993 turbo vs non turbo engine parts

adamb113 · 03-20-2005, 05:26 AM

How different are the Turbo vs non Turbo 993 engines?
What I'm getting at is when these guys are slapping Superchargers on 993 motors are they able to handle the Turbo equivalent HP the same way or is there going to be some premature wear?

Is the Tranny the same too?

beepbeep · 03-20-2005, 06:53 AM

Turbo engines have only one set of plugs (they are not twin-plugged) and lower C/R pistons.

That being said, N/A 3.6L engine is a very good candidatore for turbo-conversion provided you swap out the pistons to lower C/R ones.

KNIGHTRACE · KNIGHTRACE's Garage

Turbos are the way to go, superchargers pump extra heat into the motor any time it is running, Superchargers use 33% of your crank power, turbos use 11% of your crank power. Turbos only work when you need them. There is no heat difference in compresed air tempature from turbos or superchargers, they heat the same when compressed.
On an aircooled motor you dont want to go over 140 F on your intake charge. A 3.6 @ 8:1 compression with good cams large intercooler good fuel well setup will make about 645HP at the rear wheels. As for the drive the supercharger will do beeter at low speeds where you need quick response but will fall prey to the turbo on the high side. Bottom line the turbo motor will live longer and is 20% more efficient. I hope this helps, I know there is a lot of confusion about this.

kenikh · 03-20-2005, 03:20 PM

Parasitic drive loss in superchargers is really dependent on the type of supercharger you use. The numbers quoted above are relatively true for a roots type supercharger, bot not necessarily true for centrifugal superchargers, which tend to have more in common with turbos than conventional superchargers.

Roots type chargers are really nice in less torquey, smaller motors (a la Mercedes SLK). With cars with good low end torque w/o boost, but needing more on top, turbos tend to better (thus why turbos are used in modern Porsches).

I plan on building a forced induction 7R cased 2.5L and will most definitely use an Eaton M62 roots type supercharger w/ intercooler. It should pull like a big block Ford! In a 993, I would most certainly go with a turbo, though although a centrifugal charger is also enticing. Do a web search on Vortech and Powerdyne to see a few of these.

KNIGHTRACE · KNIGHTRACE's Garage

Supercharge a 7R Mag Case??? I thought even with timeserts they came apart at 270HP. I have a running 2.7 R for $1500 if you need a spare.

snowman · 03-20-2005, 05:29 PM

So whats the difference in motors??? Is the crank better, shotpeened? rods the same? Oil system and cooling the same?? Clutch, pressure plate, flywheel? Pistons forged or cast or cast but stronger? Oil clearences? valve train?

kenikh · 03-20-2005, 05:45 PM

Quote:

Originally posted by KNIGHTRACE
Supercharge a 7R Mag Case??? I thought even with timeserts they came apart at 270HP. I have a running 2.7 R for $1500 if you need a spare.

Even the CIS turbo kits make more power than that reliably. Are you sure about the 270HP limit? Shuffle pinned w/ time certs and boat tails/eyebrows should be good for more, from what I hear.

KNIGHTRACE · KNIGHTRACE's Garage

I was never aware Porsche made a Mag case turbo, and a 7R case is a late 2.7 case. The 3.0 SC case same as a 935 will hold 875Hp. It is my opinion and I was only trying to help, I would advise against forced induction on a mag case for anyone.

kenikh · 03-20-2005, 08:25 PM

I appreciate the concern; I wan't trying to sound defensive.

Porsche never did make a mag case turbo; there was an aftermarket kit that would let you take a CIS car and turbocharge it. The low compression was ideal for it. There are a number of folks on this site that have run this kit for years and tens of thousands of miles. Never seen it first hand, though; the impressions I have gotten on it are positive.

Do you have any specific experiences that would steer you away from a mag cased turbo/supercharged car? If there are valid reasons for me not to do this, better to know now than after I've invested a lot of money...

KNIGHTRACE · KNIGHTRACE's Garage

Years ago a friend of mine did a test on a 2 HSR motors, both same size,compression,ports,everything. When the Mag case motor got to operating tempatere there was 20 HP between the two. It was only like a 240HP and a 220HP motors, The mag case was expanding is what we thought. A CIS 3.0 turbo with head work and cams, intercooler, 1 bar will make an easy dependable 400hp. If you built a 2.?? magcase @ 1 bar with heads, intercooler,cams, 1 Bar. I dont think it would last a week on the street. I would think when it went up on boost a few times somthing will come loose or give. I hope I did not come across wrong. I hope you build an AL case turbo and have fun. The 935 Baby was a 2.1 and it Killed its class with about 530HP. Please use an AL case and you will love it. If I can ever help or you need parts please email me at knightrace911@hotmail.com Sincerely, William Knight

kenikh · 03-21-2005, 05:45 AM

I have a friend who wants to sell me a 7R cheap , thus the interest in the mag case, not to mention they are 20 lbs lighter than an AL case. You aren't the only one to suggest that a blown 7R isn't smart. Perhaps I will need to locate a 3.0 turbo motor, then. Or maybe I will just find an early AL 2.0 case and blow that. Recreate the 2.1 Baby; that DOES sound kinda fun.

KNIGHTRACE · KNIGHTRACE's Garage

I would get an early 78' to 80' large port 3.0 if I wanted a small turbo. Put sone 8:1 JE's in it and whaterver injection you want. Stock Exhause will make 400HP. but really anything from 78 up would work fine. The small motors will make HP but lack torque. I wouldnt do th e 7R case at any price. Find a cheap old SC motor go for it, the 82 & 83's had small ports, if you want to go stand alone injection the 3.2 is the way to go for starters, the 964 will work with Al manifolds but it takes a lot of car to hold 700HP. 930 box or G50/50 and no streeet tires.

kenikh · 03-21-2005, 08:33 AM

I have been browsing the site, looking for reliable evidence of the mag cased 2.7 turbo. There are quite a few out there; search "BAE turbo". Still, your point is well taken: why take chances?

g8keapor · 11-19-2010, 06:59 AM

Too bad this thread was hijacked by people discussing older motors. The question here was what are the differences in engine parts between a 993 na engine and a turbo. aside from being single plug im pretty sure the heads are entirely different. That being said I have seen alot of the turbo heads where the second plug was later added. The valves from what I see have different part numbers the cams are different. so there are major differences in the engines. The only thing I see that looks the same depending on what year engine you have is the crank case and possibly the jugs. Hope that answers your question from way back in 2005. Also the only reason for going low compression with a turbo is cause you arent great at tuning. It is safer if you don't have the knowledge in tuning however a higher compression boost motor will produce more power! At anyrate this thread made me full of angst because I was looking for similar answers when i first read this and after just going into a parts database and comparing part numbers I figured I would reply here to this thread and end the hijcaking.

lucittm · lucittm's Garage

The turbo heads use a different alloy of aluminum designed to be more resistant to higher temperatures as encountered in the forced air induction cars. There are several part numbers over the years , but I look for the "RR350" designation, see below:

Good Luck,
Mark

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by adamb113

How different are the Turbo vs non Turbo 993 engines?
What I'm getting at is when these guys are slapping Superchargers on 993 motors are they able to handle the Turbo equivalent HP the same way or is there going to be some premature wear?

Is the Tranny the same too?

993 n/a and tt use the same crank, rods, bearings, oil pump etc.

pistons, heads, valves are different

n/a 993 heads are also RR350 alloy(it was the first n/a use of this alloy), but are twin plug unlike tt

the trans is also the same g64 w/ different gearing

Ronnie's.930 · 11-20-2010, 02:20 PM

Did you guys see that this was a five year old thread that that g8keaper brought up for some reason?

K24madness · 11-20-2010, 04:33 PM

It also appears that the pistons are the same material as well. I had them side by side and the NA looks to be from the same cast. Yes cast! Most think the 993tt is forged but looking at both of them closely I think they are cast hypereutectic pistons.

Flieger · Flieger's Garage

Does hypereutectic refer to carbon or silicon here?

K24madness · 11-20-2010, 10:07 PM

Quote:

Originally Posted by Flieger

Does hypereutectic refer to carbon or silicon here?

Silicon