FB series slant connecting rod. What do you think?

[Ryephile]

Originally Posted by RWD_only

And just because the engine is likely to be undersquare doesn't mean it won't be high revving: the 2zz, B18, K24, and the Lambo/Audi V10 are all undersquare.

Exactly. Undersquare is not related to rod ratio.

[Dimman]

Originally Posted by Ryephile

Exactly. Undersquare is not related to rod ratio.

But 90mm is a long stroke, which will put a TON of stress on the rods at high revs. And for the motor to make good power NA with a 2.0L, it'll need to rev.

[chulooz]

Originally Posted by Dimman

But 90mm is a long stroke, which will put a TON of stress on the rods at high revs. And for the motor to make good power NA with a 2.0L, it'll need to rev.

2.0L with over 200hp that redlines below 7k, it can happen, it does happen.
http://www.rmsci.com/caterhamusa/zetec.html

Also lets not forget about torque. Even current NA subies are fun because of their torque characteristics

[old greg]

Originally Posted by chulooz

2.0L with over 200hp that redlines below 7k, it can happen, it does happen.
http://www.rmsci.com/caterhamusa/zetec.html

You might want to read that again.

[chulooz]

Hahaha good call... it tops out at 7.5k but the thing peaks before redline.

[PAImportTuner]

Originally Posted by Ryephile

Exactly. Undersquare is not related to rod ratio.

Correct.

The rod asymmetrical design revving to 7k rpm with that r/s ratio is is what the topic is about.

FB20 and FB25: 90mm stroke with a rod length of 129.3. 1.44/129.3 rod to stroke ratio. You kinda want a minimum of 1.5 r/s ratio for an engine more if it high revving. 1.74 r/s ratio is an ideal r/s ratio for the street. A 2.0 r/s and above is f1 and supercar territory.


Some info for comparison. I gave the r/s ratios and 89-90mm strokes on the Hondas that had them and then the EJ stroke for comparison to FB.

EJ20 1.74/130.5 75mm stroke
EJ25 1.67/131.7 79mm stroke

Every rod to stroke ratio from Honda is better than the FB20/25 since the 80s.
K20A 1.62/139
K24A 1.54/152
B16A: 1.74/ 134MM
B17A1: 1.62/131.87MM
B18A1: 1.54/ 137MM 89mm stroke
B18B: 1.54/137MM 89mm stroke
B18C1: 1.58/137.9MM
B18C5: 1.58/137.9MM
B20A3 1.50/142.75MM
B21A1: 1.492/141.7MM
B20B: 1.539/137MM
H22A: 1.577/143MM 90mm stroke
H23A1: 1.49/141.5MM
F20C: 1.821/153MM
D17A1: /140MM
D17A2: /140MM
D16Y8: 1.52/137MM 90mm stroke
D16Y7: 1.52/137MM **
D16Z6: 1.52/137MM **
D16A1: 1.52/137MM **
D16A6: 1.52/137MM **
D15B1: 1.59/134MM **
D15B2: 1.59/134MM **
D15B7: 1.59/134MM **
D15B8: 1.59/134MM 90mm stroke
ZC: 1.52/137MM

[Dimman]

Originally Posted by chulooz

Hahaha good call... it tops out at 7.5k but the thing peaks before redline.

It's actually a pretty good example of how the performance version of the FB20 could be from the original.

Bore and stroke and power are pretty similar between the base Zetec and the FB20.

That being said, the performance version is probably close to the edge. Any more power out of it would likely require massive $$$ or boost.

That is why I'm not too keen on a maxed out 200 hp FB20. There may not be a lot of room for more power at reasonable cost.

Something in the 86mm x 86mm would be much better: 3SG(T)E, K20, SR20 all use it (also 2JZ in L6 form). The square 2.0L 4 seems pretty popular for a performance motor. Less stress on the rods for more rev-friendliness, and a bit more potential valve area for flow.

[chulooz]

Originally Posted by Dimman

That is why I'm not too keen on a maxed out 200 hp FB20. There may not be a lot of room for more power at reasonable cost.

I totally agree, that has kind of got me hoping for a turbo release soon after its debut. Usually some good tuning to be had there

[SUB-FT86]

Originally Posted by chulooz

2.0L with over 200hp that redlines below 7k, it can happen, it does happen.
http://www.rmsci.com/caterhamusa/zetec.html

Also lets not forget about torque. Even current NA subies are fun because of their torque characteristics

The N/A 2 liter boxers make weak torque IMHO. 140 lb ft of torque can't feel strong in a 2900+ lb car. My RSX has about the same amount of torque and feels weak as shit, especially with two extra passengers.

[Random_Art]

Originally Posted by SUB-FT86

The N/A 2 liter boxers make weak torque IMHO. 140 lb ft of torque can't feel strong in a 2900+ lb car. My RSX has about the same amount of torque and feels weak as shit, especially with two extra passengers.

I went and test drove a base Impreza a couple months ago and walked away with the distinct impression that I had just driven a brick.

[Exage]

You're not seriously complaining about lack of torque from Japanese stock naturally aspirated 2.0L engines (or 4 cylinders in general) on 3000lb. vehicles???

I think a nice American engine might do, or a Diesel if you want to go nuts...

[Clode]

evolution on ej20

http://www.fhi.co.jp/english/news/pr...10_09_23e.html