GT2871R .86 Dyno @ 16psi

[DrifterProdigy85]

GT2871R .86 Turbo @ 16psiGreddy Intake ManifoldBC 264 CamsEnthalpy TuneApexi AVCR Boost Controller

I wanted to dyno 19psi but the boost controller wacked out and had it boosting 16psi on the dyno. Dissapointed at that but whatever, just something else to fix. Overall im surprised how flat the torque curve is. These BC cams are amazing.

[redtop91]

That's actually pretty good if those are the only mods you have.

[DrifterProdigy85]

Those are the only ones that make a big difference. Also have Megan Manifold, Greddy Elbow, 740 Injectors, Z32 MAF. Pretty much just the basics.

[redtop91]

I wouldn't be too concerned. Bigger cams and the extra 3 psi would put you close to 4 IMO. Have you ever used the .64?

[C - ROD]

some nice #'s, i cant wait till i get my motor back together to see waht kind of #'s i can lay dawn, im doing a full build of my bottom end, & i am going with the peakboost manifold & garrett turbo setup, i am going for 425++

[ILikeMy240sx]

That torque curve looks so nice.

Some solid lifters and reving past 8000 RPM will net you a bit more HP no doubt.

I cant wait till I dyno mine after seeing yours.

[DrifterProdigy85]

Im building the head next month but keeping the stock lifters and revving to 8krpm. Might of gained 5-10whp more by revving to 8krpm. Torque was already dropping at high rpm so the increase in HP starting to level off.

[codyace]

I wouldn't be too concerned. Bigger cams and the extra 3 psi would put you close to 4 IMO. Have you ever used the .64?

Bigger cams doesn't always = bigger numbers. Nothign personal against you, but thats one of the biggest problem with SR20 guys anymore...sticking some huge bumpsticks on t2 based or similar turbos. 260 to 266 duration cams are ALL you need to create the most potent street car you can. Why shoot for 400 hp when you can make v8 torque down low at the expense of some magazine hype peak number. Mean HP > Peak HP

With the turbo he has, the cams he chose are in the range of proper cams he should have had. I personally would love to see him throw a set of S3 or S4 JWT cams in there, but the BC units seem to be doing an adequet job as they are.

[redtop91]

I understand what you are saying but what is the practicality of low end torque on a dyno? He didn't say he was aiming for a particular street feel. Just numbers is what we are focusing on.

[codyace]

I understand what you are saying but what is the practicality of low end torque on a dyno? He didn't say he was aiming for a particular street feel. Just numbers is what we are focusing on.

So you're basically saying that you could give to hoots about how a car runs on the street, as long as you make big dyno HP??? Isn't that a bit to say the least?

Low ned torque is more important than anything....and where else than a dyno are you going to be able to see this. It's not going to change JUST because you're on the dyno....it's always there lol.

I'm fairly certain, that 95 percent of the guys on this forum would want a street car first, and a dyno queen second. I'm also fairly confident to believe that the car is VERY fun to drive as it is, and that the owner wasn't aiming for any partiuclar number or goal.

[redtop91]

I'm not trying to argue with you but you are being d!ck to say the least. I didn't say anything about what I want (which is also irrelevant). This thread is about a dyno sheet nothing further. Unless you are psychic you don't know what his plans are so your opinion on which horsepower is "better" is irrelevant. No point in continuing the discussion.

[karmakaze]

It should be pointed out that a dyno of a gt2871r .86 at 16psi won't do the turbo justice.

It does not enter its efficiency range until about 17.5 psi

[redtop91]

^ Have you used the .64 and .86 A/Rs? Is the .86 really as laggy as people would make it seem (compared to the 64 that is)?

[codyace]

I'm not trying to argue with you but you are being d!ck to say the least. I didn't say anything about what I want (which is also irrelevant). This thread is about a dyno sheet nothing further. Unless you are psychic you don't know what his plans are so your opinion on which horsepower is "better" is irrelevant. No point in continuing the discussion.

Now Im' really confused. You're calling my pyschic, yet you are the one that initially assumed as to what his goals were? Pot calling kettle black for sure. Not that I know the original poster personally, but from followinghis posts and threads, I feal as if I can relate to what his goals are, and what he wants to do with the car. Don't let my small post count fool you into thinking Im' some block headed newb.

You then claimed that low end torque on a dyno was irrelevant...which made me laugh. Torque is king on track. If you have some big laggy setup, that little 300/300 car is gonna eat you up, and make your big turbo car look silly....and thats why I brought up the torque point (and where you said it made no difference as he was looking at top end only.)

Not being a d!ck, just being realistic about the car. I prefer to not live out of the jegs catalog, and instead like to see stuff being done.

It should be pointed out that a dyno of a gt2871r .86 at 16psi won't do the turbo justice. It does not enter its efficiency range until about 17.5 psi

See that's where I don't agree either. It has the same compressor (accordingly the same map for it as well then too) as the .64 2871r. By doing that, assuming he can spool 16 psi at 4200/4500 rpm witht he larger turbine housing, it would put him i the 70/72 % effeciency range....which is DAMN good at that psi IMO.

The trick however between these to turbos is the turbine efficiency, which I have no clue how to read, and most manufactuers dont' even provide.

Again, 16 psi is just fine for this turbo.

^ Have you used the .64 and .86 A/Rs? Is the .86 really as laggy as people would make it seem (compared to the 64 that is)?

Looking over past setups, you would have seen that the .86 turbos generally spool 800-1000 rpms later than .64 housing setups, but typically gain 10-20 more peak hp. I'd rather take the 300+ ft lbs at 3600 than at 4400.

[redtop91]

LOL. You really don't know how to quit.

No point in continuing the discussion.

And the latter question was addressed to karmakaze.

[DrifterProdigy85]

Ive owned both and can say the the .64 is a hell of alot better on the street but the .86 will win in the 1/4 or Top End runs. The .86 has rediculously ****ty response/low end. Id honestly compare its drivability with a GT35R. Its all in what you want though. I heard great things from the .64 so i got that at first then after finding myself drag racing and highway racing alot the .86 became a better choice for the money. Since i already had the turbo, it only cost $250 for the Turbine housing and swap it on. Ill have to get my boost controller setup for 19-20psi and see what the car really has. Might put some 94 octane or higher in for 21psi. Anything higher becomes inneficient.

[DrifterProdigy85]

Also realize the dyno runs started after 3000rpm so the peak torque is a little later than other starting there runs at 2000-2500rpm. The car is real fun to drive as long as your above 4krpm and dont mind a second of lag. Hell, just Saturday i was running 19psi and beat a Kenny Belle Charged Mustang that was Dyno Tuned to 450whp. Wasnt even much of a contest. I had an extra 300lb guy in the car and pulled the Mustang by 4 cars from 45-130mph. I really need to get to the track.

[codyace]

Also realize the dyno runs started after 3000rpm so the peak torque is a little later than other starting there runs at 2000-2500rpm. The car is real fun to drive as long as your above 4krpm and dont mind a second of lag.

Well put. That's why I stress that mine is setup for HPDE abuse, and not drag racing or top end racing....there is nothing wrong with either way ya go though

Hell, just Saturday i was running 19psi and beat a Kenny Belle Charged Mustang that was Dyno Tuned to 450whp. Wasnt even much of a contest. I had an extra 300lb guy in the car and pulled the Mustang by 4 cars from 45-130mph. I really need to get to the track.

LOL I love hearing stuff like this. In my 'street racing' experience, it takes a 500 whp domestic to beat my .64 full weight s14.

DP85: I'm going to be playing around with my cam gears here soon to see what sort of spool/power I can find with them....I've heard nothing but good things about them (faster spool, more trq)...would like to see you run them to some day if mine project turns out well

LOL. You really don't know how to quit. And the latter question was addressed to karmakaze.

Use the quote feature so we all can know then. And I'll never quit when I know I'm right. You said somethign silly, admit it, move on.

[redtop91]

Ive owned both and can say the the .64 is a hell of alot better on the street but the .86 will win in the 1/4 or Top End runs. The .86 has rediculously ****ty response/low end. Id honestly compare its drivability with a GT35R.

Exactly what I was looking for. Thanks.

[Dugi]

sorry for the thread jack but I also had the GT2871R .86 A/R. but now i'm going GT3076R with .64 A/R. my question is how is the lag comparison?? more less or same lag??

[DrifterProdigy85]

I think youll have less lag than me.

Only reason i havnt really done Cam Gears is just not knowing enough about them and havnt seen anyone go indepth to explain how they effect the powerband.

[Deadrodent]

what did your guys 2871r cost you? did you buy it new or used and from where?

[karmakaze]

See that's where I don't agree either. It has the same compressor (accordingly the same map for it as well then too) as the .64 2871r. By doing that, assuming he can spool 16 psi at 4200/4500 rpm witht he larger turbine housing, it would put him i the 70/72 % effeciency range....which is DAMN good at that psi IMO.

The trick however between these to turbos is the turbine efficiency, which I have no clue how to read, and most manufactuers dont' even provide.

Again, 16 psi is just fine for this turbo.

nevermind that i used to use this turbo. when i hit 17.5psi till 21psi i new it. that was the sweet spot.

the .86 is a bit laggy.

i wanted more top end than the .64 could offer me though. so now i am building a bored sr22 with a gt2876r .86

i think that even on a sr20 the gt2876 will spool faster.

[DrifterProdigy85]

Yea. I think the .86 Turbine Housing is a little mismatched for the 2871R Compressor in terms of spool wise but it gets the job done as far as power goes untill i can afford Top Mount GT35R or GT40R.

[codyace]

nevermind that i used to use this turbo. when i hit 17.5psi till 21psi i new it. that was the sweet spot.

Trust me, I can feal it as well, but 16 psi is still in the sweet spot according to compressor maps. 20 psi is just 'more effecient' if that is such a term.

i wanted more top end than the .64 could offer me though. so now i am building a bored sr22 with a gt2876r .86

If you're building a 2.2 why not step up to a 3071 with a divorced housing (or even a normal 3071r.

Looking at compressor maps, the 2876 is going to requre some serious RPM to make power effeciently, but at the expensve of some boost pressure (probabyl due to it's lopsidedness). Ultimatly I think a 2.2 would realy work awesome with a divided 30r based turbo...

i think that even on a sr20 the gt2876 will spool faster.

Eyh, that would be a toss up. I would certainly love to see a dyno...again looking at maps it would be a close call to say the least...however there has got to be a reason the 2876r's are more popular...

[codyace]

what did your guys 2871r cost you? did you buy it new or used and from where?

Got mine 2 years ago from some random site that had them on sale..paid 1050 for it then..I know they're higher now.

I think youll have less lag than me.

Only reason i havnt really done Cam Gears is just not knowing enough about them and havnt seen anyone go indepth to explain how they effect the powerband.

Speaking with mike kojima and member Steve Shadows (on Z ilvia and FA), they both exclaimed that by advancing the exhaust cam gear 2 to 3 degrees(at a minmum) on the t2 based turbo setups is going to help with overlap issues, and make the engine just simple breath more effeciently. Both exclaimed newfound torque thoughout the rev range, as well as quicker spool up. Both said gains are sometimes also found by retarding the intake cam, but it's a hit or miss.

EDITED: Added what cams I was talking about
Modified by codyace at 10:29 PM 4/23/2007

[DrifterProdigy85]

Will advancing or retarding the Cam Timing mess anything up? Id hate to blow something from not knowing what im doing.

[codyace]

Will advancing or retarding the Cam Timing mess anything up? Id hate to blow something from not knowing what im doing.

I just edited my post to help out more, but as they said:

As far a cam timing, this is my personal opinion.

With a 2871 with a smallish .64 housing and a stock mainfold, you are porbably back pressure bound. In this case its better to spread the lobe centers, starting by advancing the exhaust cam 2 or 5 degrees, then trying to retard the intake 2.5 degrees at a time. Engine should run better.

Now if you were to run a bigger turbo and a longer runner equal length manifold with perhaps a divided housing and a pulse type design, I would try tigtening the lobe centers much like a nprmaly asperated engine to see what happens.

I am going to experiment with this on a 4G63 to see what happens (proper manifolds can just be bought for this motor) This did work really well on the XS GT-R.

(I can't find my PM from SteveShadows, but it's similar)

I'm sure you can go to far, butt only little adjustments are needed.

[karmakaze]

If you're building a 2.2 why not step up to a 3071 with a divorced housing (or even a normal 3071r.

all in time.

eventually i will go with a 3076.

[DrifterProdigy85]

Might just make cam gears an addition to my setup when i do the new head.