TheOtherEric

You're being generous! It actually adds 0.15 liters of displacement, seriously.

tmw157

yeah, I never did expect a big power increase. The kit was added because I needed new cylinders and it was only a bit more for the 3.8

I'd be happy with 250-260 at the wheels....220 was major disappointment!

Carm, do you have RS cams? any headwork?

Most of my driving is spirited country road in the mountainous part of NW jersey, and it's a blast! I didn't think cams and headwork were gonna make me happy as I basically live between 4-5,000 rpm with occasional runs to 6000 and don't really want all that power at the top. A nice smooth increase in torque with a bit of a boost in power would be nice.

CarmG993

I dug up the paperwork and here is some of what was done by Andial -

3.8 SuperCup P&C set, lightweight pistons
Lightweight Carrillo Rods
Sports Cams RS
Lightweight Flywheel & SportDisc
8:32 R&P
Quaiffe Limited Slip
Polish and Port Heads
Polish Inside Case
Micro Polish Engine

tmw157

Sounds like a terrific car!

Primeraman

Maybe a stupid question. But I have been researching the 993 3.8 conversion and can't find many threads on here going into specifics. My question is if you do the head rebuild with some sort of new cams (more aggresive like the RS) along with the 3.8 bottom end conversion does this change the redline of the car as well. I know it changes how the power is put down throughout the powerband. I just keep dreaming of what it would be like to drive a higher revving 993.

Also, I have done a ton of searching on this site as well as the search engines to find what I could about various 3.8l conversions but if anyone has any specific threads or sites I would love to take a look at them.

Geoffrey

A healthy completely stock 964 engine will produce 225-230 on a Dynapack Dyno. We've done a number of them over the years and that is the power spread we've seen. The Dynapack has a built in wide band lambda sensor which could have been used.

If you install the RS camshafts, yes, the powerband will be shifted up in the RPM range, however, the 993 crankshaft, and moreso, the 993 stock connecting rods cannot sufficiently support the heavy Mahle pistons and the forces at higher RPMs. Further, the stock valve springs at the stock installed height will not be sufficient to properly control the valves much above 7000rpm.

Steve Weiner-Rennsport Systems

Good point Geoffrey,....

We always use Pauter or Carrillo rods, JW rod bearings, and better valve springs & retainers for all 3.8 conversions. Further, the crankshaft gets cross-drilled and the case/main bearings are modified for improved oiling.

The 993 crankshaft is very reliable with all of the above mods using RS cams since its over the power peak by 7K,....

Primeraman

So what you're saying is that if you basically do a full bottom end rebuild, rods and all, and a full head build that you would safely raise the redline to take full advantage of the new powerband? Have any members done such a build, and don't flame me bc I have actually searched and like I said I can't seem to find much. Thanks guys

JDHertz11

61 Cubic Inches per Litre? .15 additional Litre's?

9.15 Cubic Inches...?

Geoffrey

a 3.6l engine has a 76.4mm stroke and a 100mm bore which is 3600cc
a 3.8l engine has a 76.4mm stroke and a 102mm bore which is 3746cc

that is 146cc of additional displacement!

Tom W

Primeraman: Building a stronger engine is not always simply about taking advantage of a change in power band.

My engine is 3.6 and not 3.8 but it was built to be able to rev higher and last longer. If you do a search, you find the dyno results from a couple months ago. What that means is that the power band is pretty much the same as a stock engine but the internal components are stronger (rods, rod bolts, springs, etc) so if I miss a shift I don't destroy my engine. While shifting normally occurs at 6500 rpm, I have the rev limiter set to 7400 rpm. I have missed a shift and hit 8200 rpm with no problems because of it. The engine was built this was due to race class rules, a desire to have 100 hours or so between rebuilds and the missed shift protection.

Primeraman

I see....thank you.

tmw157

leakdown + Compression

#1 215 2%
#2 215 2%
#3 210 2%
#4 210 2%
#5 215 2%
#6 210 2%

My max power is actually 235rwhp, not 220 as I initially reported. No OBD codes found.
This car runs well and idles smoothly, it's an overall joy to drive so I'm hard pressed to call it "sick".

I've been out of touch with the mechanic but will speak to him next week. I don't know what his thoughts are re: cam timing, varioram, resonance flap and a few other issues which may be causing my low power.

Or perhaps my limitations are caused solely by my incorrectly mapped ecu?

The tuner said I have a very early OBDII with an early software version of 5.2 (or 5.02) versus the 5.2.2 he usually sees on a 1997 993, and he was unable to crack the code. The Bosch part # 0261204376 would indicate it is remappable according to Steve. So as soon as I'm able to determine if there are other issues that are holding this car back, I'll see if Steve can work with this ecu.

Meanwhile, what do you make of the following charts? Does the flattening of the power curve at 5200 look like a varioram problem?

thanks,
Todd

axl911

The car is running really lean! But look at the generous torque curve. A chip would probably help alot here and bump things up quite nicely. Right?

Steve Weiner-Rennsport Systems

Hi Todd,

The HP & torque curves look normal for a properly functioning 993, but the AFR's appear to be lean. I would be confirming that the primary oxysensors are working properly and the intake system is free of any air (vacuum) leaks.

These issues need to be thoroughly checked out before your .376 ECU is reprogrammed.