ok i'm looking around for another rx-7 and was only looking for TIIs for a while. However, I'm curious as to what the difference between a stock TII (series 4) and a lightly modded series 5 NA. If the NA has headers and/or exhaust with an intake would it be comparably quick? I owned an '89 TII with intake and boost controller and i know neither will be as quick as that, but a series 5 NA sounds pretty appealing if it will be as quick as series 4 TII.

thanks, alexi

 

I'd be willing to bet a 87 TII with intake and a mbc would be just as fast as your series 5 t2. The s5 runs 2 pounds more boost stock than the s4 t2, and that's where the majority of the power increase is coming from. I've seen some s5 n/a's with full exhuast hitting consistent low 15's, so I'm sure it would be a good race for a t2 and could even edge them out. However if you want to go fast I implore you to go with the t2. I was hitting 103 traps with just my thunderfab dp/mp and a TID (walbro 255, and fcd for fuel).

 

It's going to be a big difference between a stock S4 TII and a lightly modded S5 n/a. Even *if* peak power is the same, the TII will have more grunt further down.

 

A better comparision would be against a light Series 4 NA and a series 4 T2.

For example a 86-87 Sport stock was only less than a second slower than the 87 T2, (7.6 seconds vs 6.8 seconds) and within 7 MPH top speed (135 vs 142).

To get another 20 Hp on a Series 4 car should be pretty straight forward and put you into series 4 T2 power range. Heck just refiting a S5 NA intake, a better air filter and a decent exhaust to a series 4 NA will get you that 20 HP.

As opposed to the considerably heavier NA S5 cars, that only had another 2 Ft/lbs of torque over a S4 NA.

 

I definetly agree with the S4 NA v. S4 t2 example. With the NA motor, me and my friends T2 were door to door even through all gears until 3rd when I would nudge ahead. My car is pretty light, no options at all, with removed 6 ports, emissions, TB mod, full exhaust etc etc.

 

The manifolds on the s5 help too. However a mbc and intake on a s4 tii will be faster (due to weight) than a s5 tii with the same mods, just my opinion. The s5 tii has 20bhp over the s4, and only runs .2 faster in the 1/4. Most of that is just acceleration due to a better low end.

 

thanks all; i think i'd be more inclined to stay with a series 5 NA because of the little updates (lights, interior, wheels, etc.), but i had no idea they make it weigh that much more does anyone know the 0-60 time of a stock series 5 NA vs. series 4?

alexi

 

what model???

for example a 88 GXL typically (most road tests) did the 0-60 in 8.1 seconds a the 1/4 in 16.2

But the 89 GXL (even with the extra 150+ lbs and 16 more HP) did a 0-60 in 7.8, with a 1/4 in exactly the same 16.2

while the 86-87 Sport typically did a 0-60 in 7.6 vs the 7.6 for a 89-90 GTU with both doing the quarter in 16.0 @ 87.5

However the 89-90 GTUs did do typically a 7.4 0-60 with a 15.8 quarter @88, so it was the fastest 0-60 and 0-100 NA, but again not by much. As a referance, the S4 T2 best road test recorded 1/4 mile was 15.1 @ 91 MPH.

So, VS the NA in both series... would you rather have a slighty heavier car or a slightly lighter car, with almost the same 0-60, 0-100, and 1/4 miles.

 

To make it easy, if you wanted a TII...don't settle for an NA. Plain and simple. NAs are good for beating the regular ricers and to auto-X and the such, but not for big boys like LS1s, VR4s, 300ZX TTs, anything in the 14s or lower really. If you have dreams of running deep in the 14s or lower I'd definitely stick to getting a TII, no matter how long it takes to find one.

 

I ran a 14.1 @99 with just intake, full rb exhaust, and superchip. No NA could ever do that.

 

Definitely go with the T2 if the car isnt trash. Boost is addictive and I have to hurt myself physically when I start thinking about upping the boost past 12 lbs in my Supra without any more supporting mods. (ie true 3 inch turbo back exhaust or a better FMIC)

Turbos = best bang for the buck. Just be careful.

 

C&D 4/86 lists the S4 TII @ 6.5s, 1/4 in 14.9 @ 94MPH. Check out the article on www.iluvmyrx7.com. Recall the n/a S4 vs S5 had a delta of 14 HP, 2 ftlbs. In other words the power was made further up. I'm willing to bet if you modify a n/a intake/exhaust/porting to get 20hp, you will gain it mostly higher up in the rev range. In other words you won't be effecting your full curve the same. My point is if your only measure is the 1/4 mile then fine, but having a wider range of usable power is nice.

 

If you actually read that article, you would see that the car tested was really a 87 Sport with the T2 motor and driveline.

The car did not have power windows, sunroof, or a tilt wheel, or even power mirrors. It was a special one off test bed to judge North American reaction to the turbo and not indictive of the fully loaded T2's that actually came to America. I personally wished they had brought the GT (as called in that article) to america, as I would have bought it instead of the Sport I did, back in '87, because I sure was not goint to buy the bloated heavily power optioned T2 they did bring over.







And I would be happy to post the NA 0-100 times if you would like a wider range.
*edit
In addition if you look at the torque curves the S4 NA cars actually had a lower peak curve (138ft/lbs@3500 instead of the S5 NA with its 140Ft/lbs@4000). This made the S5 more even through its upper torque range and made it better to rev higher, which it needed to produce power with the lighter rotors. Yes it also made the torque curve much flatter from 4000 to around 6500 RPM, but at the cost of lower torque when starting off.

They basicly just made the motor rev more.

 

It's been a while, I was going from memory and flipped to the final page.

I still say the times stand, they say 100lbs is 0.09 in the 1/4. It's hard to say power windows, power mirrors, sunroof, tilt steer make a full 100lbs. I'm having trouble seeing in that picture, but that GT looks like it may have AC. I was mearly trying to point out that the best case TII scenerio, just like you were pointing best case n/a scenerio. I'm not trying to undermine what you've said. With all the stuff removed from my TII, it's light too. (I haven't gutted it)

I'm aware of your edit comments, I was suggesting the same. Comparo, we can just post this (also considering the stuff you mentioned before):

 

I have always liked that article you posted a page from... But much like them, The last two paragraphs in that article sum up my feelings about weighty blvd cruiser versions of the FC turbo that we got.

And boy did they test a dog for the 88 GTU or what?

 

Just curious, which aspect bugs you more about the TII, not enough additional power or the GXL style treatment? I'll agree that the S4's turbo isn't very good and few here would argue against less being more.

Just noticed, the C&D GT has PS.

Weight wise, my car didn't come with PS or ABS. I *think* the turbo is suppose to weight 45lbs more. On my car that's offset by the lighter rims (~10lbs/corner). There's also no AC, single exhaust, radio & extra OEM amps => aftermarket, rear wiper, cold start assist. The GTU should have ~20-30lbs on mine. Again, I'm just trying to point out the better cases, especially from today's perspective.

 

S5 N/A = slow

 

Actually refering back to the post you made, the T2 is 200lbs heavier than even the 88 GTU which was only 60lbs lighter than the GTUs. But that is typical. The T2 added a lot of weight just in the heavy duty driveline. A lot more than 45lbs.

I just don't like the power everything versions. As I mentioned earlier If they had brought the GT here instead of the GXL in Turbo form I would have bought a GT instead of the Sport that I did back in 87. It would have been as pure as the Sport.

Instead they brought the bloated high dollar Turbo II. Sure it had good HP, but it also had rear wiper, and power mirrors, and power this and power that. Heck I think the AE even had headlight washers.

I come from the purist world, where I don't care if I have to reach across the car to roll down a window. Even my 'vert, if they made manual windows regulators for it, I'd retrofit them in.

Now I still believe in A/C and PS, those help the driver, but a tilt wheel; power mirrors, rear wipers, headlight washers, power windows... those are all extras are just fluff in my book.

My old school says, mechanically simple as possible, light weight (did you know that the 10AE was within 50lbs of the weight of the Non-P package manual tranny 88 'vert?) and great balance.

 

I agree with pretty much everything you've said. I don't want power windows, mirrors. I don't like cruise, I removed it too. @ 6'5" I appreciate the tilt steer. PS is for trucks and wiennies. (I do pine for the quicker PS steering ratio)

From the Brian Long book "...[the 13BT] was only 18kg (39.6lbs) heavier than it's 146bhp counterpart." Can you confirm the trany and diff are indeed substantially heavier? I've asked that before and received no answer. Numbers?

IMO the TII should have atleast had the option to be sold stripped of the crap. The turbo should have been better and had contemporary turbo efficency, like the S5. The IC should have been increased enough to center the hood scoop. Stiffer springs & shocks. 225 tires all 'round /w 7.5/8" rims, but style/weight like the S5s. Quicker steering on the manual rack. Same colored external door trim ala S5.

 

yes the engine was only about 40 lbs heavier, but the driveline was the big difference. I had heard 120lbs, but I don't have anything to back it up other than my own conversion on my 'vert and that article that I posted (which claimed their stripped GT weighed 2830- about 180 lbs heavier than my 87 Sport in stock trim according to the window sticker). I know the sunroof alone adds 40 lbs to the structure, as do the S4 T2 wheels, so 100-120 lbs sounds pretty close.

The other thing to remember was that the Base and Sports got reduced insulation and lighter (read thinner) carpeting, again the didn't even have the tilt wheel or cruise and in some cases even a cassette on the stereo.