Tech GT Engine Management system from Forza installed in my 308 QV!!

I'm not sure I buy this. I would a agree that it takes energy to get the wheels up to speed, but once at speed no additional energy would be consumed. I would think having the wheels installed would result in a longer spool up time, but not impact that total powered measured by the dyno.

 

Mass takes more power to rotate the higher the rpm goes which is why more power is lost at a higher rpm than at a lower rpm.

Below is a poorly tuned 328 dyno sheet from the most accurate dyno in the world known as a maha dyno. These dynos calculate the drivetrain losses and in this graph are represented by a green line which you can see moves higher with increasing rpm.

The higher the rpm the greater the drivetrain loss.
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Lets see some pics of the rest of the package installed!!

Rick

 

+1. Where are the pictures? Did Forza make a full EFI system kit for you? Or just a spark system and you are doing the rest.

 

It's not the mass that takes more power, it's the friction losses that increase with RPM. Mass takes energy to accelerate, but not to maintain a velocity (assuming a closed system without friction losses). In terms or real world, on the road performance, yes heavy wheels will negatively affect the acceleration of the car. Acceleration is different than steady state power output.

Once a mass is at a given speed, it will keep spinning at that speed with no additional energy input. Conservation of angular momentum is the technical term.

Think of an old steam engine with a huge iron flywheel. It won't rev quickly, but it's peak power output at steady state is not reduced. A 100 HP steam engine does not become a 50 HP steam engine if you double the mass of its flywheel. It's still a 100 HP engine, it will just take longer to accelerate to operating speed. I am making the same argument with regard to chassis vs. hub dyno. You are basically doing the same thing as in my example. You're adding more "flywheel" mass to the system. It won't accelerate as fast (which is what matters in the real world), but if you were to hold 6000 rpm, the power output from the engine would be the same.

I would agree on a chassis dyno you will post lower numbers, but I would argue this is due to friction losses at the tire to roller interface, energy eaten up flexing the tire, wind resistance, slippage, etc., not the added mass of the wheels.

 

exactly. a dyno measures how quickly the wheels can accelerate something, not maintain a speed. If there is less weight for the drivetrain to accel, the accel is going to be more efficient.

 

Hub dynos still measure according to how quickly it accelerates a certain value. While mass vs acceleration makes sense, it does not stand on how a dyno measures power. A Maha dyno measures far more accurately than all and the dyno runs are not just a 'run' up an rpm scale like every other dyno is. Point is: at the hub and at the wheels is not the same thing in terms of when something is accelerating, and most dynos (except maha) measure acceleration.

Another fchatter has a sheet floating around here somewhere that made 210 at the wheels and he was running over 11:1 compression and programmable fuel injection. These engines can make power, but you HAVE to tear into them to do it. Stock components are not going to yield all that great a result. Most US spec QVs make no more than 185 at the wheels, and those are excellent examples in top tune. I don't care what kind of manangement software is being run. 12.5:1 optimal power stoich with optimal ignition timing is what it is regardless of what software is being run.

 

most of the dynojets are inertia based dyno's they calculate power differently than a load base or "brake" type dyno were you can dial in resistance to the drivetrain.

oem all use the load base dyno's and dont monkey around with inertia dyno's at all for they dont replicate real world driving conditions which is crucial to tune a motor correctly. your A/F ratio may read perfectly on a dyno jet and will differ on the road under load.

not that inertia base dyno are toatlly useless but dialing in the mapping on a load base dyno or a laptop while driving the car will give you better results. the load can be intense much like real world running. many years ago ive operated a load bearing dyno. even with a relatively low power vingate car, ive fried tires trying to dial in the loads on the water brake. inertia dynos in contrast are like peddling a stationary bike, once you get them spinning there isnt much resistance and the pedals end up moving the your feet.

typically inertia based dynos will read higher than load dynos. but depending on the input "correction" numbers you punch into dyno machine you can basically cheat the output readings to anything you want.

more importantly the must useful aspect of using dyno is to see what your motor makes before and after the modifications and not to get hung up on specific hp numbers numbers of different motors running on different dynos on different days. you can only compare different motors with any sort of meaningful accuracy with one another if they run on the same dyno and preferable on the same day with same correction factors.

btw dynojets now offer load bearing dyno for there higher end models


my 2 cents

hf

 

great post!

 

Whether or not it makes 230 at the wheels, by replacing the antiquated K-Jetronic you eliminate need for the induction air having to go through the plunger or flapper body which is a very restrictive component in the intake system. That’s were most of the power gains would come from I reckon. Power gains are also made by using the more modern stand alone ecu and injectors not to mention the potential to have better drivability if tuned properly.

 

Completely agree. There's maybe 10-15bhp in removing those restrictions and tuning.

 

I would install a supercharger to make more HP without having to bother with changing anything else in the engine. It seem by far to be the simplest and least expensive method and the engine can easily be returned to totally stock if desired.

 

I suppose if you have to ask...but did we ever get an answer to this question?

Aaron

 

The tec management boxes are a couple k on their own. Doing everything else with the other bits and tuning really adds up. I would say it's a $5k+ project.

 

OK, finally some pictures. Now how about some details. Like what comes in the kit. How long did it take to install, etc.

I assume on the electrical side, it is much like(if not exactly the same as) the XDI install. On the fuel side, it looks like a throttle body extension, custom machined fuel injectors, custom formed fuel rails. Are you using new fuel pump? Did this allow you to get rid of the fuel accumulator?

 

Sounds fabulous and congrats on ironing the thing out. I know how difficult it is once an engine is modified and fuel/spark advance has to be recalibrated. Kudos to you for going pretty much all the way with things!