Engine mods, getting ready for a new track season

[michael lang]

Disclaimer: I had this thread started in the engine building forum but decided to move it over here.


Normally my offseason MO is to pick one area on my car that I modify and then understand how that has changed my car on the track. I usually only go for one or two components at a time but this year I have decided to really jump in. Since my car is having some body repairs completed and the drivetrain is out, I decided to make the more use of the engine. The engine I have is a stock 3.2l with a Euro per-muffler and a Bursch muffler. Very plain and extremely reliable. My goals are relatively modest, I am focusing on cams, exhaust and tuning. I am going for 250 bhp. I have not decided which exhaust to go with but I really like Brian's (Rarely8) headers so that's probably what I'll end up with. I already have 964 cams and once everything is back together I will have a chip made to compliment what upgrades have been performed.

As I said, I purchased the cams thinking I am headed in the right direction of meeting my goals but I'm ashamed to admit, I really don't know how the cams work. Can someone explain how changing the cams will affect the performance on these engines and what changes I can expect by putting the different cam in my engine? I've only read in the various posts that this is the thing to do. One of the things that I like most is that my engine is bullet proof. I really like that I can beat on this thing all weekend long at the track and it just doesn't break. In fact, my car runs much better at the end of the weekend than at the beginning of the weekend. By installing 964 cams, will I be running the risk of giving up the reliability that I have become accustomed to? I also would like to know what if anything else I will need to install with the new cams. Am I correct in assuming that these things are not plug and play?

I know with 100% certainty there will be a lot of good questions that come up as I go along and there will be some really stupid ones so I ask for everyone's patience while I work through this. Over the the last nine years I have read about guys redoing stuff on their cars and this board has always come through for them with their knowledge and experience, I can only wish for the same thing for me while I go through this.

Many thanks in advance.

[Elombard]

I think Steve Wongs (911 Chips) Website shows dyno graphs way over 250 hp with bolt ons? Just add headers open exhaust, hi octane fuel and you are there?

The cam change works by opening the valve higher and longer so more air can come in and more exhaust can go out. Add more fuel to the extra air and you get a bigger boom and more power....if everything is working properly together. In reality its very complex and perhaps some experts can give you more detail.

One thing to keep in mind is that racing motors that operate always in high RPM like very different cams then a street car and the OEMs are very restricted with cams because it has a big impact on emissions and gas mileage.

I think I have read that the 964 cams have some worthwhile benefits for motronic motors but Porsche did not leave too much on the table. You will spend quite a lot of money and effort with out too much benefit.

If you really want to go fast bump it up to 3.4 liters, twin plug and add ITB aftermarket injection and every thing that goes with it including bigger valves higher compression and high overlap cams etc. Probably cant get through emissions with that if its an issue.

In the end the 3.6 liter 964/993 motor swap looks pretty attractive value wise.

[GaryR]

If it's a US 3.2 dropping in Euro 10.3:1 Mahles, custom cams from Doherty, MK headers, custom chip from Steve W. (will require a couple dyno visits) and you may see your 250+ HP (BHP, not RWHP).

[skinnerd]

I had 3.2 Motronic with the 964 cams, larger throttle body, Wong chip, SSI's and nice sport exhaust.
I think I was right at 235hp.

Not sure 250hp is attainable without really going inside the engine and making a lot of drastic changes.

Remember the 3.6 engine in the 964 was "only" making about 250hp (crank) and that has a lot of displacement advantage over a 3.2.

[michael lang]

Erik, thanks for the input. It sounds like if I'm to continue on with this I will need to address the fuel system to somehow get more fuel into the engine for everything to work together correctly.
Doug, when you had your 3.2l, what did you like about how you had it set up? 235bhp is a fairly respectable number number, when did it really come alive? Was the power band as predictable with the 964 cams as a stock motor?
Gary, I believe the cams that I have a just a stock 964 cam with the power steering drive cut off.

[skinnerd]

The engine pulled well from 3000rpm to redline (6800 rpm).
Powerband was better than stock....but just a little bit.

Started easily, got great gas mileage (~30 mpg on the highway), and sounded great with the SSI's and sport exhaust.

It was a great engine....used a lot for auto-x, track days and around town stuff.

Rev'd pretty nicely for a non MFI/carb motor too as I remember.

Not much not too like about that engine.

[michael lang]

Thanks Doug. So this leads into the whole "while you were in there" thing. Is there anything else that I will need to do to my car's engine in order for the cams to work properly and also not give up on any reliability the engine has?

[Elombard]

Actually the re-mapped chip takes care of the fueling. I believe for 964 cams the rest of the 3.2 fuel system is up to the task. When you do the top end tear down to install the cams will you address valve guides? Also good time to go with the euro compression pistons.

[mnez]

Mike, as a data point.


I had my engine done a few years back. It dyno'd at 245 rear wheel HP.
We did the following:
Autothority MAF
Enlarged throttle body
Extrude Honed intake manifold
WebCam 20/21 cams and a little porting
Malhe 3.4 litre 9.8:1 P&C set
SSI exhaust (I need heat)
Sachs aluminum body Power Clutch kit
Dansk 2in 2out muffler
Steve Wong custom chip.

The chip required 2 remaps, which improved drivability and power delivery.
It wasn't cheap, but it goes well.
Unfortunately, the old tranny couldn't really take the torque, and failed.

[michael lang]

Thanks for the input, after going through all that, do you feel like the results were worth the effort/expense?

[mnez]

Mike,
I had someone who knows what they are doing build it, so my effort was limited to research, parts procurement, and re and re the engine/trans, all fun. As for expense, well, is hard to say. Mine was more because it wasn't DIY. I'm happy with the result. It pulls away (a little) from my friend's 964 with a 3.6 varioram (also some gearing advantage). In the end it's a hobby and the money was earmarked for it. Gotta spend it somewhere. Don't regret it.

[Devil Dog Mosport]

Originally Posted by mnez

Mike, as a data point.


I had my engine done a few years back. It dyno'd at 245 rear wheel HP.
We did the following:
Autothority MAF
Enlarged throttle body
Extrude Honed intake manifold
WebCam 20/21 cams and a little porting
Malhe 3.4 litre 9.8:1 P&C set
SSI exhaust (I need heat)
Sachs aluminum body Power Clutch kit
Dansk 2in 2out muffler
Steve Wong custom chip.

The chip required 2 remaps, which improved drivability and power delivery.
It wasn't cheap, but it goes well.
Unfortunately, the old tranny couldn't really take the torque, and failed.

Just curious.. With the Autothority MAF comes a "chip" to operate the MAF properly.. Why did you use the SW Chip instead?

[Joe Bob]

Always check the rules for the class you are racing in. Some engine mods can put you in the "open yer wallet" class and you will NEVER be competitive.

I always go for weight reduction and suspension upgrades first.

Good luck.

[michael lang]

Thanks Joe Bob, normally I would go in that direction as well but with the drivetrain out and my car's body getting some facelift done I thought I would take advantage of having the motor out and do some upgrades to it.

[mnez]

Originally Posted by Devil Dog Mosport

Just curious.. With the Autothority MAF comes a "chip" to operate the MAF properly.. Why did you use the SW Chip instead?

Two reasons. The chip was mapped for 93 octane. And there were so many other changes that custom A/F ratio tuning was necessary. The Autothority chip was designed around stock intake/exhaust/cams (as far as I know). I didn't even try it. Steve sent me a chip based on his experience and my mods, and then we did 2 revisions with dyno AFR data.

[Devil Dog Mosport]

[QUOTE=mnez;7861993]

Ah ha...okay makes sense! Did you really notice the difference with the new MAF? Without the "trap door" on the stock MAF, the flow response must be smoother and quicker..

thanks

[mnez]

I wouldn't say the throttle response is any quicker or smoother. And I can't say what contribution the MAF would have made all by itself. But it made sense (to me) in the context of total modifications to try and flow more air through the engine.

[michael lang]

That's exactly what my thought was as well.