just did a 2 second comparison to the XRT and me housemates Skyline R34..

XRT first gear im not even hitting max boost from a stop start with no clutch kicks or anything to get the revs up quicker..

Skyline R34.. boost starts bout 2.5k-3k, and max's out at 4k in first.. (running 8PSI)

the spooling time i believe is too long, sure there is 4PSI difference between the 8PSI (stock) in the skyline and the XRT, but spooling shouldnt take that long..

Quote from Shinanigans :

My RX7 comes onto boost fairly quickly with the stock turbo, even though i think they're quite large for a stock unit (Hitachi HT-18S). I would be well into the full 10 pounds of boost by the time 2500rpm came along. I haven't even noticed the speed increase of boost from 0-2500rpm though.

you 100% sure on that? when mine was stock it would reach peak boost psi of 6 by about 3000rpm, to reach 10 it takes until about 4000rpm...

From memory, yeah. It's been 2 years since i've driven the car though.

If i had to give leeway i would say a maximum of 3000 rpm to hit full boost.

I think consideration has to be given to the fact of how much is required for the CFM requirements of an engine, maybe this is where LFS is off.

An SRT4s 2.4L running roughly the same pressure as the virtual XRT gives almost the same power per displacement, except the SRT4 has a torque peak all the way from 2200-4400RPM (Chris correct me if I'm wrong). None of the turbo'd cars in LFS feel very "torquey" which I think is a bit sad considering they're not 700HP 9000RPM beasts, they're road cars.

Quote from Ball Bearing Turbo :

I think consideration has to be given to the fact of how much is required for the CFM requirements of an engine, maybe this is where LFS is off.

An SRT4s 2.4L running roughly the same pressure as the virtual XRT gives almost the same power per displacement, except the SRT4 has a torque peak all the way from 2200-4400RPM (Chris correct me if I'm wrong). None of the turbo'd cars in LFS feel very "torquey" which I think is a bit sad considering they're not 700HP 9000RPM beasts, they're road cars.

You are close about the torque Jeff. Here is a quick dyno http://www.mopar.com/street/products_srt4_stage1.htm. I get at least 250 pounds of torque from 2400-4400. I agree that the road cars in LFS don't have enough torque.

Pls stop knocking SRT's until you have driven one. The engine in them is phenominal, try to find any other engine that produces these kinds of power curves from the factory. It's NOT a neon, trust me, the only cars out there that can beat it in either cornering and accel in the states is the viper and the vette. Even the carrera4S with the tiptronic tranny isn't safe, look at the info for yourself online. 1/4 mile in mid 13's, the ACR will do the skidpad in the low .9's 60-0 110 feet 0-60 in 5.3 seconds. Top this with 30 MPG you cannot beat it. Sure it's FWD, and sure it might look kinda like a neon, but it will kick your ass. We want to use the SRT 2.4 for compairison because that is what the game runs for an engine, with it being turbo'd. We are not talking about a wankel engine that can create tons of revvs, they are totally different engines. Though if I were racing I would almost want one, they just keep making more and more power the higher the revvs and the power curve is relatively flat with the engine being upgraded.

back onto topic:

Shim one reason why the boost came on slow was maybe the ECU was limiting it? Another thing that brings the boost up slow is running low boost pressure, the higher the boost the faster the spool.

those modded ricer generation supras??...from the vid clips ive seen of them on streetfire.net...the stock turboed ones...seem to accelerate fine...but all the garrett T4 and other style...only hit full boost at almost the redline limiter...would that be the engine not makin enough exhaust until full rpm is reached??

Well I am DLing the editing software so I can stabilize the video, have my camera mount set right, video camera works, now I just need proper lighting I think I will wait until tonight to make the video, that way the gauges are easier to see. This week I "should" have this done, sorry for the delay, funding requirements have delayed this project considerably.

Excuses

Ok here comes for the next barrage of excuses. I updated my bios, forgot to change my setttings in the bios and I spent the remainder of the day trying to remember how to to delete every driver in use and not in use on my friggen system, one good thing came out of this is my computer runs faster again =). Then I had to get my firewire port working, only to find out that the resolution sucks on the camera and I can only capture in 5 second segments... I have to go back to the drawing board and figure out how to get good quality video.

Did a 5th gear up a hill test and noticed that my boost actually starts coming on at 1500, it's linear up to 2300 when I get full boost. I will work on getting a better quality video and see if I can get the software to capture more than 5 seconds at a time with firewire.

Excuses





Actually I was thinking of you this week as a navigated the most beautiful area in North America, and maybe more - Beautiful British Columbia, luckily I live only a hour or two from the province so vacationing is easy....

Back on topic, I was pondering how your car would perform on those twisty mountain roads and up the hills. I pondered being able to "Torque" my way up hills with that boost comming on almost for the entire powerband. When you do get the camera going some videos of different conditions like that would be interesting.

If you're travelling in a strait line at say 120k, with your right foot in one position, what happens boostwise if you DON'T move your foot but begin to climb a fairly steep hill?

the onset of boost is determined by the amount of air flowing into the engine - the airflow doesn't change if your throttle doesn't change, the speed just drops off
in situations where boost is developing, (more open throttle positions) you'll get more boost (below any sort of max limit) for a given rpm uphill, because it has more time to build.

Yeah I figured nothing would happen, BUT....

I was thinking perhaps some strange thermodynamic things might happen causing the engine to output more heat under that condition or something dumb.... Not really thinking much before posting unfortunately, my brain is fried from driving all day. I was somehow thinking that exhaust temperature would rise under increased load like that but if throttling remains constant nothing should really happen... So... never mind

lol

Edit:

Upon some further (albeit minor) contemplation, wouldn't combustion chamber temperatures rise since the same A/F ratio would be used (same throttle position) while the engine decreases RPM due to load? The ignited mixture would remain under higher pressure (& generate more heat) for a longer period before being released into the exhaust manifold (& thus cooled) since there is less time per cycle at lower RPM....

Quote :

Upon some further (albeit minor) contemplation, wouldn't combustion chamber temperatures rise since the same A/F ratio would be used (same throttle position) while the engine decreases RPM due to load? The ignited mixture would remain under higher pressure (& generate more heat) for a longer period before being released into the exhaust manifold (& thus cooled) since there is less time per cycle at lower RPM....

No the temperature would not change drastically. This is because of the way the car is tunned. In HighLoad:Low Rpm situations more fuel is injected and Ignition timming is reduced to something like 2 degrees before top dead center.

Is this universal???

What is the point of running rich with almost no advance at low RPMS?

Someone explain this further please.

well the combination for more fuel no advance is not determined by one factor

the reason for more fuel is because there is alot of Air still entering the engine "LowRPM:HighLOaD" if u injected same about of Fuel as "LowRpm:LowLoad" it would be very lean.

Timming advance is determined by engine speed and the mixture.
More air Less timming
More engine Speed equals more timming

SO in that scenario u have alot of air(less timming) and low Engine Speed(less timming)

Well I tried to keep my foot steady while going up a hill, I was at 20 pound of vacuum and it would float maybe 1/2 pound between going up and down. Another note about mountain driving, I have not found a hill yet that I have had to downshift to make it up going the speed limit, we have some decent hills here too, I would say over 20degree incline on the backroads.