Why no push rod engine?

[ProDigit]

The truth about pushrod technology is that it isn't nearly as efficient or powerful as ohc tech. This is why GM and Mopar pushrod engines need 6+ litres to make the same power as the the Ford Coyote V8. And as far as diesel performance, diesels are more expensive to buy and maintain, most parts cost a fortune, and they are a lot more finicky with maintenance. Oh they're also slow AF.

Correction: Wasn't as efficient. Times have changed.
Push rods are better at low revs, while worse at high revs. But with a correct gearing the engine doesn't need to go as high in revs. And especially a small body style like the mirage, suffering only low drag coefficient, it would seriously increase the car's effectiveness in the city. The possibility of using taller gears, improves on the engine's efficiency even more!

[Eggman]

I once thought diesels were cool but anymore I'm not drawn to the noisy, stinky engines so I guess I'm biased.

At this point I'm not sure if the discussion is about pushrod or diesel technology.

Can a comparison be made based on displacement?

[javensbukan]

Correction: Wasn't as efficient. Times have changed.
Push rods are better at low revs, while worse at high revs. But with a correct gearing the engine doesn't need to go as high in revs. And especially a small body style like the mirage, suffering only low drag coefficient, it would seriously increase the car's effectiveness in the city. The possibility of using taller gears, improves on the engine's efficiency even more!

Using a push rod setup would eliminate MIVEC would it not?

Also, most OHV designs are limited to two valves per cylinder, which would reduce efficiency over most OHC engines which have at least 4 valves per cylinder (like the 3A9 engines in the Mirage).

Same reason why most small car manufacturers who make small engines also use some form of Variable Valve Technology, something that isn't possible/feasible in OHV-Pushrod engines.

[Pimp_Daddy_Patty]

Correction: Wasn't as efficient. Times have changed.
Push rods are better at low revs, while worse at high revs. But with a correct gearing the engine doesn't need to go as high in revs. And especially a small body style like the mirage, suffering only low drag coefficient, it would seriously increase the car's effectiveness in the city. The possibility of using taller gears, improves on the engine's efficiency even more!

I'm not sure where you get your information, but pushrods aren't even better than ohc at low revs, they are simple nearly as good. Our Mivec provides efficiency and torque production at both low and high revs, where it would only he one or the other with static cam timing.

The only reason pushrod engines exist is because of packaging reasons. Ohc engines require massive cylinder heads, and in V8 format this makes the engines incredibly wide. Especially when you want to make a larger displacement engine. See the 4.6 DOHC v8 below VS the 5.0L pushrod engine on the right.



Another thing regarding pushrod V8s and direct injection. The next v8 to go into the corvette will be OHC. Because the pushrod V8 runs all valve off of one cam, and at the very end, the DI pump also runs off of it, the design is near its maximum regarding fuel flow and pressure, where anymore will see cams actually breaking. Hence the plan to move to OHC engines in the corvette.

[Pimp_Daddy_Patty]

Any perceived increase in low speed power production in modern pushrod engines is a product of displacement and modern cylinder head design. It has nothing to do with how the valves are actuated other than variable timing.

[Top_Fuel]

The only reason pushrod engines exist is because of packaging reasons.

Packaging...and light weight...and simplicity...and reliability...and lower manufacturing costs.


GM is going into OHC V8s and Ford is going into pushrods. What is the world coming to?!?

An Inside Look at Ford’s All-New 7.3L Pushrod V8

[Loren]

Any perceived increase in low speed power production in modern pushrod engines is a product of displacement and modern cylinder head design. It has nothing to do with how the valves are actuated other than variable timing.

This. /Thread

[Fummins]

They probably realized all those timing chains are a pita. Seems most vehicles are becoming more disposable. I think it was a colorado or 1500 silverado that has a belt at the back of the engine that runs an oil pump for some stupid reason. The only way to inspect or replace it is to pull the engine or transmission. smfh.

[Pimp_Daddy_Patty]

Packaging...and light weight...and simplicity...and reliability...and lower manufacturing costs.


GM is going into OHC V8s and Ford is going into pushrods. What is the world coming to?!?

An Inside Look at Ford’s All-New 7.3L Pushrod V8

I'd like to agree with the reliability part, but both ohc and pushrod engines have proven dead reliable in some cases (Honda engines, Chevy LS and LT1 engines) and also complete time bombs in others (chrysler 4.7 SOHC, Hemi pushrod, Fiat 1.4)

[ProDigit]

The truth about pushrod technology is that it isn't nearly as efficient or powerful as ohc tech. This is why GM and Mopar pushrod engines need 6+ litres to make the same power as the the Ford Coyote V8. And as far as diesel performance, diesels are more expensive to buy and maintain, most parts cost a fortune, and they are a lot more finicky with maintenance. Oh they're also slow AF.

Depends on how you look at it,
For small engines, they're indeed slow, because most of their power is down low.
Which means if they can keep up with a gasoline engine on 0-60, they won't at 60-100.
On the other hand, if they had the same size and HP as gasoline engines being equal at 60-100MPH, they would outdo gasoline engines at 0-60.

Diesels have torque. The right diesel sized engine is actually very fast.
Trucks are competing with race cars, because they can.

However, for a Mirage, a 3 cylinder 1-1.3L Diesel engine capped at 75HP, but 120LB Ft of torque, would definitely help.
Then add a small turbo to it with a wastegate, and you have a super efficient engine that probably doesn't even need an intercooler!