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The more you preload the wastegate actuator, the more you limit the wastegate opening. That’s why the boost increase, because it barely opens.
I don't know if it limits the wastegate opening that much but is that such a bad thing? I mean if your vehicle has been tuned for it?
 

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16 ST, 93 oct, FRPP, RS ac K&N filter, Forge FMIC, Mountune Recirc, CNT cat, 3" pipe, Steeda RMM
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Discussion Starter · #44 ·
I know we got off topic a bit, but I watched a couple of episodes of engine masters that are eye openers with regards to 3" vs 2-1/2" exhaust, crunch bent vs mandrel bent, through muffler vs reverse flow and expensive vs cheap mufflers, running straight pipe, etc. The only downside is you need a subscription to motortrend to watch them. Spoiler alert though... No back pressure is best, but it makes negligible power differences with all the combos unless you're well over 500 hp and chasing down minimal gains. I'd still like to get a better downpipe than the stock one but not expecting much of a difference perhaps a little more efficiency.

As for the waste gate preload, I think I'm going to try it to see what it does. Seems like the worst that can happen is that it runs out of air flow at higher rpm and I'd need to put it back to stock position.
 

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I know we got off topic a bit, but I watched a couple of episodes of engine masters that are eye openers with regards to 3" vs 2-1/2" exhaust, crunch bent vs mandrel bent, through muffler vs reverse flow and expensive vs cheap mufflers, running straight pipe, etc. The only downside is you need a subscription to motortrend to watch them. Spoiler alert though... No back pressure is best, but it makes negligible power differences with all the combos unless you're well over 500 hp and chasing down minimal gains. I'd still like to get a better downpipe than the stock one but not expecting much of a difference perhaps a little more efficiency.

As for the waste gate preload, I think I'm going to try it to see what it does. Seems like the worst that can happen is that it runs out of air flow at higher rpm and I'd need to put it back to stock position.
Mine runs fine with the waste preload fully tightened. Just don't do it until you're ready to install a tune that accommodates for it.. and I'm running a two and a half inch cat back as I didn't want the drone normally associated with the 3-in. But yes you don't need any back pressure the turbo gives you all the back pressure you need.
 

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Discussion Starter · #46 ·
Mine runs fine with the waste preload fully tightened. Just don't do it until you're ready to install a tune that accommodates for it.. and I'm running a two and a half inch cat back as I didn't want the drone normally associated with the 3-in. But yes you don't need any back pressure the turbo gives you all the back pressure you need.
What do you suppose the wastegate preload adjustment would do with the FRPP tune I'm running without changing the tune? Thx
 

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I don't know if it limits the wastegate opening that much but is that such a bad thing? I mean if your vehicle has been tuned for it?
After removing the stock turbo from my car, I adjusted the WGA to see the dynamics of the preload using a bicycle tire pump. The actuator rod has a range of motion, when you preload it shortened that range by the amount of the preload . Since the rod is attached to a level to rotate the wastegate cover/plug. If you tune for this event to counteract the ill effects, the turbo may live up to certain point depending how efficient is the tune. You are increasing the turbo bottleneck effect forcing it to over speed to counteract the increased back pressure. If the back pressure get to the point that the plasma like heated exhaust reenter the combustion chamber igniting the fuel before the spark causing detonation, It will be a sad situation. If you add preload you must tune for it.
 

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What do you suppose the wastegate preload adjustment would do with the FRPP tune I'm running without changing the tune? Thx
FRPP is basic, and probably won't make much change, essentially being a stage 1 torque tune.

I would be more concerned with it not compensating properly for any extra PSI and you not being able to adequately monitor it.
 

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I know we got off topic a bit, but I watched a couple of episodes of engine masters that are eye openers with regards to 3" vs 2-1/2" exhaust, crunch bent vs mandrel bent, through muffler vs reverse flow and expensive vs cheap mufflers, running straight pipe, etc. The only downside is you need a subscription to motortrend to watch them. Spoiler alert though... No back pressure is best, but it makes negligible power differences with all the combos unless you're well over 500 hp and chasing down minimal gains. I'd still like to get a better downpipe than the stock one but not expecting much of a difference perhaps a little more efficiency.

As for the waste gate preload, I think I'm going to try it to see what it does. Seems like the worst that can happen is that it runs out of air flow at higher rpm and I'd need to put it back to stock position.
Did you watch the one where they beat the headers with a hammer; no matter how badly they distorted the tubes there was practically no effect on h.p.
 

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Discussion Starter · #50 ·
Did you watch the one where they beat the headers with a hammer; no matter how badly they distorted the tubes there was practically no effect on h.p.
Just watched it... That's wild, would've never guessed smashing the headers up so bad would have essentially no change in performance.
 

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I know we got off topic a bit, but I watched a couple of episodes of engine masters that are eye openers with regards to 3" vs 2-1/2" exhaust, crunch bent vs mandrel bent, through muffler vs reverse flow and expensive vs cheap mufflers, running straight pipe, etc. The only downside is you need a subscription to motortrend to watch them. Spoiler alert though... No back pressure is best, but it makes negligible power differences with all the combos unless you're well over 500 hp and chasing down minimal gains. I'd still like to get a better downpipe than the stock one but not expecting much of a difference perhaps a little more efficiency.

As for the waste gate preload, I think I'm going to try it to see what it does. Seems like the worst that can happen is that it runs out of air flow at higher rpm and I'd need to put it back to stock position.
Those engines from Engine Masters are over 6 liters making 500 hp, three times the size of an ST engine. We easily make over 2 hp per cid, they can’, unless blowed can’t touch 2 hp per cid. One bank of a V8 of around 3 liter displacement are making 250 hp with a better valve train and individually balanced exhaust port. The amount of exhaust flow going thru our only miniature port is amazing, we have a very unbalanced exhaust flow between cylinders, that’s why the outer pistons are the first to go . It works ok at stock power levers, as soon you start messing up with the power ratio, you start getting increased knock counts on those cyl.
 
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After removing the stock turbo from my car, I adjusted the WGA to see the dynamics of the preload using a bicycle tire pump. The actuator rod has a range of motion, when you preload it shortened that range by the amount of the preload . Since the rod is attached to a level to rotate the wastegate cover/plug. If you tune for this event to counteract the ill effects, the turbo may live up to certain point depending how efficient is the tune. You are increasing the turbo bottleneck effect forcing it to over speed to counteract the increased back pressure. If the back pressure get to the point that the plasma like heated exhaust reenter the combustion chamber igniting the fuel before the spark causing detonation, It will be a sad situation. If you add preload you must tune for it.
I'm tuned for it
 

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After removing the stock turbo from my car, I adjusted the WGA to see the dynamics of the preload using a bicycle tire pump. The actuator rod has a range of motion, when you preload it shortened that range by the amount of the preload . Since the rod is attached to a level to rotate the wastegate cover/plug. If you tune for this event to counteract the ill effects, the turbo may live up to certain point depending how efficient is the tune. You are increasing the turbo bottleneck effect forcing it to over speed to counteract the increased back pressure. If the back pressure get to the point that the plasma like heated exhaust reenter the combustion chamber igniting the fuel before the spark causing detonation, It will be a sad situation. If you add preload you must tune for it.
It's actually supposed to be a fairly conservative reliable tune too I told him I wasn't concerned with squeezing every bit of power out of it.
 
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