schnele

911rudy I am afraid I have to disagree with you. I do not have a degree in fluid dynamics but in the simplest terms think of a wet/dry vac with nothing in the hose, now immerse the hose, there will be a load on the vac and drag created by the water flow so I would assume a pressure loss. If you hook a pump up to force that water through the hose the pressure loss will be a function of the flow characteristics but also, the air temp/charge will be lower/denser therefore more efficient. The I/C on its own will not show a discernable difference in performance but will allow you to run sustained higher boost levels without melting stuff. imho

911rudy

I don't think we are disagreeing. I said that with larger IC the time to reach boost must go up because of the distance travled by the air charge is longer than with a smaller IC with a thinner core provided the cooling circuit is of the same type. The net results of a more efficient IC will ofcourse be a cooler air charge and the repeatability of the IC to provide a cooler charge will be greater than a small IC without much heat sink capacity. I was addressing the tendency for most of us to buy a bigger IC, turbo, headers, etc with the intention of lowering the onboost rpm. Most of us will fail even though we will have a better engine with improved performance. I would trade all of that for a 1000 rpm drop in onboost rpm. It would make these cars so much more streetable. Read the Feb issue of Excellence about the guy who put a 993 engine/tran in an old 911 E! He has torque in any gear and at low rpms. The description of the power is constant and linear. That is what I wish we could obtain with these old cars.

nathanUK '81 930 G50

The chap was asking about turbo & possibly headers.
"Can you just toss a new K27 HF "S" onto a totally stock 3.3 in place of the original turbo and see/feel any real performance gain? How about headers/K27?"

The question I answered was about the K26 vs the K27HFS, I didn't mention IC's, only that the K27HFS will give lower pre IC temperatures as the K27HFS turbo will not produce as much heat as the K26 at high bhp. I agree with you that the bigger the IC then there will be more lag. Air compresses, so the bigger the volume the more air needed to compress which will take time. However, people have said it is not noticable.

nathanUK '81 930 G50

Rudy, it sounds as though you would enjoy a supercharged 3.2 carrera.
This is why I haven't sold my 3.2, it has a razor sharp throttle.

I guess you could always lower your boost, bump up your CR and have big bore pistons.

Whatever you do (even a 3.6 transplant) you add more weight

RarlyL8

As I said on page 1, using a 930 single turbo CIS engine, boost threshold can be minimized to the point of seamless.
You must purchase parts that work well together and tune the "system". Headers are essential in order to minimize the distance between the heads and the turbo. The A/F ratio must be perfect thrughought the rpm band and the turbo must be capable of delivering mid-range boost.
Stephen (iA) can tell you all about it.

johnf3488

Any suggestions, please, on who you would trust the following work to: new gearsets (2,3, 4th or 8:39 R&P? About what should it cost? Can you ignore changing 2-4 gearsets if you change the R&P? Thanks, John

alexslope

Yes, the ring and pinion is one option and the gear sets are another...in an effort to make the gears more 'useable' for non autobahn driving. If you do both (I dont think anyone one recommends this), I'm guessing 4th gear would redline at 85-90mph? With the R&P, redline with my 930 is around 145ish mph.

If I were to do all over again, instead of the 8:39, I would shorten 1,2, and 3 only and leave myself the stock freeway gear (4th).

RarlyL8

What is the gear spread when using an 8:39? What rpm is redline at 145mph?

alexslope

oem gear spread. 6650 rpm redline.

RarlyL8

Sorry, I was not clear.
What speeds do you see at 6500rpm in each of the 4 gears using an 8:39 R&P?