Opened my seven up really for the 1st time today on the Interstate. Dropped to 4th and it went from 65 to 90 pretty fast. Shifted to 5th and got only another 10mph. Total of 100mph before it dropped off acceleration and seemed like it wasn't gonna get much more. Is this normal for N/A 12a's? I have headers and free exhaust too.

 

really? i have a gslse with just a 45dcoe on it, and ive been up to 120 in my car, in 5th gear at like 6k

 

I think 130 was my top before the car just didnt want to go any faster, of course in a car built in 1984 I cant really say I wanted to go much faster either

 

alright, this is JUST for the n/a 12a's guys then.....

 

No not normal. What RPM's did you reach in 5th? Whats the mechanical condition of the car? Compression? Fuel pump and filter? Ignition system?

 

mine stutters and dosen't do anything at 80 mph....i've gotta figure out what's wrong because i have a weber 45dcoe (with a Holley red fuel pump feeding it), RB header and presilincer. I think it's either choking itself out or leaning out....i don't know. If you guys have any thoughts please let me know!

 

yea.. i too am topping out about 105.. i was on the way home the other day and the straight away on the highway was empty so i opened her up.. 4th got me to 105, but the rpm's weren't going any higher.. about 6800rpms... i think my timing is too advanced though.. and my front brakes might have too much drag to em..

this summer will fix her though.. se suspension is going on and my carb will get Sterling treatment.. as soon as i catch all these bills up... it sucks being broke..

 

wow, that was quick

 

I have been up to 110 in my 82 and then I ran out of road. I probably could have hit 120 or so.

 

new OEM cap, rotor button, NGK wires, new Nippo plugs. Timing has not been set w/a light, just by ear...

compression is the factor I am guessing on since the engine has so many miles. But, it starts instantly and runs really strong picking up speed all the way up to 100mph. Maybe I'm not being patient enough for the 100hp rotary. I mean, the small hp. amount of these engines can only push the car so fast.

I was only like 5000rpm at 100mph, but it really wasn't gaining rpm's or mph after that point. Either it's being held back by something (fire, fuel, air) or it just doesn't have the power to go on past that.

What's normal for a 12a that's hasn't been rebuilt-ever?

 

I've reached 120 mph on the dial in my 85 GSL, when it was bone stock. Of course with 215/50-13 tires, I was actually going about 7% slower so that would be 112 mph.

 

when my gsl was bone stock i got 115 easily and it should definetly be more wit the exhuast

 

i do km/hr in Canada eh and ive been to 195-200 i felt like i much more left stock everything running a bit rich with no muffler haha

 

I went out for a 3am drive the other night and hit 115 on the speedo. It was stupid but the speedo was still climbing when I let off.

I have a 1980 with RB full exhaust and an electric fan.

Before the RB exhaust, I chickened out 115 again.

115 in the RX-7 is a different experience. I've done 130+ in my maxima and the experience isn't even the same. 115 in the RX-7 just seems so much faster.

BTW, keep it in 4th longer.

 

So you were doing around 112mph then.

Well, I suppose with more time and more road I could probably get 110 or so out of it. Don't see 120+ happening though.

Only thing else to try is new fuel filter and reset the timing. Maybe the timing advance is not kicking in right?

Hey, how much more could I get out of a sterling?????

 

will do. I could probably get a 100mph just in 4th. 5th must be a really, really low gear...

I know what you mean about the diff. My Infiniti J30 will do 140 easy(would do more but I haven't really pushed it) Anyways, 140 in the J30 seemed like 80 in the Rx-7. I'm guessing b/c you are lower to the ground it seems that way. Things started shaking a bit at a 100 in the seven too.

 

Top speed at Laguna Seca in a one-year-old SS '81 was only 103. Anyone going over 110 with a stock 12A is on a long downhill. Speedometers are notoriously inaccurate.

 

Be careful. Above 90 with a stock body/suspension they like to fly. Bad aero lift= less and less control. I think your running out of fuel if you have a free flowing header exhaust. You probably have a restriction in the fuel system or not a strong enough fuel pump. Or your air filter is restricting you.

 

I beg to differ. I have compared my speedometer with police devices that tell how fast you are going and after doing the conversion considering the different wheel size it comes out accurate. And the 112 mph was on a totally flat, long piece of land on I-60 by the VLA in NM.

 

Carl: I can definitely feel the lift... However, I am still pleased with the handling from such a light car w/no aero kit. 80 is where I will keep it most of the time. Have you top ended a 12a w/a sterling yet??

cdrad51: I think the speedo is quite accurate myself. With 185/70/13 tires, you should be very accurate up to around 80 or so. But, if you are off even a little bit, by the time you are doing a 100 you are off even more from actual. Faster you go the less accurate I think it would be. I think I'm within 5mph of the truth anyway...

 

When I first got my seven. I was terrified of going over 70 because it felt like the front end was just floating. I changed out the springs for a set of eibach prokit and the feeling went away. I've only been able to go up to about 100 and it gets there pretty quick. I usually don't have enough road or time to see if I can go past that. Actually now that I think about it, I think I've hit about 105 on a long stretch once but even with the springs installed I don't feel comfy going that fast.

 

Carl: One more thing. I am using a cheap Fram paper air filter too. I'm sure that is restricting me alot at top end. Maybe my idle mixture is low too. Didn't you say somewhere you go 2.5 turns back from choking the engine?

 

I once got pulled over and the cop said he clocked me at 104, and that was after I let off for a few seconds in 4th, which said I was doing 90, so I dont know how accurate the spedo's are, but in 5th Ive gotten it up around 110, but I had to replace my fuel filter, before that I couldnt break 85

 

interesting......of to AutoZone I go!

 

I was on SoCal cruise this weekend doing a 100. 2 FD's past me about 120. I wanted to play, but my car felt to unstable. I'm cosidering an airdam now. I know my car can go faster with better aerodynamics.