Engine Swap: Which Would You Choose!??

[3MI Racing]

Originally Posted by LSxJunkie

Nice thing about those Fox body motors, you blow one up and you get another one for like 150 bucks.

I'm hoping he meant the Coyote

[Dimman]

Originally Posted by 3MI Racing

I'm hoping he meant the Coyote

Vanilla Ice's 5 point Oh didn't have overhead cams...

[fatoni]

Originally Posted by Dimman

Vanilla Ice's 5 point Oh didn't have overhead cams...

dont be stupid. every body knows ice rides a bike

[ZDan]

Originally Posted by LSxJunkie

What's the compression with the milled heads, what's the LSA on that cam, and what cam profile did you go with?

I didn't build it, so not 100% on specifics. The L92 heads were shaved to 64cc, supposedly 11:1 CR.
Cam was by PatG, 222/230 .597", lobe separation 114 I think...

We took it to the San Antonio drag strip when I was down to pick the car up , PO did a 11.69 @ 129.16mph
Neither of us is a drag racer, and the car is a daily-driver/HPDE compromise, so highish ET for the mph...

[LSxJunkie]

Originally Posted by ZDan

I didn't build it, so not 100% on specifics. The L92 heads were shaved to 64cc, supposedly 11:1 CR.
Cam was by PatG, 222/230 .597", lobe separation 114 I think...

We took it to the San Antonio drag strip when I was down to pick the car up , PO did a 11.69 @ 129.16mph
Neither of us is a drag racer, and the car is a daily-driver/HPDE compromise, so highish ET for the mph...

129? Car should go low 11s on a drag radial with a some practice. I like the cam for road racing though, even though it's a little light on the intake duration. With the wide-ish LSA, I'm sure it idles real well though.

[serialk11r]

Originally Posted by LSxJunkie

Yurp. Who needs more than one cam?

Really? :P
People are quick to criticize the torque delivery of small displacement Japanese engines, but if you look at that torque curve, it's not exactly what you'd call good. You are seeing 75% peak torque at 2000rpm on a 5000rpm peak, which is rather pathetic. A 2GR-FSE has almost 100% torque at 2000rpm with a similar peak. People are complaining about a ~10% dip in the midrange on the FA20, whereas that LS2 never even hits 90% peak torque until over 4000.

[ZDan]

Very one-dimensional view there, serialk11r...

Flat torque curve isn't as important as making as much torque/power as you can, wherever you can make it, while maintaining streetability (in this engine's case, anyway). Would it be "better" if it simply plateu'd at 2000rpm? According to you, I guess it would be. For me, NOT.

Suffice it to say, there's plenty of oomph at all rpm...

[serialk11r]

What I'm getting at is peak torque is making the most power at a given engine speed. Sure, flatter torque curve isn't better if it's overall less torque, obviously, but specific torque on the LS2 isn't any better than said Japanese motors, so the Japanese motors are making better specific torque most of the time, despite having the big rev range disadvantage. That's what "torque delivery" is right? It's not about "enough power" or not, it's how much of the engine's potential is being extracted across the rev range. The LS2 is obviously much more powerful than a F20C, but if the car's size is matched so the peak acceleration is the same, the F20C will feel more consistent than the LS2.

Not to diss the LS motors, it's very admirable that GM understands that cost effective >>> bragging rights (I think Japanese companies sometimes need to get their priorities straight, Honda S2000 would be a good example, they want to use a 2L engine to get huge amounts of power, and then they toss the only advantage a small displacement engine has out the window by giving it gearing unsuitable for the street), funny saying that about the company that is staying afloat on taxpayer money.

[EJ20]

EJ2x all the way

[Dimman]

Originally Posted by ZDan

Very one-dimensional view there, serialk11r...

Flat torque curve isn't as important as making as much torque/power as you can, wherever you can make it, while maintaining streetability (in this engine's case, anyway). Would it be "better" if it simply plateu'd at 2000rpm? According to you, I guess it would be. For me, NOT.

Suffice it to say, there's plenty of oomph at all rpm...

What he's getting at is that displacement being equal a 4v head will rock a 2v head in torque output. Has to do with flow area (which is based on valve circ.) which requires less cam duration and pushes up the low and midrange. Plus add in tech like cam phasing which gives dynamic LSA control and it's no contest.

But GM is quick to point out that all that stuff is expensive and also bulky (ohv heads are surprisingly small).

Always the damn compromises...

[ZDan]

Originally Posted by serialk11r

specific torque on the LS2 isn't any better than said Japanese motors

No reason it should be, of course. Smaller combustion chambers should have a specific torque advantage due to higher CR. But hey, this big-cylindered LS made 79 rwlb-ft/liter to the wheels!
(To be honest, I think the 517hp/473 lb-ft numbers are really closer to flywheel than actual rear-wheel)

so the Japanese motors are making better specific torque most of the time, despite having the big rev range disadvantage.

First I've heard having a big rev range being a *disadvantage*! FWIW, the FR-S/BRZ's rev range advantage over my LS is only 200-400rpm, I'm limited to 7200 in 1st-3rd, 7000 in 4th-6th (as if it could get to 7000 in 6th!).

That's what "torque delivery" is right? It's not about "enough power" or not, it's how much of the engine's potential is being extracted across the rev range.

If you only have 2.0 liters, n/a, there's a much greater NEED to make near peak torque everywhere. It's no secret that multivalve cylinder heads have an advantage filling cylinders over a broader rpm range. You can get relatively more flow per engine size with less valve lift and overlap.

The LS2 is obviously much more powerful than a F20C, but if the car's size is matched so the peak acceleration is the same,

Well, now, *that's* no fun, now is it! That would be about a 6000 lb car, btw...

the F20C will feel more consistent than the LS2.

Don't get your point here, really. Don't really care what my LS2 feels like in a 6000 lb. monster. It feels pretty sweet in a car that weighs barely any more than the S2000

Not to diss the LS motors, it's very admirable that GM understands that cost effective >>> bragging rights

*ALL* cars are compromises, *ALL* engines are compromises. The LS happens to be a *brilliant* compromise. With DOHC and 4v/cyl, they could get closer to peak torque over a broader range. But that doesn't only add to cost, it would add significantly to size and weight and c.g. height. ALL BAD THINGS! Another way of looking at it: for the same V8 engine size and weight, you could have 4 liters with DOHC/32 valves, or 6+ liters cam-in-block/16 valves. The 4 liter might make closer to its peak torque over a broader range, and rev higher, but enough to make up for the displacement disadvantage? No...

(I think Japanese companies sometimes need to get their priorities straight, Honda S2000 would be a good example, they want to use a 2L engine to get huge amounts of power, and then they toss the only advantage a small displacement engine has out the window by giving it gearing unsuitable for the street),

I like it the way it is: uncompromised. Plus you get decent passing acceleration without downshifting

Anyway, I'm a HUGE fan of GM's approach with the LS engines, vs. Ford's monstrously huge, heavy, and high-c.g. V8s. When I get around to doing a Factory5 Daytona Coupe, it's definitely going to be with an OHV 347 stroker, noy a DOHC/32-valve mod motor.

[ZDan]

Originally Posted by Dimman

What he's getting at is that displacement being equal a 4v head will rock a 2v head in torque output. Has to do with flow area (which is based on valve circ.) which requires less cam duration and pushes up the low and midrange. Plus add in tech like cam phasing which gives dynamic LSA control and it's no contest.

Just saw this, but addressed it above I think...

But GM is quick to point out that all that stuff is expensive and also bulky (ohv heads are surprisingly small).

EXACTLY. The 90's "ZL-1" learned them their lesson: A few more ponies for a LOT more weight in all the wrong places, for a lot more $$$, ain't worth it. There are better ways to making more power if you aren't displacement-limited.

Always the damn compromises...

I love it! It gives rise to a VARIETY of different approaches.

Like when F1 didn't suck and featured V8s vs. V10s vs. V12s. They all had their strengths and their weaknesses.

[serialk11r]

You think 2 liters is not a compromise ZDan?
The only reason they made the F20C 2L was because Japan has displacement tax. If they wanted no compromise they would've given it a bigger bore from the start. Don't get me wrong, the S2000 is awesome, but it's definitely got a bit of a conflict in design philosophy. It's like a racecar on one hand with extremely short gears, fantastic performance, on the other hand it's massively handicapped by a displacement chosen for tax reasons. No replacement for displacement is sadly true.

Rev range is a disadvantage for torque delivery, but not power, of course. The bigger the difference in engine speeds that you have to run at, the harder it is to optimize things.

And no duh, the LS2 will feel great despite less than ideal torque characteristics because it's just got SO much power, and knowing how compact and light the engine is for its size, that's definitely something to brag about. Personally I think a street performance engine shouldn't go the brute force high displacement method, but it has very strong merits for sure.

My personal engineering perspective preferences are ~8500-9000 rpm, light boost, low displacement, and moar gears in any transmission that lets me control the clutch. SCed 2ZZ with slightly tightened up 1-6 gears and a quiet and extremely efficient 7th

[Dimman]

32v ohv SBC??? Could they fit in 16 more pushrods? Or split the rocker arms to push 2 valves? Someone somewhere must have tried this...

Super compact large displacement with better filling, cam phasing be damned.