Ver 7 Engine Problems
31 March 2003, 10:13 PM
#1
I am aware of several engine failures on ver 7 cars and would be interested to hear of any first hand experiences, indicating the nature of the failure and the state of tune at that time.
I am hoping to identify any potential inherant weakness. While I hope this is an open topic I can also be contacted per profile.
I am hoping to identify any potential inherant weakness. While I hope this is an open topic I can also be contacted per profile.
literally as its in the middle of the engine bay 
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03 April 2003, 07:54 AM
#8
Seeing as no Sti7 owners have chipped in I'll have a turn.
From what I've read here, which is owner accounts and someone on a test drive (John Felsted?), they generally have mapping issues from the factory.
I can remember 3 blow ups of "cruising on the motorway and then bang" type, and JF was test driving a dealer car which he said was detting like mad and didn't continue, car blew the same day I think.
From the engine point of view, if you're looking at running a standard Sti7 engine with your turbo set up etc, then It's probably viable. The guys on NASIOC have done the most in this regard, where putting in a Sti short engine from japan is a common thing. Plenty of reports of running what must be over 400 crank HP on the standard engine (but then what is john banks doing?), one has even got 425wheel HP on such a setup (but dyno numbers are flaky at best in the US).
The newer engines have uprated pistons over the previous Sti engines, and uprated rods which are supposedly (from Subaru info) made from a better alloy with better processes and I think even nutless bolts on the big end cap.
The new Sti crank has additional oil drillings on the mains, BE remains the same.
Sti7 heads with the AVCS would be a very nice addition I beleive, if you can get even a basic control of the AVCS (possible even without the factory electronics) then you would be looking at bringing the start of the useable powerband down 500 rpm (see results of Jeff Sponaungle on NASIOC).
What does all this mean? Maybe Subaru hasn't learnt it's lesson with regard to mapping for UK fuel yet? I don't know, but the actual engines seem very good for a standard unit.
Paul
From what I've read here, which is owner accounts and someone on a test drive (John Felsted?), they generally have mapping issues from the factory.
I can remember 3 blow ups of "cruising on the motorway and then bang" type, and JF was test driving a dealer car which he said was detting like mad and didn't continue, car blew the same day I think.
From the engine point of view, if you're looking at running a standard Sti7 engine with your turbo set up etc, then It's probably viable. The guys on NASIOC have done the most in this regard, where putting in a Sti short engine from japan is a common thing. Plenty of reports of running what must be over 400 crank HP on the standard engine (but then what is john banks doing?), one has even got 425wheel HP on such a setup (but dyno numbers are flaky at best in the US).
The newer engines have uprated pistons over the previous Sti engines, and uprated rods which are supposedly (from Subaru info) made from a better alloy with better processes and I think even nutless bolts on the big end cap.
The new Sti crank has additional oil drillings on the mains, BE remains the same.
Sti7 heads with the AVCS would be a very nice addition I beleive, if you can get even a basic control of the AVCS (possible even without the factory electronics) then you would be looking at bringing the start of the useable powerband down 500 rpm (see results of Jeff Sponaungle on NASIOC).
What does all this mean? Maybe Subaru hasn't learnt it's lesson with regard to mapping for UK fuel yet? I don't know, but the actual engines seem very good for a standard unit.
Paul
03 April 2003, 08:27 AM
#9
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As the boost is going up to over 20 PSI at 6.500 RPM under high loads (5th gear) with only small exhaust modification, it doesn´t wonder me engines are blowing! (injectors and fuel pump aren´t able to supply enough fuel for a decent mixture)
First thing we did before upgrading any STi, was to cure this problem of boost creep. Porting the wastegate to 27 mm is the solution that works perfectly. (we could reduce boost to 9 PSI under full load and high revs if we wanted to)
Mark.
First thing we did before upgrading any STi, was to cure this problem of boost creep. Porting the wastegate to 27 mm is the solution that works perfectly. (we could reduce boost to 9 PSI under full load and high revs if we wanted to)
Mark.
03 April 2003, 11:08 AM
#10
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Location: Leeds - It was 562.4bhp@28psi on Optimax, How much closer to 600 with race fuel and a bigger turbo?
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Paul,
Any idea on how the sti7 heads work, ie I presume its a solenoid to move something.. I assume the cam slides or similar??
Similar to VTEC or BMW VANOS?
David
Any idea on how the sti7 heads work, ie I presume its a solenoid to move something.. I assume the cam slides or similar??
Similar to VTEC or BMW VANOS?
David
04 April 2003, 05:54 PM
#12
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the variable timing is done at the pully which moves the whole camshaft via oil pressure which is pumped to the inside of the pully and then presses against vanes so oil directed to one side will advance the camshaft and then pumped to the other side retard the camshaft this is all controlled by a solenoid valve on the top of the head which is ecu controlled.
05 April 2003, 10:35 AM
#13
detailed explanation and diagrams of the AVCS to be found via NASIOC. But basically as described by scoobyboy. Control is via a PWM input to the system which is varied to give a different cam timing.
Tests by some guys in the US suggest the AVCS system is equivalent to 500rpm better spoolup, and better torque when off boost completely. Would be nice to get hold of some heads or AVCS pulleys and control system.
If only I was building an engine and needed a new pair of heads....
Paul
Tests by some guys in the US suggest the AVCS system is equivalent to 500rpm better spoolup, and better torque when off boost completely. Would be nice to get hold of some heads or AVCS pulleys and control system.
If only I was building an engine and needed a new pair of heads....
Paul
05 April 2003, 10:41 PM
#14
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IMHO, the following are issues with breathing mods and don't take much to trigger (so small safety reserves?) :
Fuel pump
No high RPM active knock control with a fairly optimistic base map for UK fuel
Boost creep
Fuel pump
No high RPM active knock control with a fairly optimistic base map for UK fuel
Boost creep
06 April 2003, 03:43 PM
#15
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Some cars I've seen are also pulling up to minus 8 degrees of timing between 5 and 6k on WOT. Not sure what impact this has on EGT's at this stage, but a bog standard car hacked around Dijon for 20 or so laps had a nice orangy-brown exhaust (no booster used) - after seeing it we did a lap with DeltaDash.... -6 degrees 
Not all cars suffer, and a new knock sensor doesn't help. However, problem is worse in tunnels suggesting it's noise related to some extent (on a car I saw with an aftermarket exhaust, a quieter backbox helped). Weird.
Richard
Not all cars suffer, and a new knock sensor doesn't help. However, problem is worse in tunnels suggesting it's noise related to some extent (on a car I saw with an aftermarket exhaust, a quieter backbox helped). Weird.
Richard
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