por9146gt

Can someone with experience please advise me on my 2 lit 914-6 gt.
Finally found some 46 webers, idles great, revs in the garage nicely with a little puf of black, so it is a little rich. on the road if at 4000 rpm and you accelerate hard it falls on its face, if you bring the rpms slowly and gradually it is ok. mains are 160 now, f24 emulsions with 180 correction.
I have turned down the acceleration pump down to 8ml.....it was 10, it is almost as low as I can get it. We live at 4500 feet. Can someone give me an idea what the specs should be for a 2 lit. and where I can go from here. I have not tested the car since turning down the acc el pump.
any info is great....
thanks

Steve Weiner-Rennsport Systems

What cams & compression ratio do you have?

por9146gt

Hi Steve,

Compression is 11/1...............cams are GE 8o

Steve Weiner-Rennsport Systems

OK,....

Please bear in mind that your exhaust system plays a very big role in final jetting,... If you are using megaphones or separate mufflers with no crossover, you will never get decent throttle response and power in the midrange. Its VERY critical with those cams.

Given your altitude, I would try F3 emulsion tubes to pick up that throttle response.

Your jets are very close. I'd try some 155 mains, too.

por9146gt

Thanks Steve,
I beleive you are correct. We went to the trans am invitational and played with the mains, and then with air correction on the f24, was going towardwhat you are advising, looks like a pressure fed tensioner (new) went south on me, so I am back home, I am using phase 9 mufflers and no cross over , but will ad one, what about the venturie size keep at 36???

Steve Weiner-Rennsport Systems

An exhaust crossover makes a VERY big difference in the 2000-5000 range with these engines.

I would use either 38mm or 40mm venturies. Remember, the 210-HP 906/911R used 42mm ones,....

por9146gt

excellent thank you so much....
I am assuming that the main jets may need to be different if the venturies are larger,and how will that affect the overall response of the engine, will it be even more peaky? and the exhaust cross over is it best at the base of the mufflers?

Glen

What dia exhaust are You using. I would concur on the f3's and definitely 38-40 on the vents. The crossover we put right at the end of the header just prior to the flange. We found the Bursch 1.5" 914-6 headers were a cheap date that worked well on the 2.2 I raced for a few years.

Glen

double-clickitis...

por9146gt

not sure I agree with him....I had f3 in it, but needed to play with the air corrections. could not because the engine go noisy, and we tore it down, all the rod bearings are gone(new motor), not sure what caused it, checked every oil galley, etc. next is the new carrera pump and tank. Should be back together soon, ....tell me where your power band was on your motor....tq/hp....thanks.............are you still running your shop top or did you sell it and move on?

Glen

Before You put it back together You may want to use a 993 oil pump or even better the 996 GT3R dual scavenge works great. Also make sure to have 993 Twin Turbo squirters installed in your case, keeping the piston bottoms cooler is worth 5hp easy. We ran it for 4 yrs with no failures and broke a bunch of the"rules" at the time. We used stock rods, stock rod bolts, shifted at 8000 and a non counterweighted crank. We ran a milder cam than You more along the S+2 or so. the power was 5-8k and the crossover with the smaller tube headers really helped the bottom end. We found we gave up very little if any at the top but gained quite a bit at the bottom with the smaller tube exhaust, crossover and milder cam. Seems like we liked 155-160 mains, 38 vents, thought it was a f3 but could have been f24 and maybe a 170-180 AC That is all off of memory so please dont hang your hat on it. It was a great car, sold it a couple of years ago and built a 993 RSC4S 3.8 and then a 993 TT in C, now I run an 01 CUp. There is nothing better than a 914 in the twisties, I had 11 inch slicks on the front and 13's on the back. It was nicknamed the Flounder, in fact after 9-11 my wife and I got hammered on wine and spray painted it with Walmart's finest for a special"Patriotic" appearance....

http://groups.msn.com/porschenut/por...oto&PhotoID=13

http://groups.msn.com/porschenut/por...oto&PhotoID=14

por9146gt

Thanks Glen for the reply,
looks like some of my other post did not type in, what I started saying is that my local mech here is reluctant to go from 36 to 38 vents and that I did not agree with him.....anyway your info at least puts me in the ballpark.
We are looking forward to getting this vintage car going.......
Hope to see you at one of the races, maybe Pueblo.........

dbanazek

I was running a 2.8l with elgin 314 cams and weber 46s here in Denver. The cams are very close to yours. No power below 6000 rpm. I tried 40 & 42mm chokes. The 40's picked up power a little below 6000 but it was still unsuably low for racing. I think I ended up with 185 jets with the bigger chokes.

I learned a lot about my motor on the chassis dyno. Bear at Dyno Pro is nice and has an air fuel monitor that he can plot out along with you HP and torque.

I have a shop here in Denver and can help you at the dyno if you need it.

I blew up my 2.8 and am now working on a 3.4.

por9146gt

Hi Dave

must did the exhaust cross over as per Steve's recommendation, also went to the f3 with still my 36 venturies......mains are at 160 now....yours was a 2.8 and this a 2.o liter....Now, just took the car for a drive....it has a real bad flat spot 2500-3000...after that it runs like a bandit(thanks to all that helped it is awsome), I changed my corrections from 180 to 170 (all I have to go rich) to see if it improves , the A/F guage was fluctuating indicating it could use more gas....noticed a slight improvement but not muchnot much.I would like to go to 38 venturies but would like to deal with one challenge at a time. The flat spot will transition slowly at part throttle, but if you are in it and floor it, it just gets worse and stays there, also get lots of spitting back in the carbs, I know I won't use it racing, but would like to get things better..... so any more insight is helpful, dyno time sounds like a good idea, I may be coming up friday to Denver for the vintage race....thanks again to all..........