Patrick's build thread. (IT RUNS!)
03-20-2014, 11:22 AM
#886
Nordschleife Master
The "ramp rate" is I suppose the Proportional and Derivative gains of the PID settings controlling the boost delivery in closed loop. They can be a pain to get right when using a wastegate spring that is "too stiff", against which the solenoid won't be able to work with enough finesse to smoothen the boost curve to just let the PWM algorithm to work as it should.
Since loading a turbo on a dyno will never put as much load on the turbo as it would on the road, at least during the boost build-up rpm range, it's going to be difficult to get the "best" PID settings on the dyno, and even when using a MAP-driven ECU it's possible you might also run slightly lean on the road where the turbo spools before reaching peak boost, if you tuned for a targeted AFR on the dyno.
An ECU log from the track will be far more accurate than a dyno run to show how a turbo spools in real driving conditions, if you have any to show.
In my experience at least.
Since loading a turbo on a dyno will never put as much load on the turbo as it would on the road, at least during the boost build-up rpm range, it's going to be difficult to get the "best" PID settings on the dyno, and even when using a MAP-driven ECU it's possible you might also run slightly lean on the road where the turbo spools before reaching peak boost, if you tuned for a targeted AFR on the dyno.
An ECU log from the track will be far more accurate than a dyno run to show how a turbo spools in real driving conditions, if you have any to show.
In my experience at least.
What you need to do is to tune the engine for all the load vs rpm situations you can find on the road/track. That's why it's not enough with just a high gear tune on the road nor a single sweep on the dyno either. Because then you haven't tuned the map for coming out of a corner in 2nd gear flooring it.
And if you do a load dyno you can load the engine and turbo way harder that you can do on the street. It's just a matter of dyno and you operate it.
Comparing boost vs rpm isn't really relevant on dynos as loadings and dyno types differ so much. Only a comparison in the same gear on a flat road makes sense. But another point is that boost vs rpm is only a valid comparison if the engines are similar (same displacement, head, cams etc). Otherwise it's only torque vs rpm that is relevant. Well to be more exact it's only the average power during the used rpm range that is relevant as a higher revving machine can have less peak torque on the dyno chart but higher torque at the wheels..
03-20-2014, 11:48 AM
#887
Rennlist Member
All of you simplify this too much when you refere to "on the road" as a given situation. Tuning on the dyno is just as relevant as tuning in 6th gear going uphill on the road. In real life you encounter all kinds of load scenarios, from 1st gear WOT going downhill to top gear going uphill. You will see boost vs rpm logs extremely different.
What you need to do is to tune the engine for all the load vs rpm situations you can find on the road/track. That's why it's not enough with just a high gear tune on the road nor a single sweep on the dyno either. Because then you haven't tuned the map for coming out of a corner in 2nd gear flooring it.
And if you do a load dyno you can load the engine and turbo way harder that you can do on the street. It's just a matter of dyno and you operate it.
Comparing boost vs rpm isn't really relevant on dynos as loadings and dyno types differ so much. Only a comparison in the same gear on a flat road makes sense. But another point is that boost vs rpm is only a valid comparison if the engines are similar (same displacement, head, cams etc). Otherwise it's only torque vs rpm that is relevant. Well to be more exact it's only the average power during the used rpm range that is relevant as a higher revving machine can have less peak torque on the dyno chart but higher torque at the wheels..
What you need to do is to tune the engine for all the load vs rpm situations you can find on the road/track. That's why it's not enough with just a high gear tune on the road nor a single sweep on the dyno either. Because then you haven't tuned the map for coming out of a corner in 2nd gear flooring it.
And if you do a load dyno you can load the engine and turbo way harder that you can do on the street. It's just a matter of dyno and you operate it.
Comparing boost vs rpm isn't really relevant on dynos as loadings and dyno types differ so much. Only a comparison in the same gear on a flat road makes sense. But another point is that boost vs rpm is only a valid comparison if the engines are similar (same displacement, head, cams etc). Otherwise it's only torque vs rpm that is relevant. Well to be more exact it's only the average power during the used rpm range that is relevant as a higher revving machine can have less peak torque on the dyno chart but higher torque at the wheels..
03-20-2014, 12:04 PM
#888
I agree with all you said Duke, but I thought it was clear from my post that "on the road" was meant as "not to waste time on the dyno tuning for areas you never reach on the road"?
Sorry if that's not how my previous post came across, I didn't mean to "simplify" the tuning process, but just to avoid make it sound more complicated that we all know it already is.
Sorry if that's not how my previous post came across, I didn't mean to "simplify" the tuning process, but just to avoid make it sound more complicated that we all know it already is.
05-22-2014, 09:10 PM
#889
Rennlist Member
Thread Starter
A few updates occurring right now.
We discovered the last time out that we were running out of front brakes. They were Big Reds on 2 piece floating/slotted 332x32mm rotors. I had purchased a 2nd hand set of 997 Cup Calipers that were repainted and refurbuilt in the US some years ago. Due to various reasons they hadn't been sent down to me until recently. I had also wasted quite a lot of time and money trying to source some larger 350mm rotors to fit with the Mo30 uprights but that just didn't work.
So we then decided to go with the later sized Cup rotor of 380mm / 15" but that was going to be a really tight squeeze in under our 18" wheels. Finally we decided on ordering some custom rotors and hats from Coleman Racing which were 375x32mm. These finally arrived (although they made a mistake when converting mm to inch which resulted with the inner face being 9mm shorter than we ordered) and we went to fit the Cup Calipers. Unfortunately they had been put back together incorrectly which resulted in the Ti pistons being damaged. Further investigation shows that it would cost something like $1500 to rebuild both of these calipers and also the more I read, the more I found out that the Cup Calipers aren't viewed as a true race quality version. Race teams have to run them but they probably toss them away after each meeting as they're subsidised when buying them.
So, after more frustration and wasted time we decided to ditch the Brembos and go for some 6 piston Alcon calipers and make up the adapters here. These are the same calipers that were used on the Aussie Supercar V8's for many years so they are well regarded as being of stout quality. Interestingly when we compared the previous rotor and caliper vs the new larger setup, the new one is slightly lighter which is a bonus! Another thing was that these calipers have much larger piston area so we've had to change the master cylinders to adjust for this. The Cup calipers have 28,30,32mm pistons vs 30,35,38mm pistons for the Alcons. Which also means that the piston area covers all of the pad. Incidentally I had also bought 3 sets of pads to work with the Cup calipers so have learned that it is possible to cut them down to fit the Alcons but Paul will be coughing up some interesting substances today!
We discovered the last time out that we were running out of front brakes. They were Big Reds on 2 piece floating/slotted 332x32mm rotors. I had purchased a 2nd hand set of 997 Cup Calipers that were repainted and refurbuilt in the US some years ago. Due to various reasons they hadn't been sent down to me until recently. I had also wasted quite a lot of time and money trying to source some larger 350mm rotors to fit with the Mo30 uprights but that just didn't work.
So we then decided to go with the later sized Cup rotor of 380mm / 15" but that was going to be a really tight squeeze in under our 18" wheels. Finally we decided on ordering some custom rotors and hats from Coleman Racing which were 375x32mm. These finally arrived (although they made a mistake when converting mm to inch which resulted with the inner face being 9mm shorter than we ordered) and we went to fit the Cup Calipers. Unfortunately they had been put back together incorrectly which resulted in the Ti pistons being damaged. Further investigation shows that it would cost something like $1500 to rebuild both of these calipers and also the more I read, the more I found out that the Cup Calipers aren't viewed as a true race quality version. Race teams have to run them but they probably toss them away after each meeting as they're subsidised when buying them.
So, after more frustration and wasted time we decided to ditch the Brembos and go for some 6 piston Alcon calipers and make up the adapters here. These are the same calipers that were used on the Aussie Supercar V8's for many years so they are well regarded as being of stout quality. Interestingly when we compared the previous rotor and caliper vs the new larger setup, the new one is slightly lighter which is a bonus! Another thing was that these calipers have much larger piston area so we've had to change the master cylinders to adjust for this. The Cup calipers have 28,30,32mm pistons vs 30,35,38mm pistons for the Alcons. Which also means that the piston area covers all of the pad. Incidentally I had also bought 3 sets of pads to work with the Cup calipers so have learned that it is possible to cut them down to fit the Alcons but Paul will be coughing up some interesting substances today!
05-22-2014, 09:57 PM
#891
Rennlist Member
Thread Starter
A further change to the car involves the front sway bar. Due to changes we are going to be making to the splitter we have to make room. One of the things that had to move was the front sway bar. So we've made a pretty trick custom setup which has it positioned behind the front Axle line. In addition we get less drag with it more out of the airstream too. There are blades on each side of the cromoly bar and it will have in cabin adjustment via the control unit pictured. Both these new additions plus a new wider version of the front splitter with new end plates (all the dive planes have been removed) will be tested this weekend at the track.
The next steps will be to shorten the radiator from the base upwards, change the p/steering pump to electric and convert the large air to oil cooler to a water to oil version. Both these will be moved from the front of the car. What we are chasing is better front down force and to do this we have to make significant changes to the splitter and also reduce frontal drag. Clearly the rear wing is overpowering the front and we are concentrating on removing as much underhood pressure to do this. The front of the rocker panels have been modified and we'll be making more changes to increase the release of this pressure. Aero is way more important than extra ponies at this stage. Amazing how some apparently minimal changes make a difference too. Angles of vents, panel gaps etc...Aero is King!
The next steps will be to shorten the radiator from the base upwards, change the p/steering pump to electric and convert the large air to oil cooler to a water to oil version. Both these will be moved from the front of the car. What we are chasing is better front down force and to do this we have to make significant changes to the splitter and also reduce frontal drag. Clearly the rear wing is overpowering the front and we are concentrating on removing as much underhood pressure to do this. The front of the rocker panels have been modified and we'll be making more changes to increase the release of this pressure. Aero is way more important than extra ponies at this stage. Amazing how some apparently minimal changes make a difference too. Angles of vents, panel gaps etc...Aero is King!
Last edited by 333pg333; 05-23-2014 at 03:32 AM.
05-22-2014, 09:58 PM
#892
Rennlist Member
Thread Starter
05-22-2014, 11:23 PM
#894
Rennlist Member
Thread Starter
Pic of brakes under 18" wheels.
Last edited by 333pg333; 05-23-2014 at 03:33 AM.
05-23-2014, 12:22 AM
#897
Rennlist Member
How much extra does the new sway bar setup including mounts and weld in plates weigh compared to the (somewhat flimsy) stock setup? Seems heavy and complex. I count 8 heim's, two radial bearings and a substantial amount of steel plate. I assume mounting plates are 1/4" or maybe 3/16" hot rolled given the substantial forces seen with the high sway bar rate.
05-23-2014, 12:54 AM
#898
Rennlist Member
Thread Starter
Thanks Sid. Right back at you. 
Open class Paul. Think I remember that car.
Oh God yes, much heavier than the stock piece I'd guess but it's infinitely more adjustable and has been put there for the reasons already stated. Bear in mind that this sort of setup isn't totally unusual for certain spec race cars. It's complex because of the location, not out of choice. I can assure you that I'd prefer to be spending this money elsewhere. 
How much extra does the new sway bar setup including mounts and weld in plates weigh compared to the (somewhat flimsy) stock setup? Seems heavy and complex. I count 8 heim's, two radial bearings and a substantial amount of steel plate. I assume mounting plates are 1/4" or maybe 3/16" hot rolled given the substantial forces seen with the high sway bar rate.
05-23-2014, 03:28 AM
#900
Rennlist Member
Thread Starter
Whoopsy...yes, water to oil. That's what you get for typing at work while you're on hold! ;-)