The Beaver

'88 Carrera supercharger. Where can I obtain a supercharger kit to fit an '88 Carrera cabriolet with air con?

My87Targa

if you find one please let me know ive been on the search for one for my 87 for some time now.

DonMo

Have you ever wondered why you can find a bunch of turbos and very few superchargers? There is a reason.

wheatdog

I don't think they have a website but they used to have a couple of kits for 3.2 motronic applications; one Vortec and one Paxton . Very nice stuff. Expensive too. They may not carry the 3.2 kits anymore. I've seen the 3.6 kits recently though but don't remember where. Try a search on superchargers here and on Pelican.

Mike

My87Targa

theres actually only a sparse few turbo kits for N\A cars to use. dont know why the 3.2 seems to be more tune friendly then a stock turbo. i may be wrong but i see alot of people useing a bunch of stuff from the 3.2 for their turbo.

oh and anything for a porsche is expensive lol

Shark

What he's saying is '88 engine + supercharger = BOOM

Now we have this discussion all the time on the 996 forum. The only safe way to add a blower is to reduce the compression ratio to about where the turbo is.

84_Carrera

As a matter of general statement, I disagree with you.

In non-911 6-cylinder engines, I've personally built up stock 9.8:1 / 3.2L / 220hp engines with centrifugal superchargers running up to 10psi of boost, netting ~320hp at the wheels. No longblock mods at all, and this was using a PCM dating to 1989-era (EEC-IV / OBD-I) with a simple chip, larger MAF & injectors (24 lb-hr stock & ~32lb-hr for the 9psi). I personally felt this was a bit too close to the limit after the build, but in the SHO community I've advocated 6psi to a max of 9psi on non-intercooled boost for years. I did go with forged pistons & dropped the CR to 9.0:1 on my own car when I considered going to 15psi on my track SHO. This achieved 419hp at the wheels - non-cooled, with Accel 48 lb-hr injectors & the Vortech V1 S-Trim. With advancements in lower-cost PCM program overriding now (TwEECer, etc.), you can do more than before & make it a much more efficient setup. I know mine was running as rich as 10.2:1 A/F at one point.

As for air-cooled engines specifically, I don't know where you start to run into detonation issues due to heat, but replacement injectors aren't going to be an issue, I'm going to guess cooler heat range plugs are available; the DME cars can obviously be tweaked to deal with the new config, and I'd hazard a guess that the fuel pressure regulator can be readily replaced with a fully adjustable unit for the application. Space restrictions & the years of turbo know-how would be my guess on two reasons cent. superchargers haven't flown well. To me, there should be enough room where the AC compressor is to route the piping well enough if someone were so motivated.

I would imagine that the 915 trans would not like the extra torque though. I know the stock SHO trans tended to give up 3rd gear to the torque gods at around 290-300 lb-ft unless you replaced the entire gearset with a $6000 aftermarket setup. Stripping 3rd gear twice was why I sold the track car & invested in the 911 I have now.

Personally, I'd love to see my 911 with about 300hp & say, 2600lb chassis weight. I can get a 9" wheel on her RWD setup, where I could only get an 8" wheel on the SHO's FWD config, making it easier to harness & use the power more effectively.

Anyway, just grumblings from the unwashed heathen here, pay no mind.

My87Targa

and why would it go boom??? the comp ratio isnt even that high. unless from 87 to 88 it changed isnt it like 9.5 : 1?? some colder plugs maybe and a better fule pressure regulator. if anything bigger injectors, and a good fule pump and you would be set.

you cant compare a 996 to an air cooled 3.2 motor.

also whats the turbos comp ratio?? if there are turbo cars running around 10 : 1 or 11 : 1 out there then i see no problem with a blower on a pretty lightly modded 3.2

84_Carrera

One other thought, you're not going to run a charger with the standard V-belt the AC runs on. I had a 6-rib serpentine pulley on my Vortech, and at 11psi I'd start to see some slippage unless it was really socked down & using belt dressing. So, you'd be talking a different crank / alt pulley perhaps, & running a single serpentine 6-rib or similar. With the AC location being horizontally across from the alt fan, you might need an idler pulley between the two to get more wrappage there, and again after the charger before the crank.

My87Targa

most blowers ive seen on 3.2s have all been on the side of the motor where the heat goes. and id guess that you would need a different lower pully if you were to run anything above like 6 psi of boost

LaughaC

I just had an email exchange about this yesterday. Here is what a mechanic in Boston said when he sent this photo:

"...the 3.2 will have to have raceware rod bolts to be reliable enough to twist past 6500 rpm or otherwise they become grenades. The 3.0 can be made to run in 3.2 trim and it can be wound up to 8000 rpm without failure just be sure that the rod bolts are also replaced and your valve train is new not used."

Kevin Michael

Judging from the hogged-up mess on that inter-cooler piping, I would'nt let that guy touch my engine.

theiceman

holy crap is that a Porsche engine ? good job it had the fan i recognise or I never would have known..

johnnyo

As far as rod bolts go, they are only affected by rpm not torque, with supercharging rpms should still remain below the red line, remember its not like a turbo where boost is related to spool up at a higher engine rpm to achieve boost, with supercharging boost is instantaneous (no lag) and at lower rpms by the time you reach the higher rpms you will be flying, this said as long as you remain below 6600 rpms your rod bolts will not know the difference even when increasing HP by 100-150, Just for the hell of it look at Knight industries electric superchargers, utilizes three 8hp electric motors powering an eaton roots type supercharger yielding 8 pounds of boost with no parasitic losses from a pulley system, quite ingenious for those few 15 second bursts. Not looking to start a debate here, but only to introduce interesting concept

84_Carrera

Sorry, not quite accurate.

Roots-type / Eaton-type offer positive displacement, and a large increase in torque at lower RPMs. Centrifugal superchargers offer progressive increases as RPMs increase, and nearly nothing at idle.

Here's a pretty typical SHO engine. Notice the low-rpm intake runners are running out of steam by 3500, the secondary runners open up just before 4,000 in this case, building the 2nd torque curve, which is all done before 6,000, where peak hp falls off.



Now look at a similar engine, Vortech-equipped. The blower provides an increase in airflow progressively, keeping the engine going up to the "pull-the-pin" point - hp is linear, unlike before, as the engine continues to get fed more air corresponding to the rpms.



Now add headers & a true-duals setup that breathes better, and more gains can be found as the system leans out. No change in electronic tuning between the two configurations, just mechanical tuning of the exhaust. Please note the belt begins to slip around 11psi / 6250. The complete line run saw 15psi of boost. On some of the lower boost engines I've worked on, the curves are similar, with a small fall-off near redline. Obviously the numbers are different, but the curve shapes are similar.



Interestingly, my '84 911's hp curve is VERY similar to the supercharged SHO's, a near-straight line continuing up to redline, as the torque doesn't really fall off sharply even over 6k rpms.