640 WHP 7 litre 928!

[Barbapapa]

Originally Posted by BrendanC

Hey Mike. Awesome stuff.

Those are cayenne coils? How are they?

Hi B'.
I couldn't use the Cayenne coils with the Motec IEX. It's an issue with the Motec, it sends a super long dwell time during cranking and the Cayenne coils shut down upon seeing 20ms. I even sent one to Motec for bench testing but there's no fix.
I'm using Bosch coils as used in BMW Grand Am cars. They fit nicely, I found a couple of o-ring sizes that when slipped over the body allow them to be inserted in the 928 heads like a regular plug wire.
It's too bad about the Cayenne coils because I spent alot of time sourcing the oddball terminals. I do have a set of coils and connector parts to sell for cheap!

[Barbapapa]

Originally Posted by icemang17

Mike
I did blow a rod bearing back in April...got really lucky since I caught it early enough to save the motor.....did LOTS of mods to improve oiling, just about everything you can short of a drysump like yours....(which looks great BTW)

Taylor cross drilled crank
"loose" rod bearings .0025" or looser
3/8th pan spacer + windage tray
GTS baffle
Improved breather routed to catch can (two on both sides)
new oil cooler in bumper, not radiator
Accusump with 55-60psi EPC valve with switch to prevent idle oil dump

Nooo! But you did so many good things! Did that crank get oil from a grooved thrust bearing?

BTW, I'm mounting my oil cooler now. Do you have any ideas? I was wondering about not putting it full face in front of the radiator so as not to hurt water temps. Is that a valid concern?

BTW2. Nice driving in that video! That one long turn looked tricky to master, you would wind up hitting the apex just right.

[jorj7]

Very nice numbers and great looking motor. Congrats on a labor of love.

[Louie928]

Originally Posted by icemang17

Mike
Amazing work.....especially making a BIGGER displacement engine that makes less torque down low then some "convential" strokers....a great way to save the driveline... I did a little dyno comparsion between yours and Louies 603whp run....its interesting that Louies motor makes considerably more torque below 5500rpm....but yours make more past 6k, as Louies is dropping past 5500rpm.....

So looking at the torque curve comparsion....it must be a combo of the cams-larger valves and probably shorter ITB runners that shifted the torque curve so much higher....

So what size diameter ITB and how long of a runner? My guess is 52mm+ and maybe 6 inches

Brian,
Some of my posted numbers are in STD corrected, not SAE. The last runs I did at home was 611 STD / 591 SAE corrected at 6500. That's with alcohol injection too. I believe the torque was right at 500 lb ft with SAE correction. The dyno run here at the OCIC meet in Dallas was 595 RWHP (with alcohol) at around 6500. The peak torque numbers here were way off on the high side so not reliable. I'll check the numbers when I get home.

[rhjames]

Originally Posted by Barbapapa

BTW, I'm mounting my oil cooler now. Do you have any ideas? I was wondering about not putting it full face in front of the radiator so as not to hurt water temps. Is that a valid concern?

I can't say what your particular class restrictions are concerning cooler placements, but if I was doing a race-only car, mine would be located in the rear passenger area with fans and ducting from naca window ducts (Nascar, Grand AM, etc)....both engine oil cooler and transaxle cooler as well. this eliminates concerns of blocking air flow and adding additional heat to the radiator/underhood area. if you were running a blower or turbos (I know you're not, but you could in some venues), you could also put the intercooler in the passenger seat area inside an icebox, similar to the one pictured below:


like I said, I don't know what your class allows, just a thought---

--Russ

[icemang17]

Mike
I blew the engine BEFORE the mods....when I smoked the bearing I was running a 100% stock S4 oiling system....no mods at all, well other than amsoil....looking back I should have done all this stuff 1st....such is life....

On the oil cooler...since my racer has NO foglights we cut out the back of the foglight well in the bumper and mounted the cooler on the passenger side behind the foglight, slightly low...so it is not in front of the radiator.....I didn't want something that hot in FRONT of the radiator....plenty of room in there since the headlights are gone and welded over...

I went with a 19 row Setrab cooler....it should be plenty...& we bypassed the in radiator cooler completely.....I hope this makes for cooler oil & water!!

Hmm with your beast already a NASA race vehicle......it would be easy for you to enter the 25 hours of Thunderhill???? The race shop I use to store-transport my 928 won the 25 last year in spec miata class..... a GTS4 or GTS 5 races in ES class...which is the 2nd fastest behind ESR...but isn't really that fast with only a 2:00 lap...which your car could do restricted easy..probably 1:56....but a 12 gallon fuel cell won't work....I figure 20 gallons an hour for your machine minimum....

[Larry Herman]

Very nice work. 2 quick questions about your motor, if I may:

1) I assume that the reversion that you mentioned is eliminated due to the extremely short intake runners?

2) What are the holes in the cylinder sleeves for?

[BrendanC]

Originally Posted by Barbapapa

Hi B'.
I couldn't use the Cayenne coils with the Motec IEX. It's an issue with the Motec, it sends a super long dwell time during cranking and the Cayenne coils shut down upon seeing 20ms. I even sent one to Motec for bench testing but there's no fix.
I'm using Bosch coils as used in BMW Grand Am cars. They fit nicely, I found a couple of o-ring sizes that when slipped over the body allow them to be inserted in the 928 heads like a regular plug wire.
It's too bad about the Cayenne coils because I spent alot of time sourcing the oddball terminals. I do have a set of coils and connector parts to sell for cheap!

So did I. Todd and I have spoken for possibly hours on end about these coils. I am one of the first (with a few other's help of course) to get all the part numbers, and put together what is needed.

Upon further review, Todd (and I secondarily) have found out that the Cayenne coils are great - EXCEPT when you go too long on the dwell, OR (and this may be a big issue) if the falling signal has ANY noise at all. As in one nano-width size bobble on the down side of the 5v dwell signal.

The Coils, in these cases, or just the latter, seem to start to multi-spark. Obviously bad. Very bad infact, if it sparks something that was not to be sparked.

The concern was valid enough for Todd that he has veered away from the cayenne coils to the LS2 truck coils, which (ironically) are BETTER and MORE expensive than the Cayenne coils. They are 20 dollars compared to the 12-14 for the Porsche coils, and they can take huge amounts of dwell time - lastly - they do not seem at all to be very sensitive to the falling edge noise on the 5V signal that Todd and I believe may be inevitable in an open-world use cycle. Meaning - we have no idea if that 5V signal could get noise from simple things like driving under a high tension wire, etc.

I have not given up on their use as of yet, at least on the second engine - the 4V engine where they would fit perfectly. I always planned on using the LS2 truck coils on the 2V anyway.


Mike - Does your motec system give the 5V signal - I guess I would have to assume that it does? Do you have the part numbers for the coils? How did you source them?

[Barbapapa]

Originally Posted by Larry Herman

Very nice work. 2 quick questions about your motor, if I may:

1) I assume that the reversion that you mentioned is eliminated due to the extremely short intake runners?

2) What are the holes in the cylinder sleeves for?

Larry, the reversion issue is eliminated for part throttle operation because there's a big throttle blade right there. The overall length of the intake tract isn't important. A typical ITB engine has the throttles almost completely closed during most cruising, more so with a big engine. Both the proximity of the throttle to the valves and the very fact that there's one for each cylinder are factors.

If you have 2 different engines with ample valve duration, one with ITBs and one without, the ITBs will have a smoother idle without the lope and light throttle driveability will be better.

The holes in the sleeves are to allow coolant to flow freely.

[Barbapapa]

Originally Posted by BrendanC

we have no idea if that 5V signal could get noise from simple things like driving under a high tension wire, etc.

Mike - Does your motec system give the 5V signal - I guess I would have to assume that it does? Do you have the part numbers for the coils? How did you source them?

That's surprising that noise was an issue. A Cayenne itself must be a noisy environment anyway with all the on board Latte machines and foot massagers.

Are you sure about the input signal you're giving it?
Motec has one I donated and they were impressed with it aside from intentionally shutting down at exactly 20ms. I don't think they supply it a 5v signal but rather a ground signal. It will probably fire with nearly any kind of activity. I'm over my head about that, it would be nice to hear from a boffin like Alan. I have a hunch you should not see the problems you saw and it's related to your wiring.

[Larry Herman]

Thanks for the explanations. That is what I understood about the ITBs.

As far as the coolant holes, again I thought so but I didn't see any relief in the heads to allow all of the holes to flow. It seemed like some of them would be blocked, if that really matters. Then again, it very well could be in the head gasket itself.

[Barbapapa]

Originally Posted by Larry Herman

As far as the coolant holes, again I thought so but I didn't see any relief in the heads to allow all of the holes to flow.

That area with the holes is below the deck surface, the holes just allow coolant to surround the top part of the cylinder. They're not super important.

[BrendanC]

Originally Posted by Barbapapa

That's surprising that noise was an issue. A Cayenne itself must be a noisy environment anyway with all the on board Latte machines and foot massagers.

Are you sure about the input signal you're giving it?
Motec has one I donated and they were impressed with it aside from intentionally shutting down at exactly 20ms. I don't think they supply it a 5v signal but rather a ground signal. It will probably fire with nearly any kind of activity. I'm over my head about that, it would be nice to hear from a boffin like Alan. I have a hunch you should not see the problems you saw and it's related to your wiring.

I have not wired one up yet. They are still in the boxes I bought them in more than a year ago. They were tested by AEM though, and it was relayed through Todd to me what they said. They are of course 4 wire, Power, Power ground, Signal, Signal Ground. I was only aware of the units taking a 5V dwell signal.

[rhjames]

Originally Posted by Larry Herman

Thanks for the explanations. That is what I understood about the ITBs.

As far as the coolant holes, again I thought so but I didn't see any relief in the heads to allow all of the holes to flow. It seemed like some of them would be blocked, if that really matters. Then again, it very well could be in the head gasket itself.

Originally Posted by Barbapapa

That area with the holes is below the deck surface, the holes just allow coolant to surround the top part of the cylinder. They're not super important.

looks like a Darton MID sleeve.

--Russ

[lizard928s]

Mike,

I sent you a PM on here, I am interested in your Cayenne units.

:cheers:

[928forlife]

I just want to say - amazing!

[Herman A]

Originally Posted by Barbapapa

Larry, the reversion issue is eliminated for part throttle operation because there's a big throttle blade right there. The overall length of the intake tract isn't important. A typical ITB engine has the throttles almost completely closed during most cruising, more so with a big engine. Both the proximity of the throttle to the valves and the very fact that there's one for each cylinder are factors. The holes in the sleeves are to allow coolant to flow freely.

Your engine modification is really an impressive piece of engineering and nice craftsmanship.

I have two questions re the principle designs which you have choosen.

Does the distance from the intake valve seat to the throttle affect reverse flow, performance, eficciency or anything else, under the assumption that the throat of the inlet tract is situated far away from the throttle?

Why did you choose the indirect TPS+MAP way of measuring the air flow instead of using one or two MAFs for direct air mass measurement into the plenum chamber, which is already part of your design? The first method doesn't cause any pressure drop in the intake system but a properly dimensioned MAF should give neglible. Isn't it very difficult to measure the over one cycle, hugely variable pressure, which fluctuations depends on the throttle angle and rpm?

[Cassera]

what do you think the 0-60 mph will be or the quarter mile speed

[Danglerb]

Originally Posted by Cassera

what do you think the 0-60 mph will be or the quarter mile speed

Traction limited.

With big enough tires to hook up, half shaft limited.

My guess, around 4 sec 0-60, and around 135 to 140 mph.

I'd love to see what it really does on a track though, should be soon?

[rhjames]

Originally Posted by Herman A

Your engine modification is really an impressive piece of engineering and nice craftsmanship.

I have two questions re the principle designs which you have choosen.

Does the distance from the intake valve seat to the throttle affect reverse flow, performance, eficciency or anything else, under the assumption that the throat of the inlet tract is situated far away from the throttle?

Why did you choose the indirect TPS+MAP way of measuring the air flow instead of using one or two MAFs for direct air mass measurement into the plenum chamber, which is already part of your design? The first method doesn't cause any pressure drop in the intake system but a properly dimensioned MAF should give neglible. Isn't it very difficult to measure the over one cycle, hugely variable pressure, which fluctuations depends on the throttle angle and rpm?

I suspect the ITB set up is more easily constructed as opposed to MAF with single large throttle body and sheet metal intake manifold----and then there's that Helmholtz theory to deal with.....

although Mike has demonstrated fabrication of stuff is no big deal for him!!!

--Russ