N/A 12a streetport time slips
 

On average what do you guys run with a n/a streetported 12a and what setup do you have? :bigthumb:

CDRAD51 would be a good guy to PM. He would know 0-60 times on his sterling carb, RB SP 12A with the chrome header (not the SP header) and I think the regular exhaust back (also not SP). Cant remember his best time though.

Not sure on my setup as I havent gotten around to get my car running right again. I have stock nikki on RB SP with the SP exhaust. Other mods in my sig. Hopefully sometime soon I will have money saved up for a sterling/carl carb.

Best time I did on 0-60 was 8.1, measured with a GTech. Wasn't fully done with fine tuning the carb though, but the rear rotor has a spun bearing and the engine is being repaired right now. I should be able to take it to the 7 secs range with this setup in my estimation.

Haven't done any 1/4 mile runs.

i haven't done 1/4 mile either, but i'm sure there's a formula to convert 1/8 mile times to 1/4 mile. mine is a '74 model sp 13b with rb holley setup(600fm). with only 2 run, my quickest time is 9.381 @76.225 mph in an 8th mile.

My 1/4 mile times are in the range 14.7-14.9 seconds on 92oct fuel.

Stock port 12A, highly modified Nikki carb as Sterling recommends, efficient header and exhaust/muffler system[just legal], K&N air filter, improved ignition wiring, deleted air pump and air condition, running on Dunlop Formula tires-205 14s with Enkei alloy wheels. Mods not effecting time include stronger clutch, lowered suspension, KYB shocks, King springs, stiffer sway bar, and poly bushes.

Estimate 152hp at flywheel.

Holy shit. My car must be a lot faster than I thought. I figured my car would be high fourteens, but you have a stock port 12A running those times!

Do you have weight reductions other than the A/C and air pump?

Clean85- The engine is the 85 12A which I am told was a slight improvement on earlier engines. Rumour has it they came with lighter rotors and better porting on the rhd export market derived from the Japanese home market . The UK 'Autorcar' recorded a 16.1 second quarter mile, while an Australian mag said it produced an extra 10hp. Thus, my stock might be better than yours! The only mod I forget to list was an upgraded fuel pump.

I have tried to maximise performance of the stock 12A with just bolt-ons and the original carb. The reason the clutch was upgraded was it was a no cost mod when the original was burnt out. The car was stolen from my beach house and driven up sand hills by a bunch of drunk kids celebrating their graduation.

The 13B 4port is a great engine, I really enjoyed Jeff 20Bs write up of what he is doing. I seriously looked at a set-up like yours for my next project

This gives me hope as well, I have an 1985 RX-7 GSL and my goal to get into the 13's with a weber carbed street ported 12A.

Not that I don't believe you, but do you have time slips for those times?

Cdrad: Yes.

However, in all fairness to North American drivers the car is a 1985 rhd model. When I first posted my times some 3 years ago, several sources pointed out these export vehicles had several Japanese improvements being more powerful due to improved porting and a more free flowing exhaust system.

As I said earlier in this thread, both UK and Australian magazines quote an increase of 10-12hp over earlier RX-7s, while the Autocar road test gave a 1/4 time of 16.1 seconds which is substantially quicker than road tests of 12A US vehicles and only marginally slower than the 13B GSL-SE. However, I think it may be possible all 85 12A engines came with the lighter improved rotors.

The 12AT model with 138hp achieved a 15.2-3 second 1/4, so any fully optimised 1984-85 12A with bolt-on modifications getting 155+flywheel hp can easily achieve sub 15 second ETs. I know of 14.5 seconds using a track only exhaust system.

The main improvement to stock equipment is to the Nikki carb, read the Yaw and Stirling websites for details of modifications and the resulting performance
as to what can be obtained. Another of course to consult is Pineapple Racing who came up with the design of my exhaust/muffler system.

cdrad- Looked at an earlier post fron you, there are some great mods on your 7 and I note you have a Sterling carb.

However, a 0-60 time of 8.1 seconds is way down on your potental. I estimate your 1/4 time would only be around 16.3- 16.5. seconds This is what you would achieve on a 110hp engine yet if tuned with the set-up you have there should be 140+hp at the flywheel.

Once your engine is repaired you say you are going for a 7 second time. I suggest you should as a start be aiming for a 6.7second 0-60 15.2second quarter mile. Then with much fine tuning, 6.5 which may just break the 15 second mark for the 1/4 mile.

The time for the 13B RX-3 is interesting but irrelevant for RX-7 time comparisons.

the 85 rhd model just had better exhaust like most cars in Japan do

On my old street ported 12a series 2 i ran a 14.8 on shitty tyres just before i sold it. But that was an ordinary rx with a brand new engine, with better suspension and tryes i would have expected low 14's

On my old street ported 12a series 2 i ran a 14.8 on shitty tyres just before i sold it. But that was an ordinary rx with a brand new engine, with better suspension and tryes i would have expected low 14's

bullocks My best time is 14.69 with a 1.8 60ft. And I dyno'd at 140rwhp. Which is about 175 flywheel. no way a 150 fwhp car can run mid 14's.... I had one and the best time i ever got out of my 12a was a 15.7...

the best I ever got was a 15.3 on streetported 12A with weber IDA and open exhaust. Think it would have been better if my clutch didnt start slipping about 3/4 of the way down the track and i had to let off a bit.

Hyper4performance- The 84 GT-X with only 138hpflywheel had an offical 1/4 time of 15.2seconds and good drivers were marginally quicker. A well set 12A streetport with 125rwhp can beat 15 seconds. I have no idea why your times were slower.

In reality, why argue over minor differences of data from different sources measured at different times. Just enjoy your Rex. However, if I had wanted real performance in my street car I would have bought a 10.5 second package with 500rwhp, then if it did not perform after spending megabucks I would complain to the tuner.

Hyper,

What's the elevation level in Seattle? I don't remember the numbers on elevation effect but it definitely has an effect. Perhaps that could be a source of discrepancy?

almost 0


how come ur running 92????

Elysian:- I use 92 because it was recommended! The theory given by my then tuner was run the NA on the lowest grade and a Turbo on the highest grade available. There have been no problems so kept to that advice. The other theory is always go to a high volume service station as fuel can go stale.

Well you dont have to beleive me but im telling you what i got... If your jealous thats not my problem... 14.8 and it coulda gone better

Just remembered there was a previous thread on octane which pointed out octane ratings varied round the world. The fuel I use is 'regular' while the 'premium' is usually rated here as 98-100 octane.

Some 30 years ago when we first tried a turbo on my Lotus 47 we had to use premium fuel with an additive to stop the engine blowing up, I think it was methanol, which meant carrying a large can around and topping up when adding fuel at a service station. Turbo knowledge has certainly moved on from the first custom installations.

edit: nm just read ur last post... thats very odd... low here is 87, high is 92 heh

Just to be certain about octane I emailed BP and received the information their fuel here is regular 91, super 95 and premium 98 octane. It just shows how difficult comparisons are.

I can confirm that altitude does have an impact. Recently while working near the Afghan border I drove on the Karakoram highway. On the Chinese side the road reached 4,800 metres[some 15,000ft] near the K2 mountain. The vehicle was not the only thing out of breath!

Just to be certain about octane I emailed BP and received the information their fuel here is regular 91, super 95 and premium 98 octane. It just shows how difficult comparisons are.

I can confirm that altitude does have an impact. Recently while working near the Afghan border I drove on the Karakoram highway. On the Chinese side the road reached 4,800 metres[some 15,000ft] near the K2 mountain. The vehicle was not the only thing out of breath!