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355 engine

Discussion in 'Technical Q&A' started by 355steve, Jan 26, 2004.

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  1. 355steve

    355steve Rookie

    Jan 22, 2004
    does anyone know up to wat bhp you can take the 355 engine upto before things start going wrong, what can these engines really handle??
  2. mk e

    mk e F1 World Champ

    Oct 31, 2003
    The twilight zone
    Full Name:
    The Butcher
    I'd guess the answer depends a lot on how your planning to make the hp. Any engine will stand 30% gain with boost (turbo/blower) or NOS. Using boost, a 308 will stand about 800 hp but need race gas, maybe 600 or so on pump gas. I guess a 355 engine will do at least that.
  3. midnite360

    midnite360 Rookie

    Dec 20, 2003
  4. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    To start, there is not much you can to with increasing the quality of the parts used inside the engine. Forged BIllet machined crankshaft, forged titanium connecting rods, forged aluminum pistons, nikisil coated iron bores, and titanium valves.

    The factory setup crosses the magic 4,000 ft/min piston speed at 8,000 RPMs where most productions engines would genade (the Vette LS1 passes this limit at 6,900 RPMs). The redline is set at 8,500 (4300 ft/min) and fuel cutoff occus around 9,200 (4650 ft/min). Yet the components in the Ferrari engine will, more than likely, be able to take close to the 5,000 ft/min piston speeds of racing engines--for a while. This corresponds to a potential rev range into the 9,750 RRPM band. {{Note, the F360 engine with its longer stroke lost 250 RPM redline compared to the F355. Ferrari understands that there is a limit to materials strength and that the feds require 100,000 miles (now 120,000 mile) emissions certification}}

    OK, lets say you want to take the F355 engine into this RPM band are willing to live with the <ahem> reliability of an engine operating at this speed. What other things are you going to have to do?

    Camshafts will need more duration and overlap from 16/56-52/16 to around 35/75-75/35, adding 40 degrees of duration and doubling overlap. Be real careful with the valve to piston clearance when specifying, grinding, and setting up this cam. No way to meet emissions of the feds, but might be able to pass a sniffer test. If sniffer tests are in the game plan, then you probably can't get away with more cam than 22/62-62/22 reliably (sic).

    Intake trumpets will need to be shortened 2", preferably by relocating the throttle bodies 1" lower into the intake manifolding and snipping 1" from the intake trumpets. Good luck on finding an inexpensive way to do this. This moves the intake resonance back up into the operating range of the higher PRM motor.

    Headers will need to be shortened 3" maybe 4" to retune these to the new RPM band. While you are in here, you should cut the front of the cat off, and add a 7" extension the size of the outside of the cat. This will serve as a collector and enhance the header wave pulses and work with the larger overlap of the Cam. If you build the motor and don't retune the intakes and exhaust headers, the engine will sign off just over 8,500 and you will not reach the potential.

    At this point, you might need injectors that can be controlled at the higher engine speeds, or increase the fuel pressure so the old injectors will provide the fuel the eingine needs.

    A minor cleanup of the intake ports (smoother walls) will enhance upper RPM power at the cost of lower RPM TQ.

    The exhaust valve in the Y-pipe needs to be reprogrammed so that it does not open until after the 4,000 RPM point due to the new cam and header tuning. And of course, the ECUs will need a complete reprogramming of the fuel delivery and ignition advance to deliver the goods.

    Low end power will be down 7% due to the longer duration cams, and the engine will not come alive untill the 4,000 RPM point (up from the 3,000 point).

    All in all, you should be able to get 60-75 HP with a life of 10,000 miles for the cost of <fumbling> a lot. It would probably cost more than a fresh crate F355 engine to build this beast due to every altered part being a one-off or custom fabricated.

    If you have access to 94 octane or better gas, you can add a little compression for another few HP and TQ.
  5. chaa

    chaa F1 Veteran

    Mar 21, 2003
    What is the difference engine wise between a road 355 engine and a challange engine? and Are they the same power? I am still learning about the car. Chaz
  6. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    The ECU is different, the exhaust valve is removed, and the mufler is different.

    The block, crank, pistons, valves, cams, belts, cylinders,.... are all the same (or were when it left the factory...) It might make some more power due to the removal of mufler and ECU, but we are talking handfulls of HP.

    There is more performance to be gained in a challenge car by weight removal than by engine tweeking.
  7. 355f

    355f Formula Junior

    Nov 1, 2003
    thanks for EXCELLENT informative posts.

    Lots of dyno work has been carried out by a company on my behalf and one realises the nonsense of chip upgrades on a NA car.
  8. bluekawala

    bluekawala Formula Junior

    Jan 22, 2004
    Ormond Beach, FL
    Yeah, that is really great info! So are the new ECU's you'd put in be aftermarket, from the factory customs, or is the stock peice re-programable?
  9. notoboy

    notoboy F1 Rookie

    Jul 8, 2003
    Full Name:
    Mitch, thanks for the post. I had wanted these questions answered for a while.
  10. Dale

    Dale F1 Veteran

    Oct 7, 2003
    Full Name:
    Dale Juan
    Tune the suspension that should give you 50 BHP.

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