Stock motor 2871 how much boost?

[Oneoverwrx]

Hey guys i have been searching around a little this morning for the limits onb a stock redtop. I have found people making 350-375 with no issues but I have yet to find someone who says i have made xxx at xx psi on a stock motor.

Reason for me asking is because i am tuning a buddies car with a 2871 with a .86 housing. Car has all the supporting mods/ bolt ons. Car has a little headwork but is still on stock cams. We are tuning with an safc. He is on sti injectors and a walbro pump. He has a nismo fpr but it is not on the car yet. The car is not a daily driver and we literally have race gas at the pump less than a mile from his house. My question is what is the safe boost limit for this car? Also can you max the stock motor out with pump gas boost(like 20psi) or would he benefit from 23-24psi and some 110oct. I am sure we would be at the limit of the efficiency of the turbo at that point but would the motor take it. Should i tune it on 93 to something like 15psi and then maybe tune a mix of pump and race to something like 20psi to be safe of what?? He is wanting 350+ and isnt wanting to build a motor until after this summer. Any help would be great.

Thanks
Phillip

[nevaland9]

GT2871Rs arnet that efficient above 20psi & if you love your turbo you wouldn't do above 20.

[punxva]

well it will last longer if you tune with something other than a bandaid, aka SAFC... it can be done, but the feeling is always in the back of your head is it going to blow when i get on it. do it right, be a good friend

[Monooxide]

There is a guy who made 395WHP @ 19PSI on a GT2871R and stock block with cams, the exhaust housing is around a .7* A/R(extrude honed).

http://forums.nicoclub.com/zerothread/213470

[jspaeth]

GT2871Rs arnet that efficient above 20psi & if you love your turbo you wouldn't do above 20.


People can safely make 400 hp with stock bottom end, and of course, cams, springs, retainers, RAS.....and usually the boost pressure is around 20 psi.


Take 1 psi drop through intake to compressor....so intake air is at 13.7 psi.

Take 1.5 psi drop between compressor outlet and IM, assuming you have a good quality FMIC.....

http://www.turbobygarrett.com/turbobygarrett/images/catalog/Turbochargers/gt28_images/GT2871R_472560-15_comp_e.gif


If you look at the compressor map versus airflow, you are best off near a pressure ratio of 2.5 psi, as the map extends farthest to the right there, and you spend a great deal of your time in the high efficiency part of the map

2.5*13.7=34.25.....34.25-13.7 = 20.55 psi.....

Now, that's at the compressor outlet.

Subtract off 1.5 psi across the IC and piping to the IM, and you get like 19 psi at the IM.


Again, if you lose 1 psi in intake, and 1.5 psi over intercooler, a 2.5 pressure ratio gives you 19 psi at the intake mani, or 20.5 psi at the hotpipe.


This seems to agree very well with the fact that most people don't run the 2871R a whole lot higher than 20 psi or so.

If you lose less pressure in your intake, then the corresponding "most efficient" manifold (or hotpipe) boost is higher, whereas the converse is true if you lose more pressure in the intake.

Also, if you are losing more pressure across the intake manifold, and measure boost at the intake mani/coldpipe, then the "most efficient" boost number also goes down......if you are measuring it at the hotpipe, the number doesn't change in terms of what you are reading on your gauge, and you then lose that many psi across the manifold.


I think it's best to measure boost at the manifold, but be conscious of the fact that the air coming out of the compressor is actually a psi or 2 or 3 higher than what you are reading.

I.E. on a T25, boost limit is like 14-15 psi. If you try to do this, but are measuring boost on the coldpipe, you are really running the turbo at 16 psi+ :nono:


Obviously a lot depends on how much boost you lose through your intercooler

[scooz14]

you should get something to monitor detonation, or pre ignition. as long as your are not getting any knock, keep pumping up the boost.

[jspaeth]

^ Wrong.

Just because you aren't getting knock doesn't mean it's not bad for the turbo or bad for your motor.

[GabeS14]

The stock motor will take 400 hp but I wouldnt be boosting 23-24 psi on stock motor, its like testing its limits.and the turbo's too.and for what?
keep it safe till you do some supporting internal mods, and decent tune.also you need a external waistgate to be able to boost that hi on the 2871
I would do 19-20 psi max on it even if done right...just because someone else made 400hp on stock motor doesnt mean your motor will hold up.

[Flybert]

Just get some cams and valvesprings or 330whp is going to be the limit.

[Oneoverwrx]

punxva- thanks for answering the question. I love safc haters. LOL

jspaeth- Thanks for the informative post. I am thinking going to about 17psi for right now and tuning to a 11.2-3 afr for now. I may have him mix a gallon of 110 in to a full tank of 93 just to be safe. It should raise the oct a point or two just for safety.

He does plan on doing cams soon i was just trying to get him something to work off of.

thanks everyone for you answers, i appreciate you all not telling me to search as i assure you i have done plenty of.

[jspaeth]

SAFC = :ghey: with big power setups, but I guess for now it will have to do.

With that much power, a standalone or at worst rom tune should be the way to go

[Oneoverwrx]

well i have had really good luck with an safc. I actually tuned an safc on a 50t srt4 last week and it made 416 on pump gas.

[slider2828]

It really depends I ran good 11.5 on 91 pump on my 2871r with stock bottom end. Ended cracking the edge on my stock piston... Maybe .5 inches at most. No Scoring no nothing on the side walls... It just all depends... I was running 16psi at the time. What can I say, you really push it... I ran a T25 at like 12 psi and the turbo blew.... BUt none the less... I run 17 on a built bottom end now.... and built head...

[Oneoverwrx]

ok guys.....some new news. He weighed the car the other day and with lightley stripped interior and 1/4 tank of gas the car weighed 2420lbs. Which got me thinking that his car was going to do well at the dragstrip. He has a welded diff and 26x8.5 MT slicks So it should hook up and last night i had my buddy with the 416whp srt4 race him and on a roll the were very evenly matched. The neon would start to pull away above 125 or so but up until then they were very close.

Question: What do 2871 guys run at the track? I am thinking he is going to be trapping 117-120 after last nights race. I am thinking he is going to be around 11.70 or so??AM I close at all?

[McRussellPants]

OMG.

what the fuck is this thread.

2871 will make power and be happy all the way to 24psi. particularly the .86.

SAFC omg SAFC omg.

Drag Racing 5 runs a month or something like that You Could probably run a Stock Internal Motor up past 450. I wouldn't dick with it, and wouldn't touch it with an SAFC.

stock cams and intake manifold your gonna be making around 350 no matter what you do. so you might as well just run 20psi though it for now and bump it up later.

[corriganjoshua]

Question: What do 2871 guys run at the track? I am thinking he is going to be trapping 117-120 after last nights race. I am thinking he is going to be around 11.70 or so??AM I close at all? There are so many factors that come into play once your actually at the track its hard to make a real accurate prediction.

[steve shadows]

OMG.

what the fuck is this thread.

2871 will make power and be happy all the way to 24psi. particularly the .86.

SAFC omg SAFC omg.

Drag Racing 5 runs a month or something like that You Could probably run a Stock Internal Motor up past 450. I wouldn't dick with it, and wouldn't touch it with an SAFC.

stock cams and intake manifold your gonna be making around 350 no matter what you do. so you might as well just run 20psi though it for now and bump it up later.

Wow McRussel you sound like me?

Haha / thread

[surge s14]

whats the stock spring for a 2871r set for? im in need of a new turbo... :) can i just bolt it on i need break in time

[jspaeth]

Depends on which wastegate you have.

[punxva]

punxva- thanks for answering the question. I love safc haters. LOL

jspaeth- Thanks for the informative post. I am thinking going to about 17psi for right now and tuning to a 11.2-3 afr for now. I may have him mix a gallon of 110 in to a full tank of 93 just to be safe. It should raise the oct a point or two just for safety.

He does plan on doing cams soon i was just trying to get him something to work off of.

thanks everyone for you answers, i appreciate you all not telling me to search as i assure you i have done plenty of.

i'm not really hating on it, ive been running one on my Ka-t setup and am just telling you from personal experience that with higher power levels you want to go ahead and just get a better form of tuning with my control other than hacking the signals aka safc and btm

[Z U L8R]

i wouldn't push it over 17-18 on 93 octane and wouldn't go passed 22psi on 110 octane, if all you got is an safc2....you're off to a bad start, with that said, if that's all you're gonna use to tune with, back the base timing down at least 2 degrees aka 13 degrees advanced instead of 15, and i recommend RAS.

my .02
Dave

[FusionR240sx]

i wouldn't go past 15psi with a stock paper thin headgasket

[bigOdom1]

this thread is full or fail with a spoonfull of useful information

[surge s14]

Depends on which wastegate you have.

what about the internal wastegate it comes with? (t25 inlet)

[steve shadows]

GT2871Rs arnet that efficient above 20psi & if you love your turbo you wouldn't do above 20.

Really? Show me the point on the surge island where it's totally tanked at 20psi?



I would feel comfortable pushing the 2871R out to about 22 psi max.

On a stock motor, on pump gas with a Front Mount Intercooler, 16 psi is safe.

I usually won't tune over this point, mostly because the gas we have here in cali is 91 octane and because the cams just won't let much more air in.

Camshafts are really the door keeper of cfm or airflow into the intake side of your engine.


A front mount intercooler is really mandatory over 250whp ranges. We have been doing heat soak tests with side mounts vs. cheapo ebay fmic on some of the car's lately using an IR gun. The Side mounts overheat completely after 1-2 passes. Just think about that when your trying to road race? all that hot air.

A good fmic mandatory (with decent placement and air flow) for saftey with your tune with regards to setups like the OP is talking about.

[makdaddynuge]

not meaning to thread jack, but STEVE SHADOWS, how were your ebay intercoolers doing?

[Oneoverwrx]

We now have an apexi hg on the car and are going to go to the track this friday. We are going to try to run about 18psi on a mix of 93 and 110. This should definately eliminate any knock and keep the afrs a little on the richer side. After this we are going to do cams and possibly an intake manifold. Might send a stocker to get extrude honed. Has anyone had experience with that or is it better to just buy one like the greddy?

[Blown240sx]

Oneoverwrx where in KY are you located?

Also richer isnt always better. Too much fuel can cause issues also.

[Oneoverwrx]

I am in richmond. I know richer isnt always better. But if it is in the mid 11s on race gas with absolutely no knock i doubt we will have a problem. I was just saying i wasnt going to tune it on the edge even though we would have the cushion of the 110 octane. I had it at 11.0:1 all the way acroos the board on 93 at 14psi and it was really strong so at 18psi with some 110 and some minor adjustments it will be very safe.


Where are you at? in ky i assume.?

[Blown240sx]

Bowling Green

[steve shadows]

not meaning to thread jack, but STEVE SHADOWS, how were your ebay intercoolers doing?

What are you talking about?

I use PWR or GREDDY IC, only.

[garbury]

ive been running 18 psi on a 2871 .86 since August. I drive my car daily, about 150 miles a week and get on it very frequently. I run 91 octane and have all supporting mods including a wideband, stock cams and I just put in RAS. I've got a ROM tune from CG tuning, and he left the timing map pretty safe and I've got 11.6 afrs once its wot.

BTW arent sti injectors kind of small? I'm running 850cc sards, but wouldnt mess with anything lower than the nismo 740s if you want to push the turbo.

Also,

[Oneoverwrx]

We are on an safc so we cant really play with timing.One change is brian crower 264s were installed. Car was tuned on 17psi and went [email protected] on saturday. It had been some 11.90s but we were running 1.88-1.89 60' times. Finally got a decent launch went a 1.69 and dropped that much off his e.t. Car still has a lot of room for improvement as we plan on turning the boost up and still have to work on the launch. With a 1.5x 60 and some extra boost the car should dip into the 10s.

I do agree that the sti injectors are a little small for what we are doing but we are running 110 oct all the time. The car might get 20 miles a week on it so it isnt a big deal. We will probably go to a bigger injector later.

With the 110 at 17 psi we were safely tuned at about 10.90-11.20 throughout the entire band. SO there is a lot of improvement there as well

[usdm180sx]

We are tuning with an safc.

Stop right there. If you are tuning a 2871r for 350+whp with an safc you shouldn't be tuning motors. Get a stand alone, get a tuner who will do it right or don't do it at all and do your friend a BIG favor by saving him the cost of rebuilding a blown motor.

[Oneoverwrx]

lol run some similar times and come talk to me.

He has been talking about buying a power fc so we can put a good tune in the car but we are working with what we have and doing really well. The car is on 110 octane and 17-18 psi. Stock timing and 11.0:1 afrs. This motor wont blow up for a long long time at this rate. LOL There is no way it is knocking and it is completely safe.

[dynamicck]

High boost and drag racing never equal long motor life.

[Oneoverwrx]

17-18 is high? LOL

I would say a drag car of this caliber and with low timing, low boost, safe afr, high octane would generate a long life of the motor. Now i would say that the driveline might not last long.

I believe he is going to build the motor over the winter and i doubt it will do me any good to ask here since you guys think 18 psi is high boost but....How much boost will a stock block with cp pistons and maybe pauter rods take.VS a sleeved block with same rod and piston setup?

I talked to ron(RAW Performance) formerly axis about an sr20. He told me that the stock block unsleeved was very strong. I would say that the most this car will ever see would be 25psi on something like a 30r. Probably make in the 550-600 range if we decide to push it a little or go with a 35r.

Are there people on stock sleeves making 500+ or do they need to have sleeves to make good power?

[dynamicck]

Sorry I thought you meant 17-18 on pump and 23-24 on 110. I got your previous post and original post mixed up.

You dont need to sleeve it to make 500hp. It's been done w/o resleeving.

[golfer17]

I've ran anywhere from 12-20psi (I change the boost often so I don't get tired of it) on a stock longblock sr20 now for almost two years, and consistent 17psi for the last month with my 2871r, self-tuned with only an safc (with 480 injectors though I don't have to correct as much), and the car still runs as strong as it did whenever i first put the engine in. However, I check my wideband every day, the first time i get on it to make sure my afr's are good, and I rarely run more than 15psi on pump gas (I run an e85 mix now). so yeah, I think 350-400whp should be safe on stock internals as long as you have a good tune, check the afr's often, and always add a good safety factor with race gas when running more boost.

[Oneoverwrx]

car is on race gas only for the rest of its life as i have said. The car is only driven about 15-20 miles per week and we have 110 on pump about 1 mile from the house. Also as i have said the afrs are very safe in the low 11s on 110 oct and the boost at a low 17 psi for 110 oct gas.

Last weekend we took the car to a midnight mayhem event at a local track and the weather was great for a turbo car it was getting in the low 60s and the car was loving it. This track however doesnt hook nearly as well as the track the car was previously at but the weather was better and here are the results. Car went an 11.39 at 125 mph on a 1.83 60ft. Assuming we can get the car hooking better with a little suspension tuning the car will go in the 10s. With the little that is dont to this car it makes me wish i had one. If the car had 60d like it had the previous week you would be looking at an 11.10-20 car and i am almost positive we can make it go in the low 1.6s and maybe high 1.5s. This in itself would probably result in a 10sec pass and if not we still have plenty of room to make more power. Probably could lean it out a full point or turn the boost up to about 20-21 and go from there.


How fast has anyone ever been on a stock sr20 with cams only?

[golfer17]

car is on race gas only for the rest of its life as i have said. The car is only driven about 15-20 miles per week and we have 110 on pump about 1 mile from the house. Also as i have said the afrs are very safe in the low 11s on 110 oct and the boost at a low 17 psi for 110 oct gas.

Last weekend we took the car to a midnight mayhem event at a local track and the weather was great for a turbo car it was getting in the low 60s and the car was loving it. This track however doesnt hook nearly as well as the track the car was previously at but the weather was better and here are the results. Car went an 11.39 at 125 mph on a 1.83 60ft. Assuming we can get the car hooking better with a little suspension tuning the car will go in the 10s. With the little that is dont to this car it makes me wish i had one. If the car had 60d like it had the previous week you would be looking at an 11.10-20 car and i am almost positive we can make it go in the low 1.6s and maybe high 1.5s. This in itself would probably result in a 10sec pass and if not we still have plenty of room to make more power. Probably could lean it out a full point or turn the boost up to about 20-21 and go from there.


How fast has anyone ever been on a stock sr20 with cams only?

wow, awesome time! 125mph on 17psi sounds really fast (i'm only hoping for mid-teens from mine). what's the setup like to get it that fast? (weight, other power mods, suspension setup, etc)

[Oneoverwrx]

Car weight is about 2400 without driver and with 1/2 tank of gas. It is a s13 hatch car.S13 black top, BC 264 cams, 2871 with .86 ar, apex i intake, megan racing tubular manifold, Circuit sports downpipe, buddy club exhaust, Hybrid FMIC with hks ssqv. Car is of course tuned with an safc2. Car is on sti injectors and walbro 255 fuel pump. He has a nismo fpr but havent installed it yet. Car was on M/T et drag slicks 26x8.5x15 tires. Has JIC coilovers but need rebuilt. Car has a welded rear diff and stock axels.

that is about it i think.

The key with doing well at the track is traction. If you can make a car hook it will do better than if you just make gobs of power. I definately think a car with a t25 and cams could run some low low 12s maybe get into the 11s with a tire and some driving.

[steve shadows]

lol run some similar times and come talk to me.

He has been talking about buying a power fc so we can put a good tune in the car but we are working with what we have and doing really well. The car is on 110 octane and 17-18 psi. Stock timing and 11.0:1 afrs. This motor wont blow up for a long long time at this rate. LOL There is no way it is knocking and it is completely safe.


if you want to run 10s just get a standlone re-tune and you will find another 30 whp or more lurking and the car will run better in every part of the map and also cooler

it's like beating off with jam instead of baby oil, why?


How fast has anyone ever been on a stock sr20 with cams only?

I did 11.8 @ 121 mph with stock sr with stock cams (100% stock long block and stock im with afc and tuned rom)

But I hated the way it drove, Since using haltech the car makes more power at 12.5 psi with a gt30 r than it did with the other setup at 26 psi with a 62-1/t3 turbo, it's cooler, more efficient and has lasted at over 400-450 whp levels as a weekend and track car for more than 2 years now.

Still using stock bottom end. When I was using the afcs I would fry pistons every 4 drag comps.
Only thing diff is IM and Cams + Haltech

[Oneoverwrx]

well an ecu is definately in the cards but just not in the budget right now. Would like to get a intake mani on the car as well.

[Oneoverwrx]

well guys we went back to the track on friday night. The air was a little cooler but we left the exhaust on the car(not thinking about it). We added a little weight to the trunk(50-75lbs) car went a 1.59 60' went 7.11 in the 1/8th and a 11.15 in the 1/4. It went 97 in the 1/8th but only went 123 in the 1/4. I think the exhaust made a little difference and i think the shift to 4th was a little slow. But this was still on 17psi and mid-low 11 afrs. We need a camber kit and a little more time to test so we can get the car to leave straight and we will dip into the 10s. I have a video of the 11.15 that i will post later.

[steve shadows]

congrats on the time. I think I'm going to head back to strip in August looking for a sure 11 too

[Oneoverwrx]

here is the video. We added a little weight as i said and the car left fairly good, we just need that camber kit and im sure it will go in the low 1.5s. Next time to the track will be 10s or bust!!!

http://www.youtube.com/watch?v=FweEsmx9uXw

[golfer17]

if you want to run 10s just get a standlone re-tune and you will find another 30 whp or more lurking and the car will run better in every part of the map and also cooler

it's like beating off with jam instead of baby oil, why?

I did 11.8 @ 121 mph with stock sr with stock cams (100% stock long block and stock im with afc and tuned rom)

But I hated the way it drove, Since using haltech the car makes more power at 12.5 psi with a gt30 r than it did with the other setup at 26 psi with a 62-1/t3 turbo, it's cooler, more efficient and has lasted at over 400-450 whp levels as a weekend and track car for more than 2 years now.

Still using stock bottom end. When I was using the afcs I would fry pistons every 4 drag comps.
Only thing diff is IM and Cams + Haltech

When I first saw this post, I was about to try and argue in favor of a tuned rom with safc, however now that I have a mail order tune loaded onto my computer and have compared it with the stock map, I understand why a standalone can be so much better than a mail order tune/safc (though I think I would still prefer tuning the stock ecu in real-time with something like nistune for my purposes).

You have me a little worried though now about frying pistons with the safc. How much fuel were you having to take out/add in at the top end? I’ve ran my car over a year with just the safc pulling out a max of about 20% fuel and boost levels from 12-20psi, and now that I have a mail order tune on it that I was hoping would get things a little more accurate and to where I don’t have to take out fuel, I’m actually adding in 20% fuel and it’s worrying me a little bit. Even though I’ve checked the timing map and the values seem to be decreased slightly from stock, it’s just really been worrying me that now that I’m adding in fuel instead of taking it out, I’m now in a completely different place in my timing map than I was before.

Car weight is about 2400 without driver and with 1/2 tank of gas. It is a s13 hatch car.S13 black top, BC 264 cams, 2871 with .86 ar, apex i intake, megan racing tubular manifold, Circuit sports downpipe, buddy club exhaust, Hybrid FMIC with hks ssqv. Car is of course tuned with an safc2. Car is on sti injectors and walbro 255 fuel pump. He has a nismo fpr but havent installed it yet. Car was on M/T et drag slicks 26x8.5x15 tires. Has JIC coilovers but need rebuilt. Car has a welded rear diff and stock axels.

that is about it i think.

The key with doing well at the track is traction. If you can make a car hook it will do better than if you just make gobs of power. I definately think a car with a t25 and cams could run some low low 12s maybe get into the 11s with a tire and some driving.

very impressive. I'm still too afraid of breaking my axles or tranny output shaft or clutch or something to bolt on my buddy's slicks and see if I can't hit 11's.

[idahotuner]

oneoverwrx did you check out my thread i posted today? here is a linkhttp://zilvia.net/f/showthread.php?t=202951

[Z U L8R]

11.0's are safe air fuels but i'd still back the base timing down 2 degrees and keep it right under 12's with a little extra fuel up top if it were my/customer's car. congrats on the good times tho and i hope to see the 10 sec pass on vid. good stuff, keep it comin brotha

Dave @ Lethal Injection Motorsports =]

[Oneoverwrx]

i just checked your thread idaho...nice numbers. I would love to dyno tune this car. We were thinking about doing a tuned ecu and then tuning on it more with the safc.

Im sure there is more left in our car as it is safe everywhere it can be. As i said it will hit 10s next time at the track and i will have video for you guys. Thanks for the support.

[Oneoverwrx]

ok guys....we tried tuning for 20psi but ran out of injector. The 110 helped us stretch the 550s pretty far but about 17-18 psi is all on 110 octane fuel. We may try some c16 but i dont know. We did get the car aligned so it should leave straight.

[Erjay1]

Any updates? Did you hit 10's? Did the motor hold up?