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Supermodel Dynoed! Long Update.

 
Old 04-18-2005, 01:07 AM
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Seth W
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Default Supermodel Dynoed! Long Update.

Well, my car finally made it to the dyno.

The first thing I have to say, is thanks to Tom, Marc and Bill.

Tom came over to dyno my car during the course of some very serious family issues. I hope me and the GT were a "good distraction" for him. I am indebted to him. Tom, let me know how I can repay the favor (and no, I'm not selling my car for 10K).

Marc gave freely of his time today and his expertise. He (and Susan and Julie Ann) did this 4 days after having a newborn. This is above the call of duty, on the part of all three. The little "potato" (their words, not mine) is a beauty. She will be getting her first street legal porsche in 2021--while it will cost 150 to fill the tank, at least the family can wrench together. Thanks, thanks thanks.

Bill got me to the goal line. Again, many hours and lots of effort. This is a selfless and wise person (don't tell him I said that). I was glad to scare the crap out of him during his brief co-pilot time--he scared me before. thanks!

Ok, now that I have thanked the academy. . . .

The great news: 410 HP at 5.7psi in 3rd gear. First gear is silly, second gear with LSD and 285 in the rear hooks up nice. This is a fast freaking car now. neck snapping. Driving around town is just about normal, with very slight "sucking" sound? coming from the SC. its cool. The belt slipped slightly, I'm not worried about that boost number, its PLENTY. I'll up it later once all is worked out. It looks great the polishing is so nice and will only get better as Andy finishes his fuel rail addition. I had a big stupid smile on my face the whole time. What a blast. I'm gonna eat 911 turbos and poop out boxsters.

The good news: Bill's throttle cable is working quite nicely, and it continues to progress. throttle response and feel is stock. A great innovation. Idle is 85% of stock. No hunting whatsoever (thanks again to bill) but a slightly more rough feeling. An acceptable trade-off for more than a 100 ponies and I think this is likely to improve.

The challenges: (1) The bolt for the air pump rubs on the belt. The answer is, I think, a smaller bolt head or a smaller pulley (talking less than 1 mm needed here). We are looking for a bolt that will fit and will solve this problem. (2) The belts are "walking" on the pullies. PS, air both moved 1/2 way off the pulley after about 10 dyno pulls. Marc thinks the answer is to space out air pump and ps pulley slightly so that this can be cured. He is going to fabricate a spacer. (3) throttle tip in and boost is hard. in my car, under less than full throttle in higher gears this led to significant pinging. I understand Jim's car did this too. Under full boost in lower gears (better in 3rd, not quite good but better in 4th) this was less pronounced. Other than never lugging it--the answer lies (according to Marc) in either a gradual boost build up (something andy is already working on IIRC via a bleeder valve) or a RRFPR. I would rather be less aggressive with boost rather than throw fuel at the problem.

So next steps are that Marc is going to sync up the belts, find a bolt and then we are in business. I'll be waiting to see what Andy develops next in way of bleeder valve etc. so I wont be doing any slight throttle in 5th gear action.

I'm hoping to make my car a showcase for this kit and am looking forward to Andy's continued effort and support. He has certainly invested a massive amount of time and energy into this kit and as it progresses I look forward to working out the kinks, posting huge HP numbers and being able to drive it with the same kind of reliabilty I have enjoyed up to now. I (and more importantly Marc) believe the fundamentals are all there. Its not a peice of cake, but the potential upside is huge and the more work done the better this will get.

There is a TON more I could post on the whole thing, but this was long enough already--I'll let you all know how it goes--but leaving the country for 10 days on thurs.

Seth
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Old 04-18-2005, 01:22 AM
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mspiegle
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Good to hear your car is on the road. There must be something funky about the ignition timing with the GTs... the GTS doesn't seem to have the same tip-in problem. Chris had mentioned that he would get a slight ping when the car was in stock form, but it doesn't seem to exist anymore. I guess i'll know more once I get my tuning kit hooked up and put the car back on the dyno.
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Old 04-18-2005, 01:31 AM
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Great report! I'm glad you're able to finally drive the car to see what you've wrought . . . And have fun at the Autodromo Enzo e Dino Ferrari! Take some pics and stay safe during the track invasion when Schumacher wins his first race of the season.
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Old 04-18-2005, 01:35 AM
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Very good job guys. Thank you Seth and thanks to everyone that helped me/Seth. There are some truly dedicated 928 community members at DEVEK and revolving around there. It sounds like there will soon be one more, little 'tater.
410RWHP on 5.7psi is awsome, and that is with no tuning! I assume unless you guys did something I didn't know about.
Smog belt: I had originally specified a 3 rib belt v/s a 4 rib. Some people used 4 ribbed belts and all reported successs so I switched to 4 rib because they are easier to find for replacement. The goodyear part # is 4030385. I'll find one and send it out. This along with a smaller diameter bolt such as an allen head should fix the rub.
Powersteering: When the belt streches it loosens and this tends to allow it to walk off. This belt proabably just needs to be tightened.
I specify for all belts to be re-tightened and the crank belt to be re-torqued at 500mi. Possibly 100 mi will be better.
The ping for both GTs was a first. Not the S4, 85, 86 or GTS has done this. I have the valve ready to test. It sux that both you and Jim (Crashed Supermodel RIP awaiting resurection) only have bad 91 octane or it wouldn't be a worry and you may enjoy more power.
I would really like to see the fuel/boost/power curve charts ASAP.\

WTG Guys!
Andy K
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Old 04-18-2005, 01:38 AM
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Well, I think I'll congratulate Marc and Susan first - for their new staff edition. I had no idea it had already happened - are there any official photos of the "potato"? (BTW: That's what I called the 928 after I saw it for the first time on the streets of Stuttgart)

And Seth: Congratulations to you, too! Those are pretty impressive numbers. I'm glad you are getting something in return for 'neglecting' your family during the process. Will I need a helmet when you give me a ride at Sharks in the Park?
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Old 04-18-2005, 01:40 AM
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Tony
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410Rwhp out of the blocks! Your well on your way.
Post a pic of the whole set up on the car. All Ive seen is just the polished blower

What a blast. I'm gonna eat 911 turbos and poop out boxsters.
yyyup, stock up on TP!


BE CAREFUL.

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Old 04-18-2005, 02:11 AM
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BE CAREFUL.
Seriously true. No injuries, no blown engines to date (knocking on wood). Keep it safe, keep it fun!

Andy K
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Old 04-18-2005, 02:34 AM
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Bill Ball
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Note that the 410 wasn't even 5.7 lbs! The belt was slipping, as by the time the car got above 5K RPM the boost was less than 5 lbs and falling. We didn't have time to tighten and do another run. So, this thing is a monster! The post-dyno ride was brief but effective. Burned Seth's big rubber all the way through first gear and into second. No chance to test 3rd - too many kids around the ice cream truck.

The power steering belt that walked was very tight, but I agree that should be the explanation. My PS belt walked one groove but after re-positioning and making sure it was tight, it has not walked. Seth's had walked halfway off the pulley before it was noticed. I repositioned it and tightened it.

The Allen head bolt is a good idea for the smog pump bracket. This is a very long bolt, but that would be a good answer as well as the 3 rib belt or a small spacer behind the pulley and allow the 4 rib belt to be one groove further out on the crank pulley - there is room for that if the PS pulley can be spaced similarly. Should work.

The tip in was interesting. Pinged like an SOB on partial throttle against a load, and the chart showed it very lean. Putting the hammer down w/o any part throttle and the mixture stayed rich enough so there was no ping. So the WOT switched not being tripped combined with lower fuel pressure at low boost made for lean conditions. Hammer the sucker and there did not seem to be a problem. BTW, it was a cool day.

It will be fun to see what this does on 6.8 lbs after we tighten that belt!
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Old 04-18-2005, 02:43 AM
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Note that the 410 wasn't even 5.7 lbs! The belt was slipping, as by the time the car got above 5K RPM the boost was less than 5 lbs and falling. We didn't have time to tighten and do another run. So, this thing is a monster! The post-dyno ride was brief but effective. Burned Seth's big rubber all the way through first gear and into second. No chance to test 3rd - too many kids around the ice cream truck.
Amazing! Goodyear specifies some very short period after running the belt for their belt to be re-tightened, something ike 15 minutes of use. I guess this is especially true of the SC belt since it sees much greater force than the other belts. And truly so when it is dynoed within 1hr of it's install. One more thing for the directions.

Andy k
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Old 04-18-2005, 03:27 AM
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Tony
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Originally Posted by Bill Ball
The tip in was interesting. Pinged like an SOB on partial throttle against a load, and the chart showed it very lean. Putting the hammer down w/o any part throttle and the mixture stayed rich enough so there was no ping. So the WOT switched not being tripped combined with lower fuel pressure at low boost made for lean conditions. Hammer the sucker and there did not seem to be a problem. BTW, it was a cool day.

It will be fun to see what this does on 6.8 lbs after we tighten that belt!

Ive had the same thing happen and i seem to be able to tune it out or at least alter its onset with my Adjustbale fuel pressure regulator. Im using 24lb injectors and at 40psi i would get the leaning...chucked it up to 50psi and it dissipated but my idle was now faster.
I havent had any pinging but i see it going lean on my ARM 1 and Widebad. Its easy to induce. Just slowly roll on the trottle with out producing boost and it will slide lean. It seems to take a sec or two for the LH to figure it out before it "snaps" out of the situation and the ARM1 starts hunting again as it normaly would. While the ARM1 is an indicator of sorts, it wont tell you specifically where your at.

It seems that we are operating in that area where there isnt boost being made but the SC is still chucking a bit of air in there and it takes a sec for the LH to compensate with what ever fuel pressure/delivery it has to work with??.

15-16:1 partial throttle roll on is what i see. Like you said Bill, the second i "floor it" from that point, the problem goes away. Foot to the floor from a stop, no issues. We'll se when it gets hot here.

Im heading to Dariens in the AM, ill log some stop and go as usual driving.

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Old 04-18-2005, 03:31 AM
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Seperate comment.
I assume it is specifically the cams in the GT that make for this power difference from an S4?

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Old 04-18-2005, 04:17 AM
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Originally Posted by Tony
Seperate comment.
I assume it is specifically the cams in the GT that make for this power difference from an S4?

Isn't it higher compression too? Also, Seth has an IC.
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Old 04-18-2005, 04:29 AM
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I think the 85/86 uses 10.1, the GTS has 10.4, but the GT and S4 are both 10.0

What's up with the knock sensors? Do they not retard enough to be effective? I guess i'll find out soon...
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Old 04-18-2005, 04:43 AM
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S2's are 10.4-1 as well...but we can't supercharge these yet. Knock sensors have only so much effectiveness. It surprises me that the later cars with knock sensing have problems with knock- it must be the fuel curve.

N!
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Old 04-18-2005, 07:20 AM
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[QUOTE=GoRideSno .......The ping for both GTs was a first. Not the S4, 85, 86 or GTS has done this. I have the valve ready to test. It sux that both you and Jim (Crashed Supermodel RIP awaiting resurection) only have bad 91 octane or it wouldn't be a worry and you may enjoy more power.

Andy K[/QUOTE]

Andy,
Would a regular S4 EZK ( or the chip from one) perform better with a SC'd GT?
I installed a GT EZX in my S4 to take advantage of the more agressive ignition advance - perhaps the reverse may benefit the pre-ignition observed, if the ping is due to the GT curve.
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