john gill

THe extruder honing is a marginal gain at best , I was not totally happy with the job that was done and given the testing that I have done the stock manifold used with GT or other modified cams , with the early high compression pistons refitted into the later engine releases a lot more of the torque and then tuned with aftermarket ecu , which gives you complete control of the mapping and modern control . This results in a very strong package .
This should be able to be achieved for less than $5K if you are handy with a spanner. Even the stock GT exhaust is not to restrictive , if you afford a larger bore exhaust all the better. One of the things that I have seen is that the old cats are normally buggered and quite restrictive along with lots of the sensors .
FOr the best gains from stock make sure all the sensors on the engines are within working specification . When I first began experimenting on the dyno , one of the areas that encouraged me was that I needed to change the engine loom . I had DC reluctor stop working , after investigating I found that even though the wiring looked ok from the outside , the wiring inside the sheathing was rotten , now my GT has not done a lot of Ks and is in good condition , when you install a high end ecu it normally includes a new loom.

At this engine speed detonation is very destructive as it happens a lot quicker and the onset cannot be heard by the ear, I have headphones connected through specific software to listen for the onset , actually as I have previously outlined whilst tuning you can watch the torque build with the advancing ignition. For those of you that relay on the stock ecu to manage your knock dont , I have seen detonation happening before the ecu can react to it , very interesting to watch .
Oh I originally built this engine with the view to spin it past 7000 rpm ,but as tested with the package of components that I used after 6400 the torque is in free fall so there is no point abusing it past this point , this is the ability to be able to test . The shift alarm is set to 6500 , with the flat change set to bounce of 4600 (clutch in ) very interesting experience when going flat out .

Tuomo I hope that I have answered your questions , I am happy to share my experiences with the community .

john gill

No need to apologies Jim , I have been on a steep learning curve the last 2 years , I placed the other graphs in there as a reference . the GT runs to 5000 rpm are only ones that I have on file , My previous dyno had a chronic failure and the whole unit was replaced , with the result that graphs that I would like to post i donot have , but if you look at point to point reference , you can get the idea.
THe s4 is an auto , the development stages lists the mod from one to the next stage.

Kevin Johnson

Hi John,

Thank you for using the full crank scraper and windage tray set up. In the kit there are two full length scrapers and one 3/4 length scraper (downstroke).

I have some suggestions for people using the spacer kits which should incrementally improve the breather situation and oil conditions over the sump.

When I designed the kit one of the constraints was not to require other engine mods. If people are willing to make mods then more is possible.

The 3/8" spacer brings the engine closer to the original design proposed by at least one engineer at Porsche in the ubiquitous, never-bothered-to-be-measured-before, technical drawing found in the other thread (it is .475mm shy in thickness with respect to the additional 10mm thickness of the bedplate/girdle/block-cradle; original design 90mm thick versus production 80mm thick). The additional 20mm sump depth found in the very early 1977 production pans would obviously be highly desireable. Perhaps Erkka can provide a part number.

The needed mods would be four M12 main studs that extend a minimum of 10mm further toward the sump, 3/8" spacers for the oil pump brackets and tube bracket mount.

You would then need to section the "T" shaped scraper and windage tray base so that the windage tray tunnel and support remains complete. The sump cover and trap doors would then be able to drop down and and keep the G-rating of the wetsump intact (by virtue of the shift of the pickup tube opening).

If you are willing to do this I would be willing to send you some parts: a modified "T" upper section with mounting studs for the sump cover (this is actually also a windage tray) and a second modified "T" part with the original full length scraper intact plus a down stroke scraper section which will make that a full length scraper. Colin has an example of this in his kit for a dry sump. In between these two sections you would need to place spacers. I have some hardened steel M12 washers that are 2.5mm thick -- three plus an additional ~2mm 14G "T" section should do the trick.

Please let me know.

One side note: When I designed the kit the working assumption was that the normal running oil level should be just below the factory sump cover/baffle/windage-tray. I found this level in the 928 to be about 6 quarts.

This working assumption is followed in the vast majority of engines that I have examined. One example in which it was not followed was the Porsche designed V6 that Ford was using. They massively overfilled it. My suspicion is that they were concerned about running afoul of some car owners that never check their oil levels. So they included a nice quart or two buffer over the original design. I note that the Ford engine was the subject of three SAE papers investigating issues with air entrainment. Might this have been the underlying reason why? Hmmmm.

john gill

Hello Kevin

Always interested in other ideas , but sorry I am a bit thick I do not reallly follow what you mean, as I have mentioned in another thread , I was staggered by what amount of oil is pumped out of these engines, once you surpass 6000 rpm, as I originally built this engine to be strong to 7000 rpm, any of your additional ideas welcome.

Kevin Johnson

Hi John,

I will make the pieces and show some pics. A picture is worth a thousand words.

Read the history of the Corvette engine developed by Lotus Engineering. The blocks share some similar architecture. This engine also had a reputation for expelling oil during development.

john gill

Thanks Kevin

Has anyone ever thought to knife edge the stock cranks, I do not know the ramifications of this, but I am sure that someone here explain the whys and why not .

ptuomov

Bull nosing and knife edging a crankshaft is expensive. The benefit is also not demonstrated, although so many people are doing it that I am sure that there is some commonly perceived benefit from it. Caveat lector.

Some interesting comments from a pro on the S4/GT and GTS crankshafts:
http://speedtalk.com/forum/viewtopic...10406&start=75

Hayk928

Hi John,

cool job! How difficult was it to fit the Adaptronic 1280? Could you use the OEM loom and sensors? Did you install any additional sensors? What about injectors / MAF / Ingintion - I'd be interested what's exactly required to replace the factory ECU.

About the grooved crank bearings: Are they OEM or did you get something custom?

Thank you very much and keep going on!

Best

Marc

john gill

Hello Mark

Completely new loom and used the stock sensors ,but renewed them , installed a tps switch . THe car runs Map sensing , completly removed and replaces the old MAF .

The bearings were new , but I had them grooved .

Kevin Johnson

http://www.circletrack.com/techartic...ce_cranks.html

Vizard does some careful dyno testing of aero (bullnose) crankshafts versus flatface as well as crankshaft coatings. Well worth reading.

john gill

Thanks Kevin

Great read

Hayk928

Thanks John

I'd like to have a closer look on that set up, cuz I think, the plenty old 8-bit ECU easily becomes the typical bottleneck on a tuned shark engine after all mechanical stuff is updated.

Cheers

Marc