I have completely worn myself out on this topic. So I am going to stick to my guns this time and make this my last post about the “off topic” topic. I have five days off from work, I have out of town guests and I am going to try to relax. Why do I need to relax? Because this thread has derailed into me apparently being signed up to fight a battle I don’t support. This started out with Graham poking fun at me about the pushrod engine in the GT2 Corvette. I initially tried to focus on race engines, but somehow this has bled over into a battle over road car engines which can (and has in this thread) becoming a religious discussion. My willingness to be involved in religious discussions is generally pretty small.
I am also sad that Jason didn't even comment about the photo of his clone up above.
Jason Mauldin wrote:
Richard Casto wrote:
Agree with you somewhat. I don't think the pushrod design choice is what makes the Corvette good. I am not sold on the "lighter package" and "lower center of gravity" arguments.
Find a lighter engine that produces the same hp, in a non-exotic car.
I am also not saying that the current Corvette engine is not light, or that a pushrod engine can’t be light. One of the advantages is that they can be light due to the design being simpler and having fewer parts. The current Corvette road car engine is VERY light for the power it puts out. No argument from me. My point above is that I don’t think that “lighter and lower” were the main reasons they picked a pushrod engine for the Corvette road car. I am sure it was part of the equation, but not the main factor. Once it was picked I am sure they spent time and money on how to make it light and low.
But what I am really talking about is racing engines in which you don’t start with a given HP and then figure out what design gives you the lightest engine. You typically start with a given displacement (and sometimes configuration such as “V8”) and go from there. My point is that if you are building a bespoke racing engine, NOBODY builds a pushrod engine unless they are forced to do so by the rules. Someone please show me an example otherwise?
Jason Mauldin wrote:
Richard Casto wrote:
I think those same two goals could be achieved in other ways.
For example???
In a racing engine? Material choice to reduce weight and angle between cylinders for center of gravity.
Jason Mauldin wrote:
Richard Casto wrote:
I still believe that GM is using the pushrod engine for the reasons I list. The others just end up being freebies that come along for the ride and are viewed after the fact as justification for the pushrod design.
Let's not forget that GM also designed this engine for their trucks which are likely sold 10:1 to their v8 powered cars. Honestly, your reasons are probably not even in the top 5 reasons why GM still uses the superior pushrod engine.
I bet it starts more like this.
1) Cost
2) Ease of manufacturing
3) Use of existing knowledge base
The three you list are all “cost” (which was one of the two reasons I listed.) I also didn’t say my list was in priority order. Cost may be the #1 factor. If in the future the Corvette happened to be the very last product that used a pushrod engine at GM, then the “cost” factor would be working against them. I didn’t say it at the time, but that is why I think that eventually the Corvette will get an OHC engine. I may be 10, 20 or 30 years from now, but the pushrod engine will just not be the right engine for the car at some point. Time will tell if I am right or wrong. Feel free to look me up in 30 years and tell me I am wrong.
To continue with the “Historic continuity of identifying feature” factor, I would point to the material used for the body as well as the transverse spring used in the rear suspension (not 100% sure that is still used) would fall into that category as well. Cost and plain old engineering decisions factor in as well. I think there are good reasons for the body material choice, probably less good reasons for the spring on the rear, but I believe the that these two items are features of the car that are identifiable as what makes a Corvette a Corvette. The Marketing, Design and Engineering teams keep those features alive from one generation to the next.
We will just have to agree to disagree on why GM makes design decisions. It is just an opinion on my part and I could be wrong. But it’s still my opinion. And I am really sorry that this ended up as being so focused on the Corvette road car. It is a great car and GM is clearly doing something right with it. I would love to have one.
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Richard Casto
1972 Porsche 914
2013 Honda Fit Sport
2015 Honda Fit EX
http://motorsport.zyyz.comMoney can't buy happiness, but somehow it's more comfortable to cry in a Porsche than a Kia.