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  • 94 Mercedes motor

    I've read Beast, but now I'm drawing a blank on something related to the rules. Was there anywhere within USAC's rules that required the block to be "stock" or "production" based, or was it simply a matter of limiting cubic inches and boost based upon pushrod vs overhead cam? Any exact info would be greatly appreciated.

    And also, just to clarify, I'm not asking what the "intent" of the rules were or who it was supposedly written to help - but more of what they exactly allowed (or didn't allow)

  • #2
    Originally posted by carl_fisher_78 View Post
    I've read Beast, but now I'm drawing a blank on something related to the rules. Was there anywhere within USAC's rules that required the block to be "stock" or "production" based, or was it simply a matter of limiting cubic inches and boost based upon pushrod vs overhead cam? Any exact info would be greatly appreciated.

    And also, just to clarify, I'm not asking what the "intent" of the rules were or who it was supposedly written to help - but more of what they exactly allowed (or didn't allow)
    Had nothing to do with stock block or production-based. It was just pushrod vs. chain- or belt-driven cams (overhead cams).

    The intent was for that to be an enforceable distinction between Stock Block and Racing engines. There were very few Production Car V8 engines at the time with Overhead Cams. The chief exception would likely have been the Porsche 928 engine.

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    • #3
      My understanding, based on nothing technical, was that there were rules written for stock block engines like the Buick. Because the Buicks continued to be consistently unreliable and folks like Pontiac and Foyt were giving up, USAC deleted the part about the block being production-based so that someone like Buick could come up with a block similar to the production design but beefed up for racing. And thus the opportunity for an engine like Ilmor's was created.

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      • #4
        The Mercedes 500I is probably best described as a purpose-built pushrod engine. The rules that were drafted for those types of engines (another one being the Greenfield), did not require a 'stock block', or [any] production-based parts.

        The V-6 Buick/Menard was a stock block, under "stock block" rules. But IIRC, over the years the requirements for production-based parts was more and more relaxed.
        Doctorindy.com

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        • #5
          Originally posted by carl_fisher_78 View Post
          I've read Beast, but now I'm drawing a blank on something related to the rules. Was there anywhere within USAC's rules that required the block to be "stock" or "production" based, or was it simply a matter of limiting cubic inches and boost based upon pushrod vs overhead cam? Any exact info would be greatly appreciated.

          And also, just to clarify, I'm not asking what the "intent" of the rules were or who it was supposedly written to help - but more of what they exactly allowed (or didn't allow)
          My memory of this era is as follows. The Buick engine in the 80s and a few other pushrod engines were stock block-based and were allowed to have additional inches of turbocharger boost. Sometime around 1992, the rule was expanded to give the same advantage to purpose-built pushrod racing engines - which prompted the creation of the Penske Ilmor/Mercedes engine. At the time, both purpose-built and stock-block pushrod engines were allowed 55 inches of boost versus 45 inches for other IndyCar engines. After the 1994 500, the rule was changed again (twice) cutting the boost on purpose-built pushrod engines with the second cut making the Mercedes and similar purpose-built pushrod engines as uncompetitive. However, the Menard engine program, which was a stock-block-based pushrod engine, was not affected by this change and the boost level remained at 55 inches. They ran the engine in 1995 and 1996 before the new IRL engine specs.

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          • #6
            Originally posted by Bullwinkle View Post

            Had nothing to do with stock block or production-based. It was just pushrod vs. chain- or belt-driven cams (overhead cams).
            That is incorrect.

            There were rules in place which dictated that in order to be of higher displacement and use higher boost than the purpose-built, 2.65 liter DOHC engines, the 209 cubic inch motors (such as the venerable Buick V6) had to use stock blocks and use pushrods with the single cam located in the original, factory location.

            Then, in the early nineties, USAC dropped the stock block requirement for the pushrod 209 motors. USAC's thinking was this would serve to help out the "little guys" such as Peter Greenfield and Lee Brayton. Both developed purpose-built 209 V8 pushrod motors. USAC figured that the big race engine suppliers (Cosworth, Ilmor, etc.) would continue to rely upon their proven 2.65 liter DOHC engines rather than go to the trouble and expense of designing and developing pushrod motors just for Indy. USAC, clearly, was wrong.

            Penske and Ilmor saw the advantage available under the rules and you know what happened thereafter.

            The Greenfield engine never performed well enough to make the race.

            John Menard, upon seeing Brayton's engine perform well on the dyno bought the entire program and invested heavily in its continued development and production, but didn't manage to have it ready in time for the 1994 race. He had every intention of running it in 1995 (and eventually selling engines to other teams), but, as mentioned above, USAC and the Speedway changed the allowable boost for the purpose-built pushrod engines which ultimately rendered them uncompetitive. Menard was left with a small mountain of blocks and parts, lots of sunk money, and nothing to show for it.

            It is said that Cosworth was in the process of drawing up their own 209 pushrod V8, but it never got beyond the drawing board.
            Last edited by Spike; 11-07-2019, 05:46 PM.
            "I would really like to go to NASCAR. I really enjoy NASCAR and if I could be there in a couple of years that's where I'd want to be." - Jeff Gordon (after testing a Formula Super Vee)

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            • #7
              Originally posted by Bullwinkle View Post
              . There were very few Production Car V8 engines at the time with Overhead Cams. The chief exception would likely have been the Porsche 928 engine.
              What? Everybody Except the Ameican big three and Toyota had OHC V8 engines. GM and Toyota had both OHC and OHV.

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              • #8
                Originally posted by RS2 View Post

                What? Everybody Except the Ameican big three and Toyota had OHC V8 engines. GM and Toyota had both OHC and OHV.
                Chevrolet had the DOHC LT5 V8 in the Corvette ZR1.
                "Only a fool fights in a burning house."-Kang

                "If you listen to fools....The Maaahhhhb Ruuuules....."-Ronnie James Dio

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                • #9
                  Originally posted by Sea Fury View Post

                  Chevrolet had the DOHC LT5 V8 in the Corvette ZR1.
                  Made by Mercury Marine.

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                  • #10
                    And designed by Lotus.
                    "I would really like to go to NASCAR. I really enjoy NASCAR and if I could be there in a couple of years that's where I'd want to be." - Jeff Gordon (after testing a Formula Super Vee)

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                    • #11
                      And Cadillac had the Northstar DOHC V8.
                      "Only a fool fights in a burning house."-Kang

                      "If you listen to fools....The Maaahhhhb Ruuuules....."-Ronnie James Dio

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                      • #12
                        Spike , comments on your post. The Buick/Menard V-6 was used until new chassis and engine package by IRL starting in 1997. The Brayton engine was a V-8. My recollection is Menard had to run the V-6 because of contract issues with Buick. Not sure what the announcement of the IRL had on the development of the Brayton V-8. Also Brayton was supplier of the Olds aurora V-8 starting in 1997. Not sure if it was similar to the Brayton V-8.

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                        • #13
                          Originally posted by raschu75 View Post
                          Spike , comments on your post. The Buick/Menard V-6 was used until new chassis and engine package by IRL starting in 1997. The Brayton engine was a V-8. My recollection is Menard had to run the V-6 because of contract issues with Buick. Not sure what the announcement of the IRL had on the development of the Brayton V-8. Also Brayton was supplier of the Olds aurora V-8 starting in 1997. Not sure if it was similar to the Brayton V-8.
                          The Olds was a DOHC engine, so it probably wasn't related to the Brayton, which was made for the pushrod rules.
                          "Only a fool fights in a burning house."-Kang

                          "If you listen to fools....The Maaahhhhb Ruuuules....."-Ronnie James Dio

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                          • #14
                            Originally posted by raschu75 View Post
                            The Buick/Menard V-6 was used until new chassis and engine package by IRL starting in 1997.
                            Yep. As I mentioned in post #6 he Brayton/Menard engine couldn't be used due to it having been rendered uncompetitive by the rules changes made after the '94 season.

                            =raschu75;n6569476The Brayton engine was a V-8.
                            Yes, I mentioned that both the Brayton and Greenfield engines were V8s in post #6.

                            Originally posted by raschu75 View Post
                            Menard had to run the V-6 because of contract issues with Buick.
                            No, Menard had pretty much bought what remained of the Buick V6 engine development program and continued the development in-house and his engines were thereafter referred to as being Menard V6s.

                            Originally posted by raschu75 View Post
                            Also Brayton was supplier of the Olds aurora V-8 starting in 1997. Not sure if it was similar to the Brayton V-8.
                            That engine was loosely based on the architecture of Northstar 4.6 liter V8 mentioned in post #11.




                            "I would really like to go to NASCAR. I really enjoy NASCAR and if I could be there in a couple of years that's where I'd want to be." - Jeff Gordon (after testing a Formula Super Vee)

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                            • #15
                              My (probably quite jaundiced view): Penske thought, "Pushrods? Ok, we will install pushrods - too bad for others and good for us you didn't stipulate how long they had to be."
                              I stand to be corrected.

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