sr20 240z handling

[jessejames]

I've searched and I found small pieces of information in different threads but nothing concrete. This might be in the wrong forum but I figured most of you Sr20 guys hang out here. I read in a post from John C. that the cars corners weight shifts back slightly. So were looking at 48F to 52 Rear. I'm not very familiar with the handling of 240z. I had mine on the road for a month before i started the Sr20det swap. My swap is pretty much done. I've just got to tidy up some of the wires. My next point of focus is the suspension. My current is the original suspension. I think I'm going to be installing Groundcontrol coilovers with Koni's. I'm not certain of what spring rates to use. I thought that heavier springs in the front made sense in a front engine car. I read a thread where John C. made a comment about heavier springs in the front making sense for cars with more power. My last car was a first generation MR2 and It was a blast to drive. The mr2 had a weight distribution of 44.5F to 55.5rear. Do you think the 240z will handle like the mr2 at its limits?? the mr2 used to understeer near its limits and then snap oversteer if pushed beyond. My car is going to be a street/ auto X car. At some point in a year or two I would love to compete in the newfoundland targa. I want a fun car to drive. Not a car i'm afraid of. The S2000 was one of the best cars i've ever driven stock. I want somthing predictable and fun while still being a contender at the autoX events. I should also mention that I dont think I will be able to install a rear sway bar in my car. I installed the fuel cell alittle close the diff. Its not been a problem but I fear that a sway bar may not fit. I wont know until later this summer when i get the car on a hoist. Any input would be appreciated.

[johnc]

Do you think the 240z will handle like the mr2 at its limits??

 

No. The MR2 has a low yaw inertia and is easier to spin then a 240Z. I've autocrossed both cars. Chassis setup has a greater affect on how a car handles and behaves then weight distribution. You can take any car and with appropriate suspension tuning make it an understeering pig or an oversteering squirrel.

[jessejames]

thanks for the response Johnc. Do you think heavier springs in the front will be more forgiving? Is there a newer car that the 240z will handle similar too? In your opinion would you still go with the follow:

 

I found this old thread where you state

 

East Coast (generally for faster, smoother tracks)

 

250 to 350 lb. in. front springs.

200 to 300 lb. in. rear springs.

 

50 lb. in. difference in front and rear springs with the rears being softer.

 

25 to 27mm front anti-roll bar.

17mm rear anti-roll bar optional

 

 

Since I probably wont be running a rear sway bar, and my car is a toy car for street/autox.

[johnc]

There are so many questions left open... Please read the FAQs and stickies. The SR20 swap doesn't turn the 240Z into a different car. The same suspension tuning suggestions for an L6, V8, V6, and rotary 240Z are appropriate for your car.

Edited April 2, 2009 by johnc

[AkumaNoZeta]

What having the smaller engines in the Z does is reduce front end weight right? Making it from 50/50 weight distribution to like 46/54, right? Just an example, its probably actually closer to 49/51 in real life, that is besides the general overall reduction in weight.

[johnc]

The SR20DET swap is NOT significantly lighter then a normally aspirated L6. If you move the L6 back about 4" the weight distribution is within 1% of an SR20 install. Please search, this has been covered a number of times.

[AkumaNoZeta]

You're talking more detailed than I was. I said smaller engines in general, not just focused on the SR20DET. Such as the rotary or something. I want the MYT engine, wish I could find one of those.

[240Z_Master]

You're talking more detailed than I was. I said smaller engines in general, not just focused on the SR20DET. Such as the rotary or something. I want the MYT engine, wish I could find one of those.

 

It all depends... that's too general of a question to be answered correctly. And I know this is too general of an answer

[AkumaNoZeta]

Well, another point is that the SR20DET weighs the same as the NA L6 after its all said and done but with the SR20 you can get well over 500 horsepower while I doubt you could even get 500 from a NA L28. Also the SR20 would leave more room in the engine bay to work in and I dont really care for the intake and exhaust being on the same side like on the L6s

[johnc]

while I doubt you could even get 500 from a NA L28

 

350 to 360 is the best I've ever heard for a NA 2.8L.

[AkumaNoZeta]

Which in respect is a good amount for the Z. I have yet to decide what engine I want to run

[jessejames]

i really like the sr20, ive been a few tuned 240sx's. I also love the sound of the stock straight six. I just need to meet more guys with 240z and actually experience different suspension setups. I guess i'm just afraid of making the wrong choice. I think I'm going to order the front 1" sway bar and the red koni's with groundcontrol coilvers. Spring rates F250 R200. Or do you think I should go slightly stiffer?

[Canadianz]

This isnt really relevant to your topic, but how long have you been working on the swap? I remember checking out an orange 240 at whiteheads that they were dropping an SR into.. must have been 2 years ago or so. Was that yours?

Either way, it might take some work to tune the suspension the way you like it, but you won't have to worry about your car not being fun to drive!

[Pyro]

I prefer running heavy springs in the rear and light to stock springs up front.

 

This is a good set up for drag racing and also a good setup for a car that understeers (plows) like an old Z tends to do.

[wheelman]

I've tried running with heavier springs in both positions (front and rear). I've found I can exit a corner faster with lighter springs in the rear but I also have to enter slower. With the heavy springs in the rear the car was pretty loose so I had to be more careful about when I got on the throttle and how much.

 

The nice thing about going to coil overs is you have the ability to experiment with things. I started with the heavier springs on the rear, then after reading the posts on here about different setups I decided to try them on the front.

[johnc]

The nice thing about going to coil overs is you have the ability to experiment with things.

 

Exactly!

 

I guess i'm just afraid of making the wrong choice. I think I'm going to order the front 1" sway bar and the red koni's with groundcontrol coilvers. Spring rates F250 R200. Or do you think I should go slightly stiffer?

 

I haven't had any experience with the Koni reds, but Koni makes a good product. If you're not planning on shortening your struts then be careful about running the car too low. You need at least 2" of bump travel at the shock shaft before the suspension gets into the bump stops.

 

The spring rates you're looking will need more roll control then just a 1" from anti-roll bar. I suggest the full ST kit with 1" front and 3/4" rear bar.

[AkumaNoZeta]

Just for curiosities sake, instead of having it stiffer in the front or stiffer in the rear, what would it be like if you had the same spring rates all the way around?

[jessejames]

This isnt really relevant to your topic, but how long have you been working on the swap? I remember checking out an orange 240 at whiteheads that they were dropping an SR into.. must have been 2 years ago or so. Was that yours?

Either way, it might take some work to tune the suspension the way you like it, but you won't have to worry about your car not being fun to drive!

 

Hi Canadianz , my car was in Greg's shop about 2 months ago. He cleaned up some the wiring for me. I started my swap in fall 2007. I did most of the swap at home with friends. The wiring was beyond me so i had greg finish up what my friends had started.

 

by the way do you have your car out yet? I'm thinking of waiting until may 1st.

 

JohnC

 

How heavy of a spring do i need to skip having the rear sway bar. Is there a thicker front sway bar I can run? I'm afraid I might not have room in the rear for rear sway bar.

[wheelman]

Jesse,

You can use a 280 bar, they are mounted to the subframe in front of the diff and LCAs. I have one in my 240Z and it works fine.

 

BTW: I bought the set from MSA and they are roughly the size JohnC recommends.

[Canadianz]

Hi Canadianz , my car was in Greg's shop about 2 months ago. He cleaned up some the wiring for me. I started my swap in fall 2007. I did most of the swap at home with friends. The wiring was beyond me so i had greg finish up what my friends had started.

 

by the way do you have your car out yet? I'm thinking of waiting until may 1st.

 

Maybe I'm thinking of another car then, I remember seeing one like yours in at whiteheads but it was a couple years ago and had just had the engine cradle installed at that time. We almost went with the sr20 for our 240 but settled on the rb25 instead, so Im curious to see what your car turns out like!

Neither of our cars are on the road yet, both are up on jackstands but should be ready within a couple weeks. Like you, it will probably be around the start of May. Im glad I hadn't put them on the road yet seeing as we're still getting snow!

 

-Rob