TurboB15sentra

The bottom line, is that Scott and Clark are both great tuners.

I've worked with Clark/Jim for almost 10 years, and have helped with testing of new/existing products. If you guys think for a second, that Clark doesn't know what he's doing.. then, you have no clue as to what you're talking about. The guy was building off-road racing engines for Nissan back in the 80's, when most of us were in elementary school. The guy worked with some of the earliest forms of fuel injection, and he/JIM have worked with Nissan, as well as several race teams, on designing engine components, camshafts, etc.. If it weren't for the years of hard work, put in by this company, I'd be willing to bet that the Nissan aftermarket scene wouldn't be half of what it has become. Other tuners that have worked hand in hand with Clark/Jim, are people like Mike Kojima (former Nissan engineer), Rob Cadle (former Garrett Engineer, who designed the GT series from the get-go), and Dave Coleman, to name a few.. These guys know what they are doing.

I have also worked with Scott and Martin.. Scott helped me to tune a prototype QR25DE engine back in 2003. We were running a old Electromotive TEC 2 standalone, and made 400+whp on pump gas. Scott was very efficient/quick in tuning with the TEC 2. I was surprised, honestly.. Very professional guy, and knows his stuff.

The bottom line, is that if you took the same car, on the same dyno, and gave each tuner a turn to try and tune for numbers/smoothness, etc.. you would get identical results. Both are great tuners.. but, Scott/Martin are nowhere near Clark, in terms of camshaft and engine design, as well as overall understanding of EFI, as it relates to factory ECU tuning. That's not an insult to either of those guys.. it's just a fact, and comes with years of hard work/experience.

Travis

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jspaeth

Your peak hp is really high, awesome.

Why is it so laggy? Okay, you have a .86 housing, but it shouldn't take you until 5,000 RPM to see 300 ft-lbs....

Cody's and similar setups make 300 ft-lbs as early as 4000 RPM or so. There has gotta be something you can do to make that torque come in earlier.

As of now, your "strong" usable powerband is only 5000-7500 RPM.


With that big of a turbo, you should be able to keep breathing well out to 8000 RPM....I mean at 7400 RPM, your torque is JUST starting to taper off.

I think if you slap on some slightly larger cams and build the head, you should be able to rev out to 8500 RPM and still make really good power.



Oh yeah, I just read....STOCK CAMS?????????? With stock cams, why is it so laggy?


Looks promising based upon peak torque and how much tq you are making even at 7500 RPM....

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SoSideways

Yeah most .86 housing 2871Rs I've seen usually hit full boost by 4500rpm or so.

Then again, he's running 24psi...

Maybe the timing isn't optimized where it would be spooling?

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jspaeth

yeah I would agree, especially with stock cams, he should still have better midrange than that.

And in THIS case (as compared to someone before who was talking about making tq at low rpms, like 2000-3000), the extra tq WILL make a difference.

Because in this case, there seems to be torque missing in the 4000-5000 RPM range, which IS important for racing, unlike the 2000-3000 RPM range

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codyace

Final drives would most certainly be more important to me, than worrying about VTC. Mechanical advantage will always win out for me. Sure we lost some total speed in 4th, but my car will do 128/130 topping 4th.


Yup! Scott/Martin/Chris are all top notch dudes!


The car has no muffler on it, and is very rich. It's sooting like crazy. Also, cheaper camera's will pick up on 'heat' and show it on screen. You see this alot at night too when the IR picks up the heat on brakes/exhaust. Looks like a cloud behind hehe.

And spray out the filter is the recirculation BOV at the end. He's got some sort of foam filter on it, which IMO doesn't filter for shit haha.

A custom tune is always best, that is assuming you/the tuner know how to maximize the setup. As before, if I was runnign a race car/race gas it would certainly have a custom tune on it to optimize where I will be. My 'goal' of this comparison was (as you and I agree) is to show how well they work out of the box.


Did this today with my sr20det.

9:1 cp pistons
gt2871r .86 @24psi
e85 only
and NISTUNE
Tuned by yours truly[/quote]

Damn you and your E85! haha I wish that was much more available around here...yeesh! Soon as I saw 24psi I knew there had to be some sort of octane in that puppy. Looks great, now put some cams in her I'm to afraid to crank mine much more, as I don't want her to get addicted to race gas hehe.

THat's crazy with the load. We haven't had much tire spin on the free weights until the 600whp mark on our dynojet...then we gotta use 4 straps or put some ballast in the trunk haha.



Yep!

Thank you for understanding this. All of the above mentioned guys are awesome dudes too. YOu summed it up best, these guys are on the forefront of Nissan tech.

PS: Is Cadle even around still? He's sort of vaniched recently hehe. My buddy actually had a custom turbo setup by him for his b14 back in 2001...we'll call it the 'potato with the ball bearings" man what a perfect little turbo. I would love to buy him dinner for helping make that real 28RS as well...that turbo really changed the scene undoubtedly.



Again, well said Travis. Thank you for posting here, good to have another person who has had experience working with both and also had nothign but good things to say about them too. Cheers!

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SoSideways

Travis is old school man.

I remember when he made that custom QR with the SR crank in it.

Hot stuffs.

Back in the day when FA was hardcore techie.

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4x4le

Sorry. Im not trying to fill this thread with my results, I just want to clarify a few things. I didnt go back and optomise my low end, I actually didnt touch it much. Most of the pulls were started at a much higher rpm but this was the final one just to have a fuller graph. I know there is more work to be done and I will be back for more. I doubt I will do cams to be honest but I may some day. I think hitting numbers like that on a Dyno Dynamics with stock cams is just too impressive to add cams.

When I go back we will play with the load on the dyno to make the turbo spool more like how it does in real life and I will start the pulls at about 1800 rpm and go to about 5500 rpms and optomise all of that part of the maps.

This is not a final tune for me. Just some of the work I did yesterday.


and here is the graph with the tq scale

jspaeth

That's just silly man. You already have a sick setup and a BUILT BOTTOM END!!!!!!!

Why would you not want to let the car rev out to 8500 RPM?

Cams and some upgrades prings/retainers and you are good to go?

I don't get it....it's literally like another 600-700 bucks for another 1000 RPM worth of revving and more power and stuff.

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4x4le

After I go tune the lower rpms I will have a much more usable power band. Then If I were to add cams I would just be shifting that power band in favor or a higher hp number (which I have enough of right now).

All in all, really what I need if anything is a stronger power band lower, not higher.
I agree I would love to see what kind of numbers I could get, but Im sure someone will come around with a similar setup for me to tune and Ill be able to see what it would do then.

If I were really into hp numbers, I would have done MANY things differently.... starting with the turbo.

jspaeth

I disagree with you.

It is always in your advantage to stay in as low of a gear as possible, due to gear ratios.

400 ft-lbs of torque in 2nd gear will pull MUCH harder than in 3rd gear....

That being said, your car is CLEARLY still making GOBS of torque at 7500 RPM.

You WANT to extend that powerband out as far as it can go, because all things being equal, you want to be in a lower gear whenever you can.

Cody....chime in?

I would add something like a 264/264 cam to help flow better and also an aftermarket valvetrain will let you rev to 8500 RPM or so.



Bigger cams will NOT hurt your spool up, because your spool up is ALREADY going to be 4500 RPM anyway since you are 0.86 A/R.


Ahhhhh you have to do it!

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jspaeth

Okay I jsut checked the numbers....

In a KA/SR tranny, the ratio of 2nd to 3rd gear is almost 1.45.


That LITERALLY means that if you are making the same torque in both gears, you will ACCELERATE 1.45 times as hard in 2nd gear!!!!

So, even if your torque drops off to say 250 ft-lbs in 2nd gear at high RPMS...you will be ACCELERATING equally as fast as when you are making 375 ft-lbs in 3rd gear.


I myself, did not grasp this until I sat down and tried to understand it......unless your torque is dropping of REALLY fast, you ALWAYS (in our cars) want to rev all the way out to redline (due to the way our trannys are geared).

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4x4le

Im buying a house right now. This month. Please let me make my excuses for now. I know the wifey wouldnt like me tearing into the engine right now.

TurboB15sentra

That last time I saw/spoke to Rob, was back in 2003, at one of the Mossy Nissan Oceanside car shows. I don't think he's working for Garrett any longer.

Yeah, the GT28RS was the turbo that really started the revollution for new/updated compressor/turbine technology. It showed that you could, in fact, have your cake, and eat it too. Quick spool up, and big power.. The "Disco Potato", known as the GT28RS, was originally designed by Rob and a few other guys, for a Miata engine. It was such a great turbo, that they turned prototypes over to people like JWT, Coleman, etc.. and those guys were the first to test with it on the SR. They also tested it on the QR25DE, which proved to be awesome. It started making boost at about 2K rpm, and made 325+whp on pump gas. I've personally taken one out to 350whp, on a low comp/built QR.

Anyways.. I'm rambling.. lol..

Travis

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TurboB15sentra

All this talk of revving out to crazy RPM, and making power?

Why not go with a VE head?



JWT is in the process of working up some hot VVL cams.

Travis

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TurboB15sentra

I feel old.. Big "3-0" coming up in a few months.

That car was a lot of fun!



Racing street bikes, from 60-160 (and winning), is always a kick in the pants.

Travis

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TurboB15sentra

This ^^^

It's tough to compare the transient response/spool up RPM, from dyno to dyno (even with the same car), as loading can vary wildly.

Travis

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jspaeth

THIS is what I am talking about!!!!

However, even though that head is good for a bizzillion RPMs.....

Someone on here (that knows their shit) showed me the calculation for Mean Pistion Speed.

And apparently, the SR with stock stroke is dangerously near the "factory standard maximum Mean Piston Speed" when it is at 8500 RPM....

I like all this tech talk :-)

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TurboB15sentra

Mean piston speed, with the stock stroke, @ 8500rpm, is 24.36 meters per second. Around 25 meters per second is considered the "safe" limit for a street engine. However, there are other factors to consider, such as piston acceleration (from BDC and TDC), rod angle, etc.. The SR doesn't have a large stroke, and the rod isn't super short, so, the angle isn't so severe, that it causes tons of sidewall loading. With a good set of rings, and some lateral gas porting, 8500rpm is safe for any SR bottom end, but, I would never spin one up that high unless I had a VE head to take advantage of it.

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jspaeth

Right....I met a guy last week though, who said that he was building a VE head SR that he was gonna rev to 10,000 RPM.

I was like "is that safe" and he is like that is fine.....

Ugh I never know what to think....

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TurboB15sentra

That would be around 28.6 meters per second.. I'm not saying that it's not possible, but, it'll be tough to keep ring flutter in check, as well as build a light, yet, strong enough piston to withstand that type of force. Why rev so high? Unless you have a powerglide, or something, you really don't need to rev the motor that high. lol..

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HemiCharger

Yeah but wasn't the GT28RS designed specifically for FWD sentra's? I have not seen any RWD SR guys running them. I like everyone else on here is running a GT2871R. I wish I would have gotten the GT3076 instead. You can always make more power with boost. I understand the desire for top end in our cars but why would you pick a .63 A/R over a .83 or whatever A/R? Is the peak really that BIG of a difference?

jspaeth

From the results I've seen/heard, 0.63 vs 0.86 is maybe 500 RPM difference in spool up time, but I think the 0.86 will keep breathing for at least another 500 RPM higher than the other one.

Again, high RPMs is good, because you always want to be in the lowest gear possible at a given speed (given that the torque is not dropping off super fast).

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codyace

It almost seems unreal on stock cams, considering everything I've ever seen with SR's (and that' nearly 8 years now myself, as I was KA before that). I can't think of a single other dyno near your 'power' (even with the big boost) on stock stuff hehe.

I do like the ability to load on the DD dyno...this is my single biggest complaint with the Dynojet we use.


See, to ap oint...with the SR you can run a smaller duration cam and probably gain some 'airflow' in the midrange...not needing to boost as much would provide much less stress on the engine for sure...but then again at 9:1 with E85, 24 psi is nothing.

While I can grasp your point, wouldn't we also need to figure in a 'time vs RPM' aspec to this? Having more power in a gear is nice, but lets just assume 3rd gear is a 2.5 ratio, and 4 is a 1.0. Even though you'd think the mechanic advantage in power production vs gear would be better in 3rd, could we also not argue that the time in gear in that 1.0 4th be better for total speed? (If this makes any sense)

Or is it just another factor in it all? Or am I just completly wrong hehe.

Ah, another issue with 'dyno fights'...the time aspect. I love comparing some cars over 'time' in WinPep but even that is hard due to different start RPM and the sort between different dyno's. A lot of people don't understand that the 'big hp' number may be impressive, but once you change that lower variable to time (instead of speed) all sorts of new things can appear.

The GT28RS was designed around the Miata, but adapted well to the Sentra. Remember that ugly brown 'disco brown' Sentra (hence disco potato) that was in every magazine ever 7ish years back?

Sure you can always make more power with boost...but you loose response. I'd take a faster spooling 400 hp anyday over a laggy 450. The numbrs may impress simple people, but it's all about performance in my spetrum.

A/R on the exhaust side is extremely important. If an engine doesn't breath alot, why run a big a/r and loose velocity? Run a smaller one, on a bigger compressor to make some good power. And is the peak difference that much? Not really...exhaust A/R in the 'generic sense' really doesn't in 'same family' turbos...not enough to make up for the lost spool up time. Now if you're throwing a turbo on a big cube car, then yes, you will then fight smaller A/R's choking motors.

Yep. 500 to 800 rpm woth of spool up, with a 10-15 hp gain sometimes. To me, that extra hp isn't worth the loss of response, especially with a smaller frame turbo.

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PoorMans180SX

Thanks for providing one of the most interesting SR discussions I've read in a long time.

Can't wait to tune with E85.

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HemiCharger

one thing you also have to consider is you are dyno tuning these cars for power. I did the same thing when I tuned mine but my tuner also hopped in the car and street tuned it with me making full 4th gear pulls to get the most out of it. It smoothed a lot of things out that could not be seen or done on the dyno. Additionally, why I like the Power FC is it will tell you when you go into dangerous knock and will pull timing a little so you do not go BOOM.

wannaB!

this thread is good stuff!!! i am sooooo happy to get all of this good background info! i will be going with Enthalpy in a few weeks!

TurboB15sentra

Nope.. The GT28RS, will easily run on a RWD SR motor. Dave Coleman has one in his S13. It was originally tested on a Miata, and had great results. Rob Cadle introduced the turbo to JWT/Kojima, etc.. (the FWD SR crowd) Nissan's Steve Mitchell actually gave JWT a proto (no VIN) 2000 Sentra SE, to build with a GT28RS. The car was nicknamed the "Disco Potato", because of it's chameleon paint job, and the fact that it looks bulky/shaped like a potato. So, the name "Disco Potato Turbo" stuck to the GT28RS, and has been that way ever since.



This car was well rounded, and was brutally quick in the twisties.

Travis

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codyace

I know you're trying to learn, but everyone on here knows this. Just read the thread my man, and save the general stuff for general Don't mean to be rude, but lets try to keep it in focus...

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4x4le

codayce:
Allot of the reason my power kept climbing is mostly due to the e85 and how I can safely keep throwing timing at it even at higher rpms. Im running 35* in the upper right of my timing map! Most gas sr's will not respond well to lots of timing up top and you are cut off on timing kinda early on gas sr's. I remember a dyno graph from australia (I may even be able to find it) where a fellow was running a stock t25 on a e85 sr and was making around 250 DD whp. The graph was SICK!

I also tend to think that there is an added theoretical compression. Im running an actual air fuel ratio of 8:1 under boost, so there is much less room for air in the cylinder than if I were running gas and at a 12:1 afr. Also, most of the fuel is now a high energy vapor that mixes well with the air. When it sprays into the IM and head it vaporizes allowing it to mix better.


What dyno were you tuning on? A DD will allow you to simulate any street condition. It also allows you go hold it at any rpm you want. DD is the best tool for tuning period.

And the knock sensor on a pfc is not a high quality listening device either. Stock ecu tuning allows for the same exact feature, Its just most of us turn it off.

HemiCharger

A Dyno Jet and yes e85 would be the way to go if you can get it in your area. I tuned my car on shell 93 v power and that is all I really can run with it. Differences in gas can make a big difference in the way our cars perform. E85 is for sure the way to go but I just can not get it here and that sucks maybe in a few years. Another thing too is you guys have built motors and I am running the stock bottom end. It has held together quite nicely but I would not really like to throw 400+whp at it and watch it die eventually.

I know to learn many of you guys have blow your motors up for fun but I do not want to watch a 3 grand sr motor grenade in front of me. They have come down a lot but that is what I paid 3 years ago.