Shimless heads?

[BXSS]

Could the turbo be an old school T66?

We were using a T66 (1.15ar e-housing) on the Starlet & ran 9.97s/137ish mph 1/4s @ just 20psi on a 12a Rotary motor.
We got it for free so we used it, we blew it after 2 years of fun & now have a GT45R which is BIGGER.

The Skyline turbos are junk if they are the twin-turbo ones with the ceramic wheels that explode pasrt 14-15psi that I'm thinking about.

I'm not sure what the application is for this motor build (road or drag race) but I also agree with not overrevving the motor if no power will be made @ the higher RPMs.

Now if you will be making power up there (cams, big turbo...) & can run high RPMs reliably then do it, I'm sure someone somewhere is revving a Subaru high.

[evolutionmovement]

But I doubt it would run well at all at low speed and he might have idle issues. The behavior of air at high speeds is different than at low speeds and what works for one won't work for the other. That's why variable valve timing has allowed engines to hit high rpm and still be streetable - they have a set of cam or at least a timing change to account for two rpm ranges (typically high and low). I don't know what's taking so long with infinitely variable valve timing, but I digress as usual. High rpm is more than some lighter rods and tighter valve springs. He doesn't have variable valve timing so I think he'll ultimately be very disappointed after the first couple of acceleration runs. The other thing is getting gearing right so that the next would hit in the high end range as any drop from this relatively narrow band could give you whiplash wvery time you shift. Hesitation, stumble, stumble, stumble, BAM! Lag, lag BAM! If that sounds like it's worth a lot of money to have and watch scooters outrun you from lights on the streets while you wait a minute in a stumbling off-boost engine, trying like hell to breathe right for boost to hit and not having the time or room to even get to that point, then go ahead. But if that sounds pretty pointless, then it won't be worth it. If he was talking a couple hours of f'n around to give it a shot, that would be one thing, but he's talking a lot of time and money.

If you want to experiment, what about a compressed air anti-lag system? It would be pretty cheap, is known to work, and would certainly make you look like a genius at shows.

[tris91ricer]

I'm interested in a few anti-lag techniques, Steve. Got any more info on that? I'd love to hear 'em.

As far as the boosting situation goes, he's talking about a dual intercooler setup. I gave him the WRX TMIC to use, but he also wants to hookup a FM with it as well. I'm not sure if that's been done before, but I can imagine with all the piping that involves, there will be a fair amount of lag to deal with.
Like I said, we'll see.

[evolutionmovement]

It's more than an issue of lag. The airflow behavior at different rpm ranges is independent of boost. Ever hear an old muscle car with a loping, stumbling idle? It comes from the cam that is optimized for high rpm (which in a muscle car isn't stratospheric anyway) and is a sign of how the engine is having trouble breathing right at low end. I think what you're discussing would be far worse due to the head design, displacement, and much higher high rpm range.

The antilag works. I cam up with it years ago, but the Subaru and Ford WRC teams used an almost identical idea for about half a year before the FIA banned it. How well it worked is open to debate, as I could find nothing quantitative other than that it did provide an advantage.

Anyway, you take a compressed air storage tank and you plum it with a tube with a one way valve at the intake and/or attach to the blow-off valve outlet so that excess boost (you could set it so that you have a sort of secondary waste gate that vents excess pressurized air from the intake to the compressed air tank and you'd set the actual wastegate a little higher than you normally would to allow for the extra volume. This really should be done with some kind of control that can constantly manage the wastegate and compressor valve.) But! Very easily done is just to plum off the blow off valve alone and send that to the compressed air tank (the tank can also be manually filled at a gas station or whatever). Hell, you can even hook up an electric compressor to fill the tank. Maybe from an old air suspension car.

So you have this pressurized air. Now you can rig this up in various ways, either by manual switch or by a pressure switch, whatever, but when the system is set to 'run' (you may not want to use it all the time), a low pressure in the intake (turbo lag situation) will cause the tank to start dumping its extra air into the intake until higher pressure (from the turbo spooling) flips the switch that shuts it off. Or you do this yourself, or however you want to trigger/detrigger the system.

Hope that makes sense. I originally wrote it into my book, but took it out. In the book, the system didn't work, but led to active pneumatic aerodynamic aids. In real life, as I later found out, it does work. The difference is the size of the tubing. The real one used what looked like 3" PVC for the tank->intake piping. Intake->tank piping would depend on how you set up the system. If you took excess boost pressure, you would need a large pipe, possibly using the same pipe, but with a valve that would determine if the compressed air would be entering or leaving the tank. From the BOV, you'd have to play around with sizes, but I don't think it would be as critical as long as it allowed the air to exit the intake quick enough to avoid surging the turbo. You'd have to math that out or just use something huge. I don't know what the volume of air/unit time would be. Easiest of all would be to forgo using the waste air (though I think it's cool to be able to use what you'd normally throw away, making the whole turbo system that much more efficient) and just fill the tank with compressed air by an external source. Would probably be a visually cleaner set up, too, if less interesting. Don't know how long you could go on say, a five gallon tank @ 90 psi, but worse case you could always sell it if it doesn't work well or is a c%$# to get to tune right and you're only out the tubing cost. Running the piping out of the engine compartment to wherever you keep your tank (WRC teams used the trunk, I set it in the passenger foot well in the book) - that's on you.

[tris91ricer]

So instead of shooting gas and a spark into the impeller, you're shooting a blast of high-pressure air to overcome the lack of exhaust velocity at that moment?
I understand the previous method of using fuel and spark blows up/shreds impellers.

I also like the idea of using BOV air to re-charge the system. Sounds neat!

[evolutionmovement]

Yes, the air would come in between the turbo and throttle. When the turbo isn't spinning fast enough to supply compressed air, this supplies it from the reserve tank. I envision the tank's dump tube would T off the plastic intake pipe that delivers the air from the turbo to the throttle in an intercoolerless stock turbo car. I'd personally remake a pipe out of thermoplastic using a plastic welder so it looked slick, but I'm in love with this glorified glue gun.

i think I may have discussed this idea ages ago if you wanted to search for something more coherent (or at least more fresh in my mind).

[BXSS]

I still do not know what the application is & agree that for a street app building a motor for a narrow high RPM powerband is silly, but sometimes folks want to do something different/difficult/supposedly impossible.

I know some silly folks who run 1980 vintage toyota 1.8l hemi motors @ over 58psi & 11,000 RPMs some even run these boost/RPM levels on carbs! Two stepping on launch they drop the clutch @ 30+psi & run 8 second 1/4 miles. These cars do not have variable timing or even 16valves, which is why I find them pretty darn amazing.

Our drag car has been datalogged @ 13,800rpm, & can pull cleanly & strongly off its 1500rpm idle but is not a piston motor so it does not count.

Note - There is a boost control system on the market that sounds like what is described above. It uses a CO2 tank & pressure regulator hooked up to the wastgate top & bottom fittings to keep boost @ the target you set on the regulator.
Not sure exactly what is involved in the system because I saw it on a couple cars & the guys who have this oversimplify the system & its components, possibly because my Spanish is so-so.

[555BCTurbo]

Starlets are the shit!!!!


I am planning on building one to run Group 5 Historic in the next couple years...

But with a Turbo 3TC


[/end hijack]

[denver_whitest185]

actually, WRC ST205's came with air injection anti lag from the factory. when activated, it takes the air from the bypass and shoots it into the manifold





however, good luck getting any turbo life out of it. even ball bearing turbos will die within 10k or so. its not ment to be on a street car, and the only reason it was put on ST205s was for WRC rules. i should add that they do not spool the turbo with the injected air, the air is simply to give the raw fuel a way to explode. When lifting off the throttle quickly, the BOV diverts air into the exhaust stream while the computer would add extra fuel and heavily retard the spark timing causing the fuel to be ignited by the late spark while the fuel was being pushed out the exhaust valves. you can also use a standalone to pull this off


Oh, your car will sound like this

http://video.google.com/videoplay?docid ... 3990164610

[555BCTurbo]

My Legacy has spark-based antilag...


http://bbs.legacycentral.org/viewtopic. ... ht=antilag

[BXSS]

3TC = 1.8 Hemi head.

My friend Dyno'ed his @ 469WHP @ 40ish PSI.
He said he had to keep the boost low because it had an ignition based misfire....
He is one of the 58+PSI crowd.

[evolutionmovement]

Yeah, that's traditional antilag. The system I'm describing adds stored boost into the intake. Sounds like what BXSS may be talking about as well, but standard pressurized atmosphere, not CO2. This would be free to nearly free to run once built.