Tuning post 1990 vs pre 1990 b230ft

[Bungcheezy]

I’m looking into buying a 1988 740 turbo wagon, with the hopes of tuning the redblock. I was watching some videos on people doing engine rebuilds and tuning their redblocks and came across a video where the mechanic mentions how the b230 prior to 1990 “isn’t a good block to start with” compared to the post 1990 version. I believe this was due to the thrust bearings being in the center of the block and it being a low friction engine. I don’t have much knowledge when it comes to engines and was wondering if someone could explain the cons of the pre 1990 b230ft and what it would mean tuning wise, and if the video series would still apply to my situation. Thank you in advance!

[YOUTUBE] https://youtu.be/VNxQsHJuU3g[/YOUTUBE]
Time stamp 3:09

[360beast]

Do you mean you have a 1988 740 or a 1998 940?

If it is a 1988 you will also have the skinny 9mm rods which have snapped on standard power before (Dai's brother did it) and a few people on turbo bricks have too.

Ideally you would want a B230 from 1993 onwards so it has the 13mm rods, upgraded thrust bearing location and oil squirters but the oil squirters aren't a necessity.

I think the designation is an L block that is the one to use for tuning but I can't remember for sure off the top of my head.

It also depends what you've got in mind, 200hp is easily achieved with a 740 turbo but 300hp is more involved and obviously as the power goes up so does the expense etc.

[Bungcheezy]

Oops, yeah, I don’t own it yet but it’s a 1988 740 turbo. Would upgrading the rods be of any help or is that engine sort of a lost cause for significant tuning? I was going to aim for around 350-400hp

[classicswede]

for upto around 300BHP the engine you have would be fine provided you changed the rods.

For your power goal the later stronger crank bottom end will be better but that will still want fitting with H beam rods. You want a late block with oil squirters really.

The engine you have should have a 531 head and that is a little better than the later 530 heads so would be worth combining the best of the two

[Bungcheezy]

Thank you for the help! I’ll for sure replace the rods, and that’s good to know about the block and head. My only question now would be regarding the engine being a low friction engine and what that means for tuning. The guy in the video pointed it out like it was a sizable issue and I’m not really sure how.

[classicswede]

The 85-88(89?) main bearing journal is only 55mm and uses a centre thrust washer. The centre thrust washer system is not great but can be improved by machining the centre cap so that both the block and cap have a thrust washer. You are still left with a 55mm weaker crank but still good for 3-400BHP at most before becoming a high risk of failure

89 on has 63mm main bearings and is back to the original end thrust setup. The crank is safe to around the 500BHP mark with failures starting to be seen in the 600bhp+ region. All the aftermarket upgraded cranks are for these blocks

The 85-88 bottom end once fitted with better rods be it the later 13mm rods or a set of H beams is prefectly fine for a typical build upto around the 300bhp mark. The original 9mm rods are a risk every time you drive. I have had 6 failures and some in NA engines so its not down to boost level. I know of a lot more that have failed

[Bungcheezy]

Thank you that’s really good to know, I was going to increase turbo pressure and daily it for now until I had the money to work on it but it sounds like that isn’t the smartest move. Would I theoretically then be able to swap the bottom end for the newer one but keep the headers and other engine components? And this might be a dumb question but is there anyway to possibly get the block machined it allow the larger thrust bearings or is that not an option? Thank you again for the help!

[classicswede]

It might be possible to get the block machined but between the cost of machining, replacing the crank and adding the oil sprays swaping the bottom end for a later one would cost less.

Everything that bolts onto the engine is the same or interchangeable

[classicswede]

The other consideration is the fuel system you have now. Uk market car would be on Motronic, other markets could be LH2.2 or LH2.4.

With your power goal you will be wanting to change the flywheel anyway combined with a stronger clutch if manual and also a gearbox that will handle the power. If Auto you need to change the flexplate or fit a trigger wheel to the front crank pulley. You power goal is beyond what LH2.4 is really capable of so you will need a mappable engine management system

[Bungcheezy]

I appreciate the help, I just got the car and I’m right now looking into buying a newer lower end and look into the modifications you mentioned. Still have a lot to learn, I’m completely brand new to this stuff but I’ve had a huge interest for a while especially with Volvo.