Is 11.5:1 CR Typical for DI Engines?

[IndyIan]

Originally Posted By: supton
Originally Posted By: racer12306
Do these cars need over 300HP?


Do they need 300hp? To be competitive, yes. To get the job done, outside of sales, no. My opinion, of course. But it can be nice to ones foot into it and have results now.

I suppose some pickup truck buyers who may tow care about 270 vs 300hp, but I think most people don't. I bet nearly all of the fwd vehicles with the big V6's don't allow full throttle anyways in the first few gears. In my research on VQ40 Nissan SUV/truck, I learned that even they don't allow over 80% throttle below 40mph...
I think once you have manufacturers reducing hp levels to keep the vehicle drivable, we probably have enough hp!
250hp with some extra torque down low and better mileage would be fine for me in any fwd vehicle I can think of.

 

[SubLGT]

Originally Posted By: ExMachina
……..Since the GM LFX 3.6L V6 (same 11.5 CR) produces 323 hp (no turbo either), then a 3.5L Honda should be getting 300 hp, no excuses except if tuning for fuel economy (more torque) then 290 hp should be reachable.


Looks like GM has been busy with new V6 engines. For Cadillac (and others?) they have the DI, DOHC 3.6L LGX, with 335HP and 284 lb-ft.

"…….The new 3.6-liter LGX engine, which is a clean-sheet design and shares very little with GM’s current 3.6L V6 LFX engine, delivers an SAE certified 335 horsepower and 284 pound-feet of torque. It retains the aluminum deep-skirt cylinder block of the LFX mill, however the bore has been enlarged from 94mm to 95mm and the bore centers have grown from 103mm to 106mm. There’s also an all-new cylinder head design, a forged steel crankshaft, high-strength connecting rods and pistons and oil-spray piston cooling…………."

http://gmauthority.com/blog/2015/03/cadillac-rolls-out-new-3-6l-v6-engine-for-ct6-cts-ats/

 

[InfmousCornholio]

Originally Posted By: Swift101
I don't think DI has anything to do with it. My Sonata 2.0T (DI) has a compression ratio of 9.5:1


Also, remember that lower compression ratios are more ideal for turbocharging than high.

Perhaps this is how these turbo cars can run well on regular 87 octane gasolines, though every turbo I have owned has felt progressively better as the octane on the gas was increased.

 

[skyactiv]

The currant Mazda3 has a 13.0 to 1 compression ratio.
The same car in Britain has 14.0 to 1 because they don't have our crummy 87 octane we are addicted to.

 

[SubLGT]

Originally Posted By: ExMachina
11.5 is very typical, unless we are talking about Mazda, who has performed miracles at 14:1 now……………..


I assume the Mazda requires premium fuel?

 

[badtlc]

Originally Posted By: SubLGT
Originally Posted By: ExMachina
11.5 is very typical, unless we are talking about Mazda, who has performed miracles at 14:1 now……………..


I assume the Mazda requires premium fuel?


"requires"? No. Runs much better on premium? Yes.

 

[hattaresguy]

The rumor mill on the truck forums is saying the Pentastar might be getting boosted and DI soon.

FCA seems to be liking what Ford is doing and is going to follow suite.