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Old 04-17-2005, 03:32 AM   #1
reddevil
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1990 Legacy wagon
goes 12.387 @ 116.5

Default The Supercharged NA is pushing 10 psi finally........

but it has been a long time in coming. I must have 70-80 hours now working on the stepper pulley setup, with two complete failures until this last attempt. I finally mounted the stepper pulley by boring a center hole large enough to press fit a timing belt idler into it, and bolting this to where the power steering pump used to be. I had some annoying belt slip issues, and still do to some degree, but I am now sure i can overcome the last of them.

I was also having some boost leak and I think my recirculating BOV was leaking so I removed it so now i just plain dont have a BOV.

But I had a rather depressing evening with it though. I took it to the drag strip for some runs. Last week, on 7 psi and bad clutch, I was consistantly getting 15.2-15.4 at 88-89 mph. I expected to do at least this. Nope, my best was 15.6 ONCE, with an average of 16 sec. The damn wagon just felt freaking boggy. You would lean forward in anticipation of the boost surge and end up just leaning forward. Occasionally, and infrequently to boot, the engine would just suddenly have alot more power, but this seemed random.

This was before I removed BOV. The PSI would start at about 9 and just leak down to about 5. I was sad. I figured it could be bad gas and/or combined with that gallon of Xylene I through in, or the parisitic loss of the supercharger, combined with the boost leak, was just eating up the power.

So i called it an early night and drove back to the shop to stare at the engine and have a beer or two.

This is where I decided to remove the BOV. Since the belt seemed pretty damn tight, I decided to forgo building a new tensioner as I just didnt have time to do that tonight.

I was so tempted to go back to the 7psi pulley setup but while I was thinking about this, I wondered if the spark plug switch I did when I installed the stepper pulley may be to blame for the bogginess.

Well I stuck the stock plugs back in (I had stuck 1 step colder plugs in), but most importantly, the Magnecor wires seemed once again to not be on the plugs correctly. So I stuck some "old" new wires on and off I went for a test drive.

Other than some belt slip that now only allows the PSI to fall to about 7 (sometimes) I suddenly have a powerful engine now. Spark plugs and spark plug wires just seem to have a say in all of this I suspect.

It was too late to head back out to the drag strip but I am pretty damn confident I would be hitting a 15.0 if not better now that the engine actaully is firing correctly. and this with a clutch that cant take a 3000 rpm lauch and you have to take your time shifting or the clutch with slip. It has some serious pull now, probably about 240 chp, 190 whp. At 7 psi it was 152 whp but this was with a clogged tank fuel filter and firing on a bad plug wire. It also has some serious need for 94-95 octane gas with this high of boost and compression ratio.


My next goal? (after fixing the belt slip of course) is to get a 13.99. Nitrous of course.
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Old 04-17-2005, 09:33 PM   #2
Teh Legacy
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Congrats! It's great to hear that you're still spearheading this and making progress. Keep it up!
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Old 04-18-2005, 07:34 PM   #3
BREWPUBEAVER
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still schweet
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Old 04-19-2005, 02:06 AM   #4
reddevil
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But tonight I put it back to the 7 psi. The stepper pulley setup just have too many problems that money (ie lack of) could not fix. The belt slipped, the boost wobbled, the engined detonated, the power was way less than the 7 psi setup. It just didnt seem to work that well, even thought the boost guage was definately 10 psi straight up.

Basically, I suspect that I was/am suffering the dreaded parisitic loss of the SC when using the stepper pulley. When I get the money, I will eventually just get a bigger crank pulley made that will give me 10 psi and I suspect that I will not have any of the above problems. Anyone want to buy a stepper pulley?!
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Old 04-19-2005, 02:17 PM   #5
MadMax
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Got any pics of the stepper pulley?

I've come to the same conclusion. I got two new pulleys one that is 2.75 which happened to match the stock pulley i had, i guess i should have measured better, and a 2.25. The 2.75 now with the improved groves will hold boost to redline in every gear, right around 7 psi.

The 2.25, even with a smaller belt and tensioned pretty hard, slips like crazy. I cant keep constant boost and it usually falls down to about 3 or so psi. In 5th gear it hits 10psi. I think its just too small to prevent slipping. So i'll have to get a stock rs crank pulley and hack it up to make it a little bit bigger and keep the 2.75 pulley on to increase boost.

In any case, I know im already very close to the recommended limit for the s/c, under 14000 rpm. To get more power out of it will require over revving the rpm, which I probably wont do as the extra boost isnt worth the extra wear, higher temps and hp draw needed to push the s/c rpm to those limits.

By the way, what is the size of your current pulley both on the sc and crank? Im testing out some formulas and want to see how close they are to your dyno'd numbers.

Thnks,
MM
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Old 04-19-2005, 02:58 PM   #6
reddevil
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The crank pulley is 7.25 diameter, the supercharger pulley is 3.625 diameter. The stepper pulley is 2.625 for the small section and 3.375 for the outer section.

So I went from a 2-1 pulley ratio to a 2.5-1 pulley ratio. When it did work, it raised the average psi from 7 to 10. I'll attempt a picture tonight.
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Old 04-19-2005, 03:23 PM   #7
MadMax
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Im guessing your around 240ish hp at the crank. Your prob pushing out 8.8 psi but with your ic and some belt slip,it's showing up at around 7 psi.

we might be at the limit of the eaton m62, i know at 2.5 ratio your over the limit by like 3K. At this point I might mod the engine to make better use of the boost, or change out the eaton for a twinscrew setup

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Old 04-19-2005, 03:59 PM   #8
reddevil
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I did a mustang dyno run and put down 152 at the wheels, but this was with a clogged fuel sock (when replaced, fuel pressure jumped 10 psi) and with a questionable 1-3 spark plug connections. I would guestimate at least 160 at the wheels when running well. If I were losing 25% due to drivetrain loss, then I am getting about 215 at the crank. Remember I am a 2.2.
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Old 04-20-2005, 03:07 AM   #9
reddevil
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Well, drove it around today a few times since changing it back last night. Wow. So much better. Even off boost it drives much better. And this must plain and simple mean that the stepper pulley setup was sapping power.

It runs so well with the stock NA ecu I am still convinced that I can run higher boost (9-11 psi) with few serious modifications, if at all. I am just going to have to do it via larger crank pulley. All the time I have spent trying to up the boost via the stepper pulley is just wasted depressing time, oh my god, so much wasted time. I suspect that I could have made $400 in 80 hours , but thats just negative thinking.

Other than aluminium welding, I could turn my own large pulleys if needed, but since I can't weld aluminium, it is easier to pay the crazy machinist to to do all the work. Genieus and crazy often go together.

The most depressing/craziest thing about this stepper pulley maddness is that the first time I managed to get it to work, it really did. I was pushing 10-12 psi, no slip, no lag, no power sap. It worked, I swear. It was incredible. Kind of like a drug. I guess thats why I have been willing to spend all this freaking time on trying to do it again. Damn power addiction!
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Old 04-20-2005, 02:21 PM   #10
MadMax
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Haha i hear yah, i've spent 220 on new custom pulleys to get more boost. One is too small and the other is the same size as the original pulley. Oh well.

Also i think with mods ive done to the exhaust side, the engine flows much better. i really got to get it to a dyno soon. So far with the new pulley which has better groves that grip the belt, the car runs awesome, feels so stock its nuts. I also fixed the tubing running to the bypass valve, it use to suck its self into a thin line, so i put a custom peice of metal tubing in there to prevent the vacuum from sucking it skinny. I hope my gas mileage will improve now that it can breath so much better off boost.

Now i need custom gears so i can really make use of the torque down low Unfort all the info on gears and whatnot is bout turbos. Its cool being pioneers in a different direction, but it also costs much time and $$$. But hey thats the price we pay to be different.

MadMax
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