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Upcoming MPI Swap Thread - 1989 TSi


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#41 Chad

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Posted 08 October 2017 - 03:20 PM

If you run that front port, you will overheat the back of the head and will likely crack it over time.  

That passage in the stock manifold has a very restrictive flow restrictor inside the intake (where you cant' see it).  It's just a trickle flow rate.  It's also only for TBI, which you don't have. Running both intake ports to that steel port will starve the back of the motor for coolant flow in the back.  Most of the coolant flow will take the easy path out the front port.

If one is going to argue that it's done that way on the magna (flows out that port factory), you have to keep in mind the magna thermostat is in the back where that rear port now flows.  It has been removed and that rear port is now the only way to get water to flow into the back of the head.

Also, on the magna, that front port was restricted by the factory.  It is a large nipple, but the inside diameter of the port is only 3/16" .  Trust me on that, I've cut up over 100 of them.





#42 Matt888

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Posted 08 October 2017 - 03:26 PM

Ok, I edited my post after reading your response.  Mind you, I'm not trying to stir the pot here and understand there's different approaches here.  I just didn't want to press on with the install if I was way off course.

So, following your logic I believe...   Keeping that hose/port blocked off back there ensures adequate water makes it to the rear of the motor.  By not circulating some of it back to the front, I'm going to be ok.  I didn't waste 7 hrs of my Saturday?  :)  You've done alot of these magnas.  

I appreciate all of the responses.

Edited by Matt888, 08 October 2017 - 03:37 PM.


#43 Chad

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Posted 08 October 2017 - 05:01 PM

Yah, I didn't intend to sound too assertive, just making sure I was clear that it's done a particular way for a particular reason.

#44 Woody

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Posted 09 October 2017 - 10:58 PM

Yeah I missed the same thing and got a bypass pipe put in place.
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#45 Matt888

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Posted 12 October 2017 - 06:52 PM

Slowly finishing up.

Question:  The stock intake tube had a vacuum line that went to the stock turbo's wastegate.  Can I just run the vacuum line from the wastegate to the vacuum ports (with a T there) on the side of the MPI intake?  Or is it important to have that vacuum connection from the wastegate go to the intake pipe, which is upstream from the throttle body.

Trying to determine if I truly need to add a vacuum port on the intake to the MPI like it did in stock form.

Thanks!

EDIT:  I believe the answer is yes, I need the wastegate connected to the intake.

Edited by Matt888, 13 October 2017 - 11:14 AM.


#46 Chad

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Posted 13 October 2017 - 12:16 PM

Sometimes the e.g. is connected to the turbo compressor housing,  there is more than one correct answer.

#47 Matt888

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Posted 13 October 2017 - 10:52 PM

While on the topic of vacuum lines...

Other than a vacuum line to the MAP sensor, valve cover, aftermarket boost gauge, and the wastegate, do I need to be connected to any other vacuum lines with an aftermarket ECU and MPI conversion?   There's vacuum lines running all over the engine compartment and what needs any of that?  There's opportunity for leaks everywhere and I'd like to keep it as simple as possible.  Thanks!



#48 Matt888

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Posted 13 October 2017 - 11:26 PM

Doing a search, I see that I forgot about the FPR and HVAC system needing vacuum also.  Darn, there's alot of stuff requiring vacuum lines after all.  I had decent vacuum readings prior to converting over to MPI, just was hoping to clean out alot more of the hoses.  It seems everywhere I look there's a vacuum cap starting to crack, etc.

#49 '87quest

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Posted 14 October 2017 - 09:44 AM

Don't forget your BOV too. It's not as complicated as you think though,
1. FPR
2. BOV
3. Wastegate
4. MAP Sensor
5. Boost gauge
6. HVAC

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#50 psu_Crash

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Posted 14 October 2017 - 10:43 AM

HVAC = optional :)
Although I so miss it
'86 Starion, MPI with MS2extra, Ebay To4E 57 Trim (in testing), P&P head, OS SS Valves, Wiseco +.030, ARP head/rod, O-Ringed Block, Schneider 284-H, prepped rods,AEM H2O/Meth Injection, Mighty Max CAS 4 Direct Fire Wasted Spark, BSE, Tial 38mm, JDL exhaust mani, HKS turbo timer and EVC3, AEM UEGO, 3" DP into 2 1/2" Dual Exhaust, 75# Delphi's, Magna modded by Chad, Accufab FPR, Walbro 255, D2 Coilovers, Poly Bushings, Funk-Lock, LED Tails and Dome ... etc^4
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