Turbos making less power down low?
 

Theres been talk about turbo kits making less power down the RPM range before any boost kicks in. I've notice that most Dyno graphs only show past 3k rpm. I hate rumors and when people say "but he said" and "the other guy said"

I'm hoping the turbo tunners will answer this question once and for all.

it all depends on the turbo size, where its placed, piping, and alot of other stuff. But their is a chance of some loss of power due to no boost down low. I would not worry since 3k rpm is really low for our cars, infact if boost kicks in at 3k then thats great.

Dynos starting at 3k RPM does not mean the car doesn't make any power below 3k RPM. That's just when they happen to start measuring.

would love to see a pull that shows stock vs turbo from 0 rpm...

Can this be done?

With a quick high revving engine, 3k RPM is nothing. I think that is actually pretty quick.

My EVO X does not really "kick in" until about 3-3500 RPM either. Feels plenty fast but lack of low end grunt does hurt out of the hole.

Torque is the big thing to look at, hot HP.

This! Everyone always forgets that Torque is what gets you going fast (acceleration) and HP is what lets you be fast (top speed) if that makes sense. For example, a car that runs a quick 1/4 will have lots of torque but not necessarily a lot of HP. However, a car that can run 200 mph will have a lot of HP but no necessarily a lot of torque.

Torque is what moves mass period. Hence the reason my dodge cummins make 650 ftlbs of torque and will pull the hell out of my trailer from stand still. Disconnect the trailer step on the gas truck barley picks up any acceleration.

Have you driven this car the motor doesn't come on till after 3000 rpm whats the point of a turbo spooling up if the engine isn't breathing yet?

When I set my turbo motors up I always want full boost by torque peek. I would say the kit's are doing this quite nicely.

Our cars are super light they don't need gobs of torque like a heavy car does to get the mass moving. The main reason the torque figures are down is due to the head design and the high compression. I would much rather have this bad ass tuned head than some small port high torque non revving head. Kuttos to Yamaha for building us a badass head.

That's because most turbocharged setups I've seen so far - are essentially a competition by tuning shops for top HP. So they pretty much don't care about torque down low, cause it will hurt the end-result HP number. Very rarely will a tuner produce a DD-friendly turbo setup on his/her own, unless specifically paid by the customer to research that.

Why current setups lose torque in the low RPM range - I don't know. The "dyno starts at 3k" is a lame excuse. Dyno of a stock car also starts at 3k generally reads higher.

2-4k RPM range is imporant for DDing these cars.

PS: "moving mass" is work. Amount of work per second = HP.

I disagree. I know that the AP kit was designed to spool a bit latter and have a bit less at the low end (not over stock but over what a different turbo would have made) because Don was worried about things breaking if there was to much low end gain. I read that on here somewhere anyway... Seems like the turbo was selected with the daily driver in mind.

On another front, these shops know that most people will not be turbo charging their FRS. And even those that do are not building race cars but rather fast street cars. From what I have seen they build their products with this in mind. The "most HP" competition you see is just marketing and a way to test the motor as well as their products.

My 2 cents.

Dynos I've seen - are producing less in the <3k RPM range. Not sure how the concern of something braking is relevant there. If it's just the dyno start at 2.5k that's affecting things - then they have to start it sooner. 3k is 6th gear @70mph. If there is a nice torque gain there, I'm sure people too lazy to shift in traffic will appreciate it.

That's one thing i've noticed as well torque and hp figures in the low rpm's aren't impressive. Thats why i'm hoping a smaller turbo or supercharger kit will come out thats got more power early in the rev range i don't care about 300hp at 7k rpm

Yamaha had no involvment on the heads of Subaru's FA20, Toyota's direct and port injection (D4-S) was their contibution.


And as for turbo power down low? Check out the FB20 DIT in the JDM legacy (295hp 295tq) :
http://blogs.insideline.com/straight...it_power_b.jpg

:wub: seeing that in a BRZ(with a tune!) :party0030:

Hoping for a roots type SC kit or fast spooling turbo kit as well. Currently living at extremely high elevation (over 6000 ft.), and with the consequent power loss this car is a complete dog in the low end.

not sure what newton meters converts to lb ft but i like that flat torque curve.

you can have a turbo make power low. like said, they are just reading at 3k and up. a factory sti boosts pretty low, you can have boost pressure and torque at about 1500-2000 RPM if you wanted...it just takes the correct setup.

since the fr-s revs higher than a normal subaru would, i would rather have a well performing mid range-high end turbo. boost by 3k is awesome.

Love the new STI turbo. A friend of mine just got a new one and there is no lag whatsoever. It's great for this area of Colorado.

Twin-scroll anyone?

Am I the only one that kinda likes turbo lag?

In my Supra, I didn't get out of vacuum until about 3.5k and I didn't make all 21psi until about 5k or so (IIRC).

I LOVED how docile the car was in daily driving. No whistling, no blow off, no drama. If you wanted to boost, you dropped a gear and away you went (It was a BoostLogic Auto, so that was as easy as putting your foot down). It was great for sneaking by police, sneaking by Civics (:D), and sneaking by the president of the homeowners association coming back home late.

On top of that, there's no surprises when going from light to light, because you're head doesn't get thrown back at 3k RPM. If you had a system that made boost that early, you would be in for a jerky(ish) ride.

And of course, if you go to a track or a drag strip, you'll be kinda out of puff in the top end if your turbo is sized and set up for power early on.


But, there's twin charger setups... :bonk:


Just my $0.02.

Err stock turbo Supra makes like 10psi at 2krpm?

Considering he said BoostLogic Auto i doubt it was a stock turbo on that Supra :party0030:

A stock TT Supra running sequentially might start spooling at 2k, but a big Single sure doesn't! ;)

Yes, yes you are. You are the only one <Jeremy Clarkson>in the world.</Jeremy Clarkson>

Read my mind! its like mechanical foreplay

I think its a supra owners thing... Ive actually been thinking the same thing. If the car feels like stock power until 3-4k thats fine by me as Id prefer it to be very docile until you slam on it.

I wonder if everyone that prefers the lag feeling also likes the quote to walk softly but carry a big stick :0

I can't say I've heard that before, but I like it!


Perhaps it is a Supra owners thing...

Other sources have said the heads were developed by Toyota/Yamaha, just like in previous Toyota engines. And its been known since before the car was released.

I can't think of another subaru motor that had a head anything like the FA20. The head was co-developed by Yamaha/Toyota and Subaru, but the design features are definitely Yamaha.

You are simply making things up, I challenge you to give me one RELIABLE source. And this is not a 'previous Toyota' engine... the car, as a piece of craftsmanship, is a Subaru.

Yahama involvement was nothing but an old-school rumor. :thumbdown:

Hell, i love the small low-end.... Its nice, as said before, for sneaking by anyone. This car was made to keep power up top...

Do you have a source that says it is a subaru head, designed from the ground up from subaru? Perhaps you are right, but hey, the transmission and rear end are all Toyota parts. What's so hard to believe about the heads having some Toyota development?

The ports, lifters, rocker assembly, all scream Yamaha to me. Perhaps Subaru just took all their good design queues.

Yamaha has designed a lot of oem head for different manufactures. 3SGTE head for one, a very good Toyota head. Why would this be hard to be leave. This car is a hodge podge of different part's. I don't care who built what. The characteristic of the motor speak for it self. You can't reinvent the motor with a turbo period.


Secondly late boost on a high compression motor will save it from early torque detonation. This and good control over the direct injection timing.

I hope it's true because Yamaha gets it done.

yeah yeah I know. I was referring to you saying that if a turbo spools under 3k, it would be jerky for daily driving.

I guess in that regard, you're right... Although, 1-3psi at 2-3k RPM is kinda insignificant as well.

If somebody make a turbo that made a bar of boost at 2k RPM, that would certainly be jerky in DDing. Although, I'm not sure that can even be done... :iono:

My tuner is working on power down low. Also the cams apparently are a bitch to tune and require extra hardware or software. Don't quote me on this.

Sent from my Galaxy Nexus

I do not like turbo lag. However i do not think that when i would use that turbo (autocross, track days) that i will be spending much, if any, time below 3k rpm. I have autocrossed the car and it is easy to keep above 3k rpm, even though it was a tight course.

The FB20, the platform for the FA20 architecture, shares itself with the FA20 DIT which is a modified turbo platform of that similar engine. So indeed it can be done, and done well! 295tq 2000-4800rpm must be awesome.

Once again Yamaha has had nothing to do with this vehicle or its engine.

http://blogs.insideline.com/straight...it_power_b.jpg
That's what I call "massive turbine restriction", not "great torque". There are better ways to get that kind of boost, namely supercharging. A turbo's strong point is its efficiency when it has a nice big free flowing turbine, aka not low end.

If ~300tq by 2k isn't 'great torque' than what does that make the 151tq from the FA20?

Turbine restriction?

It's great torque thanks to great turbine restriction. Well, at 2k that engine is doing okay, but that flat line is because the wastegate is blowing off a massive amount of pressure to prevent the engine from blowing up. Aka, wasting a lot of power. At that point, a supercharger is the more sound option, although I do admit that they're a little more difficult to design.

I guess the appeal of a turbo is that you only need to worry about plumbing and you can control the boost pretty easily, but take transient response into account and it makes very little sense the way most turbo setups are done. Sure, they get the job done, but not in the best way.

I suppose 'the best' is relative to the user and plans... its a lot more fun swapping tunes compared to pulleys; and the aftermarket/OEM support for these turbo systems keeps most of it reliable/predictable.