We get a lot of people asking what RPM the S252 turbo in our LNF upgrade kit spools at. Since we usually start our dyno pulls around 3500 RPM, it doesn't show what the turbo could be capable of at 3K and below. While there are a lot of variables, we have found that this turbo can spool at 2500 RPM if the engine is loaded hard enough. This can be done by starting out in a higher gear or by brake-boosting. Here is a pic showing 21psi at 2750 RPM.

This was done by starting out at 40mph in 3rd gear with the brakes partially applied. It is important to note that this car has tall tires and tops out 3rd gear at 125mph. If I were roll racing, I would start in 2nd, even at 60mph. Basically, there is no reason to ever be WOT in 3rd gear at 40mph. This was simply done to show how the turbo responds and/or entertainment purposes.

 

Yeah most don't realize that spool point can change depending on load, and gearing.

I can get my 2871r to spool at like 2500 at 40mph in 4th gear... LOL


Good info.... I just need a clutch so I can finally turn the boost up some!

 

^^ what is your A/R size? that plays a role in it too.

Well this question goes for both ZZP and blueberry/

 

.55 on our turbo

 

.64 on my PTE 2871r

so all in all mine is just a TAD larger but not by much

 

Kind of an irrelevant test. I think it's more interesting if you just go out in 3rd gear, at 2k rpm, and floor it.

You can make any turbo spool faster by artificially loading it. It's also a pain to tune for if you don't have the ability to control boost/wg by gear.

 

The point is that if the car is accellerating quickly, then it may appear that the turbo is spooling slowly on a dyno graph, when in reality, the car is just getting to higher RPMs quickly. Yes, I could start at 2000 RPM, but then it will be just like last time when someone asked what our twincharge setup does if you floor it at 1000 RPM. The point of this was to show that this turbo will spool at much lower RPM than you should ever need to have your turbo spooled at...and it makes power to 8000rpm, making it a perfect match to this motor.

 

nice! i love my BW!!!

but i need a bigger unit for my twincharge goal, to bad you guys dont do exchange program lol

 

*Drools*

 

So this was on the dyno?

Given enough time (within reason), any turbo can be spooled up early as hell by holding the rpms at one point and applying full throttle. As boost starts to enter the picture (even a little bit), exhaust volume will increase, and boost will climb. If it took 10 seconds of steady state, 100% throttle to get the turbo to that level though, I wouldn't say you can spool the turbo at that rpm, because it's not repeatable on the street (or good for the car).

Although, as you mention, people think a late spool is always the turbo. There are many ways to improve spool on a turbo/engine combination, it's all about airflow and exhaust volume.

 

It took about 3-4 seconds, and I disagree. A big turbo will not make 20psi at 2700 RPM regardless of how you do it(excluding nitrous). I've dyno'd at least a dozen different turbos on Ecotecs, so I'm not basing this on speculation or guesswork.

 

I understand where everyone else is coming from. The question i have is say your in second gear off the throttle at about 3000rpms on the street then floor it, how long does it take for it to react then? i know our factory turbo takes about 2 seconds to build full boost "depending on your cam settings" but if the timing there is about the same i may look into this kit eventually. Do yall have any plans on selling any of the individual parts? for example that nicely designed manifold and down pipe set up? or the turbo alone?

 

Was this test done on a car with your ported head?

I don't understand what some people are expecting from any particular turbo - you are always going to have compromises. You cant have tire shredding torque at the bottom of 2nd gear and also have steady power up to 8k rpm. If that's what you think you need, you'd better consider a bigger engine .

I'll admit I'm spoiled by the stock turbo's extremely low rpm response, and would have to get used to the lack thereof with a big turbo swap, but it seems like people are caught off guard by that trade-off and need to be educated a little before upgrading.

 

Well said. If there was no trade-off, then the stock turbo wouldn't be so tiny.

No ported head, the motor is stock aside from ZZP valvesprings.

 

I bet if someone builds a 2.4L stroker Ecotec LNF you could get a big turbo to spool up full boost 500-1k rpms quicker (depending on the size), just from the added displacement. Its a relatively common swap in the DSM world to go from 2.0L-2.4L for more torque (not that we really need this) and faster spool up on bigger turbo's.

 

I never said that there wasn't a trade off. Bigger turbo = more lag, assuming they use the same sorts of technologies like twin scroll, bearing types, etc. My beef is that the test was irrelevant because it's an unrealistic situation. Brake boosting to get these results is lame, and unnecessary. Just give us a log of boost and RPM from 3rd gear, starting around 2100 or so, which is a realistic RPM that you'll wind up with when you shift into 3rd.

What you should also point out is that 10 psi on the stock turbo does NOT equal 10 psi on a bigger turbo. The bigger turbo is moving more air, and at higher pressure, it will be moving more air at the same pressure, but cooler too. If you do the math, you can find out where you're out flowing the stocker. That's great info. Also why start the dynos at 3.5k?

 

I've done over 200 dyno pulls on this car, and posted dozens of them. It hit 525ft lbs at 3600rpm without brake boosting. People still asked what this turbo is capable of and I posted these test results. Then you call it lame and irrellevant. lol.

I think it's pretty obvious that the same amout of boost on this turbo is nothing like the stock turbo. The S252 makes 450whp at 26psi while many setups struggle to hit 300whp at 26psi on the stock turbo.

 

Regarding the previous dyno posts, honestly, I never really looked because I got the car in December. You started that big thread before I started reading much here. I got this car to track, and as far as I can tell, the turbo is way too big for road course use. Fun for drag and highway I'm sure, but not really for me, so I never really looked at your thread.

Anyhow, I called shenanigans on this thread because I don't like to see unrealistic claims. So there it is. Make 20 psi in 3rd gear by that same rpm in a real world situation. If you can't, then I stand by my previous statements. I don't think I said anything inappropriate.

 

I'm just not following you. How is it unrealistic? People brake boost all the time on roll races. People with autos brake boost every time they get ready to launch. Why would you only call it "realistic" if I start at 2000 RPMs and just go WOT from there. To me, that is completely unrealistic because I would never need to do that in any situation other than simply seeing what happens.

 

Just above 2k is where most drivers will wind up after a shift. I like to land around 2100 to 2200. What's wrong with wanting to floor it after shifting?

Roll races? Seriously? If that's what this is about, I'll apologize and just stay out of this thread.

 

I assume you mean you land at 2100 to 2200 after a shift when you are casually accellerating away from a stop sign. If that's the case, I don't understand why you would want to grab a gear and then decide to floor it. That seems like a strange thing to do. I only floor it when I want to go fast, in which case, I would stay in the lower gear rather than short-shifting and then flooring it.

The thread isn't about roll racing. It's about demonstrating what the s252 turbo is capale of. Coming up with different scenarios doesn't change the data already proven.

 

You need to read the previous threads to see why Matt did this test. That's why you have such a problem with it. He ALREADY did extensive "relevant" "real-world" testing, and it looks like in an effort to satisfy those who still wanted more (ie data under 3500rpm) he did this test.

 

that might be best. lol

 

what? Who can't make 300whp on 26psi, stock turbo? Show me this person i would like to hit them............. More than once lol!!!

 

I should have worded that differently. They can hit 300, but not much past. Remember, we don't have a "happy" dyno.