Lightest and smallest way to 400 reliable hp.

How hard is it to make 400 in an acvw? Gotta be the smallest thing this side of a crotch rocket. 

Are we still talking about the Mazda F2T?

In reply to mndsm :

reliably I would say yes

I'd be really curious to see a comparison of a modern-ish, all-aluminum DOHC 4cyl/turbo (EcoTec, EcoBoost, MZR, SR20) vs an aluminum LS. The physical dimensions, weight, and cost of all associated components plus dyno charts would probably prove interesting. Somebody should start an engine swap thread where we can include known data.

In reply to pres589 :

That's another good one. Not quite as light though,  and if cheap was out of the equation.....there's better options.  

Turbo Hayabusa.

But LS is the right answer

LSx aluminum block is really popular and one-stop shopping.

I continue to lean towards Ford 302 with an aluminum top-end kit, at least where EFI setups are concerned.  But it's a lot more time scrounging the parts to get it together on a budget, and 20HP less, just to save about 75-100 pounds.  Probably not worth the hassle.  But I keep trying to convince myself it is.

You guys need to take more into consideration than just peak power. I've got dyno charts of an LS3 and a turbo 2.0 that make very similar peak power but there's a dramatic difference in area under the curve. I didn't weigh the turbo car, but I suspect the weight difference between the cars is mostly in the transmission required to hold up to that big engine.

The LS is popular for a reason. It's compact, it's incredibly well supported and it's just so easy.

In reply to JBasham :

Dude, 75-100 lbs is YUGE off the nose of a car. I moved a 40lb battery to the passenger rear footwell and it was significant, yo!

Keith Tanner said:

It's compact, it's incredibly well supported and it's just so easy.

All the things we want...... in an engine 

Turbo rotary?

wvumtnbkr said:

Turbo rotary?

He said reliable, not hand grenade with the pin pulled

Keith Tanner said:

You guys need to take more into consideration than just peak power. I've got dyno charts of an LS3 and a turbo 2.0 that make very similar peak power but there's a dramatic difference in area under the curve. I didn't weigh the turbo car, but I suspect the weight difference between the cars is mostly in the transmission required to hold up to that big engine.

The LS is popular for a reason. It's compact, it's incredibly well supported and it's just so easy.

I'm not saying anything in your statement is wrong, but I just finished watching a video comparison of the current 911 Turbo and the current Audi R8 v10.

The Porsche of course, has a smaller displacement twin turbo flat 6, and the Audi has a larger, high revving, NA V10. Peak HP was the same, but the P car had 80lb-ft more torque, and it started at 1800rpm vs the Audi's peak over 4000rpm.

In this case,  The smaller displacement, turbo engine had more torque through a couple thousand more rpms than the larger NA engine. And it started at a much more accessible rpm range. Ford did the same thing with their EcoBoost v6 vs the Coyote. So a well designed turbo setup can actually generate more peak torque and have larger area under the curve than a big NA engine. 

In reply to STM317 :

Absolutely.  But that tends not to be the case with turbo setups that are pushed pretty far (especially those done on a budget), as they often involve big, slow spooling turbos and low compression, leading to a lack of low end power. 

Regarding DOHC I4 (1.8L) vs OHV V8 (6.2L) physical size:

For 400+hp, I know which I'd rather have.  The problem with I4 size is that they still need a place to hang the intake manifold, exhaust manifold, and starter/accessories that is almost entirely outside the envelope of the engine itself.  The V8 shape largely allows these things to be placed within its recesses.  Not to mention that OHV architecture is naturally much more physically compact than OHC, even if at the expense of some (overrated) volumetric efficiency.  The only dimensional advantage I can think of for a turbocharged DOHC V6 vs a pushrod V8 is in the length department.

Driven5 said:

Regarding DOHC I4 (1.8L) vs OHV V8 (6.2L) physical size:

For 400+hp, I know which I'd rather have.  The problem with I4 size is that they still need a place to hang the intake manifold, exhaust manifold, and starter/accessories that is almost entirely outside the envelope of the engine itself.  The V8 shape largely allows these things to be placed within its recesses.  Not to mention that OHV architecture is naturally much more physically compact than OHC, even if at the expense of some (overrated) volumetric efficiency.  The only dimensional advantage I can think of for a turbocharged DOHC V6 vs a pushrod V8 is in the length department.

Wow, that's a very telling photo. I wonder what the true weight difference is between those two engines fully loaded.

I'd bet with the apropriate sized turbo, you could get 400hp out of a BMW B38:

It's basically that Nissan 3cyl, but in actual road cars.

What criteria are we using to determine reliability?  Hours on track?  Street miles?  Passes at the drag strip?  Autox runs?

I wonder about one of these ->Link   with boost.  Or, bolt two of them together for a v8.

STM317 said:

Keith Tanner said:

You guys need to take more into consideration than just peak power. I've got dyno charts of an LS3 and a turbo 2.0 that make very similar peak power but there's a dramatic difference in area under the curve. I didn't weigh the turbo car, but I suspect the weight difference between the cars is mostly in the transmission required to hold up to that big engine.

The LS is popular for a reason. It's compact, it's incredibly well supported and it's just so easy.

I'm not saying anything in your statement is wrong, but I just finished watching a video comparison of the current 911 Turbo and the current Audi R8 v10.

The Porsche of course, has a smaller displacement twin turbo flat 6, and the Audi has a larger, high revving, NA V10. Peak HP was the same, but the P car had 80lb-ft more torque, and it started at 1800rpm vs the Audi's peak over 4000rpm.

In this case,  The smaller displacement, turbo engine had more torque through a couple thousand more rpms than the larger NA engine. And it started at a much more accessible rpm range. Ford did the same thing with their EcoBoost v6 vs the Coyote. So a well designed turbo setup can actually generate more peak torque and have larger area under the curve than a big NA engine. 

I'm basing my statement on my own testing. I've actually driven all four of the cars below and I own three of them.

1.6 turbo Miata with a small turbo vs 2.0 naturally aspirated Miata. It's the same basic engine, although the naturally aspirated engine runs a better ECU. The turbo graph is not corrected because that setup is fuel-limited and it would have the same peak at sea level. Note that this turbo is selected for response and not massive power, it peaks at about 230 rwhp. These two engines make the same peak power, but check that torque at 3000 rpm. The midrange drop went away with a VVT version of the engine and I believe it was an artifact of the cams - but even then, it only drops down as far as the turbo car. This was a $3400 bolt-on Voodoo II turbo kit vs an engine that would probably cost $15k to duplicate, so there's that. Still, we're just looking at behavior and not value for dollar in this example.

I only have this as a PDF, so click to see. Click me! Click me!

We don't share this one much, because we like selling turbos. But seriously. A 260 lb-ft difference at 3000 rpm. Price to build is about the same, but you'll actually have an easier time with emissions on the V8 and it's got that nationwide two year warranty. It's also chugging 91 octane fuel instead of E85.

You can compensate for displacement somewhat with a turbo, and if you do it well you can do pretty well. The Audi vs Porsche counterexample is valid, although it's a 3.8 vs a 5.2 instead of a 2.0 vs a 6.2. This is why you need to look at more than just peak numbers. Turn up the boost just a smidge more on that 2.0 and you could match the peak power, but you won't match that torque. 

I'm just going to throw this out here... evo 4g63 + r154 or t56 + slightly bigger turbo + bolt ons and tune. My buddy putting out 389whp on his evo and had been for almost 100k miles.

Sr20det can do it too. All about the tune. 

In reply to yupididit :

Rb11 will too, as much as I despise the evox.

4b11 lol. Rwd options aren't really out there for it. I do like the 4b11t over the 4g63t to be honest. 

In reply to yupididit :

4b, rb,  Gallo 24, whatever. 

In reply to yupididit :

incorrect. ThetaII in the Gen Coupay is same block. But it won't be cheap because they used cheap internals.