Street Tires Suck

[SilentNight1647]

.595 lift intake/exhaust 306 adv. duration 274@ .50 and yes I did port match the throttle body to the intake and no it wasn't any fun in retrospec I should have gone with a smaller one but oh well.

[vrocious]

this is the tyre i'm talking about

http://www.federaltyres.com/ss595rs

i thought they were an american made tyre (although if it was american they would be called tires wouldnt they ) but turns out like many others they are asian. anyhoo i found a distributer in the states, surely there is more, http://www.customwheelsdirect.com/tires_brand/Federal.php

hope it helps ya!

[JMortensen]

I think that people make much more out of the semi-trailing arm theoretical limitations. Porsche was running semi-trailing suspension until the 90’s and 280zx,s won enough races as well to show that the real life difference is not always as significant than suggested by theory. According to theory current 911 should also have grossly sub-par handling with a rear mount engine, But then they dominate.

Porsches are also known for putting doctors into trees, due to their twitchiness. Having been to a track day and watched a 911 loop in front of me when they lifted off the throttle at 100+ I might have a slightly different perspective on the issue. By the way, I'll bet that most/all of those sucessful Porsche race cars have insanely stiff suspensions to minimize the toe and camber changes.

Here are Bernard’s numbers with a 280zxt with stock pathetically soft and worn suspension:

60ft: 1.6909

330ft: 4.9192

1/8 mi: 7.5660@93.21

1/4 mi: 11.7589@117.55mph

This was with slicks, time was I believe in low 12’s on street tires.

 

Point being, while the suspension design is not “optimal”, it’s certainly not the limiting factor at this point in the game.

This is absolutely true. The suspension is not the limiting factor at this point. I can't speak for John, but I was simply pointing out that the toe and camber changes pretty dramatically with bump travel, so I would definitely not go to soft springs in the back to improve traction.

[Afshin]

I like your answer Jon

Fortunately, I have not been put into any trees, as of yet. Mercedes cars, 280zx, 510 and others were plenty stable with semi-trailing and front mounted engines. Current 911 GT3 with rear engine and non-trailing suspension are also plenty stable. What I believe made the earlier Porsches so unforgiving was the combination of semi-trailing along with rear engine.

Mind you I would rather have a multi-link suspension set-up. However, my personal view is that the real life disadvantage of the semi-trailing set ups are often grossly exaggerated. This is based not only on professional racing successes with such set ups, but also based on my personal non-professional experiences with a first generation Z, 280ZXT, 300ZX, 3rd and fourth generation supra turbos and a 3 series BMW which I have owned and pushed to their limits (the supra twin turbo was actually not mine but I drove it for 3 months straight).

Fact remains that my 280zxt with proper front and rear alignment (with helpful tips from yourself), proper bushings, comfortable eibach springs and tokicos has outhandled and/or matched STI’s and other “better†designed machines at several tracks.

Stiff rear control arm bushings and some rear toe in practically speaking resolve the off- throttle instability from the associated toe “out†change. And the camber gain with compression can really help with keeping the rear planted and to some is enough of a benefit to more than offset the camber loss during extension (still a debatable issue). It really takes very little to get them to perform admirably.

I fully agree about softer suspension not helping.

[SilentNight1647]

Well I dialed up the boost with a Home Depot (or in this case Ace Hardware) boost controller and it got interesting with it barely turned in the car hits 10lbs of boost with a quickness and will break loose even when I start in second gear from a dead stop once it spools at about 2500. I blew a boost tube off the intercooler though due to a loose hose clamp. I think all it needed was a little more boost to wake it up, I ended up taking the homeade boost controller off and just using the wastegate because I don't know if the motor will hold up too long with boost at those levels. Also does anyone know what the numbers M070R mean on the compressor side of the turbo? I thought it was a part number but no one seems to list it the only part that makes sense is to me is the 70R. I got the turbo from a less than reputable source about 2 years ago and never bothered to look up the numbers to see if what he gave me was what he said it was and now I wish I had.

[Afshin]

Yup, going from 5 to 10 psi certainly makes a huge difference.

Question, are you certain that your compression is really as high as 10:1?

Also do you have a wideband O2 sensor?

[SilentNight1647]

I'm fairly certain it has KA flat tops that were milled and it definetly has a milled P90 on it. With a whistle it checks out between 9.5 and 10.5 granted the whistle is really old and beat up but I figure at least 9:1. I need to talk to my machine shop (read:my Dad) and figure out if he used the pistons I bought or replaced them and didn't tell me. And all I've got is a narrow band that sits in the car I really need to go to a wide band though. Oh I figured out what the M070R stood for upon closer inspection it says MOTOR with Nissan stamp in front of that so I guess it is a OEM Nissan T3 which doesn't really surprise me considering who I got it from. I am just going to dial the boost up to 10 and wait for something bad to happen and rebuild it from their.

[Guest Gr8White]

car has alot more in it I was trapping at about 95-98mph all day running high 14s low 15s so if I can get traction I think I can see 12s in it.

 

Have you had the car dynoed? What is the weight with you in it? The MPH is a bit low and 95- 98 mph would be more typical with a mid 14/ high 13 second car. The MPH will tell you everything, assuming that you have no clutch slippage issues. What is the RWHP and weight of the car? Traction or not, power and weight are going to be the determining factor in what the car is capable of.

[Pyro]

A rear squat looks very similar to a front lift. However, front lift is what you want because all the wieght is moved on the rear springs. Rear springs that collapse can't hold the weight of the car and therefore don't tranfer the weight. The trick is to run strong rear springs and struts and soft front springs and struts. Not good for handling, but good for weight transfer. Also, pull off the front sway bar.

 

Yes, 95 to 98 mph is not fast enough for a 12's. That speed indicates 15.0 to 14.4 et in a street car. A car setup for pure drag racer (high stall, high gears, slicks, posi, and heavily modified suspension) could manage a mid 13 with that mph, but not a street car. A stock 350z runs 14.0 at 100 mph, for an example of a street car that runs 100 mph trap speed.

 

Years ago when I first took my V8 Z to the track it ran a 12.9 at 110 mph. Even ran a few 14.5's at 110 mph with a lot of wheel spin. Wheel spin slows the et but not the mph. Mph is Mph, and 98 mph indicates 220hp in a 3000 pound car.

[Afshin]

The L series engines are pretty tuff, failure is usually not due to the engine components but due to poor fuel and ignitiion management with associated detonation.

Point being if you blow the engine and rebuild it you will have made no progress. You already put more than most into the engine and not nearly enough into the EFI system. The stock EFI is really not adequate for performance cams and high compression mods. Instead of planning for another rebuild, my advice is plan for an updated EFI such as MS. You can get the system pre-assembled for cheap. Believe me, it will improve your performance much more at his juncture than any further engine work. Stock EFi and injectors are way too limited!!!

[SilentNight1647]

I need to go to MS one of these days I did ask my Dad and the pistons in that motor are dish pistons so the 8-8.5 is the new approx measurement until I can get it whistled with again hopefully with a different one. On the plus side it doesn't detonate at all on 93 but it was weird today when I drove home it would only spool 3lbs of boost w/o my homemade controller on it. I don't know the weight of the car but I weigh 200lbs and the car has full interior and manual everything.

[Guest Gr8White]

I guess it really depends on your definition of "street car". Regardless of the suspension, if the car hooks and you drive it like you stole it, it can run the number. It's really as simple as that.

 

A case in point was/is my 1988 Mustang GT. Back then, my car was stock with the exception of 3.55 gears, Flowmaster mufflers and a K & N filter. On stock Goodyear gatorbacks, the car refused to run faster than a 14.30 @ 97 mph with 60's in the 2.00 range, spinning. Swapping out with 26 x 8.5 M/Ts would result in 1.8 60' times and consistent ET's in the 13.80 range @ 97-98 mph. The car would dead hook with a 5000 rpm clutch drop and I powershifted every gear. You must hook up and do everything right, but 13's @ 98 mph are doable with traction and driving skills. I soon found that my T-5 was the limiting factor, seeing that I had to drive it home!!! ET or towtruck, Hmmmm. When you are poor and still in school it's a fairly easy decision to make. If I didn't powershift, 14.0's were the norm.

 

It's been my experience that 103 mph is about the cut-off for a 12 second timeslip. I'm sure there are some that have done this with less mph, but I haven't seen any cars that I can remember hit a 12 with less mph....

[Pyro]

I guess it really depends on your definition of "street car". Regardless of the suspension, if the car hooks and you drive it like you stole it, it can run the number. It's really as simple as that.

 

A case in point was/is my 1988 Mustang GT. Back then, my car was stock with the exception of 3.55 gears, Flowmaster mufflers and a K & N filter. On stock Goodyear gatorbacks, the car refused to run faster than a 14.30 @ 97 mph with 60's in the 2.00 range, spinning. Swapping out with 26 x 8.5 M/Ts would result in 1.8 60' times and consistent ET's in the 13.80 range @ 97-98 mph. The car would dead hook with a 5000 rpm clutch drop and I powershifted every gear. You must hook up and do everything right, but 13's @ 98 mph are doable with traction and driving skills. I soon found that my T-5 was the limiting factor, seeing that I had to drive it home!!! ET or towtruck, Hmmmm. When you are poor and still in school it's a fairly easy decision to make. If I didn't powershift, 14.0's were the norm.

 

It's been my experience that 103 mph is about the cut-off for a 12 second timeslip. I'm sure there are some that have done this with less mph, but I haven't seen any cars that I can remember hit a 12 with less mph....

 

 

 

Well those mustangs pull up the front tires up so easily they would almost be considered a drag car. hahahaha. Z's don't like to pull the front wheels off the ground. After tweeking my Z it ran 1.5 second 60 footers and still didn't pull the front tires off the ground.

 

I have seen some VW's bug run 12's with less trap speed but that is because the engine were on the rev limiter and wouldn't trap any higher. I have also seen a few top fuel car run 12's at 60 mph after shutting down after 1 second. hahaha. So, I guess there are always exceptions to the rule. But a z needs extra work to get it to hook since it was made to be a road racer not a drag car.

[Guest Gr8White]

Well those mustangs pull up the front tires up so easily they would almost be considered a drag car. hahahaha. Z's don't like to pull the front wheels off the ground. After tweeking my Z it ran 1.5 second 60 footers and still didn't pull the front tires off the ground.

 

I have seen some VW's bug run 12's with less trap speed but that is because the engine were on the rev limiter and wouldn't trap any higher. I have also seen a few top fuel car run 12's at 60 mph after shutting down after 1 second. hahaha. So, I guess there are always exceptions to the rule. But a z needs extra work to get it to hook since it was made to be a road racer not a drag car.

 

I think pulling the wheels is way overrated. You are wasting energy at any point past what it takes to get the tires fully planted. I used to think that was the name of the game and have nearly drug the bumper off my GT with big wheelstands. I have found that tuning the suspension down to lift both tires approximately 6" is much more effective (not to mention saving your oil pan and LT headers). My car 60's better, stays in the groove and keeps the tires loaded to the ground....Let someone else pull the big wheelies and woooo the crowd, I'll take the win light!!! The best thing I ever put in my car was a rear anti-roll bar....

 

The big wheelie folks are usually the ones doing dry hops too, a total waste of heat in your tires. If your suspension will not allow you to adjust the wheelstand out (Ladder bar, etc.) fine, but to intentionally put the car on the bumper for a show is ignorant, not to mention unsafe!!

[Pyro]

Never said putting the bumper on the ground was a good idea. Just said mustangs hook up very easily. Doesn't take much power to get a mustang into the 13's. Yes, they can be hard to manage once power levels increase. On the other hand, a Z and most other 2wd street cars have a hard time hooking up and typically deliver slow et versus mph.

[Guest Gr8White]

Never said putting the bumper on the ground was a good idea. Just said mustangs hook up very easily. Doesn't take much power to get a mustang into the 13's. Yes, they can be hard to manage once power levels increase. On the other hand, a Z and most other 2wd street cars have a hard time hooking up and typically deliver slow et versus mph.

 

Sorry Pyro,

My statement about putting it on the bumper was more of a generalized rambling than being critical about anything you said....I'm nowhere near to the point of getting my Z to the track but I get the feeling it's going to be more of a handful than my Mustang ever is or will be!

 

I'm going solid axle all the way, call me old school but that IRS scares the crap out of me.

[Pyro]

No need to say sorry. I wasn't upset with your comments. I guess I should start uses those silly faces to help describe comments.

 

Yes, a straight axle is the way to go. Now that I'm married with a 2 year old and another one due next month, I'm much more concerned about breaking stock datsun axles then when I was single. I would hate to make my wife into a single mother.