I have a fwd vq35 into my 03 se-r. Progress is going well. just have to do the lower crossmember. We are also boosting this engine, its out of an 03 maxima as is the harness and ecu.

I've been doing alot of research and why the low HP numbers on a boosted maxima vs a boosted Z or G. Now I realize there is a stock HP difference of about 27hp, but 8psi on the maxima is only doing about 300 whp, where a Z would be around 385. 85hp is a big difference.

I want the most out of my set-up and I dont want to have to run 15psi just to hit 420whp. What factors do you think contribute to this? manifolds,i/c, turbo???


Thanks guys

 

I believe the intake manifolds are different. Im almost positive that and the fact that the power peak is lower, prolly due to more aggressive cams in the Z also contribute to more power per/psi. And the exhaust manifolds are also prolly different seeing as how your VQ is for FWD and the Z's motor sits different in the engine bay. With a different intake manifold, and cams Id think you would be really close to Z's performance. BTW 8psi on a well tuned TT kit is easily over 400whp. 385 @ 8psi is more like a ST kit.

 

my set-up is a single turbo aswell, so i do expect slightly lower numbers. I'm almost positive that i'll install JWT cams once we are done with the swap.

thanks for the info so far

 

The intake mani is definitely the major part of it. The Z manifold is WAY better than the Maxima.

ECU is probably also not tuned as finely on the Max.

 

I would say the cams plays a huge part in it. if you look at peak hp on the z/g vs max youll see that it is a lot higher which normally means the cams are more aggresive and can produce more hp up top.. if you look at the tb kit z/g you'll see the power is all at the very top. it do'esnt peak early then die off like a muscle car.

 

Correct. The Maxima intake plenum is very restrictive when compared to the Z, and coupled with less aggresive camshafts is probably resulting in the vast majority of the power discrepancy.

Also, how are you running your exhuast system and downpipe setup?

 

we've yet to figure out a good way to run the manifolds, but I know no matter what way we do it , it will be somewhat restrictive. Under the hood space is a big issue.

But i'm running a 3" downpipe to a 3" exhaust. There is very little bend to the downpipe. I'd like to go bigger but its not physically possible.

i wonder how much higher the plenum is on the Z/G. I'm cutting it close to the hood now, but with about 3/4" to spare.

I'll also be switching the cams so hopefully I can improve the power curve

 

looks like its time to get a Z.

 

I would have loved one but I ended up with a sentra. I'm happy with my car though. And with a boosted VQ im almost wetting myself with happiness!!


What size turbo would you all recommend for this set-up? My goals (on a built motor) are in the area of 550-600whp. i dont intend on ever surpassing that. What turbo would be an ideal size. orginally we were looking at a gt35r but I dont want to go with a gt series anymore.

sugjestions................

 

For a single turbo? T66/ P trim...

 

+1

 

besides, 550-600 whp in that car and being fwd, TALK ABOUT PUSHING THE LIMITS! Also, I am not too smart about things like this, but wouldn't the VQ engine really throw the balance of a sentra way off? 70/30 weight distribution? Man, it will be a beast though.
Craig

 

It doesn't affect the weight distribution by more than a few lbs. The VQ is very light.


Anyhow to the original poster, where are you getting this info that 8psi on a maxima VQ35 is only resulting in 300whp? I've never seen a number so low as that, being a turbo maxima owner and a very active member on the maxima forum. Infact I only know of a single turbocharged stock vq35 maxima, goes by the name of pimpjuice on the maxima forum, don't think I've ever seen a dyno number from him however. 8psi on a wheezing old vq30 will put down 330+, that's a motor that only puts down 160whp stock, as opposed to the VQ35 which is around 200whp stock.

 

Im on maxima.org to. I just did a few google searches also, i saw one guy had dynoed 300whp on 8psi and just over on 10. I know more guys have put down more, but i was worried when I saw 300. I had over 300whp on my last 4cyl set-up and didnt want to go through the swap headache for the same power output. Its reassuring to hear that I saw low dyno numbers then! And to weight transfer question, the boosted Vq will weight about 120 lbs more, but i'm going to a c/f hood, dropped a/c and battery relocation. So maybe 75lb difference.

Ya, 550 is beyond pushing the limits. At 300+ I was peeling the tires until 50mph. I dont plan on running full boost for street use, and Ive gone to tein coilovers stiffened up. I'm using drag radials as my regular tires, so for the 1000km's they last, I should be alright.

Whats the spool up like on a t-66? And I was going with 550cc injectors, are they sufficient for this power level?

thanks for all the help and input guys, I just want to make sure I do everything right the first time, and get the most out of my set-up.

 

Mardigrasmax has a T-66 P trim on his built VQ35. I've got a T61 P trim on the VQ30 with a .83 A/R and I see boost onset around 2400 in 4th gear, 14psi by about 3800, I've got better piping than most though.

 

neoloc187- What do you think the GT37R would perform like? I was given an amazing price on one from PowertechPerformance. Im just worried It wont build boost soon enough. I much rather sacrifice over-all Hp for smoother drivability

 

I've never heard of a GT37R so I know nothing about it. I've heard of an old GT37 when Garret first came out with the GT series a few years ago but I didn't know they had an R version. There are many factors that affect when your turbo spools as you know, and without knowing the specifics (turbine wheel, A/R) I couldn't even begin to speculate. There's a couple guys with GT35Rs on 3.0L maximas, turbo97se and jcymax98se or something like that, and I believe jcy posted a datalog that included RPM and boost pressure so you can see his spool from that, and turbo97se has posted dynos so you can determine his spool from that.

 

I dont have specifics on the turbo either or else I'd provide them to you. The name was all that was given to me with out having to go back in my emails. But the GT37R does exist.

I am just skeptical of this turbo and whether it may be to big for this set-up. I'm almost positive that it will be the one I use regardless.

I'll search for those data logs and help to base my decision from that. Thanks for the info.