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Supercharging a 355

Discussion in '348/355' started by Subarubrat, Apr 1, 2009.

  1. Subarubrat

    Subarubrat Formula 3

    Apr 1, 2009
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    On many forums a post like this, and certainly as a first post, can be like slapping on a kick me sign, I will just have to take my chances. After allot of thinking I am going to sell my Lotus and buy a 355. They are very different cars and it was a difficult decision to make. The one shortcoming in the change is the raw power that I am used to from my Lotus (supercharged and upgraded) and my STi (upgraded, around 4 seconds 0-60) just isn't quite there in the 355, close but not there. That coupled with my character trait of leaving nothing stock means something has to happen.

    After doing allot of looking at the diagrams and a real car I am certain that a supercharger is very doable. There are many things about it that do not worry me and a few things that do. And it is certainly possible that I am unaware of something in either column and would love to hear from others. And that is really what I am asking here, what have others experienced? I am not an 18 year old Civic driver bench racing. I am an aerospace engineer and I build aircraft (real ones) as a hobby, so fabrication of brackets, fittings, tubing, sheet metal, composites, welding etc. are skills that I am comfortable with. I have done several SC and turbo installs in a variety of cars over the years as well as other mods and fabrication. Getting the SC in the car and all piped up is the easy part, making it run right is the devil in the details. I don't think that this project has to be all that difficult or even expensive compared to something like a Mustang. I am not looking to achieve an unreasonable output, probably about a 30% increase in WHP using moderate boost around 7~9Lbs which is commonly done in cars with similar compression ratios.

    My concept for the physical install is to use a vortech low profile SC that is often used in 3~6ltr engines on cars where space is a factor. The airboxes will be removed and a common filterbox on one side of the car will feed through a tube running parallel to the engine up to the SC's intake. The output tube will run to the rear on the opposite side of the engine and feed into an air to water intercooler located where the other airbox originally was. And from the IC to the intake tube. The air to water IC will allow me locate the relatively small radiator without having to worry about the problems of an air to air IC.

    As far as engine management I am thinking of going with a Motec ECU and uprated fuel pump + injectors. I have used motec in the past on an Impreza and the whole process of setting up the injectors, sensors, boost control etc. was pretty painless. Loading a sloppy rich and retarded ignition map and tuning from there took about an afternoon, after that I drove it up to a tuner with a dyno and all the gear to dial it in. The end result was a very drivable car that ran great.

    In all this, nothing has leaped out at me as being a major problem. Any thoughts?
     
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  3. junglistluder

    junglistluder F1 Rookie
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    where in VA are you located? I too went from a Lotus (sc'ed and upgraded) to an F355. Totally different cars.
     
  4. Subarubrat

    Subarubrat Formula 3

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    Yes they are, and if I could keep both I would in a heartbeat. As you know that Lotus comes alive once you SC it. I live about halfway between Warrenton and Culpeper
     
  5. UConn Husky

    UConn Husky F1 Rookie

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    let's hear it for the Subies!!!

    There's a big reason not to start modding the 355 as you discuss - engine cost. If you blow the STi you can get a whole new motor for peanuts (relatively speaking). If you blow a 355 motor, depending on exactly how much damage there is, you could be in the $25-$30k range I've heard.

    Specifically, there's the matter of compression ratio. The STi is around 8.5:1 I believe, giving lots of room for boost without detonating (i'm at 21 psi now). The 355 is more like 11:1...squeeze in much more air and you can have broken pistons knocking at your door. It's not impossible, there are a few twin turbo 355's running around making lots of torque and power...but it's still a risk. I personally love to tinker and upgrade, but I can't stomach the risk of blowing the 355 motor to gain a few tenths in a 0-60 or to shave a half second on a track.
     
  6. junglistluder

    junglistluder F1 Rookie
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    our supercharged lotus cars ran 11.5:1 compression ratio. boost was limited to 10 psi max on stock ratio. I ran 8psi with no problems whatsoever.
     
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  8. UConn Husky

    UConn Husky F1 Rookie

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    nice...ok maybe I'm being overly cautious. It does still depend on how close to the edge the pistons were designed. For example I know some valve springs can be over-revved by 1k rpm all day and be fine, others are on the ragged edge at OEM redline. I guess the best comments on engine life would be from the guys already running turbo 355's...Maybe try searching in the challenge or technical forum.
     
  9. Subarubrat

    Subarubrat Formula 3

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    #7 Subarubrat, Apr 1, 2009
    Last edited: Apr 1, 2009
    "The STi is around 8.5:1 I believe, giving lots of room for boost without detonating (i'm at 21 psi now). The 355 is more like 11:1...squeeze in much more air and you can have broken pistons knocking at your door."

    Very true, valid points. With the STi I am pulling over 1.5 bar and have a mid range output as modded STi's go, around 450Hp, I am far from the top of the pack. I have 120k miles and drive it hard. On the Lotus with 11.5:1 we are running lower boost, often without intercooling too with excellent results just as junglistluder said. You are naturally limited to lower boost, boost raises the effective CR and starting with a higher CR means less boost. It also means better performance at lower RPMs. In the end a low CR boost specific engine has more potential for peak HP. The point being that you get greedy and run higher boost and your asking for the risk and problems that were mentioned. 7~9Lbs with intercooling and good management is an elevated risk over stock, but a pretty conservative one.


    "For example I know some valve springs can be over-revved by 1k rpm all day and be fine, others are on the ragged edge at OEM redline."

    Case in point, Subaru EA82 naturally aspirated engines, throw so much as a pound of boost and the pistons disolve, well not that bad, but they are delicate.
     
  10. Mr Dobermann

    Mr Dobermann Karting

    Jul 31, 2005
    162
    Nice thinking...

    Have you thought of where to place the Supercharger, and where to install a pulley for the Supercharger belt on the 355 engine? This can be a little tricky, unless you decide to remove the AC-pump... Thats the only place i can think of, if youre gonna do a set up with a Centrifugal SC.

    Why dont run twin Turbos instead? But, turbos need a better mapping with a aftermarket enginemanagement. As you probably know already... Doing twin turbos is in my opinion much easier, because you can use the OEM(or aftermarket) headers and adapt the turbos to these in a good way. But the boost with a centrifugal SC is nice, it just increases with the engine rpm, and this is also the thing with the 355 - the high revving engine.

    With this high compression ratio in the 355 engine, i personally would recommend lowering it before boosting. The risk for self-detonation is gonna be way too high without lowering the comp-ratio, in my opinion. Get some good forged pistons and start around 9,0-9,5 comp-ratio. The factory titanium conrods on in the 355 engine will last.

    And If you are gonna do this, do it the good way from the beginning, but it WILL definetely cost you a lot, both money and time.

    How will a aftermarket enginemanagement play together with the 355:s electrical system for the immobilizer for an example?

    Kimmo/Sweden.
     
  11. hacker-pschorr

    hacker-pschorr Formula Junior
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    #9 hacker-pschorr, Apr 1, 2009
    Last edited: Apr 1, 2009
    Motec is a great system, If I were you I would look into Autronic. One of our prototype supercharged 928's is running Autronic, it's an excellent system. Five liter low compression 32V V8 with 30+psi of supercharged boost. The engine is 100% stock except for using pistons from a 944 Turbo. This car has multiple timing and fuel maps for each cylinder due to the unequal length runners in the stock intake manifold.
    Or "normal" systems use the stock ECU that is fully tunable so no need for a stand alone with our standard kits that max out around 12pis on a stock 928. IMO it would be great to retain the stock ECU on the Ferrari, if it was tunable, to retain the OEM knock sensors.

    Ray Hall who was with Autronic for a number of years is now working on a different system that is supposed to be very similar to Autronic with more features.

    http://www.vi-pec.com/
     
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  13. Mr Dobermann

    Mr Dobermann Karting

    Jul 31, 2005
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    But the stock 2,7 motronic is tunable, right?

    Kimmo/Sweden.
     
  14. Mr Dobermann

    Mr Dobermann Karting

    Jul 31, 2005
    162
    By the way - Anyone who have removed the plenums/airboxes on a 355, and remapped the ecu:s without the airflowmeters, just with open runners and the TPS?

    This must be doable and i can imagine the sound of the engine in hysteric scream at 8500 rpm...

    Anyone?

    K.
     
  15. Subarubrat

    Subarubrat Formula 3

    Apr 1, 2009
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    "Why dont run twin Turbos instead? But, turbos need a better mapping with a aftermarket enginemanagement. As you probably know already... Doing twin turbos is in my opinion much easier, because you can use the OEM(or aftermarket) headers and adapt the turbos to these in a good way. But the boost with a centrifugal SC is nice, it just increases with the engine rpm, and this is also the thing with the 355 - the high revving engine."

    I have both an super and turbo charged car, and have dealt with both over the years and each has it's ups and downs as well all know. In this case I am thinking SC for a few reasons.

    First, since the engine is not originally turbo the coolant and oil paths are not there, and since it lacks a oil sump the oil return gets just a bit more complicated, not horrible. With an SC there are no coolant or oil paths to deal with and plumbing is much easier. Exhaust plumbing is untouched too.

    Second, One SC and one IC means simplicity and lower cost over the turbos.

    Third, Tuning for a SC is simpler with fewer excursions from the norm. Turbos aren't as linear

    Fourth, Based on my experience with my Lotus, a high revving 8,500rpm engine with a 11.5:1 CR with a reprogrammed stock ECU that was never intended for boost, non intercooled, yielding great performance with no bad habits. The factory SC lotus elise does the same thing as the aftermarket kits and yields about the same performance. I have seem similar results from other high compression engines. Given what is at stake I like the margin of the IC and better engine management.

    Fifth, While a modern turbo engine has very little lag compared to the old days (my STi with the FP green has very very little) the SC is still a bit more responsive and in a car like this, and the Lotus response is nice.



    "With this high compression ratio in the 355 engine, i personally would recommend lowering it before boosting. The risk for self-detonation is gonna be way too high without lowering the comp-ratio, in my opinion. Get some good forged pistons and start around 9,0-9,5 comp-ratio. The factory titanium conrods on in the 355 engine will last."


    I think that the preponderance of boosted engines in the same compression ratios in cars like Lotus, Subaru's EJ25 and a the Toyotas, Hondas etc. some even as factory kits, shows it can be done if you manage right and don't get greedy. If I wanted more than 30% say 50% or so then a lower CR would be mandatory. When people were developing SC kits for the Elise the same points were made, and there are allot of people driving around with fantastic results now.
     
  16. mk e

    mk e F1 World Champ

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    I've done a few 308 SC systems with excellent results before deciding to just pull the V8 and build a V12 for it.....which maybe wasn't my best decision:
    http://www.ferrarichat.com/forum/showthread.php?t=170171

    I much prefer screw type superchargers myself on street cars because you have boost right from idle but anything is better than nothing.


    There is a TT355 in OZ, if you do a search you should turn it up. It's an all stock engine and 9psi or so of boost and holding up quite well the last I heard. Good luck!
     
  17. vvassallo

    vvassallo F1 Veteran

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    I could see supercharging a 348, but a 355 is another matter. This is a far more complex and stressed engine that has more restrictive smogging. Plus those weak-azz headers are already at the fringe in terms of heat management. Blasting more plasma through them is certainly going to pizz them off fer sure. Not sure about the effect on those potentially problematic valve guides too.

    There's far more space in a 348 to do this, a stronger engine that's less stressed that also runs at about 1000 rpm less. Of course, I also have a difficult time seeing where you are going to mount the pulley for the SC as there is infinitismally small space between the engine front and firewall of either a 355 or 348. I can't see running your SC at the 8000-8500 rpm redline in a 355. All addressable I'm sure, but I think the older car is a better donor vehicle, IMO.

    FWIW, I' m pretty sure you can get more power out of the 355 normally aspirated, not another 100 Hp mind you, but more, say over 400, just cleaning up the intake and exhaust flow. How much do you need? Where you going in that car you need to have a 3 second Ferrari?
     
  18. Subarubrat

    Subarubrat Formula 3

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    The header weakness was the first issue I read about next to "Drum roll please................Timing belts"

    As for the valve guides, I have read a wide variety. Some saying the early cars had bronze ones and further that the later ones were fine. I need to look into that more by all means.

    As far as the belt, a sub 12 psi SC doesn't need a dramatic cogged belt. My lotus has a 3 rib belt under light tension. I think the accessory belt would be fine.


    "How much do you need? Where you going in that car you need to have a 3 second Ferrari? "

    I can't claim any high minded motives here. I carry a .32 cal pistol for concealed carry, yet I own a .50 cal Desert Eagle and love large guns, yet I see the practicality for purpose. I can be reasonable. Yet I also love, more. And more isn't always bad. I hear a thousand and one lotus forum members say things about the Lotus similar to that about modding a 355. Yet I can say that the Elise is worlds apart better at 280hp Vs 190Hp. It had 11.5:1 and it didn't blow up. I am not looking for a 3 second 355. Any more than I would claim that a 355 or 360 is a superior to the Z06 Vette. If that Vette had a prancing pony it would sell for at least 2x as much. I don't want to make a 3 second 355/360. I just believe that forced induction is the replacement for displacement. With modest boost the 355 is capable of being much more the way I see it.
     
  19. UConn Husky

    UConn Husky F1 Rookie

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    There's nothing like OEM forced induction cars....Ferrari got it right in the F40, but then sadly stuck with NA...
     
  20. Mr Dobermann

    Mr Dobermann Karting

    Jul 31, 2005
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    The only place i can see to install a centrifugal supercharger on a 355 is where the AC-pump is located. And this is indeed the only place. You will definetely have to use the accessory belt for this, since there is NO space at all to place a new pulley in front of engine for it(5-10 mm clearance to the firewall). Then you need to route down the air inlet to the SC, under the left exhaust manifold. Next thing is to mount proper piping for the ass-whipped-air-out from the SC. Also somewhere around the left header. You will get long piping, however you like it or not. And you will have to live with a non-Airconditioned cabin...

    If you get a 355 you will see what im talking about.

    Are you gonna run a SC with internal oil lubrication? No feed and return? Why?

    A electrical pump is a good solution to evacuate the oil from the SC to the higher mounted Oil sump.

    But - its doable. Definetely. It has also been in my mind, but i really dont wanna destroy the characteristics of the 355. As Wassallo says, i would also go the N A way, there must be other cams to put in these(Havent seen any yet though), maybe port the heads, slightly increase the Comp ratio, better Headers, airboxes and so on. Or maybe map the engine with no airboxes at all, just with straight runners...

    Just my thoughts.

    Kimmo/Sweden.
     
  21. mk e

    mk e F1 World Champ

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    The belt size will be a function are pressure and total air flow, so a bigger engine will want a bigger belt than a small engine at the same boost. On my car a 6 rib worked ok at 10 psi and 360 hp, but a 10 rib was required at 22 psi and 540 hp. 9 psi in tha 355 should put you in the 500+ hp range so I would expct you would be looking at at least 6 ribs and more likely 8-10. You can still use the accessory belt, but you'd need to replcae all the pulley to match the belt you choose.
     
  22. mk e

    mk e F1 World Champ

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    You can run shaft back and mount the SC on the side or back by the bell housing...maybe? I've seen that done on several installs where space was a real problem.

    On th 308QV I put it right on top of engine blowing up into a custom intake that held a water/air intercooler and kept the factory length runners. It was a pian to build but once finished it worked quiter well.
     

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