Speculating beyond bolt-ons.

Discussion in 'Fiesta ST Engine Upgrades' started by wash, Oct 17, 2013.

  1. limbo

    limbo Active Member

    Why is your main goal tire spin? If you're spinning tires in higher gears you have way more power than you need and that's just going to create a tedious auto-x experience. I'd rather be able to point the car, mat the throttle and go rather than fussing around with modulating throttle to keep the car from pushing everywhere.

    I think you need to pick your focus. Setting up this car as BOTH an auto-x and drag car with lofty expectations for both is going to be frustrating.
    Smokin, RodMoe and fifoci like this.
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  3. wash

    wash Active Member

    My main goal is not tire spin, its not bogging when I hit the gas from a slow roll in first.

    Enough power to spin the wheels is enough that it won't bog.

    I don't recall the quote but I think either a Porsche 917 driver or a Can Am driver said I'll have enough power when I can spin the wheels all the way to the end of the straight on the longest track we race.

    I'm not going for that but he was right about how much is enough. Its always better to have and not need than need and not have.
  4. fifoci

    fifoci New Member

    Idk of any car that bogs in first...
  5. peoples1234

    peoples1234 Member

    I agree, I don't think my FiST bogs in any gear unless I am not paying attention and stay in 6th when I should be in 2nd. It definitely doesn't bog in 1st.
  6. fifoci

    fifoci New Member

    That 'bog' you feel is probably the throttle delay I was talking about In another thread.
  7. Just remember if you do most of the mods you wrote about, this will be a totally different car. I think the popularity of the Fiesta ST is the balance. That balance goes away quickly once you're introducing big mods/power. I think 50-75 hp increase at most would be great with bolt ons. After that (or even before), you need to upgrade the brakes, suspension, clutch and deal with the massive torque steer that's bound to come. Which will suck btw. Also, this is a 1.6cyl. It's never going to have V8 torque down low.

    Absolutely good luck with your project and I'd love to hear the numbers you end up with. I assume most Focus ST parts will be an upgrade for this car. Tons of info out there now about the route those guys have gone. Be careful what you wish for though........a massively modded Fiesta ST may not be as fun as you think. On the street or at the track. 1/4 mile probably if you can make it hook and not bog with slicks.
    Last edited: Nov 21, 2013
  8. fifoci

    fifoci New Member

    I don't see tq steer being an issue. And if so, LSD is usuall the fix.
  9. Torque steer is an issue on a stock Focus ST and Mazdaspeed3. How could it not be an issue on a highly modded Fiesta ST?
  10. fifoci

    fifoci New Member

    It's a totally different chassis.
    My focus had 400hp. Not a single ounce of tq steer.
  11. wash

    wash Active Member

    There are really no parts from the Focus ST that translate to the Fiesta ST except maybe the limited slip diff might be compatible.

    The Focus RS Revo-knuckles I mentioned would be essentially a complete redesign of the front suspension and possibly steering, an extreme solution if I wind up with a really bad torque steer problem.

    I don't think it will be bad, something like a Cobb stage 3 Focus ST has lots more torque than I can hope for and I haven't heard people saying the torque steer is unbearable. The Fiesta ST is just a slightly smaller and lighter car, there is no reason to expect big problems from around 300 HP.

    If I'm going to upgrade the turbo, the EFR I'm looking at is the option that should spool as quick as anything bigger than a KP39 and once you get to the point of a new turbo, new plumbing, ECU tuning devices and software, it does not make sense to leave power on the table if all you have to do is write a decent tune to get it. Its not a matter of building for 300 HP, its a matter of building for that turbo and 300+ HP is the potential if you build it right. If there was another turbo out there that would spool quicker and still give me more high rpm boost than stock, I would be trying to figure out its match but there isn't anything like that out there.

    I'm going to try to do better than a decent tune because I know some people who can help me squeeze out more. A race tune with ALS might be possible so I'm going to see what can be done. I would probably use ALS with a two-step rev limiter and neither would be used often, just a tool for certain race situations when points are on the line.

    What makes a turbo spool quickly:

    #1, low inertia in the turbine and compressor wheel.

    #2, low friction in the bearing system.

    #3, a twin scroll housing to better scavenge the exhaust pulse energy at low rpm.

    The turbo I'm looking at is the smallest EFR turbo and has a Titanium Aluminide turbine wheel which has about 1/2 the density of a Nickel super alloy wheel (like Inconel) so the inertia is low. The bearing assembly uses large ceramic ball bearings rather than plain bearings, this reduces friction and increases the maximum bearing thrust load which improves the durability. It also has a twin scroll housing so all the boxes are checked.

    If you want more power than bolt-ons can provide, its going to be this path or very similar. Its a shame but the KP39 is just tiny so the normal bolt-on stuff will only give small power increases.

    I'm not worried about changing the balance of the car and I'm not going for a drag race setup, if anything I'm going for a time attack/street setup.
  12. fifoci

    fifoci New Member

    I just planned to do intake exhaust hard piping and intercooler then possibly an external. This is going to be my daily beater that gets me 130 miles of commuting per day.
    At the end of the day it's a fiesta, economy car...
  13. moshaholic2

    moshaholic2 Active Member

    So pumaspeed reported yesterday via facebook that they are at 230bhp w/ current turbo and speculate that they *might* be able to get 240-45 max from it.
    Not bad in this little car. But that turbo is likely putting in major work at those #'s.
    Last edited: Nov 26, 2013
  14. fifoci

    fifoci New Member

    Do we know what they have done to the car?
  15. RodMoe

    RodMoe Well-Known Member

    Yes moshaholic2 is correct I got this from their post and later comments. They gave no Torque numbers but said the rods and pistons good to about 270 hp

  16. wash

    wash Active Member

    Exhaust manifold design thoughts:

    Headers are usually designed to tune for exhaust scavenging at one specific rpm, longer and smaller tubes shift the tuning point to lower rpm but at some point small becomes a restriction at higher rpm.

    In a Fiesta, small tubes are easy but long won't work. Throw in a turbo and a lot of the traditional rules go out the window.

    First thing, a twin scroll turbine housing dictates a sort of 4-2-1 header (tri-Y). Cylinders 1,4 and 2,3 are paired with the tubes merging close to the turbo flange and the twin scroll housing itself kind of acts like the third "Y".

    Its hard to find the speed of sound in exhaust gas at high pressure but it's got to be greater than low pressure which would suggest that longer pipes are needed to tune a turbo with significant back pressure but STs don't have a lot of space so if I can get close to 16" I'll be happy (I bet 32" would be closer to tuned).

    There is a lot of discussion comparing equal length headers with cast manifolds and fabricated log style manifolds. Race cars seem to have nice equal length setups if they will fit but people who have tried both say the differences are small.

    Burns Stainless has some things to say that make a lot of sense, they like equal length, smooth bends and slip joints to relieve stress. I think I can agree with all of that and will try to build that as much as possible.

    When the topic comes to length, diameter and pulse tuning, things get fuzzy. A twin scroll turbine uses pulse energy to spool up quickly so that's a topic I'm interested in.

    Two things that seem to work together are that pulse energy relies on the velocity of the gas and as a gas is allowed to expand it slows but the turbine back pressure at high rpm is probably greater than that of a slightly small primary tube so I want to match the size of the exhaust port and carry that almost all the way out to the turbo flange. I want the transition from exhaust port size to turbo flange size to be smooth so that my low volume header will maintain as much velocity and pulse energy as possible.

    Even if the primary pipes are kept small there is no way to make them long enough to tune for mid-range but trying to go short does not seem to hold any advantage. Equal lengths would help but I will be satisfied if I can keep the paired primaries equal.

    Of course the biggest priority is making it fit but now I have a good idea of how I want to make them.
  17. moshaholic2

    moshaholic2 Active Member

  18. Sekred

    Sekred Active Member

    Just to throw something more into the equation and what most people don't relies and may have trouble understanding is that rotational speed of the turbocharger is factored primary by exhaust gas heat and not exhaust gas pressure. As the exhaust gas exits the volute ( snail) it expands acting on the turbine vanes and drives the turbine wheel. The extent of gas expansion in the turbine housing is determined by the amount of exhaust gas heat and size of the volute.
    Be aware that with any tube type manifold verse cast iron design, you are going to lose heat. I would not bother with tune length, it not worth the effort and its not going to work on a road car with a 6500 rev limited. The longer the exhaust manifold the more heat your going to loose and the more thermal expansion and contraction that will occur, increasing the chances of cracking and bolt breakage.
    The fact that your going to a run another turbo means you have no choice but to build a manifold and the fact that it will have to be a twin scroll complicates things further. Be under on illusions, getting this right won't be a easy task and getting it right first go, unlikely.
    Good luck with it and don't obese with having to have the latest and greatest thing on the market.
  19. wash

    wash Active Member

    Yeah, I've read a lot of opinions about heat and there are header wraps and turbo blankets if I find heat loss is a problem.

    At low rpm everything is going to be cool and trying to suck heat out of the exhaust gas but heat transfer happens over time so keeping the pulse fast and not allowing the gas to expand before the turbine will hopefully get the exhaust through the turbo before it has a chance to cool much.

    I've seen that Pumaspeed header. I sent them an email asking to buy a header flange, haven't heard back.

    The main problem is that it still uses a KP39 turbo.

    What I have to build is going to have longer pipes because the paired tubes have to be on the sides rather than front and back of the turbo flange.

    Here is a picture of what Burns Stainless thinks is a near ideal turbo header (for a sand rail):


    It looks like a 4 in to 2 in to twin scroll turbo flange with pretty long primary tubes. I see there is a 2-1 merge before a section of straight tube that heads to the turbo flange, I'll have to ask about that straight section.

    Any way, that header does not look like it was designed to retain heat. Mine will certainly be shorter with smaller diameter primaries, ideally something half way between the Pumaspeed and the Burns
  20. Sekred

    Sekred Active Member

  21. wash

    wash Active Member

    I've looked at a lot of full race stuff after seeing their Fusion and talking to their guy at SEMA.

    That layout looks like its probably too big for a Fiesta, probably for a longitudinal engine Sylvia or something.

    One thing you will notice is two wastegate tubes, one for each scroll. The EFR has an integrated wastegate so that's two wastegates you don't have to buy and a bunch of plumbing you can avoid. The price looks a lot better when you factor that in.

    Full race has good stuff and probably will make what I want to build eventually but I'm not going to wait.

    I should place an order with Burns soon but I'm not sure they make 321 bends small enough to match the exhaust port.

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