Euro pistons plus cam =? hp

[Roamer]

I am thinking about incremental power increases to my 86 3.2 and was wondering if swapping Euro pistons in with a more aggressive cam would be worthwhile. I would also have my chip re-programmed by Steve W for the new hardware. My question is would it be realistic to expect 250hp from Euro pistons, SSIs, a GE-60, 20/21 or S cam and properly modified chip? If so, which cam would be best for decent torque and a little more top end. Also note that higher octane good gas is readily available here, so twin plugs should not be an issue. Thanks in advance.

[kstylianos]

I think 250 is quite possible, maybe a bit conservative for the mods you listed.

See thread: http://www.dorkiphus.com/porsche/viewtopic.php?t=369

Ted has a stock Euro 3.2 engine (stock cams, stock euro CR) stock headers, no cat and B&B muffler and an Autothority chip. He pulled 204 at the wheels (~240 flywheel) on the dyno over the summer.

I drove Richards Richards stock US 3.2 for a while and the only mods he had were the webcam 20/21 grind cams. The thing screamed right past redline, but the lower end was a little lacking for my taste. The 20/21 cams felt like they'd pull right past the redline if the limiter would let it. I'd personally would look for a cam that would offer a little more low end grunt and start tapering off around 6K. Maybe the 964 grind has this characteristic, but I have no experience nor knowledge about the 964 grind other than it's a little less aggressive then the 20/21.

With the higher CR of the Euro P's, you'll gain a little more torque throughout the RPM range, so the 20/21 may be a good choice. Hopefully others will chime in......

[1fastredsc]

All of those mods sound good, you may want to include in that list to upgrade you rod bolts to arp or raceware. This way you'll be able to raise the rev ceiling and rev the piss out of her, taking advantage of the cam's later torque curve tendencies.

[Roamer]

Thanks guys, I was hoping that combination would be fruitful. 1fast, I was also planning on doing the rod bolts when I changed the pistons. The problem with raising the rev limit is that Motronic no longer controls the motor much past 6500 since there are no values in the table above 6500 rpm, it essentially defaults to WOT mode. I may also go with 98mm P&C's with 10.2:1 pistons while I am at it.

Ultimately I would like to get into throttle bodies, twin plugs and aftermarket engine management, to get her up to around 300hp, but I want to do it at a reasonable pace.

[Wayne 962]

I'm not a huge fan of modifying the stock Motronic unit to work with a new combination. You really need hours of dyno time to get it right, and then, if you don't, your engine will detonate and destroy itself. Mods on a 3.2 should be done with something like a TEC-3 engine management system, in the ideal case...

-Wayne

[emcon5]

Originally posted by Roamer
The problem with raising the rev limit is that Motronic no longer controls the motor much past 6500 since there are no values in the table above 6500 rpm, it essentially defaults to WOT mode.

Maybe I am overlooking something, but how is this a problem?

North of 6500 rpm, you will either be WOT/WFO, or lifting to shift. I can't think of a time you would be at part throttle over 6500 rpm. Even if you were at part throttle, I don't see how having Motronic in WOT mode would hurt anything.

Please explain.

Tom

[Roamer]

Wayne, I would agree.

However, I am trying to incrimentally build the motor to the greatest extent possible to ease the impact on my pocketbook. I may forgo the P&C's and just add the cam for now, if I can do so without interference.

Ideally, I would like to build a high comp 3.4, with twin plugs, ported heads, 3-angle valve job, hotter cam (GE-60 or 20/21) TWM throttle bodies and some form of aftermarket engine management, but it is the TB's and engine management that end up costing the most dough all at once.

Charlie, do you know if Richard had to do any valve train mods or alter the timing to avoid any interference?

Thanks and keep it coming!

[Roamer]

Tom, LOL.

You are right to assume that I would be at WOT above 6500 rpm, the problem becomes that if you raise the rev limit to around 7500-8k, you now have a larger range of engine speeds that are not being accurately controlled. WOT throttle needs at 6500 are not the same as those at 7500 or 8k. You may need to back off the timing a little more and deliver more fuel, which may end up hurting your power at 6500 leaving you with a 'hole' in your power band and possibly lowering your ultimate power peak which might only come at 7200 rpm. Not to mention the fact that at those engine speeds you want to have the most control over the motor, not the least.

Also, I don't know if the rev limiter in the stock motronic can be set that high. Steve W would have to chime in on this one. . .

[kstylianos]

Charlie, do you know if Richard had to do any valve train mods or alter the timing to avoid any interference?

No, not with the 20/21. But remember, Richard's engine was a USA 3.2 with the lower CR. Can't say for sure if you'd have piston/valve clearance issues using the higher CR Euro pistons. This also depends on where you set the deck height.

My guess is you should be fine as the 20/21 cams have mild/moderate lift and overlap in comparsion to some of the wilder cams (s, e, etc), but the necessary checks are always a must before the first crank.

[Roamer]

Charlie, thanks that is good to know. I may just stick with the stock pistons with the cam as a first step, then graduate to larger P&C's with higher compression and appropriate valve relief.

[ChrisBennet]

Originally posted by Roamer
The problem with raising the rev limit is that Motronic no longer controls the motor much past 6500 since there are no values in the table above 6500 rpm, it essentially defaults to WOT mode. I may also go with 98mm P&C's with 10.2:1 pistons while I am at it.

The Motronic fuel and ignition timing maps/tables are not fixed in size. It takes more knowledge than just modifying the existing maps, but it is certainly possible.
-Chris

[Roamer]

Very interesting Chris . . .

[1fastredsc]

If you did go stand alone, it would work with the carrera components you have (intake, fuel injectors but a lot of the sensor would have to be switched to something else). Then the switch to throttle stacks would entail some program tweeking with the standalone. After that enjoy yourself.

[Roamer]

Ultimately, that is my goal, but the price of admission to TB's and aftermarket engine management is MUCHO bucks. However, they are both necessary if I want 300 N.A. hp out of this motor.

[Steve W]

Originally posted by ChrisBennet
The Motronic fuel and ignition timing maps/tables are not fixed in size. It takes more knowledge than just modifying the existing maps, but it is certainly possible.
-Chris

Ok, I know I'm late to the party here but Chris is right. The tables are not fixed in size, it just take some knowledge to know how to compute and manipulate the rpm headers to go beyond the default values. If you want part throttle maps and full throttle maps to go to 7500 rpm and beyond, it is entirely possible. In some of my chips I completely recreate new map points to give me control and resolution where I want it, and extend my wot map points beyond the oem 6400. However, Emcon5 is also right about being at full throttle past the 6400 rpm limit. Beyond the map points, the map values revert to the values right under the highest rpm point.

Also to answer Roamer's question, the max rpm limit that can be set is 10,200, essentially no limit.

[Wayne 962]

Sounds like a lot of work - I'm a big fan of the TEC-3 which gives you much, much better control than a modified system from the 1980s...

-Wayne

[Roamer]

I would agree Wayne, especially when you consider that some aftermarket engine management systems can be had for the cost of twin plugging a stock motronic ignition. However, I have been thinking about using Euro compression (10.1-10.3:1) with the 98mm pistons to forgo the need for twin plugs. The difference in hp with the lower compression is negligible. In this case, a completely re-mapped Motronic may be the answer.

Thanks Steve.

[ChrisBennet]

Originally posted by Wayne at Pelican Parts
Sounds like a lot of work - I'm a big fan of the TEC-3 which gives you much, much better control than a modified system from the 1980s...

-Wayne

True, with an aftermarket the TEC-3 setup you have control over stuff that you wouldn't have with the stock Motronic but at what cost? Thousands for the hardware and many hours on the dyno?
For the minor mods Roamer was talking about in his original post, a new Motronic chip is a better value IMO. Obviously, for his dream system with throttle bodies the aftermarket EFI is the way to go.
-Chris

[Steve W]

Both systems have their advantages and disadvantages - really depends on the extent of your mods, what you are trying to control or what additional features you want. Bottom line is that they both do the same thing in controlling fuel and ignition. Reprogramming the Motronic is very much like programming a Tec3 or Motec ect in that the success depends on the skills of the programmer. Understanding and recoding Motronics though by an individual for his one off motor is not a job for a first timer though because both Bosch and Porsche keep all their information a very closely guarded secret, and that is I suppose where aftermarket management systems have their advantage. Wayne is right about this. God know how many hundreds of hours I spent deciphering their codes. Although Chris, Thomas Owen, and I worked together with Marc Skarshinski to develop a freeware Motronic editing program, it's functions and the maps it can edit are still limited. Bernd Andritzky, who I work with on the 911 chips, and has been programming the Motronics controlled vehicles for BMW for the last 7 years, tells me about how Bosch is very secretive to BMW about of the software and coding used in their boxes, so BMW likewise is very secretive to Bosch about what they do with the software.

Motronic though, once understood, has the advantage in that it has a baseline of a multitude of data maps and calibration points that have already been worked out by the factory - warm up tables, deceleration fuel cutoffs, high temp knock protection function, ect. Todd Knighton of Promotive Engineering, one of the original Motronics hackers actually favors Motronics very much for a lot of his turbo systems due to the flexibility avalable by the system. Here's a couple of links from his forum:

http://pub12.ezboard.com/fprotomotiveasktheexpert.showMessage?topicID=168.t opic

http://pub12.ezboard.com/fprotomotiveasktheexpert.showMessage?topicID=58.to pic

[Wayne 962]

Originally posted by ChrisBennet
True, with an aftermarket the TEC-3 setup you have control over stuff that you wouldn't have with the stock Motronic but at what cost? Thousands for the hardware and many hours on the dyno?

Not true - rumour and inuendo. The TEC-3 can get you there with a pre-programmed unit from Clewett that will get you 95% of your peak HP. If you want that extra 5%, then yes, dynos are needed, but out of the box, the thing runs great on Rick's stock programs.

-Wayne