96 1.8 BP05 Rebuild Advice

[RileyR]

Hi all,

My 1996 1.8L BP05 engine is smokey and sad, after 170,000km and some track abuse. I am fairly certain valve seals (or guides?) and rings are a bit sad. So bottom and top end rebuild?

The cheapest and probably easiest option is to buy a decent 2nd hand motor (possibly with 100k km on the engine). However, I am leaning towards a rebuild of my existing engine for a few reasons. Firstly, It may be difficult to find a suitable engine. Secondly, I want to retain my current ECU and not have to fiddle with tuning, or the cost of an aftermarket ECU. Thirdly, I want a reliable, rock solid engine that can handle some abuse.

I think keeping the stock ECU in place is a good way to ensure that I don't end up with a stupidly expensive rocket (which I know I want, but really shouldn't spend the money on).

I figure my budget is $4,000 - $5,000 for the rebuild.

My 3 goals for the build: 1. Rock solid reliable. 2. Within the 4-5K budget. 3. As much power from stock ECU that the budget will allow.

My question is what would you do with that budget?

What work or aftermarket parts would you consider?

[GR124]

If you buy another low KM used engine it would be the cheapest (around $2000) and easiest way to go. If it's the same engine model then it should be a plug n play, your original ECU should work and no tuning required.

[greenMachine]

I ran a big HP engine in my original NB8A GreenMachine. Serious cams, head work, extractors, decked block. Stock ECU, stock injectors, stock pistons/rods (balanced). Tuned by adjusting the fuel pressure. Not the most sophisticated setup, but brutally effective. The lack of sophistication was shown up in the idle (or lack thereof), and very hot/very cold start, but show it the wellie, and that was forgotten . Ultimately, it got a bit wearing around town, and an ECU was installed, a night and day difference.

Point of this is that you can do a hell of a lot and still use the stock ECU. Not suggesting you need to go to the extreme I did, but you have a lot of scope.

If you want cheap, I'd try for the replacement engine. See what turns up, if a good deal is around grab it, install, and go and have some (lots!) fun. Rebuild your (now) spare engine at leisure.

There are some things you will need to do if recoing your existing engine - guides, rings, bearings, hone the bores, maybe polish/grind the crank (how is your crank nose?), valves/seats perhaps. Hopefully no rebore, because that will require pistons. Simplest performance option is extractors, and match the ports on both exhaust and inlet sides. Next a mild cam grind. All of that should be OK on a stock ECU running stock fuel pressure, depending on what you call a 'mild' cam. Going further (increasing CR, wilder cams, etc) will very quickly take you to a AFPR and a dyno tune or an ecu instal.

Add a 6-speed with a 4.1 diff, some decent pads and tyres, and you have a low stress but high fun car that will be a ball in the mountains or on the track.

[project.r.racing]

IF you shop around right and aren't in a rush, for about $4K, you could do a full rebuild and add some ecu friendly cams eg 252d 9mm lift cams. You'll have change left over for other performance mods.

[16bit]

you have a very middle ground budget for what you want to do from my eye.

you have much more money than you need for a replacement wrecker motor but not enough for a performance rebuild with all the bits that it requires (ecu, fuel, supporting mods if you dont have any like exhaust and intake etc etc).

my personal opinion would be to find someone who has done a vvt swap into an na8 chassi and do that.

[RileyR]

Thanks for the great comments every one! very helpful and informative!

apologies for the late reply i have been away over easter

If you buy another low KM used engine it would be the cheapest (around $2000) and easiest way to go. If it's the same engine model then it should be a plug n play, your original ECU should work and no tuning required.

I think i need to find a '96 or '97 16 pin ecu version of the bp05 to be plug and play?

I ran a big HP engine in my original NB8A GreenMachine. Serious cams, head work, extractors, decked block. Stock ECU, stock injectors, stock pistons/rods (balanced). Tuned by adjusting the fuel pressure. Not the most sophisticated setup, but brutally effective. The lack of sophistication was shown up in the idle (or lack thereof), and very hot/very cold start, but show it the wellie, and that was forgotten . Ultimately, it got a bit wearing around town, and an ECU was installed, a night and day difference.

Point of this is that you can do a hell of a lot and still use the stock ECU. Not suggesting you need to go to the extreme I did, but you have a lot of scope.

If you want cheap, I'd try for the replacement engine. See what turns up, if a good deal is around grab it, install, and go and have some (lots!) fun. Rebuild your (now) spare engine at leisure.

There are some things you will need to do if recoing your existing engine - guides, rings, bearings, hone the bores, maybe polish/grind the crank (how is your crank nose?), valves/seats perhaps. Hopefully no rebore, because that will require pistons. Simplest performance option is extractors, and match the ports on both exhaust and inlet sides. Next a mild cam grind. All of that should be OK on a stock ECU running stock fuel pressure, depending on what you call a 'mild' cam. Going further (increasing CR, wilder cams, etc) will very quickly take you to a AFPR and a dyno tune or an ecu instal.

Add a 6-speed with a 4.1 diff, some decent pads and tyres, and you have a low stress but high fun car that will be a ball in the mountains or on the track.

Thanks for the in-depth post! its great to know there is some scope for development with the original ECU! I'm thinking of coolant re-route, possibly some work to bottom end - possibly a balance? Definitely considering new cams! I dont want to go crazy, I just want a rock solid motor and possibly a bit more power. I will also be shedding some weight from it i think. possibly get rid of non essentials like power steering, aircon, he now torn soft top etc. shedding weight should make it a bit faster! Its already got extractors, exhaust, intake sorted. good pads and rotors, braided lines, mca coilovers, eccentric bushes, bigger front sway bar.

IF you shop around right and aren't in a rush, for about $4K, you could do a full rebuild and add some ecu friendly cams eg 252d 9mm lift cams. You'll have change left over for other performance mods.

sounds like cams are the way to go! good to know my budget isnt miles off!

you have a very middle ground budget for what you want to do from my eye.

you have much more money than you need for a replacement wrecker motor but not enough for a performance rebuild with all the bits that it requires (ecu, fuel, supporting mods if you dont have any like exhaust and intake etc etc).

my personal opinion would be to find someone who has done a vvt swap into an na8 chassi and do that.

yeah a very common opinion. it would be the cheapest way to a bit of extra horse power. It does mean i instantly go up a class in some of the sprints i am looking at getting into though.

I would love to know that i have a fresh as a daisy motor ready for fun.

[manga_blue]

I did a rebuild on my NA8 engine 12 years ago after a major long nose failure. At that time there weren't many replacement engines available but I was lucky enough to get a NB8B engine that had had an unfortunate meeting with a pole. The block and head were a write-off but the block internals were all salvageable.

So along with the salvage crank, rods and pistons the block got a light hone, end to end balance, race bolts, studs and bearings, light decking and a few other pieces of TLC. The head got a lot of work as well, some DIY and some rather expensive machining. All up cost was just north of $3,000.

I ran it for about 3,000 comp laps after that in limited mod classes and using a 7600 rev limit on virtually every shift. That engine is still in the car, albeit with a ported BP4W head now. It's still smooth and reassuringly bullet-proof.

Do I regret doing a rebuild? Never.

[RileyR]

I did a rebuild on my NA8 engine 12 years ago after a major long nose failure. At that time there weren't many replacement engines available but I was lucky enough to get a NB8B engine that had had an unfortunate meeting with a pole. The block and head were a write-off but the block internals were all salvageable.

So along with the salvage crank, rods and pistons the block got a light hone, end to end balance, race bolts, studs and bearings, light decking and a few other pieces of TLC. The head got a lot of work as well, some DIY and some rather expensive machining. All up cost was just north of $3,000.

I ran it for about 3,000 comp laps after that in limited mod classes and using a 7600 rev limit on virtually every shift. That engine is still in the car, albeit with a ported BP4W head now. It's still smooth and reassuringly bullet-proof.

Do I regret doing a rebuild? Never.

Just the post I needed to reasure me that a rebuild is the way to a bulletproof engine!

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[hks_kansei]

Just the post I needed to reasure me that a rebuild is the way to a bulletproof engine!

A good rebuild is.
A mediocre rebuild isnt.

The machining is the hard part, where precision is everything. But the assembly still needs some skill and care (stuff like a well calibrated torque wrench, and a knowledge of how to correctly prime/lube things during assembly, as well as knowing how to put stuff together properly)

If you're having the shop assemble the engine, then just make sure to check around for happy customers.
and follow the shop's recommendations re: running in etc.


Looking at your first post, have you had a compression test to see how the rings are?

If they're still sealing fine (they should with only 170,000km on it) then you probably only need the head rebuilt (well, probably just new valve guides, but regardless)

A lot easier, and a lot cheaper.

Last head my gf had rebuilt cost $800, but that was for a Holden Red motor (iron, pushrod so no cam stuff, plus converted to hardened valves and seats for unleaded fuel)

[RileyR]

Just the post I needed to reasure me that a rebuild is the way to a bulletproof engine!

A good rebuild is.
A mediocre rebuild isnt.

The machining is the hard part, where precision is everything. But the assembly still needs some skill and care (stuff like a well calibrated torque wrench, and a knowledge of how to correctly prime/lube things during assembly, as well as knowing how to put stuff together properly)

If you're having the shop assemble the engine, then just make sure to check around for happy customers.
and follow the shop's recommendations re: running in etc.


Looking at your first post, have you had a compression test to see how the rings are?

If they're still sealing fine (they should with only 170,000km on it) then you probably only need the head rebuilt (well, probably just new valve guides, but regardless)

A lot easier, and a lot cheaper.

Last head my gf had rebuilt cost $800, but that was for a Holden Red motor (iron, pushrod so no cam stuff, plus converted to hardened valves and seats for unleaded fuel)

Thanks hks. Maybe a bottom end build isnt needed. If it is only the valve seals or guides that are worn then maybe a some cams while the head is off?

I am going to get into contact with BnB engines down here in vic. A couple of members have recommended them. I was just going to hand it to them to do all the work.

No compression test yet. Would it be best to pre-empt a bottom end build and do it either way the compression test goes?

Maybe I should hand it to BnB Engines and just see what they recommend after having a look at it?

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[hks_kansei]

really depends on your budget.

If you're going through the effort of removing the entire engine, then you may as well have the top and bottom rebuilt together, if the budget allows.


BNB are a good option, they do good work and do a lot of engines for MGB racecars (as well as a lot of more standard stuff)

They're who my GF used to do the machine work on the Kingswood engine she rebuilt.

[RileyR]

Thanks hks. Another thumbs up for BNB!
Maybe i should speak to them about my budget and see what they recommend. It would be great to know that the engine is ready for another 170k km of abuse.

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[greenMachine]

I am guessing that you are not in Toowoomba Vic (is there such a place?), but have moved south? If so, you might want to update your profile

[RileyR]

I am guessing that you are not in Toowoomba Vic (is there such a place?), but have moved south? If so, you might want to update your profile

Haha nah no longer in sunny QLD. Updating now

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[bruce]

170K is not a lot of kilometres.
How many kays do you drive per year? How much longer do you think you will own the car (realistically)?
Hardly worth getting the whole motor rebuilt if it only needs the head done. You're just throwing money away (or giving it to the next owner).