So Im looking around at the dyno charts on the ScionSpeed website today. Im noticing that on all the dyno charts the air fuel is all over the place. I think between the three charts I looked at the air fuel drops below 12:1 once. In some area's they are close to 14:1. These are obviously NOT pump gas charts. What numbers can we expect on pump gas? Ya know, for those of us that can't afford to run race gas all the time.

It appears as well that there is some detonation at the top of the chart on the 426 run. I noticed on the end of your 426 dyno video that the car is smoking white at the end of the pull. Whats up with this? Oil smokes white??? With the extremely lean a/f's that im seeing, could there be some damage? Im not impressed with the tuning on this car at all. I'd like to see a pump gas pull with a/f's in the 11.2 range all the way across the board.

Im just looking for some answers here. Here are the links right off scionspeeds website so everyone can see what im talking about...

http://www.scionspeed.com/images/dyno327.jpg <--327 pull
http://www.scionspeed.com/images/dyno353.jpg <---353 pull
http://www.scionspeed.com/images/dyno426.jpg <---426 pull

The dyno pull video can be found in the media section of the website as well.

 

hrmm.. doesn't seem TOO eratic but i'd be interested to see what would happen when you push that setup

creeping up to 14 isn't good

 

Even on VP103, which is what I believe they are running. high 13:XX a/f is really pushing it. I guess in a way it could be a testiment to the strength of the 2AZ. At the same time, I'd like to see a good a/f chart for the production kit.

 

no matter how good the internals are, if the headgasket blows, you're out of luck

 

They have multi layer steel gaskets from the factory. Im not worried about that as much as detonation killing the rings or worse.

On those maps, pump gas = KABOOM. Even on race gas that engine wont last long.

 

Actually, antifreeze smokes white. Oil comes out grey. I haven't seen the videos, but if it is indeed white smoke, I'm guessing by by to that head gasket...which means the bearings are now coated/varnished, which means it'll be time for an engine rebuild before too long

 

Well white smoke is usually sign of head gasket leaking. I blew the head gasket on my turbo 02 Civic turbo so I definately know about the tell-tale sings haha...

A simple fix to this leaning out issue could be a fuel return conversion, larger injectors, and an FPR. Of course you need a fuel computer but Scion Speed already gives you that.

 

White smoke, grey smoke, its to quick to tell. In either event, somethings not right. The answer to the leaning out issue is in the tuning. As far as I know, they are on the same setup with the 350something run as they are with the 426HP run. If it were maxing out the fuel setup the first time, it never would have lasted for the 426 run.

In either event, I still want to see a good pump gas A/f chart. Cause those are crap.

 

P.S. The SRT's are making well over 400 whp with a returnless system.

 

Just looked at the video....that is definitely white smoke. The fact that they panned away from it, almost as soon as it started, confirms something undesireable is happening.

 

i've seen steel gaskets blow as low as 8psi. so you may think thats the saving grace but i would not be surprised if you still blew a headgasket.

i would hope it would hold up but i'd rather cover me **** and run at 12.5 AF and 93 octane

 

Hey guys.

When we posted this dyno we posted an explanation on it explaining that lean area. Basically when we did that run everything was pegged, the injecters where at 105% duty cycle (yes it said 105% lol), and the fuel pump was dropping pressure.

So we are working on a return line kit, that is boost sensitive for you guys, as well as a way to run larger than 750cc injectors, which right now is the largest you can run on this ecu.

But you guys are correct running that lean all the time would be bad for the engine.

These engines also like the AFR's at around 13.5:1, this is where it makes the most power. 12.5:1 to 13:1 is very safe for these engines. 11.2:1 is way too rich for this car.

No, the head gasket is not blown. That puff of smoke at the end is coolant. At these boost pressures and HP levels, the head actually started lifting off of the block This problem is easily fixed with a good set of Head Studs instead of bolts, which we will also offer to you guys. That is also why we run 15psi at the track instead of 17psi.

This car is driven daily, people come by our shop almost everyday to see it, and you can see it driving around Miami/Ft.lauderdale at any time, we use it to pick up and deliver parts!!! Its in perfect running condition.

Jayson

Jayson

 

for all intensive purposes, lifting the head off the block, and blowing a head gasket produce the same result: coolant is leaking where it should not be ( in this case the combustion chamber). if enough coolant is getting (or has gotten) past the head/gasket, it'll mix with your oil. When that happens, your bearings will get coated and you'll end up frying your bottom end.

Also superheated coolant can eat aluminum heads and engine blocks requiring VERY costly repairs. haven't paid much attention to our block/head....so if it isn't Alum, then I guess that last part isn't a concern.

 

good to know Jayson.
don't blow up your car LOL

 

Maybe I can shed some light on this subject. I dynoed my old boosted Z24 cavalier several times, and was given this information from a the guy that not only runs the dyno, but has built street/race motors from the old muscle cars to the latest Honda motors. An air fuel ratio between 12-14 is good. Anything 12:1 or less is running rich. Anything 14:1 or greater is getting lean. Leaner=more power (sometimes), but creates a bigger chance to blow you motor if something goes wrong. Richer= less power (for the most part) and gives you that "safety area and bad gas mileage." I believe, if I remember correctly, that 14.7:1 is the rate at which all fuel is consumed, but leaves no area for imperfections at all. A slight clog in an injector at this point, a faulty F.P.R., or any quirk in the fuel system would equal a blown motor. The hard thing about tuning is to find the happy medium, and 13.5:1 fits right in the middle. I would hope that they have fine tuned their product just a little better, but that a/f ratio isn't a bad starting point at all!

 

i'd rather see a commercial turbo kit be at and around 12.5

if they sell a turbo kit thats running close to 14 all the time it will shorten the life of the engine and give turbos and the platform they're turbo'ing a bad name.

 

I agree... pump gas, outside temps,etc... I'd rather see a street, daily driven F/I car running between 12 and 13. Gas is cheap when compared to the cost of rebuilding an engine.

 

I believe you guys are getting a few things twisted here. AFR is only part of the equation. What do I mean? Timing is the other halve you can run 15.1 all day long if you pull enough timing to compensate. This is not how we tune cars but you can do it. Hell Mazda Speed does it on there protégé.

A Forced induction car has completely different AFR than a NA car. If you all are seriously running in the 13-14 range on pump gas in anything with a aftermarket turbo kit on it and pump gas you are in the wrong. This is my professional opinion and I tune cars everyday. I understand Scion Speed was at the end of there fuel system and that is fine. But to the other guys on the board if your tuners and tuning your cars in that range you are playing with fire and the first hot/humid day you will get burnt.

Our turbo kits come with a 11.2-11.5 AFR not only will this assure a long happy boosted life for your brand new car. But this will also assure that regardless of Air temp we can have a safe tune. Hell are test car in Cali. Started getting 12.1 AFR and we postponed the release of our kits because of it. Custom tunes you can play in 12 area but with a default tune it needs to be in the mid 11 range with a conservative amount of timing. Hell it the TC ecu sees more than 13.8.1 the car pulls timing. Some may call us conservative but we are making good power with no issues and we beat the hell out of our cars.

 

the ECU is that conservative? that kinda sucks

 

You've got bigger problems then that because the emanage is really only good for about 550CC injectors. Not to mention that the stock fuel rail can only flow enough to support 720's. AEM hasnt released a stand alone yet, Motec has one that is in the 4K range. So unless there is a cable throttle body conversion somewhere in the works, what are your plans?

Are you running the stock fuel pump right now?

13.5:1 air fuels are perfect, for a naturally aspirated car. I seriously dont believe that you can pull enough timing to run safely over 12:1 and still make good power on pump gas. Can we see some pump gas dyno charts?