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Underbody braces, turbos and more!

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PostPosted: Mon Aug 19, 2013 11:18 pm 
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Another top view of whatever this mod. is:


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PostPosted: Mon Aug 19, 2013 11:32 pm 
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And lastly, I wonder what built this nest in my modded Forsa Turbo since I parked it after blowing the head gasket?


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PostPosted: Tue Aug 20, 2013 12:46 am 
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That is a fast acting BOV that has been routed to recirculate the
relief pressure back into the intake tubing.

Check the OE POV on the I/C, I bet its been removed and
blocked off.


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PostPosted: Tue Aug 20, 2013 1:29 am 
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JamalSpelling wrote:
That is a fast acting BOV that has been routed to recirculate the
relief pressure back into the intake tubing.

Check the OE POV on the I/C, I bet its been removed and
blocked off.


Thanks for telling me what this is. I thought that you would probably be the one who knew what it is. The guy I bought this car from was right into turbos and he explained it to me but I guess I screwed up my explanation of it earlier in this thread. I want to get a new rubber hose and NipponDenso thing and cut the new hose to splice the NipponDenso thing in closer to the throttle body because where it is it partially blocked the oil cap and I broke it when I was removing the oil cap.
I like this one because its the fastest of my turbos, my other four are all bone stock. And its a Suzuki Forsa turbo so it has nice stuff on it like power mirrors, a clock in the instrument cluster, and a better console that my Firefly and Sprint turbos don't have. And its got that strut tower brace.


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PostPosted: Tue Aug 20, 2013 1:45 am 
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1987TurboSprint wrote:
The VAF has a fuel cut that kicks in around ~13-13.5psi. The mk1's do have a pop off valve that opens at ~8psi to prevent surging boost pressure back through the turbo when the throttle is shut while there is pressure in the intercooler (it's attached to the ic). And you do have to shim the spring if you want to run more than stock boost or it will open and limit you to ~8psi. BOV's don't dump into the exhaust. They are either recirculated and dump back into the intake after the maf but before the turbo or they vent into atmosphere. And BOV's are not what you use to limit overboost. You're think of the wastegate. BOV's should only open when vacuum is applied to the back of the diaphragm, when the throttle is shut. The wastegate is what controls how much boost the turbo puts out. And the wastegate does dump into the exhaust. But I would never reroute the already burnt super hot air dumped by the wastegate back into the intake.



I just reread this, now that I understand that the modification on my turbo is a blow off valve and how it works I understand this entire post.


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PostPosted: Tue Aug 20, 2013 2:14 am 
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JamalSpelling wrote:
Quote:
Instead of the blowoff being wasted by being dumped into the exhaust, its rerouted and fed back into the turbo setup someplace

You cannot do this on an MK1 G10T, it does not work. I tried and nearly blew off the oil cap.


Aha !!
Now that you've explained what the modification on my turbo car is, it seems to me that, " instead of the blowoff being wasted its rerouted and fed back into the turbo setup someplace" is exactly what the modification on my car is doing. It seems I got at least some of the explanation of the modification right the first time.


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PostPosted: Tue Aug 20, 2013 8:29 am 
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Now you got it. :wink:



Quote:
When I broke the plastic tube off the nippondenso thing I plugged the rubber hose connected to it with the 1/2 inch drive socket extension you see sticking out of it. The car was then even faster

Hmmmm....I wonder why? :idea:


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PostPosted: Tue Aug 20, 2013 9:09 am 
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JamalSpelling wrote:
Now you got it. :wink:



Quote:
When I broke the plastic tube off the nippondenso thing I plugged the rubber hose connected to it with the 1/2 inch drive socket extension you see sticking out of it. The car was then even faster

Hmmmm....I wonder why? :idea:


After I blocked off the bigger rubber hose with the 1/2 inch drive extension I should have left the smaller tube attached to the NipponDenso thing where it was instead of removing it and plugging it with the golf tee, because the vacuum signal through that small tube is probably what opens the BOV, and it wouldn't have built up the excess boost that blew the head gasket in a very short time. If I'd left the small rubber tube attached to the NipponDenso thing then the extra boost would have been released to the atmosphere through the broken off tube in the NipponDenso thing. Is that right? All the unregulated overboost made the car run like a rocket for a couple of days until the head gasket blew.


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PostPosted: Tue Aug 20, 2013 4:27 pm 
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Generally, the vacuum hose just assists the BOV
ensuring it dumps the pressure between shifts.

Depending on what the factory setting is on that BOV,
you may not have been producing enough boost to overcome
the spring pressure.

OE turbo boost is around 6 PSI, OE POV valve vents around 10 PSI
and fuel cut kicks in around 12 PSI. (Don't quote me, I don't remember
the exact specifications, but this is close enough for relevant discussion.)

It is unlikely you were overboosting, unless you have modified the
factory boost settings with a boost controller. If you were overboosting
in the neighborhood of 12PSI then the fuel cut would have kicked
in and the check engine light would come on momentarily.

It is likely the headgasket was compromised due to normal use.

If it were me, I would go back to the OE set up.
Get rid of the extra tubing on the I/C, ditch the BOV and
put back on the POV. Install an quality, inexpensive
MBC and adjust the boost for maximum pressure
just below the POV valve opening point and Fuel Cut Point.
If your engine is healthy, this will be fast enough and reliable.

In fact, assuming your lower engine is healthy.
I would start with a spare head/intake/turbo/downtube.
Have the head rebuilt, and clean everything else up
and do what your want (port head/ intake/ exhaust/
gut the precat etc.) When you have your spare
assembly ALL READY, then you can swap it out with
ease. You have so many of them, this would be ideal.
Once you start tearing it down, you're bound to
find other problems, snap some bolts, strip some studs,
find a bad turbo...etc. It's so much easier if you do
all the bench work ahead of time and make sure
you have all the parts.


This project was a relatively short duration due to the
fact I had a block & head prepped and most work
was done on the bench. The most time consuming
part of this was cleaning up the engine bay, and
cleaning up the wiring. When it came time to address
the turbo shortly thereafter, same deal. I did run
into plenty of problems, but basically prepped a set
of backup parts for the job so that when I pulled
off the assembly I was almost ready to go.
viewtopic.php?f=32&t=56235

With the boost level set up a few pounds, just
below the POV & fuel cut point, this car is very fast.


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PostPosted: Sat Aug 24, 2013 5:11 am 
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^^^ Totally awesome info. Jamal, thankyou. If you hadn't taken the time to post all that info. about that pop off valve, blow off valve, etc. etc. I'm sure I probably never would have found out about it because I'm basically a learn as you go parts remover and replacer, and if stuff isn't in the FSM or a Haynes then my chances of learning about it are slim and none.( Well, except for the stuff Phil 'n Ed, and Glacierburst, and Codyb76,and SuprF1y, and T3 ragtop, and others tell me.)( and stuff I googled, now that I think about it, but you can waste a lot of time trying to google stuff to find out about it and still come up dry)
Thank you for explaining how the blow off valve modification on my car works because if you hadn't then the only way for me to find out how it works would be to pay some mechanic a pile of money, that I don't have, to fix it, and that likely isn't ever going to happen.


I used to do a fair bit of monkey wrenching on my cars but I haven't done much in the past four or five years because about that long ago I did a blown head gasket replacement on my '88 corolla and I spent a lot of time and money trying to do a meticulous job and when I was done the thing still leaked which really pissed me off and destroyed any enthusiasm I had for doing any work at all on aluminum cylinder heads. I miss my 1972 Austin Mini, cast iron head, cast iron block and 50 MPG.( My '71 Spitfire is even better, cast iron block and cast iron head held on with studs and nuts, not bolts)( and twin SUs)( maybe its a'69, its got the earlier rounded body style, I can't remember exactly) I took the head off that Mini, paid a guy 20 bucks to do a valve grind, put it all back together and adjusted the valves and it ran like a top. And that was way back when I knew little or nothing about working on cars.( And I'm not saying I know that much more today, I'm just saying that what I know is that if God had wanted Man to make durable heads out of aluminum, then He wouldn't have given us Cast Iron.)( What I really want is a Mk1 turbo head made out of titanium, one day I will make one.)


Any way, my lessened interest in monkey wrenching is why I have 18 Forsas, Fireflies, Sprints, and Swifts and 17 are undriveable, most because the head gasket is blown, and I have to pour a gallon or more of oil into #18 every day to keep it going. It's easier on my brain and stress levels for me to buy another cheap Forsa, Firefly, Sprint or Swift than it is for me to fix the ones I've already got.
But the supply of driveable and cheap used Forsas, Sprints, Fireflies and Swifts seems to be drying up so now I've decided to start fixing the ones I've got. ( Plus giving my hot little ex girlfriend the boot has freed up a lot of time and money for me, and gotten me off the fast road to nowhere.)

So I really appreciate you sharing your knowledge on fixing these cars up and keeping them going because I'm going to be doing quite a bit of fixing them up over the next while. I like your threads about rebuilding the Mk1 turbo engines and whatnot because your philosophy seems to be to get them going good in a basically stock configuration with some mild upgrading, which at the moment is all I have the time, cash and knowledge to do on my own cars, as opposed to building some sort of all out extreme race engine. All my cars are daily drivers, I don't have the time or money to get into racing ( at least not on a racetrack anyway, if a race happens to occur while I'm doing my daily driving, well so be it, and it's usually with some lardass goof driving a bright red $60,000 One Ton Pickup with duallies, that he has absolutely no use for, who's pissed off my little $450 turbo econobox beat him to the punch in traffic).

That's why I think your Manual Boost Controller modification is so excellent. It enables you to maximize the output of the stock engine without a substantial investment in time, cash, or effort. Getting the most out of what you already got. Down the road if I find the time and cash I would like to get into doing some major performance upgrades to one of my Mark 1 turbos, but at the moment I've got my hands full just getting them all back on the road in stock configuration. So thanks again for the excellent info. and knowledge in your postings, its right on the money for what I'm doing right now and I can use all the help I can get right now in getting my cars back on the road.


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