Pops' 1997 S6 - 07k BLK WDW

[prj]

I usually run 0.82 a/r 3071's at 29 taper 26.
This turbo looks more to be 3076 sized, try running closer to36 taper 32, but watch IAT's and listen for det, to find where the hotside and coldside limits are.

You should easily make a lot more tq that way... and some more power also.

Of course first the clutch needs sorting, and relay the pump if you haven't yet.
I am surprised the clutch is letting go at only 500-ish WTQ though, it really should not. Was it bedded in properly?

[loxxrider]

You do realize he is running on pump gas right? Pump just will not support 36 psi. Meth may allow it though.

[prj]

You do realize he is running on pump gas right? Pump just will not support 36 psi. Meth may allow it though.

It will if your CR is low enough
Talking about boost alone without context is not very good also, all depends on cylinder filling.
If you had an engine with a very high VE, then yes.

A 3076 on an engine with stock head, stock cams and stock CR stops making power at 31 PSI.
An engine with a 8.3 CR easily makes more power until 36 PSI. An engine with 8.0 CR on stock head keeps making power until about 39 PSI, but EGT's get nasty due to late timing.

Talking 98 RON, so 93 AKI. On 95 RON / 91 AKI the thresholds will be lower.

[loxxrider]

The CR argument is a great point. I'd love to see 36 psi on pump with that CR, but I'd be truly amazed if I saw it. I'd hate to run 8.3:1 off boost though.

[prj]

The CR argument is a great point. I'd love to see 36 psi on pump with that CR, but I'd be truly amazed if I saw it. I'd hate to run 8.3:1 off boost though.

Transient response is better everywhere down to around 8.0:1, if you dyno-tune your timing map.
I have a car with about 8.3 here with slightly increased displacement + stock head and it is much better off boost than a car with stock CR. It also spools faster because you can almost run MBT down low.
I would not worry about drivability until you get to 8.0 and below.

Fuel efficiency suffers on light load cruise, but only on light load cruise.
If you dyno tune these cars, you will see just how knock limited they are.

P.S.
I am not pulling those numbers randomly, BTDT after mapping close to 70 of these engines :wink:

[EDIGREG]

This turbo looks more to be 3076 sized

wut? This turbo is a CT3-6465...that's like 37R sized !

Needz moar corn juice

[Hank]

37r may be a bit of a stretch, but it is definately closer to 3582r size!!

[Jamo]

64mm billet is bigger than Gt35r lol gt3076r sized, the turbo is 750 bhp rated although it doesn't mean this setup will make that though

For comparission the 60mm comp turbo Kai has just dyno'd made 706 hk 841nm at 2.3 bar

[loxxrider]

The CR argument is a great point. I'd love to see 36 psi on pump with that CR, but I'd be truly amazed if I saw it. I'd hate to run 8.3:1 off boost though.

Transient response is better everywhere down to around 8.0:1, if you dyno-tune your timing map.
I have a car with about 8.3 here with slightly increased displacement + stock head and it is much better off boost than a car with stock CR. It also spools faster because you can almost run MBT down low.
I would not worry about drivability until you get to 8.0 and below.

Fuel efficiency suffers on light load cruise, but only on light load cruise.
If you dyno tune these cars, you will see just how knock limited they are.

P.S.
I am not pulling those numbers randomly, BTDT after mapping close to 70 of these engines :wink:

So you are saying that because you can advance timing so much, the lowered compression is a moot point? In that case, you'd imagine fuel efficiency wouldn't be affected much either since you can lean it out more with more timing advance...

I'm not arguing with you by the way. I am just voicing my hesitancy towards your points. I would love to have the dyno experience with this particular application. Who are you by the way? I figure I/we should know who you are if you have that kind of experience with this engine.

[prj]

This turbo looks more to be 3076 sized

wut? This turbo is a CT3-6465...that's like 37R sized !

Yeah, sorry, just looked at the specs now.
I didn't actually read them, just looked at the dyno graphs a bit. Realized now it's using a quick spool valve, so that's why it comes on boost as early as it does.
Yeah, in that case needs way more boost than it's running now... Still wonder why the clutch failed though.
Out of all the cars I've mapped, one has been CT. The rest have been Garrett, KKK and Holset, so I don't have a lot of experience with CT.

So you are saying that because you can advance timing so much, the lowered compression is a moot point?

Correct, when you are loading the engine.

In that case, you'd imagine fuel efficiency wouldn't be affected much either since you can lean it out more with more timing advance...

No, because where most fuel efficiency "occurs" is on light load cruise. That is not knock-limited, so dropping compression there will lose efficiency. So overall fuel efficiency will drop. But the moment you give it more than like 20-30 deg throttle, you're already laughing, so power wise, unless you go real low on the CR you won't feel a thing. The car feels really awesome at 8.3:1 on transient response off boost.
But of course you have to re-tune the entire ignition map on the dyno to knock limited MBT.

I'm not arguing with you by the way. I am just voicing my hesitancy towards your points. I would love to have the dyno experience with this particular application. Who are you by the way? I figure I/we should know who you are if you have that kind of experience with this engine.

http://www.s2forum.com/forum/member.php?u=9612
I believe we have had some postings in the same thread before
I just never posted on mg before, only lurking.

[chaloux]

Some good discussion up there!

Hm. So what's the compression ratio of this now that it's been stroked/bored (92.8/83mm)? I believe the pistons we got from 034 were for 8.5:1 compression, but I'll have to confirm that with dad. I never really thought about this before... stock is 9:1?

Maybe that's why we were able to advance so much on the dyno with Brady. I specifically remember him saying, while tuning timing, "huh, that's weird. More timing yeilded no more gain" - and we did this like 3 times beyond without any knock. So then we went a degree back before the gain stopped.

[chaloux]

Oh, and PRJ - the clutch was rated for about 550 crank. Brady's dyno is very conservative, with an X rate somewhere around .25. Dad's car was right on the limit with 26psi - at 29psi is when it started slipping.

[EDIGREG]

If everything else remained the same, it is 8.5:1. If significant material was taken off the head when it was decked then it will be a bit higher. Stock is 9.3:1

[loxxrider]

http://www.s2forum.com/forum/member.php?u=9612
I believe we have had some postings in the same thread before
I just never posted on mg before, only lurking.

Ah yes, I haven't had much time to check out S2forum in quite a while. I do recognize the name from there however. That and the fact that you are from Estonia makes me trust your opinion much more. Your English is so good I didn't realize you are from that area. Some seriously fast cars out that way We need more of this kind of influence on this forum! Please do stay around. I'd like to ask you your opinion on an engine build for my car.

[chaloux]

Just spoke with dad. He said either 8.5:1 or 8.3:1. And he thought that the head gasket may be compression dropping as well, but I have a feeling it is stock comp. The block was decked a tiny amount, it was pretty much perfect, just needed a fresh surface. That makes so much sense and explains so many things... initial spool, advance of itming, no knock whatsoever, etc. Duh!

If I would have known that I probably would have pushed for more boost on the dyno. I just didn't even realize that 8.5:1 wasn't stock. Never occured to me.

Sweet. So that means mo' powa!

[chaloux]

Clutch came today. Still waiting for the flywheel but the pressure plate is certainly beefier than with the DMF. The clutch disc is a 4 puck unit. Tiny, really. Pretty cool that it holds that monster tq.

[bradyzq]

Just spoke with dad. He said either 8.5:1 or 8.3:1. And he thought that the head gasket may be compression dropping as well, but I have a feeling it is stock comp. The block was decked a tiny amount, it was pretty much perfect, just needed a fresh surface. That makes so much sense and explains so many things... initial spool, advance of itming, no knock whatsoever, etc. Duh!

If I would have known that I probably would have pushed for more boost on the dyno. I just didn't even realize that 8.5:1 wasn't stock. Never occured to me.

Sweet. So that means mo' powa!

Mo POWAH! indeed.

You just provided a wonderful example of why feedback from the dyno (and the sexy knock listening device) is pretty much all you need. Had we been going by convention, we would have left a bunch of timing and torque on the table. I got slammed on another forum for "doing what the dyno tells me," but your car shows that it works!

There are so many variables at work here, including compression ratio. The work you have done on the cylinder head may also have a positive effect on knock resistance.

BTW, were those 8.3 or 8.5:1 pistons taking into account that your engine is a stroker? AAaaand, did you actually measure? Apparently, the advertised expected compression ratio for a set of pistons may differ from the actual.

[chaloux]

I was planning on emailing you one of these days Brady, you beat me to it. I don't think we measured everything with the pistons, but everything we did measure was correct. I'll have to look and see what measurements we need to calculate CR and see if we can figure it out without taking the motor apart.

So I expect we'll be able to hit 30psi pretty safely, then. Of course we'll see, but that's what I expect. Dad is working on ordering the AEM FAILSAFE device so once it all gets hooked up we'll stop by again Brady

Another note - aren't 4 puck discs pretty hard on stuff/pretty grabby? Hopefully Marc can confirm that this is indeed the clutch disc we want.

[loxxrider]

I got slammed on another forum for "doing what the dyno tells me," but your car shows that it works!

Seriously? Doing what the dyno tells me is always what I learned was the right thing to do when it comes to timing...

[bradyzq]

I got slammed on another forum for "doing what the dyno tells me," but your car shows that it works!

Seriously? Doing what the dyno tells me is always what I learned was the right thing to do when it comes to timing...

Yup, seriously. Just one guy, and one piler-on.

It's what I learned too, and it works.

[chaloux]

Marc meant to send a full face disc. Good thing the car isn't up on the hoist waiting! Too many other side projects going on right now.

[Marc]

I got slammed on another forum for "doing what the dyno tells me," but your car shows that it works!

Seriously? Doing what the dyno tells me is always what I learned was the right thing to do when it comes to timing...

Yup, seriously. Just one guy, and one piler-on.

It's what I learned too, and it works.

The poster probably meant that you will likely hit det before max torque which is probably true. In all other cases though it's absolutely the right thing to listen to your Dyno regarding adding or pulling timing if showing gains or losses in torque respectively.

[Marc]

Marc meant to send a full face disc. Good thing the car isn't up on the hoist waiting! Too many other side projects going on right now.

Sorry bout' that!

[chaloux]

Marc meant to send a full face disc. Good thing the car isn't up on the hoist waiting! Too many other side projects going on right now.

Sorry bout' that!

No problem Marc, just glad I checked first.

[bradyzq]

[quote="bradyzq"] I got slammed on another forum for "doing what the dyno tells me," but your car shows that it works!

Seriously? Doing what the dyno tells me is always what I learned was the right thing to do when it comes to timing...

Yup, seriously. Just one guy, and one piler-on.

It's what I learned too, and it works.

The poster probably meant that you will likely hit det before max torque which is probably true. In all other cases though it's absolutely the right thing to listen to your Dyno regarding adding or pulling timing if showing gains or losses in torque respectively.[/quote]

Nah, you're giving the guy way too much credit. We weren't even at the point of talking about MBT. He was effectively trolling.