vq35SMASH

so heres the deal, im on track for a decent power upgrade to my BONE STOCK BLACK TOP sr. so far ive got a s15 t28, dwerks 550's, Z32 MAF, HKS wastegate. on the way for the rest is a enthalpy tune, tomei procams, turbo SS lines, and a new exhaust manifold since im already there. and my question is this, my friends love the phrase "since your already there might as well...blah blah" and i have a old head off my old RED TOP sr thats been laying around for quite sometime. would it be benificial for me to p&p and do new springs seals and the whole laundry list of possibilities to the head and just put that on when i put the rest of the crap on? if so what would be the best course of action of stock stuff to leave and aftermarket stuff to upgrade too, and cane even a REDTOP head work on a BLACKTOP lower for a s13??

__________________
SLIDE SYNDICATE

LayNLow

I hate that phrase, I use it all the time when I end up having to replace something on my 240. Yeah the head will work, and yeah you might as well. It will help you get more power since you can flow more air through the head. Your call though.

__________________

vq35SMASH

I know right? But I'm pretty savi on most things but when it comes to internals that's where I get a little lost, would I just be better off getting OEM stuff or aftermarket? And what would be the things needed for a basic head rebuild?

__________________
SLIDE SYNDICATE

fliprayzin240sx

Fresh valveguides, seals and do a double rocker arm retainer guides. Fresh stock HG and ARP headstuds.

__________________

If you think Zilvia has too many assholes...
CLICK HERE!!!

4x4le

Since your already there is why my car has taken so long to get going.

Im not a fan of dwerks what so ever, and I dont like mail order tunes. Depending on the brand of the turbo manifold you are probably better off with the stocker. Im also not a fan of cams on these engines provided your not running a huge turbo that actually needs them. I have tuned cars for people that have later got cams and came back for a retune, and I am yet to think to myself "WOW, those cams did wonders", because as a matter of fact I always feel like they wasted money. Also I have tuned many similar setups with the main difference being one person had cams and the other didnt and I still feel like they are not necessary for anything t2 flanged and not necessary for most mild t3 flanged turbos. They sure sound nice but F that, who cares?

Just my $0.02, I think money could be saved on cams and turbo manifold and take that money to buy better injectors and a real tuning solution. That will yield you better results than any other part you could dream of throwing at your current setup.

inopsey

ive seen you post this about cams before, what size of turbo (gt series) would you consider them not a waste of money vs stock? been debating cams for a while now.....

4x4le

I held tq flat to 8k on my sr at 22-23psi on a 2871r .86 ar t2 flanged turbo. It was 376whp on a dyno dynamics. This was with rocker arm stoppers only and never threw any rocker arms.

I did change cams for my current setup that I have not got running yet but only because I lost oil pressure from the broken sump...... The cams may have been ok but I could see discoloring on the front lobes and a slight groove at the tip of the front lobes. The cams I went with were still stock nissan cams but the intake is from a usdm sentra se-r with the highport sr20de (fwd) and the exhaust cam is from a gti-r which yes the gtir was a solid lift cam but that same cam was sold by nismo as the "nismo" cam for hydro lift engines before jwt started making the nismo cams.

Both of my cams are now 248 duration but I would have been glad to re use the stock cams if I would have felt they were fine.


What it would take for me to want to use cams would be when I had a turbo that spooled so late that the only way for me to have a good power band was for me to increase how high the engine could rev and flow air effectively at that rpm. The issue with this for me and you is that with a stock ecu that is tuned there is no tuning that can be done past 8125rpm iirc. And Im yet to see an enthaply or jwt tune that scaled their tunable rpm range over 6800rpm!

So now say that you have a brand X ecu and you have stock cams and you dyno. Changing cams may very well increase your power but its not mostly because of the cams, its in spite of the tune.
If you had brand Y tunable ecu and tuned with stock cams and then changed cams to something aftermarket and then retuned you would be surprised to see how much you give up down low and how little if anything you gain up top.
Upgrading parts to make an inferior tune more useful is counter productive imo.

People add them by default on builds, so few people realize what they're not missing.

Im sure there are some people grumbling under their breath right now, if you want to prove me wrong post up some graphs, before cams and after cams, tuned for tuned. (no graphs will be posted)

steve shadows

I can tell you this about the motor and making power. Get a real ems that you can re-tune. Enthalpy will do for now but you'll want this later trust me. Love Enthalpy but he'd tell you he same thing, he told me that years ago and actually pushed me to be where I am today (I'm talking 2002).

5 angle valve job, deshroud the valves, gotta go to a guy who knows his shit seriously though to do that right, polishing and port matching is more importing than porting the shit out of an SR, the benefits are nil on just the porting end, slight porting and lots of polishing is what you want to do and it will help. We had an SR recently on the dyno we did, 12 psi of boost, 2871R .86 housing, stock intake manifold, 740cc injectors, AEM EMS - we pumped out 355 whp on a dyno dynamics....polished, very slight port and port match with BC 264 cams. Literally weren't even in the efficiency range at 12 psi on the turbo yet and we were already pumping out 355 on a Dyno Dynamics dyno (which if you don't know are the lowest reading in the industry) so we were very close to 400 whp on a dynojet basically. A lot of it was my tuning but the head work definitely helped a lot. So might be a good idea but make sure the guy knows what he's doing with the head that's critical.

If you don't have someone local you can ship it out to Cali and I can have it done by one of the best head guys in the world...he started portflow now he does his own stuff out of the south bay in a tiny little shop making Volvo motors pump out 1000 hp just for fun...don't ask lol

Might as well wait if you're going to do head work then throw the cams in then. But you're going to want an adjustable EMS because the head is going to throw stuff off, the cams will throw stuff off so just make sure Enthalpy can retweak it for you after the head work. You're AFRs are going to be off etc etc.

Hope this helps.

__________________
Like Me on FaceBook !

4x4le

I know we have duked it out before but that isnt what Im wanting to do here. I really would like to see the graph for this. I dont doubt for a minute that with a really good flowing head that a 2871r could make that much power on a sr at that low of a pressure but what I dont believe is that it had much more left in it after that. Otherwise why would anyone have stopped at 12psi after spending that much money on the head, the turbo setup, the ems, and then tuning to be like thats enough! stop there.

Im guessing there was 25-30whp more possible that that turbo could make and it would have been accomplished in just a couple more lbs of boost.

Flowing the heck out of the head just allows for less air to back up in the intake manifold and more to make it in the engine, so you flow the same amount of air at a lower pressure. The pressure its happening at is kinda irrelevant.

grab that graph up if you can.

steve shadows

We didn't stop after that we went up to 365 at 1 bar. We ran out of time on the dyno day, made sure it was safe for up to 18 psi and sent the guy on his way. I posted a huge thread about this dyno session and the car about 1.5 years ago or so but some newfag NEW mod who had only been with zilvia for like 2-3 years locked the thread saying it was advertising. I was literally just trying to show what or how much of an effect the head work had with those cams and some serious dyno dynamics time, but like you said the head work.

Trust me usually I am in the boat with everyone else where port/polish on high port heads doesn't really do crap and it's not worth the money but this and one other car I tuned a few years ago proved me wrong. may have the sheet still or if I can dig up that thread if it's not deleted, I know it's locked though on zilvia in the chat section somewhere.

__________________
Like Me on FaceBook !

4x4le

So, i know it was a while ago so its hard to remember but so at 1 bar, almost 3psi more it only made 10 more hp. How did you make sure it was safe at 18psi? Were any runs done there or was timing just pulled and fuel added? I have a feeling that turbo was out of breath, and was probably a high rpm engine.

Mikester

That statement is definitely one we always hear, but most people throw it out there with good intentions. For instance, I would say that since you have an S15 T28 and plan to tune for better power, you might as well get some rocker stoppers... I don't know nearly as much as 4x4le & co. but I know for FACT that they will agree.

As far as P & P goes, I didn't get one because my builder said that it's pretty easy to weaken the head if you're not careful- and there was no one they trust locally to do it. I am telling you this just to keep in the back of your mind; and I don't know enough to speak beyond that.

** If you are not planning to rebuild the bottom end while you have the head off, why spend money on anything more than you need to complement your mods? In otherwords, leave your current head on and build the spare over time so it will be ready for when you do a full rebuild.

Cams (Take what I say here with a grain of salt): Like 4x4le said above, upgraded cams may not always be the best choice. They may give you more power up top, but at the cost of losing low end... It's a balance. The S15 T28 is pretty small-output turbo by comparison; and when a lot of the Japanese companies tune with them, they either use 256/11.5 Poncams, or leave the cams stock. This is because you want to match where the turbo and the cams make effective power. If you look at a dyno graph, you will see that smaller turbines start to run out of breath in the upper mid - higher rpm... so when you add higher lift/duration cams; you run the risk killing the power band in an area where the turbine is designed to give good response.

Here is one of my old dyno graphs:

S13 SR20DET-

Turbine- APEXi AX-53B70R P20 (slightly bigger than S15 T28) @ 1.15bar (17psi) boost

Fuel- Sard 850cc injectors, 255lph pump & Sard adjustable FPR

Other- Z32 MAFS, FMIC, full exhaust, Rocker stoppers, Power FC

Cams- STOCK



Yes, it's a strange-looking graph; but it illustrates the point. Throw hp out, the focus is on the torque (light blue line). Notice where the good torque is... in the midrange (4500 - 6500rpm). Notice how smooth the curve is; and also that it drops off past about 6300-6400. An S15 T28's curve will look similar to this. If you add "too much cam," that curve will potentially narrow & shift to the right; so all that torque that you made before x-rpm will be gone at the expense of a narrower upper range due to the design characteristics of the turbo. Fuck max hp- a smooth, wide torque curve IMO is what matters. There is a whole bunch of other factors here that I am not even remotely smart enough to speak on... so I will stop here lol.

SOOO- for cams, I would recommend either 256 Poncams or leave them stock. The added bonus with Poncams vs. Procams (besides being better suited to a T28) is that they plug & play without need for upgraded springs, retainers etc.

Save all the bang & buck for when you are ready for a full rebuild~

__________________