V8 vs L28/3.1 vs SR20DET

[luckygerman]

I just bought a rust free 73 240z two mos ago and my good friend and engine builder Tony R. we have been discussing various engine options. The V8 is out of the question because being an unibody car your somewhat limited and i think it has been overdone, he has actually converted several himself in the 70's. So I was really turned on by an 3.1 stroker with some triple carbs but he said that the cylinder heads are under-valved and if you wanna make some really good power I should consider the sr20det which I never expect him to say because he is a totally old-school chevy guy that builds allot of the local drag racers engines. Right now he is building a n.a.632c.i. just to give you an idea. So I really respect his opinion. So SR20 it is and according to ebay there are several for sale for around $1600

[Phlebmaster]

First off....Welcome to the forum.

 

You do whatever turns your crank. You will find (as you search around) lots of information about what can be done.

[Guest Rolling Parts]

"rust free" except for the hatch and door frames I guess... LOL.

 

This will wet your appetite for a 4-banger:

http://forums.hybridz.org/showthread.php?t=144738&highlight=sr20det

[BRAAP]

Welcome to HybridZ.

...

The V8 is out of the question because being an unibody car your somewhat limited and i think it has been overdone, he has actually converted several himself in the 70's.

…

 

I don't understand how the unibody is somewhat limited? If a V-8 is a power plant that you may be interested in, something other than the norm so as not to follow the “overdone” approach, take your pick of V-8 and put it back on your list. Infiniti V-8, Toyota V-8, modern or vintage Dodge V-8, Flat head V-8, Indy car V-8, etc...

I would hate to see you ban the V-8 from your list of power plants if the reason is one of those mythical reasons such as “unibody cars have no room" or "a V-8 will wad up the car like a pretzel due to the torque”!

 

Space wise, the Z has a very large engine bays. Big blocks, V-12’s and Viper V-10 have been installed in these cars.

 

Strength wise? On this forum there are big block Chevy’s, my father built a Big Block Mopar 440 Z, the JnJ brothers run a dedicated 8 second drag car with the stock Datsun front and rear suspension, (of course some tube framing), Guys with Turbocharged 6 cylinders running low 8's in the 1/4 mile and the unibody has not complained. In fact, I cant recall one instance where the unibody has complained, twisted, deformed, etc from the engine. Tight suspension and grippy tires and extreme lateral G loads in road racing, now those forces are hard on the unibody.

 

Here are a few examples…

 

Courtesy of jhalsey

 

Courtesy of dot

 

 

 

Courtesy Dat260

 

 

Courtesy of JnJ

[janaka]

^^ Quality post right there.

 

You can add LS1 picture here:

[luckygerman]

Well I never said a V8 couldn't be done and I sure I don't mean to diss anyone with a V8 conversion. I totally Love V8's and even considered an LS1 with a Carb. Totally Love the V10 btw. I actually own one of the biggest import and export business for classic cars in NC and all our cars are V8's. But what I want is 400HP at the wheels. What I like about the SR20DET, that it can be achieved with just 2 liters of displacement and with half the weight then anything out there. It is also very inexpensive, I mean I can pick up an entire power-train tranny and all for as little as $1500 bucks, I couldn't do that with an LS V8 because the Tranny is 2500 alone. I'm also in the middle of restoring 3 other cars so money can't all go in one car, not for now at least

For me the SR20 Just makes the most sense.

[BRAAP]

...

For me the SR20 Just makes the most sense.

 

 

[MAG58]

You know, if you're just looking for 400hp at the meats out back, than the ol' L28ET will do that job just fine. And it bolts in . Don't get me wrong, the SR is a great light motor, but the L6 is currently a pretty affordable platform, very sturdy, maintains that L6 sound, and will have more power under the curve (read driveability) for that same 400hp.

[BRAAP]

..., and will have more power under the curve (read driveability) for that same 400hp.

 

 

I love how displacement bolsters power out side of boost... then just continues to build with boost.

[luckygerman]

I hear ya, well the other importand issue is weight to horsepower ratio and when i drive that thing around the corner I dont want my front-end to wander off. I pretty sure that you are limited with the L28 to 300hp +/- and of course I could turbuocharge it and so on but before I do all that you might as well take use of the lightweight 4banger. From the resarch I have done...with the sr20 the z car becomes a sort of mid-engine car, which is very cool. Diffrent strokes for diffrent folks. I have a 71 chevelle with a 496c.i. 600hp+, a 95merc E420 V8, 66bonneville with a389 v8, so using another V8 dosent get me motivated enough. i actually bought a 78 280z complete that I was going to part out and stroke out but who knows I might get me another Z to have both but it is just to easy to build a 4banger with 400-500hp that kinda gets my blood flowing. If you gus got my site you can see some of the cars we export. Vintagedreamcars.com

it is German but you be able to figure it out.

I'm new Here and this is my first 240z so I'm hear to hear all critics and advice i can get...Z Yaaaa

[280zjoel]

I really like the look of an SR20det in a Z engine bay with a top-mount intercooler. Makes it look purdy.

[MAG58]

I love how displacement bolsters power out side of boost... then just continues to build with boost.

 

Call me old fashioned, but I just don't see the point of RB motors and itty bitty 4 bangers that do actually put out big HP numbers at lots of cool RPM's, but I'd like to have at least some torque to push that thing down the road. I think there was someone who said something about this...Hmm... (see sig).

 

And as far as handling goes, you'd be happily surprised how nimble an L powered Z is on it's feet. Even with that nifty chunk of iron bolted in between the frame rails, it can embarass some pretty impressive machinery with the right setup.

[luckygerman]

Well Formula one uses itty bitty N/A V8 with 2.5Liter displacement pushing 1000HP. Formula one used 4cyl turbo charged engines in the 70's. These SR20 engines make the same amount of torque at 6000rpm than a conventional V8 with half the weight. There is also no question when it comes to reliability, they have proven over the years to be very. and when it comes to Handling performance, why would an engine with half the size and the same power be of any sort of disatvantage, isn't that what every race enthusiast would want to achive?

[neotech84]

+1

WOW in 12 hrs this thread has a few eyes of HBZ big dogs........(not that thats bad)

 

I am glad he is open to the idea and that he seems very open to discussion..... As for the SR20 weight issue its still cast iron/alum head. and is around 490lbs (edit: with tranny) so its like 50lbs at most lighter than a turbo L28. It will be closer to the center of gravity as stated but not the biggest savings.

 

Great post. Hope to see your finished product.

[MAG58]

I'll attempt this as best as I can.

 

I didn't say the handling would be bad with the SR20 in it, I'm saying that the handling with the L28 is still surprisingly good.The car handles wonderfully with the SR in it as well, but to think that the motor design that was originally in the car would create a bad handling car, well just does not make sense to me.

 

And I'm very happy that huge budget teams can make giant power with small displacement engines. HOWEVER, we're not talking about a 1000lb carbon fiber rocket with wheels bolted on. And as far as street engines go, it's just not practical to have a 2.5L engine with a 19k redline (Though that is very cool, so if you can source one go for it). I'm not doubting the ability of the SR to make good power, there are plenty of drag teams that use it to success and heck, even in the GT300 class, Toyota used to swap out the mighty JZ engines for a 3S-GTE, because they got more rules breaks with a turbo 2.0L 4 than a big turbo 6. But on a more realistic note, if you plan on driving it on the street, it's just more livable to have a larger displacement motor running lower boost. And true, a turbo SR engine can make more torque at 6k than a big NA V8, but what about all the RPM's one runs on the street? I usually don't see much above 4k when I'm driving on the street. If this is going to be a dedicated track car that does see the upper rev range a lot, than this argument is useless and you're right, go SR, but if not, I'm just suggesting other routes to the same end goal. I'm not saying one is better, I'm just giving my opinion.

[BRAAP]

I hear ya, well the other importand issue is weight to horsepower ratio and when i drive that thing around the corner I dont want my front-end to wander off. ...

I'm new Here and this is my first 240z so I'm hear to hear all critics and advice i can get...Z Yaaaa

 

 

Power to weight ratio and a good balance front to rear of that weight, very important for sports car. The Z car is an excellent platform for those reasons.

 

I do want to point out something regarding the SR20DET vs the other options. Just because the SR20DET has have the cylinders of a V-8 doesn't mean it will weigh half as much. What you'll find is the SR20DET isn't going to reduce the overall weight of the car by significant amount vs the L-6. Approx the same as going from an empty of gas to a full tank, little less than 100 lbs. Even the Small block Chevy conversion can lighter than the L-6 with strategic aluminum bits.

 

 

I’m not trying to push the V-8 into your car, just trying to dispel some what appears to be some misconceptions regarding various swaps, such as the V-8.

 

The V-8 in the Z car is as much of mid engine cars the four cylinder as they are approx the same length, beauty of the V-8 is its CG is lower than the twin cam 4 cylinder so any weight penalty a V-8 carries, it carries it lower, much lower!

 

Also, the Z car is already 50-50 weight distribution. My first V-8 Z was a small block Chevy, car gained 125 lbs, 50 on the nose 75 on the rear! Moving the CG rearward, 49-51 weight distribution. This was my daily driver and autocross car, I did not notice the weight gain at all, (again, like going from empty tank of gas to a full tank), but I did notice twice the torque and HP output from twice the displacement!

 

Here is that V-8 Z. Note the front the of the engine is at the center line of the front wheels! Could have gone back further in the car if I really wanted it. The car turned corners with authority, (took top time of day at local autocross with 100+ entrants), and still ran a 12.3 @ 113 MPH on garbage 195 60 HR 14” all season tires!

 

 

[280zjoel]

 

hehehe braap i love this picture. It looks like your car is saying, "IM GONNA EAT YOU!!!!"

[John Scott]

So, if this is going to be a strictly race car you have some engines that will be better than others, but maybe only marginally. Are you a good enough driver to realize the difference or is the rest of the car prepared well enough to take advantage of the choice? If its a street car then the line get pretty fuzzy since most platforms can be made to handle better than most cars you can buy.

Heck, even the old 4.3 V6 will give you a real nice rear weight bias and sits really low. As I recall, 17" from the front of the block to the radiator! Shorter and lower than a 4 cyl.

Go with what makes you smile every time you pop the hood.

[luckygerman]

That is a nice V6 Setup, what kinda power are you making with this? Is it an Automatic trans?

[John Scott]

That is a nice V6 Setup, what kinda power are you making with this? Is it an Automatic trans?

 

??. It was a long time time ago '97, stock heads hindered good hp numbers, but ran great at 14 psi, very nimble. Lots of aftermarket parts for better performance, Buick V6 even greater potential. Started with a 700r4, went to a T56. Currently, much more satisfied with with a torquey V8.

Next time who knows. Never done a 4, the sr20 would be a great project.