I believe there was a post recently (last 3 months) where someone found a new vendor for 9 bolt gears and it was pretty cheap compared to 9bolt.com prices, maybe try a search on that one (I think the thread involved 3.73 gears but they had more choices than that).

I dont have enough experience racing at the 1/4 to add anything in those regards, but reading about your tune kind of caught my attention. You might have some more HP in your combo that you aren't seeing because of the tune. If you haven't done so already you might want to consider a trip to a local dyno where they hook up the WB02 and you can do a few pulls and adjust some of the stuff in between pulls (fuel pressure, etc) to see the different results. Not so much to see how much power you make but to try and fine tune the AFR. The Vortech FMU does its job but unfortunately you aren't able to really fine tune it like stand alone or 730/749 w/ $58 code. So you probably wont be able to fully tune the car perfect, but you might end up getting some extra power from trying to fine tune the AFR. For the datalogging thing I would say go with WinALDL since its still a 165 ECM car. The WinALDL program is free, the ALDL cable can be made for cheap, if you've got access to a laptop w/ a serial port then you're set.

 

jnkcltr:

Every time you post, I realize how much I need to get some more info on what is really going on in my engine/turbo system before I try to push it any faster. My plan was to do that this week, but with the gears the way they are, we'll have to wait until I get a new set in. Interesting on the fuel injector calculations. The 1/4mile HP calculators seem to figure high for my combo, indicating 370-440hp at the wheels. I did have it dynoed two years ago at the Wilwood cruise in hot/sticky air and it put 328hp/467tq to the wheels. I think I can scan injector PW,on my scan tool, and then use that to calculate DC%.

The Plan as of now:
1)Replace rear gears and set them up right this time (I have another used set lined up)
2)Install another O2 bung to do some real WB testing (I have an Innovate LM1, but I have considered permanently installing the AEM UEGO gauge)
3)Install open IAT sensor, log IAT PID with scan tool while driving
4)Use scan tool to retrieve other data, such as injector PW and knoick retard, etc.
5)Evaluate data, do adjustments if needed

CrazyHawaiian:

Thanks for the tip on the 9-bolt gears. I'll have to search for that. ANd I do have a laptop with a serial port. So, if my scanner can't do what I need it to, I'll probably try using that program.

 

CrazyHawaiian:

Is this the thread you were talking about:
https://www.thirdgen.org/forums/tran...ight=9bolt.com

I think I'm going to try another used gearset for now, but I'm interested in finding a good supplier for future reference. I was trying for a while now to get a mini spool from 9bolt.com, but he never got back to me. My 3-year old GM posi is doing quite well for me as of now, I think it is actually tighter now than right when I first installed it (I can't overpower it by hand like some of the Eaton Posi's I've installed).

 

I am kind of biased on the tuning thing because that is why I went the turbo route on my car. Be warned, you could waste a lot of time messing with the tune for little HP gains. I am running all GM parts except for the cam so I need to tune it well to get every last bit out of the GM parts.

Your dyno RWHP is inline more with what the injector calcs HP that I did. Since your ignition is good, I would be tempted to give it a little more fuel (fuel pressure) at boosted WOT.

Logging data at 160 baud with WinALDL will pretty much be a waste of time. You will get about 15 engine samples of data in a 1/4 mile run. Use TunerPro v4.13 and you can get 50 times that amount using the 8192 baud rate in a 1/4 mile run. Your 1989 ECM does (or should) support the 8192 ALDL rate ($6E mask).

You can build or buy an ALDL cable. Check out the DIY PROM board or Google search for the schematic or vendors. Building it yourself would cost less than $20 complete with Radio Shack parts. A good "commercial" cable costs $50+ the last time I checked (years ago). If you have a laptop computer with a serial port and Windows 98 or higher then it is any easy setup.........ALDL cable with TunerPro v4.13 (the ALDL log file is included with it). Once you log data, you won't do any engine changes with out it. You can sit back with and replay a run / drive and watch the engine data to see what was actually going on. It also gives you a reference of how things got better or worse with mechanical or ECM changes.

EDIT: If you have an old MS-DOS laptop, you can still ALDL log at 8192 baud using ECM852. It is an old MS-DOS program that works great. Both ECM852 and TunerPro 4.13 can export the engine data to an MS-Excel spreadsheet so you can look at stuff graphically.

 

Here's the thread I was talking about earlier, I checked into it again and it seems they only have 3.70 gears listed (but they are CHEAP!). Maybe if you call Motive you can get info on other gearsets they might have available.

https://www.thirdgen.org/forums/tran...ghlight=motive

About the tuning thing, no doubt something like TunerPro is better. I brought up WinALDL because its really easy to setup and use when you first get into DIY stuff w/ the laptop. Maybe a waste of time for an experienced tuner, but also maybe a good building block for someone just getting into it. I dunno how much 89JYturbo has messed around with that stuff, but I know it was a good tool for me in the beginning.

 

Thanks again for the gear link.

I hav enever done any type of ECM tuning. Turning screws on a secondary injector driver is as deep as I've been. My scan tool can do WAY more than 15 samples in a drag strip pass. If I narrow it down to just the PIDs I'm interested in, the numbers read so fast you can't follow them. The graph feature become essential when you only have 4 or so PIDs.

jnkcltr:
I'll see what the WB shows before I turn any screws I'm anxious to see what I can learn.

 

Another quick update:

Just figured I should let you all know I won't be able to make it to Cecil on 5-27 like I said earlier. I have a used set of 3.27 gears to install, and I'm also going to have a heavier driveshaft made up at a local shop (the stock aluminum one worries me, plus it has above .040" runout). While I'm in there, I'll build a driveshaft loop that will bolt unto the torue arm (I don't feel like removing the carpet agian to bolt one into the floor).

Once the driveline is back together, then I'll be doing the testing over Memroial Day weekend. We'll see if we can discover any other corks in the system before playing with the manifold pressure....

 

I don’t think that you have to defend yourself there, but I would argue that your defense is really up to interpretation… I took my ’97 WS6 to the track on the 4th day that I owned it and as I pulled into the staging lanes it was 3 miles over GM’s recommended “break in.” the car is black with every option and probably as likely to show rash and hurt value as much if not more then your car, the fact is from day one I’ve accepted that fact and if something happened I knew that I’d have to fix it. And yea, even a nice, flat bed jer-dan truck managed to scrape up the nose towing it, and I crushed my ramps having the truck drop it’s bead down on it so it wouldn’t scrape it any worse unloading it. Sometimes life just sucks that way, you do what you can do and get on with it, I’ve literally put hundreds of passes on the car and it only has 30k miles right now.

The only advice that I have about making that kind of stuff easier on you is to try to go to the track with someone you know that can take some of the load off if something does happen, can sit around and wait, give you a ride, get you home to your truck or has a truck that can tow you home, whatever… I also have AAA just in case.

I have to admit that there is a real sense of freedome racing the formula lately, the car is such a piece of crap and i got it cheap enough that I really don't care, but at the same time there is always the consern about spending money on it on stuff that will not transfer over to a new chassis when i get aroudn to it (like safety equipment is always a hassle because I'm not going to waste the money welding a bar/cage into this junk).

That’s the reason that I shot the video, it wouldn’t make any sence if you didn’t’ see it.

I really believe that you can run an 11 now, you just have to get the details worked out.

My biggest ones are RPM vs time (can tell you a lot about your launch and shifts), O2’s, KR and TPS, that will usually give you enough info to know if you’re ****ing up or the car is and then when you know that you can usually see what else you have to look at to narrow down why/exactly what is happening.

[/quote]

Huh, somewhere I have a box of new 9 bolt parts… will have to look if I remember… I’m pretty sure that I have an install/shim kit and bearings somewhere, don’t remember about the gears, have my own stuff that I put together for rebuilding posi’s…

 

Again, thanks for the input. I did work out a trade with another TGO member. I got 3.27's and he got my 3.70's. I also have the install kit. Good deal. I'll start on it this evening.

 

I got my rear axle fixed up, as well as installing a HD 3.5" driveshaft made at a local shop. I also made up a driveshaft loop for the front and the rear. This time, I was very picky with the gear contact pattern. I purposely went from having the pinion too close and moved it too far away so I could figure out exactly where it needed to be (then I knew it had to be between those two numbers). I had the pinion in and out 6 times until I was happy


Data:
I also did some real quick data acquisition last night as well. Didn't beat on it too hard with the new pinion bearings installed, but the numbers looked pretty good.

Long hard pull uphill in 4th gear from about 3k to 5k:
AFR was 12.5 as soon as boost hit, and crept down to 12.2 at around 5k.
Intake air temp (open GM sensor)- I never got it above 100°F, ambient air was about 70°F.

I'll do some more testing Monday.

Here are some pics of my torque arm mounted driveshaft loops and the sweet 3.5" driveshaft:

 

Huh, I like the gusseted loop mount on the TA… but I don’t think that loop would be legal at the track (they require ¼” x 2” steel). I’d still love to see a clearer picture of the front mount…

 

Got some more interesting test data. DId some runs today with the ambient air temp around 90°F

1)IAT still never got out of hand. It got to 120°F after a long pull though 3rd and 4th gears, again up hill. I didn't trust to stay in it any longer, as it was apublic road and I could just see someone pulling out in front of me at a buck ten.

2)Exhaust back pressure- tested in O2 sensor port on LH downpipe. The LH DP is flattened a little to get around the steering column. With the cut-out closed I saw 10psi of backpressure! I knew the thing ran A LOT better with the cut-out open, that high backpressure proves it. With the cut-out open, I reached as much as 3psi backpressure, which is still too high IMO. However, I think most of that 3psi is in the y-pipe rather than the smashed section of downpipe at the steering column (I hope so anyway, as the y-pipe will be easier to rectify).

3)Knock retard- when under boost, it cycles between 0 and 15°. Is this normal? I can hear no audible pinging. Base timing is set at 6°BTDC and the BTM is pulling 1/2° per 1PSI boost. This is on 93 octane pump gas.

4)AFR: opinions please on the 12.5:AFR. Too lean?? AM I asking for trouble if I turn the boost up and don't get it any richer than that?

Mark, here is the front DS loop in the fullsize version. I'm not too worried about passing tech (but thanks for pointing that out- I didn't know the requirements, and I don't believe the tech guy at the local track did either when I asked him, but he said I need to have one for next time). The car is way too low for anyone to possibly see it from the ground. I mainly built the loops to give me a little more peace of mind. I've heard loose driveshafts can destroy a car. Mine may not be bulletproof, but being it is so close to the shaft all around, hopefully it won't gain enough inertia to destroy the floor pan if a u-joint does fail.

 

She goes lean at 10psi of boost. Low 13s AFR. I don't quite trust that.

May be time to do some work to the fuel system. I have the highest rate disc in the Vortech FMU, so not much I can do there.

 

That’s pretty decent for a 90* day… I don’t remember,what IC are you using?

I’m not sure that you’re really clear, is this before or after the crushed section? I’d be surprised if a flattened section really made that big a difference, I’ve seen tons of flow and dyno tests showing little if any difference. The only place that I can think of that people swear by a difference (and I don’t really believe them) is with the stock, flattend LS1 f-body y-pipes.

What is the rest of the cat back like?

To me that sounds like you’ve either got a big time timing issue or most likely false knock. 15* all at once is weird unless it’s been changed in the chip (most factory setups retard in 4* steps I think). I’d probably either put some race gas in it or try retarding more like 2*/psi and see if it makes a difference.

Any chance it’s happening just when it shifts (you always seem to see some on the shifts)

Yes/no/maybe? Most people consider safe for a blown engine at around 11.5:1. OTOH, most cars will make more power with a leaner mixture. My brother’s car does best at right around 12.5:1, and he’s been running it right around that range for years.

Asking for trouble? Well, if you run more boost and stay at 12.5 you’ll be fine, if you’re running out of fuel and that is causing you to creep up to 12.5 and you add more boost and say go to 15… that’s a problem…

Yea, I know what you’re saying, you just want it to be safe… FWIW, I’ve never seen a tech guy get under a car and actually check one, they usually just ask if it’s there.

I still can’t really tell, how is the top mounted, is it bolted like the bottom or does it have a slotted hole (that’s what it looks like in the pic)?

 

Two junkyard Ford Probe IC's mounted in front of each front wheel, angled forward.


The test point I used to test the exhaust back-pressure is right after the driver side turbo, in the downpipe. After the test point, the down pipe makes it's downward angle, and then is smashed a little to fit between the manifold and the steering shaft. The y junction on my y-pipe is very poorly done, and I think that is why I seen 3psi backpressure even with the cut-out open. The cut-out is in the area of the stock cat. After the cut-out is 2.75" pipe over the axle and a flowmaster muffler.

Its not just on shifts. It rapidly switches up and down. I'll try more spark retard and retest.



The top bolt is a through bolt also, no slots.

 

The DS and loops look good, peace of mind is a nice thing to have.
My dad broke a stock DS in his Chevy truck while towing too much weight, it banged up the underside of the bed pretty bad, but didn't cause any permanent harm. I've heard of worse, too.

The Probe IC's sound like they're cooling well, better than I would have thought. Have you measured the pressure drop across them? I wonder how restrictive they are.

It seems that most boosted cars run around 11.X AFR on pump, but 6-8 psi isn't a whole lot of boost and your IAT's are pretty low. My Talon likes 10.5-11.0, but it runs a lot of boost with a mediocre intercooler on 93. From what I've seen I wouldn't trust 13.X on 10psi either, maybe unless you are running alky injection and race gas in it.
What is your max FP with 6 psi of boost? Even if your FMU would push it further I think you are somewhere at the point of diminishing returns with the added fuel flow per psi increase. There is of course a lot you can do with the fuel system from here, but I think bigger injectors and ECU tuning are the way to go at this point.

I don't know why you would be getting cycling knock retard except that maybe the knock happens, it lowers timing, it goes away because of that, it raises timing, then it starts over, really fast. My Camaro doesn't act like that when it gets knock (N/A), it's fairly smooth and consistent. Like 83 Crossfire TA said, before you try anything else increase the BTM or throw in some race gas. I'd rather go with that option, as it leaves everything on the car exactly as is for the testing.

I think that's easily most of the problem. Flowmasters really don't flow as most of us know, and the 2.75" pipe may not help either. Could you get away with making a 3" catback and deleting the muffler?
About the Y-pipe, I wouldn't doubt it. I'm probably going to have the same issue with my (partly stock) Y-pipe until I can make a whole new one. Those small crush bent tubes make me cringe.

OBTW, what did you use to check the exhaust pressure, just a fitting to go into the O2 spot with a nipple to connect the boost gauge? Is something like that too hot for a rubber line to come in close contact with? That would be a good idea for me to know as well, with what I ultimately have planned for my exhaust setup.

 

I tested the exhaust backpressure by welding a piece of 3/16"brake pipe about 12" long into an O2 sensor plug. The idea behind the metal tubing is to cool things down to where you can connect a rubber hose. Run the hose to a gauge taped to the windshield, and your set. Works great to diagnos clogged converters (which is what I normally use this apparatuse for). I also have an adapter for 1/8" pipe thread so I can drill and tap a hole in the exhaust pipe if the O2 sensor is not easily accessible.

I'm a big fan of exhaust system pressure testing. It is easy to do and gives you a clear-cut answer as to what is going on in the system or if there are power gains available by modifying the exhaust. In my case, it proves the electric cut-out after the y-pipe was worth the $150 it cost

 

while you're at it, do you actually know that the btm is working? I've never seen one work long term. Start the car, put a timing light on it and apply some pressure on the BTM's pressure port and see if your timing moves...

 

I would go with the Spohn Relocation Brackets for 65 bucks and a little time welding them in they help alot...If you are have traction issues I would also recommend Drag Bags start running the passenger side bag at 30PSI and the drivers at 15....Then you can make adjustments from there...But that will help preload your rear.... Sub frame connectors would help eliminate body flex which would also help get more power out of the body and to the ground where it should be

As far as the 9 bolt rearends I have had 3 of them and they seem to have internal problems with the clutches.....I mainly happens from people trying to do slow burnouts then building up speed instead of just stomping the pedal to the floor and roasting the crap out of the tires because they want a longer burnout.....The problem is the clutches work off of preasure and do not fully engage when you are barely on it....Hence the limited slip not posi....

 

Update 11-4-06

Ok, brought this back from the dead. I decided not to give up on this goal just yet. Maple Grove had their final TnT of the season today, and I tried to get into the 11's one last time. I didn't make it, but I know I have the power to get there. My best run of the day was a 12.6 at 120mph with 8psi of boost and Alky injection. I was battling clutch issues all day. Details follow for anyone interested.

I decided to install a Snow Alky kit to allow a slight increase in boost. The alky spray and extra boost really woke this thing up! While I was dialing in the extra boost, I had my WB O2 in to see how the AFR was doing. At the base 6psi setting, the AFRs dropped into the 11's at the torque peak. I worked the boost up to 10psi, and I ran into trouble. I could no longer watch my Innovate WB meter in third gear under boost because the back end would step out! I've never been so excited in a car before. I could literally slide it sideways at 70mph! I wasn't brave enough to stay in it for very long in 3rd gear, so I did a few pulls in 4th gear. The first 4th gear pull I did, the clutch (a 6year old CF Dual Frition) gave up, and it went down hill from there. Best I could tell, the AFRs were around 12.8:1 at 10psi, but it was difficult to tell because the clutch couldn't hold the engine still long enough to get a steady reading.

I turned the boost back to about 8psi, and after I let the car cool for a while, the clutch seemed to hold Ok, though questionable in 4th gear. I decided I would try it on the track today anyway.

These times were with open downpipes and BFG Drag Radials, and the air was good. My launches were soft because I was trying not to overload the clutch and get it too hot off the line.

Best run:
12.602@119.88 with a 2.16 60'- this run I babied it out of the hole and shifted extra slow to try to keep the clutch together- it stuck through 3rd but slipped a bit when the torque peaked in 4th
Next best:
12.806@117.75 with a 2.105 60'- this run was my last run, and I gave it too much. The clutch slipped in 3rd and I was pedalling it through 4th.



What clutch should I get to replace my CF DF? If things work out, I may try to get a new clutch in and then go down to Cecil County Dragway yet this season. I also plan to redo my Y-pipe becuase the one I have made up for it now is very restrictive and I won't drive 1.5hrs to Cecil with open down pipes (plus I want this to be a legit 11 second run, as in total street trim).

 

Awesome! That's way more than enough power, heh. My Talon runs a few mph shy and it's in the 11's spinning partway through first.

Sideways at 70! I'm torn between saying "SWEET!" and "Wow, that's too bad". haha
That gives me hope.

Is the boost holding solid at 10 psi or is it creeping up to 10 up top? Just curious. Do you still have the FMU? You must really be pushing the limits of the fuel system if so.

As for the clutch... Lots of people have really good luck with the Spec stage 3 in the T56's, I don't see why it wouldn't work as well in the TKO (I haven't heard much about that application). I just got mine installed so I don't have much room to give a review yet, but it's not too terribly harsh and the pedal feels good so far. It's rated for 680 lb/ft in this app :O , but might be a little less in the TKO depending on the size of the TKO's clutch.

Now if you'll excuse me I have to go upload pics of my installed FMIC.

 

Beer runners during the prohibition were slapping on superchargers to get away from cops easier.

 

With the downpipes open, the boost holds steady at 8psi. With the y-pipe connected the boost creeps to 10psi no matter how you adjust the wastegates. I assume the boost creeps because the exhaust stacks up in my crappy after turbo exhaust. Even though the boost creeps, there is no noticable power increase. If you read earlier in this thread, I have 10psi of backpressure after the turbos with the y-pipe on (3psi with the cut-out open).

Yes, I'm still running the FMU and SVO 24# injectors. And yes, I know, I know I just haven't decided yet what to do WRT the fuel system. Feeling 10psi with enough fuel to match (with the meth injection) makes me really want to get this thing set up RIGHT. I'm just too lazy I guess, or too busy with work (maybe a combo of the two ).

 

Wow, yeah it sounds like your exhaust is quite a restriction. That makes me think I'll have similar problems (or worse because I have tiny internal WG's). My post-turbo exhaust is all straight through, but it goes through the modified stock Y-pipe before getting into the 3 inch "cat"back. I'll have more work to do to the exhaust to get it MD legal anyway, I may just finish making a new Y-pipe. You have a Flowmaster back there IIRC? That'll add some backpressure, heh.

If your fuel system keeps holding up with all that pressure, I would say don't even worry too much about making it perfect, heh. Ahh, what am I talking about? Get the Megasquirt and huge injectors, it's more fun that way.

The car sounds like it's a blast to drive!

 

The Y-pipe I made for my TT system is not much better than the stock L98 unit. I want to make a 2.5" to 3.5" unit sometime soon, preferably before the next trip to the strip. I have also considered a 4" cat-back from Mufflex to finish it off (still trying to decide if I want to spend $600 for one though ).

I have been seriousely considering a MS for my car. I would like to gain tuning experience on my stock L98 before I build an engine for more boost. I'm a little surprised to hear you recommend the MS when you are working with the GM ECM's on your car.

It is, and thats what counts, right?

Oh, and thanks for the suggestion on the clutch. I have a local supplier for them, maybe I'll check them out. I wouldn't be too surprsied if my car is pushing 600+lb-ft at the crank. It dynoed 468 to the wheels three years ago on junkyard turbos and 6psi of boost.

 

I would say save $600 for the exhaust and build one yourself.
dual 2.5" to single 3.5" should be plenty. That is actually what I want to do eventually.
I have the factory dual-cat Y-pipe, which seems like it should flow a tad better than the other, but I dunno. I did get rid of the worst part though, where it Y's together (after the now-missing cats). It necked down a good bit before it would have hooked to the 3" catback, so I got a 2.25"/2.25" to 3" Flowmaster Y section to put in it's place.

I mentioned the MS because I know you've mentioned it before, hehe. I honestly think the best bet would be to convert to SD and get the better versions of $58 that are out, or wait for JUNKCLTR's version of boosted $8D. Unfortunately the stock '165 system leaves a lot to be desired.
MS wouldn't be a bad bet either, but I do like the large number of things you can do with the GM ECU's, most of which with factory precision.

The Spec stage 3 should handle all that twin turbo TPI torque (the 4 T's, haha), that's why I got it. After my N/A dyno I fully expect to make 650 lb/ft at the wheels on a good tune and 15psi with some E85 mixed in (similar to the Alky injection effect, because it basically is, heh).

 

BTW, if you get a stout rear, full slicks, and bump the boost to 12 with proper tuning and fuel, you can hit 10's if you drive the hell out of it. /benchracing

 

****, that’s enough MPH for a high 10…

Are you sure that it isn’t the mineshaft/arctic cold conditions that we’ve had the last few days? (I’m sure that you being a couple of hours north of me where a friend of mine just sent me pictures of snow from only makes it better, it’s like 25* here right now and didn’t get over 42 yesterday)? Usually we get some of our best passes about this time of year, one of those nights where it was sunny all day (still some heat in the track so you can hook on any decent tire) and then suddenly it dropped into the low 40’s or so at night for a mineshaft correction factor.

You may want to double check the schedule for some of the tracks down this way. I don’t know what cecil’s schedule is like but Capitol usually runs TnT till thanksgiving or until snow shuts them down, and then they’ll reopen early in the new year if we’re having one of those winters that we get little if any snow. I think Mason Dixon goes to an every other weekend/weather permitting schedule through the winter, at least they used to.

Clutches… donno, I can tell you that I’ve seen a few dramatic clutch explosions with the Spec clutches. One of the local guys lost the bellhousing, front of the transmission housing an part of his floor pan when his went. If it was me I’d look to piece together something, maybe like a mild, streetable pressure plate that works with whatever your setup is and a grippier, race clutch disk (something with 3 or 4 “pucks”…), staying away from Kevlar (if you can get Kevlar to work for you great… the **** makes me nervous, it works great till you start smoking it or slipping it in too much, then it gives you no warning, doesn’t stink like an organic compound, and overheats and starts chattering. From that point on your streetablility coming off a light sucks).

It seems like we all eventually start heading towards a street twin, as much as I HATE mine in my ws6 (for that matter, to add insult to injury I just blew mine up, like as in on the way to work getting a sudden grinding noise and then shrapnel coming out of the bellhousing after just under 6000 miles).
----------
¿Que?

9 bolt posi’s don’t have clutches, they’re cone posi’s.

Posi isn’t a technical term, it’s an advertising term (positration) that GM came up with to describe limited slip rears. There is no difference between the 2.

 

120MPH on 8 PSI with a stock block is insane, can you go over all the mods done to this engine? I want to believe you but when I switched my pulley on the blower on my stock block I was making 17PSI at like 6000rpms and I don't remember the car pulling that crazy.

 

Yes, the air was cold and that had a lot to do with it. My slips do not have the ambient conditions printed on them, but it had to be in the 40's. There was frost on my car when I left for the track.

I know the alky injection and extra boost made a word of difference because I did test back to back. After installing the kit Friday night, I ran it with the reservoir empty and the WB connected and the boost at 6psi to get some heat in the motor and base line AFR numbers. It ran good in the cool air, but barely spun the tires through second. I came back to the shop, filled the reservoir with 1/2 Snow Performances' boost juice to 1/2 Denatured alcohol. I turned the MBC to bring the boost to 8psi and it felt great and the AFR's were around 12.2-12.4:1 and thrid gear pulls felt very stout. I then added another 2 psi (10 total) and thats when the 3rd gear tire spin and clutch issues came up. Keep in mind also this tire spin was on 18" street tires and the road surface had to be cold at 10pm Friday night!


My first run Saturday was on 10psi of boost and a pretty hard launch, but it the clutch was toast right away and I backed off early. That run was a 12.7 at 111.

The specs:
- Stock L98 cam, heads, pistons, etc with 97k miles
- Only engine mods are Summit 1.6 rockers and heavier valve springs (they're what my machine shop called Z28 springs??- he's old school, but thought thats what I needed so I ran 'em)
- Stock TPI base, runners, and TB, very mild porting on plenum
- Stock MAF ECM, Ford SVO 24# injectors, stock in-tank pump, Vortech booster pump, Vortech SFMU
- MSD 6AL, MSD wires and coil, MSD BTM pulling 1/2° per pound of boost, base timing of 6psi
- Snow Meth kit with 375ml (IIRC) nozzle
- Tremec TKO, 3.27 rear gears, stock rear suspension
- Twin T3/T4 hybrid turbos, twin probe GT intercoolers, turbos mounted on modified stock L98 manifolds
- I raced with open down-pipes
Thats all I can think of right now...
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17psi would be about crazy. I only run my motor to about 5500 and thats all it wants. I noses over around 5300 or so. Did you run your car down the strip at 17psi?

 

I never had a chance to run it at the track since the 2 6 rib belts would stretch to the point where I couldn't get anymore tension on them so they would slip like crazy so I just put the other pulley back on. I think I might try again this next summer see if I can do something like adding another idler pulley or something to give me some more tension, either that or AFR heads and cam.

Was looking at one of my data logs with the 17PSI pulley the other day and I see I'am only making about 12PSI at 5000RPM's where my TPI intake motor is probably making its most power. Kind of like you about 5400 is tops before power would drop off fast for me, only reason I rev her that high was to hear the sound the blower made spooling up much cooler then the current pulley.

Even with the extra boost most I think I would get would be 110 mph I'am guessing since I trap about 106 average now. You really make me want to break out the tools and start modifying my stock L98 manifolds

 

89JYTurbo- I see that your running a turbo with a blow through MAF setup, and a Vortec fuel pressure regulator. I had a question about your tunning. I can understand that the Vortec fpr can help when your MAF sensor is maxed out. I dont understand how it helps when you are under boost, within the measureable limit of the MAF. If the MAF sensor is measuring the air and the rpm, it should be able to add the proper amount of fuel whether your car is boosted or not (I may be wrong). However if your fpr is adding fuel due to boost while your MAF is still within limits, wont the car run rich?

Thanks

 

I just put a SPEC stage 3+ in last night, and I'm not very happy with it. You can hardly take off without severe chatter; it rattles the drivetrain so bad you think somehing is going to break. The only way to make it smooth is to rev it to 2k and release the clutch quickly, which makes parking lot manuevers very difficult to execute smoothly. I don't consider this a street clutch, unless it smooths out during break-in.

It better hold the power if I have to put up with poor drivabilty.
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BirdsOnly:

I don't know if I'm the one to ask about tuning. I can't explain why it works, but it does drive pretty well. Not quite like a factory tune, but it is smooth and crisp, exceptfor new SPEC clutch).

 

My stage 2 spec for my t-56 was the same just took some miles to break in but it never worked out for me the 2 that they sent me hence why have I have a mcleod street twin Hopefully you have better luck with your stage 3, did you get the one with the solid hub or did yours have springs in it? Seen a bunch of posts in the past where the springs would break but this is for the t-56 clutches yours might be different.

 

My Spec stage 3 was TERRIBLE when I first put it in. I put about 600 city driving miles on it, and now its great. It'll chatter a little below 1500 on take-off and it seems to let out a little high (on the pedal), but it still holds anything I can put through it. It smokes the tires from a roll in 3rd (3000rpm 3.23 gears).

 

Its good to hear that they do seat in. I talked to SPEC and they said the clutch is designed to engage quickly and I just need to 'get used to it'. I've driven all sorts of manual trans cars, and I've never had such bad chatter. Tony, what was the problem with your stage 2 SPEC clutches? My stage 3 does have a sprung hub, but you wouldn't know it by driving it

 

My stage III was pretty chattery at first, now even with only 100 miles or so on it it's better already. Probably has more to go.
Good luck with yours!

 

My first one just didn't work at all was slipping right from the start, god that was a nightmare, this happened when I just first installed my t-56 so me thinking it was my fault I did everything I could to figure out the problem. Then one day I said **** it I'am sending it back, they told me the pressure plate was bad The second one they sent me worked for everyday driving but didn't liked being slipped at all and would turn to butter, pretty sad too since my car was basically stock without the blower at the time. Hell even my cheapo clutch I bought for the t-5 did a better job.

 

Thats so much fun, isn't it? ANy dyno or 1/4 miles on your car??

Thanks for the input on the clutch too.

 

It was all fun and game untill about a half hour ago. Showing off for a VW club up the street from my house I ripped out 3rd!

The only numbers I have on my car is that the 38pph injectors hit 98% duty cycle at 5800rpm and 12.5-12.8 AFR. According to the Holley software, that puts me at 545hp at the flywheel. But yeah the clutch is good, still really agressive, but fun to drive.

I just rebuilt the tranny when I put the clutch in 600 miles ago.

 

The clutch shatters alot and needs to be broken in.

I remember riding in a 02 z28 that just got a spec stage 3 to a dyno meet, sadly with a lid and catback he was the second highest hp rating at 336hp 342tq but a stock 05 gto got the highest with 346hp

 

Sounds like you need some 42's.

I worked at a VW race shop for about a year and we've had nothing but trouble with SPEC clutches. We've had one or two throw out its springs, or the driveability(sp) was just plain horrible! It seemed to not matter if it had a spring hub, solid hub, marcel or not, they all sucked to daily drive.

Fortunately, we have OEM performance options that work well for mild/moderate cars. But for the high horsepower cars (300-600whp) we had to go somewhere else.

 

and a new tranny

 

I built a new Y-Pipe this weekend. This should flow a little better than my old unit which was two 2.25" pipes feeding into a single 3". Even with the cut-out open, I had 3psi of exhaust backpressure when measured at the turbine outlets. This new pipe is 2.5 into 3.5. The "cat-back" exhaust is still the 2.75" over axle pipe into a wheezy flow-master. Its VERY quite with the cut-out closed, which I like .

Hopefully there will be no more need to run open down-pipes at the track. Plus this new unit looks 15X better since I've learned how to weld since I constructed the orignal Y-pipe

 

Very impressive, you should sell kits

Ever thought about moving up to a 3.5" catback?

 

Yes, I was considering a 3.5 or 4 cat-back from Mufflex, but decided that the cut-out will do. The Mufflex kits start at $530, and the electric cut-out was only $200. Only problem is that my stock-cammed L98 sounds like an old farm truck with the muffler rotted off with the cut-out open. Hopefully the open dump will sound better once I give it some cam.

 

I built my 4" cat-back pretty cheap:
https://www.thirdgen.org/forums/exha...-cat-back.html

 

You did a nice job on that. How was the clearance in the over-axle section? My 2.75" pipe is crushed a tad in the area of the panard bar support, and I didn't think a 3.5" or 4" pipe would fit in there. FOr now, I'm happy with my electric exhaust cut-out, but someday I may want to build that 4" cat back and go really fast through a muffler.

BTW, I would love to see soem 1/4 numbers on your car. You combo seems to be a step ahead of mine in almost every sense, you ought to see what it can do!

 

The 4" pipe fit perfectly in there. It was not smashed at all, but it pressed against the heat-shield for the trunk a little. I was very happy with the fit and ground clearance.

I had planned on getting some times at cecil sometime this month, but now that my tranny is broken, I might not get it fixed in time. I drove it about 15 miles with 3rd gear broken, and other stuff started to go bad, like 5th and reverse, probably a chunk of 3rd stuck in the 5/R shift linkage. So I can't drive it untill I fix that tranny or get a new one. Fixing this tranny would probably just be a waste of time and money when it blows up again in another week. I'm broke $$$.

 

I'm planning to go to Cecil Saturday. My brother is going to haul my drag radials and a jack along down for me, so I can get some runs on the 18's and the DR's and see the improvement back to back.