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Knurled
Knurled MegaDork
10/6/16 12:03 p.m.
kb58 wrote: I'll bit - I don't understand doing 99% of the work to install a V6, when going to a less-stressed V8 is just 1% more effort. I get it that it (probably) weighs less, and is (probably) less expensive, but these cars aren't Formula V's, and what's another 30 lbs when you've got 430 hp.

Don't get me wrong, V8s are fine for some things, but not a sporting vehicle. Unless it is a nice small V8 in the 3-3.5l range.

SVreX
SVreX MegaDork
10/6/16 12:12 p.m.

In reply to Knurled:

I think that presumes a lightweight car.

The RX8 curb weight is between 3000 and 3200 lbs from the factory. That's a nearly 1000 lb disadvantage to the Miata.

It's a solid chassis GT touring chassis that won't be significantly compromised with a V8 if you can make it work.

If you can afford an aluminum block LS, the weight will be nearly identical (though the CoG will change a little).

I think the 8 needs the grunt that a V8 can give.

Knurled
Knurled MegaDork
10/6/16 12:20 p.m.

I don't think it's a weight thing, it's a powerband thing. Inexpensive V8 have too much too soon, and a V8 that revs to 9-10k is going to be one expensive motor.

It's kind of the opposite of putting a turbo D16 in a 1-ton Dodge. Sure, it might make the same horsepower as the V10 you took out, but it's the wrong flavor of horsepower for the job.

Feel free to build a truck-motored sporting car. Chevy seemed to sell the heck out of them in the 70s and 80s

Stefan (Not Bruce)
Stefan (Not Bruce) MegaDork
10/6/16 12:23 p.m.

In reply to Knurled:

And the 90's, 00's and 10's

Robbie
Robbie UltraDork
10/6/16 12:55 p.m.
Knurled wrote: Feel free to build a truck-motored sporting car.

didn't audi win with them?

JBasham
JBasham Reader
10/6/16 1:31 p.m.

I have a BMW S65 V8 in its native GT sedan chassis with an 8400 redline (well, ECU rev limiter) and 400+ crank HP; max torque is available for most of the rev range, and I wind it way out on the track. Amazing fun but ugly front-end cost.

I have a cammed Ford 302 swapped in a lighter GT car with a 6250 ECU rev limiter and about 280 crank HP; torque is about equal quant but peaks at 3.5k and is down 25% from peak by 5k. So I short/low gear it on the LSD end and shift early on the track. Yeah it's less powerful and less efficient. Still, not to quote The Donald, but "There's no problem down there, I assure you."

I haven't done the LS thing thus far, just because the cost of entry and the weight penalty from the associated transmission are not to my taste, so I just suck it up and deal with the lack of horsepower in the Ford package. Light chassis cars rule in my book anyway.

That being said, a motor like this Chevy V6 has never crossed my radar before and it really has me thinking. Effin' 325HP, 350 pounds maybe, I can get one with 30K on it for like $1500, and I don't even need room in the engine bay for headers? DHOC, redlines just under 7k, flat(ish) TQ curve? Damn, I gotta get my head out of the 80's and see what's going on these days.

thatsnowinnebago
thatsnowinnebago SuperDork
10/6/16 1:51 p.m.
Knurled wrote: I don't think it's a weight thing, it's a powerband thing. Inexpensive V8 have too much too soon, and a V8 that revs to 9-10k is going to be one expensive motor. It's kind of the opposite of putting a turbo D16 in a 1-ton Dodge. Sure, it might make the same horsepower as the V10 you took out, but it's the wrong flavor of horsepower for the job. Feel free to build a truck-motored sporting car. Chevy seemed to sell the heck out of them in the 70s and 80s

I uh, kinda want to see someone do that swap

Tyler H
Tyler H UltraDork
10/6/16 1:55 p.m.
JBasham wrote: That being said, a motor like this Chevy V6 has never crossed my radar before and it really has me thinking. Effin' 325HP, 350 pounds maybe, I can get one with 30K on it for like $1500, and I don't even need room in the engine bay for headers? DHOC, redlines just under 7k, flat(ish) TQ curve? Damn, I gotta get my head out of the 80's and see what's going on these days.

It really is a fun engine. Espcially 300+hp in a plain brown wrapper 2013 rental fleet Impala.

Bobzilla
Bobzilla UltimaDork
10/6/16 1:59 p.m.
Knurled wrote: I don't think it's a weight thing, it's a powerband thing. Inexpensive V8 have too much too soon, and a V8 that revs to 9-10k is going to be one expensive motor. It's kind of the opposite of putting a turbo D16 in a 1-ton Dodge. Sure, it might make the same horsepower as the V10 you took out, but it's the wrong flavor of horsepower for the job. Feel free to build a truck-motored sporting car. Chevy seemed to sell the heck out of them in the 70s and 80s

Building an 8k rpm "truck motorer" V8 is a cam and valve springs away with the 4.8. Short stroke FTW. You want to go crazy, use the 4.8 dimension forged crank/rods in the aluminum 6.0L block, correct cam and valve springs and you got yourself a nice 9k redline pushrod V8 that makes power up top.

There have been tons of "truck motors" that turn serious rpms and make all of their power in the upper rpm ranges. Check the old Ford Cleveland 4V's. Intake ports that size required rpms to pull fule and air into those things.

NickD
NickD Dork
10/6/16 2:15 p.m.
Tyler H wrote:
JBasham wrote: That being said, a motor like this Chevy V6 has never crossed my radar before and it really has me thinking. Effin' 325HP, 350 pounds maybe, I can get one with 30K on it for like $1500, and I don't even need room in the engine bay for headers? DHOC, redlines just under 7k, flat(ish) TQ curve? Damn, I gotta get my head out of the 80's and see what's going on these days.

It really is a fun engine. Espcially 300+hp in a plain brown wrapper 2013 rental fleet Impala.

Unfortunately, it's a very trouble-prone engine. Tons of issues with timing chains and tensioners and guides that GM has repeatedly stated they have fixed, yet the problems persist. Also the earlier ones had problems with oil consumption.

dculberson
dculberson PowerDork
10/6/16 2:47 p.m.
Knurled wrote:
kb58 wrote: I'll bit - I don't understand doing 99% of the work to install a V6, when going to a less-stressed V8 is just 1% more effort. I get it that it (probably) weighs less, and is (probably) less expensive, but these cars aren't Formula V's, and what's another 30 lbs when you've got 430 hp.

Don't get me wrong, V8s are fine for some things, but not a sporting vehicle. Unless it is a nice small V8 in the 3-3.5l range.

I like a sporting vehicle to have power; if the v8 has more power than the v6 or i4 then the v8 is better.

Keith Tanner
Keith Tanner MegaDork
10/7/16 12:16 a.m.

Nobody has ever exited one of our V8 Miatas and said "that's just not a sporting vehicle" Unless your definition of a sporting vehicle is personal and has very specific attributes, I think history has shown that many sporting vehicles - some highly revered - have been built with large capacity V8s.

Bobzilla
Bobzilla UltimaDork
10/7/16 3:31 p.m.
NickD wrote:
Tyler H wrote:
JBasham wrote: That being said, a motor like this Chevy V6 has never crossed my radar before and it really has me thinking. Effin' 325HP, 350 pounds maybe, I can get one with 30K on it for like $1500, and I don't even need room in the engine bay for headers? DHOC, redlines just under 7k, flat(ish) TQ curve? Damn, I gotta get my head out of the 80's and see what's going on these days.

It really is a fun engine. Espcially 300+hp in a plain brown wrapper 2013 rental fleet Impala.

Unfortunately, it's a very trouble-prone engine. Tons of issues with timing chains and tensioners and guides that GM has repeatedly stated they have fixed, yet the problems persist. Also the earlier ones had problems with oil consumption.

Also head issues IIRC.

John Brown
John Brown MegaDork
10/8/16 7:34 a.m.

So my work around has come to me from three innocuous statements on two other posts:

1: the NC Miata crossmember bolts in place of the RX8

2; the Mazdaspeed3 makes 263hp from the factory

3: the Ford Ranger 2.5L variant of the MZR engine has a forged crank and great rods and the same exhaust manifold pattern as the MS3.

Off to work some overtime

STM317
STM317 HalfDork
10/8/16 8:18 a.m.
John Brown wrote: So my work around has come to me from three innocuous statements on two other posts: 1: the NC Miata crossmember bolts in place of the RX8 2; the Mazdaspeed3 makes 263hp from the factory 3: the Ford Ranger 2.5L variant of the MZR engine has a forged crank and great rods and the same exhaust manifold pattern as the MS3. Off to work some overtime

Not to throw a wrench in your plan, but there are some differences between the Ranger 4 cylinder and the DISI. First of all, the 2.5L 4 cylinder was a cast iron, SOHC Lima engine with architecture that goes back to the Pintos of the 70s it's not the one you want in this case. The one that you want is the 2.3L aluminum DOHC Durance/MZR that was a mid year swap in 2001. This engine is lighter than the MZR because it has no balance shafts. It also has no VVT or direct injection, which may be an advantage or disadvantage depending on your outlook. The disadvantage is that it would likely result in less power than the MS3 in stock form and increased NVH. The advantage is that it simplifies and lightens the engine.

The Ranger block or head isn't designed for the oil flow needed for the VVT, so you can't just slap the VVT stuff onto the Ranger stuff. The ranger duratec will take boost just fine, but using MS3 fuel system or electronics would probably be more headache than it was worth. I'd start with an NC Miata ECU and look into aftermarket tuners that can reprogram it for boost, and see if you can get the Miata ECU to play nice with the RX8 CAN junk.

TurboRangerForums actually has a lot of Duratec/MZR/DISI knowledge if you get further down the rabbit hole and need help, or want to put a plan together before you jump into this.

John Brown
John Brown MegaDork
10/8/16 8:22 a.m.

2011 and newer 2.5 Ranger is an MZR, not the earlier Lima 2.5.

Wikidikitavi said: Introduced in non-North American markets for the MY2008 and North American markets for MY2009, the 2.5L L5-VE is an updated, bored and stroked version of the L3-VE 2.3L. The 2.5L (2,488 cc (151.8 cu in)) L5 engine has an 89.0 mm (3.50 in) bore and a 100.0 mm (3.94 in) stroke, with a compression ratio of 9.7:1. The standard crankshaft is forged-steel with eight counterweights like the turbocharged DISI 2.3L L3-VDT. To increase durability of the bore, Mazda uses a 4340 steel-molybdenum alloy material for the cylinder liners. This offers enhanced high-heat tolerance as well as reduced friction. The increased stroke of 100 mm (3.9 in), up from 94 mm (3.7 in) of the L3, allows a taller (numerically lower) final-drive ratio resulting in lower-rpm while cruising to increase fuel economy. It also uses iVCT. It produces 170 bhp (130 kW) at its 6000 rpm redline (168 hp (125 kW) in PZEV trim) and 167 lb·ft (226 N·m) of torque at 4000 rpm (166 lb·ft (225 N·m) in PZEV trim). Certain versions are rated at 175 hp (130 kW) at 6000 rpm with 172 lb·ft (233 N·m) of torque at 4500 rpm. Ford has developed an Atkinson cycle variant of the Mazda L5 engine for use in the Ford Fusion Hybrid vehicle. The Atkinson cycle engine was named one of Ward's 10 Best Engines for 2010. Fuel saving features include adaptive knock control and aggressive deceleration fuel cutoff.[6] This and the 2.3 L competed with Toyota's 2.4 L 2AZ-FE engine, sharing similar technology. This engine is built in Chihuahua, Mexico. Applications: 2008–2012 Mazda Atenza/Mazda6 (non-North America) 2009–2013 Mazda6 (North America) 2009– Mazda Tribute 2010– * Mazda Axela/Mazda3 2011– * Ford Ranger 2010– Ford Fusion 2010–2011 Mercury Milan 2012 Lincoln MKZ Hybrid 2009– Ford Escape 2014– Ford Transit Connect
STM317
STM317 HalfDork
10/8/16 8:27 a.m.

In reply to John Brown: 4 cylinders in Rangers came as follows:

Pre 98: 2.3L Lima, SOHC iron block

98-01.5: 2.5L Lima, SOHC iron block

01.5-11: 2.3L Duratec, DOHC aluminum. (It's similar to the NC Miata engine)

If it's an 01 with a 2.5L, it s the iron block SOHC that you don't want. IF it's an 01 or newer with 2.3L, it's the DOHC that you do want

SVreX
SVreX MegaDork
10/8/16 8:33 a.m.
STM317 wrote: In reply to John Brown: 4 cylinders in Rangers came as follows: Pre 98: 2.3L Lima, SOHC iron block 98-01.5: 2.5L Lima, SOHC iron block 01.5-11: 2.3L Duratec, DOHC aluminum. (It's similar to the NC Miata engine) If it's an 01 with a 2.5L, it s the iron block SOHC that you don't want. IF it's an 01 or newer with 2.3L, it's the DOHC that you do want

While that's all very interesting, I believe he said 2011.

John Brown
John Brown MegaDork
10/8/16 8:34 a.m.

In reply to STM317:

I see what you are saying. The 2.5L Ranger engine didn't really make it to the showroom floor.

Submitted for correction in my plan, substitute 2.3 Ranger engine

STM317
STM317 HalfDork
10/8/16 9:00 a.m.

Sign me up as someone interested in seeing it happen. I just didn't want anybody starting a project like based on incorrect info.

John Brown
John Brown MegaDork
10/8/16 9:27 a.m.

In reply to STM317: I'm the king of incorrect information

kanaric
kanaric Dork
10/8/16 12:31 p.m.
Swank Force One wrote: I'd say it's probably mostly heresay. 323hp wouldn't take much boost at all. Usually when you see statements like that, it's when people are disappointed that they can't reliably make 500hp on stock unopened motors. In terms of power, the RX8 is more boost friendly than a 90-05 Miata. Chew on that for a moment or two. But as i said... i like the swap, i'd like to see someone do it. I just don't see the value in terms of dollars and hassle in it just yet.

Yup, people always E36 M3 on like the RB20 as being laggy and terrible, but then they are people trying to make 450hp+ with it.

RXBeetle
RXBeetle Reader
10/8/16 12:36 p.m.

John, I think you're on the right track with the DOHC 2.5L. You just need the FWD varient which happen to be real cheap and pleniful. 2.5L Miata swap

mad_machine
mad_machine MegaDork
10/8/16 1:04 p.m.

you can find that 3.6 from the Traverse for less than a grand on ebay

John Brown
John Brown MegaDork
10/8/16 5:07 p.m.
RXBeetle wrote: John, I think you're on the right track with the DOHC 2.5L. You just need the FWD varient which happen to be real cheap and pleniful. 2.5L Miata swap

Duly noted

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