llthomas

Hi everyone, if you had the money to spend, what upgrades would you make to the engine of your 90+ c/4? I know about the air intake, exhaust, and ecu, but what I am looking for is the real gearhead out there that put in a different cam , with 3.8 cylinders, or all that plus a different crank? Anyone have any ideas? Or has anyone tried something and had it not work out? Are there options for this motor besides a chip and the usual blah blah??

hawk911

Look at Geoffrey's posts; that's what I'd if I had the money.

chancecasey

How much do you have to spend?

(seriously, that makes it MUCH easier to answer this in a meaningful way)

also check out the engine rebuilding forum on pelicanparts.com if you haven't already.

-Chance

Tom W

My $0.02 from just having done some research and then having a new engine built ('cause mine went kaboom in a race).

Do you want power or longevity. Either will cost and they are not the same. Really pushing the envelope for power will likely reduce longevity. By that I mean building an engine that can make 8k rpm and then using it all. Runnning that hard will mean more frequent rebuilds. Building a monster engine and then running it at 6k rpm will greatly increase the time between rebuilds, but why bother?

Budget is everything. $1-2k will not get much, and from my experience you won't get squat from the ECU or air intake for this money. I only saw a benefit from a cat bypass (combined with a secondary bypass) at it was about 10 hp. $30k and up will provide real increases in power. Then you get to the stage of asking the question of why you want to spend more on the engine than the car is worth. Why not buy a different car with more power. It comes down to what you (and not someone else) wants and why and if you have the cash available to do it.

My new engine will be good to 8k, but I've had it limited to 7250 rpm to increase it's life (and I wasn't making that much power up there anyway). My goal in the build was strong to last long. It puts out 293 hp at the flywheel and the hp produced is limited by the intake system (which is limited by my race class rules). It has MoTec control instead of the Porsche Motronic ECU.

In my case, about half the cost was labor. You are better off if you can do it yourself, but I don't know to many people that can do a DIY MoTec. And, I don't see how you can put in something like a different cam without serious efforts at reprogramming (not to mention that a cam alone would not make sense, it would need to be part of an overall upgrade). It is my understanding that the parts alone in a 3.8 L kit are above $20k, so even if you could DIY, it isn't inexpensive.

kgorman

Tom, did just the cat bypass and g-pipe get you 10hp? Or does that include the MoTec changes?

Tom W

No, that was old engine. We tried various exhaust and chip mods. Cat and secondary bypass was 10 hp above other changes (including straight headers with minimal muffler). It was 235 with cat and secondary bypass 240 with headers and muffler and 245 with cat and secondary bypass (IIRC). Bottom line was headers and a chip change gave nothing (were a tad less) than stock chip and cat+ secondary bypass pipes. While I don't think it matters, I also has a K&N filter and cut away air box.

New engine with old exhaust was about the same or down a bit (dyno differences make it next to impossible to compare). The MoTec and new exhaust with other tweaks and MoTec programming on the engine dyno gave 50 hp about the motronic (old exhaust and motronic was about 243 and MoTec was 293 hp - both at the flywheel on the same engine dyno under the same conditions).

kgorman

Wow! Thx for the info.. Q: 243hp ~= 267whp? I always get confused on that..

Chris M.

Check out the "engine upgrade 993" thread on the 993 board. Colin at 9M in England is doing custom cylinder heads (Geoffrey got his heads from Colin) plus other things to give 350 NA hp on a Varioram 993. Another 95 993 owner is taking his in for the same thing soon and expects to get the same...hello 964!! It's not cheap of course, around $18K. I guess you could get an SC or even turbo conversion for less but I like the idea of it looking totally stock and being NA. Anyway, check it out.

c

ThomasC2

If I had the money I would go for a 3,8 L upgrade without a doubt. real power and more torque. If even more money other camshafts and a hot film AFM. If even more money, a full Motec set up.

robmug

I think I'd go for a supercharger. Make sure the engine is in reasonable health first.

Geoffrey

If it were me, and this was a street car, I would rebuild the engine to 3.6l spec ensuring I had exactly 11.3:1 compression, not the 10.5-10.7 they normally are. I'd service the heads and port them just enough to clean up the flow, do a very nice multi radius valve job, install a set of custom camshafts matched to the flow of the heads. I'd use a plastic 3.6 manifold (if found economically), remove the cat (or install 100 cell cats), and a use a free flowing exhaust system. I'd install the RS lightweight clutch/flywheel assembly and I'd either reprogram the original ECU or replace with a MoTeC ECU.

Given a choice of spending 4.5k on 3.8 cylinders, or 4.5k on a MoTeC ECU, I'd pick the MoTeC ECU as I think it would be a better value. Money no object, the old addage "no substitute for displacement" is true, however, the 3.8 cylinders bring with them some compromizes and for a street car I don't necessarily see the benefit, especially when cost is factored in. You are talking about 3600cc in a 3.6l vs 3746cc in a 3.8l so it really is only .146l larger.

Christer

where are you llthomas?

BLK964

Maybe a dumb question, but has anybody ever went with a supercharger and Motec?

Geoffrey

I attempted to put MoTeC on a supercharged car but it was a disaster I found the engine would only take 6 degrees of timing under 4psi of boost, that's right 6 degrees. Further, even with an intercooler, I could not keep the engine intake air temps under 160 degrees in a track environment. I was not running the 7th injector which I have now come to believe is more for charge air cooling than extra fueling. It did produce 360+hp with open exhaust.

chancecasey

Mahle 3.8s are a HUGE expense ($4700) so if going aftermarket, go ahead and get the 3.9 set (about $2300). But you'll be lucky to get 10 or 15 HP at the peak and a little bump on the torque along the powerband if that's all you do because nothing else is set up to take advantage. I think it would be a waste of time if you didn't combine this mod with better cams ($250-$600), porting (I have no idea, maybe $1000?) and free up the exhaust a bit ($500). Of course now that your engine is completely different, you WILL need a new ECU or just a custom chip for the existing one ($500). I think you couuld realistically knock on the 300HP door if all this is done well.

If you want the engine to hold up to this increased power you at least need to upgrade the rod bolts, head studs, and depending on your cams, better valve springs. ($1200)

Since you've upgraded the components, now just get everything balanced and increase the rev about 1000. Definitely over the 300HP mark now. ($1500)

We're definitely not worried about emissions now - and we're spending all or our time above 5000 RPM (we're a hairy beast who doesn't drive in traffic) so let's slap on some 46mm PMOs ($3500) and make it easier to tune this baby for each new mod. Now we can really have 350HP @ 7500 RPM at the crank. Oh we might need to re-port the heads to take advantage of the increased RPM and carbs ($1000?)

Ahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh!

Sorry I just had to share a snippet of my line of thinking when I was considering this upgrade. I really REALLY wanted to upgrade because I was already completely tearing down my engine. I agonized over this for weeks before finally concluding that none of these upgrades are for me - not yet. I will wait until my engine is completely toasted, and then think of a better $/HP route to getting more power (new engine or new car, likely).

If you crave "that feeling" - might I recommend you keep your engine stock and spend the money on track days? I can almost guarantee you'll have more fun spending $1000 on 4 or 5 track days with that puppy than you would squeaking out 10 extra HP on the street. I would be shocked and amazed if you even noticed the HP difference - 10HP only a 3.4% increase after powertrain loss. If you haven't been on a regulation FIA road racing track in a nice machine like the 964, I must warn you, it's like heroin. If that sounds cool, PM me and I'll be more than happy to get you addicted to a pusher near you.