RB20 in an '85 300zx??

[Howlermonkey]

Sure we had to put L28s in them to be competitive in SCCA GT racing but we also campaigned S13s with that engine.

The z31 is not a full on race car but more of a comfortable GT car.

Nothing wrong with that niche.

Sure I would prefer to have my 914/6-GT back but I also like comfort which the z31 does deliver.

The Z31 was good enough to score showroom stock championships in 1985, 1987, and 1988 as well as being imsa firehawk champion in 1986.

Not bad for a mushy car.

I'm not forgetting that the S13 made ITA exciting again as I hate seeing a ITA crx win but the mods my buddy Bob Stretch had to do to make it a winner do stretch the rules a bit (spherical bearing rear suspension....etc) but no more than the so called "Tri-link" setup that the ITA RX-7s needed to be competitive or the non-factory disc brakes the Olds Quad 442 required to keep the rear wheels from falling off after a few laps.

Ad hominem attacks against a car type with no data to back them up don't help anybody but a suggestion gleaned from your experiences would go a long way toward helping people here.

Any car can be made to perform as peugeot demonstrated back in the Group B rally days.

[racepar1]

The s-13 is a better chasis in every concievable way and the s-13 isn't even all that great. If you wanna build a z build a 240z, z-32 300z, 350z, or 370z. The s-30 chasis may suck ass by modern standards, but the classic cool factor (and the fact that they are sexy as all hell) make them totally worthwhile to play with. The z-32 is also quite sexy and has a MUCH superior chasis to the z-31 (and somewhat to the s-13 as well). The ONLY problem with the z-32 is that it is pig heavy. The 350 and 370 well...... are just awesome. Any z-car between the s-30 and z-32 should be left in the junkyard to rot as they have nothing to offer. No good looks, no cool factor, and little performance.

[BigVinnie]

Originally Posted by racepar1

Z-31 is trash, tell your "buddy" not to waste time and money with that pathetic chasis.

That chassis has potential if it is swapped out with the s13 rear sub chassis. All it needs is an independant suspension and it's all good.

[Racinjitter]

Originally Posted by racepar1

Z-31 is trash, tell your "buddy" not to waste time and money with that pathetic chasis.

^ is afraid of not having "bolt on" parts. LOL. At least everyone else doesn't race the same car as me.

[Howlermonkey]

I mentioned only showroom stock racing in my post because suspension geometry is as delivered from the factory and the success of the Z31 is about dead even with the S13 with the Z31 having a slight edge.

If you want to compare the Z31 to the S13 in all forms of road racing, the Z31 has more championships and race wins by a huge margin.

Now that you're slagging the S30 to the Z32, then you are out of touch since they have more race victories than any other car save for the porsche 911 series.

I refuse to be hard on the S13 on a S13 site but I spent 20 years working on them and they have all the same problems the Z cars you slagged when racing them in stock form......other than light weight.

Hell......I like the S13 and put my first L28et in one back in 1994 when racepar was 11 years old.

The s30 is the best chassis of any of the nissans in stock form for one reason.

They have less camber and toe change than any of the nissans in the rear suspension.

That's why they still post faster improved touring laptimes than the S13 in spite of having inadequate brakes.

In order to make any of the other nissans perform (s130, z31, s13 and 14, z32...etc), you need to stiffen the rear suspension to the point that rear suspension doesn't move at all.

Any movement induces unacceptable toe and camber change which reduces your rear tire's contact patch and that's why racers limited to stock suspension pickup points and geometry run springs as high as 800 in the rear of these cars.

Any suspension will work if you don't let it.

[racepar1]

Originally Posted by Howlermonkey

I mentioned only showroom stock racing in my post because suspension geometry is as delivered from the factory and the success of the Z31 is about dead even with the S13 with the Z31 having a slight edge.

If you want to compare the Z31 to the S13 in all forms of road racing, the Z31 has more championships and race wins by a huge margin.

Showroom stock racing is the only thing applicable to this argument.

Now that you're slagging the S30 to the Z32, then you are out of touch since they have more race victories than any other car save for the porsche 911 series.

Read my post again. I hardly "slagged" either of those cars. I LOVE s-30's. Their chasis does suck though. It is mushy as all hell and the weight distribution is waaaaayyyyyyy off. Now z-32's just need a vq35 dropped in them, that would get rid of most of their weight problem.

I refuse to be hard on the S13 on a S13 site but I spent 20 years working on them and they have all the same problems the Z cars you slagged when racing them in stock form......other than light weight.

Why? I don't have a problem telling the truth about the s-13 chasis. The front suspension sucks BAD, the rear suspension has an assload too much anti-squat (as does the z-32), and the rear suspension also gains too much toe under compression. The rear suspension can be somewhat fixed by using an s-14 or s-15 rear subframe, they have much less anti-squat and less toe gain, but there isn't much you can do with the front suspension.

Hell......I like the S13 and put my first L28et in one back in 1994 when racepar was 11 years old.

What's your point? Are you supposed to have more racing related experience then me or something? Hell when I was 11 I was travelling all over the southwest with my dad to work on his formula atlantic car at SCCA events. I have seen what cars are competitive and what cars arent. Neither the s-13 or the z-31 were very competitive from what I have seen. To tell you the truth I really didn't see very many s-30's out there winning races either. Now those damn CRX's on the other hand.......

The s30 is the best chassis of any of the nissans in stock form for one reason.

They have less camber and toe change than any of the nissans in the rear suspension.

That's why they still post faster improved touring laptimes than the S13 in spite of having inadequate brakes.

In order to make any of the other nissans perform (s130, z31, s13 and 14, z32...etc), you need to stiffen the rear suspension to the point that rear suspension doesn't move at all.

Any movement induces unacceptable toe and camber change which reduces your rear tire's contact patch and that's why racers limited to stock suspension pickup points and geometry run springs as high as 800 in the rear of these cars.

Any suspension will work if you don't let it.

I disagree with this assessment. I do not see camber change as much of a problem (as long as it is negative camber) and toe change can be worked around (as long as it gains toe-in). From my experience with the s-13 chasis you want softer rear springs, not stiffer. You simply run little static camber and toe to compensate. An s-13 with 800lb rear springs would be borderline un-driveable. I have heard of the datsun 510's, porsche 944's, and the FC rx-7's needing un-godly stiff rear springs (all of which have semi trailing arm rear suspension and gain toe-out and positive camber under compression), but this is the first I have heard of the s-chasis (as it toes in and gains negative camber under compression, which isn't such a problem).

[Howlermonkey]

Originally Posted by racepar1

Showroom stock racing is the only thing applicable to this argument.

Then the Z31 does have the edge in championships and race wins in showroom stock.

Can't change history...........It's already happened.

In improved touring, the roles are reversed but there is a bit of deviation from the stock setup but that's not where your original quip about the Z31 being shit came from.

Your quip applied to the car as delivered from the factory in regard to whether it was a good starting point for a build-up.........hence my mention of the Z31 having more success on the track in stock form.

Originally Posted by racepar1

Why? I don't have a problem telling the truth about the s-13 chasis. The front suspension sucks BAD, the rear suspension has an assload too much anti-squat (as does the z-32), and the rear suspension also gains too much toe under compression. The rear suspension can be somewhat fixed by using an s-14 or s-15 rear subframe, they have much less anti-squat and less toe gain, but there isn't much you can do with the front suspension.

Fitting the S14 rear subframe was illegal in showroom stock and is currently illegal in a S13 raced in Improved Touring.

Originally Posted by racepar1

What's your point? Are you supposed to have more racing related experience then me or something? Hell when I was 11 I was travelling all over the southwest with my dad to work on his formula atlantic car at SCCA events. I have seen what cars are competitive and what cars arent. Neither the s-13 or the z-31 were very competitive from what I have seen. To tell you the truth I really didn't see very many s-30's out there winning races either. Now those damn CRX's on the other hand.......

Well.......now that you opened the subject......yes.

I raced margay panther karts in the mid 70s with a Mccullough MC91 engine when I was 11 and have spent time crewing porsche 935s in the imsa series in the 80s as well as IMSA GTU RX-7s on top of prepping mazda RX2s in the early 80s, RX7s and 240z in the late 80s....etc.

You mention not seeing many S30s out there during the timeframe when you were crewing around with dad.

Here's a link to race results for improved touring cars showing s30s crowding the front of the field.

http://www.wdcr-scca.org/LinkClick.a...1004&tabid=498

The S30 ruled ITS from it's inception until the e30 bmw 325IS and the second generation RX-7 got developed by compaines such as speedsource and the ecu rules were relaxed. Of course spending 100 grand to develop an IT car has been a huge detriment to the spirit of the class but the rich boys want to win at all costs.

If you compare ITA results from the same time frame, you won't find many S13s or CRX because they had not yet been fully developed and you could only race cars 5 years old.....and the ecu rule was not opened up at that time.

FINAL RESULTS FOR - Race # 9- ITA SSB

Contrast that with decade later and you find 240sx, 325IS, integras, and CRX at the front of the field.........but wait..........a S30 still comes in second and you still see them picking up race wins here and there.

I guess you were busy wrenching a Ralt or Van Diemen to watch the races.

http://www.wdcr-scca.org/LinkClick.a...=1051&mid=1908

Not bad for a 39 year old car.

Originally Posted by racepar1

I disagree with this assessment. I do not see camber change as much of a problem and toe change can be worked around (or you can throw a cheater s-14 rear subframe into it). From my experience with the s-13 chasis you want softer rear springs, not stiffer. You simply run little static camber and toe to compensate. An s-13 with 800lb rear springs would be borderline un-driveable. I have heard of the datsun 510's and the FC rx-7's needing un-godly stiff rear springs, but this is the first I have heard of the s-chasis.

I never specified 800 pound springs but said "up to 800 pounds" when mentioning springs in nissan race cars.

Back in the IMSA RS days, 800 pounds (rear) was the ticket on a car as small as a 510 and any 300zx or S130 that wants to be competitive in Improved Touring will need close to that or else the camber change will reduce the contact patch to a small line because of it's trailing arm suspension.

This is especially true with the Z31 as the spring does not act at the end of the arm but rather forward which reduces the spring rate as measured at the wheel.

You do know that current front running hondas in improved touring run as high as 1200 rates in the rear.

ITS Integra - setup help? - IT.com Forums

Why the high rates........because contact patch number one and if you are limited in your class to a suspension that lacks the proper articulation to keep the contact patch as big as possible, then you must make either the spring rate hard to the point of very little movement or keep the springs at a lower rate and limit suspension travel.

Old school was high spring rates and still applies in some cars but many can get away with softer springs now if they limit the travel.

Why nissan went from the superior A-arm rear suspension of the s30 to the trailing arms of the S130 and Z31 is beyond me but it probably has something to do with comfort.

[HyperTek]

wow i thought this thread was about fitting the rb20 into the z31? not which car is better.. Z31 was designed in the early 80s, as expected, it was great for its time.. just underrated today. S13 was designed later mid 80s, so of course there might have been some improvements.

[racepar1]

Originally Posted by Howlermonkey

Then the Z31 does have the edge in championships and race wins in showroom stock.

Can't change history...........It's already happened.

I never disputed that.

In improved touring, the roles are reversed but there is a bit of deviation from the stock setup but that's not where your original quip about the Z31 being shit came from.

Your quip applied to the car as delivered from the factory in regard to whether it was a good starting point for a build-up.........hence my mention of the Z31 having more success on the track in stock form.

Heavy + terrible semi trailing arm rear suspension = crap. No amount of race wins will change that. For an 80's car I'm sure it was alright, hell the few RWD 80's cars that the 300z would have been racing against were predominantly semi trailing arm. I HATE almost all 80's cars, that was a terrible decade for cars.

Fitting the S14 rear subframe was illegal in showroom stock and is currently illegal in a S13 raced in Improved Touring.

I figured that, but there are plenty of people that are more than willing to "creatively" interpret the rulebook. I would guess that the rulebook states something like "modifying the suspension pick-up points is illegal" right? Well if you swap in an s-14 rear subframe you aren't technically modifying the pick-up points on the subframe, so it can be "creatively" interpreted as legal (even though technically it is not just like the other things mentioned about other cars in your previous post). I highly doubt that any tech inspector would notice either.

Well.......now that you opened the subject......yes.

I raced margay panther karts in the mid 70s with a Mccullough MC91 engine when I was 11 and have spent time crewing porsche 935s in the imsa series in the 80s as well as IMSA GTU RX-7s on top of prepping mazda RX2s in the early 80s, RX7s and 240z in the late 80s....etc.

I figured you were an old schooler due to your knowledge of z-31 racing history. My point was not that I have seen more than you, simply that I have been there too. FYI I was not standing around watching while others worked on the car, it was just me and my dad. By the time I was 15 I was responsible for pretty much everything that needed to be done to the car at the track. I don't even think I could count the number of events that I have been to.

You mention not seeing many S30s out there during the timeframe when you were crewing around with dad.

Here's a link to race results for improved touring cars showing s30s crowding the front of the field.

FINAL RESULTS FOR - Race # 8- ITS SSGT T1

The S30 ruled ITS from it's inception until the e30 bmw 325IS and the second generation RX-7 got developed by compaines such as speedsource and the ecu rules were relaxed. Of course spending 100 grand to develop an IT car has been a huge detriment to the spirit of the class but the rich boys want to win at all costs.

If you compare ITA results from the same time frame, you won't find many S13s or CRX because they had not yet been fully developed and you could only race cars 5 years old.....and the ecu rule was not opened up at that time.

FINAL RESULTS FOR - Race # 9- ITA SSB

Contrast that with decade later and you find 240sx, 325IS, integras, and CRX at the front of the field.........but wait..........a S30 still comes in second and you still see them picking up race wins here and there.

I guess you were busy wrenching a Ralt or Van Diemen to watch the races.

http://www.wdcr-scca.org/LinkClick.a...=1051&mid=1908

Not bad for a 39 year old car.

Not bad at all for a 39 year old car. I am not talking about the 70's or 80's though. The s-30 chasis was unquestionably dominant in that timeframe. Manufacturers just weren't producing any really spectacular cars in that time period. But in the 90's, when people started making great cars again, the s-30's age began to show. Still no slouch, but behind the game a bit. BTW van diemens were formula fords or f2000's, not atlantic cars. We started with a ralt rt-5 with an 1800 VW singlecam, then a ralt rt-4 with the 4ag, then a reynard 92h again with the toyota motor. Our rt4 and 92h were most likely the fastest cars of their model in the country, although I admit they weren't being driven by the fastest driver.

I never specified 800 pound springs but said "up to 800 pounds" when mentioning springs in nissan race cars.

Back in the IMSA RS days, 800 pounds (rear) was the ticket on a car as small as a 510 and any 300zx or S130 that wants to be competitive in Improved Touring will need close to that or else the camber change will reduce the contact patch to a small line because of it's trailing arm suspension.

This is especially true with the Z31 as the spring does not act at the end of the arm but rather forward which reduces the spring rate as measured at the wheel.

Totally agreed, but the s-13 does not fall into this category (nor does any other multilink car).

You do know that current front running hondas in improved touring run as high as 1200 rates in the rear.

ITS Integra - setup help? - IT.com Forums

That is really not applicable in our conversation as the 1200lb rear springs are not to increase rear grip, but rather to limit it. That is just what they have to do to get the car to rotate on the throttle.

Why the high rates........because contact patch number one and if you are limited in your class to a suspension that lacks the proper articulation to keep the contact patch as big as possible, then you must make either the spring rate hard to the point of very little movement or keep the springs at a lower rate and limit suspension travel.

Old school was high spring rates and still applies in some cars but many can get away with softer springs now if they limit the travel.

Why nissan went from the superior A-arm rear suspension of the s30 to the trailing arms of the S130 and Z31 is beyond me but it probably has something to do with comfort.

Totally agreed, but agian not applicable to the s-13 or any other multilink rear suspension car for that matter. You obviously know what you are talking about, but a lot of your statements confirm a lot of the reasons why I think the s-130 and z-31 z-cars are useless. That is not to say that you can't work around their issues, but there are much better starting points for the money.

[Howlermonkey]

After doing some research, the S13 suspension, front and rear are a better design than the
S30, s130, and z31.........for performance.

All are more than adequate for street driving but one needs to make the S130 and Z31 rear suspension overly stiff or limit it's movement to combat excessive toe and camber change.

It's been done and the cars do respond........in a racing type situation but you sacrifice the comfort that made the cars popular to begin with.

The S13 front suspension is better in that it enjoys a near zero scrub and again.......it is plentiful in the junkyards of america.

The S13 rear suspension has better articulation and enjoys more adjustability in stock form than the S30, S130, and Z31 but it's not always a gain but fitting this suspension to other nissan models could net one a lot of cutting and welding.

Now the Z32?

It's suspension has superior articulation in both front and rear but I spent many years replacing the upper control arms after on cars that had relatively low mileage because the control arms get hoggeed out from driving in most any conditions that feature bumps and potholes....or dirt roads.
It's also ten times the work to fit that front suspension to another car because of those upper control arms.

Even though the s30, s130 and Z31 dont' have a zero scrub in the front, the Z31 has less than the s30 and s130 mostly because it enjoys a different wheel offset with the S13 being near zero scrub.

One reason to consider newer rear suspension such as the S13, S14, or Z32 is the available differntials.

There are a higher percentage of R200s out there with any sort of LSD in the short nose form than there are in the r200 long nose.

Of course, there is also the R230 found in Z32 turbos and some V8 infiniti cars but the R200 in 4 pinion form has proven strong enough for any but the craziest drag car.

For me, my current project is a M30 which uses S130 style rear suspension with a R200 that is a rare "extra long nose" in that it has a sensor for the abs in the nose which makes it near an inch longer.

If I go through all the hassle of making a one-piece driveshaft for that car and the diff fails, I may not find another easily meaning fitting a long nose and getting the driveshaft shortened.

Fitting the S13 rear setup would get me differential dimensions that are more common and the mentioned availability of LSD is more common.........plus you get a bit more adjustability and toe/camber control in stock form meaning softer springs can be used while still getting good performance.

Even though I took offense to racepar's quip about the Z31, this thread did prompt some research that will help me in the end so I am cool with Racepar and thank him for getting me moving on this.

Back to discussing RB engines in the Z31.......

The Z31 and any left hand drive nissan were never intended to use that engine so no consideration was made for fitment so...........you usually find steering shaft or the rack itself in the way when fitting different engines as well as needing crossmember mods to make everything fit.......and usually a custom elbow/downpipe or downpipes in a turbo application.

The N/A crossmember of the Z31 seems to be a better starting point because it's pads are not skewed like the turbo crossmember but maybe you could use the clearance afforded by the skewed mount pads on the turbo crossmember.

The RB setup is best fit as a engine/transmission unit together because the Z31 stock setup has the tranny bellhousing between 6 and 7.5 inches hanging into the engine bay while an inline engine like the RB cannot sit that far forward because it just won't fit that way.

For some reason nissan also had hung the VG30DE and DETT way out front about the same amount even though they don't have the intrusive crossover pipe.

Racinjitter's setup is a good template to follow and he did a good write-up which is more than adequate to help someone else do the same.

One thing when considering these swaps is shifter location. The availibility of RB versions of the FS5R30 tranmissions is low in the US and there are at least 3 different shifter locations in that tranny found in US market cars.

Pathfinder v6 two wheel drive is the shortest at 27 inches from bellhousing to center of shifter shaft but you can find them for 150 bucks at a u-pull junkyard.

The Z31 version of the FS5R30 tranny, if I'm not mistaken, has a bit more distance from bellhousing to shifter shaft while the Z32 is far and away a lot longer in that it has the shifter actually hanging behind the tranny on a sub assembly.

Which is best for you, is up to the engine choice but I don't know the measurement of the RB tranny from bellhousing to shifter..........it might be the same as the pathfinder somewhere between the Z31 implementation and the pathfinder........which would make it 4 different lengths for the same tranny......I just don't have that measurement.

For my application, 29 or 30 inches distance would be ideal and I'll guess the RB application of that tranny would fit better.

If you make over 400hp, the FS5R30 is almost a must.

The bellhousings can be swapped from application from application but it's a bit involved and that tranny was never intended for any L series engine.

You can see what's involved in Austin Hoke's Z32 to L engine adapter thread or the thread for the mazworks adapter at hybridz because his adapter for the L series requires the bellhousing to be removed for machining.

http://forums.hybridz.org/showthread.php?t=113143


Then you have tailshaft length differences with the pathfinder being the shortest but that dimension only impacts driveshaft length and you would already be having one made a custom length anyway.

There you go hypertek.

[Mac Attack]

Looking at putting together an ITS 84 300ZX as inexpensively as possible. Anyone have any info? Thanks.