Lessons learned and interesting observations (turbo: week 1)

[Guest bastaad525]

Just a warning... this is a very long post.... VERY long!! It's a rant/vent/record on all the things I've 'learned' so far with this car

 

Well, it's been almost a week now since I picked up my '72 with the '81 turbo motor in it... there's been a lot of ups and downs with it in such a short period of time, but things are definately getting better. We found that one of the problems causing the car to not run right, was that the cam timing was off. So, fixed that, and now it almost feels the way I expected it to. Pulls hard, lots of torque above 3k. There's still some major hesitation in there that we haven't been able to figure out. I'm gonna go back on friday and my mechanic will mess around with the airflow meter and see if that takes car of it. The plugs still show a light grey ashy appearance with darker ash around the base... I found out that the grey ash is actually deposits left from race fuel, which the owner of the donor car would run. Also found out that the car had some SERIOUS vacuum leaks... the AFM to Turbo boot was cracked really bad on the turbo side, and the hose that vents the valve cover into the intake had another one. Swapped on a new afm-turbo boot, and took off the valve cover hose and put a little K&N filter on there that I had from my last ZX still (good thing I decided not to sell all these little parts!). Every little thing seems to make some improvement. I still haven't messed with the boost. Aside from all that, there are some interesting things that I've learned in the last few days... some were stuff I had already been told on here (shame on me I know...).

 

Blowoff Valves can do funny things.....

 

For anyone who is running your BOV open to atmosphere, you may want to reconsider hooking it back into the intake. When I first installed the BOV, I didn't have any open vacuum ports on the intake so I just left everything disconnected. To my surprised, it would still vent between shifts, so I didn't worry about it for the day. The next day I went up on the freeway and realized that it will also vent and KEEP venting just about any time you put constant boost on it!!! It was a revelation to say the least, when I'm cruising down the freeway at some 80mph and realize what that interesting loud hissing noise is, and why the car seems to be running dog rich the whole time . Another thing I noticed after installing the BOV, is that the rpms dont want to drop right away, say I let off the throttle and put it in nuetral, the revs will hover for about a half second or maybe a full sec, before dropping down. This was causing some rough, jouncy shifting. So I hooked up the vacuum line, problems solved, right? WRONG. Sure now it would vent pretty much ANY time I let off the throttle now (more whooshing and sneezing... that's gotta be better right? sure sounds cool!) and will stay closed up on the freeway... or would it??? Now it was still venting too much OFF boost, and either sucking too much air in or still venting air, and the car is still not running it's best, especially whenever I would transition from boost to vacuum to boost, the car was stumbling and surging all over the place. And the revs? Well now they would drop back to idle after letting off the throttle... and then they would keep dropping... and then the car would die. Or sometimes it would just bounce up and down a few times before settling back where it's supposed to be. Oh and did I mention the HUGE puff of black smoke bellowing out of my exhaust from running too rich every time I would shift and all that air would be vented to atmosphere, while the ECU still supplied the fuel for that air that wasn't there anymore? Yep, I know, you guys told me so So I rushed to Autozone the next day and spent a few hours to figure out and install my own 'custom' hoses to vent the BOV back into the intake boot, which is when I found out the hose to the valve cover was bad... no big deal that just freed a port up for the BOV to vent into So, no more rich smoke, no more surging on the freeway, no more bog between shifts, and sadly, no more sneezing to be heard However, one weird thing was that the hesitance for the RPMS to drop has come back. Get the car rolling in gear, rev it up to like 3k, quickly put it in neutral and let off the gas, and the rpms will hover... very annoying... any idea why it's doing this? Still better than just cutting out and dying though next lesson....

 

The exhaust debacle and the effect exhaust sound can have on how the car feels.....

 

So when I picked the car up, all it had in the way of exhaust was the downpipe off of the turbo. After chatting with a lot of guys here I wasn't sure what to expect here... when we fired it up, I was surprised that it actually was really not that loud... at idle. Anything other than idle and it was a roar that would turn every head I passed. So, having a very limited budget, I had to figure something out. Some people suggested to me to just extend the pipe out to the differential and point it down. I priced this at the muffler shop, $60. Which was about all I had left... so I had it done. What this got me was an even LOUDER exhaust, partly I assume because now it was bouncing up off the ground, and then reverberating around the body of the car, which made it much louder INSIDE the car than out! And still, turned every head that I passed... not good. Dont get me wrong, I value each and every oppinion given to me by folks here, but this little trick just didn't work for me. Though I could see why some people might like this sound... the three different auto parts stores I went to, the employees would all comment on how good the car sounded like this But that wasn't the half of it... the real kicker was the copious amount of exhaust that was now finding it's way into the car and into my lungs enough to bring tears to my eyes and cause my voice to turn all scratchy and harsh... how any of you guys have done your exhausts this way is beyond me. This was even worse then before when I had no rubber strip between my rear hatch, and my tail light seals were gone. MUCH worse. So... back down to the muffler shop today, and another TWO hundred some-odd dollars to put on the 'rest' of the exhaust, and glasspack to quiet the noise. Two hundred dollars that I didn't have, mind you... luckily he was a friend of a friend, and let me write him two checks each for half the money, one to cash this friday and one to cash next friday. However... I'm back down to 2 1/2", NON mandrel bent exhaust I am being honest when I say though, that I really didn't seem to notice any increased turbo lag and it still feels just as torquey as it was before. Not to dispute the effects of a restrictive exhaust on a turbo... maybe I just dont feel it because I wasnt too used to how the car was driving to begin with.

 

But this brings me to the second part of this lessons 'title' and that now, if anything, the car feels much BETTER than it did before. When I first just had the DP on there, and also didn't have a working tach... the stumble, lag and the way the car would cough whenever I got on it were very pronounced. Then when I added the first pipe to the diff, and got my tach working so I could see where the revs were, and drive more in the power range of the motor, the car felt a bit better as I would let it rev higher, though I was still afraid to get on it too much because of the incredibly loud sound it had. Now today after I put just a glasspack... which IMO has quited the car down far better for a straight thru piece of pipe than any baffled muffler I have ever used... now I'm not afraid to really get on it, and of course now the car feels almost perfect... still some stumble in there at low revs, which I"m still not convinced is turbo lag (I thought T3's didn't HAVE any lag) but no more backfiring or coughing that I can hear. So while my brain tells me that adding this exhaust should have made the car slower... my foot and butt seem to say its' only getting faster. Does this mean I'm not going to eventually go with a full 3" mandrel bent exhaust? hell no... all in due time, all in due time

 

Well... other little things have come up, here or there. Sometimes when I start the car... I guess fuel pressure backs up or something and the FPR suddenly will vent a large amount of fuel back into the tank. All I have to go on is that after I start the car, I will suddenly hear a very loud hissing sound coming from the filler neck, which will last a good 20-30 seconds. And fill the car with the lovely odor of fuel for about 20 mins I assume that it's fuel returning from the fuel line... First time I heard that noise though I flipped out... though my fuel pump had decided to supply my fuel to the ground instead of to the engine

 

Now that I have really pushed it a few times, I've noticed a second stumble, much harder to detect if I weren't constantly watching the tach. It will occur at WOT, right at about 4k-4.5k revs... it will stop there for a tick, before continuing on with it's smooth rise up to 5k. I can sorta actually feel this hesitation if I'm really paying attention.

 

And lastly... '82 tranny + 3.54 = the widest gearing I've ever driven! A bitchin OD that will carry 75mph at a very relaxed 2500ish rpm (still can't tell if my speedo is still off or not). Downside? Taking off from a light in first is very anticlimactic. I havent done a clutch dump launch yet... dont know why I've been afraid to try, but doing clutch slips... the car just doesn't want to move until at least 2500k. I've got to totally relearn how to drive Feeling that turbo come on is one hell of a fun ride every time though. My friend, who has owned everything from a 400hp '64 mustang, to a shiny new Toyota Scion (the bastard) was very impressed by the torque when I took him for a spin. At stock boost.... It really does feel like it pulls harder than my built up N/A did, but I think this may be in part to the suddeness of the boosts onset, whereas the engine torque curve was very flat and gradual, you didn't really feel it come on. I haven't timed it yet to see if it's actually any faster, but with the saggy launches somethign tells me it's not. I can't WAIT to up the boost to 10psi on this thing though!!!!!!!!

 

Well that's about it... the car starts easy, is drivable, idles well, holds good vacuum at idle (between 19 and 21) doesn't run too hot at constant 7-8psi of boost (constant being a relative term of course) and is just about ready for stage 2 and the zoom zoom. An FPR is next, possibly a fuel pump, and the piping for my buick GN I/C. And of course... chasing down the rest of the bugs.

 

Thanks again everyone for all the tips, advice, and words of support and encouragement during these hard times she's almost there!!

[Sparky]

Well,

 

Im sorry the exhaust didnt work out for you. I guess im just a glutton for punishment with my setup

 

What kind of BOV did you get? I bought a GFB hybrid BOV thats got two ports, one to vent to atmosphere, and one the vent back into the intake. they are offset so that the intake gets vented first (at low speeds and boost.) this helps with the problem you where having (and that most AFM cars get with a BOV) and still gives you a good SPWOOSH sound.

 

anywho, glad to hear its coming together nicely...

[Guest bastaad525]

1g dsm BOV. Anyways, though the whoosh sound was cool... I kinda like this way better... I always was saying I didn't really want anyone to know whats going on under my hood, and that BOV venting is a good signal to anyone who knows anything about cars. So it's all good... now about the only clue as to the forcefed nature of the engine is the slight whirring sound the turbine itself makes, but I doubt most people would even notice it unless they knew what to listen for.

[Guest bastaad525]

Another interesting discovery here.... apparently my brake master cylinder isn't taking kindly to all the heat coming off the turbo. I'd have thought it was used to it as there was a header there before with the N/A engine... and I gotta say I dont feel as much heat coming out of the engine bay now when I open the hood as I did with the N/A in there.... but I swear my brakes get softer, easier than they ever did before... Now I gotta think about how I can make a heat shield in there

[yo2001]

I'm running Greddy type-S recirculating to from of turbo with 1 1/2 inch radiator hose. I can hear my BOV btw shift.

[Guest bastaad525]

yeah I can kinda hear it in there, very faint... again, though it does sound cool, I really prefer it not being so loud for everyone to hear it. When they get beat, let them wonder

 

 

does anyone have a clue as to why my RPM's aren't dying down right away between shifts or when I let off the throttle and put it in neutral?

[yo2001]

probably from the back pressure by the turbine wheel cause the rpm to stay up little longer.

 

Get your booty on the AIM

[Guest jt240z]

Make sure you have some heat shields around the brake line and switch assembly areas. The turbo generates a lot of heat around the break area in the engine bay. You could be starting to feel the first signs of brake fluid boil. You may also want to consider replacing the fluid with synthetic DOT 4. It has a higher boiling point.

[Cody 82 ZXT]

One major piece of advise is to always be on the look out for vacum leaks. This will cause so much frustration in the theses cars it can make you pull your hair out if you can't find them. Also like you said there is not much there below 2500 or so RPM's. Like you said learn to drive it and will not be as noticable. Also many of the larger t4-t3's actually have better response than the factory t3.

[Guest bastaad525]

heheh I just did another look over on the engine right now for any leaks... checked like 20 times in the last two days is the amount of vacuum shown on the boost gauge at idle a good indicator to show if you do have any leaks? Just doing normal driving around the street I've already adapted to driving around the lag... it's launching that I can't seem to get right, like if I really want to take off from a light.

[fl327]

Use the "lag" as a means to launch quicker. Coming from an NA four barrel carb SBC background (the only way I will do NA again is with CARBS), I had a very hard time learning how to drive with boost. I have learned to drop the hammer at 3k on the street and just power out hard. Remember, 7.4-1 cr engines are not going to be as responsive at a 10-1 stroker NA engine.

Also, just about any of the newer turbos out there will spool faster than the stock t3, as new technology is capable of making bigger turbos spool quicker, and take a lot longer periods of sustained high boost as well.

i really think once you get the system nailed, you will be happier than a clam with what you have there. First I said" 10psi is enough for me"

then I said "12psi is good" then I said "15psi is nice"

Now im bored of all three and Im topped out on fuel!!!

Watch out, these guys are right, boost is addictive. I have to complete my turbo setup to get it ready to go and bump up the fuel system, so I can try 18psi, then once I get the hang of the fuel system

15psi, and ball bearing T4 action..HELL YEAH!!