Squish B21FT for DD - Goals/Approach OK?

[jmclay]

I am interested in building a performance engine for my ’93 245 and would like to get some experienced reactions to my goals and basic plan for a B21FT Squish motor. The car has been my daily driver for the past 10 years and will remain so for the next 10.
Goals:
• Approx 225 shaft hp, just to throw a gross scaling number at it
• As close to 30 interstate mpg as possible
• Broad powerband
• Reliability. A car you wouldn’t hesitate to let your mother drive across the country for fear of engine problems

It ain’t a race car but I want respectible power and handling to match. No MegaSquirt or that sort of thing; beyond my area of interest. Standard components, more or less.

Approach/Component Selection:

I’ve been digesting turbo transplant, LH 2.2 & 2.4 info and squish engine threads intently of late. Based on that, here are my general ideas:

• B21FT bottom end for reduced displacement (maximize mpg) and the forged crank, M rods
• LH 2.2 (+ Chrysler Ignition?) for plentiful parts, reliability and adjustability. It sounds like the best choice anyway.
• Unclear of the head to use (compatible with LH 2.2/injector locations/type..?) but, basically stock, stock valve sizes, remove obvious hot spots, cc’d but leave the CC shape/footprint alone. Maintain squish area at all costs. Perhaps have someone who knows what they are doing just tidy things up a bit, but no more. I don’t get the feeling that a 405/531 head is necessary, or worth the $ for goal, but correct if wrong.
• B21F manifold (plenum)? Is that really worthwhile (hassle/benefit ratio) for this power level or are there better/easier choices that fill the bill?
• New pistons for higher SCR though I’m not sure where between the 8 and 9:1 ranges. I’ve not quite resolved the thread concerning 9:1 for street cars and 8:1 for race cars though I get the gist. Small diameter dish if needed for SCR adjustment.
• Pistons - forged/cast?
• Squish ~ 0.040”.
• Which cam?

I understand that there are many, many more fine points for later study (exhaust, injectors, turbo, ring placement, particular part number computers, engine management interconnections, etc., etc., etc.) but the go/no go question is: Can my goals be met in this basic package? If so, does it have relevant shortcomings that are better avoided, or are there better ways (not a new car)?

TIA
JClay

[olov]

AFAIK stealthfti has been running tight squish (stock part)b21 turbo's for years on stock management. you've searched and found his old posts right? at least you've read the aspirators post about "b21 buildup" right?

those are great places to start IMO. i will not attempt to answer your questions b/c i have no first hand experience, i've just read a lot of posts

and i stayed at a holiday inn express

[Canuckvolvo]

Sounds like you're doing your homework, that's great.

my 2c-

If you're looking for good economy, a high-ish static compression ratio is helpful, especially for "mom" driveability too. Alot is going to revolve around your pistons there. forged or cast doesn't matter, given your modest power goals, good cast pistons are fine.

Regardless of the CR, at 225hp you'll be looking at 15+psi of boost, and that's assuming you've upgraded the cam (pretty much anything but the T will do) intake (either manifold swap is better than stock), exhaust and have modified/upgraded the LH to handle it (AFAIK, it should manage 225hp without alot of mods). A larger turbo and better intercooler would be $ well spent.

In my opinion, a stock head with minimal mods will do for your power goals. Cleaning of ports, removing edges, polishing chambers, always good ideas.

Not sure about your transmission, but, stating the obvious, a manual puts more power down and gets more mpg than an automatic.

I'll also just add that less displacement doesn't ALWAYS mean better mpg. There are of course a million factors, but with a little more displacement, you get a little more torque, which means you need a little less throttle for a given load. To simplify, if it takes 40hp to cruise, a larger motor will be working less than a similar motor with less displacement. Always a balancing act of course, but i guess the point is don't let the 2.1litres dictate decisions when it comes to pistons. I'm sure that block would be ok to bore to 2.3 litres if you found a good deal on stock size 96mm pistons. I found a great deal on 2nd OS 2.1 litre pistons (that would give 2187cc).

good luck, keep us updated!

I've done three tight squish B230FTs in the last three years. All are at or above 10:1 SCR; all run 8PSI or higher on 87 octane. My next project is a tight squish B21FT at 10.6:1 SCR; and I will find out how much boost 87 octane will handle; and how much power 93 octane will make.

Re the 93 245 project:
...is it auto or manual tranny now? Will it remain that way?

the choice of going with a B21FT shortblock is good, for the reasons you gave; and for others as well. It would be compatible with whichever cyl head chosen, and whichever LH system chosen. As Athal stated, smaller displacement does not guarantee better economy, but there are some advantages to the 21FT that are hard to pass up.

headwise: use a 530. with the turbo sodium filled stellite faced exhaust valves; new late style valve springs. Prepped for evenness of flow and reliability. The power and economy will be derived from taking care of shortcomings elsewhere....cam, exhaust manifolding, turbo, exhaust system.

intake: the 230 intake will be quite adequate for your purposes; and is already ready for the LH injectors, etc.

LH system: 2.2 offers more user adjustability; your 245 already has 2.4. Either way, there will be computer changes to turbo ECUs. You will want to overlay in a 700/900 Turbo LH system.

ignition system: whether 2.2 or 2.4, go with the ign that comes with the 700/900 turbo LH sys that you will be using.

cam: Acam to start off with. Depending on how you do the exhaust and turbo, you might go as large as a KG2T.

motor internals: inspected and tested block, crank, rods: hot tanked and mag'd; rods fully resized and rebushed.

pistons to use: the deep dish 21FT pistons are usable; but I would recommend going with either a shallower dish piston or with flattops. Stock reinforced cast Mahles of either crown layout will be fine. I'll be using the Mahle flattops, 1st OS.

Squish: go for less than forty thou. Go for 0.030in to 0.032in. Mine will be about 0.026in to 0.028in, possibly tighter. With tight squish, you can utilize the the power and economy advantages of a higher SCR.

Retrofitting in oil squirters would be a better investment than forged pistons for your stated purposes.

Intercooling would be a bolt in; and an essential.

Exhaust: 3in turbo back.

Are your goals doable? Definitely. And should be very enjoyable.

Thomas Fritz
...the stealth FTi

I like your engine choice... I like your project... esp in a 245. Far be it from me to add to the excellent advice Athal and Thomas have already given, but I do have one bit to add...

If this engine is going into a 93 245, then you already have LH2.4... I would recommend leaving it in place for 2 reasons... 1. it's already there, and 2. it has the potential for chipping, both the fuel and ignition box. Check out the recent chipping discussion for more info on chipping in particular. Regardless, grab the turbo LH2.4 ECU and EZK116K ignition box from a turbo 740/940 and you're done.

I also like Stealth's suggestion of using a 530 head... I never thought of that. They'd be much easier to find than a scp 398.

Love the project ideas... I hope you go through with it.

Mike

Originally Posted by stealthfti

Re the 93 245 project:
0 I've done three tight squish B230FTs in the last three years. All are at or above 10:1 SCR; all run 8PSI or higher on 87 octane. My next project is a tight squish B21FT at 10.6:1 SCR; and I will find out how much boost 87 octane will handle; and how much power 93 octane will make.

1 ...is it auto or manual tranny now? Will it remain that way?

2 the choice of going with a B21FT shortblock is good, for the reasons you gave; and for others as well. It would be compatible with whichever cyl head chosen, and whichever LH system chosen. As Athal stated, smaller displacement does not guarantee better economy, but there are some advantages to the 21FT that are hard to pass up.

3 headwise: use a 530. with the turbo sodium filled stellite faced exhaust valves; new late style valve springs. Prepped for evenness of flow and reliability. The power and economy will be derived from taking care of shortcomings elsewhere....cam, exhaust manifolding, turbo, exhaust system.

4 intake: the 230 intake will be quite adequate for your purposes; and is already ready for the LH injectors, etc.

5 LH system: 2.2 offers more user adjustability; your 245 already has 2.4. Either way, there will be computer changes to turbo ECUs. You will want to overlay in a 700/900 Turbo LH system.

6 ignition system: whether 2.2 or 2.4, go with the ign that comes with the 700/900 turbo LH sys that you will be using.

7 cam: Acam to start off with. Depending on how you do the exhaust and turbo, you might go as large as a KG2T.

8 motor internals: inspected and tested block, crank, rods: hot tanked and mag'd; rods fully resized and rebushed.

9 pistons to use: the deep dish 21FT pistons are usable; but I would recommend going with either a shallower dish piston or with flattops. Stock reinforced cast Mahles of either crown layout will be fine. I'll be using the Mahle flattops, 1st OS.

10 Squish: go for less than forty thou. Go for 0.030in to 0.032in. Mine will be about 0.026in to 0.028in, possibly tighter. With tight squish, you can utilize the the power and economy advantages of a higher SCR.

11 Retrofitting in oil squirters would be a better investment than forged pistons for your stated purposes.

12 Intercooling would be a bolt in; and an essential.

13 Exhaust: 3in turbo back.

14 Are your goals doable? Definitely. And should be very enjoyable.

Thomas Fritz
...the stealth FTi

0 There is ample time before I'm committed to CR but for talking's sake are you thinking near 10 for this engine? This is virgin territory for me. All the cars you mentioned well mannered, long term reliable in my context of use and as they relate to CR for my car?

1 Auto now, M46 + OD then. I understand that there is a particular variant that would be preffered though I can't recall which/why right now. I also hear that M47s are hard and expensive to come by, hence the M46 route. Oh, which flywheel and clutch?

2 "the choice of going with a B21FT shortblock is good" Is it most likely to meet my goals though, particularly if smaller doesn't (in our context/reality here) guarantee higher mpg? What I mean is, if more than one type of shortblock could do the performance/tractibality and reliability ends of the job, I'd rather pick the one that would give the highest mpg. Is the B21 the more likely candidate in that context?

Is there a thrust bearing difference in the B21FT? Matters? What are the other advantages to it?

3 Yes to all. I completely subscribe to what I'll call your "first principles" (other posts) re these subjects. Don't sacrifice squish area, don't screw up a pretty decent CC or pretty good runners or good ports and valves and don't sacrifice squish area. At least by my logic/experience it makes too much sense to ignore. It would be easy to reduce performance. That I know; decades ago I used to occasionally do that with my motocross engines. I can see some conservative tidying up, house keeping; no more than that.

4 Good, that will save some grief.

5 I'll get or have access to a donor 2.2 740/940 turbo car for all things computer/harness/induction/IC etc. Any particular years perferable? Later for newer computers and aren't the '89 and earlier the ones that had dodgy wiring insulation?

6 10-4

7 Exhaust + turbo. I'm told that the Mitsu spins up quicker, lasts longer, has a more convenient manifold from the mechanic's point of view. Is this the ticket? Something else?

8 Yes to all + line bore, re-bore cylinders (no hone) (with head plate) block. I'm organizing some of your posts on the subject into a prescription and order of execution.

9 Select deep/flat based on gettng cc's/SCR closest to correct via piston, no? These will come with suitable ring land placement for good longevity of top ring?

10 OK. Are my knees shaking?

11 I'll search for how to retrofit squirters

12/13 Of course/of course. Are some ICs preferable; more durable, better heat transfer, whatever? I'll ask specific exhaust (downstream of turbo) questions later.

Many thanks Thomas.

740 ATL: Thanks for the input. The inability to alter ignition timing, except by chipping, is driving me away from 2.4. I don't want to get into any chipping really and I don't think I need to with 2.2. Now if my goals can be met with unchipped 2.4 then let me know. This really is a DD and I don't want to have a second thought as to reliability/repairability (other than you'd have in any event), say, 8 years from now when my wife and I decide to check out Mt Rushmore or some such.

As to project likelyhood; it's darn likely but I want to get a firm handle on the details before pulling the trigger. I really like the 240 format. I could have stolen a nice '90 745T last week but I couldn't/wasn't about to exchange the 245 for that. I like this car too much better but I'd like to solve the power issue, and the VX, though improved, is far short.

Must go for now. Thanks again, all.
John

[Canuckvolvo]

If you have access to a 940T donor, it will be LH2.4, same for any 740 1990 and up. I suspect you wouldn't regret not having spark adjustability, and there are other advantages to 2.4 over 2.2. With a well thought out tight squish motor, you'll actually be able to take advantage of the more aggressive spark curve of 2.4. Others may have different opinions.

Nothing wrong with the mitsu, but the stock one will be much too small for your goals. Yes, the later manifold is pretty much a required upgrade (as I'm sure you've read) and a garrett is easy to get to fit on it, especially if you can get a garrett with a stepped flange. Lots of info on turbos (and ICs) around, but bigger than stock will make things much safer/reliable.

[JW240]

why not go with a B230 (or B200, but that was probably not available). Lower friction design, higher CR turbo versions, lighter parts...?
I can advice to read stealthfti's Pbase, lots of excellent info and pics!

[The Aspirator]

^^ Yeah that's what I was thinking, if you've already got a '93 B230F with 9.8:1 compression in your car, why not just build that for toight squish? That'll also bump up the SCR a few tenths. Plus it already has all the goodies you want, 530 head, B230 intake mani, proper idle motor for 2.4, etc etc. Just get the turbo ECU's from turbo 700/900 cars and you should be good (although I'm not quite sure how the turbo ecus will deal with the higher compression... F+T question I guess). There's a guy on here called "thelostartof" who must be pushing 250+hp to the wheels with LH2.4, although I can't remember if his is chipped or not. But anyways, for your goals I think 2.4 might suit you just fine.

I understand your desire for ultimate reliability, and I think you'll have all the mechanical parts done and perfect without hassle. If anything is going to give you trouble I'd look at the electronics. Just be careful and methodical when buying and installing everything.

[jmclay]

CanuckVolvo wrote:
"If you have access to a 940T donor, it will be LH2.4, same for any 740 1990 and up. I suspect you wouldn't regret not having spark adjustability, and there are other advantages to 2.4 over 2.2. With a well thought out tight squish motor, you'll actually be able to take advantage of the more aggressive spark curve of 2.4. Others may have different opinions.

Nothing wrong with the mitsu, but the stock one will be much too small for your goals. Yes, the later manifold is pretty much a required upgrade (as I'm sure you've read) and a garrett is easy to get to fit on it, especially if you can get a garrett with a stepped flange. Lots of info on turbos (and ICs) around, but bigger than stock will make things much safer/reliable."

My reply/questions:
Maybe I’ve overstretched. This is the extent of my understanding of LH and associated ignition systems:
1) "2.2+it's ignigion system is more adjustible." I think the context is adjustible without programming changes, particularly wrt basic spark timing.
2) My EZK+2.4 won't allow ignition timing changes without programming changes.
3) A lot of folks seem to use 2.2 and I hear that it's reliable.
4) 2.4 (and ignition??) has "adaptive capabilities" though I don't know much about them nor the ranges of adjustment.

Back to first principals: I know I don't want to do any ECU or ignition system programming and I'd rather not get a custom chipped system if it can be avoided while meeting goals. Those are my car computer parameters. If 2.4 can fill the bill within those parameters then I should learn more about it. Do the adaptive abilities of 2.4 and it's ignition system (from a turbo car) extend to optimizing spark timing for a squish motor? Will it automajically find best spark timing for a high SCR squish motor? Seems unlikely to me since it's optimization algorithm would have been based on the different mixture burn rates and characteristics of a non squish motor. I could easily be wrong but that's where my thinking takes me. It's also as far as it takes me. Thoughts?

JW240 and The Aspirator lines of inquiry: “why not go with a B230 (or B200, but that was probably not available). Lower friction design, higher CR turbo versions, lighter parts...?
I can advice to read stealthfti's Pbase, lots of excellent info and pics!”

My reasons, which may be faulty but seem reasonable:
I’m assuming that for a same/same buildup I could realise better fuel economy in daily driving with a B21 based engine than B230. But, if folks are approaching 30 crusing mpg with B230FT based engines of this type then I’d be mighty interested to know as that could change things. On the other hand if that’s the case it seems not unreasonable to exceed 30 with the B21 based engine and that would be very nice. So I guess the question - am I wrong to suppose the B21 would get better mpg (say at least 3 or 4?) than the B230?

Low friction, lighter parts? What makes it lower friction? No challenge it’s just know I know nothing about this. Turbo will be new so it can be selected with suitable geometry. Pistons will be new.

As to Thomas’ posts – I’m reading them faster than I ought to. Letting other things slide.

And my B230F? It’s going to be true to what it is and will power the car until all is squared away for a brisk transplant of a new engine, tranny and associated bits. That's the idea anyway and using basically stock components will help support that effort. The components I'd use from it are easily obtainable here.

Thank you all for the feedback and ideas.
John

In a "same/same" build, the extra ten cubes will give the advantage overall to the larger displacement motor.

During certain conditions the smaller displacement 'can' be more fuel efficient...as in running on the flats at light load cruise. But where there is more load, the extra inherent torque of the ten extra cubes will tip the balance that way.

It will also be easier to maintain good driveability with the larger displacement.

SCR does not detemine smooth operation or not. Camshafts do that [oversimplified, I know]. Higher SCR can lower the BSFC, as well as improve the off idle and light throttle response. Higher SCR improves the torque down low.

Tight squish enables the use of higher SCR without the usual octane increase requirement penalty incurred when going higher SCR. The third TS motor is at thirty thou squish clearance. And that is with the 'shorter' B230 pistons. The limiting factor of how tight to go is the absolute redline: when the pistons start to kiss the cylinder head. With a manual trans, the use of an effective and functioning rev limiter is requisite as the squish clearance decided on gets tighter.

The three tight squish motors I have done are all running stock LH 2.4. no prob. Smoothness, good driveability, absolute reliability were all important considerations; as were fuel efficiency and reduced octane sensitivity. All goals were met or exceeded with no loss in power levels at all. High[er] performance is not just HP and lbs/ft numbers.

You can reach your goals with either a 131 cube or a 141 cube motor [or a 151 cuber]. Going manual trans will be an important factor in the MPG goal attainment.

The plan of basing a motor on the B21FT shortblock is viable and doable, but not the 'only' way to go, nor is it the only 'ultimate' way to go. That gets into serious bench race territory, but more importantly, it gets into serious expenditure territory....when you start talking 'ultimate' anything. I'll leave the 'ultimate' discussions for others to enjoy.

When you say 'for the next ten years', how many miles does that represent? The total miles expected in the motor life cycle can be a factor in deciding which iteration of the redblock to base the build on. As I think on that, I want to clarify that a bit: it IS an important factor.

When getting into which LH sys to go with, that can get really involved. Both 2.2 and 2.4 have their advantages and strong points. Learning more about both would be a good thing to do at this point. The final decision as to which to choose can wait; and should wait until the basic motor build plan is decided on.

HTH

TF

[jmclay]

"The three tight squish motors I have done are all running stock LH 2.4. no prob. Smoothness, good driveability, absolute reliability were all important considerations; as were fuel efficiency and reduced octane sensitivity. All goals were met or exceeded with no loss in power levels at all. High[er] performance is not just HP and lbs/ft numbers."

That's describes what I want with better than stock turbo power and no chipping/programming.

For the sake of context: My reaction to 2.4 was due to being informed, after I installed the VX cam, that static ignition timing was fixed. My very old school reaction was that that was bad but maybe thats flawed logic; it's based on my understanding of 30 year old approaches to power. 2.2/2.4 are on the back burner

10 years = 150k miles
I'll pull a 2000# trailer occasionally
Manual transmission
Fuel Injection and ignition: later + more reading/info
Basic block, internals, head: Thought I knew but now I think I'll pipe down, listen and ease to the back of the class.

Thanks Thomas
John

John, no need to feel like you need to pipe down. Unless you ask a question, it is kinda on the hard side to get an answer. so no prob. MAYBE...if you had asked dumb or REALLY dumb questions, or stupid questions, or LAZY questions. But you didn't and haven't. It's been a good discussion; and will continue to be so, whenever you want.

150K miles: that widens the horizons considerably.
the occasional 1 ton trailer gives more displacement a boost in votes.
manual trans: an M46 with P type OD would be excellent [later '80s 700s for source]; but even an M46 that has a J type OD would be fine.

Your reaction to 2.4 not being adjustable is valid. [my very first reaction to 2.4 was identical to yours: 'can't adjust timing or fuel mix? what a POS!!!!!'. I have since altered that evaluation.] That deficiency of 2.4 IS a PITA in some ways. As is the non adjustable AMM [016] used with 2.4. But, the adaptive memory of 2.4 is fairly robust. The full capability of 2.4 is still being explored.

For some of what you want to do, 2.2 offers some advantages towards those ends. But we can and will get into that as time progresses, and the need arises.

And...
...you're welcome.

TF

[mikep]

Originally Posted by stealthfti

Unless you ask a question, it is kinda on the hard side to get an answer.

Well put.

[jmclay]

Originally Posted by stealthfti

150K miles: that widens the horizons considerably.
the occasional 1 ton trailer gives more displacement a boost in votes.
manual trans: an M46 with P type OD would be excellent [later '80s 700s for source]; but even an M46 that has a J type OD would be fine.
TF

The 2000# trailer is a very, very occasional thing in rural areas. I'd rather bias the engine choices way towards better overall fuel economy; decent in stop/go driving and better on the highway. I keep wanting tractability. I drove a turbo diesel Passat for a week last year and the low end was really nice to have - not that I expect to match it.

I was looking at my Bently book and saw that the B230 pistons are shorter and have a higher wristpin location. I'm guessing that's to reduce friction and the tendency of the piston to cock in the cylinder for wear reduction/mpg. I seem to recall that the B230 cranks have counterweights on all cheeks, B21s on every other one. Would this make the B230 smoother and longer lived? Those musings aside, which engine would you suggest for this project at this point? The displacement difference is ~ 8% so I guess that wouldn't have a catastrophic impact on mpg. The L block has squirters, unsure of the crank but I'm guessing it can be smoother than the '21, shorter pistions (?), stronger rods, larger wrist pins as I recall --- is all this starting to suggest an L block turbo motor project core? That would be simpler.

John

[Lord_Athlon]

The b230 also has a tendency to develop piston slap...its kinda annoying. For that reason alone i would stay with the b21FT. PLus, the b21ft has thicker cyl walls then a b230.