engine choices...i need help

[MERCDRAGON]

i am planning on swapping an engine into a '72 240Z and ive narrowed the choices down to two engines but i cant figure which would be a better setup for autocross and other twisties. my choices are an RB25DE tuned to around 250 to 300 hp with the 25det transmission or a t-5 if it will fit, or an all aluminum chevy smallblock 302 with about 300 hp and a t-5. i searched but either theres nothing comparing these two engines or i missed it(sorry if this has been discussed before). cost should be about the same in the end i would think.

[olie05]

well, the v8 is a better candidate for your intentions, because it places the mass of the engine as far back and down as it will go. An inline 6 will have a higher and more forward center of mass relative to the car. If you're going with an all aluminum v8, then the weight difference over an all aluminum I-6 doesn't even come into play.

 

there is some info on the pros and cons of each swap. try searching again, but more for info on each seperate swap instead of a comparison.

 

-Oliver

[AKWIKZ]

I may be wrong here, but I don't know of any aluminium 302 Chevy V8 engines. The C5 and C6 Corvette engines are aluminium block I believe, but they are 350. And from what I have seen, they are not exactly cheap. Now, you mentioned an RB25de. This is the non-turbo version. If you are looking to get 250hp from it, you may have some work ahead of you. Now, if you meant the turbo RB25det, you will have no problem as they come rated at 250 from the factory for the R33 type. If you get an R34, it is rated at 276. As for placement, I have to disagree with the last post a bit. The V8 may very well sit further back, but not lower. All of the V8 swaps I have seen sit fairly high, all things considered. The RB series of engines have a very short block. My RB26 sits easily four inches lower than the original L series did. But here is the thing, it will all come down to personal preference. This kind of comparison is all too common and has been hashed out to death. There are pros and cons to both. There are plenty of people who will tell you how one is better because of whatever. Either one will work. You just need to decide if you like "blondes" or "brunettes".

[Clifton]

If the engine weight were equal and the 2.5 was turbo and the 302 ci was n/a and bothe made the same power. The V8 would be a better choice. Your torque will be available at lower rpm without lag. This would help alot foe auto X.

[dr_hunt]

Dart and donovan make some really nice pieces when it comes to all aluminum sbc. Only 300 Hp? You'd have to build it kind of stock to get 1hp per cube. Some good AFR heads and a mild hydraulic roller would get you that easily. From what I've seen posted the cost of the alum. V8 and the rb motors would be about the same.

 

But since your only looking for 300 then you might stick with the l28.

[Tim240z]

Just drop in an LS1 out of a 1998 and newer F-body.....

[randy 77zt]

if you swap a chevy in it will gain weight in the rear.a local guy did a 240 and fabbed his own mounts .all the extra(not much) ended up on the rear axle.the crank pulley was over the crossmember.am aluminum head 302 ford is lighter than a turbo l28.it all depends on what flavor you like your torque.i have too much money invested in l28 turbo stuff .if i changed to v8 i would go ford 302 with aluminum heads.i would build another crossmember to mount the engine and cut the mounts off of z crosmember.stuff it way back.

[hoov100]

BMW made an all alum DOHC v6/8

 

 

bimmer

[Ed260Z]

Either one will work. You just need to decide if you like "blondes" or "brunettes".

 

Both are good engines to go with. The Chevy would probably be the cheapest when all is said and done. The RB25DET is a JDM motor making its parts harder to get. (and harder to get through state inspection) I like the Nissan engine because I think of it as an evolution of what the S30 had to begin with.

You can make arguments in either direction, but in the end it will be your prefference.

[wheelman]

Another aspect of the question to consider is "What class do you want to run in?"

Sticking with a Nissan motor opens up the Street Modified 2 class in Auto-X where the Chevy engine will put you in a different class with "real" race cars. I'm not very familiar with road racing classes so won't comment. Some of the deciding factor in which class you end up in depends on the local club so check with them rather than relying on any of us. I talked to my local club and was told I'd end up in either SM2 or E-Mod depending on the overall car and how many cars are in either class (no fun to run in a class by yourself). For national competition I'd be in E-Mod because thats where the rules put me due to the LT1 I swapped in.

 

I also second what Tim240Z suggested. Drop in an LS1. It's lighter than the L28, has more power stock than your looking for and a flat torque curve making it very versatile. Hard to beat for the price. Look at posts by Phantom regarding the weight dist. on his LS1 powered Z. His car ended up with a rear weight bias partly due to the light weight of the LS1 and the heavy T56. I swapped an LT1 with a WC T5 into my 240 and ended up with basically a 50/50 weight distribution.

 

Wheelman

[Clifton]

Ya, any motor swap will put you in E mod. If you are mainly after a fast/fun street car first, fun auto x car second it shouldn't matter. Me and a friend run E mod, motor swap, tires ect. Not as fast as most E mod cars but faster than most autocross cars and faster than any car on the street running auto X.

[MERCDRAGON]

i tend to agree with the v8 swap because im going to college full time right now and that would be cheaper, but i wanted to build the v8 in my garage if i did the v8 because my dad and I are building a chevy 383 stroker with afr heads and brodix aluminum block for his '72 Z and i thought it would be fun to build my own engine. i also already have a block available but its one of the cast iron 4 bolts as opposed to my ideal setup with the aluminum block. i also wanted a carb so i didnt have to deal with computers and the fi setup. thanks for all the input so far guys, it helps a lot.

[Ed260Z]

--------i wanted to build the v8 in my garage if i did the v8 because my dad and I are building a chevy 383 stroker with afr heads and brodix aluminum block for his '72 Z and i thought it would be fun to build my own engine.------

 

In that case why don't you have a little competition with your dad, and go with the RB25DET. It will cost about $500 to $1000 more than the Chevy.(Less if you leave it stock) A Mild RB25DET (320Hp) would run around $4-5K if you do all the work your self. It's easy to upgrade as money allows, since the bottom end will hold 500-550 HP easy. And the Tranny can take much more than that.

 

The big plus with the V8 is that the power is very linear, and has a great sound. But hey this is a Jap car, It's suppose to sneak up on you.LOL:burnout:

[240Z_Master]

In that case why don't you have a little competition with your dad' date=' and go with the RB25DET. It will cost about $500 to $1000 more than the Chevy.(Less if you leave it stock) A Mild RB25DET (320Hp) would run around $4-5K if you do all the work your self. It's easy to upgrade as money allows, since the bottom end will hold 500-550 HP easy. And the Tranny can take much more than that.

 

The big plus with the V8 is that the power is very linear, and has a great sound. But hey this is a Jap car, It's suppose to sneak up on you.LOL:burnout:[/quote']

 

Don't forget that thing called Torque!

[Ed260Z]

Don't forget that thing called Torque!

 

OHHHH! Well that's so true the V8 will give you more torque than the RB. So lets not forget to Stiffen the Chassis even with a mild V8 swap.

With the stock RB25DET you should be OK. (pushing it but OK)

[jsap]

Why not SR20DET? It's a lot lighter than RB or V8. It's shorter, so the weight is shifted toward the center of the car more. It can make decent power(300~400HP), and it revs quite happy. Oh, and the parts are easier to find than the RB

[Zhadman]

If you're on a budget... the V8 will give you more for your money.

Don't underestimate the costs (in both time and money) for a swap (whatever the engine choice).

 

The subject of engine weight, position, and effects of handling characteristics has been discussed, ad nauseum, with respect to the different engines out there. It has pretty much been shown that no one engine will give you much of an advantage over another (with respect to these factors).

 

Oh, and the parts are easier to find than the RB

 

SR parts ARE easier to find, but support for RB parts is on the increase. Open any Stupor Street and you will find various advertisers listing parts for the RB. These swaps are 'the new thing' for the S13/14 guys... thus increasing demand for RB parts. I don't think this should be a factor anymore.

 

i also wanted a carb so i didnt have to deal with computers and the fi setup

 

Man... I am the exact opposite. After messing with VW's and Motorcycles (multiple carb setups) I'm pretty much turned off by the buggers. But hey, go with what ya' know!

[Phantom]

The LS1 / T56 conversion added 30 lbs to the back of my 280Z. It started at 1400lbs front / 1400 lbs rear and ended at 1400 lbs front and 1430 lbs rear. THe extra weight and rear bias came from the T56. The LS1 was lighter than the L28. Going with a T5 and a standard cross member rather than the modified torque-tube design used on my car would probably end up with a slightly front biassed wieght distribution that could then be adjusted by moving the battery - mine was still in the stock location.

 

Go to my phot album and look at the dyno run. Of specific interest should be the torque curve. You can see that it is massive and relatively flat from 1500-5500 rpm.

 

Another point - most people talk flywheel Hp when they discuss engine output rather than wheel HP. I assume that is what you meant. My LS1 - straight out of the box - is making 365 flywheel HP out of 346 cubic inches.

 

Racing classes are another story. If you just want to go out and tear up a track and not seriously compete in a specifc class then I'd seriously consider a V8. If your goal is some serious SCCA racing then I'd stick with the stock I6 and put the money into race prepping the suspension and brakes that allow you to compete in a stock class.

[Ed260Z]

Another point - most people talk flywheel Hp when they discuss engine output rather than wheel HP. I assume that is what you meant. My LS1 - straight out of the box - is making 365 flywheel HP out of 346 cubic inches.

 

I'm talking Wheel hp. Crank HP is for advertising, not reality. An RB25DET should get you 350 Wheel Hp with very little changes. This is more than you will get out of the V8 with similar modification, but the Torque will be higher with the V8.

[Guest speedmon]

This is really an interesting thread...for me. I've been tracking a Z06 (02 Corvette with a 400hp LS1 motor) for about 4 years now. Its a great car for the track....it can run at 6500 all day long and never a problem. And it's got 400lbs of torque at 2000 rpms. I have never been able to get the car under 3000lbs though.....which brings me to my point.

 

If you are going to track a car.....power is great....but RELIABILITY is very important as well. The supercharged and turbo cars always tend to heat up after 20 minutes at 6000rpm unless they are full blown race cars. That is why I drive the Z06.

 

I recently bought a Z (240Z) from a friend who needed cash ($5K) and took it to the track. The car has been stripped down to about 530lbs a corner and its pretty quick with 3 liter stroker and 3 mikunis. It handles the turns like CRAP, but I'm working on that. Its always tempting to look for more HP, which seldom the fastest way around the track, but I too have been intrigued by these TT Skyline motors......but so much plumbing and electonics to tune and keep in tune and if parts are an issue then the V8 option sounds pretty good.

 

I can believe the L28 motor wieghs more than the LS1 motor. Do you have the specs on that? (SDPC quotes the shipping weight of an LS1 motor at 520lbs)

 

Something to think about,,,,because for about 6K you can by a new Z06 crate motor which will pump 405hp and rev to 6800 for years and you'll never have to tune it or worry about it melting down.