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Old 09-22-2007, 01:38 PM   #1
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Default Yep, stock clutch can't hold 12psi...

Tonights the last night for drag racing and likely one of the last times I get to drive my car until next summer, so I decided to try for 12psi. With just the 1.8 injectors/walbro/begi fpr, I was touching 9's AFR, so I tried to lean it out to low 11's. (Any leaner and my fabricator will yell at me.) The clutch isn't slipping so bad that I stop accelerating, but I lose boost at higher rpms. It drops off quickly to like 5 or 6psi and then builds up again. I don't know what rpm it drops because I am watching boost/the road, but I think it is around 6.5k. When it holds 12psi in second gear, I lose traction, which is fun. 12PSi in 3rd is fun too, while it lasts. Do you guys think I will be faster with a little clutch slip or should I turn down the boost again and try to minimize it?
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Yep, stock clutch can't hold 12psi...-sept07.jpg  
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Old 09-22-2007, 01:44 PM   #2
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Originally Posted by rotaryjunky View Post
Tonights the last night for drag racing and likely one of the last times I get to drive my car until next summer, so I decided to try for 12psi. With just the 1.8 injectors/walbro/begi fpr, I was touching 9's AFR, so I tried to lean it out to low 11's. (Any leaner and my fabricator will yell at me.) The clutch isn't slipping so bad that I stop accelerating, but I lose boost at higher rpms. It drops off quickly to like 5 or 6psi and then builds up again. I don't know what rpm it drops because I am watching boost/the road, but I think it is around 6.5k. When it holds 12psi in second gear, I lose traction, which is fun. 12PSi in 3rd is fun too, while it lasts. Do you guys think I will be faster with a little clutch slip or should I turn down the boost again and try to minimize it?
I would turn the boost down until you get another clutch, dont wanna **** that clutch up and hardly be able to drive do you? I've been there done that its not fun, just dial down the boost until you can get a stronger clutch
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Old 09-22-2007, 02:22 PM   #3
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We can always trailer it home, worst case. So that's not a huge deal. At least it would keep my wife from driving it to work (and forcing me to drain the 87).

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Old 09-22-2007, 03:16 PM   #4
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We can always trailer it home, worst case. So that's not a huge deal. At least it would keep my wife from driving it to work (and forcing me to drain the 87).
True, but if you plan on driving it very much on the street, i would wait, if u dont care about having to trailer it home and not have it until after a clutch swap, and having to get your flywheel resurfaced and ****, then keep it at 12
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Old 09-22-2007, 03:18 PM   #5
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I coudl have told you that.
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Old 09-22-2007, 03:42 PM   #6
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What about for tonight? I am thinking of trying 10psi as a compromise. Or should I stay at 8psi and hope for zero slip again?
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Old 09-22-2007, 03:57 PM   #7
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How are you changing your boost level? Wastegate spring?
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Old 09-22-2007, 04:03 PM   #8
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Mbc.
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Old 09-22-2007, 04:08 PM   #9
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I don't understand. If you're drag-racing, I assume you're at WOT. If that's the case, then once your clutch starts to slip, I don't see you getting it back halfway through the gear unless you're torque drops off so low at high RPM's you do get it back. If that's the case, then you're probably running stupid rich up top and would be better off developing your tune AND a new clutch.

If you're clutch is slipping, lower the boost until it doesn't. Continued roasting of your clutch by massive slipping at high boost will overheat the clutch and might cause it to fail completely.

Just spend the $350 on an ACT XT and be done with it. You gotta pay to play.

Also, if you're going to run 12psi, I highly recommend an injector upgrade to 305/310 so you can run less fuel pressure.
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Old 09-22-2007, 06:10 PM   #10
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Originally Posted by samnavy View Post
I don't understand. If you're drag-racing, I assume you're at WOT. If that's the case, then once your clutch starts to slip, I don't see you getting it back halfway through the gear unless you're torque drops off so low at high RPM's you do get it back. If that's the case, then you're probably running stupid rich up top and would be better off developing your tune AND a new clutch.

If you're clutch is slipping, lower the boost until it doesn't. Continued roasting of your clutch by massive slipping at high boost will overheat the clutch and might cause it to fail completely.

Just spend the $350 on an ACT XT and be done with it. You gotta pay to play.

Also, if you're going to run 12psi, I highly recommend an injector upgrade to 305/310 so you can run less fuel pressure.
I am running rich, but take a look at my AFR log in the first post and tell me if I am in the stupid category. I'm honestly asking, I am not being sarcastic.

I would rather that my clutch fail than just replace it, its more fun that way.

I am definitely going with the ACT and a torsen (still waiting on my parts car deal with crazy lady) this winter when its on stands for six or more months.

I am probably going to just run 10psi and then go EMS. This 12psi idea was just for tonight. I still might go 305, because I am blowing out O'rings on my injectors!
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Old 09-22-2007, 07:01 PM   #11
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WOW! I didn't even see the graph first time around... in fact, you're stupid lean... 14.5 through the midrange will definitely kill your engine. I can't believe you're not knocking like crazy. You need a lot more fuel... and definitely time for 305's.

What octane fuel are you running?
Do you have a fuel pressure gauge???
Are you using the boost-line restrictor that Begi provides with their AFPR?
How far in do you have the needle turned on your AFPR?

You can fuel 12psi on 1.8's, but you're gonna need somewhere between 110-130psi of fuel through the midrange. 305's will bring that down to 90-100psi. Your top-end fuel looks fine, but that's only because you're so lean overall.

Blowing injector O-rings is a fire waiting to happen.

PS: Your Nordlocks are shipped!

Your clutch will fail if you keep drag racing and putting mad slip on it... but it just as easily could fail on the street while you're trying to merge into traffic. Better to turn down the boost for awhile until you get more fuel, and then replace the clutch before you do turn it up.
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Old 09-22-2007, 07:31 PM   #12
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Gotta go, but I will let you guys know what happens...
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Old 09-22-2007, 07:33 PM   #13
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You are stupid rich uptop and stupid lean in the middle that sucks
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Old 09-22-2007, 07:45 PM   #14
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probably too late but my stock clutch holds at 11.9psi but my car weighs under 2000 lbs.
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Old 09-22-2007, 08:24 PM   #15
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Quote:
Originally Posted by rotaryjunky View Post
...I was touching 9's AFR, so I tried to lean it out to low 11's. (Any leaner and my fabricator will yell at me.)
And that's why you don'y listen to your fabricator when it comes to tuning:gay:
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Old 09-23-2007, 01:49 AM   #16
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Originally Posted by samnavy View Post

What octane fuel are you running?
Do you have a fuel pressure gauge???
Are you using the boost-line restrictor that Begi provides with their AFPR?
How far in do you have the needle turned on your AFPR?

Blowing injector O-rings is a fire waiting to happen.

Your clutch will fail if you keep drag racing and putting mad slip on it... but it just as easily could fail on the street while you're trying to merge into traffic. Better to turn down the boost for awhile until you get more fuel, and then replace the clutch before you do turn it up.
- 93 octane
- I have a fuel pressure gauge that I should extend under the wipers for testing.
- Yes, I am using the restrictor.
- Needle is now (see graph) about one turn open from closed.
- I installed new O rings with the 1.8 injs but two failed quickly, so I replaced all of them with my original O rings and no further problems.
- We don't have traffic here. No on ramps either.

Tonight went fine, ran a 9.5 @ 79mph (2.39 60 foot, this has to go) but mostly it was just fun watching other people blow motors. I know, my day will come. I kept it at 9psi and the clutch seemed fine. But I am going MS. Wife got a job this week selling copiers and its going well. I am also going to do an extreme budget turbo on the B16a civic so I can blow it up instead. The biggest issue with the clutch is the break in because of zero time and I would like a new clutch. Probably better for now anyways because of less stress on the vlsd. I might try 8psi on BF drag radials in two weeks if I can get them cheap enough. Anybody want to buy a full size copier?
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Yep, stock clutch can't hold 12psi...-9psiafr.jpg  
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Old 09-23-2007, 11:13 AM   #17
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I also think you're in dire need of an O2 clamp... lots for sale in the classfieds... will smooth out your AF during transition into boost a lot and probably run you a little richer through the midrange.
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Old 09-23-2007, 11:28 AM   #18
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easy fix.

step 1: increase base pressure with the center adjuster until you're 12.5:1 or so in the mid
step 2: add 2nd high flow check valve to needle valve exit--I got one from Autozone or other chain parts store that had a built in T. There's a write up here if you search for it.

you should be able to enter boost at around 12.5:1 and get richer to about 11.5:1 at redline this way
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Old 09-23-2007, 11:39 AM   #19
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Quote:
Originally Posted by samnavy View Post
I also think you're in dire need of an O2 clamp... lots for sale in the classfieds... will smooth out your AF during transition into boost a lot and probably run you a little richer through the midrange.
I have one, should I adjust it?

You guys rock. I have been meaning to do the 2nd one way, but I seem to forget everything. Do you have any idea what 0 psi fuel pressure I should aim for?

I have actually reached my original goal, I beat a Solstice GXP. And his times were consistant and his launches looked great. ([email protected]) MS would really be for longevity and drivability, although I really think drivability is remarkable for an FMU, thanks to the AFM.
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Old 10-06-2007, 01:28 PM   #20
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I haven't done the 2nd one way valve yet or increased the base pressure because autozone was out of them and I haven't had any time, but I did turn down the boost.

How is this temporarily?
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Yep, stock clutch can't hold 12psi...-afrratio.jpg  
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