynamic control of timing or multiple plots of different timing scaling...

Also, if you'll notice there is an obvious drop in power just after 5300rpm (torque/hp x-over). While not hugely noticeable, it is there. I think it's less noticeable because of more dynamic timing control.

 

i was under the impression that vvtc didnt do anything past a certain rpm on the 5.5s

 

As far as i'm aware, it's continuously variable. i was trying to see if i could find any type of plotting for timing, but haven't been successful thus far.

 

Cvtc is active until 6200 rpm.


Streetz let me know if you need a 350z IM to mess with. I have both revup and standard lowers.

 

Thanx mike, i actually got mexima's mrevII manifold, just no time to put it on.

 

any update? if the manifold was the cause not sure the vvt would fix the "dip" any new track time? that new job got you busy huh..