john gill

Hello All
Here is my story of the evolution and development of my GT, of which I love, I currently await the arrival of CJ s new camshafts , to see what can be achieved from this package. Although thus far I have been more than pleased with the result, even with the amount of time it has taken .
If you follow this link http://www.emtec.net.au/928GT_engine.html to the page on my website it has all the details .

ptuomov

Cool page and engine.

What's your view on the absolute benefit and the benefit per $ from each of these mods? (I've added questions in clarifying questions in parentheses)

- ported throttle body increased 2 mm
- ported heads with 968 intake valves
- Elgin reground camshaft (which profiles?)
- extruder honed manifold (intake or exhaust? I am guessing intake since you've got headers)
- 944 turbo connecting rods (these are basically the same as the '87 powder forged rods, right?)
- balanced assembly
- 180 degree ceramic coated mandrel bent headers and custom exhaust
- early pistons flat topped giving 11.6 static compression
- ceramic coated ports and piston crowns, cylinder crowns
- stock vs. JDS modified vs. Adaptronic 1280 engine management

RyanPerrella

thanks for posting this info looks like a fun read later

mark kibort

This thread is.........

mark kibort

worthless without........

mark kibort

DYNO RUNS!

Great read on the link. guess all that modification went to 341 rwhp. pretty nice, but we have seen 335rwhp with no mods at all. You would think the compression bump alone with the 85 pistons could account for all that differential gain. Then again, similar mods as you have done went up to 375rwhp with dennis' motor.

That windage screen scares the ..... out of me. watch your oil pressure, if it dips even a little from 5 bar, pull the pan and carve out some BIG holes in it.

have fun. looks great.

I hope SOMEONE does a dyno run for that CF intake that is like Anderson's and Fan's. I think that is the holly grail for our S4 motors.

mk

mark kibort

Is your starter oriented wrong, because my terminals face downward and that seems to have the starter positioned quite a bit higher than yours. I would be hitting the starter if I had mine oriented that way.

I love those headers! kind of reminiscent of the corvette long tube headers.

Hilton

Look on the left side of the page he linked to.. there's dyno runs there including stock GT for baseline.

No point comparing numbers to other dyno's in other countries unless the dyno's are calibrated to a common standard (I think only Dyno-Dynamics do this?). Especially if one set of numbers are from a Dyno-Jet

john gill

I have my own dyno and workshop , the best bang for the buck is to boost , so the engine makes its best power before the early 6K engine speed.
After this the oil control issues become extreme , even with the mods that I have done I was staggered by the oil that is thrown around and out by this engine once the engine speed exceeds 6K .
Mine will spin happily past the 7K mark , but its torque is in free fall ,so there is no gain to be made , by sppinning it any more , also the oil is being pumped out of the sump , even with DR s oil catch system , I actually blew 1 of his supplied rubber plugs , through the lines to be caught in the catch tank.
I underwent this project because I like the stock look and the sound of a natural aspirated engine under full power. THe sound of this thing under full noise is orgasmic, when I get a bit more time I will post this sound up on the website. It will be interesting when the CJ camshafts arrive and are tested .
If you were to engage someone to perform this work for you, it would be prohibiitvely expensive. I have access to lots of secound hand bits ,so I could mix and match,and call in favours, and as have the dyno I could also test .
The stock ecu I have found does not have the finite fuel control after 6k and as this needs to be an area whereby detonation control needs to be tightly controlled to maintain good torque, it became a lay down miseah , to go to an aftermarket system ,which comes with the addition of all the modern features of current ecus , and 100 % control of the mapping . [/I]

Dan87951

Did you use factory alusil bores?

john gill

yes used a surplus GT block , no boring or finishing needed , all the compression varies from 232 - 236 PSI .

Dan87951

Wow, impressive! Do you have any detonation issues? Is this a pump gas engine?

john gill

98 pump gas , I am **** about detonation , with the dyno when you accurately tune you can see the torque climb and peak , as your advance the ignition , as this map is based and tuned for this fuel , if I was to put a lower octane fuel in I would have to remap , as I can switch to another map if I want .

ptuomov

I get the boost part and the some of the oil control stuff.

I am mostly interested in where do you think the best absolute bang and the best bang per buck is in terms of air flow and combustion.

For example, is there a gain from extrude honing the intake manifold? The legend is that people who have tried it have not seen gains.

Also, is the stock throttle body a significant restriction under 400 hp? Assuming WOT, of course! ;-)

Do the 180-degree headers beat the regular 4-1 headers on a dyno?

Since you own a dyno and have been working on this stuff for a couple of years, I am very curious to find what have you learned about the benefits of these individual mods.

Why is detonation control critical after 6000 rpm if the natural volumetric efficiency drops like a rock after 6000 rpm?

Bill Ball

Hi John:

My understanding of engine performance is pretty basic. And my ability to interpret dyno charts is primitive. So, naturally, I got real confused by your charts and stages.

The torque range changed down to 460 Nm or so in some of the charts. ??

Why do your baseline GT runs only go to 5000 RPM?

I had a hard time figuring out the change in results from baseline to stage 1 and then stage 2. Can you summarize?

I don't understand the GT to S4 chart. Which "stage" GT is this? The upper curves looks like your stage 2 GT. The lower power curves look like your baseline GT curves. Which one is S4? Is this a 5-speed S4?

Sorry to be so ignorant.