goodspeed928

KILLER JOB!

Chuck Schreiber

Thanks Greg for clarifying,

Again, very nice job!!

slate blue

Well got the car started for the first time in months, apart from the 3" system it also has a new engine. All the wear parts were replaced except for cams and the block. It was lapped and in fact it was a new one from Porsche not that long ago.

So what does it sound like. It has lost that V8 burble at 2000 + rpm, that is unfortunate, at idle it sounds great. However it is a little lumpy, why lumpy,mmmm, well I can only put it down to large headers, (1 3/4") and the custom intake runners which are shorter and the ported heads allowing more reversion at idle.

It isn't too loud in the garage but that isn't under load. It is very very noise when revved hard. So it will be real loud when under hard acceleration. I'll see if I can live with it. As to the slightly lumpy idle, again I'll see if I can live with it.

I would like to get it tested for noise before I weld in the by pass valve, I also need to raise the exhaust up a touch on one side at the rear. It was a massive job building that exhaust, I think I'm happy with it, I will try to get to the dyno in the next two weeks.

Cheers Greg

928SS

IT LIVES!!! congrats!!!

slate blue

So the old design, a little bit hard to fit when fitting as a four pipe assembly, need to undo the left hand side engine mount, the new design has a lot more clearance everywhere it was tight. So now both sides can be fitted without undoing mounts and are easy to fit. No power will be gained by this mod.



New design before re-coating


You can see how the no.6 pipe now tucks in behind no.8


New and used pipe with the new design, time consuming having to chip the coating off.


I call these block huggers, that's original isn't it! All pipes were again back purged with argon and trial welds fused nicely leaving a smooth bead.


This is the other side, all pipes are around 28" long and are +/- 1/2" of that number which is pretty good, Pipe diameter is 1 3/4" for the primary pipes.

Ducman82

Very VERY well done

Strosek Ultra

Very good job done, Greg. Thinking of your sore back I am even more impressed.
Åke

hopwood

What kind of power are you seeing and what is the rest of the engine / exhaust config?

I run a Euro S2 4.7 high compression motor fed by a CIS/KJet injection system. I use a set of 86.5 "shorty headers" feeding a custom-made 2.25" y-pipe that feeds into a 3" single pipe system with a front, mid and rear silencer.

The pipe into the rear silencer has a flange so it can be removed and replaced with an RMB or indeed something quieter.

When I started out with the restrictive 79/4.5 single pipe system I was making 256bhp but boat loads of torque. With the 86.5 manifolds and the new system I'm at 320bhp/320ft-lb exactly.

Joel

Koenig-Specials 928

Note to self: I must learn how to weld.

Wow!. That looks awesome. Great job.

Giovanni

My name is Giovanni and I approve this message

z driver 88t

True craftsmanship. I am constantly amazed at the talent on this forum. Great job!

slate blue

Hi Joel,

Given you are in the UK I guess that your numbers are from a Dyno Dynamics dyno? Also in the UK they tend to convert back to flywheel HP, so again I guess those are flywheel numbers?

My numbers are rear wheel numbers in "shootout" mode, with standard cams and the CIS intake runners modified to fit the S2 injection system. These runners and the plenum have been ported. The engine has been carefully assembled, by that i mean lots of little detail but with regards to the intake I used to look through the opposite runners and line them up with the ported plenum.

You may be surprised at how far they may be out. Likewise I did the same with the headers, I made notes about how I would push each pipe against the studs to get pipes to line up well with the ports. Something you can do with individual pipes. We are not talking about much but if there is a lip at any of these runners by even 1 mm and in the case of the intake they can be more than this you will effect the flow by causing turbulence.

The engine has a new bore and blowby is extremely small, piston to bore is just under 1 thou. and the pistons have a positive deck height of 0.25 mm. So we did 305 rwhp on the same day another 928 did 228 rwhp it also had a new bore but it was only 98 mm bore not 100 mm. On another dyno day it went up against a auto GTS with X-pipe and this 5.0 was 50 rwhp stronger.

The thing is this engine runs out of puff once it reaches 5000 rpm, it makes over 300 rwhp at that speed. I recently went back to look at the head flow numbers and with the cams it has I suspect peak flow is around 220 cfm. This gives a max potential HP of approx 450 HP. To convert my rwhp numbers back to flywheel numbers we end up just under 400, I would be relaxed about 390 HP. (When it was a 4.7 L it made around 350 HP.)

So the guy who does my heads now also believes we are struggling with the heads and the flow can be increased to at least 240 cfm with standard lift cams or 250 cfm with my new but unused for many years 0.500" lift cams. That is by using the Porsche 48 mm intake valve.

The cylinder head porter's work is something to be seen, his work looks like it has been done by a CNC, he has various high tech tools and software, his flow bench is not the standard 10" or 28" but the larger 60" model.

If the engine can be made to breath it could do around 430 to 450 HP. We will check the new custom manifold on the flow bench with it bolted to the head. It also uses current tech 4 spray hole injectors.

Anyway, your exhaust is too small, it will be restrictive and you don't have cylinder tuning potential with shorty headers. To give you an idea of a sizing that works well with these sized engines. The primaries 1 3/4" into 2.5" collectors and X-pipe. Then the system expands out to 3" which as you see in the page one pics is duel. All mufflers are straight through. I am going to have to put a rear muffler on now and delete the valve as that has been outlawed here now. It wasn't too loud mind you but without the valve it would be. A OEM muffler will be sectioned gutted and 3" stainless pipes fitted.

slate blue

Hi Joel,

I would add you have made major improvements over stock, the CIS system can be extremely accurate with the air fuel ratio. You may get extra power by porting the manifold and heads but the major improvements from where you are not that easy to achieve, a lot of hard work and expense for minor gains I am thinking. I think I would be happy with your setup unless you sell it and go for something bigger in capacity.

I think I may do that to use up my surplus parts that have gathered much dust. I am able to achieve an engine that is 5.4 litre and use my custom 52 mm intake valves along with my bigger hydraulic cams, 236/221 duration with higher lifts at 0.500" and 0.470" respectively.

I also have an extremely advanced ECU from your part of the world too, the OBR Euro 8, it has a lot of built in logging capacity 16 mb and it will be interesting to log some of the 928s oddities like oil pressure.

slate blue

Pieces of a new puzzle.



A box full of fun, many different bends with various radii. These are stepped tri-y headers that start at 1 3/4" then to 1 7/8" then 2" first set of collectors then 2 1/4" and then the final set of collectors which will terminate at 3" The pipe wall is thin and varies between 0.7 mm and 0.9 mm. Anybody got some spare argon?

Hilton

I've got spare argon/co2/o2 mix for MIG'ing steel - altho' I suspect you want pure argon for TIG? (I bought my own cylinder outright - from speedgas, so no rental)