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ECU Swapping...

Help, Advice and DIY Tutorials on Volvo's P80 platform cars -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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RexSpeed
Posts: 24
Joined: 17 December 2009
Year and Model: '97 855 GLT
Location: Eau Claire, WI

ECU Swapping...

Post by RexSpeed »

Looking for some cheap and easy HP for my '97 GLT. "R" ECUs are a bit pricey but it seems that "Turbo" ECUs are relatively cheap and plentiful. So what's the general advice about swapping ECUs between the high-pressure cars and the low-pressure cars? I've read a bit about swapping between the R and the Turbo, but can't find anything on ECU options for the GLT.

I'm really not looking for a big project here, would just like to unplug one and plug in another and add another 20-30 ponies.
Rex in Wisconsin
------------------------------
'97 855 GLT (my 'nice' car)
'91 Mazda Miata (STS autocrosser)
'95 Subaru Legacy (wife's appliance)

JRL
Posts: 9350
Joined: 22 November 2005
Year and Model: Several
Location: 19333
Been thanked: 16 times

Post by JRL »

DON'T
You need a proper LPT chip/flash
Mod note. Jim passed away in early 2022, his contributions to this forum are immortal, and he is missed. RIP

2000 V70R Black, 144,000 miles Wife's R.
2007 V70 2.5T White/Oak 111,000 MILES. Polestar tune, IPD bars, rear spoiler, dark grey Thors, DWS 06, HU850, sub.

RexSpeed
Posts: 24
Joined: 17 December 2009
Year and Model: '97 855 GLT
Location: Eau Claire, WI

Post by RexSpeed »

JRL wrote:DON'T
You need a proper LPT chip/flash
Thank you. Exactly the kinda of definitive answer I've been searching for. What are the differences, why can't I just swap ECUs? (not being snotty, just curious)
Rex in Wisconsin
------------------------------
'97 855 GLT (my 'nice' car)
'91 Mazda Miata (STS autocrosser)
'95 Subaru Legacy (wife's appliance)

JRL
Posts: 9350
Joined: 22 November 2005
Year and Model: Several
Location: 19333
Been thanked: 16 times

Post by JRL »

Because of the smaller turbo and (MUCH) lower rev limit on an LPT, the entire power curve is different.
I'm not sure if it would even work properly..... (if at all)!
Mod note. Jim passed away in early 2022, his contributions to this forum are immortal, and he is missed. RIP

2000 V70R Black, 144,000 miles Wife's R.
2007 V70 2.5T White/Oak 111,000 MILES. Polestar tune, IPD bars, rear spoiler, dark grey Thors, DWS 06, HU850, sub.

RexSpeed
Posts: 24
Joined: 17 December 2009
Year and Model: '97 855 GLT
Location: Eau Claire, WI

Post by RexSpeed »

Correct me if I'm wrong, but aren't the rev limiter and power curve (by way of ignition timing and fuel mapping) both controlled by the ECU? If I swap ECUs I would then have the Turbo rev limiter and "power curve". I'm pretty sure the 13g turbo is at least capable of generating 11 pounds of boost. Are there differences in compression ratio? How about cam profiles and valve springs? Am I even further off the mark here and the internals themselves are completely different?
Rex in Wisconsin
------------------------------
'97 855 GLT (my 'nice' car)
'91 Mazda Miata (STS autocrosser)
'95 Subaru Legacy (wife's appliance)

JRL
Posts: 9350
Joined: 22 November 2005
Year and Model: Several
Location: 19333
Been thanked: 16 times

Post by JRL »

Cams and compression ratio is different.
Ask yourself this, if this worked why haven't LPT owners done this?
There are many HPT ECUs lying around in junk yards
Mod note. Jim passed away in early 2022, his contributions to this forum are immortal, and he is missed. RIP

2000 V70R Black, 144,000 miles Wife's R.
2007 V70 2.5T White/Oak 111,000 MILES. Polestar tune, IPD bars, rear spoiler, dark grey Thors, DWS 06, HU850, sub.

jblackburn
MVS Moderator
Posts: 14043
Joined: 8 June 2008
Year and Model: 1998 S70 T5
Location: Alexandria, VA
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Post by jblackburn »

The LPT engines are designed as a "high torque, low rev" design. They tend to act more like a big I6 or V8 engine in a Jeep - the redline isn't as high, but they have gobs of torque at the low end. Much of that is due to the boost patterns of the turbo - the T5's powerband is entirely different.

At the least, if you want more power, you can run a manual boost controller at 9-10 PSI or so or swap on a 16T. But as Jim said, just swapping in a T5/R ECU isn't gonna do you any good.
'98 S70 T5
2016 Chevy Cruze Premier


A learning experience is one of those things that says, "You know that thing you just did? Don't do that."

mercuic: Long live the tractor motor!

RexSpeed
Posts: 24
Joined: 17 December 2009
Year and Model: '97 855 GLT
Location: Eau Claire, WI

Post by RexSpeed »

Thanks for the knowledge. Not sure if I'm ambitious enough for a turbo swap, but I'll definitely heed your advice about ECUs.
Rex in Wisconsin
------------------------------
'97 855 GLT (my 'nice' car)
'91 Mazda Miata (STS autocrosser)
'95 Subaru Legacy (wife's appliance)

JRL
Posts: 9350
Joined: 22 November 2005
Year and Model: Several
Location: 19333
Been thanked: 16 times

Post by JRL »

Much cheaper to just buy a dedicated chipped ECU
These engine are a lot of fun chipped.
TONS of low and mid rnage torque and make a fun street car
I had a (chipped) 98 GLT, it was a monster off the line and mid range.
You could light up the tires for 200'!
It just pukes out at about 5200 RPM though
Mod note. Jim passed away in early 2022, his contributions to this forum are immortal, and he is missed. RIP

2000 V70R Black, 144,000 miles Wife's R.
2007 V70 2.5T White/Oak 111,000 MILES. Polestar tune, IPD bars, rear spoiler, dark grey Thors, DWS 06, HU850, sub.

RexSpeed
Posts: 24
Joined: 17 December 2009
Year and Model: '97 855 GLT
Location: Eau Claire, WI

Post by RexSpeed »

JRL wrote:Much cheaper to just buy a dedicated chipped ECU
Where and how much? IPD's is way more money than I can afford. Would you suggest that a proper chip/ECU is sufficient or should I plan to invest in some exhaust work too?

I'm not really looking for a stop light monster, just want a bit more oomph.
Rex in Wisconsin
------------------------------
'97 855 GLT (my 'nice' car)
'91 Mazda Miata (STS autocrosser)
'95 Subaru Legacy (wife's appliance)

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