John Veninger

Mike,

There is a bunch of detailed stroker stuff if you do a search. I'll add some pictures of the "build" in the near future. There really isn't anything "trick" about my setup that hasn't been done by others.
I may have done slight modifications to what others have done, but kept to the idea of what has worked for others in the past will work for me.

Good luck with your project. Feel free to ask questions during your build. Many will respond.
So 7 liters, bigger pistons than 104, bigger stroke or both? Street car or race car?

IcemanG17

Mike
I think Todd (aka Mad Scientist) in Green Bay has made a 7 to 7.4 L sleeved 928 engine? 110mm bore I think?

Mike Simard

John, mine is a 4.28 bore with a 3.7 stroke crank. Delivery from Moldex has set the timeline, I ordered the crank early October. I've machined the cylinders completely away and am fillting steel sleeves. The car is a street car that will see track days at places like Road Atlanta. It's really tempting to build a race car and if a chassis were to become available I can't see not doing it, cars like yours are a real inspiration. I just need an excuse for my wife, fortunatly every form of bad behaiviour nowadays is actually an addiction so I need to face it, I have a race car building addiction and can't help it! My wife should have taken the Carol Smith books all over the place as a sign and she'll surely be understanding.

Iceman, yes I've seen the threads on Todd's stuff, I'll start a different thread about mine so as not to distract from John's car, his is a serious effort and deserves an unmolested thread so that he can chatter away!

Stan.Shaw@Excell.Net

What kind chassis you want? I have a GT2 prepared chassis I would consider selling so I could buy a turn key race car.... Everything but a motor in it right now

If you just want a stock rolling chassis, I have an '82 Euro my wife thinks I shouldn't have

John Veninger

poc62

JV, very very nice! How about another 2007 Road America 928 shootout!

J Fan

John Veninger

Measured this morning, it's 1/8"

John Veninger

Hi Joe,

Thanks.
Said I wasn't going back to RA until I had a stroker, so now it's time to return in 2007
Think I'll run in 2S just so I have an excuse for slower lap times than you and Mark

Benton

Thanks, John. Hopefully next year or something I can watch your taillights.

John Veninger

See you at Sebring??

hacker-pschorr

Here you go:

https://rennlist.com/forums/928-forum/312176-todd-s-website-is-finally-up-more-pictures-of-the-427-powered-928-a.html

Louie928

Brendan,
The DTA (P8Pro) does work well. I am a dealer for them, but I'd hesitate to recommend them at this time. I bought mine a few years ago and they were the hot ticket then. I got John's for him and helped as much as I could to get him set up with it. I use the P8Pro too. I've got two main problems with the P8Pro. First is the software. It is a crude attempt at porting a DOS app to Windows using (I think) VB. Some people report unexplainable crashes, but I haven't experienced that. There is almost none of the Windows capable flexibility. The real time mapping part of the program which is what you run while tuning isn't really that. You can use a separate tuning box to change injector pulse width and timing while the engine is running, but in reality, it's a cumbersome process and I abandoned trying to use the tuning box.

You can't access the actual tuning maps while the Real Time tuning app is running. You have to exit from that and get back into the main program to to change maps, then go back to the Real Time tuning app to monitor what you did. I finally developed a method which allows fairly rapid mixture optimization, but you shouldn't have to do that. The P8Pro is supposed to be able to use a semi-automatic mixture setting process. There is a map where you enter the target mixture in every RPM and Load cell, then run the engine through the load cell range. The program uses the wide band O2 sensor to generate a correction map to your current tuning map. The correction map values can be reviewed by the operator and if all looks good, update the base tuning map. A few times through that and you should have an accurate base map. You can then run open loop, or go to a closed loop operation for close mixture control over a wider range of conditions such as air temp & pressure.

The semi-auto tune part just doesn't work. Whether it's software, or firmware, I don't know. There is a bewildering number of settings for setting the closed loop O2 sensor operation and generation of the correction map. I spent hours at it, asked questions on the DTA forum, asked the manufacturer, all without any resolution. I finally gave up. From the DTA web forum, it's obvious that many users also are unable to get the closed loop correction map part to work, although a few do. Useful support from DTA directly does not exist.

Other than that, it works fine. The hardware seems robust, but the control software needs help. Several P8Pro users have petitioned DTA to release enough information so a 3rd party could improve the software, but they have refused.

DTA has a later model ECU, the S60. That unit appears to be a lot better in both software features and it's ability to used closed loop tuning. It does not do some things I wanted such as sequential injection and distributorless ignition for an 8 cyl engine. DTA is soon to release an S80 which should do all those things for 8 or more cylinder engine. At this time, the P8Pro appears to be a useful orphan without much chance for fixing some warts. The unwillingness of the DTA company to either fix the P8Pro problems itself to the point of it fulfilling it's own advertising claims, or releasing information so someone else can, makes me reluctant to recomend their newer products.

I'd like to try a couple other ECU's, but lack of $$ and time gets in the way. The new Wolf system looks good as does the Autronics. The Motec is considered the gold standard of ECUs, and it might be. The M48 works well and has been proven. I don't like Motec's policy of requiring more $$ for features you realize you need that the basic unit won't do until unlocked by $$. The last I saw, the M48 software was DOS and not at all easy to use.

Megasquirt is coming along nicely too.

BC

Thats for all that info Louie. Thats great. There is always the race box of the AEM Pro unit, but that is only installable by a shop that takes a class, and will install it themselves. Maybe thats not that hard to get into that situation, but it seems limiting. There is a very active forum for users of the AEM units.

Megasquirt is moving along very well indeed. I still have a MSnE unit in a box in my garage ready for...something.

I still think a Map based Cop or CNP system with sequential is the best way, but many of these systems do very well with wasted spark and batch fire.

Louie928

Yes, I don't like to buy something and then not be in total control of it as the AEM would be. So far, I'm very pleased with the wasted spark ignition system. The wasted spark firing during the exhaust stroke is supposed to help with igniting normally unburned hydrocarbons going out the exhaust, but I don't actually know how effective that is. Before the Cayenne COP unit, I didn't like having to have a separate coil driver for each plug and the number of the high current pulse wires running around. The larger GM style almost COP didn't appeal either. I did want the cleaner look of a single plug wire to the basic plug connector at the cam cover. Odd how technology changes come along to alter everything even before you have your project completed. Today, I'd probably go with the Cayenne COP where you could keep it neat with smaller wires with less chance for noise leakage from the higher current driver wires, and only need to feed each COP unit with a 5 volt pulse plus power source and ground. I'm not extremely convinced that sequential injection is any better than batch fire. It's supposed to be a little smoother with less pollution at idle and low throttle operation. The DTA allows you to change the crank angle at which the injection pulse starts or ends. This is adjustable while the engine is running. I cannot tell any difference in idle no matter where the injection pulse, of about 3ms, is positioned throughout the entire 720 degrees of crank rotation. Sequential injection does allow me to not have any fuel pressure dampeners such as the stock 928 has. That may be the only real advantage. I just have the basic adjustable fuel pressure regulator.

I should mention that the DTA, in addition to some quirks, does have 3D maps where you can click and drag the intersection points to change values. The 3D presentation allows you to better see discontinuities in the map and helps you make adjustments to fill in approximate values of cells that you may not have tuned directly. The cold start map, air temp and pressure compensation, throttle movement enrichment, idle speed regulator, auxiliary input/outputs all work as they should. I didn't try the automatic launch, flat foot shifting, and traction control systems.

BC

Do understand that the AEM would not be locked. They can't do that. You could do your own tuning, and I installed and played around with the AEM Pro Software, and its very good, if not "drop down menu" crazy.