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Difference between a 250 GTO engine and a 330 GTC engine

Discussion in 'Vintage (thru 365 GTC4)' started by 330GTCFERRARI, Oct 10, 2013.

  1. 330GTCFERRARI

    330GTCFERRARI Karting

    Jun 21, 2012
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    What are the key differences between these engines? Obvisouly, the GTO enigne is a bit more powerful and a racing engine, with more carbs. Why are they so much louder?

    How does the 275 GTB engine differ, besides the 2 or 4 cam?
     
  2. miurasv

    miurasv F1 Veteran

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    #2 miurasv, Oct 10, 2013
    Last edited: Oct 11, 2013
    The 250 GTO tipo 168/62 Comp. engine is 2953 cc and is in a higher state of tune than the tipo 209 3967 cc engine of the 330 GTC. They both make a claimed 300 BHP. The GTO engine has the 6 double choke carburettors (3 on 330 GTC), tipo 130 high lift camshafts, big valves with reinforced springs, higher compression pistons, Elektron magnesium for the cam and timing chain covers and is dry sumped. The GTO engine will be louder due to the exhaust and induction roar of 6 carbs and big valves?

    The 2 cam tipo 213 engine in the 275 GTB is of 3286 cc and came standard with 3 double choke Weber carburettors to make a claimed 276 - 280 BHP. 6 Webers could also be specified. The short nose 275 GTB Clienti Competizione also had 6 double choke Webers to make a claimed 300 BHP. The long nose 275 GTB/C tipo 213/Comp. (or tipo 213/66) engine had 3 double choke Webers, which were unique to this model, with rear facing velocity stacks, tipo 130 cams, Elektron magnesium cam and timing covers, a dry sump and made around 280 BHP? This engine was very similar to the 250 LM and used forged pistons and a special crankshaft.

    The tipo 226 275 GTB/4 engine, had 4 cams, 6 double choke Webers, a dry sump and made 300 BHP.
     
  3. 275GTBSaran

    275GTBSaran Formula Junior

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    #3 275GTBSaran, Oct 11, 2013
    Last edited: Oct 11, 2013
    Steve, one thing that comes to mind of the differences between 2 vs 4 cam. The 4 cam could rev to 8'ooo RPM, while the 2 cam 'only' untill 7'ooo. At the max point of 8'ooo the 4cam delivered a stated 300bhp - although it can be assumed that it might have been a little bit lower as all cars manufacturers overstated their BHP numbers.
     
  4. miurasv

    miurasv F1 Veteran

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    You are right. The 2 cam (SOHC) 275 with 3 carbs revved to 7600 and with 6 carbs to 7500.
     
  5. 275GTBSaran

    275GTBSaran Formula Junior

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    So the 6carb version did not rev as much as a 3carb version? Interesting. I assume you are also talking only about the 2 cam version above with 6carb as an option and not the 4cam 6carb engine?
     
  6. miurasv

    miurasv F1 Veteran

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    Yes, talking about the 2 cam version with 6 carb option. As you know, all 4 cams had 6 carbs.
     
  7. 275GTBSaran

    275GTBSaran Formula Junior

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    I once read somewhere that the among the 275 GTB versions, it is not at all clear that the 4cam engine was the most powerful in terms of pull. The 275 GTB has many setups as you know.

    2 cam 3carb
    2cam 3carb torque tube
    2cam 6carb torque tube
    2cam 6carb alloy body

    Apparantly I think the 2cam 3carb torque got the best reviews in terms of strength and pull of engine in one magazine, it even triumphed the 4 cam engine (which I would have thought with the increased BHP) would have always beaten a 2 cam car.
    It also could have been the 2 cam 6carb torque tube car though but I am sure it was NOT the alloy body 2 cam car (as the weight ofcourse would have explained in the increase in pull).

    I think the article was in one of the Cavallinos. Will try and find it.
     
  8. miurasv

    miurasv F1 Veteran

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    The torque tube refers to the drive shaft arrangement of the later long nose 2 cam (but not 275 GTB/C which used the "interim" shaft) and 275 GTB/4. This was a rigid tube that enclosed the drive shaft. Earliest 275s had an open shaft with a central bearing that could suffer from alignment problems. In between there was an "interim" drive shaft with constant velocity joints at each end which improved the original arrangement.

    The 2 cam 3 carb engine may have been more tractable?
     
  9. Daytonafan

    Daytonafan F1 Rookie

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    One of the key differences between any 3.0litre 250 and road 330 engine is the 330 block has wider bore spacings for improved cooling. The earlier 'Superamerica' 4.0 litre Colombo used in the racing 330LM and 330 LMB and 400SA doesn't have the wider spacings.
     
  10. DWR46

    DWR46 Formula 3
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    Some comments:

    Steve: GTO's use the SAME valve springs as a 250 GTE! Just another example of Ferrari using parts in the street engines that would stand up to the strain of racing. These springs are the weak link in the rpm capability of the GTO engine. At 9,400, they will break a valve spring. Don't ask me how I know this.

    275 GTB's have tachs redlined at 7,500 rpm and GTS's have tachs redlined at 7,000 rpm. The engines are identical. Two cam 275 engines generally power peak at 6,800-7,000 rpm on the dyno. Two cam 275's have a different camshaft profile than 250 or 330 street engines. In spec, it falls between the 250/330 cam and the GTO/LM/TR cam profile (sort of a 3/4 race design). If you want to read more about the various Ferrari camshafts, find a copy of my FML Tech Tips book from the 1980's.

    A good GTO motor will make 290-310 bhp on a dyno today. A 330 GTC engine will make 250-260 bhp on the dyno.

    A two cam, 3-carb 275 will dyno at about 235-250 bhp. A six carb unit at 265-270 bhp, and four cam engine at 250-265 bhp. All this on comparable dynos.

    All 275 two cam engines can run to 7,500 rpm regardless of how many carburetors.

    Six carb 275's power peak at about 7,200-7,400 rpm.

    GTO engines power peak at about 7,500-7,800 rpm and we normally shift them at 7,800.

    GTB/C engines are essentially a 250 LM engine with only three carbs (though they have large 32 mm choke tubes). they produce 280-285 bhp.

    Our LM motor made 330 bhp on the dyno with 10.0 compression. I was amazed it was this strong.

    Just some comments.
     
  11. miurasv

    miurasv F1 Veteran

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    #11 miurasv, Oct 11, 2013
    Last edited: Oct 11, 2013
    Thanks, Dyke. I was hoping that you would chime in. An absolutely superb article you did on the 275 GTB/C for Cavallino. Do you think that car was made even lighter than they would normally have done, making use of lots of magnesium parts, to compensate for the fact that it could only use the 3 carbs, not 6, and in so doing the car became dynamically superior in its handling as a result?
     
  12. DWR46

    DWR46 Formula 3
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    Steve: The GTB/C's were lightened using standard Ferrari practices of the era. The 3 carb situation was purely political, as far as I could ever tell. My research at the time pointed a simple clerical error that resulted in Ferrari failing to file a six carb option with the FIA for the car. Then it was too late so they made the best of it with the three special 40 DFI 3 carbs. When you drive these cars, you can tell they are seriously under-carbureted. The engines really need the six carbs to perform well.

    I am not sure about your comments related to the "handling". I think the "handling" was fine for a GT race car of this era. The significant item was the wire wheels which broke spokes regularly as a result of the new "M" Series Dunlop Racing tires finally generating sufficient grip to overpower the strength of a wire wheel.

    As I write this, you may be correct about superior handling as the three Speciale cars (6701, 6885 and 7185) while having lighter frames, use standard GTB suspension, handle amazingly and are LM fast.
     
  13. 275GTBSaran

    275GTBSaran Formula Junior

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    Interesting. So the best setup in terms of pull and power is the 6carb 2cam unit.
    I wonder why then that those are not as valuable as a 4cam car? Or even more valuable?
    I understand that technically the 4cam car is more advanced (independent rear suspension?) and perhaps more reliable. Still why has the market not caught on to this.

    Excellent Cavallino article on the 275 GTB/c. They are interesting cars and have potential in higher status in my opinion.
     
  14. miurasv

    miurasv F1 Veteran

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    #14 miurasv, Oct 11, 2013
    Last edited: Oct 11, 2013
    Dyke, I was just thinking that because of their oversight with the homologation papers and the fact that Ferrari knew the car would be under carbureted, they may have compensated with a superior, stiffer and lighter chassis of different tipo, 590A, thinner gauge alloy for the body, a dry sump for the engine and abundant use of magnesium? It was a more special, higher spec than the short nose 275 GTB Comp apart from the number of carbs.
     
  15. DWR46

    DWR46 Formula 3
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    Saran: The chassis of the 4 cam and 2 cam cars are essentially identical. Both have the same rear suspension. However, I seem to recall that the 4 cam, like the 330 GTC uses rubber bushes in the inner rear suspension pivots instead of the more accurate teflon coated metal bushings of the GTB/GTS cars. The rubber bushes give a smoother, quieter ride at a small expense in response.

    As to value of the 4 cam versus 2 cam cars, I can only speculate that the 4 cam is a more sophisticated, comfortable (see above) car. It has more parts!! I believe that the 4 cam was developed as a response to Lamborghini and Maserati both having DOHC engines to sell to the customers and Ferrari had none.

    Interestingly, most 4 cams have only 29 mm chokes in the carbs instead of the 32 mm chokes in the six carb 2 cam. This is a major reason that 4 cams do not make the power that six carb 2 cams do. I have always thought that the smaller chokes were the factory's way to try to get some low end torque back into the 4 cam motor to make it more driveable. They succeded, as 4 cams are very smooth to drive, but the factory sacrificed some top end power for the smoothness. Some 4 cams have the 32 mm chokes and are quite a bit quicker.
     
  16. miurasv

    miurasv F1 Veteran

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    #16 miurasv, Oct 12, 2013
    Last edited: Oct 12, 2013
    Very interesting is that in Keith Bluemel's Cavallino article (Thanks, Edmond) where he is fortunate to compare short nose 275 GTB Competizione 7407 and long nose 275 GTB/C 9041, he states that the dynamometer BHP figures for the short nose care were 290BHP @ 7300 rpm and 288 BHP @ 7000 rpm for the long nose car, both from rebuilt engines. So the 3 carb 275 GTB/C was only 2 BHP down on the 6 carb 275 GTB Comp.

    Also, both cars were weighed with 10 imperial gallons of fuel (45 KG) and the short nose 275 GTB was found to weigh 1220KG and the long nose 275 GTB/C 90 KG lighter at 1130 KG which is very significant.
     
  17. DWR46

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    Steve: Remember that dyno results can be "altered" by just changing the Correction Factor to give any output numbers you want. I have seen massive power outputs claimed for Ferrari engines from some "reputable" engine builders. However, when you examine the actual dyno reports, you find they used barometric pressures so low, that the dyno had to have been in the "eye of a hurricane" at the time of the run. We use a Superflow computerized unit that we set up very conservatively. Actual total power output is not as important as the gains you can make over the intial baseline by changing cam and ignition timing and carb jetting. As to the reported dyno results in the magazine article, if they were done on different dynos, by different operators on different days, I would not expect them to be comparible. Remember, magazines are in the business to sell magazines, not necessarily educate readers. Over the years, I have been consistently disappointed by the level of automotive knowledge exhibited by most "well known" journalists. Don't believe everything you read in the car magazines.

    As to the specific engines, the 6 carb motor may well have had Tipo 130 cams installed and had the compression raised. Then it could have produced the claimed 290 bhp. The ten 1965 Competition GTB's produced used STANDARD 6 carb engines, no hot cams, high compression pistons, special cranks or rods, just the same motor as found in any 6 carb GTB.
     
  18. miurasv

    miurasv F1 Veteran

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    #18 miurasv, Oct 12, 2013
    Last edited: Oct 12, 2013
    ^^^Thank you, Dyke. I understood from the article that the figures were taken from both cars at the same time, but I take on board fully what you say. If indeed the figures were taken by the cars when together, then I find the weight figure to be the more interesting and significant as a 90KG saving from a 1220KG car would be noticeable and the actual BHP figures are not that important, but the fact that they were comparable is. Also, as you have said, the motor in the short nose car is basically a standard 6 carb unit, although still superb of course, whereas the motor in the long nose car is very special indeed, to LM spec, albeit with 3 carbs. Anyone who had read your Cavallino article on the 275 GTB/C may just appreciate how very special this car is.
     
  19. 300GW/RO

    300GW/RO Formula Junior

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    Great information, thanks. Lots of bits to recall, yet am I on solid ground with this:
    "motor in the long nose to LM spec, albeit with 3 carbs" therefore long nose six carb set-up NOT factory? thanks,

    Jack
     
  20. miurasv

    miurasv F1 Veteran

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    #20 miurasv, Oct 12, 2013
    Last edited: Oct 12, 2013
    The long nose 275 GTB/C competition car, of which 12 were made, had 3 carbs of a type that were unique to that model. Standard long nose 275 GTBs were made with 3 carbs, but 6 carbs was an option, and came in both alloy and steel bodies.
     
  21. amc

    amc Karting

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    Can somebody tell me the length and width of a 250 engine cam cover, please?
    I'm drawing a SWB engine in 3D...
     
  22. swift53

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    23 - 9/16" x 7 - 5\16"

    Regards, Alberto
     

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